+ tooWide := (w < len(fileRunes))
+
+ // if the entire tab-bar is longer than the screen is wide,
+ // then it should be truncated appropriately to keep the
+ // active tab visible on the UI.
+ if tooWide == true {
+ // first we have to work out where the selected tab is
+ // out of the total length of the tab bar. this is done
+ // by extracting the hit-areas from the indicies map
+ // that was constructed by `TabbarString()`
+ var keys []int
+ for offset := range indicies {
+ keys = append(keys, offset)
+ }
+ // sort them to be in ascending order so that values will
+ // correctly reflect the displayed ordering of the tabs
+ sort.Ints(keys)
+ // record the offset of each tab and the previous tab so
+ // we can find the position of the tab's hit-box.
+ previousTabOffset := 0
+ currentTabOffset := 0
+ for _, k := range keys {
+ tabIndex := indicies[k] - 1
+ if tabIndex == curTab {
+ currentTabOffset = k
+ break
+ }
+ // this is +2 because there are two padding spaces that aren't accounted
+ // for in the display. please note that this is for cosmetic purposes only.
+ previousTabOffset = k + 2
+ }
+ // get the width of the hitbox of the active tab, from there calculate the offsets
+ // to the left and right of it to approximately center it on the tab bar display.
+ centeringOffset := (w - (currentTabOffset - previousTabOffset))
+ leftBuffer := previousTabOffset - (centeringOffset / 2)
+ rightBuffer := currentTabOffset + (centeringOffset / 2)
+
+ // check to make sure we haven't overshot the bounds of the string,
+ // if we have, then take that remainder and put it on the left side
+ overshotRight := rightBuffer - len(fileRunes)
+ if overshotRight > 0 {
+ leftBuffer = leftBuffer + overshotRight
+ }
+
+ overshotLeft := leftBuffer - 0
+ if overshotLeft < 0 {
+ leftBuffer = 0
+ rightBuffer = leftBuffer + (w - 1)
+ } else {
+ rightBuffer = leftBuffer + (w - 2)
+ }
+
+ if rightBuffer > len(fileRunes)-1 {
+ rightBuffer = len(fileRunes) - 1
+ }
+
+ // construct a new buffer of text to put the
+ // newly formatted tab bar text into.
+ var displayText []rune
+
+ // if the left-side of the tab bar isn't at the start
+ // of the constructed tab bar text, then show that are
+ // more tabs to the left by displaying a "+"
+ if leftBuffer != 0 {
+ displayText = append(displayText, '+')
+ }
+ // copy the runes in from the original tab bar text string
+ // into the new display buffer
+ for x := leftBuffer; x < rightBuffer; x++ {
+ displayText = append(displayText, fileRunes[x])
+ }
+ // if there is more text to the right of the right-most
+ // column in the tab bar text, then indicate there are more
+ // tabs to the right by displaying a "+"
+ if rightBuffer < len(fileRunes)-1 {
+ displayText = append(displayText, '+')
+ }
+
+ // now store the offset from zero of the left-most text
+ // that is being displayed. This is to ensure that when
+ // clicking on the tab bar, the correct tab gets selected.
+ tabBarOffset = leftBuffer
+
+ // use the constructed buffer as the display buffer to print
+ // onscreen.
+ fileRunes = displayText
+ } else {
+ tabBarOffset = 0
+ }
+
+ // iterate over the width of the terminal display and for each column,
+ // write a character into the tab display area with the appropriate style.