Last visibile item in StackPanel is now clipped to maximum available area.

Generalised text fitting (to width) and implemented binary search.

addons/embedres/embedres.go

@@ -0,0 +1,24 @@
+package embedres
+
+import (
+	"embed"
+	"io"
+
+	"opslag.de/schobers/zntg/ui"
+)
+
+var _ ui.Resources = &resources{}
+
+type resources struct {
+	fs embed.FS
+}
+
+func New(fs embed.FS) ui.Resources {
+	return &resources{fs}
+}
+
+func (r resources) Destroy() error { return nil }
+
+func (r resources) OpenResource(name string) (io.ReadCloser, error) {
+	return r.fs.Open(name)
+}

ui/button.go

@@ -40,30 +40,30 @@ func BuildIconButton(icon, text string, fn func(b *Button)) *Button {
 }
 
 func (b *Button) desiredSize(ctx Context) geom.PointF32 {
-	var pad = ctx.Style().Dimensions.TextPadding
-	var font = b.Font_(ctx)
+	var pad = b.ActualTextPadding(ctx)
+	var font = b.ActualFont(ctx)
 	var w, h float32 = 0, font.Height()
 
 	icon, iconW, iconH := b.icon(ctx)
 	if len(b.Text) == 0 {
 		if icon != nil && iconH > 0 {
-			w = pad + iconW + pad
+			w = pad.Left + iconW + pad.Right
 			h = iconH
 		}
 	} else {
-		w += pad + font.WidthOf(b.Text) + pad
+		w += pad.Left + font.WidthOf(b.Text) + pad.Right
 		if icon != nil && iconH > 0 {
 			if b.IconHeight == 0 {
 				iconW = iconW * h / iconH
 				// iconH = h
 			}
-			w += iconW + pad
+			w += iconW + pad.Right
 		}
 	}
 	if w == 0 {
 		return geom.ZeroPtF32
 	}
-	return geom.PtF32(w, pad+h+pad)
+	return geom.PtF32(w, pad.Top+h+pad.Bottom)
 }
 
 func (b *Button) icon(ctx Context) (Texture, float32, float32) {
@@ -203,8 +203,8 @@ func (b *Button) Render(ctx Context) {
 	bounds.Min.X += .5 * deltaX
 	bounds.Min.Y += .5 * deltaY
 
-	var pad = style.Dimensions.TextPadding
-	bounds = bounds.Inset(pad)
+	pad := b.ActualTextPadding(ctx)
+	bounds = pad.InsetRect(bounds)
 	boundsH := bounds.Dy()
 	pos := bounds.Min
 	icon, iconW, iconH := b.icon(ctx)
@@ -222,10 +222,10 @@ func (b *Button) Render(ctx Context) {
 			iconOffsetY = .5 * (boundsH - iconH)
 		}
 		ctx.Renderer().DrawTextureOptions(icon, geom.RectRelF32(pos.X, pos.Y+iconOffsetY, iconW, iconH), DrawOptions{Tint: textColor})
-		pos.X += iconW + pad
+		pos.X += iconW + pad.Right
 	}
 	if len(b.Text) != 0 {
-		font := b.Font_(ctx)
+		font := b.ActualFont(ctx)
 		ctx.Renderer().Text(font, geom.PtF32(pos.X, pos.Y+.5*(boundsH-font.Height())), textColor, b.Text)
 	}
 

ui/checkbox.go

@@ -22,16 +22,16 @@ func BuildCheckbox(text string, fn func(c *Checkbox)) *Checkbox {
 }
 
 func (c *Checkbox) desiredSize(ctx Context) geom.PointF32 {
-	var pad = ctx.Style().Dimensions.TextPadding
-	font := c.Font_(ctx)
+	pad := c.ActualTextPadding(ctx)
+	font := c.ActualFont(ctx)
 	var w, h float32 = 0, font.Height()
 	if len(c.Text) != 0 {
-		w += pad + font.WidthOf(c.Text)
+		w += pad.Left + font.WidthOf(c.Text)
 	}
 	icon := c.getOrCreateNormalIcon(ctx)
 	_, iconWidth := ScaleToHeight(SizeOfTexture(icon).ToF32(), h)
-	w += pad + iconWidth
-	return geom.PtF32(w+pad, pad+h+pad)
+	w += pad.Left + iconWidth
+	return geom.PtF32(w+pad.Right, pad.Top+h+pad.Bottom)
 }
 
 func (c *Checkbox) icon(ctx Context) Texture {
@@ -108,8 +108,8 @@ func (c *Checkbox) Render(ctx Context) {
 	fore := c.TextColor(ctx)
 	bounds := c.bounds
 
-	var pad = style.Dimensions.TextPadding
-	bounds = bounds.Inset(pad)
+	pad := c.ActualTextPadding(ctx)
+	bounds = pad.InsetRect(bounds)
 	boundsH := bounds.Dy()
 	pos := bounds.Min
 	icon := c.icon(ctx)
@@ -125,10 +125,10 @@ func (c *Checkbox) Render(ctx Context) {
 		_, iconWidth := ScaleToHeight(SizeOfTexture(scaledIcon).ToF32(), boundsH)
 		rect := geom.RectRelF32(pos.X, pos.Y, iconWidth, boundsH)
 		ctx.Renderer().DrawTextureOptions(scaledIcon, rect, DrawOptions{Tint: iconColor})
-		pos.X += iconWidth + pad
+		pos.X += iconWidth + pad.Right
 	}
 	if len(c.Text) != 0 {
-		font := c.Font_(ctx)
+		font := c.ActualFont(ctx)
 		ctx.Renderer().Text(font, geom.PtF32(pos.X, pos.Y+.5*(boundsH-font.Height())), fore, c.Text)
 	}
 }

ui/controlbase.go

@@ -103,6 +103,7 @@ type ControlBase struct {
 	Background    color.Color
 	Font          FontStyle
 	TextAlignment HorizontalAlignment
+	TextPadding   SideLengths
 
 	Disabled bool
 
@@ -188,11 +189,15 @@ func (c *ControlBase) HandleNotify(ctx Context, e Event, notifier Notifier) bool
 	return false
 }
 
-func (c *ControlBase) Font_(ctx Context) Font {
+func (c *ControlBase) ActualFont(ctx Context) Font {
 	name := c.FontName(ctx)
 	return ctx.Fonts().Font(name)
 }
 
+func (c *ControlBase) ActualTextPadding(ctx Context) Sides {
+	return c.TextPadding.Zero(ctx.Style().Dimensions.TextPadding)
+}
+
 func (c *ControlBase) FontColor(ctx Context, color color.Color) color.Color {
 	if c.Disabled {
 		return ctx.Style().Palette.TextOnDisabled

ui/debug.go

@@ -77,8 +77,9 @@ func NewDebugOverlay(root Control) *debugOverlay {
 
 func (o *debugOverlay) renderControl(ctx Context, control Control) {
 	renderer := ctx.Renderer()
-	// bounds := control.Bounds()
-	// renderer.Rectangle(bounds, o.boundsColor, 1)
+
+	currentColor := zntg.MustHexColor("#FF0000")
+	parentColor := zntg.MustHexColor("#0000FF")
 
 	var maxY float32
 	var renderHoverNode func(pos geom.PointF32, node *controlNode)
@@ -96,6 +97,10 @@ func (o *debugOverlay) renderControl(ctx Context, control Control) {
 		renderer.FillRectangle(pos.RectRel2D(nameTextureWidth, nameTextureHeight), color.Black)
 		renderer.DrawTexturePoint(nameTexture, pos)
 		childPos := pos.Add2D(nameTextureWidth+ctx.Style().Dimensions.Margin, 0)
+		if len(node.Children) == 0 {
+			renderer.Rectangle(node.Parent.Bounds, parentColor, 1)
+			renderer.Rectangle(node.Bounds, currentColor, 1)
+		}
 		for _, child := range node.Children {
 			if childPos.Y == maxY {
 				childPos.Y = maxY + nameTextureHeight
@@ -114,15 +119,18 @@ func (o *debugOverlay) renderControl(ctx Context, control Control) {
 }
 
 func createHoverNodes(hover geom.PointF32, control Control) *controlNode {
-	if !hover.In(control.Bounds()) {
+	bounds := control.Bounds()
+	if !hover.In(bounds) {
 		return nil
 	}
-	node := &controlNode{Name: controlName(control)}
+	node := &controlNode{Name: controlName(control), Bounds: bounds}
 	for _, child := range controlChildren(control) {
 		childNode := createHoverNodes(hover, child)
-		if childNode != nil {
-			node.Children = append(node.Children, childNode)
+		if childNode == nil {
+			continue
 		}
+		childNode.Parent = node
+		node.Children = append(node.Children, childNode)
 	}
 	return node
 }
@@ -147,5 +155,7 @@ func (o *debugOverlay) Shown() {}
 
 type controlNode struct {
 	Name     string
+	Bounds   geom.RectangleF32
+	Parent   *controlNode
 	Children []*controlNode
 }

ui/label.go

@@ -6,10 +6,18 @@ import (
 	"opslag.de/schobers/geom"
 )
 
+type TextOverflow int
+
+const (
+	TextOverflowClip TextOverflow = iota
+	TextOverflowEllipsis
+)
+
 type Label struct {
 	ControlBase
 
 	Text         string
+	TextOverflow TextOverflow
 	DropShadow   color.Color
 
 	desired CachedValue
@@ -28,11 +36,11 @@ func (l *Label) hashDesiredSize(ctx Context) string {
 }
 
 func (l *Label) desiredSize(ctx Context) interface{} {
-	font := l.Font_(ctx)
+	font := l.ActualFont(ctx)
 	width := font.WidthOf(l.Text)
 	height := font.Height()
-	pad := ctx.Style().Dimensions.TextPadding
-	return geom.PtF32(width+pad*2, height+pad*2)
+	pad := l.ActualTextPadding(ctx)
+	return geom.PtF32(pad.Left+width+pad.Right, pad.Top+height+pad.Bottom)
 }
 
 func (l *Label) DesiredSize(ctx Context, _ geom.PointF32) geom.PointF32 {
@@ -40,8 +48,8 @@ func (l *Label) DesiredSize(ctx Context, _ geom.PointF32) geom.PointF32 {
 }
 
 func (l *Label) getLabelTopLeft(ctx Context) geom.PointF32 {
-	pad := ctx.Style().Dimensions.TextPadding
-	bounds := l.bounds.Inset(pad)
+	pad := l.ActualTextPadding(ctx)
+	bounds := pad.InsetRect(l.bounds)
 	switch l.TextAlignment {
 	case AlignRight:
 		return geom.PtF32(bounds.Max.X, bounds.Min.Y)
@@ -55,10 +63,15 @@ func (l *Label) getLabelTopLeft(ctx Context) geom.PointF32 {
 func (l *Label) Render(ctx Context) {
 	l.RenderBackground(ctx)
 	fontColor := l.TextColor(ctx)
-	fontName := l.FontName(ctx)
+	font := l.ActualFont(ctx)
 	topLeft := l.getLabelTopLeft(ctx)
-	if l.DropShadow != nil {
-		ctx.Fonts().TextAlign(fontName, topLeft.Add2D(1, 1), l.DropShadow, l.Text, l.TextAlignment)
+	text := l.Text
+	availableWidth := l.bounds.Dx()
+	if l.TextOverflow == TextOverflowEllipsis {
+		text = fitTextEllipsis(font, text, availableWidth)
 	}
-	ctx.Fonts().TextAlign(fontName, topLeft, fontColor, l.Text, l.TextAlignment)
+	if l.DropShadow != nil {
+		ctx.Renderer().TextAlign(font, topLeft.Add2D(1, 1), l.DropShadow, text, l.TextAlignment)
+	}
+	ctx.Renderer().TextAlign(font, topLeft, fontColor, text, l.TextAlignment)
 }

ui/length.go

@@ -24,9 +24,54 @@ func Fixed(l float32) *Length { return &Length{l} }
 
 func Infinite() *Length { return &Length{geom.NaN32()} }
 
+func ZL() *Length { return &Length{0} }
+
 type SideLengths struct {
 	Left   *Length
 	Top    *Length
 	Right  *Length
 	Bottom *Length
 }
+
+func (l SideLengths) InsetRect(r geom.RectangleF32) geom.RectangleF32 {
+	return Sides{
+		Left:   l.Left.Value(),
+		Top:    l.Top.Value(),
+		Right:  l.Right.Value(),
+		Bottom: l.Bottom.Value(),
+	}.InsetRect(r)
+}
+
+func (l SideLengths) Zero(value float32) Sides {
+	return Sides{
+		Left:   l.Left.Zero(value),
+		Top:    l.Top.Zero(value),
+		Right:  l.Right.Zero(value),
+		Bottom: l.Bottom.Zero(value),
+	}
+}
+
+type Sides struct {
+	Left   float32
+	Top    float32
+	Right  float32
+	Bottom float32
+}
+
+func (s Sides) InsetRect(r geom.RectangleF32) geom.RectangleF32 {
+	if r.Dx() < (s.Left + s.Right) {
+		r.Min.X += r.Dx() * s.Left / (s.Left + s.Right)
+		r.Max.X = r.Min.X
+	} else {
+		r.Min.X += s.Left
+		r.Max.X -= s.Right
+	}
+	if r.Dy() < (s.Top + s.Bottom) {
+		r.Min.Y += r.Dy() * s.Top / (s.Top + s.Bottom)
+		r.Max.Y = r.Min.Y
+	} else {
+		r.Min.Y += s.Top
+		r.Max.Y -= s.Bottom
+	}
+	return r
+}

ui/overflow.go

@@ -11,6 +11,9 @@ type overflow struct {
 
 	Background color.Color
 
+	ClipHorizontal bool
+	ClipVertical   bool
+
 	barWidth float32
 	desired  geom.PointF32
 	bounds   geom.RectangleF32
@@ -26,18 +29,30 @@ type overflow struct {
 type ScrollControl interface {
 	Control
 
+	SetBackgroundColor(color.Color)
+	SetClipHorizontal(bool)
+	SetClipVertical(bool)
 	SetScrollbarColor(bar color.Color, hover color.Color)
 }
 
+func BuildOverflow(content Control, build func(c ScrollControl)) ScrollControl {
+	o := &overflow{Proxy: Proxy{Content: content}}
+	o.hor = BuildScrollbar(OrientationHorizontal, func(*Scrollbar) {})
+	o.ver = BuildScrollbar(OrientationVertical, func(*Scrollbar) {})
+	if build != nil {
+		build(o)
+	}
+	return o
+}
+
 func Overflow(content Control) ScrollControl {
 	return OverflowBackground(content, nil)
 }
 
 func OverflowBackground(content Control, back color.Color) ScrollControl {
-	var o = &overflow{Proxy: Proxy{Content: content}, Background: back}
-	o.hor = BuildScrollbar(OrientationHorizontal, func(*Scrollbar) {})
-	o.ver = BuildScrollbar(OrientationVertical, func(*Scrollbar) {})
-	return o
+	return BuildOverflow(content, func(c ScrollControl) {
+		c.SetBackgroundColor(back)
+	})
 }
 
 func (o *overflow) shouldScroll(bounds geom.RectangleF32) (hor bool, ver bool) {
@@ -53,6 +68,8 @@ func (o *overflow) shouldScroll(bounds geom.RectangleF32) (hor bool, ver bool) {
 	if hor && !ver {
 		ver = scroll(size.Y+o.barWidth, bounds.Dy())
 	}
+	hor = hor && !o.ClipHorizontal
+	ver = ver && !o.ClipVertical
 	return
 }
 
@@ -158,6 +175,17 @@ func (o *overflow) Render(ctx Context) {
 		bar.Render(ctx)
 	})
 }
+func (o *overflow) SetBackgroundColor(c color.Color) {
+	o.Background = c
+}
+
+func (o *overflow) SetClipHorizontal(clip bool) {
+	o.ClipHorizontal = clip
+}
+
+func (o *overflow) SetClipVertical(clip bool) {
+	o.ClipVertical = clip
+}
 
 func (o *overflow) SetScrollbarColor(bar color.Color, hover color.Color) {
 	o.hor.BarColor = bar

ui/paragraph.go

@@ -26,11 +26,11 @@ func BuildParagraph(text string, fn func(*Paragraph)) *Paragraph {
 func fastFormatFloat32(f float32) string { return strconv.FormatFloat(float64(f), 'b', 32, 32) }
 
 func (p *Paragraph) desiredSize(ctx Context) interface{} {
-	font := p.Font_(ctx)
+	font := p.ActualFont(ctx)
 
-	pad := ctx.Style().Dimensions.TextPadding
-	lines := p.splitInLines(ctx, p.width-2*pad)
-	return geom.PtF32(p.width, float32(len(lines))*font.Height()+2*pad)
+	pad := p.ActualTextPadding(ctx)
+	lines := p.splitInLines(ctx, p.width-pad.Left-pad.Right)
+	return geom.PtF32(p.width, float32(len(lines))*font.Height()+pad.Top+pad.Bottom)
 }
 
 func (p *Paragraph) hashTextArranged(ctx Context) string {
@@ -42,38 +42,7 @@ func (p *Paragraph) hashTextDesired(ctx Context) string {
 }
 
 func (p *Paragraph) splitInLines(ctx Context, width float32) []string {
-	font := p.Font_(ctx)
-
-	spaces := func(s string) []int { // creates a slice with indices where spaces can be found in string s
-		var spaces []int
-		offset := 0
-		for {
-			space := strings.Index(s[offset:], " ")
-			if space == -1 {
-				return spaces
-			}
-			offset += space
-			spaces = append(spaces, offset)
-			offset++
-		}
-	}
-
-	fit := func(s string) string { // tries to fit as much of string s in width space.
-		if font.WidthOf(s) < width {
-			return s
-		}
-		spaces := spaces(s)
-		// removes one word (delimited by spaces) at a time and tries until the result fits.
-		for split := len(spaces) - 1; split >= 0; split-- {
-			clipped := s[:spaces[split]]
-			if font.WidthOf(clipped) < width {
-				return clipped
-			}
-		}
-		// nothing fits (returns the whole string)...
-		return s
-	}
-
+	font := p.ActualFont(ctx)
 	var lines []string
 	for _, line := range strings.Split(p.Text, "\n") {
 		if len(line) == 0 {
@@ -82,7 +51,7 @@ func (p *Paragraph) splitInLines(ctx Context, width float32) []string {
 		}
 
 		for len(line) > 0 {
-			clipped := fit(line)
+			clipped := fitTextWord(font, line, width)
 			lines = append(lines, clipped)
 			line = strings.TrimLeft(line[len(clipped):], " ")
 		}
@@ -91,8 +60,8 @@ func (p *Paragraph) splitInLines(ctx Context, width float32) []string {
 }
 
 func (p *Paragraph) updateLines(ctx Context) interface{} {
-	pad := ctx.Style().Dimensions.TextPadding
-	return p.splitInLines(ctx, p.Bounds().Dx()-2*pad)
+	pad := p.ActualTextPadding(ctx)
+	return p.splitInLines(ctx, p.Bounds().Dx()-pad.Left-pad.Right)
 }
 
 func (p *Paragraph) DesiredSize(ctx Context, size geom.PointF32) geom.PointF32 {
@@ -104,14 +73,14 @@ func (p *Paragraph) DesiredSize(ctx Context, size geom.PointF32) geom.PointF32 {
 func (p *Paragraph) Render(ctx Context) {
 	p.RenderBackground(ctx)
 
-	pad := ctx.Style().Dimensions.TextPadding
-	width := p.Bounds().Dx() - 2*pad
+	pad := p.ActualTextPadding(ctx)
+	width := p.Bounds().Dx() - pad.Left - pad.Right
 	lines := p.lines.GetContext(ctx, p.updateLines, p.hashTextArranged).([]string)
 
 	fontColor := p.TextColor(ctx)
 	fontName := p.FontName(ctx)
 	fontHeight := ctx.Fonts().Font(fontName).Height()
-	bounds := p.bounds.Inset(pad)
+	bounds := pad.InsetRect(p.bounds)
 
 	left := bounds.Min.X
 	switch p.TextAlignment {

ui/stackpanel.go

@@ -42,7 +42,9 @@ func (p *StackPanel) Arrange(ctx Context, bounds geom.RectangleF32, offset geom.
 				height = remainder / float32(stretch)
 			}
 		}
-		var child = geom.RectF32(bounds.Min.X, bounds.Min.Y+childOffset, bounds.Max.X, bounds.Min.Y+childOffset+height)
+		minY := geom.Min32(bounds.Max.Y, bounds.Min.Y+childOffset)
+		maxY := geom.Min32(bounds.Max.Y, bounds.Min.Y+childOffset+height)
+		var child = geom.RectF32(bounds.Min.X, minY, bounds.Max.X, maxY)
 		p.Children[i].Arrange(ctx, p.Orientation.FlipRect(child), offset, p)
 		childOffset += height
 	}

ui/text.go

@@ -0,0 +1,68 @@
+package ui
+
+import "strings"
+
+// findOptimalFit tries to find the optimal (largest) fit for the interval [0..n] by doing a binary search.
+func findOptimalFit(n int, fits func(i int) bool) int {
+	if n < 0 || fits(n) {
+		return n
+	}
+	min, max := 0, n
+	for {
+		if min == max {
+			if min == 0 && !fits(min) {
+				return -1
+			}
+			return min
+		}
+		middle := (max + min + 1) / 2
+		if fits(middle) {
+			min = middle
+		} else {
+			max = middle - 1
+		}
+	}
+}
+
+// findSpaces creates a slice with indices where spaces can be found in string s
+func findSpaces(s string) []int {
+	var spaces []int
+	offset := 0
+	for {
+		space := strings.Index(s[offset:], " ")
+		if space == -1 {
+			return spaces
+		}
+		offset += space
+		spaces = append(spaces, offset)
+		offset++
+	}
+}
+
+func fitTextEllipsis(font Font, text string, availableWidth float32) string {
+	if font.WidthOf(text) <= availableWidth {
+		return text
+	}
+	ellipsis := "..."
+	availableWidth -= font.WidthOf(ellipsis)
+	cut := findOptimalFit(len(text), func(i int) bool { return font.WidthOf(text[:i]) <= availableWidth })
+	if cut == -1 {
+		return ""
+	}
+	return text[:cut] + ellipsis
+}
+
+// fitTextWord tries to fit as much of string s in width space.
+func fitTextWord(font Font, s string, availableWidth float32) string {
+	if font.WidthOf(s) < availableWidth {
+		return s
+	}
+	spaces := findSpaces(s)
+	split := findOptimalFit(len(spaces)-1, func(i int) bool {
+		return font.WidthOf(s[:spaces[i]]) <= availableWidth
+	})
+	if split == -1 {
+		return s
+	}
+	return s[:spaces[split]]
+}

ui/textbox.go

@@ -49,21 +49,18 @@ func BuildTextBox(fn func(*TextBox)) *TextBox {
 	return b
 }
 
-func (b *TextBox) pad(ctx Context) float32 {
-	return ctx.Style().Dimensions.TextPadding
-}
-
 func (b *TextBox) Arrange(ctx Context, bounds geom.RectangleF32, offset geom.PointF32, parent Control) {
 	b.ControlBase.Arrange(ctx, bounds, offset, parent)
-	b.box.Arrange(ctx, bounds.Inset(b.pad(ctx)), offset, b)
+	pad := b.ActualTextPadding(ctx)
+	b.box.Arrange(ctx, pad.InsetRect(bounds), offset, b)
 }
 
 func (b *TextBox) DesiredSize(ctx Context, _ geom.PointF32) geom.PointF32 {
-	font := b.Font_(ctx)
+	font := b.ActualFont(ctx)
 	var width = font.WidthOf(b.Text)
 	var height = font.Height()
-	var pad = b.pad(ctx)
-	return geom.PtF32(width+pad*2, height+pad*2)
+	pad := b.ActualTextPadding(ctx)
+	return geom.PtF32(pad.Left+width+pad.Right, pad.Top+height+pad.Bottom)
 }
 
 func (b *TextBox) TextChanged() *Events { return &b.textChanged }
@@ -71,7 +68,7 @@ func (b *TextBox) TextChanged() *Events { return &b.textChanged }
 func (b *TextBox) mousePosToCaretPos(ctx Context, e MouseEvent) int {
 	p := b.ToControlPosition(e.Pos())
 	offset := p.X - b.box.bounds.Min.X
-	f := b.Font_(ctx)
+	f := b.ActualFont(ctx)
 	var carets = [3]int{0, 0, len(b.Text)}
 	var offsets = [3]float32{0, 0, f.WidthOf(b.Text)}
 	var updateCenter = func() {
@@ -262,7 +259,7 @@ func (b *TextBox) Render(ctx Context) {
 			back = ctx.Style().Palette.Background
 		}
 		renderer.Clear(back)
-		font := b.Font_(ctx)
+		font := b.ActualFont(ctx)
 		if b.Selection.Start != b.Selection.End {
 			left, right := font.WidthOf(b.Text[:b.Selection.Start]), font.WidthOf(b.Text[:b.Selection.End])
 			renderer.FillRectangle(geom.RectF32(left, 0, right, size.Y), style.Palette.PrimaryHighlight)