Request: Text hAlign = JUSTIFY_ALIGN

[IagoBeuller]

Would be nice if add this alignment style.

I've made this proc for making this feature for me, it behaves like the Microsoft Word.

import
    pixie,
    unicode

const
    LF = Rune(10)
    NR = Rune(0)

proc justifyArrangement*(arrangement: Arrangement, maxWidth: float32) {.raises: [].} =
  proc right(rect: Rect): float32 = rect.x + rect.w
  
  let
    runes: ptr = arrangement.runes.addr
    positions: ptr = arrangement.positions.addr
    rects: ptr = arrangement.selectionRects.addr
    lastLineId: int = arrangement.lines.len-1
  
  var
    rune, lastRune: Rune
    lastWordRuneId: int
    spacesIdx: seq[int]
    incWidth, spaceWidth, lineWidth, xOffset: float32
  
  for lineId, (start, stop) in arrangement.lines:
    lastRune = runes[stop]

    # This line must not be justified, if it's the last or if the last rune is a breakline char.
    if lineId == lastLineId or lastRune == LF:
      continue

    echo runes[start..stop]
    # Get the spaces indexes of this line to increase their width, and get the line width.
    # Spaces in the end will be pushed away the maxWidth like the Microsoft Word.
    spacesIdx = @[]
    lastRune = NR
    for rId in start..stop:
      rune = runes[rId]
      if not rune.isWhiteSpace():
        if lastRune.isWhiteSpace():
          spacesIdx.add(rId-1)
        lastWordRuneId = rId
      lastRune = rune

    lineWidth = rects[lastWordRuneId].right

    echo "Line spaces: ", spacesIdx.len
    if spacesIdx.len > 0:
      # Get the amount of pixels/units to increase each space width in the middle of the line.
      incWidth = (maxWidth - lineWidth) / spacesIdx.len.float32

      if incWidth > 0:
        spaceWidth = rects[spacesIdx[0]].w + incWidth

        # Adjust the runes X position
        xOffset = 0
        for rId in spacesIdx[0]..stop:
          positions[rId].x += xOffset
          rects[rId].x += xOffset
          
          if rId in spacesIdx:
            rects[rId].w = spaceWidth
            xOffset += incWidth