2 /* pngread.c - read a PNG file
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4 * Copyright (c) 2018-2019 Cosmin Truta
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5 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
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6 * Copyright (c) 1996-1997 Andreas Dilger
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7 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
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9 * This code is released under the libpng license.
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10 * For conditions of distribution and use, see the disclaimer
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11 * and license in png.h
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13 * This file contains routines that an application calls directly to
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14 * read a PNG file or stream.
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17 #include "pngpriv.h"
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18 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
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22 #ifdef PNG_READ_SUPPORTED
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24 /* Create a PNG structure for reading, and allocate any memory needed. */
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25 PNG_FUNCTION(png_structp,PNGAPI
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26 png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
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27 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
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29 #ifndef PNG_USER_MEM_SUPPORTED
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30 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
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31 error_fn, warn_fn, NULL, NULL, NULL);
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33 return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
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34 warn_fn, NULL, NULL, NULL);
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37 /* Alternate create PNG structure for reading, and allocate any memory
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40 PNG_FUNCTION(png_structp,PNGAPI
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41 png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
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42 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
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43 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
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45 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
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46 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
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47 #endif /* USER_MEM */
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49 if (png_ptr != NULL)
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51 png_ptr->mode = PNG_IS_READ_STRUCT;
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53 /* Added in libpng-1.6.0; this can be used to detect a read structure if
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54 * required (it will be zero in a write structure.)
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56 # ifdef PNG_SEQUENTIAL_READ_SUPPORTED
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57 png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
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60 # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
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61 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
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63 /* In stable builds only warn if an application error can be completely
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66 # if PNG_RELEASE_BUILD
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67 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
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71 /* TODO: delay this, it can be done in png_init_io (if the app doesn't
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72 * do it itself) avoiding setting the default function if it is not
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75 png_set_read_fn(png_ptr, NULL, NULL);
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82 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
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83 /* Read the information before the actual image data. This has been
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84 * changed in v0.90 to allow reading a file that already has the magic
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85 * bytes read from the stream. You can tell libpng how many bytes have
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86 * been read from the beginning of the stream (up to the maximum of 8)
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87 * via png_set_sig_bytes(), and we will only check the remaining bytes
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88 * here. The application can then have access to the signature bytes we
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89 * read if it is determined that this isn't a valid PNG file.
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92 png_read_info(png_structrp png_ptr, png_inforp info_ptr)
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94 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
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98 png_debug(1, "in png_read_info");
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100 if (png_ptr == NULL || info_ptr == NULL)
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103 /* Read and check the PNG file signature. */
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104 png_read_sig(png_ptr, info_ptr);
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108 png_uint_32 length = png_read_chunk_header(png_ptr);
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109 png_uint_32 chunk_name = png_ptr->chunk_name;
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111 /* IDAT logic needs to happen here to simplify getting the two flags
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114 if (chunk_name == png_IDAT)
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116 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
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117 png_chunk_error(png_ptr, "Missing IHDR before IDAT");
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119 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
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120 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
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121 png_chunk_error(png_ptr, "Missing PLTE before IDAT");
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123 else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
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124 png_chunk_benign_error(png_ptr, "Too many IDATs found");
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126 png_ptr->mode |= PNG_HAVE_IDAT;
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129 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
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131 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
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132 png_ptr->mode |= PNG_AFTER_IDAT;
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135 /* This should be a binary subdivision search or a hash for
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136 * matching the chunk name rather than a linear search.
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138 if (chunk_name == png_IHDR)
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139 png_handle_IHDR(png_ptr, info_ptr, length);
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141 else if (chunk_name == png_IEND)
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142 png_handle_IEND(png_ptr, info_ptr, length);
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144 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
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145 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
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147 png_handle_unknown(png_ptr, info_ptr, length, keep);
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149 if (chunk_name == png_PLTE)
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150 png_ptr->mode |= PNG_HAVE_PLTE;
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152 else if (chunk_name == png_IDAT)
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154 png_ptr->idat_size = 0; /* It has been consumed */
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159 else if (chunk_name == png_PLTE)
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160 png_handle_PLTE(png_ptr, info_ptr, length);
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162 else if (chunk_name == png_IDAT)
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164 png_ptr->idat_size = length;
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168 #ifdef PNG_READ_bKGD_SUPPORTED
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169 else if (chunk_name == png_bKGD)
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170 png_handle_bKGD(png_ptr, info_ptr, length);
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173 #ifdef PNG_READ_cHRM_SUPPORTED
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174 else if (chunk_name == png_cHRM)
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175 png_handle_cHRM(png_ptr, info_ptr, length);
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178 #ifdef PNG_READ_eXIf_SUPPORTED
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179 else if (chunk_name == png_eXIf)
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180 png_handle_eXIf(png_ptr, info_ptr, length);
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183 #ifdef PNG_READ_gAMA_SUPPORTED
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184 else if (chunk_name == png_gAMA)
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185 png_handle_gAMA(png_ptr, info_ptr, length);
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188 #ifdef PNG_READ_hIST_SUPPORTED
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189 else if (chunk_name == png_hIST)
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190 png_handle_hIST(png_ptr, info_ptr, length);
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193 #ifdef PNG_READ_oFFs_SUPPORTED
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194 else if (chunk_name == png_oFFs)
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195 png_handle_oFFs(png_ptr, info_ptr, length);
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198 #ifdef PNG_READ_pCAL_SUPPORTED
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199 else if (chunk_name == png_pCAL)
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200 png_handle_pCAL(png_ptr, info_ptr, length);
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203 #ifdef PNG_READ_sCAL_SUPPORTED
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204 else if (chunk_name == png_sCAL)
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205 png_handle_sCAL(png_ptr, info_ptr, length);
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208 #ifdef PNG_READ_pHYs_SUPPORTED
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209 else if (chunk_name == png_pHYs)
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210 png_handle_pHYs(png_ptr, info_ptr, length);
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213 #ifdef PNG_READ_sBIT_SUPPORTED
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214 else if (chunk_name == png_sBIT)
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215 png_handle_sBIT(png_ptr, info_ptr, length);
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218 #ifdef PNG_READ_sRGB_SUPPORTED
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219 else if (chunk_name == png_sRGB)
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220 png_handle_sRGB(png_ptr, info_ptr, length);
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223 #ifdef PNG_READ_iCCP_SUPPORTED
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224 else if (chunk_name == png_iCCP)
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225 png_handle_iCCP(png_ptr, info_ptr, length);
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228 #ifdef PNG_READ_sPLT_SUPPORTED
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229 else if (chunk_name == png_sPLT)
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230 png_handle_sPLT(png_ptr, info_ptr, length);
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233 #ifdef PNG_READ_tEXt_SUPPORTED
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234 else if (chunk_name == png_tEXt)
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235 png_handle_tEXt(png_ptr, info_ptr, length);
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238 #ifdef PNG_READ_tIME_SUPPORTED
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239 else if (chunk_name == png_tIME)
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240 png_handle_tIME(png_ptr, info_ptr, length);
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243 #ifdef PNG_READ_tRNS_SUPPORTED
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244 else if (chunk_name == png_tRNS)
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245 png_handle_tRNS(png_ptr, info_ptr, length);
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248 #ifdef PNG_READ_zTXt_SUPPORTED
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249 else if (chunk_name == png_zTXt)
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250 png_handle_zTXt(png_ptr, info_ptr, length);
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253 #ifdef PNG_READ_iTXt_SUPPORTED
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254 else if (chunk_name == png_iTXt)
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255 png_handle_iTXt(png_ptr, info_ptr, length);
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259 png_handle_unknown(png_ptr, info_ptr, length,
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260 PNG_HANDLE_CHUNK_AS_DEFAULT);
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263 #endif /* SEQUENTIAL_READ */
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265 /* Optional call to update the users info_ptr structure */
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267 png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
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269 png_debug(1, "in png_read_update_info");
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271 if (png_ptr != NULL)
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273 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
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275 png_read_start_row(png_ptr);
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277 # ifdef PNG_READ_TRANSFORMS_SUPPORTED
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278 png_read_transform_info(png_ptr, info_ptr);
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280 PNG_UNUSED(info_ptr)
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284 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
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286 png_app_error(png_ptr,
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287 "png_read_update_info/png_start_read_image: duplicate call");
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291 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
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292 /* Initialize palette, background, etc, after transformations
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293 * are set, but before any reading takes place. This allows
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294 * the user to obtain a gamma-corrected palette, for example.
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295 * If the user doesn't call this, we will do it ourselves.
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298 png_start_read_image(png_structrp png_ptr)
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300 png_debug(1, "in png_start_read_image");
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302 if (png_ptr != NULL)
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304 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
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305 png_read_start_row(png_ptr);
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307 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
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309 png_app_error(png_ptr,
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310 "png_start_read_image/png_read_update_info: duplicate call");
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313 #endif /* SEQUENTIAL_READ */
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315 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
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316 #ifdef PNG_MNG_FEATURES_SUPPORTED
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317 /* Undoes intrapixel differencing,
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318 * NOTE: this is apparently only supported in the 'sequential' reader.
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321 png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
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323 png_debug(1, "in png_do_read_intrapixel");
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326 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
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328 int bytes_per_pixel;
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329 png_uint_32 row_width = row_info->width;
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331 if (row_info->bit_depth == 8)
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336 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
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337 bytes_per_pixel = 3;
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339 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
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340 bytes_per_pixel = 4;
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345 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
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347 *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
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348 *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
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351 else if (row_info->bit_depth == 16)
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356 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
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357 bytes_per_pixel = 6;
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359 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
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360 bytes_per_pixel = 8;
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365 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
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367 png_uint_32 s0 = (png_uint_32)(*(rp ) << 8) | *(rp + 1);
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368 png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
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369 png_uint_32 s2 = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
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370 png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
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371 png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
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372 *(rp ) = (png_byte)((red >> 8) & 0xff);
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373 *(rp + 1) = (png_byte)(red & 0xff);
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374 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
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375 *(rp + 5) = (png_byte)(blue & 0xff);
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380 #endif /* MNG_FEATURES */
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383 png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
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385 png_row_info row_info;
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387 if (png_ptr == NULL)
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390 png_debug2(1, "in png_read_row (row %lu, pass %d)",
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391 (unsigned long)png_ptr->row_number, png_ptr->pass);
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393 /* png_read_start_row sets the information (in particular iwidth) for this
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396 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
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397 png_read_start_row(png_ptr);
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399 /* 1.5.6: row_info moved out of png_struct to a local here. */
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400 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
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401 row_info.color_type = png_ptr->color_type;
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402 row_info.bit_depth = png_ptr->bit_depth;
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403 row_info.channels = png_ptr->channels;
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404 row_info.pixel_depth = png_ptr->pixel_depth;
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405 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
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407 #ifdef PNG_WARNINGS_SUPPORTED
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408 if (png_ptr->row_number == 0 && png_ptr->pass == 0)
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410 /* Check for transforms that have been set but were defined out */
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411 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
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412 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
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413 png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
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416 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
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417 if ((png_ptr->transformations & PNG_FILLER) != 0)
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418 png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
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421 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
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422 !defined(PNG_READ_PACKSWAP_SUPPORTED)
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423 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
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424 png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
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427 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
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428 if ((png_ptr->transformations & PNG_PACK) != 0)
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429 png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
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432 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
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433 if ((png_ptr->transformations & PNG_SHIFT) != 0)
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434 png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
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437 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
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438 if ((png_ptr->transformations & PNG_BGR) != 0)
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439 png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
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442 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
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443 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
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444 png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
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447 #endif /* WARNINGS */
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449 #ifdef PNG_READ_INTERLACING_SUPPORTED
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450 /* If interlaced and we do not need a new row, combine row and return.
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451 * Notice that the pixels we have from previous rows have been transformed
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452 * already; we can only combine like with like (transformed or
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453 * untransformed) and, because of the libpng API for interlaced images, this
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454 * means we must transform before de-interlacing.
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456 if (png_ptr->interlaced != 0 &&
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457 (png_ptr->transformations & PNG_INTERLACE) != 0)
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459 switch (png_ptr->pass)
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462 if (png_ptr->row_number & 0x07)
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464 if (dsp_row != NULL)
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465 png_combine_row(png_ptr, dsp_row, 1/*display*/);
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466 png_read_finish_row(png_ptr);
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472 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
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474 if (dsp_row != NULL)
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475 png_combine_row(png_ptr, dsp_row, 1/*display*/);
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477 png_read_finish_row(png_ptr);
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483 if ((png_ptr->row_number & 0x07) != 4)
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485 if (dsp_row != NULL && (png_ptr->row_number & 4))
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486 png_combine_row(png_ptr, dsp_row, 1/*display*/);
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488 png_read_finish_row(png_ptr);
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494 if ((png_ptr->row_number & 3) || png_ptr->width < 3)
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496 if (dsp_row != NULL)
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497 png_combine_row(png_ptr, dsp_row, 1/*display*/);
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499 png_read_finish_row(png_ptr);
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505 if ((png_ptr->row_number & 3) != 2)
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507 if (dsp_row != NULL && (png_ptr->row_number & 2))
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508 png_combine_row(png_ptr, dsp_row, 1/*display*/);
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510 png_read_finish_row(png_ptr);
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516 if ((png_ptr->row_number & 1) || png_ptr->width < 2)
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518 if (dsp_row != NULL)
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519 png_combine_row(png_ptr, dsp_row, 1/*display*/);
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521 png_read_finish_row(png_ptr);
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528 if ((png_ptr->row_number & 1) == 0)
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530 png_read_finish_row(png_ptr);
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538 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
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539 png_error(png_ptr, "Invalid attempt to read row data");
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541 /* Fill the row with IDAT data: */
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542 png_ptr->row_buf[0]=255; /* to force error if no data was found */
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543 png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
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545 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
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547 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
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548 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
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549 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
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551 png_error(png_ptr, "bad adaptive filter value");
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554 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
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555 * 1.5.6, while the buffer really is this big in current versions of libpng
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556 * it may not be in the future, so this was changed just to copy the
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557 * interlaced count:
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559 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
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561 #ifdef PNG_MNG_FEATURES_SUPPORTED
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562 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
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563 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
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565 /* Intrapixel differencing */
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566 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
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570 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
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571 if (png_ptr->transformations)
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572 png_do_read_transformations(png_ptr, &row_info);
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575 /* The transformed pixel depth should match the depth now in row_info. */
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576 if (png_ptr->transformed_pixel_depth == 0)
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578 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
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579 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
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580 png_error(png_ptr, "sequential row overflow");
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583 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
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584 png_error(png_ptr, "internal sequential row size calculation error");
\r
586 #ifdef PNG_READ_INTERLACING_SUPPORTED
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587 /* Expand interlaced rows to full size */
\r
588 if (png_ptr->interlaced != 0 &&
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589 (png_ptr->transformations & PNG_INTERLACE) != 0)
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591 if (png_ptr->pass < 6)
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592 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
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593 png_ptr->transformations);
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595 if (dsp_row != NULL)
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596 png_combine_row(png_ptr, dsp_row, 1/*display*/);
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599 png_combine_row(png_ptr, row, 0/*row*/);
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606 png_combine_row(png_ptr, row, -1/*ignored*/);
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608 if (dsp_row != NULL)
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609 png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
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611 png_read_finish_row(png_ptr);
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613 if (png_ptr->read_row_fn != NULL)
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614 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
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617 #endif /* SEQUENTIAL_READ */
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619 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
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620 /* Read one or more rows of image data. If the image is interlaced,
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621 * and png_set_interlace_handling() has been called, the rows need to
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622 * contain the contents of the rows from the previous pass. If the
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623 * image has alpha or transparency, and png_handle_alpha()[*] has been
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624 * called, the rows contents must be initialized to the contents of the
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627 * "row" holds the actual image, and pixels are placed in it
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628 * as they arrive. If the image is displayed after each pass, it will
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629 * appear to "sparkle" in. "display_row" can be used to display a
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630 * "chunky" progressive image, with finer detail added as it becomes
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631 * available. If you do not want this "chunky" display, you may pass
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632 * NULL for display_row. If you do not want the sparkle display, and
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633 * you have not called png_handle_alpha(), you may pass NULL for rows.
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634 * If you have called png_handle_alpha(), and the image has either an
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635 * alpha channel or a transparency chunk, you must provide a buffer for
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636 * rows. In this case, you do not have to provide a display_row buffer
\r
637 * also, but you may. If the image is not interlaced, or if you have
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638 * not called png_set_interlace_handling(), the display_row buffer will
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639 * be ignored, so pass NULL to it.
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641 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
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645 png_read_rows(png_structrp png_ptr, png_bytepp row,
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646 png_bytepp display_row, png_uint_32 num_rows)
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652 png_debug(1, "in png_read_rows");
\r
654 if (png_ptr == NULL)
\r
659 if (rp != NULL && dp != NULL)
\r
660 for (i = 0; i < num_rows; i++)
\r
662 png_bytep rptr = *rp++;
\r
663 png_bytep dptr = *dp++;
\r
665 png_read_row(png_ptr, rptr, dptr);
\r
668 else if (rp != NULL)
\r
669 for (i = 0; i < num_rows; i++)
\r
671 png_bytep rptr = *rp;
\r
672 png_read_row(png_ptr, rptr, NULL);
\r
676 else if (dp != NULL)
\r
677 for (i = 0; i < num_rows; i++)
\r
679 png_bytep dptr = *dp;
\r
680 png_read_row(png_ptr, NULL, dptr);
\r
684 #endif /* SEQUENTIAL_READ */
\r
686 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
\r
687 /* Read the entire image. If the image has an alpha channel or a tRNS
\r
688 * chunk, and you have called png_handle_alpha()[*], you will need to
\r
689 * initialize the image to the current image that PNG will be overlaying.
\r
690 * We set the num_rows again here, in case it was incorrectly set in
\r
691 * png_read_start_row() by a call to png_read_update_info() or
\r
692 * png_start_read_image() if png_set_interlace_handling() wasn't called
\r
693 * prior to either of these functions like it should have been. You can
\r
694 * only call this function once. If you desire to have an image for
\r
695 * each pass of a interlaced image, use png_read_rows() instead.
\r
697 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
\r
700 png_read_image(png_structrp png_ptr, png_bytepp image)
\r
702 png_uint_32 i, image_height;
\r
706 png_debug(1, "in png_read_image");
\r
708 if (png_ptr == NULL)
\r
711 #ifdef PNG_READ_INTERLACING_SUPPORTED
\r
712 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
\r
714 pass = png_set_interlace_handling(png_ptr);
\r
715 /* And make sure transforms are initialized. */
\r
716 png_start_read_image(png_ptr);
\r
720 if (png_ptr->interlaced != 0 &&
\r
721 (png_ptr->transformations & PNG_INTERLACE) == 0)
\r
723 /* Caller called png_start_read_image or png_read_update_info without
\r
724 * first turning on the PNG_INTERLACE transform. We can fix this here,
\r
725 * but the caller should do it!
\r
727 png_warning(png_ptr, "Interlace handling should be turned on when "
\r
728 "using png_read_image");
\r
729 /* Make sure this is set correctly */
\r
730 png_ptr->num_rows = png_ptr->height;
\r
733 /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
\r
734 * the above error case.
\r
736 pass = png_set_interlace_handling(png_ptr);
\r
739 if (png_ptr->interlaced)
\r
741 "Cannot read interlaced image -- interlace handler disabled");
\r
746 image_height=png_ptr->height;
\r
748 for (j = 0; j < pass; j++)
\r
751 for (i = 0; i < image_height; i++)
\r
753 png_read_row(png_ptr, *rp, NULL);
\r
758 #endif /* SEQUENTIAL_READ */
\r
760 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
\r
761 /* Read the end of the PNG file. Will not read past the end of the
\r
762 * file, will verify the end is accurate, and will read any comments
\r
763 * or time information at the end of the file, if info is not NULL.
\r
766 png_read_end(png_structrp png_ptr, png_inforp info_ptr)
\r
768 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
\r
772 png_debug(1, "in png_read_end");
\r
774 if (png_ptr == NULL)
\r
777 /* If png_read_end is called in the middle of reading the rows there may
\r
778 * still be pending IDAT data and an owned zstream. Deal with this here.
\r
780 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
\r
781 if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
\r
783 png_read_finish_IDAT(png_ptr);
\r
785 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
\r
786 /* Report invalid palette index; added at libng-1.5.10 */
\r
787 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
\r
788 png_ptr->num_palette_max > png_ptr->num_palette)
\r
789 png_benign_error(png_ptr, "Read palette index exceeding num_palette");
\r
794 png_uint_32 length = png_read_chunk_header(png_ptr);
\r
795 png_uint_32 chunk_name = png_ptr->chunk_name;
\r
797 if (chunk_name != png_IDAT)
\r
798 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
\r
800 if (chunk_name == png_IEND)
\r
801 png_handle_IEND(png_ptr, info_ptr, length);
\r
803 else if (chunk_name == png_IHDR)
\r
804 png_handle_IHDR(png_ptr, info_ptr, length);
\r
806 else if (info_ptr == NULL)
\r
807 png_crc_finish(png_ptr, length);
\r
809 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
\r
810 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
\r
812 if (chunk_name == png_IDAT)
\r
814 if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
\r
815 || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
\r
816 png_benign_error(png_ptr, ".Too many IDATs found");
\r
818 png_handle_unknown(png_ptr, info_ptr, length, keep);
\r
819 if (chunk_name == png_PLTE)
\r
820 png_ptr->mode |= PNG_HAVE_PLTE;
\r
824 else if (chunk_name == png_IDAT)
\r
826 /* Zero length IDATs are legal after the last IDAT has been
\r
827 * read, but not after other chunks have been read. 1.6 does not
\r
828 * always read all the deflate data; specifically it cannot be relied
\r
829 * upon to read the Adler32 at the end. If it doesn't ignore IDAT
\r
830 * chunks which are longer than zero as well:
\r
832 if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
\r
833 || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
\r
834 png_benign_error(png_ptr, "..Too many IDATs found");
\r
836 png_crc_finish(png_ptr, length);
\r
838 else if (chunk_name == png_PLTE)
\r
839 png_handle_PLTE(png_ptr, info_ptr, length);
\r
841 #ifdef PNG_READ_bKGD_SUPPORTED
\r
842 else if (chunk_name == png_bKGD)
\r
843 png_handle_bKGD(png_ptr, info_ptr, length);
\r
846 #ifdef PNG_READ_cHRM_SUPPORTED
\r
847 else if (chunk_name == png_cHRM)
\r
848 png_handle_cHRM(png_ptr, info_ptr, length);
\r
851 #ifdef PNG_READ_eXIf_SUPPORTED
\r
852 else if (chunk_name == png_eXIf)
\r
853 png_handle_eXIf(png_ptr, info_ptr, length);
\r
856 #ifdef PNG_READ_gAMA_SUPPORTED
\r
857 else if (chunk_name == png_gAMA)
\r
858 png_handle_gAMA(png_ptr, info_ptr, length);
\r
861 #ifdef PNG_READ_hIST_SUPPORTED
\r
862 else if (chunk_name == png_hIST)
\r
863 png_handle_hIST(png_ptr, info_ptr, length);
\r
866 #ifdef PNG_READ_oFFs_SUPPORTED
\r
867 else if (chunk_name == png_oFFs)
\r
868 png_handle_oFFs(png_ptr, info_ptr, length);
\r
871 #ifdef PNG_READ_pCAL_SUPPORTED
\r
872 else if (chunk_name == png_pCAL)
\r
873 png_handle_pCAL(png_ptr, info_ptr, length);
\r
876 #ifdef PNG_READ_sCAL_SUPPORTED
\r
877 else if (chunk_name == png_sCAL)
\r
878 png_handle_sCAL(png_ptr, info_ptr, length);
\r
881 #ifdef PNG_READ_pHYs_SUPPORTED
\r
882 else if (chunk_name == png_pHYs)
\r
883 png_handle_pHYs(png_ptr, info_ptr, length);
\r
886 #ifdef PNG_READ_sBIT_SUPPORTED
\r
887 else if (chunk_name == png_sBIT)
\r
888 png_handle_sBIT(png_ptr, info_ptr, length);
\r
891 #ifdef PNG_READ_sRGB_SUPPORTED
\r
892 else if (chunk_name == png_sRGB)
\r
893 png_handle_sRGB(png_ptr, info_ptr, length);
\r
896 #ifdef PNG_READ_iCCP_SUPPORTED
\r
897 else if (chunk_name == png_iCCP)
\r
898 png_handle_iCCP(png_ptr, info_ptr, length);
\r
901 #ifdef PNG_READ_sPLT_SUPPORTED
\r
902 else if (chunk_name == png_sPLT)
\r
903 png_handle_sPLT(png_ptr, info_ptr, length);
\r
906 #ifdef PNG_READ_tEXt_SUPPORTED
\r
907 else if (chunk_name == png_tEXt)
\r
908 png_handle_tEXt(png_ptr, info_ptr, length);
\r
911 #ifdef PNG_READ_tIME_SUPPORTED
\r
912 else if (chunk_name == png_tIME)
\r
913 png_handle_tIME(png_ptr, info_ptr, length);
\r
916 #ifdef PNG_READ_tRNS_SUPPORTED
\r
917 else if (chunk_name == png_tRNS)
\r
918 png_handle_tRNS(png_ptr, info_ptr, length);
\r
921 #ifdef PNG_READ_zTXt_SUPPORTED
\r
922 else if (chunk_name == png_zTXt)
\r
923 png_handle_zTXt(png_ptr, info_ptr, length);
\r
926 #ifdef PNG_READ_iTXt_SUPPORTED
\r
927 else if (chunk_name == png_iTXt)
\r
928 png_handle_iTXt(png_ptr, info_ptr, length);
\r
932 png_handle_unknown(png_ptr, info_ptr, length,
\r
933 PNG_HANDLE_CHUNK_AS_DEFAULT);
\r
934 } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
\r
936 #endif /* SEQUENTIAL_READ */
\r
938 /* Free all memory used in the read struct */
\r
940 png_read_destroy(png_structrp png_ptr)
\r
942 png_debug(1, "in png_read_destroy");
\r
944 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
945 png_destroy_gamma_table(png_ptr);
\r
948 png_free(png_ptr, png_ptr->big_row_buf);
\r
949 png_ptr->big_row_buf = NULL;
\r
950 png_free(png_ptr, png_ptr->big_prev_row);
\r
951 png_ptr->big_prev_row = NULL;
\r
952 png_free(png_ptr, png_ptr->read_buffer);
\r
953 png_ptr->read_buffer = NULL;
\r
955 #ifdef PNG_READ_QUANTIZE_SUPPORTED
\r
956 png_free(png_ptr, png_ptr->palette_lookup);
\r
957 png_ptr->palette_lookup = NULL;
\r
958 png_free(png_ptr, png_ptr->quantize_index);
\r
959 png_ptr->quantize_index = NULL;
\r
962 if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
\r
964 png_zfree(png_ptr, png_ptr->palette);
\r
965 png_ptr->palette = NULL;
\r
967 png_ptr->free_me &= ~PNG_FREE_PLTE;
\r
969 #if defined(PNG_tRNS_SUPPORTED) || \
\r
970 defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
\r
971 if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
\r
973 png_free(png_ptr, png_ptr->trans_alpha);
\r
974 png_ptr->trans_alpha = NULL;
\r
976 png_ptr->free_me &= ~PNG_FREE_TRNS;
\r
979 inflateEnd(&png_ptr->zstream);
\r
981 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
\r
982 png_free(png_ptr, png_ptr->save_buffer);
\r
983 png_ptr->save_buffer = NULL;
\r
986 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
\r
987 defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
\r
988 png_free(png_ptr, png_ptr->unknown_chunk.data);
\r
989 png_ptr->unknown_chunk.data = NULL;
\r
992 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
\r
993 png_free(png_ptr, png_ptr->chunk_list);
\r
994 png_ptr->chunk_list = NULL;
\r
997 #if defined(PNG_READ_EXPAND_SUPPORTED) && \
\r
998 defined(PNG_ARM_NEON_IMPLEMENTATION)
\r
999 png_free(png_ptr, png_ptr->riffled_palette);
\r
1000 png_ptr->riffled_palette = NULL;
\r
1003 /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
\r
1004 * callbacks are still set at this point. They are required to complete the
\r
1005 * destruction of the png_struct itself.
\r
1009 /* Free all memory used by the read */
\r
1011 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
\r
1012 png_infopp end_info_ptr_ptr)
\r
1014 png_structrp png_ptr = NULL;
\r
1016 png_debug(1, "in png_destroy_read_struct");
\r
1018 if (png_ptr_ptr != NULL)
\r
1019 png_ptr = *png_ptr_ptr;
\r
1021 if (png_ptr == NULL)
\r
1024 /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
\r
1025 * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API.
\r
1026 * The extra was, apparently, unnecessary yet this hides memory leak bugs.
\r
1028 png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
\r
1029 png_destroy_info_struct(png_ptr, info_ptr_ptr);
\r
1031 *png_ptr_ptr = NULL;
\r
1032 png_read_destroy(png_ptr);
\r
1033 png_destroy_png_struct(png_ptr);
\r
1037 png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
\r
1039 if (png_ptr == NULL)
\r
1042 png_ptr->read_row_fn = read_row_fn;
\r
1046 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
\r
1047 #ifdef PNG_INFO_IMAGE_SUPPORTED
\r
1049 png_read_png(png_structrp png_ptr, png_inforp info_ptr,
\r
1050 int transforms, voidp params)
\r
1052 if (png_ptr == NULL || info_ptr == NULL)
\r
1055 /* png_read_info() gives us all of the information from the
\r
1056 * PNG file before the first IDAT (image data chunk).
\r
1058 png_read_info(png_ptr, info_ptr);
\r
1059 if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
\r
1060 png_error(png_ptr, "Image is too high to process with png_read_png()");
\r
1062 /* -------------- image transformations start here ------------------- */
\r
1063 /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
\r
1064 * is not implemented. This will only happen in de-configured (non-default)
\r
1065 * libpng builds. The results can be unexpected - png_read_png may return
\r
1066 * short or mal-formed rows because the transform is skipped.
\r
1069 /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
\r
1071 if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
\r
1072 /* Added at libpng-1.5.4. "strip_16" produces the same result that it
\r
1073 * did in earlier versions, while "scale_16" is now more accurate.
\r
1075 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
\r
1076 png_set_scale_16(png_ptr);
\r
1078 png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
\r
1081 /* If both SCALE and STRIP are required pngrtran will effectively cancel the
\r
1082 * latter by doing SCALE first. This is ok and allows apps not to check for
\r
1083 * which is supported to get the right answer.
\r
1085 if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
\r
1086 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
\r
1087 png_set_strip_16(png_ptr);
\r
1089 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
\r
1092 /* Strip alpha bytes from the input data without combining with
\r
1093 * the background (not recommended).
\r
1095 if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
\r
1096 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
\r
1097 png_set_strip_alpha(png_ptr);
\r
1099 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
\r
1102 /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
\r
1103 * byte into separate bytes (useful for paletted and grayscale images).
\r
1105 if ((transforms & PNG_TRANSFORM_PACKING) != 0)
\r
1106 #ifdef PNG_READ_PACK_SUPPORTED
\r
1107 png_set_packing(png_ptr);
\r
1109 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
\r
1112 /* Change the order of packed pixels to least significant bit first
\r
1113 * (not useful if you are using png_set_packing).
\r
1115 if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
\r
1116 #ifdef PNG_READ_PACKSWAP_SUPPORTED
\r
1117 png_set_packswap(png_ptr);
\r
1119 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
\r
1122 /* Expand paletted colors into true RGB triplets
\r
1123 * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
\r
1124 * Expand paletted or RGB images with transparency to full alpha
\r
1125 * channels so the data will be available as RGBA quartets.
\r
1127 if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
\r
1128 #ifdef PNG_READ_EXPAND_SUPPORTED
\r
1129 png_set_expand(png_ptr);
\r
1131 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
\r
1134 /* We don't handle background color or gamma transformation or quantizing.
\r
1137 /* Invert monochrome files to have 0 as white and 1 as black
\r
1139 if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
\r
1140 #ifdef PNG_READ_INVERT_SUPPORTED
\r
1141 png_set_invert_mono(png_ptr);
\r
1143 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
\r
1146 /* If you want to shift the pixel values from the range [0,255] or
\r
1147 * [0,65535] to the original [0,7] or [0,31], or whatever range the
\r
1148 * colors were originally in:
\r
1150 if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
\r
1151 #ifdef PNG_READ_SHIFT_SUPPORTED
\r
1152 if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
\r
1153 png_set_shift(png_ptr, &info_ptr->sig_bit);
\r
1155 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
\r
1158 /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
\r
1159 if ((transforms & PNG_TRANSFORM_BGR) != 0)
\r
1160 #ifdef PNG_READ_BGR_SUPPORTED
\r
1161 png_set_bgr(png_ptr);
\r
1163 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
\r
1166 /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
\r
1167 if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
\r
1168 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
\r
1169 png_set_swap_alpha(png_ptr);
\r
1171 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
\r
1174 /* Swap bytes of 16-bit files to least significant byte first */
\r
1175 if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
\r
1176 #ifdef PNG_READ_SWAP_SUPPORTED
\r
1177 png_set_swap(png_ptr);
\r
1179 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
\r
1182 /* Added at libpng-1.2.41 */
\r
1183 /* Invert the alpha channel from opacity to transparency */
\r
1184 if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
\r
1185 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
\r
1186 png_set_invert_alpha(png_ptr);
\r
1188 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
\r
1191 /* Added at libpng-1.2.41 */
\r
1192 /* Expand grayscale image to RGB */
\r
1193 if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
\r
1194 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
\r
1195 png_set_gray_to_rgb(png_ptr);
\r
1197 png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
\r
1200 /* Added at libpng-1.5.4 */
\r
1201 if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
\r
1202 #ifdef PNG_READ_EXPAND_16_SUPPORTED
\r
1203 png_set_expand_16(png_ptr);
\r
1205 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
\r
1208 /* We don't handle adding filler bytes */
\r
1210 /* We use png_read_image and rely on that for interlace handling, but we also
\r
1211 * call png_read_update_info therefore must turn on interlace handling now:
\r
1213 (void)png_set_interlace_handling(png_ptr);
\r
1215 /* Optional call to gamma correct and add the background to the palette
\r
1216 * and update info structure. REQUIRED if you are expecting libpng to
\r
1217 * update the palette for you (i.e., you selected such a transform above).
\r
1219 png_read_update_info(png_ptr, info_ptr);
\r
1221 /* -------------- image transformations end here ------------------- */
\r
1223 png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
\r
1224 if (info_ptr->row_pointers == NULL)
\r
1228 info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
\r
1229 info_ptr->height * (sizeof (png_bytep))));
\r
1231 for (iptr=0; iptr<info_ptr->height; iptr++)
\r
1232 info_ptr->row_pointers[iptr] = NULL;
\r
1234 info_ptr->free_me |= PNG_FREE_ROWS;
\r
1236 for (iptr = 0; iptr < info_ptr->height; iptr++)
\r
1237 info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
\r
1238 png_malloc(png_ptr, info_ptr->rowbytes));
\r
1241 png_read_image(png_ptr, info_ptr->row_pointers);
\r
1242 info_ptr->valid |= PNG_INFO_IDAT;
\r
1244 /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
\r
1245 png_read_end(png_ptr, info_ptr);
\r
1247 PNG_UNUSED(params)
\r
1249 #endif /* INFO_IMAGE */
\r
1250 #endif /* SEQUENTIAL_READ */
\r
1252 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
\r
1253 /* SIMPLIFIED READ
\r
1255 * This code currently relies on the sequential reader, though it could easily
\r
1256 * be made to work with the progressive one.
\r
1258 /* Arguments to png_image_finish_read: */
\r
1260 /* Encoding of PNG data (used by the color-map code) */
\r
1261 # define P_NOTSET 0 /* File encoding not yet known */
\r
1262 # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
\r
1263 # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
\r
1264 # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
\r
1265 # define P_LINEAR8 4 /* 8-bit linear: only from a file value */
\r
1267 /* Color-map processing: after libpng has run on the PNG image further
\r
1268 * processing may be needed to convert the data to color-map indices.
\r
1270 #define PNG_CMAP_NONE 0
\r
1271 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
\r
1272 #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
\r
1273 #define PNG_CMAP_RGB 3 /* Process RGB data */
\r
1274 #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
\r
1276 /* The following document where the background is for each processing case. */
\r
1277 #define PNG_CMAP_NONE_BACKGROUND 256
\r
1278 #define PNG_CMAP_GA_BACKGROUND 231
\r
1279 #define PNG_CMAP_TRANS_BACKGROUND 254
\r
1280 #define PNG_CMAP_RGB_BACKGROUND 256
\r
1281 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
\r
1288 png_int_32 row_stride;
\r
1289 png_voidp colormap;
\r
1290 png_const_colorp background;
\r
1291 /* Local variables: */
\r
1292 png_voidp local_row;
\r
1293 png_voidp first_row;
\r
1294 ptrdiff_t row_bytes; /* step between rows */
\r
1295 int file_encoding; /* E_ values above */
\r
1296 png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
\r
1297 int colormap_processing; /* PNG_CMAP_ values above */
\r
1298 } png_image_read_control;
\r
1300 /* Do all the *safe* initialization - 'safe' means that png_error won't be
\r
1301 * called, so setting up the jmp_buf is not required. This means that anything
\r
1302 * called from here must *not* call png_malloc - it has to call png_malloc_warn
\r
1303 * instead so that control is returned safely back to this routine.
\r
1306 png_image_read_init(png_imagep image)
\r
1308 if (image->opaque == NULL)
\r
1310 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
\r
1311 png_safe_error, png_safe_warning);
\r
1313 /* And set the rest of the structure to NULL to ensure that the various
\r
1314 * fields are consistent.
\r
1316 memset(image, 0, (sizeof *image));
\r
1317 image->version = PNG_IMAGE_VERSION;
\r
1319 if (png_ptr != NULL)
\r
1321 png_infop info_ptr = png_create_info_struct(png_ptr);
\r
1323 if (info_ptr != NULL)
\r
1325 png_controlp control = png_voidcast(png_controlp,
\r
1326 png_malloc_warn(png_ptr, (sizeof *control)));
\r
1328 if (control != NULL)
\r
1330 memset(control, 0, (sizeof *control));
\r
1332 control->png_ptr = png_ptr;
\r
1333 control->info_ptr = info_ptr;
\r
1334 control->for_write = 0;
\r
1336 image->opaque = control;
\r
1340 /* Error clean up */
\r
1341 png_destroy_info_struct(png_ptr, &info_ptr);
\r
1344 png_destroy_read_struct(&png_ptr, NULL, NULL);
\r
1347 return png_image_error(image, "png_image_read: out of memory");
\r
1350 return png_image_error(image, "png_image_read: opaque pointer not NULL");
\r
1353 /* Utility to find the base format of a PNG file from a png_struct. */
\r
1354 static png_uint_32
\r
1355 png_image_format(png_structrp png_ptr)
\r
1357 png_uint_32 format = 0;
\r
1359 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
\r
1360 format |= PNG_FORMAT_FLAG_COLOR;
\r
1362 if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
\r
1363 format |= PNG_FORMAT_FLAG_ALPHA;
\r
1365 /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
\r
1366 * sets the png_struct fields; that's all we are interested in here. The
\r
1367 * precise interaction with an app call to png_set_tRNS and PNG file reading
\r
1370 else if (png_ptr->num_trans > 0)
\r
1371 format |= PNG_FORMAT_FLAG_ALPHA;
\r
1373 if (png_ptr->bit_depth == 16)
\r
1374 format |= PNG_FORMAT_FLAG_LINEAR;
\r
1376 if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
\r
1377 format |= PNG_FORMAT_FLAG_COLORMAP;
\r
1382 /* Is the given gamma significantly different from sRGB? The test is the same
\r
1383 * one used in pngrtran.c when deciding whether to do gamma correction. The
\r
1384 * arithmetic optimizes the division by using the fact that the inverse of the
\r
1385 * file sRGB gamma is 2.2
\r
1388 png_gamma_not_sRGB(png_fixed_point g)
\r
1392 /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
\r
1396 return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
\r
1402 /* Do the main body of a 'png_image_begin_read' function; read the PNG file
\r
1403 * header and fill in all the information. This is executed in a safe context,
\r
1404 * unlike the init routine above.
\r
1407 png_image_read_header(png_voidp argument)
\r
1409 png_imagep image = png_voidcast(png_imagep, argument);
\r
1410 png_structrp png_ptr = image->opaque->png_ptr;
\r
1411 png_inforp info_ptr = image->opaque->info_ptr;
\r
1413 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
\r
1414 png_set_benign_errors(png_ptr, 1/*warn*/);
\r
1416 png_read_info(png_ptr, info_ptr);
\r
1418 /* Do this the fast way; just read directly out of png_struct. */
\r
1419 image->width = png_ptr->width;
\r
1420 image->height = png_ptr->height;
\r
1423 png_uint_32 format = png_image_format(png_ptr);
\r
1425 image->format = format;
\r
1427 #ifdef PNG_COLORSPACE_SUPPORTED
\r
1428 /* Does the colorspace match sRGB? If there is no color endpoint
\r
1429 * (colorant) information assume yes, otherwise require the
\r
1430 * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
\r
1431 * colorspace has been determined to be invalid ignore it.
\r
1433 if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
\r
1434 & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
\r
1435 PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
\r
1436 image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
\r
1440 /* We need the maximum number of entries regardless of the format the
\r
1441 * application sets here.
\r
1444 png_uint_32 cmap_entries;
\r
1446 switch (png_ptr->color_type)
\r
1448 case PNG_COLOR_TYPE_GRAY:
\r
1449 cmap_entries = 1U << png_ptr->bit_depth;
\r
1452 case PNG_COLOR_TYPE_PALETTE:
\r
1453 cmap_entries = (png_uint_32)png_ptr->num_palette;
\r
1457 cmap_entries = 256;
\r
1461 if (cmap_entries > 256)
\r
1462 cmap_entries = 256;
\r
1464 image->colormap_entries = cmap_entries;
\r
1470 #ifdef PNG_STDIO_SUPPORTED
\r
1472 png_image_begin_read_from_stdio(png_imagep image, FILE* file)
\r
1474 if (image != NULL && image->version == PNG_IMAGE_VERSION)
\r
1478 if (png_image_read_init(image) != 0)
\r
1480 /* This is slightly evil, but png_init_io doesn't do anything other
\r
1481 * than this and we haven't changed the standard IO functions so
\r
1482 * this saves a 'safe' function.
\r
1484 image->opaque->png_ptr->io_ptr = file;
\r
1485 return png_safe_execute(image, png_image_read_header, image);
\r
1490 return png_image_error(image,
\r
1491 "png_image_begin_read_from_stdio: invalid argument");
\r
1494 else if (image != NULL)
\r
1495 return png_image_error(image,
\r
1496 "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
\r
1502 png_image_begin_read_from_file(png_imagep image, const char *file_name)
\r
1504 if (image != NULL && image->version == PNG_IMAGE_VERSION)
\r
1506 if (file_name != NULL)
\r
1508 FILE *fp = fopen(file_name, "rb");
\r
1512 if (png_image_read_init(image) != 0)
\r
1514 image->opaque->png_ptr->io_ptr = fp;
\r
1515 image->opaque->owned_file = 1;
\r
1516 return png_safe_execute(image, png_image_read_header, image);
\r
1519 /* Clean up: just the opened file. */
\r
1524 return png_image_error(image, strerror(errno));
\r
1528 return png_image_error(image,
\r
1529 "png_image_begin_read_from_file: invalid argument");
\r
1532 else if (image != NULL)
\r
1533 return png_image_error(image,
\r
1534 "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
\r
1538 #endif /* STDIO */
\r
1540 static void PNGCBAPI
\r
1541 png_image_memory_read(png_structp png_ptr, png_bytep out, size_t need)
\r
1543 if (png_ptr != NULL)
\r
1545 png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
\r
1546 if (image != NULL)
\r
1548 png_controlp cp = image->opaque;
\r
1551 png_const_bytep memory = cp->memory;
\r
1552 size_t size = cp->size;
\r
1554 if (memory != NULL && size >= need)
\r
1556 memcpy(out, memory, need);
\r
1557 cp->memory = memory + need;
\r
1558 cp->size = size - need;
\r
1562 png_error(png_ptr, "read beyond end of data");
\r
1566 png_error(png_ptr, "invalid memory read");
\r
1570 int PNGAPI png_image_begin_read_from_memory(png_imagep image,
\r
1571 png_const_voidp memory, size_t size)
\r
1573 if (image != NULL && image->version == PNG_IMAGE_VERSION)
\r
1575 if (memory != NULL && size > 0)
\r
1577 if (png_image_read_init(image) != 0)
\r
1579 /* Now set the IO functions to read from the memory buffer and
\r
1580 * store it into io_ptr. Again do this in-place to avoid calling a
\r
1581 * libpng function that requires error handling.
\r
1583 image->opaque->memory = png_voidcast(png_const_bytep, memory);
\r
1584 image->opaque->size = size;
\r
1585 image->opaque->png_ptr->io_ptr = image;
\r
1586 image->opaque->png_ptr->read_data_fn = png_image_memory_read;
\r
1588 return png_safe_execute(image, png_image_read_header, image);
\r
1593 return png_image_error(image,
\r
1594 "png_image_begin_read_from_memory: invalid argument");
\r
1597 else if (image != NULL)
\r
1598 return png_image_error(image,
\r
1599 "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
\r
1604 /* Utility function to skip chunks that are not used by the simplified image
\r
1605 * read functions and an appropriate macro to call it.
\r
1607 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
\r
1609 png_image_skip_unused_chunks(png_structrp png_ptr)
\r
1611 /* Prepare the reader to ignore all recognized chunks whose data will not
\r
1612 * be used, i.e., all chunks recognized by libpng except for those
\r
1613 * involved in basic image reading:
\r
1615 * IHDR, PLTE, IDAT, IEND
\r
1617 * Or image data handling:
\r
1619 * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
\r
1621 * This provides a small performance improvement and eliminates any
\r
1622 * potential vulnerability to security problems in the unused chunks.
\r
1624 * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
\r
1625 * too. This allows the simplified API to be compiled without iCCP support,
\r
1626 * however if the support is there the chunk is still checked to detect
\r
1627 * errors (which are unfortunately quite common.)
\r
1630 static const png_byte chunks_to_process[] = {
\r
1631 98, 75, 71, 68, '\0', /* bKGD */
\r
1632 99, 72, 82, 77, '\0', /* cHRM */
\r
1633 103, 65, 77, 65, '\0', /* gAMA */
\r
1634 # ifdef PNG_READ_iCCP_SUPPORTED
\r
1635 105, 67, 67, 80, '\0', /* iCCP */
\r
1637 115, 66, 73, 84, '\0', /* sBIT */
\r
1638 115, 82, 71, 66, '\0', /* sRGB */
\r
1641 /* Ignore unknown chunks and all other chunks except for the
\r
1642 * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
\r
1644 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
\r
1647 /* But do not ignore image data handling chunks */
\r
1648 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
\r
1649 chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
\r
1653 # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
\r
1655 # define PNG_SKIP_CHUNKS(p) ((void)0)
\r
1656 #endif /* HANDLE_AS_UNKNOWN */
\r
1658 /* The following macro gives the exact rounded answer for all values in the
\r
1659 * range 0..255 (it actually divides by 51.2, but the rounding still generates
\r
1660 * the correct numbers 0..5
\r
1662 #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
\r
1664 /* Utility functions to make particular color-maps */
\r
1666 set_file_encoding(png_image_read_control *display)
\r
1668 png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
\r
1669 if (png_gamma_significant(g) != 0)
\r
1671 if (png_gamma_not_sRGB(g) != 0)
\r
1673 display->file_encoding = P_FILE;
\r
1674 display->gamma_to_linear = png_reciprocal(g);
\r
1678 display->file_encoding = P_sRGB;
\r
1682 display->file_encoding = P_LINEAR8;
\r
1685 static unsigned int
\r
1686 decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
\r
1688 if (encoding == P_FILE) /* double check */
\r
1689 encoding = display->file_encoding;
\r
1691 if (encoding == P_NOTSET) /* must be the file encoding */
\r
1693 set_file_encoding(display);
\r
1694 encoding = display->file_encoding;
\r
1700 value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
\r
1704 value = png_sRGB_table[value];
\r
1716 png_error(display->image->opaque->png_ptr,
\r
1717 "unexpected encoding (internal error)");
\r
1724 static png_uint_32
\r
1725 png_colormap_compose(png_image_read_control *display,
\r
1726 png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
\r
1727 png_uint_32 background, int encoding)
\r
1729 /* The file value is composed on the background, the background has the given
\r
1730 * encoding and so does the result, the file is encoded with P_FILE and the
\r
1731 * file and alpha are 8-bit values. The (output) encoding will always be
\r
1732 * P_LINEAR or P_sRGB.
\r
1734 png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
\r
1735 png_uint_32 b = decode_gamma(display, background, encoding);
\r
1737 /* The alpha is always an 8-bit value (it comes from the palette), the value
\r
1738 * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
\r
1740 f = f * alpha + b * (255-alpha);
\r
1742 if (encoding == P_LINEAR)
\r
1744 /* Scale to 65535; divide by 255, approximately (in fact this is extremely
\r
1745 * accurate, it divides by 255.00000005937181414556, with no overflow.)
\r
1747 f *= 257; /* Now scaled by 65535 */
\r
1749 f = (f+32768) >> 16;
\r
1753 f = PNG_sRGB_FROM_LINEAR(f);
\r
1758 /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
\r
1762 png_create_colormap_entry(png_image_read_control *display,
\r
1763 png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
\r
1764 png_uint_32 alpha, int encoding)
\r
1766 png_imagep image = display->image;
\r
1767 int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
\r
1768 P_LINEAR : P_sRGB;
\r
1769 int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
\r
1770 (red != green || green != blue);
\r
1773 png_error(image->opaque->png_ptr, "color-map index out of range");
\r
1775 /* Update the cache with whether the file gamma is significantly different
\r
1778 if (encoding == P_FILE)
\r
1780 if (display->file_encoding == P_NOTSET)
\r
1781 set_file_encoding(display);
\r
1783 /* Note that the cached value may be P_FILE too, but if it is then the
\r
1784 * gamma_to_linear member has been set.
\r
1786 encoding = display->file_encoding;
\r
1789 if (encoding == P_FILE)
\r
1791 png_fixed_point g = display->gamma_to_linear;
\r
1793 red = png_gamma_16bit_correct(red*257, g);
\r
1794 green = png_gamma_16bit_correct(green*257, g);
\r
1795 blue = png_gamma_16bit_correct(blue*257, g);
\r
1797 if (convert_to_Y != 0 || output_encoding == P_LINEAR)
\r
1800 encoding = P_LINEAR;
\r
1805 red = PNG_sRGB_FROM_LINEAR(red * 255);
\r
1806 green = PNG_sRGB_FROM_LINEAR(green * 255);
\r
1807 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
\r
1808 encoding = P_sRGB;
\r
1812 else if (encoding == P_LINEAR8)
\r
1814 /* This encoding occurs quite frequently in test cases because PngSuite
\r
1815 * includes a gAMA 1.0 chunk with most images.
\r
1821 encoding = P_LINEAR;
\r
1824 else if (encoding == P_sRGB &&
\r
1825 (convert_to_Y != 0 || output_encoding == P_LINEAR))
\r
1827 /* The values are 8-bit sRGB values, but must be converted to 16-bit
\r
1830 red = png_sRGB_table[red];
\r
1831 green = png_sRGB_table[green];
\r
1832 blue = png_sRGB_table[blue];
\r
1834 encoding = P_LINEAR;
\r
1837 /* This is set if the color isn't gray but the output is. */
\r
1838 if (encoding == P_LINEAR)
\r
1840 if (convert_to_Y != 0)
\r
1842 /* NOTE: these values are copied from png_do_rgb_to_gray */
\r
1843 png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green +
\r
1844 (png_uint_32)2366 * blue;
\r
1846 if (output_encoding == P_LINEAR)
\r
1847 y = (y + 16384) >> 15;
\r
1851 /* y is scaled by 32768, we need it scaled by 255: */
\r
1852 y = (y + 128) >> 8;
\r
1854 y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
\r
1855 alpha = PNG_DIV257(alpha);
\r
1856 encoding = P_sRGB;
\r
1859 blue = red = green = y;
\r
1862 else if (output_encoding == P_sRGB)
\r
1864 red = PNG_sRGB_FROM_LINEAR(red * 255);
\r
1865 green = PNG_sRGB_FROM_LINEAR(green * 255);
\r
1866 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
\r
1867 alpha = PNG_DIV257(alpha);
\r
1868 encoding = P_sRGB;
\r
1872 if (encoding != output_encoding)
\r
1873 png_error(image->opaque->png_ptr, "bad encoding (internal error)");
\r
1875 /* Store the value. */
\r
1877 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
\r
1878 int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
\r
1879 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
\r
1883 # ifdef PNG_FORMAT_BGR_SUPPORTED
\r
1884 int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
\r
1889 if (output_encoding == P_LINEAR)
\r
1891 png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
\r
1893 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
\r
1895 /* The linear 16-bit values must be pre-multiplied by the alpha channel
\r
1896 * value, if less than 65535 (this is, effectively, composite on black
\r
1897 * if the alpha channel is removed.)
\r
1899 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
\r
1902 entry[afirst ? 0 : 3] = (png_uint_16)alpha;
\r
1906 if (alpha < 65535)
\r
1910 blue = (blue * alpha + 32767U)/65535U;
\r
1911 green = (green * alpha + 32767U)/65535U;
\r
1912 red = (red * alpha + 32767U)/65535U;
\r
1916 red = green = blue = 0;
\r
1918 entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
\r
1919 entry[afirst + 1] = (png_uint_16)green;
\r
1920 entry[afirst + bgr] = (png_uint_16)red;
\r
1924 entry[1 ^ afirst] = (png_uint_16)alpha;
\r
1928 if (alpha < 65535)
\r
1931 green = (green * alpha + 32767U)/65535U;
\r
1936 entry[afirst] = (png_uint_16)green;
\r
1944 else /* output encoding is P_sRGB */
\r
1946 png_bytep entry = png_voidcast(png_bytep, display->colormap);
\r
1948 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
\r
1950 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
\r
1953 entry[afirst ? 0 : 3] = (png_byte)alpha;
\r
1956 entry[afirst + (2 ^ bgr)] = (png_byte)blue;
\r
1957 entry[afirst + 1] = (png_byte)green;
\r
1958 entry[afirst + bgr] = (png_byte)red;
\r
1962 entry[1 ^ afirst] = (png_byte)alpha;
\r
1965 entry[afirst] = (png_byte)green;
\r
1983 make_gray_file_colormap(png_image_read_control *display)
\r
1987 for (i=0; i<256; ++i)
\r
1988 png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
\r
1994 make_gray_colormap(png_image_read_control *display)
\r
1998 for (i=0; i<256; ++i)
\r
1999 png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
\r
2003 #define PNG_GRAY_COLORMAP_ENTRIES 256
\r
2006 make_ga_colormap(png_image_read_control *display)
\r
2008 unsigned int i, a;
\r
2010 /* Alpha is retained, the output will be a color-map with entries
\r
2011 * selected by six levels of alpha. One transparent entry, 6 gray
\r
2012 * levels for all the intermediate alpha values, leaving 230 entries
\r
2013 * for the opaque grays. The color-map entries are the six values
\r
2014 * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
\r
2017 * if (alpha > 229) // opaque
\r
2019 * // The 231 entries are selected to make the math below work:
\r
2021 * entry = (231 * gray + 128) >> 8;
\r
2023 * else if (alpha < 26) // transparent
\r
2028 * else // partially opaque
\r
2030 * base = 226 + 6 * PNG_DIV51(alpha);
\r
2031 * entry = PNG_DIV51(gray);
\r
2037 unsigned int gray = (i * 256 + 115) / 231;
\r
2038 png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
\r
2041 /* 255 is used here for the component values for consistency with the code
\r
2042 * that undoes premultiplication in pngwrite.c.
\r
2044 png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
\r
2046 for (a=1; a<5; ++a)
\r
2050 for (g=0; g<6; ++g)
\r
2051 png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
\r
2058 #define PNG_GA_COLORMAP_ENTRIES 256
\r
2061 make_rgb_colormap(png_image_read_control *display)
\r
2063 unsigned int i, r;
\r
2065 /* Build a 6x6x6 opaque RGB cube */
\r
2066 for (i=r=0; r<6; ++r)
\r
2070 for (g=0; g<6; ++g)
\r
2074 for (b=0; b<6; ++b)
\r
2075 png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
\r
2083 #define PNG_RGB_COLORMAP_ENTRIES 216
\r
2085 /* Return a palette index to the above palette given three 8-bit sRGB values. */
\r
2086 #define PNG_RGB_INDEX(r,g,b) \
\r
2087 ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
\r
2090 png_image_read_colormap(png_voidp argument)
\r
2092 png_image_read_control *display =
\r
2093 png_voidcast(png_image_read_control*, argument);
\r
2094 png_imagep image = display->image;
\r
2096 png_structrp png_ptr = image->opaque->png_ptr;
\r
2097 png_uint_32 output_format = image->format;
\r
2098 int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
\r
2099 P_LINEAR : P_sRGB;
\r
2101 unsigned int cmap_entries;
\r
2102 unsigned int output_processing; /* Output processing option */
\r
2103 unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
\r
2105 /* Background information; the background color and the index of this color
\r
2106 * in the color-map if it exists (else 256).
\r
2108 unsigned int background_index = 256;
\r
2109 png_uint_32 back_r, back_g, back_b;
\r
2111 /* Flags to accumulate things that need to be done to the input. */
\r
2112 int expand_tRNS = 0;
\r
2114 /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
\r
2115 * very difficult to do, the results look awful, and it is difficult to see
\r
2116 * what possible use it is because the application can't control the
\r
2119 if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
\r
2120 png_ptr->num_trans > 0) /* alpha in input */ &&
\r
2121 ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
\r
2123 if (output_encoding == P_LINEAR) /* compose on black */
\r
2124 back_b = back_g = back_r = 0;
\r
2126 else if (display->background == NULL /* no way to remove it */)
\r
2127 png_error(png_ptr,
\r
2128 "background color must be supplied to remove alpha/transparency");
\r
2130 /* Get a copy of the background color (this avoids repeating the checks
\r
2131 * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
\r
2136 back_g = display->background->green;
\r
2137 if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
\r
2139 back_r = display->background->red;
\r
2140 back_b = display->background->blue;
\r
2143 back_b = back_r = back_g;
\r
2147 else if (output_encoding == P_LINEAR)
\r
2148 back_b = back_r = back_g = 65535;
\r
2151 back_b = back_r = back_g = 255;
\r
2153 /* Default the input file gamma if required - this is necessary because
\r
2154 * libpng assumes that if no gamma information is present the data is in the
\r
2155 * output format, but the simplified API deduces the gamma from the input
\r
2158 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
\r
2160 /* Do this directly, not using the png_colorspace functions, to ensure
\r
2161 * that it happens even if the colorspace is invalid (though probably if
\r
2162 * it is the setting will be ignored) Note that the same thing can be
\r
2163 * achieved at the application interface with png_set_gAMA.
\r
2165 if (png_ptr->bit_depth == 16 &&
\r
2166 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
\r
2167 png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
\r
2170 png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
\r
2172 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
\r
2175 /* Decide what to do based on the PNG color type of the input data. The
\r
2176 * utility function png_create_colormap_entry deals with most aspects of the
\r
2177 * output transformations; this code works out how to produce bytes of
\r
2178 * color-map entries from the original format.
\r
2180 switch (png_ptr->color_type)
\r
2182 case PNG_COLOR_TYPE_GRAY:
\r
2183 if (png_ptr->bit_depth <= 8)
\r
2185 /* There at most 256 colors in the output, regardless of
\r
2188 unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
\r
2190 cmap_entries = 1U << png_ptr->bit_depth;
\r
2191 if (cmap_entries > image->colormap_entries)
\r
2192 png_error(png_ptr, "gray[8] color-map: too few entries");
\r
2194 step = 255 / (cmap_entries - 1);
\r
2195 output_processing = PNG_CMAP_NONE;
\r
2197 /* If there is a tRNS chunk then this either selects a transparent
\r
2198 * value or, if the output has no alpha, the background color.
\r
2200 if (png_ptr->num_trans > 0)
\r
2202 trans = png_ptr->trans_color.gray;
\r
2204 if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
\r
2205 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
\r
2208 /* png_create_colormap_entry just takes an RGBA and writes the
\r
2209 * corresponding color-map entry using the format from 'image',
\r
2210 * including the required conversion to sRGB or linear as
\r
2211 * appropriate. The input values are always either sRGB (if the
\r
2212 * gamma correction flag is 0) or 0..255 scaled file encoded values
\r
2213 * (if the function must gamma correct them).
\r
2215 for (i=val=0; i<cmap_entries; ++i, val += step)
\r
2217 /* 'i' is a file value. While this will result in duplicated
\r
2218 * entries for 8-bit non-sRGB encoded files it is necessary to
\r
2219 * have non-gamma corrected values to do tRNS handling.
\r
2222 png_create_colormap_entry(display, i, val, val, val, 255,
\r
2223 P_FILE/*8-bit with file gamma*/);
\r
2225 /* Else this entry is transparent. The colors don't matter if
\r
2226 * there is an alpha channel (back_alpha == 0), but it does no
\r
2227 * harm to pass them in; the values are not set above so this
\r
2228 * passes in white.
\r
2230 * NOTE: this preserves the full precision of the application
\r
2231 * supplied background color when it is used.
\r
2234 png_create_colormap_entry(display, i, back_r, back_g, back_b,
\r
2235 back_alpha, output_encoding);
\r
2238 /* We need libpng to preserve the original encoding. */
\r
2239 data_encoding = P_FILE;
\r
2241 /* The rows from libpng, while technically gray values, are now also
\r
2242 * color-map indices; however, they may need to be expanded to 1
\r
2243 * byte per pixel. This is what png_set_packing does (i.e., it
\r
2244 * unpacks the bit values into bytes.)
\r
2246 if (png_ptr->bit_depth < 8)
\r
2247 png_set_packing(png_ptr);
\r
2250 else /* bit depth is 16 */
\r
2252 /* The 16-bit input values can be converted directly to 8-bit gamma
\r
2253 * encoded values; however, if a tRNS chunk is present 257 color-map
\r
2254 * entries are required. This means that the extra entry requires
\r
2255 * special processing; add an alpha channel, sacrifice gray level
\r
2256 * 254 and convert transparent (alpha==0) entries to that.
\r
2258 * Use libpng to chop the data to 8 bits. Convert it to sRGB at the
\r
2259 * same time to minimize quality loss. If a tRNS chunk is present
\r
2260 * this means libpng must handle it too; otherwise it is impossible
\r
2261 * to do the exact match on the 16-bit value.
\r
2263 * If the output has no alpha channel *and* the background color is
\r
2264 * gray then it is possible to let libpng handle the substitution by
\r
2265 * ensuring that the corresponding gray level matches the background
\r
2268 data_encoding = P_sRGB;
\r
2270 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
\r
2271 png_error(png_ptr, "gray[16] color-map: too few entries");
\r
2273 cmap_entries = (unsigned int)make_gray_colormap(display);
\r
2275 if (png_ptr->num_trans > 0)
\r
2277 unsigned int back_alpha;
\r
2279 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
2284 if (back_r == back_g && back_g == back_b)
\r
2286 /* Background is gray; no special processing will be
\r
2290 png_uint_32 gray = back_g;
\r
2292 if (output_encoding == P_LINEAR)
\r
2294 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
\r
2296 /* And make sure the corresponding palette entry
\r
2299 png_create_colormap_entry(display, gray, back_g, back_g,
\r
2300 back_g, 65535, P_LINEAR);
\r
2303 /* The background passed to libpng, however, must be the
\r
2306 c.index = 0; /*unused*/
\r
2307 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
\r
2309 /* NOTE: does this work without expanding tRNS to alpha?
\r
2310 * It should be the color->gray case below apparently
\r
2313 png_set_background_fixed(png_ptr, &c,
\r
2314 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
\r
2315 0/*gamma: not used*/);
\r
2317 output_processing = PNG_CMAP_NONE;
\r
2320 #ifdef __COVERITY__
\r
2321 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
\r
2326 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
\r
2330 /* output_processing means that the libpng-processed row will be
\r
2331 * 8-bit GA and it has to be processing to single byte color-map
\r
2332 * values. Entry 254 is replaced by either a completely
\r
2333 * transparent entry or by the background color at full
\r
2334 * precision (and the background color is not a simple gray
\r
2335 * level in this case.)
\r
2338 output_processing = PNG_CMAP_TRANS;
\r
2339 background_index = 254;
\r
2341 /* And set (overwrite) color-map entry 254 to the actual
\r
2342 * background color at full precision.
\r
2344 png_create_colormap_entry(display, 254, back_r, back_g, back_b,
\r
2345 back_alpha, output_encoding);
\r
2349 output_processing = PNG_CMAP_NONE;
\r
2353 case PNG_COLOR_TYPE_GRAY_ALPHA:
\r
2354 /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
\r
2355 * of 65536 combinations. If, however, the alpha channel is to be
\r
2356 * removed there are only 256 possibilities if the background is gray.
\r
2357 * (Otherwise there is a subset of the 65536 possibilities defined by
\r
2358 * the triangle between black, white and the background color.)
\r
2360 * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
\r
2361 * worry about tRNS matching - tRNS is ignored if there is an alpha
\r
2364 data_encoding = P_sRGB;
\r
2366 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
2368 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
\r
2369 png_error(png_ptr, "gray+alpha color-map: too few entries");
\r
2371 cmap_entries = (unsigned int)make_ga_colormap(display);
\r
2373 background_index = PNG_CMAP_GA_BACKGROUND;
\r
2374 output_processing = PNG_CMAP_GA;
\r
2377 else /* alpha is removed */
\r
2379 /* Alpha must be removed as the PNG data is processed when the
\r
2380 * background is a color because the G and A channels are
\r
2381 * independent and the vector addition (non-parallel vectors) is a
\r
2384 * This can be reduced to the same algorithm as above by making a
\r
2385 * colormap containing gray levels (for the opaque grays), a
\r
2386 * background entry (for a transparent pixel) and a set of four six
\r
2387 * level color values, one set for each intermediate alpha value.
\r
2388 * See the comments in make_ga_colormap for how this works in the
\r
2389 * per-pixel processing.
\r
2391 * If the background is gray, however, we only need a 256 entry gray
\r
2392 * level color map. It is sufficient to make the entry generated
\r
2393 * for the background color be exactly the color specified.
\r
2395 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
\r
2396 (back_r == back_g && back_g == back_b))
\r
2398 /* Background is gray; no special processing will be required. */
\r
2400 png_uint_32 gray = back_g;
\r
2402 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
\r
2403 png_error(png_ptr, "gray-alpha color-map: too few entries");
\r
2405 cmap_entries = (unsigned int)make_gray_colormap(display);
\r
2407 if (output_encoding == P_LINEAR)
\r
2409 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
\r
2411 /* And make sure the corresponding palette entry matches. */
\r
2412 png_create_colormap_entry(display, gray, back_g, back_g,
\r
2413 back_g, 65535, P_LINEAR);
\r
2416 /* The background passed to libpng, however, must be the sRGB
\r
2419 c.index = 0; /*unused*/
\r
2420 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
\r
2422 png_set_background_fixed(png_ptr, &c,
\r
2423 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
\r
2424 0/*gamma: not used*/);
\r
2426 output_processing = PNG_CMAP_NONE;
\r
2433 /* This is the same as png_make_ga_colormap, above, except that
\r
2434 * the entries are all opaque.
\r
2436 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
\r
2437 png_error(png_ptr, "ga-alpha color-map: too few entries");
\r
2442 png_uint_32 gray = (i * 256 + 115) / 231;
\r
2443 png_create_colormap_entry(display, i++, gray, gray, gray,
\r
2447 /* NOTE: this preserves the full precision of the application
\r
2448 * background color.
\r
2450 background_index = i;
\r
2451 png_create_colormap_entry(display, i++, back_r, back_g, back_b,
\r
2452 #ifdef __COVERITY__
\r
2453 /* Coverity claims that output_encoding
\r
2454 * cannot be 2 (P_LINEAR) here.
\r
2457 output_encoding == P_LINEAR ? 65535U : 255U,
\r
2461 /* For non-opaque input composite on the sRGB background - this
\r
2462 * requires inverting the encoding for each component. The input
\r
2463 * is still converted to the sRGB encoding because this is a
\r
2464 * reasonable approximate to the logarithmic curve of human
\r
2465 * visual sensitivity, at least over the narrow range which PNG
\r
2466 * represents. Consequently 'G' is always sRGB encoded, while
\r
2467 * 'A' is linear. We need the linear background colors.
\r
2469 if (output_encoding == P_sRGB) /* else already linear */
\r
2471 /* This may produce a value not exactly matching the
\r
2472 * background, but that's ok because these numbers are only
\r
2473 * used when alpha != 0
\r
2475 back_r = png_sRGB_table[back_r];
\r
2476 back_g = png_sRGB_table[back_g];
\r
2477 back_b = png_sRGB_table[back_b];
\r
2480 for (a=1; a<5; ++a)
\r
2484 /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
\r
2485 * by an 8-bit alpha value (0..255).
\r
2487 png_uint_32 alpha = 51 * a;
\r
2488 png_uint_32 back_rx = (255-alpha) * back_r;
\r
2489 png_uint_32 back_gx = (255-alpha) * back_g;
\r
2490 png_uint_32 back_bx = (255-alpha) * back_b;
\r
2492 for (g=0; g<6; ++g)
\r
2494 png_uint_32 gray = png_sRGB_table[g*51] * alpha;
\r
2496 png_create_colormap_entry(display, i++,
\r
2497 PNG_sRGB_FROM_LINEAR(gray + back_rx),
\r
2498 PNG_sRGB_FROM_LINEAR(gray + back_gx),
\r
2499 PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
\r
2504 output_processing = PNG_CMAP_GA;
\r
2509 case PNG_COLOR_TYPE_RGB:
\r
2510 case PNG_COLOR_TYPE_RGB_ALPHA:
\r
2511 /* Exclude the case where the output is gray; we can always handle this
\r
2512 * with the cases above.
\r
2514 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
\r
2516 /* The color-map will be grayscale, so we may as well convert the
\r
2517 * input RGB values to a simple grayscale and use the grayscale
\r
2520 * NOTE: calling this apparently damages the recognition of the
\r
2521 * transparent color in background color handling; call
\r
2522 * png_set_tRNS_to_alpha before png_set_background_fixed.
\r
2524 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
\r
2526 data_encoding = P_sRGB;
\r
2528 /* The output will now be one or two 8-bit gray or gray+alpha
\r
2529 * channels. The more complex case arises when the input has alpha.
\r
2531 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
\r
2532 png_ptr->num_trans > 0) &&
\r
2533 (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
2535 /* Both input and output have an alpha channel, so no background
\r
2536 * processing is required; just map the GA bytes to the right
\r
2537 * color-map entry.
\r
2541 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
\r
2542 png_error(png_ptr, "rgb[ga] color-map: too few entries");
\r
2544 cmap_entries = (unsigned int)make_ga_colormap(display);
\r
2545 background_index = PNG_CMAP_GA_BACKGROUND;
\r
2546 output_processing = PNG_CMAP_GA;
\r
2551 /* Either the input or the output has no alpha channel, so there
\r
2552 * will be no non-opaque pixels in the color-map; it will just be
\r
2555 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
\r
2556 png_error(png_ptr, "rgb[gray] color-map: too few entries");
\r
2558 /* Ideally this code would use libpng to do the gamma correction,
\r
2559 * but if an input alpha channel is to be removed we will hit the
\r
2560 * libpng bug in gamma+compose+rgb-to-gray (the double gamma
\r
2561 * correction bug). Fix this by dropping the gamma correction in
\r
2562 * this case and doing it in the palette; this will result in
\r
2563 * duplicate palette entries, but that's better than the
\r
2564 * alternative of double gamma correction.
\r
2566 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
\r
2567 png_ptr->num_trans > 0) &&
\r
2568 png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
\r
2570 cmap_entries = (unsigned int)make_gray_file_colormap(display);
\r
2571 data_encoding = P_FILE;
\r
2575 cmap_entries = (unsigned int)make_gray_colormap(display);
\r
2577 /* But if the input has alpha or transparency it must be removed
\r
2579 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
\r
2580 png_ptr->num_trans > 0)
\r
2583 png_uint_32 gray = back_g;
\r
2585 /* We need to ensure that the application background exists in
\r
2586 * the colormap and that completely transparent pixels map to
\r
2587 * it. Achieve this simply by ensuring that the entry
\r
2588 * selected for the background really is the background color.
\r
2590 if (data_encoding == P_FILE) /* from the fixup above */
\r
2592 /* The app supplied a gray which is in output_encoding, we
\r
2593 * need to convert it to a value of the input (P_FILE)
\r
2594 * encoding then set this palette entry to the required
\r
2595 * output encoding.
\r
2597 if (output_encoding == P_sRGB)
\r
2598 gray = png_sRGB_table[gray]; /* now P_LINEAR */
\r
2600 gray = PNG_DIV257(png_gamma_16bit_correct(gray,
\r
2601 png_ptr->colorspace.gamma)); /* now P_FILE */
\r
2603 /* And make sure the corresponding palette entry contains
\r
2604 * exactly the required sRGB value.
\r
2606 png_create_colormap_entry(display, gray, back_g, back_g,
\r
2607 back_g, 0/*unused*/, output_encoding);
\r
2610 else if (output_encoding == P_LINEAR)
\r
2612 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
\r
2614 /* And make sure the corresponding palette entry matches.
\r
2616 png_create_colormap_entry(display, gray, back_g, back_g,
\r
2617 back_g, 0/*unused*/, P_LINEAR);
\r
2620 /* The background passed to libpng, however, must be the
\r
2621 * output (normally sRGB) value.
\r
2623 c.index = 0; /*unused*/
\r
2624 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
\r
2626 /* NOTE: the following is apparently a bug in libpng. Without
\r
2627 * it the transparent color recognition in
\r
2628 * png_set_background_fixed seems to go wrong.
\r
2631 png_set_background_fixed(png_ptr, &c,
\r
2632 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
\r
2633 0/*gamma: not used*/);
\r
2636 output_processing = PNG_CMAP_NONE;
\r
2640 else /* output is color */
\r
2642 /* We could use png_quantize here so long as there is no transparent
\r
2643 * color or alpha; png_quantize ignores alpha. Easier overall just
\r
2644 * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
\r
2645 * Consequently we always want libpng to produce sRGB data.
\r
2647 data_encoding = P_sRGB;
\r
2649 /* Is there any transparency or alpha? */
\r
2650 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
\r
2651 png_ptr->num_trans > 0)
\r
2653 /* Is there alpha in the output too? If so all four channels are
\r
2654 * processed into a special RGB cube with alpha support.
\r
2656 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
2660 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
\r
2661 png_error(png_ptr, "rgb+alpha color-map: too few entries");
\r
2663 cmap_entries = (unsigned int)make_rgb_colormap(display);
\r
2665 /* Add a transparent entry. */
\r
2666 png_create_colormap_entry(display, cmap_entries, 255, 255,
\r
2669 /* This is stored as the background index for the processing
\r
2672 background_index = cmap_entries++;
\r
2674 /* Add 27 r,g,b entries each with alpha 0.5. */
\r
2675 for (r=0; r<256; r = (r << 1) | 0x7f)
\r
2679 for (g=0; g<256; g = (g << 1) | 0x7f)
\r
2683 /* This generates components with the values 0, 127 and
\r
2686 for (b=0; b<256; b = (b << 1) | 0x7f)
\r
2687 png_create_colormap_entry(display, cmap_entries++,
\r
2688 r, g, b, 128, P_sRGB);
\r
2693 output_processing = PNG_CMAP_RGB_ALPHA;
\r
2698 /* Alpha/transparency must be removed. The background must
\r
2699 * exist in the color map (achieved by setting adding it after
\r
2700 * the 666 color-map). If the standard processing code will
\r
2701 * pick up this entry automatically that's all that is
\r
2702 * required; libpng can be called to do the background
\r
2705 unsigned int sample_size =
\r
2706 PNG_IMAGE_SAMPLE_SIZE(output_format);
\r
2707 png_uint_32 r, g, b; /* sRGB background */
\r
2709 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
\r
2710 png_error(png_ptr, "rgb-alpha color-map: too few entries");
\r
2712 cmap_entries = (unsigned int)make_rgb_colormap(display);
\r
2714 png_create_colormap_entry(display, cmap_entries, back_r,
\r
2715 back_g, back_b, 0/*unused*/, output_encoding);
\r
2717 if (output_encoding == P_LINEAR)
\r
2719 r = PNG_sRGB_FROM_LINEAR(back_r * 255);
\r
2720 g = PNG_sRGB_FROM_LINEAR(back_g * 255);
\r
2721 b = PNG_sRGB_FROM_LINEAR(back_b * 255);
\r
2731 /* Compare the newly-created color-map entry with the one the
\r
2732 * PNG_CMAP_RGB algorithm will use. If the two entries don't
\r
2733 * match, add the new one and set this as the background
\r
2736 if (memcmp((png_const_bytep)display->colormap +
\r
2737 sample_size * cmap_entries,
\r
2738 (png_const_bytep)display->colormap +
\r
2739 sample_size * PNG_RGB_INDEX(r,g,b),
\r
2740 sample_size) != 0)
\r
2742 /* The background color must be added. */
\r
2743 background_index = cmap_entries++;
\r
2745 /* Add 27 r,g,b entries each with created by composing with
\r
2746 * the background at alpha 0.5.
\r
2748 for (r=0; r<256; r = (r << 1) | 0x7f)
\r
2750 for (g=0; g<256; g = (g << 1) | 0x7f)
\r
2752 /* This generates components with the values 0, 127
\r
2755 for (b=0; b<256; b = (b << 1) | 0x7f)
\r
2756 png_create_colormap_entry(display, cmap_entries++,
\r
2757 png_colormap_compose(display, r, P_sRGB, 128,
\r
2758 back_r, output_encoding),
\r
2759 png_colormap_compose(display, g, P_sRGB, 128,
\r
2760 back_g, output_encoding),
\r
2761 png_colormap_compose(display, b, P_sRGB, 128,
\r
2762 back_b, output_encoding),
\r
2763 0/*unused*/, output_encoding);
\r
2768 output_processing = PNG_CMAP_RGB_ALPHA;
\r
2771 else /* background color is in the standard color-map */
\r
2775 c.index = 0; /*unused*/
\r
2776 c.red = (png_uint_16)back_r;
\r
2777 c.gray = c.green = (png_uint_16)back_g;
\r
2778 c.blue = (png_uint_16)back_b;
\r
2780 png_set_background_fixed(png_ptr, &c,
\r
2781 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
\r
2782 0/*gamma: not used*/);
\r
2784 output_processing = PNG_CMAP_RGB;
\r
2789 else /* no alpha or transparency in the input */
\r
2791 /* Alpha in the output is irrelevant, simply map the opaque input
\r
2792 * pixels to the 6x6x6 color-map.
\r
2794 if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
\r
2795 png_error(png_ptr, "rgb color-map: too few entries");
\r
2797 cmap_entries = (unsigned int)make_rgb_colormap(display);
\r
2798 output_processing = PNG_CMAP_RGB;
\r
2803 case PNG_COLOR_TYPE_PALETTE:
\r
2804 /* It's already got a color-map. It may be necessary to eliminate the
\r
2805 * tRNS entries though.
\r
2808 unsigned int num_trans = png_ptr->num_trans;
\r
2809 png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
\r
2810 png_const_colorp colormap = png_ptr->palette;
\r
2811 int do_background = trans != NULL &&
\r
2812 (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
\r
2815 /* Just in case: */
\r
2816 if (trans == NULL)
\r
2819 output_processing = PNG_CMAP_NONE;
\r
2820 data_encoding = P_FILE; /* Don't change from color-map indices */
\r
2821 cmap_entries = (unsigned int)png_ptr->num_palette;
\r
2822 if (cmap_entries > 256)
\r
2823 cmap_entries = 256;
\r
2825 if (cmap_entries > (unsigned int)image->colormap_entries)
\r
2826 png_error(png_ptr, "palette color-map: too few entries");
\r
2828 for (i=0; i < cmap_entries; ++i)
\r
2830 if (do_background != 0 && i < num_trans && trans[i] < 255)
\r
2832 if (trans[i] == 0)
\r
2833 png_create_colormap_entry(display, i, back_r, back_g,
\r
2834 back_b, 0, output_encoding);
\r
2838 /* Must compose the PNG file color in the color-map entry
\r
2839 * on the sRGB color in 'back'.
\r
2841 png_create_colormap_entry(display, i,
\r
2842 png_colormap_compose(display, colormap[i].red,
\r
2843 P_FILE, trans[i], back_r, output_encoding),
\r
2844 png_colormap_compose(display, colormap[i].green,
\r
2845 P_FILE, trans[i], back_g, output_encoding),
\r
2846 png_colormap_compose(display, colormap[i].blue,
\r
2847 P_FILE, trans[i], back_b, output_encoding),
\r
2848 output_encoding == P_LINEAR ? trans[i] * 257U :
\r
2855 png_create_colormap_entry(display, i, colormap[i].red,
\r
2856 colormap[i].green, colormap[i].blue,
\r
2857 i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
\r
2860 /* The PNG data may have indices packed in fewer than 8 bits, it
\r
2861 * must be expanded if so.
\r
2863 if (png_ptr->bit_depth < 8)
\r
2864 png_set_packing(png_ptr);
\r
2869 png_error(png_ptr, "invalid PNG color type");
\r
2873 /* Now deal with the output processing */
\r
2874 if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
\r
2875 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
\r
2876 png_set_tRNS_to_alpha(png_ptr);
\r
2878 switch (data_encoding)
\r
2881 /* Change to 8-bit sRGB */
\r
2882 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
\r
2886 if (png_ptr->bit_depth > 8)
\r
2887 png_set_scale_16(png_ptr);
\r
2892 png_error(png_ptr, "bad data option (internal error)");
\r
2896 if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
\r
2897 png_error(png_ptr, "color map overflow (BAD internal error)");
\r
2899 image->colormap_entries = cmap_entries;
\r
2901 /* Double check using the recorded background index */
\r
2902 switch (output_processing)
\r
2904 case PNG_CMAP_NONE:
\r
2905 if (background_index != PNG_CMAP_NONE_BACKGROUND)
\r
2906 goto bad_background;
\r
2910 if (background_index != PNG_CMAP_GA_BACKGROUND)
\r
2911 goto bad_background;
\r
2914 case PNG_CMAP_TRANS:
\r
2915 if (background_index >= cmap_entries ||
\r
2916 background_index != PNG_CMAP_TRANS_BACKGROUND)
\r
2917 goto bad_background;
\r
2920 case PNG_CMAP_RGB:
\r
2921 if (background_index != PNG_CMAP_RGB_BACKGROUND)
\r
2922 goto bad_background;
\r
2925 case PNG_CMAP_RGB_ALPHA:
\r
2926 if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
\r
2927 goto bad_background;
\r
2931 png_error(png_ptr, "bad processing option (internal error)");
\r
2934 png_error(png_ptr, "bad background index (internal error)");
\r
2937 display->colormap_processing = (int)output_processing;
\r
2942 /* The final part of the color-map read called from png_image_finish_read. */
\r
2944 png_image_read_and_map(png_voidp argument)
\r
2946 png_image_read_control *display = png_voidcast(png_image_read_control*,
\r
2948 png_imagep image = display->image;
\r
2949 png_structrp png_ptr = image->opaque->png_ptr;
\r
2952 /* Called when the libpng data must be transformed into the color-mapped
\r
2953 * form. There is a local row buffer in display->local and this routine must
\r
2954 * do the interlace handling.
\r
2956 switch (png_ptr->interlaced)
\r
2958 case PNG_INTERLACE_NONE:
\r
2962 case PNG_INTERLACE_ADAM7:
\r
2963 passes = PNG_INTERLACE_ADAM7_PASSES;
\r
2967 png_error(png_ptr, "unknown interlace type");
\r
2971 png_uint_32 height = image->height;
\r
2972 png_uint_32 width = image->width;
\r
2973 int proc = display->colormap_processing;
\r
2974 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
\r
2975 ptrdiff_t step_row = display->row_bytes;
\r
2978 for (pass = 0; pass < passes; ++pass)
\r
2980 unsigned int startx, stepx, stepy;
\r
2983 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
\r
2985 /* The row may be empty for a short image: */
\r
2986 if (PNG_PASS_COLS(width, pass) == 0)
\r
2989 startx = PNG_PASS_START_COL(pass);
\r
2990 stepx = PNG_PASS_COL_OFFSET(pass);
\r
2991 y = PNG_PASS_START_ROW(pass);
\r
2992 stepy = PNG_PASS_ROW_OFFSET(pass);
\r
2999 stepx = stepy = 1;
\r
3002 for (; y<height; y += stepy)
\r
3004 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
\r
3005 png_bytep outrow = first_row + y * step_row;
\r
3006 png_const_bytep end_row = outrow + width;
\r
3008 /* Read read the libpng data into the temporary buffer. */
\r
3009 png_read_row(png_ptr, inrow, NULL);
\r
3011 /* Now process the row according to the processing option, note
\r
3012 * that the caller verifies that the format of the libpng output
\r
3013 * data is as required.
\r
3019 for (; outrow < end_row; outrow += stepx)
\r
3021 /* The data is always in the PNG order */
\r
3022 unsigned int gray = *inrow++;
\r
3023 unsigned int alpha = *inrow++;
\r
3024 unsigned int entry;
\r
3026 /* NOTE: this code is copied as a comment in
\r
3027 * make_ga_colormap above. Please update the
\r
3028 * comment if you change this code!
\r
3030 if (alpha > 229) /* opaque */
\r
3032 entry = (231 * gray + 128) >> 8;
\r
3034 else if (alpha < 26) /* transparent */
\r
3038 else /* partially opaque */
\r
3040 entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
\r
3043 *outrow = (png_byte)entry;
\r
3047 case PNG_CMAP_TRANS:
\r
3048 for (; outrow < end_row; outrow += stepx)
\r
3050 png_byte gray = *inrow++;
\r
3051 png_byte alpha = *inrow++;
\r
3054 *outrow = PNG_CMAP_TRANS_BACKGROUND;
\r
3056 else if (gray != PNG_CMAP_TRANS_BACKGROUND)
\r
3060 *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
\r
3064 case PNG_CMAP_RGB:
\r
3065 for (; outrow < end_row; outrow += stepx)
\r
3067 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
\r
3072 case PNG_CMAP_RGB_ALPHA:
\r
3073 for (; outrow < end_row; outrow += stepx)
\r
3075 unsigned int alpha = inrow[3];
\r
3077 /* Because the alpha entries only hold alpha==0.5 values
\r
3078 * split the processing at alpha==0.25 (64) and 0.75
\r
3083 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
\r
3086 else if (alpha < 64)
\r
3087 *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
\r
3091 /* Likewise there are three entries for each of r, g
\r
3092 * and b. We could select the entry by popcount on
\r
3093 * the top two bits on those architectures that
\r
3094 * support it, this is what the code below does,
\r
3097 unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
\r
3099 /* Here are how the values map:
\r
3101 * 0x00 .. 0x3f -> 0
\r
3102 * 0x40 .. 0xbf -> 1
\r
3103 * 0xc0 .. 0xff -> 2
\r
3105 * So, as above with the explicit alpha checks, the
\r
3106 * breakpoints are at 64 and 196.
\r
3108 if (inrow[0] & 0x80) back_i += 9; /* red */
\r
3109 if (inrow[0] & 0x40) back_i += 9;
\r
3110 if (inrow[0] & 0x80) back_i += 3; /* green */
\r
3111 if (inrow[0] & 0x40) back_i += 3;
\r
3112 if (inrow[0] & 0x80) back_i += 1; /* blue */
\r
3113 if (inrow[0] & 0x40) back_i += 1;
\r
3115 *outrow = (png_byte)back_i;
\r
3133 png_image_read_colormapped(png_voidp argument)
\r
3135 png_image_read_control *display = png_voidcast(png_image_read_control*,
\r
3137 png_imagep image = display->image;
\r
3138 png_controlp control = image->opaque;
\r
3139 png_structrp png_ptr = control->png_ptr;
\r
3140 png_inforp info_ptr = control->info_ptr;
\r
3142 int passes = 0; /* As a flag */
\r
3144 PNG_SKIP_CHUNKS(png_ptr);
\r
3146 /* Update the 'info' structure and make sure the result is as required; first
\r
3147 * make sure to turn on the interlace handling if it will be required
\r
3148 * (because it can't be turned on *after* the call to png_read_update_info!)
\r
3150 if (display->colormap_processing == PNG_CMAP_NONE)
\r
3151 passes = png_set_interlace_handling(png_ptr);
\r
3153 png_read_update_info(png_ptr, info_ptr);
\r
3155 /* The expected output can be deduced from the colormap_processing option. */
\r
3156 switch (display->colormap_processing)
\r
3158 case PNG_CMAP_NONE:
\r
3159 /* Output must be one channel and one byte per pixel, the output
\r
3160 * encoding can be anything.
\r
3162 if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
\r
3163 info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
\r
3164 info_ptr->bit_depth == 8)
\r
3169 case PNG_CMAP_TRANS:
\r
3171 /* Output must be two channels and the 'G' one must be sRGB, the latter
\r
3172 * can be checked with an exact number because it should have been set
\r
3173 * to this number above!
\r
3175 if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
\r
3176 info_ptr->bit_depth == 8 &&
\r
3177 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
\r
3178 image->colormap_entries == 256)
\r
3183 case PNG_CMAP_RGB:
\r
3184 /* Output must be 8-bit sRGB encoded RGB */
\r
3185 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
\r
3186 info_ptr->bit_depth == 8 &&
\r
3187 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
\r
3188 image->colormap_entries == 216)
\r
3193 case PNG_CMAP_RGB_ALPHA:
\r
3194 /* Output must be 8-bit sRGB encoded RGBA */
\r
3195 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
\r
3196 info_ptr->bit_depth == 8 &&
\r
3197 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
\r
3198 image->colormap_entries == 244 /* 216 + 1 + 27 */)
\r
3205 png_error(png_ptr, "bad color-map processing (internal error)");
\r
3208 /* Now read the rows. Do this here if it is possible to read directly into
\r
3209 * the output buffer, otherwise allocate a local row buffer of the maximum
\r
3210 * size libpng requires and call the relevant processing routine safely.
\r
3213 png_voidp first_row = display->buffer;
\r
3214 ptrdiff_t row_bytes = display->row_stride;
\r
3216 /* The following expression is designed to work correctly whether it gives
\r
3217 * a signed or an unsigned result.
\r
3219 if (row_bytes < 0)
\r
3221 char *ptr = png_voidcast(char*, first_row);
\r
3222 ptr += (image->height-1) * (-row_bytes);
\r
3223 first_row = png_voidcast(png_voidp, ptr);
\r
3226 display->first_row = first_row;
\r
3227 display->row_bytes = row_bytes;
\r
3233 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
\r
3235 display->local_row = row;
\r
3236 result = png_safe_execute(image, png_image_read_and_map, display);
\r
3237 display->local_row = NULL;
\r
3238 png_free(png_ptr, row);
\r
3245 png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
\r
3247 while (--passes >= 0)
\r
3249 png_uint_32 y = image->height;
\r
3250 png_bytep row = png_voidcast(png_bytep, display->first_row);
\r
3252 for (; y > 0; --y)
\r
3254 png_read_row(png_ptr, row, NULL);
\r
3263 /* Just the row reading part of png_image_read. */
\r
3265 png_image_read_composite(png_voidp argument)
\r
3267 png_image_read_control *display = png_voidcast(png_image_read_control*,
\r
3269 png_imagep image = display->image;
\r
3270 png_structrp png_ptr = image->opaque->png_ptr;
\r
3273 switch (png_ptr->interlaced)
\r
3275 case PNG_INTERLACE_NONE:
\r
3279 case PNG_INTERLACE_ADAM7:
\r
3280 passes = PNG_INTERLACE_ADAM7_PASSES;
\r
3284 png_error(png_ptr, "unknown interlace type");
\r
3288 png_uint_32 height = image->height;
\r
3289 png_uint_32 width = image->width;
\r
3290 ptrdiff_t step_row = display->row_bytes;
\r
3291 unsigned int channels =
\r
3292 (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
\r
3295 for (pass = 0; pass < passes; ++pass)
\r
3297 unsigned int startx, stepx, stepy;
\r
3300 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
\r
3302 /* The row may be empty for a short image: */
\r
3303 if (PNG_PASS_COLS(width, pass) == 0)
\r
3306 startx = PNG_PASS_START_COL(pass) * channels;
\r
3307 stepx = PNG_PASS_COL_OFFSET(pass) * channels;
\r
3308 y = PNG_PASS_START_ROW(pass);
\r
3309 stepy = PNG_PASS_ROW_OFFSET(pass);
\r
3320 for (; y<height; y += stepy)
\r
3322 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
\r
3324 png_const_bytep end_row;
\r
3326 /* Read the row, which is packed: */
\r
3327 png_read_row(png_ptr, inrow, NULL);
\r
3329 outrow = png_voidcast(png_bytep, display->first_row);
\r
3330 outrow += y * step_row;
\r
3331 end_row = outrow + width * channels;
\r
3333 /* Now do the composition on each pixel in this row. */
\r
3335 for (; outrow < end_row; outrow += stepx)
\r
3337 png_byte alpha = inrow[channels];
\r
3339 if (alpha > 0) /* else no change to the output */
\r
3343 for (c=0; c<channels; ++c)
\r
3345 png_uint_32 component = inrow[c];
\r
3347 if (alpha < 255) /* else just use component */
\r
3349 /* This is PNG_OPTIMIZED_ALPHA, the component value
\r
3350 * is a linear 8-bit value. Combine this with the
\r
3351 * current outrow[c] value which is sRGB encoded.
\r
3352 * Arithmetic here is 16-bits to preserve the output
\r
3353 * values correctly.
\r
3355 component *= 257*255; /* =65535 */
\r
3356 component += (255-alpha)*png_sRGB_table[outrow[c]];
\r
3358 /* So 'component' is scaled by 255*65535 and is
\r
3359 * therefore appropriate for the sRGB to linear
\r
3360 * conversion table.
\r
3362 component = PNG_sRGB_FROM_LINEAR(component);
\r
3365 outrow[c] = (png_byte)component;
\r
3369 inrow += channels+1; /* components and alpha channel */
\r
3378 /* The do_local_background case; called when all the following transforms are to
\r
3385 * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
\r
3386 * PNG_COMPOSITE code performs gamma correction, so we get double gamma
\r
3387 * correction. The fix-up is to prevent the PNG_COMPOSITE operation from
\r
3388 * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
\r
3389 * row and handles the removal or pre-multiplication of the alpha channel.
\r
3392 png_image_read_background(png_voidp argument)
\r
3394 png_image_read_control *display = png_voidcast(png_image_read_control*,
\r
3396 png_imagep image = display->image;
\r
3397 png_structrp png_ptr = image->opaque->png_ptr;
\r
3398 png_inforp info_ptr = image->opaque->info_ptr;
\r
3399 png_uint_32 height = image->height;
\r
3400 png_uint_32 width = image->width;
\r
3403 /* Double check the convoluted logic below. We expect to get here with
\r
3404 * libpng doing rgb to gray and gamma correction but background processing
\r
3405 * left to the png_image_read_background function. The rows libpng produce
\r
3406 * might be 8 or 16-bit but should always have two channels; gray plus alpha.
\r
3408 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
\r
3409 png_error(png_ptr, "lost rgb to gray");
\r
3411 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
\r
3412 png_error(png_ptr, "unexpected compose");
\r
3414 if (png_get_channels(png_ptr, info_ptr) != 2)
\r
3415 png_error(png_ptr, "lost/gained channels");
\r
3417 /* Expect the 8-bit case to always remove the alpha channel */
\r
3418 if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
\r
3419 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
3420 png_error(png_ptr, "unexpected 8-bit transformation");
\r
3422 switch (png_ptr->interlaced)
\r
3424 case PNG_INTERLACE_NONE:
\r
3428 case PNG_INTERLACE_ADAM7:
\r
3429 passes = PNG_INTERLACE_ADAM7_PASSES;
\r
3433 png_error(png_ptr, "unknown interlace type");
\r
3436 /* Use direct access to info_ptr here because otherwise the simplified API
\r
3437 * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
\r
3438 * checking the value after libpng expansions, not the original value in the
\r
3441 switch (info_ptr->bit_depth)
\r
3444 /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
\r
3445 * to be removed by composing on a background: either the row if
\r
3446 * display->background is NULL or display->background->green if not.
\r
3447 * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
\r
3450 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
\r
3451 ptrdiff_t step_row = display->row_bytes;
\r
3453 for (pass = 0; pass < passes; ++pass)
\r
3455 png_bytep row = png_voidcast(png_bytep, display->first_row);
\r
3456 unsigned int startx, stepx, stepy;
\r
3459 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
\r
3461 /* The row may be empty for a short image: */
\r
3462 if (PNG_PASS_COLS(width, pass) == 0)
\r
3465 startx = PNG_PASS_START_COL(pass);
\r
3466 stepx = PNG_PASS_COL_OFFSET(pass);
\r
3467 y = PNG_PASS_START_ROW(pass);
\r
3468 stepy = PNG_PASS_ROW_OFFSET(pass);
\r
3475 stepx = stepy = 1;
\r
3478 if (display->background == NULL)
\r
3480 for (; y<height; y += stepy)
\r
3482 png_bytep inrow = png_voidcast(png_bytep,
\r
3483 display->local_row);
\r
3484 png_bytep outrow = first_row + y * step_row;
\r
3485 png_const_bytep end_row = outrow + width;
\r
3487 /* Read the row, which is packed: */
\r
3488 png_read_row(png_ptr, inrow, NULL);
\r
3490 /* Now do the composition on each pixel in this row. */
\r
3492 for (; outrow < end_row; outrow += stepx)
\r
3494 png_byte alpha = inrow[1];
\r
3496 if (alpha > 0) /* else no change to the output */
\r
3498 png_uint_32 component = inrow[0];
\r
3500 if (alpha < 255) /* else just use component */
\r
3502 /* Since PNG_OPTIMIZED_ALPHA was not set it is
\r
3503 * necessary to invert the sRGB transfer
\r
3504 * function and multiply the alpha out.
\r
3506 component = png_sRGB_table[component] * alpha;
\r
3507 component += png_sRGB_table[outrow[0]] *
\r
3509 component = PNG_sRGB_FROM_LINEAR(component);
\r
3512 outrow[0] = (png_byte)component;
\r
3515 inrow += 2; /* gray and alpha channel */
\r
3520 else /* constant background value */
\r
3522 png_byte background8 = display->background->green;
\r
3523 png_uint_16 background = png_sRGB_table[background8];
\r
3525 for (; y<height; y += stepy)
\r
3527 png_bytep inrow = png_voidcast(png_bytep,
\r
3528 display->local_row);
\r
3529 png_bytep outrow = first_row + y * step_row;
\r
3530 png_const_bytep end_row = outrow + width;
\r
3532 /* Read the row, which is packed: */
\r
3533 png_read_row(png_ptr, inrow, NULL);
\r
3535 /* Now do the composition on each pixel in this row. */
\r
3537 for (; outrow < end_row; outrow += stepx)
\r
3539 png_byte alpha = inrow[1];
\r
3541 if (alpha > 0) /* else use background */
\r
3543 png_uint_32 component = inrow[0];
\r
3545 if (alpha < 255) /* else just use component */
\r
3547 component = png_sRGB_table[component] * alpha;
\r
3548 component += background * (255-alpha);
\r
3549 component = PNG_sRGB_FROM_LINEAR(component);
\r
3552 outrow[0] = (png_byte)component;
\r
3556 outrow[0] = background8;
\r
3558 inrow += 2; /* gray and alpha channel */
\r
3561 row += display->row_bytes;
\r
3569 /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
\r
3570 * still be done and, maybe, the alpha channel removed. This code also
\r
3571 * handles the alpha-first option.
\r
3574 png_uint_16p first_row = png_voidcast(png_uint_16p,
\r
3575 display->first_row);
\r
3576 /* The division by two is safe because the caller passed in a
\r
3577 * stride which was multiplied by 2 (below) to get row_bytes.
\r
3579 ptrdiff_t step_row = display->row_bytes / 2;
\r
3580 unsigned int preserve_alpha = (image->format &
\r
3581 PNG_FORMAT_FLAG_ALPHA) != 0;
\r
3582 unsigned int outchannels = 1U+preserve_alpha;
\r
3583 int swap_alpha = 0;
\r
3585 # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
\r
3586 if (preserve_alpha != 0 &&
\r
3587 (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
\r
3591 for (pass = 0; pass < passes; ++pass)
\r
3593 unsigned int startx, stepx, stepy;
\r
3596 /* The 'x' start and step are adjusted to output components here.
\r
3598 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
\r
3600 /* The row may be empty for a short image: */
\r
3601 if (PNG_PASS_COLS(width, pass) == 0)
\r
3604 startx = PNG_PASS_START_COL(pass) * outchannels;
\r
3605 stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
\r
3606 y = PNG_PASS_START_ROW(pass);
\r
3607 stepy = PNG_PASS_ROW_OFFSET(pass);
\r
3614 stepx = outchannels;
\r
3618 for (; y<height; y += stepy)
\r
3620 png_const_uint_16p inrow;
\r
3621 png_uint_16p outrow = first_row + y*step_row;
\r
3622 png_uint_16p end_row = outrow + width * outchannels;
\r
3624 /* Read the row, which is packed: */
\r
3625 png_read_row(png_ptr, png_voidcast(png_bytep,
\r
3626 display->local_row), NULL);
\r
3627 inrow = png_voidcast(png_const_uint_16p, display->local_row);
\r
3629 /* Now do the pre-multiplication on each pixel in this row.
\r
3632 for (; outrow < end_row; outrow += stepx)
\r
3634 png_uint_32 component = inrow[0];
\r
3635 png_uint_16 alpha = inrow[1];
\r
3637 if (alpha > 0) /* else 0 */
\r
3639 if (alpha < 65535) /* else just use component */
\r
3641 component *= alpha;
\r
3642 component += 32767;
\r
3643 component /= 65535;
\r
3650 outrow[swap_alpha] = (png_uint_16)component;
\r
3651 if (preserve_alpha != 0)
\r
3652 outrow[1 ^ swap_alpha] = alpha;
\r
3654 inrow += 2; /* components and alpha channel */
\r
3663 png_error(png_ptr, "unexpected bit depth");
\r
3670 /* The guts of png_image_finish_read as a png_safe_execute callback. */
\r
3672 png_image_read_direct(png_voidp argument)
\r
3674 png_image_read_control *display = png_voidcast(png_image_read_control*,
\r
3676 png_imagep image = display->image;
\r
3677 png_structrp png_ptr = image->opaque->png_ptr;
\r
3678 png_inforp info_ptr = image->opaque->info_ptr;
\r
3680 png_uint_32 format = image->format;
\r
3681 int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
\r
3682 int do_local_compose = 0;
\r
3683 int do_local_background = 0; /* to avoid double gamma correction bug */
\r
3686 /* Add transforms to ensure the correct output format is produced then check
\r
3687 * that the required implementation support is there. Always expand; always
\r
3688 * need 8 bits minimum, no palette and expanded tRNS.
\r
3690 png_set_expand(png_ptr);
\r
3692 /* Now check the format to see if it was modified. */
\r
3694 png_uint_32 base_format = png_image_format(png_ptr) &
\r
3695 ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
\r
3696 png_uint_32 change = format ^ base_format;
\r
3697 png_fixed_point output_gamma;
\r
3698 int mode; /* alpha mode */
\r
3700 /* Do this first so that we have a record if rgb to gray is happening. */
\r
3701 if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
\r
3703 /* gray<->color transformation required. */
\r
3704 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
\r
3705 png_set_gray_to_rgb(png_ptr);
\r
3709 /* libpng can't do both rgb to gray and
\r
3710 * background/pre-multiplication if there is also significant gamma
\r
3711 * correction, because both operations require linear colors and
\r
3712 * the code only supports one transform doing the gamma correction.
\r
3713 * Handle this by doing the pre-multiplication or background
\r
3714 * operation in this code, if necessary.
\r
3716 * TODO: fix this by rewriting pngrtran.c (!)
\r
3718 * For the moment (given that fixing this in pngrtran.c is an
\r
3719 * enormous change) 'do_local_background' is used to indicate that
\r
3720 * the problem exists.
\r
3722 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
3723 do_local_background = 1/*maybe*/;
\r
3725 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
\r
3726 PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
\r
3729 change &= ~PNG_FORMAT_FLAG_COLOR;
\r
3732 /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
\r
3735 png_fixed_point input_gamma_default;
\r
3737 if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
\r
3738 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
\r
3739 input_gamma_default = PNG_GAMMA_LINEAR;
\r
3741 input_gamma_default = PNG_DEFAULT_sRGB;
\r
3743 /* Call png_set_alpha_mode to set the default for the input gamma; the
\r
3744 * output gamma is set by a second call below.
\r
3746 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
\r
3751 /* If there *is* an alpha channel in the input it must be multiplied
\r
3752 * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
\r
3754 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
3755 mode = PNG_ALPHA_STANDARD; /* associated alpha */
\r
3758 mode = PNG_ALPHA_PNG;
\r
3760 output_gamma = PNG_GAMMA_LINEAR;
\r
3765 mode = PNG_ALPHA_PNG;
\r
3766 output_gamma = PNG_DEFAULT_sRGB;
\r
3769 if ((change & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0)
\r
3771 mode = PNG_ALPHA_OPTIMIZED;
\r
3772 change &= ~PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
\r
3775 /* If 'do_local_background' is set check for the presence of gamma
\r
3776 * correction; this is part of the work-round for the libpng bug
\r
3777 * described above.
\r
3779 * TODO: fix libpng and remove this.
\r
3781 if (do_local_background != 0)
\r
3783 png_fixed_point gtest;
\r
3785 /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
\r
3786 * gamma correction, the screen gamma hasn't been set on png_struct
\r
3787 * yet; it's set below. png_struct::gamma, however, is set to the
\r
3790 if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma,
\r
3791 PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
\r
3792 do_local_background = 0;
\r
3794 else if (mode == PNG_ALPHA_STANDARD)
\r
3796 do_local_background = 2/*required*/;
\r
3797 mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
\r
3800 /* else leave as 1 for the checks below */
\r
3803 /* If the bit-depth changes then handle that here. */
\r
3804 if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
\r
3806 if (linear != 0 /*16-bit output*/)
\r
3807 png_set_expand_16(png_ptr);
\r
3809 else /* 8-bit output */
\r
3810 png_set_scale_16(png_ptr);
\r
3812 change &= ~PNG_FORMAT_FLAG_LINEAR;
\r
3815 /* Now the background/alpha channel changes. */
\r
3816 if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
3818 /* Removing an alpha channel requires composition for the 8-bit
\r
3819 * formats; for the 16-bit it is already done, above, by the
\r
3820 * pre-multiplication and the channel just needs to be stripped.
\r
3822 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
3824 /* If RGB->gray is happening the alpha channel must be left and the
\r
3825 * operation completed locally.
\r
3827 * TODO: fix libpng and remove this.
\r
3829 if (do_local_background != 0)
\r
3830 do_local_background = 2/*required*/;
\r
3832 /* 16-bit output: just remove the channel */
\r
3833 else if (linear != 0) /* compose on black (well, pre-multiply) */
\r
3834 png_set_strip_alpha(png_ptr);
\r
3836 /* 8-bit output: do an appropriate compose */
\r
3837 else if (display->background != NULL)
\r
3841 c.index = 0; /*unused*/
\r
3842 c.red = display->background->red;
\r
3843 c.green = display->background->green;
\r
3844 c.blue = display->background->blue;
\r
3845 c.gray = display->background->green;
\r
3847 /* This is always an 8-bit sRGB value, using the 'green' channel
\r
3848 * for gray is much better than calculating the luminance here;
\r
3849 * we can get off-by-one errors in that calculation relative to
\r
3850 * the app expectations and that will show up in transparent
\r
3853 png_set_background_fixed(png_ptr, &c,
\r
3854 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
\r
3855 0/*gamma: not used*/);
\r
3858 else /* compose on row: implemented below. */
\r
3860 do_local_compose = 1;
\r
3861 /* This leaves the alpha channel in the output, so it has to be
\r
3862 * removed by the code below. Set the encoding to the 'OPTIMIZE'
\r
3863 * one so the code only has to hack on the pixels that require
\r
3866 mode = PNG_ALPHA_OPTIMIZED;
\r
3870 else /* output needs an alpha channel */
\r
3872 /* This is tricky because it happens before the swap operation has
\r
3873 * been accomplished; however, the swap does *not* swap the added
\r
3874 * alpha channel (weird API), so it must be added in the correct
\r
3877 png_uint_32 filler; /* opaque filler */
\r
3886 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
\r
3887 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
\r
3889 where = PNG_FILLER_BEFORE;
\r
3890 change &= ~PNG_FORMAT_FLAG_AFIRST;
\r
3895 where = PNG_FILLER_AFTER;
\r
3897 png_set_add_alpha(png_ptr, filler, where);
\r
3900 /* This stops the (irrelevant) call to swap_alpha below. */
\r
3901 change &= ~PNG_FORMAT_FLAG_ALPHA;
\r
3904 /* Now set the alpha mode correctly; this is always done, even if there is
\r
3905 * no alpha channel in either the input or the output because it correctly
\r
3906 * sets the output gamma.
\r
3908 png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
\r
3910 # ifdef PNG_FORMAT_BGR_SUPPORTED
\r
3911 if ((change & PNG_FORMAT_FLAG_BGR) != 0)
\r
3913 /* Check only the output format; PNG is never BGR; don't do this if
\r
3914 * the output is gray, but fix up the 'format' value in that case.
\r
3916 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
\r
3917 png_set_bgr(png_ptr);
\r
3920 format &= ~PNG_FORMAT_FLAG_BGR;
\r
3922 change &= ~PNG_FORMAT_FLAG_BGR;
\r
3926 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
\r
3927 if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
\r
3929 /* Only relevant if there is an alpha channel - it's particularly
\r
3930 * important to handle this correctly because do_local_compose may
\r
3931 * be set above and then libpng will keep the alpha channel for this
\r
3934 if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
3936 /* Disable this if doing a local background,
\r
3937 * TODO: remove this when local background is no longer required.
\r
3939 if (do_local_background != 2)
\r
3940 png_set_swap_alpha(png_ptr);
\r
3944 format &= ~PNG_FORMAT_FLAG_AFIRST;
\r
3946 change &= ~PNG_FORMAT_FLAG_AFIRST;
\r
3950 /* If the *output* is 16-bit then we need to check for a byte-swap on this
\r
3955 png_uint_16 le = 0x0001;
\r
3957 if ((*(png_const_bytep) & le) != 0)
\r
3958 png_set_swap(png_ptr);
\r
3961 /* If change is not now 0 some transformation is missing - error out. */
\r
3963 png_error(png_ptr, "png_read_image: unsupported transformation");
\r
3966 PNG_SKIP_CHUNKS(png_ptr);
\r
3968 /* Update the 'info' structure and make sure the result is as required; first
\r
3969 * make sure to turn on the interlace handling if it will be required
\r
3970 * (because it can't be turned on *after* the call to png_read_update_info!)
\r
3972 * TODO: remove the do_local_background fixup below.
\r
3974 if (do_local_compose == 0 && do_local_background != 2)
\r
3975 passes = png_set_interlace_handling(png_ptr);
\r
3977 png_read_update_info(png_ptr, info_ptr);
\r
3980 png_uint_32 info_format = 0;
\r
3982 if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
\r
3983 info_format |= PNG_FORMAT_FLAG_COLOR;
\r
3985 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
\r
3987 /* do_local_compose removes this channel below. */
\r
3988 if (do_local_compose == 0)
\r
3990 /* do_local_background does the same if required. */
\r
3991 if (do_local_background != 2 ||
\r
3992 (format & PNG_FORMAT_FLAG_ALPHA) != 0)
\r
3993 info_format |= PNG_FORMAT_FLAG_ALPHA;
\r
3997 else if (do_local_compose != 0) /* internal error */
\r
3998 png_error(png_ptr, "png_image_read: alpha channel lost");
\r
4000 if ((format & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) {
\r
4001 info_format |= PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
\r
4004 if (info_ptr->bit_depth == 16)
\r
4005 info_format |= PNG_FORMAT_FLAG_LINEAR;
\r
4007 #ifdef PNG_FORMAT_BGR_SUPPORTED
\r
4008 if ((png_ptr->transformations & PNG_BGR) != 0)
\r
4009 info_format |= PNG_FORMAT_FLAG_BGR;
\r
4012 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
\r
4013 if (do_local_background == 2)
\r
4015 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
\r
4016 info_format |= PNG_FORMAT_FLAG_AFIRST;
\r
4019 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
\r
4020 ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
\r
4021 (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
\r
4023 if (do_local_background == 2)
\r
4024 png_error(png_ptr, "unexpected alpha swap transformation");
\r
4026 info_format |= PNG_FORMAT_FLAG_AFIRST;
\r
4030 /* This is actually an internal error. */
\r
4031 if (info_format != format)
\r
4032 png_error(png_ptr, "png_read_image: invalid transformations");
\r
4035 /* Now read the rows. If do_local_compose is set then it is necessary to use
\r
4036 * a local row buffer. The output will be GA, RGBA or BGRA and must be
\r
4037 * converted to G, RGB or BGR as appropriate. The 'local_row' member of the
\r
4038 * display acts as a flag.
\r
4041 png_voidp first_row = display->buffer;
\r
4042 ptrdiff_t row_bytes = display->row_stride;
\r
4047 /* The following expression is designed to work correctly whether it gives
\r
4048 * a signed or an unsigned result.
\r
4050 if (row_bytes < 0)
\r
4052 char *ptr = png_voidcast(char*, first_row);
\r
4053 ptr += (image->height-1) * (-row_bytes);
\r
4054 first_row = png_voidcast(png_voidp, ptr);
\r
4057 display->first_row = first_row;
\r
4058 display->row_bytes = row_bytes;
\r
4061 if (do_local_compose != 0)
\r
4064 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
\r
4066 display->local_row = row;
\r
4067 result = png_safe_execute(image, png_image_read_composite, display);
\r
4068 display->local_row = NULL;
\r
4069 png_free(png_ptr, row);
\r
4074 else if (do_local_background == 2)
\r
4077 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
\r
4079 display->local_row = row;
\r
4080 result = png_safe_execute(image, png_image_read_background, display);
\r
4081 display->local_row = NULL;
\r
4082 png_free(png_ptr, row);
\r
4089 png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
\r
4091 while (--passes >= 0)
\r
4093 png_uint_32 y = image->height;
\r
4094 png_bytep row = png_voidcast(png_bytep, display->first_row);
\r
4096 for (; y > 0; --y)
\r
4098 png_read_row(png_ptr, row, NULL);
\r
4108 png_image_finish_read(png_imagep image, png_const_colorp background,
\r
4109 void *buffer, png_int_32 row_stride, void *colormap)
\r
4111 if (image != NULL && image->version == PNG_IMAGE_VERSION)
\r
4113 /* Check for row_stride overflow. This check is not performed on the
\r
4114 * original PNG format because it may not occur in the output PNG format
\r
4115 * and libpng deals with the issues of reading the original.
\r
4117 unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
\r
4119 /* The following checks just the 'row_stride' calculation to ensure it
\r
4120 * fits in a signed 32-bit value. Because channels/components can be
\r
4121 * either 1 or 2 bytes in size the length of a row can still overflow 32
\r
4122 * bits; this is just to verify that the 'row_stride' argument can be
\r
4125 if (image->width <= 0x7fffffffU/channels) /* no overflow */
\r
4127 png_uint_32 check;
\r
4128 png_uint_32 png_row_stride = image->width * channels;
\r
4130 if (row_stride == 0)
\r
4131 row_stride = (png_int_32)/*SAFE*/png_row_stride;
\r
4133 if (row_stride < 0)
\r
4134 check = (png_uint_32)(-row_stride);
\r
4137 check = (png_uint_32)row_stride;
\r
4139 /* This verifies 'check', the absolute value of the actual stride
\r
4140 * passed in and detects overflow in the application calculation (i.e.
\r
4141 * if the app did actually pass in a non-zero 'row_stride'.
\r
4143 if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
\r
4145 /* Now check for overflow of the image buffer calculation; this
\r
4146 * limits the whole image size to 32 bits for API compatibility with
\r
4147 * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
\r
4149 * The PNG_IMAGE_BUFFER_SIZE macro is:
\r
4151 * (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
\r
4153 * And the component size is always 1 or 2, so make sure that the
\r
4154 * number of *bytes* that the application is saying are available
\r
4155 * does actually fit into a 32-bit number.
\r
4157 * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE
\r
4158 * will be changed to use png_alloc_size_t; bigger images can be
\r
4159 * accommodated on 64-bit systems.
\r
4161 if (image->height <=
\r
4162 0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
\r
4164 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
\r
4165 (image->colormap_entries > 0 && colormap != NULL))
\r
4168 png_image_read_control display;
\r
4170 memset(&display, 0, (sizeof display));
\r
4171 display.image = image;
\r
4172 display.buffer = buffer;
\r
4173 display.row_stride = row_stride;
\r
4174 display.colormap = colormap;
\r
4175 display.background = background;
\r
4176 display.local_row = NULL;
\r
4178 /* Choose the correct 'end' routine; for the color-map case
\r
4179 * all the setup has already been done.
\r
4181 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
\r
4183 png_safe_execute(image,
\r
4184 png_image_read_colormap, &display) &&
\r
4185 png_safe_execute(image,
\r
4186 png_image_read_colormapped, &display);
\r
4190 png_safe_execute(image,
\r
4191 png_image_read_direct, &display);
\r
4193 png_image_free(image);
\r
4198 return png_image_error(image,
\r
4199 "png_image_finish_read[color-map]: no color-map");
\r
4203 return png_image_error(image,
\r
4204 "png_image_finish_read: image too large");
\r
4208 return png_image_error(image,
\r
4209 "png_image_finish_read: invalid argument");
\r
4213 return png_image_error(image,
\r
4214 "png_image_finish_read: row_stride too large");
\r
4217 else if (image != NULL)
\r
4218 return png_image_error(image,
\r
4219 "png_image_finish_read: damaged PNG_IMAGE_VERSION");
\r
4224 #endif /* SIMPLIFIED_READ */
\r
projects / irrlicht.git / blob