Restructure alignment process

layout.go

@@ -114,6 +114,9 @@ type LineLayout struct {
 // is crossed. The word which would have crossed over the limit will not be
 // processed.
 func DoLine (text []rune, face font.Face, wrap bool, width fixed.Int26_6) (line LineLayout, remaining []rune) {
+	// TODO: remove all the positioning logic from here to avoid redundancy
+	// with LineLayout.Align, because that should get called anyways 100% of
+	// the time to account for tab stops
 	remaining    = text
 	x           := fixed.Int26_6(0)
 	lastWord    := WordLayout { }
@@ -170,30 +173,45 @@ func (line *LineLayout) Length () int {
 
 // Align aligns the text in the line according to the specified alignment
 // method.
-func (line *LineLayout) Align (align Align) {
+func (line *LineLayout) Align (align Align, tabWidth fixed.Int26_6) {
 	if len(line.Words) == 0 { return }
 	
 	if align == AlignEven {
-		line.justify()
-		return
+		line.justify(tabWidth)
+	} else {
+		line.contract(tabWidth)
+		
+		var leftOffset fixed.Int26_6
+		if align == AlignMiddle {
+			leftOffset = (line.Width - line.ContentWidth) / 2
+		} else if align == AlignEnd {
+			leftOffset = line.Width - line.ContentWidth
+		}
+
+		for index := range line.Words {
+			line.Words[index].X += leftOffset
+		}
 	}
 
-	leftOffset := -line.Words[0].X
-
-	if align == AlignMiddle {
-		leftOffset += (line.Width - line.ContentWidth) / 2
-	} else if align == AlignEnd {
-		leftOffset += line.Width - line.ContentWidth
-	}
-
-	for index := range line.Words {
-		line.Words[index].X += leftOffset
-	}
 }
 
-func (line *LineLayout) justify () {
+// assume line has content > 0
+func (line *LineLayout) contract (tabWidth fixed.Int26_6) {
+	x := fixed.Int26_6(0)
+	for _, word := range line.Words {
+		word.X = x
+		x += word.Width
+		x += word.SpaceAfter
+	}
+	lastWord := line.Words[len(line.Words) - 1]
+	line.ContentWidth = lastWord.X + lastWord.Width
+	line.SpaceAfter   = lastWord.SpaceAfter
+}
+
+// assume line has content > 0
+func (line *LineLayout) justify (tabWidth fixed.Int26_6) {
 	if len(line.Words) < 2 {
-		line.Align(AlignStart)
+		line.Align(AlignStart, tabWidth)
 		return
 	}
 

setter.go

@@ -118,7 +118,7 @@ func (setter *TypeSetter) alignHorizontally () {
 		}
 
 		// align line
-		setter.lines[index].Align(align)
+		setter.lines[index].Align(align, setter.tabWidth)
 	}
 }