Add footer encoding

diff --git a/init.lua b/init.lua
index 3b5389b88ddfb6b89f448680b7e1c277b06d82f6..919f41594489387e513a8b2462844467e92a8fb0 100644 (file)
--- a/init.lua
+++ b/init.lua
@@ -1,8 +1,10 @@
 tga_encoder = {}
 
+local LUA_ARGS_LIMIT = 1000
+
 local image = setmetatable({}, {
        __call = function(self, ...)
-               local t = setmetatable({}, {__index = image})
+               local t = setmetatable({}, {__index = self})
                t:constructor(...)
                return t
        end,
@@ -10,53 +12,60 @@ local image = setmetatable({}, {
 
 function image:constructor(pixels)
        self.bytes = {}
+       self.chunks = {self.bytes}
        self.pixels = pixels
-       self.width = #pixles[1]
+       self.width = #pixels[1]
        self.height = #pixels
 
        self:encode()
 end
 
-function image:write(size, value)
-       -- TGA uses little endian encoding
-       local l = #self.bytes
+function image:insert(byte)
+       table.insert(self.bytes, byte)
+       if #self.bytes == LUA_ARGS_LIMIT then
+               self.bytes = {}
+               table.insert(self.chunks, self.bytes)
+       end
+end
+
+function image:littleendian(size, value)
        for i = 1, size do
                local byte = value % 256
                value = value - byte
                value = value / 256
-               self.bytes[l + i] = byte
+               self:insert(byte)
        end
 end
 
 function image:encode_colormap_spec()
        -- first entry index
-       self:write(2, 0)
+       self:littleendian(2, 0)
        -- number of entries
-       self:write(2, 0)
+       self:littleendian(2, 0)
        -- number of bits per pixel
-       self:write(1, 0)
+       self:insert(0)
 end
 
 function image:encode_image_spec()
        -- X- and Y- origin
-       self:write(2, 0)
-       self:write(2, 0)
+       self:littleendian(2, 0)
+       self:littleendian(2, 0)
        -- width and height
-       self:write(2, width)
-       self:write(2, height)
+       self:littleendian(2, self.width)
+       self:littleendian(2, self.height)
        -- pixel depth
-       self:write(1, 24)
+       self:insert(24)
        -- image descriptor
-       self:write(1, 0)
+       self:insert(0)
 end
 
 function image:encode_header()
        -- id length
-       self:write(1, 0) -- no image id info
+       self:insert(0) -- no image id info
        -- color map type
-       self:write(1, 0) -- no color map
+       self:insert(0) -- no color map
        -- image type
-       self:write(1, 2) -- uncompressed true-color image
+       self:insert(2) -- uncompressed true-color image
        -- color map specification
        self:encode_colormap_spec()
        -- image specification
@@ -66,9 +75,9 @@ end
 function image:encode_data()
        for _, row in ipairs(self.pixels) do
                for _, pixel in ipairs(row) do
-                       self:write(1, row[3])
-                       self:write(1, row[2])
-                       self:write(1, row[1])
+                       self:insert(pixel[3])
+                       self:insert(pixel[2])
+                       self:insert(pixel[1])
                end
        end
 end
@@ -82,10 +91,18 @@ function image:encode()
        -- no extension area or file footer
 end
 
+function image:get_data()
+       local data = ""
+       for _, bytes in ipairs(self.chunks) do
+               data = data .. string.char(unpack(bytes))
+       end
+       return data .. string.char(0, 0, 0, 0) .. string.char(0, 0, 0, 0) .. "TRUEVISION-XFILE." .. string.char(0)
+end
+
 function image:save(filename)
-       self.data = self.data or string.char(unpack(self.bytes))
-       local f = assert(io.open(filename))
-       f:write(data)
+       self.data = self.data or self:get_data()
+       local f = assert(io.open(filename, "w"))
+       f:write(self.data)
        f:close()
 end