The new alignment method works

Closes #1

README.md

@@ -5,4 +5,4 @@
 Typeset provides utilities for text layout, wrapping, and rendering.
 
 The state of a text layout is stored in a TypeSetter, and it can be drawn to any
-image.Image using a Drawer which "extends" TypeSetter.
+draw.Image using a Drawer which "extends" TypeSetter.

drawer.go

@@ -13,25 +13,31 @@ type Drawer struct { TypeSetter }
 // Draw draws the drawer's text onto the specified canvas at the given offset.
 func (drawer Drawer) Draw (
 	destination draw.Image,
-	color       color.Color,
+	col         color.Color,
 	offset      image.Point,
 ) (
 	updatedRegion image.Rectangle,
 ) {
-	source := image.NewUniform(color)
+	source := image.NewUniform(col)
 	
-	drawer.For (func (
+	drawer.ForRunes (func (
 		index    int,
 		char     rune,
 		position fixed.Point26_6,
 	) bool {
+		// leave empty space for space characters
+		if unicode.IsSpace(char) {
+			return true
+		}
+		
+		dot := fixed.P (
+			offset.X + position.X.Round(),
+			offset.Y + position.Y.Round())
 		destinationRectangle,
-		mask, maskPoint, _, ok := drawer.face.Glyph (
-			fixed.P (
-				offset.X + position.X.Round(),
-				offset.Y + position.Y.Round()),
-			char)
-		if !ok || unicode.IsSpace(char) || char == 0 {
+		mask, maskPoint, _, ok := drawer.face.Glyph(dot, char)
+		// tofu
+		if !ok {
+			drawer.drawTofu(char, destination, col, dot)
 			return true
 		}
 
@@ -50,3 +56,29 @@ func (drawer Drawer) Draw (
 	})
 	return
 }
+
+func (drawer Drawer) drawTofu (
+	char rune,
+	destination draw.Image,
+	col         color.Color,
+	position    fixed.Point26_6,
+) {
+	bounds, _ := tofuBounds(drawer.face)
+	rectBounds := image.Rect (
+		bounds.Min.X.Round(),
+		bounds.Min.Y.Round(),
+		bounds.Max.X.Round(),
+		bounds.Max.Y.Round()).Add(image.Pt(
+			position.X.Round(),
+			position.Y.Round()))
+	for x := rectBounds.Min.X; x < rectBounds.Max.X; x ++ {
+		destination.Set(x, rectBounds.Min.Y, col)
+	}
+	for y := rectBounds.Min.Y; y < rectBounds.Max.Y; y ++ {
+		destination.Set(rectBounds.Min.X, y, col)
+		destination.Set(rectBounds.Max.X - 1, y, col)
+	}
+	for x := rectBounds.Min.X; x < rectBounds.Max.X; x ++ {
+		destination.Set(x, rectBounds.Max.Y - 1, col)
+	}
+}

layout.go

@@ -58,13 +58,16 @@ func DoWord (text []rune, face font.Face) (word WordLayout, remaining []rune) {
 		
 		// consume and process the rune
 		remaining = remaining[1:]
-		_, advance, ok := face.GlyphBounds(char)
-		if !ok { continue }
-		word.Runes = append (word.Runes, RuneLayout {
+		advance, ok := face.GlyphAdvance(char)
+		if !ok {
+			advance = tofuAdvance(face)
+		}
+		runeLayout := RuneLayout {
 			X:     x,
 			Width: advance,
 			Rune:  char,
-		})
+		}
+		word.Runes = append(word.Runes, runeLayout)
 
 		// advance
 		if gettingSpace {
@@ -113,12 +116,10 @@ type LineLayout struct {
 func DoLine (text []rune, face font.Face, wrap bool, width fixed.Int26_6) (line LineLayout, remaining []rune) {
 	remaining    = text
 	x           := fixed.Int26_6(0)
-	lastWord    := WordLayout { }
 	isFirstWord := true
 	for {
 		// process one word
 		word, remainingFromWord := DoWord(remaining, face)
-		word.X = x
 		x += word.Width
 
 		// if we have gone over the preferred width, stop processing
@@ -132,7 +133,6 @@ func DoLine (text []rune, face font.Face, wrap bool, width fixed.Int26_6) (line
 
 		// if the word actually has contents, add it
 		if word.Runes != nil {
-			lastWord   = word
 			line.Words = append(line.Words, word)
 		}
 
@@ -148,9 +148,12 @@ func DoLine (text []rune, face font.Face, wrap bool, width fixed.Int26_6) (line
 	}
 
 	// set the width of the line's content.
-	line.ContentWidth = lastWord.X + lastWord.Width
 	line.Width = width
-	line.SpaceAfter = lastWord.SpaceAfter
+	if len(line.Words) > 0 {
+		lastWord := line.Words[len(line.Words) - 1]
+		line.ContentWidth = x - lastWord.SpaceAfter
+		line.SpaceAfter   = lastWord.SpaceAfter
+	}
 	return
 }
 
@@ -167,30 +170,45 @@ 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
+		}
 
-	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
+		for index := range line.Words {
+			line.Words[index].X += leftOffset
+		}
 	}
 }
 
-func (line *LineLayout) justify () {
-	if len(line.Words) < 2 {
-		line.Align(AlignStart)
+// assume line has content > 0
+func (line *LineLayout) contract (tabWidth fixed.Int26_6) {
+	x := fixed.Int26_6(0)
+	for index, word := range line.Words {
+		word.X = x
+		x += word.Width
+		x += word.SpaceAfter
+		line.Words[index] = word
+	}
+	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) <= 1 {
+		line.Align(AlignStart, tabWidth)
 		return
 	}
 
@@ -209,3 +227,19 @@ func (line *LineLayout) justify () {
 		x += spacePerWord + word.Width
 	}
 }
+
+func tofuAdvance (face font.Face) fixed.Int26_6 {
+	if advance, ok := face.GlyphAdvance('M'); ok {
+		return advance
+	} else {
+		return 16
+	}
+}
+
+func tofuBounds (face font.Face) (fixed.Rectangle26_6, fixed.Int26_6) {
+	if bounds, advance, ok := face.GlyphBounds('M'); ok {
+		return bounds, advance
+	} else {
+		return fixed.R(0, -16, 14, 0), 16
+	}
+}

setter.go

@@ -18,6 +18,7 @@ type TypeSetter struct {
 	face           font.Face
 	width, height  int
 	wrap           bool
+	tabWidth       fixed.Int26_6
 	
 	minWidth          fixed.Int26_6
 	layoutBounds      image.Rectangle
@@ -117,7 +118,7 @@ func (setter *TypeSetter) alignHorizontally () {
 		}
 
 		// align line
-		setter.lines[index].Align(align)
+		setter.lines[index].Align(align, setter.tabWidth)
 	}
 }
 
@@ -215,6 +216,14 @@ func (setter *TypeSetter) SetHeight (heignt int) {
 	setter.height = heignt
 }
 
+// SetTabWidth sets the distance between tab stops.
+func (setter *TypeSetter) SetTabWidth (tabWidth fixed.Int26_6) {
+	if setter.tabWidth == tabWidth { return }
+	setter.layoutClean = false
+	setter.alignClean  = false
+	setter.tabWidth = tabWidth
+}
+
 // Em returns the width of one emspace according to the typesetter's font, which
 // is the width of the capital letter 'M'.
 func (setter *TypeSetter) Em () (width fixed.Int26_6) {
@@ -259,8 +268,18 @@ type RuneIterator func (
 )
 
 // For calls the specified iterator for every rune in the typesetter. If the
-// iterator returns false, the loop will immediately stop.
+// iterator returns false, the loop will immediately stop. This method will
+// insert a fake null rune at the end.
 func (setter *TypeSetter) For (iterator RuneIterator) {
+	setter.forInternal(iterator, true)
+}
+
+// ForRunes is like For, but leaves out the fake null rune.
+func (setter *TypeSetter) ForRunes (iterator RuneIterator) {
+	setter.forInternal(iterator, false)
+}
+
+func (setter *TypeSetter) forInternal (iterator RuneIterator, fakeNull bool) {
 	setter.needAlignedLayout()
 
 	index := 0
@@ -271,7 +290,7 @@ func (setter *TypeSetter) For (iterator RuneIterator) {
 		for _, word := range line.Words {
 		for _, char := range word.Runes {
 			lastCharRightBound = word.X + char.X + char.Width
-			keepGoing := iterator (index, char.Rune, fixed.Point26_6 {
+			keepGoing := iterator(index, char.Rune, fixed.Point26_6 {
 				X: word.X + char.X,
 				Y: line.Y,
 			})
@@ -280,21 +299,24 @@ func (setter *TypeSetter) For (iterator RuneIterator) {
 		}}
 		
 		if line.BreakAfter {
-			keepGoing := iterator (index, '\n', fixed.Point26_6 {
+			keepGoing := iterator(index, '\n', fixed.Point26_6 {
 				X: lastCharRightBound,
 				Y: line.Y,
 			})
 			if !keepGoing { return }
 			index ++
+			lastCharRightBound = fixed.Int26_6(0)
 		}
 	}
 	
-	keepGoing := iterator (index, '\000', fixed.Point26_6 {
-		X: lastCharRightBound,
-		Y: lastLineY,
-	})
-	if !keepGoing { return }
-	index ++
+	if fakeNull {
+		keepGoing := iterator (index, '\000', fixed.Point26_6 {
+			X: lastCharRightBound,
+			Y: lastLineY,
+		})
+		if !keepGoing { return }
+		index ++
+	}
 }
 
 // AtPosition returns the index of the rune at the specified position.
@@ -373,10 +395,10 @@ func (setter *TypeSetter) MinimumSize () image.Point {
 	return image.Pt(width.Round(), height.Round())
 }
 
-// ReccomendedHeightFor returns the reccomended max height if the text were to
-// have its maximum width set to the given width. This does not alter the
+// RecommendedHeight returns the reccomended max height if the text were to have
+// its maximum width set to the given width. This does not alter the
 // typesetter's state.
-func (setter *TypeSetter) ReccomendedHeightFor (width int) (height int) {
+func (setter *TypeSetter) RecommendedHeight (width int) (height int) {
 	setter.needLayout()
 	
 	if setter.lines == nil { return }