API changes to support future functionality

drawer.go

@@ -13,11 +13,13 @@ 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.RGBA,
+	color       color.Color,
 	offset      image.Point,
 ) (
 	updatedRegion image.Rectangle,
 ) {
+	source := image.NewUniform(color)
+	
 	drawer.For (func (
 		index    int,
 		char     rune,
@@ -39,7 +41,7 @@ func (drawer Drawer) Draw (
 		draw.DrawMask (
 			destination,
 			destinationRectangle,
-			image.NewUniform(color), image.Point { },
+			source, image.Point { },
 			mask, maskPoint,
 			draw.Over)
 

layout.go

@@ -108,10 +108,10 @@ type LineLayout struct {
 
 // DoLine consumes exactly one line from the given string, and produces a line
 // layout according to the given font. It returns the remaining text as well. If
-// maxWidth is greater than zero, this function will stop processing words once
-// the limit is crossed. The word which would have crossed over the limit will
-// not be processed.
-func DoLine (text []rune, face font.Face, maxWidth fixed.Int26_6) (line LineLayout, remaining []rune) {
+// wrap is set to true, this function will stop processing words once maxWidth
+// 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) {
 	remaining    = text
 	x           := fixed.Int26_6(0)
 	lastWord    := WordLayout { }
@@ -122,9 +122,9 @@ func DoLine (text []rune, face font.Face, maxWidth fixed.Int26_6) (line LineLayo
 		word.X = x
 		x += word.Width
 
-		// if we have gone over the maximum width, stop processing
-		// words (if maxWidth is even specified)
-		if !isFirstWord && maxWidth > 0 && x > maxWidth {
+		// if we have gone over the preferred width, stop processing
+		// words (if wrap is enabled)
+		if !isFirstWord && wrap && x > width {
 			break
 		}
 
@@ -150,18 +150,26 @@ func DoLine (text []rune, face font.Face, maxWidth fixed.Int26_6) (line LineLayo
 
 	// set the width of the line's content.
 	line.ContentWidth = lastWord.X + lastWord.Width
-
-	// set the line's width. this is subject to be overridden by the
-	// TypeSetter to match the longest line.
-	if maxWidth > 0 {
-		line.Width = maxWidth
+	if wrap {
+		line.Width = width
 	} else {
-		line.Width      = line.ContentWidth
-		line.SpaceAfter = lastWord.SpaceAfter
+		line.Width = line.ContentWidth
 	}
+	line.SpaceAfter = lastWord.SpaceAfter
 	return
 }
 
+// Length returns the amount of runes within the line, including the trailing
+// line break if it exists.
+func (line *LineLayout) Length () int {
+	lineSize := 0
+	for _, word := range line.Words {
+		lineSize += len(word.Runes)
+	}
+	if line.BreakAfter { lineSize ++ }
+	return lineSize
+}
+
 // Align aligns the text in the line according to the specified alignment
 // method.
 func (line *LineLayout) Align (align Align) {

setter.go

@@ -18,7 +18,9 @@ type TypeSetter struct {
 	face  font.Face
 	maxWidth  int
 	maxHeight int
-
+	wrap      bool
+	
+	minWidth          fixed.Int26_6
 	layoutBounds      image.Rectangle
 	layoutBoundsSpace image.Rectangle
 }
@@ -28,51 +30,52 @@ func (setter *TypeSetter) needLayout () {
 	setter.layoutClean = true
 	setter.alignClean  = false
 
-	// we need to have a font and some text to do anything
 	setter.lines = nil
 	setter.layoutBounds      = image.Rectangle { }
 	setter.layoutBoundsSpace = image.Rectangle { }
-	if len(setter.text) == 0 { return }
+	setter.minWidth          = 0
 	if setter.face  == nil { return }
 
 	horizontalExtent      := fixed.Int26_6(0)
 	horizontalExtentSpace := fixed.Int26_6(0)
-
-	metrics   := setter.face.Metrics()
-	remaining := setter.text
-	y         := fixed.Int26_6(0)
-	for len(remaining) > 0 {
-		// process one line
-		line, remainingFromLine := DoLine (
-			remaining, setter.face, fixed.I(setter.maxWidth))
-		remaining = remainingFromLine
-
-		// add the line
+	metrics               := setter.face.Metrics()
+	remaining             := setter.text
+	y                     := fixed.Int26_6(0)
+	
+	addLine := func (line LineLayout) {
 		line.Y = y
 		y += metrics.Height
-		if line.Width > horizontalExtent {
-			horizontalExtent = line.Width
+		if line.ContentWidth > horizontalExtent {
+			horizontalExtent = line.ContentWidth
 		}
-		lineWidthSpace := line.Width + line.SpaceAfter
+		lineWidthSpace := line.ContentWidth + line.SpaceAfter
 		if lineWidthSpace > horizontalExtentSpace {
 			horizontalExtentSpace = lineWidthSpace
 		}
 		setter.lines = append(setter.lines, line)
 	}
 
-	// set all line widths to horizontalExtent if we don't have a specified
-	// maximum width
-	if setter.maxWidth == 0 {
-		for index := range setter.lines {
-			setter.lines[index].Width = horizontalExtent
-		}
-		setter.layoutBounds.Max.X      = horizontalExtent.Round()
-		setter.layoutBoundsSpace.Max.X = horizontalExtentSpace.Round()
-	} else {
-		setter.layoutBounds.Max.X      = setter.maxWidth
-		setter.layoutBoundsSpace.Max.X = setter.maxWidth
+	// process every line until there are no more remaining runes
+	for len(remaining) > 0 {
+		line, remainingFromLine := DoLine (
+			remaining, setter.face, setter.wrap,
+			fixed.I(setter.maxWidth))
+		remaining = remainingFromLine
+		addLine(line)
 	}
 
+	// if there were no lines processed or the last line has a break after
+	// it, add a blank line at the end
+	needBlankLine :=
+		len(setter.lines) == 0 ||
+		setter.lines[len(setter.lines) - 1].BreakAfter
+	if needBlankLine { addLine(LineLayout { }) }
+
+	// calculate layout boundaries
+	setter.minWidth = horizontalExtentSpace
+	setter.layoutBounds.Max.X      = horizontalExtent.Round()
+	setter.layoutBoundsSpace.Max.X = horizontalExtentSpace.Round()
+
 	y -= metrics.Height
 	if setter.maxHeight == 0 {
 		setter.layoutBounds.Min.Y = -metrics.Ascent.Round()
@@ -96,18 +99,28 @@ func (setter *TypeSetter) needAlignedLayout () {
 
 	for index := range setter.lines {
 		align := setter.align
-		if index == len(setter.lines) - 1 && align == AlignJustify {
-			align = AlignLeft
+		if align == AlignJustify {
+			except :=
+				index == len(setter.lines) - 1 ||
+				setter.lines[index].BreakAfter
+			if except { align = AlignLeft }
 		}
 		setter.lines[index].Align(align)
 	}
 }
 
+// SetWrap sets whether or not the text wraps around and forms new lines.
+func (setter *TypeSetter) SetWrap (wrap bool) {
+	if setter.wrap == wrap { return }
+	setter.layoutClean = false
+	setter.wrap = wrap
+}
+
 // SetAlign sets the alignment method of the typesetter.
-func (setter *TypeSetter) SetAlign (align Align) {
-	if setter.align == align { return }
+func (setter *TypeSetter) SetAlign (horizontal, vertical Align) {
+	if setter.align == horizontal { return }
 	setter.alignClean = false
-	setter.align = align
+	setter.align = horizontal
 }
 
 // SetText sets the text content of the typesetter.
@@ -125,20 +138,19 @@ func (setter *TypeSetter) SetFace (face font.Face) {
 	setter.face = face
 }
 
-// SetMaxWidth sets the maximum width of the typesetter. If the maximum width
-// is greater than zero, the text will wrap to that width. If the maximum width
-// is zero, the text will not wrap and instead extend as far as it needs to.
-func (setter *TypeSetter) SetMaxWidth (width int) {
+// SetWidth sets the width of the typesetter. Text will still be able
+// to overflow outside of this width if wrapping is disabled.
+func (setter *TypeSetter) SetWidth (width int) {
 	if setter.maxWidth == width { return }
 	setter.layoutClean = false
 	setter.alignClean  = false
 	setter.maxWidth = width
 }
 
-// SetMaxHeight sets the maximum height of the typesetter. If the maximum height
-// is greater than zero, no lines will be laid out past that point. If the
-// maximum height is zero, the text's maximum height will not be constrained.
-func (setter *TypeSetter) SetMaxHeight (heignt int) {
+// SetHeight sets the height of the typesetter. If the height is greater than
+// zero, no lines will be laid out past it. If the height is zero, the text's
+// maximum height will not be constrained.
+func (setter *TypeSetter) SetHeight (heignt int) {
 	if setter.maxHeight == heignt { return }
 	setter.layoutClean = false
 	setter.alignClean  = false
@@ -159,14 +171,13 @@ func (setter *TypeSetter) LineHeight () fixed.Int26_6 {
 	return setter.face.Metrics().Height
 }
 
-// MaxWidth returns the maximum width of the typesetter as set by SetMaxWidth.
-func (setter *TypeSetter) MaxWidth () int {
+// Width returns the height of the typesetter as set by SetWidth.
+func (setter *TypeSetter) Width () int {
 	return setter.maxWidth
 }
 
-// MaxHeight returns the maximum height of the typesetter as set by
-// SetMaxHeight.
-func (setter *TypeSetter) MaxHeight () int {
+// Height returns the height of the typesetter as set by SetHeight.
+func (setter *TypeSetter) Height () int {
 	return setter.maxHeight
 }
 
@@ -238,27 +249,21 @@ func (setter *TypeSetter) AtPosition (position fixed.Point26_6) (index int) {
 	// find the first line who's bottom bound is greater than position.Y. if
 	// we haven't found it, then dont set the line variable (defaults to the
 	// last line)
-	metrics := setter.face.Metrics()
-	line := setter.lines[len(setter.lines) - 1]
-	lineSize := 0
-	for _, curLine := range setter.lines {
-		for _, curWord := range curLine.Words {
-			lineSize += len(curWord.Runes)
-		}
-		if curLine.BreakAfter { lineSize ++ }
-		index += lineSize
-		
+	metrics  := setter.face.Metrics()
+	lastLine := setter.lines[len(setter.lines) - 1]
+	for _, curLine := range setter.lines {	
 		if curLine.Y + metrics.Descent > position.Y {
-			line = curLine
+			lastLine = curLine
 			break
 		}
+		
+		index += curLine.Length()
 	}
-	index -= lineSize
 
-	if line.Words == nil { return }
+	if lastLine.Words == nil { return }
 
 	// find the first rune who's right bound is greater than position.X.
-	for _, curWord := range line.Words {
+	for _, curWord := range lastLine.Words {
 		for _, curChar := range curWord.Runes {
 			x := curWord.X + curChar.X + curChar.Width
 			if x > position.X { goto foundRune }
@@ -296,6 +301,20 @@ func (setter *TypeSetter) LayoutBoundsSpace () (image.Rectangle) {
 	return setter.layoutBoundsSpace
 }
 
+// MinimumSize returns the minimum width and height needed to display text. If
+// wrapping is enabled, this method will return (Em(), 0) 
+func (setter *TypeSetter) MinimumSize () image.Point {
+	setter.needLayout()
+	if setter.wrap {
+		return image.Pt(setter.Em().Round(), 0)
+	}
+
+	width  := setter.minWidth
+	height := fixed.Int26_6(len(setter.lines)) * setter.LineHeight()
+
+	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
 // typesetter's state.