Don't invalidate ContainerBox's children when something is set

redundantly

README.md

@@ -1,3 +1,14 @@
 # x
 
-WIP X backend for Tomo.
+[![Go Reference](https://pkg.go.dev/badge/git.tebibyte.media/tomo/x.svg)](https://pkg.go.dev/git.tebibyte.media/tomo/x)
+
+An X11 backend for Tomo.
+
+## Installation
+
+```
+cd x/x
+go build -buildmode=plugin .
+mkdir -p ~/.local/lib/tomo/plugins
+mv x.so ~/.local/lib/tomo/plugins
+```

backend.go

@@ -48,9 +48,7 @@ func (backend *Backend) Run () error {
 		case <- pingQuit:
 			return nil // FIXME: if we exited due to an error say so
 		}
-		for _, window := range backend.windows {
-			window.afterEvent()
-		}
+		backend.afterEvent()
 	}
 }
 
@@ -78,3 +76,9 @@ func (backend *Backend) Do (callback func ()) {
 func (backend *Backend) assert () {
 	if backend == nil { panic("nil backend") }
 }
+
+func (backend *Backend) afterEvent () {
+	for _, window := range backend.windows {
+		window.afterEvent()
+	}
+}

box.go

@@ -3,6 +3,7 @@ package x
 import "image"
 import "image/color"
 import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/x/canvas"
 import "git.tebibyte.media/tomo/tomo/data"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/event"
@@ -13,12 +14,18 @@ type box struct {
 	parent   parent
 	outer    anyBox
 
-	bounds  image.Rectangle
-	minSize image.Point
+	bounds      image.Rectangle
+	minSize     image.Point
+	userMinSize image.Point
+	innerClippingBounds image.Rectangle
+	
+	minSizeQueued bool
+	focusQueued   *bool
 
 	padding tomo.Inset
 	border  []tomo.Border
 	color   color.Color
+	texture *xcanvas.Texture
 
 	dndData   data.Data
 	dndAccept []data.Mime
@@ -45,18 +52,28 @@ type box struct {
 	}
 }
 
-func (backend *Backend) NewBox() tomo.Box {
+func (backend *Backend) newBox (outer anyBox) *box {
 	box := &box {
 		backend: backend,
-		color:   color.White,
+		color:   color.Transparent,
+		outer:   outer,
+		drawer:  outer,
 	}
-	box.drawer = box
-	box.outer  = box
+	if outer == nil {
+		box.drawer = box
+		box.outer  = box
+	}
+	box.invalidateMinimum()
 	return box
 }
 
-func (this *box) Box () tomo.Box {
-	return this
+func (backend *Backend) NewBox() tomo.Box {
+	box := backend.newBox(nil)
+	return box
+}
+
+func (this *box) GetBox () tomo.Box {
+	return this.outer
 }
 
 func (this *box) Window () tomo.Window {
@@ -68,7 +85,7 @@ func (this *box) Bounds () image.Rectangle {
 }
 
 func (this *box) InnerBounds () image.Rectangle {
-	return this.padding.Apply(this.innerClippingBounds())
+	return this.padding.Apply(this.innerClippingBounds)
 }
 
 func (this *box) MinimumSize () image.Point {
@@ -86,10 +103,6 @@ func (this *box) borderSum () tomo.Inset {
 	return sum
 }
 
-func (this *box) innerClippingBounds () image.Rectangle {
-	return this.borderSum().Apply(this.bounds)
-}
-
 func (this *box) SetBounds (bounds image.Rectangle) {
 	if this.bounds == bounds { return }
 	this.bounds = bounds
@@ -97,31 +110,54 @@ func (this *box) SetBounds (bounds image.Rectangle) {
 }
 
 func (this *box) SetColor (c color.Color) {
+	if c == nil { c = color.Transparent }
 	if this.color == c { return }
 	this.color = c
 	this.invalidateDraw()
 }
 
-func (this *box) SetBorder (border ...tomo.Border) {
-	this.border = border
-	this.invalidateLayout()
-	this.recalculateMinimumSize()
+func (this *box) SetTexture (texture canvas.Texture) {
+	if this.texture == texture { return }
+	this.texture = xcanvas.AssertTexture(texture)
+	this.invalidateDraw()
+}
+
+func (this *box) SetBorder (borders ...tomo.Border) {
+	previousBorderSum := this.borderSum()
+	previousBorders   := this.border
+	this.border = borders
+
+	// only invalidate the layout if the border is sized differently
+	if this.borderSum() != previousBorderSum {
+		this.invalidateLayout()
+		this.invalidateMinimum()
+		return
+	}
+
+	// if the border takes up the same amount of space, only invalidate the
+	// drawing if it looks different
+	for index, newBorder := range this.border {
+		different :=
+			index >= len(previousBorders) ||
+			newBorder != previousBorders[index]
+		if different {
+			this.invalidateDraw()
+			return
+		}
+	}
 }
 
 func (this *box) SetMinimumSize (size image.Point) {
-	if this.minSize == size { return }
-	this.minSize = size
-	
-	if this.parent != nil {
-		this.parent.notifyMinimumSizeChange(this)
-	}
+	if this.userMinSize == size { return }
+	this.userMinSize = size
+	this.invalidateMinimum()
 }
 
 func (this *box) SetPadding (padding tomo.Inset) {
 	if this.padding == padding { return }
 	this.padding = padding
 	this.invalidateLayout()
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 }
 
 func (this *box) SetDNDData (dat data.Data) {
@@ -133,9 +169,11 @@ func (this *box) SetDNDAccept (types ...data.Mime) {
 }
 
 func (this *box) SetFocused (focused bool) {
-	if this.parent == nil { return }
-	window := this.parent.window()
-	if window == nil { return }
+	if this.parent == nil || this.parent.window () == nil {
+		focusedCopy := focused
+		this.focusQueued = &focusedCopy
+		return
+	}
 	if !this.focusable { return }
 	
 	if this.Focused () && !focused {
@@ -208,58 +246,154 @@ func (this *box) OnKeyDown (callback func(key input.Key, numberPad bool)) event.
 func (this *box) OnKeyUp (callback func(key input.Key, numberPad bool)) event.Cookie {
 	return this.on.keyUp.Connect(callback)
 }
+func (this *box) handleFocusEnter () {
+	this.on.focusEnter.Broadcast()
+}
+func (this *box) handleFocusLeave () {
+	this.on.focusLeave.Broadcast()
+}
+func (this *box) handleMouseEnter () {
+	this.on.mouseEnter.Broadcast()
+}
+func (this *box) handleMouseLeave () {
+	this.on.mouseLeave.Broadcast()
+}
+func (this *box) handleMouseMove () {
+	this.on.mouseMove.Broadcast()
+}
+func (this *box) handleMouseDown (button input.Button) {
+	if this.focusable {
+		this.SetFocused(true)
+	} else {
+		if this.parent == nil { return }
+		window := this.parent.window()
+		if window == nil { return }
+		window.focus(nil)
+	}
+	for _, listener := range this.on.mouseDown.Listeners() {
+		listener(button)
+	}
+}
+func (this *box) handleMouseUp (button input.Button) {
+	for _, listener := range this.on.mouseUp.Listeners() {
+		listener(button)
+	}
+}
+func (this *box) handleScroll (x, y float64) {
+	for _, listener := range this.on.scroll.Listeners() {
+		listener(x, y)
+	}
+}
+func (this *box) handleKeyDown (key input.Key, numberPad bool) {
+	for _, listener := range this.on.keyDown.Listeners() {
+		listener(key, numberPad)
+	}
+}
+func (this *box) handleKeyUp (key input.Key, numberPad bool) {
+	for _, listener := range this.on.keyUp.Listeners() {
+		listener(key, numberPad)
+	}
+}
 // -------------------------------------------------------------------------- //
 
 func (this *box) Draw (can canvas.Canvas) {
 	if can == nil { return }
 	pen := can.Pen()
 	pen.Fill(this.color)
-	pen.Rectangle(this.bounds)
+	pen.Texture(this.texture)
+	
+	if this.transparent() && this.parent != nil {
+		this.parent.drawBackgroundPart(can)
+	}
+	pen.Rectangle(this.Bounds())
 }
 
 func (this *box) drawBorders (can canvas.Canvas) {
 	if can == nil { return }
 	pen := can.Pen()
 	bounds := this.bounds
+
+	rectangle := func (x0, y0, x1, y1 int, c color.Color) {
+		area := image.Rect(x0, y0, x1, y1)
+		if transparent(c) && this.parent != nil {
+			this.parent.drawBackgroundPart(can.Clip(area))
+		}
+		pen.Fill(c)
+		pen.Rectangle(area)
+	}
+	
 	for _, border := range this.border {
-		pen.Fill(border.Color[tomo.SideTop])
-		pen.Rectangle(image.Rect (
+		rectangle (
 			bounds.Min.X,
 			bounds.Min.Y,
 			bounds.Max.X,
-			bounds.Min.Y + border.Width[tomo.SideTop]))
-		pen.Fill(border.Color[tomo.SideBottom])
-		pen.Rectangle(image.Rect (
+			bounds.Min.Y + border.Width[tomo.SideTop],
+			border.Color[tomo.SideTop])
+		rectangle (
 			bounds.Min.X,
 			bounds.Max.Y - border.Width[tomo.SideBottom],
 			bounds.Max.X,
-			bounds.Max.Y))
-		pen.Fill(border.Color[tomo.SideLeft])
-		pen.Rectangle(image.Rect (
+			bounds.Max.Y,
+			border.Color[tomo.SideBottom])
+		rectangle (
 			bounds.Min.X,
 			bounds.Min.Y + border.Width[tomo.SideTop],
 			bounds.Min.X + border.Width[tomo.SideLeft],
-			bounds.Max.Y - border.Width[tomo.SideBottom]))
-		pen.Fill(border.Color[tomo.SideRight])
-		pen.Rectangle(image.Rect (
+			bounds.Max.Y - border.Width[tomo.SideBottom],
+			border.Color[tomo.SideLeft])
+		rectangle (
 			bounds.Max.X - border.Width[tomo.SideRight],
 			bounds.Min.Y + border.Width[tomo.SideTop],
 			bounds.Max.X,
-			bounds.Max.Y - border.Width[tomo.SideBottom]))
+			bounds.Max.Y - border.Width[tomo.SideBottom],
+			border.Color[tomo.SideRight])
 
 		bounds = border.Width.Apply(bounds)
 	}
 }
 
-func (this *box) doDraw () {
-	if this.canvas == nil { return }
-	if this.drawer != nil {
-		this.drawBorders(this.canvas)
-		this.drawer.Draw(this.canvas.Clip(this.innerClippingBounds()))
+func (this *box) contentMinimum () image.Point {
+	var minimum image.Point
+	minimum.X += this.padding.Horizontal()
+	minimum.Y += this.padding.Vertical()
+	borderSum := this.borderSum()
+	minimum.X += borderSum.Horizontal()
+	minimum.Y += borderSum.Vertical()
+	return minimum
+}
+
+func (this *box) doMinimumSize () {
+	this.minSize = this.outer.contentMinimum()
+	if this.minSize.X < this.userMinSize.X {
+		this.minSize.X = this.userMinSize.X
+	}
+	if this.minSize.Y < this.userMinSize.Y {
+		this.minSize.Y = this.userMinSize.Y
+	}
+	
+	if this.parent != nil {
+		this.parent.notifyMinimumSizeChange(this)
 	}
 }
 
+// var drawcnt int
+func (this *box) doDraw () {
+	// println("DRAW", drawcnt)
+	// drawcnt ++
+	
+	if this.canvas == nil { return }
+	if this.drawer != nil {
+		this.drawBorders(this.canvas)
+		this.drawer.Draw(this.canvas.Clip(this.innerClippingBounds))
+	}
+}
+
+// var laycnt int
 func (this *box) doLayout () {
+	// println("LAYOUT", laycnt)
+	// laycnt ++
+	
+	this.innerClippingBounds = this.borderSum().Apply(this.bounds)
 	if this.parent == nil { this.canvas = nil; return  }
 	parentCanvas := this.parent.canvas()
 	if parentCanvas == nil { this.canvas = nil; return }
@@ -273,6 +407,21 @@ func (this *box) setParent (parent parent) {
 	this.parent = parent
 }
 
+func (this *box) getParent () parent {
+	return this.parent
+}
+
+func (this *box) flushActionQueue () {
+	if this.parent == nil || this.parent.window() == nil { return }
+
+	if this.minSizeQueued {
+		this.invalidateMinimum()
+	}
+	if this.focusQueued != nil {
+		this.SetFocused(*this.focusQueued)
+	}
+}
+
 func (this *box) recursiveRedo () {
 	this.doLayout()
 	this.doDraw()
@@ -288,17 +437,19 @@ func (this *box) invalidateDraw () {
 	this.parent.window().invalidateDraw(this.outer)
 }
 
-func (this *box) recalculateMinimumSize () {
-	if this.outer != anyBox(this) {
-		this.outer.recalculateMinimumSize()
+func (this *box) invalidateMinimum () {
+	if this.parent == nil || this.parent.window() == nil {
+		this.minSizeQueued = true
+		return
 	}
+	this.parent.window().invalidateMinimum(this.outer)
 }
 
 func (this *box) canBeFocused () bool {
 	return this.focusable
 }
 
-func (this *box) boxUnder (point image.Point) anyBox {
+func (this *box) boxUnder (point image.Point, category eventCategory) anyBox {
 	if point.In(this.bounds) {
 		return this.outer
 	} else {
@@ -306,62 +457,15 @@ func (this *box) boxUnder (point image.Point) anyBox {
 	}
 }
 
-func (this *box) handleFocusEnter () {
-	this.on.focusEnter.Broadcast()
-}
-
-func (this *box) handleFocusLeave () {
-	this.on.focusLeave.Broadcast()
-}
-
-func (this *box) handleMouseEnter () {
-	this.on.mouseEnter.Broadcast()
-}
-
-func (this *box) handleMouseLeave () {
-	this.on.mouseLeave.Broadcast()
-}
-
-func (this *box) handleMouseMove () {
-	this.on.mouseMove.Broadcast()
-}
-
-func (this *box) handleMouseDown (button input.Button) {
-	if this.focusable {
-		this.SetFocused(true)
-	} else {
-		if this.parent == nil { return }
-		window := this.parent.window()
-		if window == nil { return }
-		window.focus(nil)
-	}
-	for _, listener := range this.on.mouseDown.Listeners() {
-		listener(button)
-	}
-}
-
-func (this *box) handleMouseUp (button input.Button) {
-	for _, listener := range this.on.mouseUp.Listeners() {
-		listener(button)
-	}
-}
-
-func (this *box) handleKeyDown (key input.Key, numberPad bool) {
-	for _, listener := range this.on.keyDown.Listeners() {
-		listener(key, numberPad)
-	}
-}
-
-func (this *box) handleKeyUp (key input.Key, numberPad bool) {
-	for _, listener := range this.on.keyUp.Listeners() {
-		listener(key, numberPad)
-	}
-}
-
 func (this *box) propagate (callback func (anyBox) bool) bool {
-	return callback(this)
+	return callback(this.outer)
 }
 
 func (this *box) propagateAlt (callback func (anyBox) bool) bool {
-	return callback(this)
+	return callback(this.outer)
+}
+
+func (this *box) transparent () bool {
+	return transparent(this.color) &&
+		(this.texture == nil || !this.texture.Opaque())
 }

canvas/canvas.go

@@ -4,22 +4,23 @@ import "image"
 import "image/color"
 import "github.com/jezek/xgbutil"
 import "github.com/jezek/xgb/xproto"
-import "git.tebibyte.media/tomo/ggfx"
 import "github.com/jezek/xgbutil/xgraphics"
 import "git.tebibyte.media/tomo/tomo/canvas"
 
 // Canvas satisfies the canvas.Canvas interface. It draws to an xgraphics.Image.
+// It must be closed after use.
 type Canvas struct {
 	*xgraphics.Image
 }
 
-// New creates a new canvas from a bounding rectangle.
-func New (x *xgbutil.XUtil, bounds image.Rectangle) *Canvas {
-	return NewFrom(xgraphics.New(x, bounds))
+// NewCanvas creates a new canvas from a bounding rectangle.
+func NewCanvas (x *xgbutil.XUtil, bounds image.Rectangle) *Canvas {
+	return NewCanvasFrom(xgraphics.New(x, bounds))
 }
 
-// NewFrom creates a new canvas from an existing xgraphics.Image.
-func NewFrom (image *xgraphics.Image) *Canvas {
+// NewCanvasFrom creates a new canvas from an existing xgraphics.Image. Note
+// that calling Close() on the resulting canvas will destroy this image.
+func NewCanvasFrom (image *xgraphics.Image) *Canvas {
 	if image == nil { return nil }
 	return &Canvas { image }
 }
@@ -28,12 +29,6 @@ func NewFrom (image *xgraphics.Image) *Canvas {
 func (this *Canvas) Pen () canvas.Pen {
 	return &pen {
 		image: this.Image,
-		gfx:   ggfx.Image[uint8] {
-			Pix:    this.Image.Pix,
-			Stride: this.Image.Stride,
-			Rect:   this.Image.Rect,
-			Width:  4,
-		},
 	}
 }
 
@@ -53,6 +48,12 @@ func (this *Canvas) Push (window xproto.Window) {
 	this.XExpPaint(window, this.Bounds().Min.X, this.Bounds().Min.Y)
 }
 
+// Close frees this canvas from the X server.
+func (this *Canvas) Close () {
+	this.assert()
+	this.Image.Destroy()
+}
+
 func (this *Canvas) assert () {
 	if this == nil { panic("nil canvas") }
 }
@@ -64,50 +65,69 @@ func (this *Canvas) assert () {
 
 type pen struct {
 	image *xgraphics.Image
-	gfx    ggfx.Image[uint8]
 
-	closed bool
-	endCap canvas.Cap
-	joint  canvas.Joint
-	weight int
-	align  canvas.StrokeAlign
-	stroke [4]uint8
-	fill   [4]uint8
+	closed  bool
+	endCap  canvas.Cap
+	joint   canvas.Joint
+	weight  int
+	align   canvas.StrokeAlign
+	stroke  xgraphics.BGRA
+	fill    xgraphics.BGRA
+	texture *Texture
 }
 
 func (this *pen) Rectangle (bounds image.Rectangle) {
+	bounds = bounds.Canon()
 	if this.weight == 0 {
-		this.gfx.FillRectangle(this.fill[:], bounds)
+		if this.fill.A > 0 && !this.textureObscures() {
+			this.fillRectangle(this.fill, bounds)
+		}
+		if this.texture != nil {
+			this.textureRectangle(bounds)
+		}
 	} else {
-		this.gfx.StrokeRectangle(this.stroke[:], this.weight, bounds)
+		if this.stroke.A > 0 {
+			this.strokeRectangle(this.stroke, bounds)
+		}
 	}
 }
 
 func (this *pen) Path (points ...image.Point) {
 	if this.weight == 0 {
-		this.gfx.FillPolygon(this.fill[:], points...)
-	} else if this.closed {
-		this.gfx.StrokePolygon(this.stroke[:], this.weight, points...)
+		if this.fill.A > 0 {
+			this.fillPolygon(this.fill, points...)
+		}
+	} else if this.closed && len(points) > 2 {
+		if this.stroke.A > 0 {
+			this.strokePolygon(this.stroke, points...)
+		}
 	} else {
-		this.gfx.PolyLine(this.stroke[:], this.weight, points...)
+		if this.stroke.A > 0 {
+			this.polyLine(this.stroke, points...)
+		}
 	}
 }
- 
+
 func (this *pen) Closed       (closed bool)              { this.closed = closed }
 func (this *pen) Cap          (endCap canvas.Cap)        { this.endCap = endCap }
 func (this *pen) Joint        (joint  canvas.Joint)      { this.joint  = joint  }
 func (this *pen) StrokeWeight (weight int)               { this.weight = weight }
 func (this *pen) StrokeAlign  (align canvas.StrokeAlign) { this.align  = align  }
 
-func (this *pen) Stroke (stroke color.Color) { this.stroke = convertColor(stroke) }
-func (this *pen) Fill (fill color.Color)     { this.fill   = convertColor(fill)   }
+func (this *pen) Stroke  (stroke color.Color)     { this.stroke  = convertColor(stroke)   }
+func (this *pen) Fill    (fill color.Color)       { this.fill    = convertColor(fill)     }
+func (this *pen) Texture (texture canvas.Texture) { this.texture = AssertTexture(texture) }
 
-func convertColor (c color.Color) [4]uint8 {
+func (this *pen) textureObscures () bool {
+	return this.texture != nil && this.texture.Opaque()
+}
+
+func convertColor (c color.Color) xgraphics.BGRA {
 	r, g, b, a := c.RGBA()
-	return [4]uint8 {
-		uint8(b >> 8),
-		uint8(g >> 8),
-		uint8(r >> 8),
-		uint8(a >> 8),
+	return xgraphics.BGRA {
+		B: uint8(b >> 8),
+		G: uint8(g >> 8),
+		R: uint8(r >> 8),
+		A: uint8(a >> 8),
 	}
 }

canvas/draw.go

@@ -0,0 +1,296 @@
+package xcanvas
+
+import "sort"
+import "image"
+import "github.com/jezek/xgbutil/xgraphics"
+
+func (this *pen) textureRectangle (bounds image.Rectangle) {
+	if this.texture.Opaque() {
+		this.textureRectangleOpaque(bounds)
+	} else {
+		this.textureRectangleTransparent(bounds)
+	}
+}
+
+func (this *pen) textureRectangleOpaque (bounds image.Rectangle) {
+	dstBounds := bounds.Intersect(this.image.Bounds())
+	var pos image.Point
+
+	dst := this.image.Pix
+	src := this.texture.pix
+	offset := this.texture.rect.Min.Sub(bounds.Min)
+
+	for pos.Y = dstBounds.Min.Y; pos.Y < dstBounds.Max.Y; pos.Y ++ {
+	for pos.X = dstBounds.Min.X; pos.X < dstBounds.Max.X; pos.X ++ {
+		srcPos := pos.Add(offset)
+		dstIndex := this.image.PixOffset(pos.X, pos.Y)
+		srcIndex := this.texture.PixOffset(srcPos.X, srcPos.Y)
+		dst[dstIndex + 0] = src[srcIndex + 0]
+		dst[dstIndex + 1] = src[srcIndex + 1]
+		dst[dstIndex + 2] = src[srcIndex + 2]
+		dst[dstIndex + 3] = src[srcIndex + 3]
+	}}
+}
+
+func (this *pen) textureRectangleTransparent (bounds image.Rectangle) {
+	dstBounds := bounds.Intersect(this.image.Bounds())
+	var pos image.Point
+
+	dst := this.image.Pix
+	src := this.texture.pix
+	offset := this.texture.rect.Min.Sub(bounds.Min)
+
+	for pos.Y = dstBounds.Min.Y; pos.Y < dstBounds.Max.Y; pos.Y ++ {
+	for pos.X = dstBounds.Min.X; pos.X < dstBounds.Max.X; pos.X ++ {
+		srcPos := pos.Add(offset)
+		dstIndex := this.image.PixOffset(pos.X, pos.Y)
+		srcIndex := this.texture.PixOffset(srcPos.X, srcPos.Y)
+		pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+			B: dst[dstIndex + 0],
+			G: dst[dstIndex + 1],
+			R: dst[dstIndex + 2],
+			A: dst[dstIndex + 3],
+		}, xgraphics.BGRA {
+			B: src[srcIndex + 0],
+			G: src[srcIndex + 1],
+			R: src[srcIndex + 2],
+			A: src[srcIndex + 3],
+		})
+		dst[dstIndex + 0] = pixel.B
+		dst[dstIndex + 1] = pixel.G
+		dst[dstIndex + 2] = pixel.R
+		dst[dstIndex + 3] = pixel.A
+	}}
+}
+
+func (this *pen) fillRectangle (c xgraphics.BGRA, bounds image.Rectangle) {
+	if c.A == 255 {
+		this.fillRectangleOpaque(c, bounds)
+	} else {
+		this.fillRectangleTransparent(c, bounds)
+	}
+}
+
+func (this *pen) fillRectangleOpaque (c xgraphics.BGRA, bounds image.Rectangle) {
+	bounds = bounds.Intersect(this.image.Bounds())
+	var pos image.Point
+
+	for pos.Y = bounds.Min.Y; pos.Y < bounds.Max.Y; pos.Y ++ {
+	for pos.X = bounds.Min.X; pos.X < bounds.Max.X; pos.X ++ {
+		index := this.image.PixOffset(pos.X, pos.Y)
+		this.image.Pix[index + 0] = c.B
+		this.image.Pix[index + 1] = c.G
+		this.image.Pix[index + 2] = c.R
+		this.image.Pix[index + 3] = c.A
+	}}
+}
+
+func (this *pen) fillRectangleTransparent (c xgraphics.BGRA, bounds image.Rectangle) {
+	bounds = bounds.Intersect(this.image.Bounds())
+	var pos image.Point
+
+	for pos.Y = bounds.Min.Y; pos.Y < bounds.Max.Y; pos.Y ++ {
+	for pos.X = bounds.Min.X; pos.X < bounds.Max.X; pos.X ++ {
+		index := this.image.PixOffset(pos.X, pos.Y)
+		pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+			B: this.image.Pix[index + 0],
+			G: this.image.Pix[index + 1],
+			R: this.image.Pix[index + 2],
+			A: this.image.Pix[index + 3],
+		}, c)
+		this.image.Pix[index + 0] = pixel.B
+		this.image.Pix[index + 1] = pixel.G
+		this.image.Pix[index + 2] = pixel.R
+		this.image.Pix[index + 3] = pixel.A
+	}}
+}
+
+func (this *pen) strokeRectangle (c xgraphics.BGRA, bounds image.Rectangle) {
+	if this.weight > bounds.Dx() / 2 || this.weight > bounds.Dy() / 2 {
+		this.fillRectangle(c, bounds)
+		return
+	}
+
+	top := image.Rect (
+		bounds.Min.X,
+		bounds.Min.Y,
+		bounds.Max.X,
+		bounds.Min.Y + this.weight)
+	bottom := image.Rect (
+		bounds.Min.X,
+		bounds.Max.Y - this.weight,
+		bounds.Max.X,
+		bounds.Max.Y)
+	left := image.Rect (
+		bounds.Min.X,
+		bounds.Min.Y + this.weight,
+		bounds.Min.X + this.weight,
+		bounds.Max.Y - this.weight)
+	right := image.Rect (
+		bounds.Max.X - this.weight,
+		bounds.Min.Y + this.weight,
+		bounds.Max.X,
+		bounds.Max.Y - this.weight)
+
+	this.fillRectangle(c, top,)
+	this.fillRectangle(c, bottom,)
+	this.fillRectangle(c, left,)
+	this.fillRectangle(c, right,)
+}
+
+// the polygon filling algorithm is adapted from:
+// https://www.alienryderflex.com/polygon_fill/
+// (if you write C like that i will disassemble you)
+
+func (this *pen) fillPolygon (c xgraphics.BGRA, points ...image.Point) {
+	if len(points) < 3 { return }
+
+	// figure out the bounds of the polygon so we don't test empty space
+	var area image.Rectangle
+	area.Min = points[0]
+	area.Max = points[0]
+	for _, point := range points[1:] {
+		if point.X < area.Min.X { area.Min.X = point.X }
+		if point.Y < area.Min.Y { area.Min.Y = point.Y }
+		if point.X > area.Max.X { area.Max.X = point.X }
+		if point.Y > area.Max.Y { area.Max.Y = point.Y }
+	}
+	area = this.image.Bounds().Intersect(area)
+	if area.Empty() { return }
+
+	context := fillingContext {
+		image:      this.image,
+		color:      this.fill,
+		min:        area.Min.X,
+		max:        area.Max.X,
+		boundaries: make([]int, len(points)),
+		points:     points,
+	}
+
+	for context.y = area.Min.Y; context.y < area.Max.Y; context.y ++ {
+		// build boundary list
+		boundaryCount := 0
+		prevPoint := points[len(points) - 1]
+		for _, point := range points {
+			fy      := float64(context.y)
+			fPointX := float64(point.X)
+			fPointY := float64(point.Y)
+			fPrevX  := float64(prevPoint.X)
+			fPrevY  := float64(prevPoint.Y)
+			addboundary :=
+				(fPointY < fy && fPrevY  >= fy) ||
+				(fPrevY  < fy && fPointY >= fy)
+			if addboundary {
+				context.boundaries[boundaryCount] = int (
+					fPointX +
+					(fy - fPointY) /
+					(fPrevY - fPointY) *
+					(fPrevX - fPointX))
+				boundaryCount ++
+			}
+			prevPoint = point
+		}
+
+		// sort boundary list
+		cutBoundaries := context.boundaries[:boundaryCount]
+		sort.Ints(cutBoundaries)
+
+		// fill pixels between boundary pairs
+		if c.A == 255 {
+			context.fillPolygonHotOpaque()
+		} else {
+			context.fillPolygonHotTransparent()
+		}
+	}
+
+}
+
+type fillingContext struct {
+	image      *xgraphics.Image
+	color      xgraphics.BGRA
+	min, max   int
+	y          int
+	boundaries []int
+	points     []image.Point
+}
+
+func (context *fillingContext) fillPolygonHotOpaque () {
+	for index := 0; index < len(context.boundaries); index += 2 {
+		left  := context.boundaries[index]
+		right := context.boundaries[index + 1]
+
+		// stop if we have exited the polygon
+		if left >= context.max { break }
+		// begin filling if we are within the polygon
+		if right > context.min {
+			// constrain boundaries to image size
+			if left  < context.min { left  = context.min }
+			if right > context.max { right = context.max }
+
+			// fill pixels in between
+			for x := left; x < right; x ++ {
+				index := context.image.PixOffset(x, context.y)
+				context.image.Pix[index + 0] = context.color.B
+				context.image.Pix[index + 1] = context.color.G
+				context.image.Pix[index + 2] = context.color.R
+				context.image.Pix[index + 3] = context.color.A
+			}
+		}
+	}
+}
+
+func (context *fillingContext) fillPolygonHotTransparent () {
+	for index := 0; index < len(context.boundaries); index += 2 {
+		left  := context.boundaries[index]
+		right := context.boundaries[index + 1]
+
+		// stop if we have exited the polygon
+		if left >= context.max { break }
+		// begin filling if we are within the polygon
+		if right > context.min {
+			// constrain boundaries to image size
+			if left  < context.min { left  = context.min }
+			if right > context.max { right = context.max }
+
+			// fill pixels in between
+			for x := left; x < right; x ++ {
+				index := context.image.PixOffset(x, context.y)
+				pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+					B: context.image.Pix[index + 0],
+					G: context.image.Pix[index + 1],
+					R: context.image.Pix[index + 2],
+					A: context.image.Pix[index + 3],
+				}, context.color)
+				context.image.Pix[index + 0] = pixel.B
+				context.image.Pix[index + 1] = pixel.G
+				context.image.Pix[index + 2] = pixel.R
+				context.image.Pix[index + 3] = pixel.A
+			}
+		}
+	}
+}
+
+func (this *pen) strokePolygon (c xgraphics.BGRA, points ...image.Point) {
+	prevPoint := points[len(points) - 1]
+	for _, point := range points {
+		this.line(c, prevPoint, point)
+		prevPoint = point
+	}
+}
+
+func (this *pen) polyLine (c xgraphics.BGRA, points ...image.Point) {
+	if len(points) < 2 { return }
+	prevPoint := points[0]
+	for _, point := range points[1:] {
+		this.line(c, prevPoint, point)
+		prevPoint = point
+	}
+}
+
+func wrap (n, min, max int) int {
+	max -= min
+	n   -= min
+	n   %= max
+	if n < 0 { n += max }
+	return n + min
+}

canvas/line.go

@@ -0,0 +1,95 @@
+package xcanvas
+
+import "image"
+import "github.com/jezek/xgbutil/xgraphics"
+
+// TODO: clip the line to the bounds
+func (this *pen) line  (
+	c      xgraphics.BGRA,
+	min    image.Point,
+	max    image.Point,
+) {
+	context := linePlottingContext {
+		plottingContext: plottingContext {
+			image:  this.image,
+			color:  c,
+			weight: this.weight,
+		},
+		min: min,
+		max: max,
+	}
+
+	if abs(max.Y - min.Y) < abs(max.X - min.X) {
+		if max.X < min.X { context.swap() }
+		context.lineLow()
+
+	} else {
+		if max.Y < min.Y { context.swap() }
+		context.lineHigh()
+	}
+}
+
+type linePlottingContext struct {
+	plottingContext
+	min image.Point
+	max image.Point
+}
+
+func (context *linePlottingContext) swap () {
+	temp := context.max
+	context.max = context.min
+	context.min = temp
+}
+
+func (context linePlottingContext) lineLow () {
+	deltaX := context.max.X - context.min.X
+	deltaY := context.max.Y - context.min.Y
+	yi     := 1
+
+	if deltaY < 0 {
+		yi      = -1
+		deltaY *= -1
+	}
+
+	D := (2 * deltaY) - deltaX
+	point := context.min
+
+	for ; point.X < context.max.X; point.X ++ {
+		context.plot(point)
+		if D > 0 {
+			D += 2 * (deltaY - deltaX)
+			point.Y += yi
+		} else {
+			D += 2 * deltaY
+		}
+	}
+}
+
+func (context linePlottingContext) lineHigh () {
+	deltaX := context.max.X - context.min.X
+	deltaY := context.max.Y - context.min.Y
+	xi     := 1
+
+	if deltaX < 0 {
+		xi      = -1
+		deltaX *= -1
+	}
+
+	D := (2 * deltaX) - deltaY
+	point := context.min
+
+	for ; point.Y < context.max.Y; point.Y ++ {
+		context.plot(point)
+		if D > 0 {
+			point.X += xi
+			D += 2 * (deltaX - deltaY)
+		} else {
+			D += 2 * deltaX
+		}
+	}
+}
+
+func abs (n int) int {
+	if n < 0 { n *= -1}
+	return n
+}

canvas/plot.go

@@ -0,0 +1,47 @@
+package xcanvas
+
+import "image"
+import "github.com/jezek/xgbutil/xgraphics"
+
+type plottingContext struct {
+	image  *xgraphics.Image
+	color  xgraphics.BGRA
+	weight int
+}
+
+func (context plottingContext) square (center image.Point) (square image.Rectangle) {
+	return image.Rect(0, 0, context.weight, context.weight).
+		Sub(image.Pt(context.weight / 2, context.weight / 2)).
+		Add(center).
+		Intersect(context.image.Bounds())
+}
+
+func (context plottingContext) plot (center image.Point) {
+	square := context.square(center)
+
+	if context.color.A == 255 {
+		for y := square.Min.Y; y < square.Max.Y; y ++ {
+		for x := square.Min.X; x < square.Max.X; x ++ {
+			index := context.image.PixOffset(x, y)
+			context.image.Pix[index + 0] = context.color.B
+			context.image.Pix[index + 1] = context.color.G
+			context.image.Pix[index + 2] = context.color.R
+			context.image.Pix[index + 3] = context.color.A
+		}}
+	} else {
+		for y := square.Min.Y; y < square.Max.Y; y ++ {
+		for x := square.Min.X; x < square.Max.X; x ++ {
+			index := context.image.PixOffset(x, y)
+			pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+				B: context.image.Pix[index + 0],
+				G: context.image.Pix[index + 1],
+				R: context.image.Pix[index + 2],
+				A: context.image.Pix[index + 3],
+			}, context.color)
+			context.image.Pix[index + 0] = pixel.B
+			context.image.Pix[index + 1] = pixel.G
+			context.image.Pix[index + 2] = pixel.R
+			context.image.Pix[index + 3] = pixel.A
+		}}
+	}
+}

canvas/texture.go

@@ -0,0 +1,106 @@
+package xcanvas
+
+import "image"
+import "image/color"
+import "github.com/jezek/xgbutil/xgraphics"
+import "git.tebibyte.media/tomo/tomo/canvas"
+
+// Texture is a read-only image texture that can be quickly written to a canvas.
+// It must be closed manually after use.
+type Texture struct {
+	pix         []uint8
+	stride      int
+	rect        image.Rectangle
+	transparent bool
+}
+
+// NewTextureFrom creates a new texture from a source image.
+func NewTextureFrom (source image.Image) *Texture {
+	bounds := source.Bounds()
+	texture := &Texture {
+		pix:    make([]uint8, bounds.Dx() * bounds.Dy() * 4),
+		stride: bounds.Dx() * 4,
+		rect:   bounds.Sub(bounds.Min),
+	}
+
+	index := 0
+	var point image.Point
+	for point.Y = bounds.Min.Y; point.Y < bounds.Max.Y; point.Y ++ {
+	for point.X = bounds.Min.X; point.X < bounds.Max.X; point.X ++ {
+		r, g, b, a := source.At(point.X, point.Y).RGBA()
+		texture.pix[index + 0] = uint8(b >> 8)
+		texture.pix[index + 1] = uint8(g >> 8)
+		texture.pix[index + 2] = uint8(r >> 8)
+		texture.pix[index + 3] = uint8(a >> 8)
+		index += 4
+
+		if a != 0xFFFF {
+			texture.transparent = true
+		}
+	}}
+
+	return texture
+}
+
+func (this *Texture) BGRAAt (x, y int) xgraphics.BGRA {
+	if !(image.Point{ x, y }.In(this.rect)) {
+		return xgraphics.BGRA { }
+	}
+	index := this.PixOffset(x, y)
+	return xgraphics.BGRA {
+		B: this.pix[index    ],
+		G: this.pix[index + 1],
+		R: this.pix[index + 2],
+		A: this.pix[index + 3],
+	}
+}
+
+func (this *Texture) At (x, y int) color.Color {
+	return this.BGRAAt(x, y)
+}
+
+// Bounds returns the bounding rectangle of this texture.
+func (this *Texture) Bounds () image.Rectangle {
+	return this.rect
+}
+
+func (this *Texture) ColorModel () color.Model {
+	return xgraphics.BGRAModel
+}
+
+// Opaque reports whether or not the texture is fully opaque.
+func (this *Texture) Opaque () bool {
+	return !this.transparent
+}
+
+func (this *Texture) PixOffset (x, y int) int {
+	x = wrap(x, this.rect.Min.X, this.rect.Max.X)
+	y = wrap(y, this.rect.Min.Y, this.rect.Max.Y)
+	return x * 4 + y * this.stride
+}
+
+// Close frees the texture from memory.
+func (this *Texture) Close () error {
+	// i lied we dont actually need to close this, but we will once this
+	// texture resides on the x server or in video memory.
+	return nil
+}
+
+// Clip returns a subset of this texture that points to the same data.
+func (this *Texture) Clip (bounds image.Rectangle) canvas.Texture {
+	clipped := *this
+	clipped.rect = bounds
+	return &clipped
+}
+
+// AssertTexture checks if a given canvas.Texture is a texture from this package.
+func AssertTexture (unknown canvas.Texture) *Texture {
+	if unknown == nil {
+		return nil
+	}
+	if tx, ok := unknown.(*Texture); ok {
+		return tx
+	} else {
+		panic("foregin texture implementation, i did not make this!")
+	}
+}

canvasbox.go

@@ -5,14 +5,14 @@ import "git.tebibyte.media/tomo/tomo/canvas"
 
 type canvasBox struct {
 	*box
+	userDrawer canvas.Drawer
 }
 
 func (backend *Backend) NewCanvasBox () tomo.CanvasBox {
-	box := &canvasBox {
-		box: backend.NewBox().(*box),
-	}
-	box.outer = box
-	return box
+	this    := &canvasBox { }
+	this.box = backend.newBox(this)
+	this.drawer = this
+	return this
 }
 
 func (this *canvasBox) Box () tomo.Box {
@@ -20,10 +20,16 @@ func (this *canvasBox) Box () tomo.Box {
 }
 
 func (this *canvasBox) SetDrawer (drawer canvas.Drawer) {
-	this.drawer = drawer
+	this.userDrawer = drawer
 	this.invalidateDraw()
 }
 
 func (this *canvasBox) Invalidate () {
 	this.invalidateDraw()
 }
+
+func (this *canvasBox) Draw (can canvas.Canvas) {
+	this.box.Draw(can)
+	this.userDrawer.Draw (
+		can.Clip(this.padding.Apply(this.innerClippingBounds)))
+}

containerbox.go

@@ -1,6 +1,7 @@
 package x
 
 import "image"
+import "image/color"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/event"
 import "git.tebibyte.media/tomo/tomo/canvas"
@@ -12,11 +13,11 @@ type containerBox struct {
 	hAlign, vAlign       tomo.Align
 	contentBounds image.Rectangle
 	scroll        image.Point
-	
+	capture [4]bool
+
 	gap             image.Point
 	children        []tomo.Box
 	layout          tomo.Layout
-	propagateEvents bool
 
 	on struct {
 		contentBoundsChange event.FuncBroadcaster
@@ -24,17 +25,21 @@ type containerBox struct {
 }
 
 func (backend *Backend) NewContainerBox() tomo.ContainerBox {
-	box := &containerBox {
-		box:             backend.NewBox().(*box),
-		propagateEvents: true,
-	}
-	box.drawer = box
-	box.outer  = box
-	return box
+	this    := &containerBox { }
+	this.box = backend.newBox(this)
+	return this
 }
 
-func (this *containerBox) Box () tomo.Box {
-	return this
+func (this *containerBox) SetColor (c color.Color) {
+	if this.color == c { return }
+	this.box.SetColor(c)
+	this.invalidateTransparentChildren()
+}
+
+func (this *containerBox) SetTexture (texture canvas.Texture) {
+	if this.texture == texture { return }
+	this.box.SetTexture(texture)
+	this.invalidateTransparentChildren()
 }
 
 func (this *containerBox) SetOverflow (horizontal, vertical bool) {
@@ -56,7 +61,7 @@ func (this *containerBox) ContentBounds () image.Rectangle {
 }
 
 func (this *containerBox) ScrollTo (point image.Point) {
-	// TODO: constrain scroll
+	if this.scroll == point { return }
 	this.scroll = point
 	this.invalidateLayout()
 }
@@ -65,50 +70,67 @@ func (this *containerBox) OnContentBoundsChange (callback func()) event.Cookie {
 	return this.on.contentBoundsChange.Connect(callback)
 }
 
-func (this *containerBox) SetPropagateEvents (propagate bool) {
-	this.propagateEvents = propagate
+func (this *containerBox) CaptureDND (capture bool) {
+	this.capture[eventCategoryDND] = capture
+}
+
+func (this *containerBox) CaptureMouse (capture bool) {
+	this.capture[eventCategoryMouse] = capture
+}
+
+func (this *containerBox) CaptureScroll (capture bool) {
+	this.capture[eventCategoryScroll] = capture
+}
+
+func (this *containerBox) CaptureKeyboard (capture bool) {
+	this.capture[eventCategoryKeyboard] = capture
 }
 
 func (this *containerBox) SetGap (gap image.Point) {
 	if this.gap == gap { return }
 	this.gap = gap
 	this.invalidateLayout()
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 }
 
 func (this *containerBox) Add (child tomo.Object) {
-	box := assertAnyBox(child.Box())
+	box := assertAnyBox(child.GetBox())
 	if indexOf(this.children, tomo.Box(box)) > -1 { return }
-	
+
 	box.setParent(this)
+	box.flushActionQueue()
 	this.children = append(this.children, box)
 	this.invalidateLayout()
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 }
 
 func (this *containerBox) Delete (child tomo.Object) {
-	box := assertAnyBox(child.Box())
+	box := assertAnyBox(child.GetBox())
 	index := indexOf(this.children, tomo.Box(box))
 	if index < 0 { return }
-	
+
 	box.setParent(nil)
 	this.children = remove(this.children, index)
 	this.invalidateLayout()
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 }
 
 func (this *containerBox) Insert (child, before tomo.Object) {
-	box := assertAnyBox(child.Box())
+	box := assertAnyBox(child.GetBox())
 	if indexOf(this.children, tomo.Box(box)) > -1 { return }
 
-	beforeBox := assertAnyBox(before.Box())
+	beforeBox := assertAnyBox(before.GetBox())
 	index     := indexOf(this.children, tomo.Box(beforeBox))
-	if index < 0 { return }
 	
+	if index < 0 {
+		this.children = append(this.children, tomo.Box(box))
+	} else {
+		this.children = insert(this.children, index, tomo.Box(box))
+	}
 	box.setParent(this)
-	this.children = insert(this.children, index, tomo.Box(box))
+
 	this.invalidateLayout()
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 }
 
 func (this *containerBox) Clear () {
@@ -117,7 +139,7 @@ func (this *containerBox) Clear () {
 	}
 	this.children = nil
 	this.invalidateLayout()
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 }
 
 func (this *containerBox) Length () int {
@@ -134,24 +156,59 @@ func (this *containerBox) At (index int) tomo.Object {
 func (this *containerBox) SetLayout (layout tomo.Layout) {
 	this.layout = layout
 	this.invalidateLayout()
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 }
 
 func (this *containerBox) Draw (can canvas.Canvas) {
 	if can == nil { return }
-	this.drawBorders(can)
-	pen := can.Pen()
-	pen.Fill(this.color)
 
 	rocks := make([]image.Rectangle, len(this.children))
 	for index, box := range this.children {
 		rocks[index] = box.Bounds()
 	}
 	for _, tile := range canvas.Shatter(this.bounds, rocks...) {
-		pen.Rectangle(tile)
+		clipped := can.Clip(tile)
+		if this.transparent() && this.parent != nil {
+			this.parent.drawBackgroundPart(clipped)
+		}
+		if clipped == nil { continue }
+		pen := clipped.Pen()
+		pen.Fill(this.color)
+		pen.Texture(this.texture)
+		pen.Rectangle(this.innerClippingBounds)
 	}
 }
 
+func (this *containerBox) drawBackgroundPart (can canvas.Canvas) {
+	if can == nil { return }
+	pen := can.Pen()
+	pen.Fill(this.color)
+	pen.Texture(this.texture)
+
+	if this.transparent() && this.parent != nil {
+		this.parent.drawBackgroundPart(can)
+	}
+	pen.Rectangle(this.innerClippingBounds)
+}
+
+func (this *containerBox) invalidateTransparentChildren () {
+	window := this.window()
+	if window == nil { return }
+	for _, box := range this.children {
+		box := assertAnyBox(box)
+		if box.transparent() {
+			window.invalidateDraw(box)
+		}
+	}
+}
+
+func (this *containerBox) flushActionQueue () {
+	for _, box := range this.children {
+		box.(anyBox).flushActionQueue()
+	}
+	this.box.flushActionQueue()
+}
+
 func (this *containerBox) window () *window {
 	if this.parent == nil { return nil }
 	return this.parent.window()
@@ -162,8 +219,7 @@ func (this *containerBox) canvas () canvas.Canvas {
 }
 
 func (this *containerBox) notifyMinimumSizeChange (child anyBox) {
-	this.recalculateMinimumSize()
-
+	this.invalidateMinimum()
 	size   := child.MinimumSize()
 	bounds := child.Bounds()
 	if bounds.Dx() < size.X || bounds.Dy() < size.Y {
@@ -171,10 +227,14 @@ func (this *containerBox) notifyMinimumSizeChange (child anyBox) {
 	}
 }
 
+func (this *containerBox) boundedLayoutHints () tomo.LayoutHints {
+	hints := this.layoutHints()
+	hints.Bounds = this.ContentBounds().Add(this.InnerBounds().Min)
+	return hints
+}
+
 func (this *containerBox) layoutHints () tomo.LayoutHints {
-	innerBounds := this.InnerBounds().Sub(this.scroll)
 	return tomo.LayoutHints {
-		Bounds:    innerBounds,
 		OverflowX: this.hOverflow,
 		OverflowY: this.vOverflow,
 		AlignX:    this.hAlign,
@@ -183,31 +243,75 @@ func (this *containerBox) layoutHints () tomo.LayoutHints {
 	}
 }
 
-func (this *containerBox) recalculateMinimumSize () {
-	if this.layout == nil {
-		this.SetMinimumSize(image.Point { })
-		return
+func (this *containerBox) contentMinimum () image.Point {
+	minimum := this.box.contentMinimum()
+	if this.layout != nil {
+		layoutMinimum := this.layout.MinimumSize (
+			this.boundedLayoutHints(),
+			this.children)
+		if this.hOverflow { layoutMinimum.X = 0 }
+		if this.vOverflow { layoutMinimum.Y = 0 }
+		minimum = minimum.Add(layoutMinimum)
 	}
-	minimum := this.layout.MinimumSize(this.layoutHints(), this.children)
-	minimum.X += this.padding.Horizontal()
-	minimum.Y += this.padding.Vertical()
-	borderSum := this.borderSum()
-	minimum.X += borderSum.Horizontal()
-	minimum.Y += borderSum.Vertical()
-	this.SetMinimumSize(minimum)
+	return minimum
 }
 
 func (this *containerBox) doLayout () {
 	this.box.doLayout()
 	previousContentBounds := this.contentBounds
+
+	// by default, use innerBounds for contentBounds. if a direction
+	// overflows, use the layout's minimum size for it.
+	var minimum image.Point
 	if this.layout != nil {
-		this.layout.Arrange(this.layoutHints(), this.children)
+		minimum = this.layout.MinimumSize (
+			this.layoutHints(),
+			this.children)
 	}
+	innerBounds := this.InnerBounds()
+	this.contentBounds = innerBounds
+	if this.hOverflow { this.contentBounds.Max.X = this.contentBounds.Min.X + minimum.X }
+	if this.vOverflow { this.contentBounds.Max.Y = this.contentBounds.Min.Y + minimum.Y }
+
+	// offset the content bounds by the scroll so children can be positioned
+	// accordingly.
+	this.constrainScroll()
+	this.contentBounds = this.contentBounds.Add(this.scroll).Sub(innerBounds.Min)
+	
+	// arrange children
+	if this.layout != nil {
+		this.layout.Arrange(this.boundedLayoutHints(), this.children)
+	}
+	
 	if previousContentBounds != this.contentBounds {
 		this.on.contentBoundsChange.Broadcast()
 	}
 }
 
+func (this *containerBox) constrainScroll () {
+	innerBounds := this.InnerBounds()
+	width  := this.contentBounds.Dx()
+	height := this.contentBounds.Dy()
+
+	// X
+	if width <= innerBounds.Dx() {
+		this.scroll.X = 0
+	} else if this.scroll.X > 0 {
+		this.scroll.X = 0
+	} else if this.scroll.X < innerBounds.Dx() - width  {
+		this.scroll.X =  innerBounds.Dx() - width
+	}
+
+	// Y
+	if height <= innerBounds.Dy() {
+		this.scroll.Y = 0
+	} else if this.scroll.Y > 0 {
+		this.scroll.Y = 0
+	} else if this.scroll.Y < innerBounds.Dy() - height {
+		this.scroll.Y = innerBounds.Dy() - height
+	}
+}
+
 func (this *containerBox) recursiveRedo () {
 	this.doLayout()
 	this.doDraw()
@@ -216,15 +320,15 @@ func (this *containerBox) recursiveRedo () {
 	}
 }
 
-func (this *containerBox) boxUnder (point image.Point) anyBox {
-	if this.propagateEvents {
+func (this *containerBox) boxUnder (point image.Point, category eventCategory) anyBox {
+	if !this.capture[category] {
 		for _, box := range this.children {
-			candidate := box.(anyBox).boxUnder(point)
+			candidate := box.(anyBox).boxUnder(point, category)
 			if candidate != nil { return candidate }
 		}
 	}
 
-	return this.box.boxUnder(point)
+	return this.box.boxUnder(point, category)
 }
 
 func (this *containerBox) propagate (callback func (anyBox) bool) bool {
@@ -238,11 +342,15 @@ func (this *containerBox) propagate (callback func (anyBox) bool) bool {
 
 func (this *containerBox) propagateAlt (callback func (anyBox) bool) bool {
 	if !callback(this) { return false}
-	
+
 	for _, box := range this.children {
 		box := box.(anyBox)
 		if !box.propagateAlt(callback) { return false }
 	}
-	
+
 	return true
 }
+
+func (this *containerBox) captures (category eventCategory) bool {
+	return this.capture[category]
+}

event.go

@@ -8,6 +8,31 @@ import "git.tebibyte.media/tomo/xgbkb"
 import "github.com/jezek/xgbutil/xevent"
 import "git.tebibyte.media/tomo/tomo/input"
 
+type scrollSum struct {
+	x, y int
+}
+
+// TODO: this needs to be configurable, we need a config api
+const scrollDistance = 16
+
+func (sum *scrollSum) add (button xproto.Button, window *window, state uint16) {
+	if xgbkb.StateToModifiers(state).Shift {
+		switch button {
+		case 4: sum.x -= scrollDistance
+		case 5: sum.x += scrollDistance
+		case 6: sum.y -= scrollDistance
+		case 7: sum.y += scrollDistance
+		}
+	} else {
+		switch button {
+		case 4: sum.y -= scrollDistance
+		case 5: sum.y += scrollDistance
+		case 6: sum.x -= scrollDistance
+		case 7: sum.x += scrollDistance
+		}
+	}
+}
+
 var buttonCodeTable = map[xproto.Keysym] input.Key {
 	0xFFFFFF: input.KeyNone,
 
@@ -208,7 +233,7 @@ func (window *window) handleKeyPress (
 	} else if key == input.KeyEscape && window.shy {
 		window.Close()
 	} else if window.focused != nil {
-		window.focused.handleKeyDown(key, numberPad)
+		window.keyboardTarget().handleKeyDown(key, numberPad)
 	}
 }
 
@@ -241,7 +266,7 @@ func (window *window) handleKeyRelease (
 	window.updateModifiers(keyEvent.State)
 
 	if window.focused != nil {
-		window.focused.handleKeyUp(key, numberPad)
+		window.keyboardTarget().handleKeyUp(key, numberPad)
 	}
 }
 
@@ -261,20 +286,15 @@ func (window *window) handleButtonPress (
 	if !insideWindow && window.shy && !scrolling {
 		window.Close()
 	} else if scrolling {
-		// TODO
-		// underneath := window.scrollTargetChildAt(point)
-		// if underneath != nil {
-			// if child, ok := underneath.element.(ability.ScrollTarget); ok {
-				// sum := scrollSum { }
-				// sum.add(buttonEvent.Detail, window, buttonEvent.State)
-				// window.compressScrollSum(buttonEvent, &sum)
-				// child.HandleScroll (
-					// point, float64(sum.x), float64(sum.y),
-					// modifiers)
-			// }
-		// }
+		underneath := window.boxUnder(point, eventCategoryScroll)
+		if underneath != nil {
+			sum := scrollSum { }
+			sum.add(buttonEvent.Detail, window, buttonEvent.State)
+			window.compressScrollSum(buttonEvent, &sum)
+			underneath.handleScroll(float64(sum.x), float64(sum.y))
+		}
 	} else {
-		underneath := window.boxUnder(point)
+		underneath := window.boxUnder(point, eventCategoryMouse)
 		window.drags[buttonEvent.Detail] = underneath
 		if underneath != nil {
 			underneath.handleMouseDown(input.Button(buttonEvent.Detail))
@@ -293,6 +313,7 @@ func (window *window) handleButtonRelease (
 	window.updateModifiers(buttonEvent.State)
 	window.updateMousePosition(buttonEvent.EventX, buttonEvent.EventY)
 	dragging := window.drags[buttonEvent.Detail]
+	window.drags[buttonEvent.Detail] = nil
 	
 	if dragging != nil {
 		dragging.handleMouseUp(input.Button(buttonEvent.Detail))
@@ -317,9 +338,14 @@ func (window *window) handleMotionNotify (
 		handled = true
 	}
 
-	if !handled {
-		window.boxUnder(image.Pt(x, y)).handleMouseMove()
+	underneath := window.boxUnder(image.Pt(x, y), eventCategoryMouse)
+	if underneath != nil {
+		window.hover(underneath)
+		if !handled {
+			underneath.handleMouseMove()
+		}
 	}
+	
 }
 
 func (window *window) compressExpose (
@@ -387,6 +413,33 @@ func (window *window) compressConfigureNotify (
 	return
 }
 
+func (window *window) compressScrollSum (
+	firstEvent xproto.ButtonPressEvent,
+	sum *scrollSum,
+) {
+	window.backend.x.Sync()
+	xevent.Read(window.backend.x, false)
+	
+	for index, untypedEvent := range xevent.Peek(window.backend.x) {
+		if untypedEvent.Err != nil { continue }
+		
+		typedEvent, ok := untypedEvent.Event.(xproto.ButtonPressEvent)
+		if !ok { continue }
+
+		if firstEvent.Event == typedEvent.Event &&
+			typedEvent.Detail >= 4 &&
+			typedEvent.Detail <= 7 {
+
+			sum.add(typedEvent.Detail, window, typedEvent.State)
+			defer func (index int) {
+				xevent.DequeueAt(window.backend.x, index)
+			} (index)
+		}
+	}
+
+	return
+}
+
 func (window *window) compressMotionNotify (
 	firstEvent xproto.MotionNotifyEvent,
 ) (

go.mod

@@ -3,13 +3,12 @@ module git.tebibyte.media/tomo/x
 go 1.20
 
 require (
-	git.tebibyte.media/tomo/ggfx v0.4.0
-	git.tebibyte.media/tomo/tomo v0.20.0
-	git.tebibyte.media/tomo/typeset v0.5.2
+	git.tebibyte.media/tomo/tomo v0.31.0
+	git.tebibyte.media/tomo/typeset v0.7.1
 	git.tebibyte.media/tomo/xgbkb v1.0.1
 	github.com/jezek/xgb v1.1.0
 	github.com/jezek/xgbutil v0.0.0-20230603163917-04188eb39cf0
-	golang.org/x/image v0.9.0
+	golang.org/x/image v0.11.0
 )
 
 require (

go.sum

@@ -1,10 +1,8 @@
 git.tebibyte.media/sashakoshka/xgbkb v1.0.0/go.mod h1:pNcE6TRO93vHd6q42SdwLSTTj25L0Yzggz7yLe0JV6Q=
-git.tebibyte.media/tomo/ggfx v0.4.0 h1:3aUHeGS/yYWRV/zCDubBsXnik5ygkMnj/VgrM5Z75A4=
-git.tebibyte.media/tomo/ggfx v0.4.0/go.mod h1:zPoz8BdVQyG2KhEmeGFQBK66V71i6Kj8oVFbrZaCwRA=
-git.tebibyte.media/tomo/tomo v0.20.0 h1:dJJWmCAj/8XtbxjiCkgykP2vNCeP5zuvMEKGChbQ0AI=
-git.tebibyte.media/tomo/tomo v0.20.0/go.mod h1:lTwjpiHbP4UN/kFw+6FwhG600B+PMKVtMOr7wpd5IUY=
-git.tebibyte.media/tomo/typeset v0.5.2 h1:qHxN62/VDnrAouOuzxLmLleQNwAebshrfVYvtoOnAG4=
-git.tebibyte.media/tomo/typeset v0.5.2/go.mod h1:PwDpSdBF3l/EzoIsa2ME7QffVVajnTHZN6l3MHEGe1g=
+git.tebibyte.media/tomo/tomo v0.31.0 h1:LHPpj3AWycochnC8F441aaRNS6Tq6w6WnBrp/LGjyhM=
+git.tebibyte.media/tomo/tomo v0.31.0/go.mod h1:C9EzepS9wjkTJjnZaPBh22YvVPyA4hbBAJVU20Rdmps=
+git.tebibyte.media/tomo/typeset v0.7.1 h1:aZrsHwCG5ZB4f5CruRFsxLv5ezJUCFUFsQJJso2sXQ8=
+git.tebibyte.media/tomo/typeset v0.7.1/go.mod h1:PwDpSdBF3l/EzoIsa2ME7QffVVajnTHZN6l3MHEGe1g=
 git.tebibyte.media/tomo/xgbkb v1.0.1 h1:b3HDUopjdQp1MZrb5Vpil4bOtk3NnNXtfQW27Blw2kE=
 git.tebibyte.media/tomo/xgbkb v1.0.1/go.mod h1:P5Du0yo5hUsojchW08t+Mds0XPIJXwMi733ZfklzjRw=
 github.com/BurntSushi/freetype-go v0.0.0-20160129220410-b763ddbfe298 h1:1qlsVAQJXZHsaM8b6OLVo6muQUQd4CwkH/D3fnnbHXA=
@@ -18,8 +16,8 @@ github.com/jezek/xgbutil v0.0.0-20230603163917-04188eb39cf0/go.mod h1:AHecLyFNy6
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
-golang.org/x/image v0.9.0 h1:QrzfX26snvCM20hIhBwuHI/ThTg18b/+kcKdXHvnR+g=
-golang.org/x/image v0.9.0/go.mod h1:jtrku+n79PfroUbvDdeUWMAI+heR786BofxrbiSF+J0=
+golang.org/x/image v0.11.0 h1:ds2RoQvBvYTiJkwpSFDwCcDFNX7DqjL2WsUgTNk0Ooo=
+golang.org/x/image v0.11.0/go.mod h1:bglhjqbqVuEb9e9+eNR45Jfu7D+T4Qan+NhQk8Ck2P8=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
@@ -42,7 +40,7 @@ golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
-golang.org/x/text v0.11.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
+golang.org/x/text v0.12.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=

system.go

@@ -36,17 +36,25 @@ type parent interface {
 	window                  () *window
 	canvas                  () canvas.Canvas
 	notifyMinimumSizeChange (anyBox)
+	drawBackgroundPart      (canvas.Canvas)
+	captures                (eventCategory) bool
 }
 
 type anyBox interface {
 	tomo.Box
-	doDraw        ()
-	doLayout      ()
-	setParent     (parent)
-	recursiveRedo ()
-	canBeFocused  () bool
-	boxUnder      (image.Point) anyBox
-	recalculateMinimumSize ()
+	canvas.Drawer
+
+	doDraw           ()
+	doLayout         ()
+	doMinimumSize    ()
+	contentMinimum   () image.Point
+	setParent        (parent)
+	getParent        () parent
+	flushActionQueue ()
+	recursiveRedo    ()
+	canBeFocused     () bool
+	boxUnder         (image.Point, eventCategory) anyBox
+	transparent      () bool
 
 	propagate    (func (anyBox) bool) bool
 	propagateAlt (func (anyBox) bool) bool
@@ -56,12 +64,12 @@ type anyBox interface {
 	// handleDndEnter   ()
 	// handleDndLeave   ()
 	// handleDndDrop    (data.Data)
-	// handleMouseEnter ()
-	// handleMouseLeave ()
+	handleMouseEnter ()
+	handleMouseLeave ()
 	handleMouseMove  ()
 	handleMouseDown  (input.Button)
 	handleMouseUp    (input.Button)
-	// handleScroll     (float64, float64)
+	handleScroll     (float64, float64)
 	handleKeyDown    (input.Key, bool)
 	handleKeyUp      (input.Key, bool)
 }
@@ -81,12 +89,13 @@ func (window *window) SetRoot (root tomo.Object) {
 	if root == nil {
 		window.root = nil
 	} else {
-		box := assertAnyBox(root.Box())
+		box := assertAnyBox(root.GetBox())
 		box.setParent(window)
+		box.flushActionQueue()
 		window.invalidateLayout(box)
 		window.root = box
 	}
-	window.recalculateMinimumSize()
+	window.minimumClean = false
 }
 
 func (window *window) window () *window {
@@ -98,7 +107,11 @@ func (window *window) canvas () canvas.Canvas {
 }
 
 func (window *window) notifyMinimumSizeChange (anyBox) {
-	window.recalculateMinimumSize()
+	window.minimumClean = false
+}
+
+func (window *window) invalidateMinimum (box anyBox) {
+	window.needMinimum.Add(box)
 }
 
 func (window *window) invalidateDraw (box anyBox) {
@@ -106,35 +119,72 @@ func (window *window) invalidateDraw (box anyBox) {
 }
 
 func (window *window) invalidateLayout (box anyBox) {
-	// TODO: use a priority queue for this and have the value be the amount
-	// of parents a box has
 	window.needLayout.Add(box)
 	window.invalidateDraw(box)
 }
 
 func (window *window) focus (box anyBox) {
 	if window.focused == box { return }
-	
+
 	previous := window.focused
 	window.focused = box
-	
+
 	if previous != nil {
-		window.invalidateDraw(previous)
 		previous.handleFocusLeave()
 	}
 	if box != nil && box.canBeFocused() {
-		window.invalidateDraw(box)
 		box.handleFocusEnter()
 	}
 }
 
+func (window *window) hover (box anyBox) {
+	if window.hovered == box { return }
+
+	previous := window.hovered
+	window.hovered = box
+
+	if previous != nil {
+		previous.handleMouseLeave()
+	}
+	if box != nil {
+		box.handleMouseEnter()
+	}
+}
+
 func (window *window) anyFocused () bool {
 	return window.focused != nil
 }
 
-func (this *window) boxUnder (point image.Point) anyBox {
+type eventCategory int; const (
+	eventCategoryDND eventCategory = iota
+	eventCategoryMouse
+	eventCategoryScroll
+	eventCategoryKeyboard
+)
+
+func (this *window) boxUnder (point image.Point, category eventCategory) anyBox {
 	if this.root == nil { return nil }
-	return this.root.boxUnder(point)
+	return this.root.boxUnder(point, category)
+}
+
+func (this *window) captures (eventCategory) bool {
+	return false
+}
+
+func (this *window) keyboardTarget () anyBox {
+	focused := this.window().focused
+	if focused == nil { return nil }
+	parent := focused.getParent()
+	for {
+		parentBox, ok := parent.(anyBox)
+		if !ok { break }
+		if parent.captures(eventCategoryKeyboard) {
+			return parentBox
+		}
+		parent = parentBox.getParent()
+	}
+
+	return focused
 }
 
 func (this *window) focusNext () {
@@ -193,7 +243,7 @@ func (window *window) afterEvent () {
 		childBounds = childBounds.Sub(childBounds.Min)
 		window.root.SetBounds(childBounds)
 
-		// full relayout/redraw		
+		// full relayout/redraw
 		if window.root != nil {
 			window.root.recursiveRedo()
 		}
@@ -202,6 +252,12 @@ func (window *window) afterEvent () {
 		return
 	}
 
+	for len(window.needMinimum) > 0 {
+		window.needMinimum.Pop().doMinimumSize()
+	}
+	if !window.minimumClean {
+		window.doMinimumSize()
+	}
 	for len(window.needLayout) > 0 {
 		window.needLayout.Pop().doLayout()
 	}

textbox.go

@@ -13,7 +13,7 @@ import "git.tebibyte.media/tomo/tomo/canvas"
 
 type textBox struct {
 	*box
-	
+
 	hOverflow, vOverflow bool
 	contentBounds image.Rectangle
 	scroll        image.Point
@@ -23,15 +23,16 @@ type textBox struct {
 	face      font.Face
 	wrap      bool
 	hAlign    tomo.Align
+	vAlign    tomo.Align
 
 	selectable  bool
 	selecting   bool
 	selectStart int
 	dot         text.Dot
 	dotColor    color.Color
-	
+
 	drawer typeset.Drawer
-	
+
 	on struct {
 		contentBoundsChange event.FuncBroadcaster
 		dotChange           event.FuncBroadcaster
@@ -39,14 +40,12 @@ type textBox struct {
 }
 
 func (backend *Backend) NewTextBox() tomo.TextBox {
-	box := &textBox {
-		box:       backend.NewBox().(*box),
+	this := &textBox {
 		textColor: color.Black,
 		dotColor:  color.RGBA { B: 255, G: 255, A: 255 },
 	}
-	box.box.drawer = box
-	box.outer  = box
-	return box
+	this.box = backend.newBox(this)
+	return this
 }
 
 func (this *textBox) SetOverflow (horizontal, vertical bool) {
@@ -61,7 +60,7 @@ func (this *textBox) ContentBounds () image.Rectangle {
 }
 
 func (this *textBox) ScrollTo (point image.Point) {
-	// TODO: constrain scroll
+	if this.scroll == point { return }
 	this.scroll = point
 	this.invalidateLayout()
 }
@@ -74,7 +73,7 @@ func (this *textBox) SetText (text string) {
 	if this.text == text { return }
 	this.text = text
 	this.drawer.SetText([]rune(text))
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 	this.invalidateLayout()
 }
 
@@ -88,14 +87,14 @@ func (this *textBox) SetFace (face font.Face) {
 	if this.face == face { return }
 	this.face = face
 	this.drawer.SetFace(face)
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 	this.invalidateLayout()
 }
 
 func (this *textBox) SetWrap (wrap bool) {
 	if this.wrap == wrap { return }
 	this.drawer.SetWrap(wrap)
-	this.recalculateMinimumSize()
+	this.invalidateMinimum()
 	this.invalidateLayout()
 }
 
@@ -117,6 +116,7 @@ func (this *textBox) Select (dot text.Dot) {
 	if this.dot == dot  { return }
 	this.SetFocused(true)
 	this.dot = dot
+	this.scrollToDot()
 	this.on.dotChange.Broadcast()
 	this.invalidateDraw()
 }
@@ -130,16 +130,10 @@ func (this *textBox) OnDotChange (callback func ()) event.Cookie {
 }
 
 func (this *textBox) SetAlign (x, y tomo.Align) {
-	if this.hAlign == x { return }
+	if this.hAlign == x && this.vAlign == y { return }
 	this.hAlign = x
-
-	switch x {
-	case tomo.AlignStart:  this.drawer.SetAlign(typeset.AlignLeft)
-	case tomo.AlignMiddle: this.drawer.SetAlign(typeset.AlignCenter)
-	case tomo.AlignEnd:    this.drawer.SetAlign(typeset.AlignRight)
-	case tomo.AlignEven:   this.drawer.SetAlign(typeset.AlignJustify)
-	}
-	
+	this.vAlign = y
+	this.drawer.SetAlign(typeset.Align(x), typeset.Align(y))
 	this.invalidateDraw()
 }
 
@@ -148,6 +142,11 @@ func (this *textBox) Draw (can canvas.Canvas) {
 	this.drawBorders(can)
 	pen := can.Pen()
 	pen.Fill(this.color)
+	pen.Texture(this.texture)
+	
+	if this.transparent() && this.parent != nil {
+		this.parent.drawBackgroundPart(can)
+	}
 	pen.Rectangle(can.Bounds())
 
 	if this.selectable && this.Focused() {
@@ -167,10 +166,11 @@ func fixPt (point image.Point) fixed.Point26_6 {
 }
 
 func (this *textBox) drawDot (can canvas.Canvas) {
+	if this.face == nil { return }
+
 	pen := can.Pen()
 	pen.Fill(color.Transparent)
 	pen.Stroke(this.textColor)
-	pen.StrokeWeight(1)
 
 	bounds  := this.InnerBounds()
 	metrics := this.face.Metrics()
@@ -180,11 +180,12 @@ func (this *textBox) drawDot (can canvas.Canvas) {
 	height  := this.drawer.LineHeight().Round()
 	ascent  := fixed.Point26_6 { Y: metrics.Descent }
 	descent := fixed.Point26_6 { Y: metrics.Ascent  }
-	
+
 	switch {
 	case dot.Empty():
+		pen.StrokeWeight(1)
 		pen.Path(roundPt(start.Add(ascent)), roundPt(start.Sub(descent)))
-		
+
 	case start.Y == end.Y:
 		pen.Fill(this.dotColor)
 		pen.StrokeWeight(0)
@@ -192,11 +193,11 @@ func (this *textBox) drawDot (can canvas.Canvas) {
 			Min: roundPt(start.Add(ascent)),
 			Max: roundPt(end.Sub(descent)),
 		})
-		
+
 	default:
 		pen.Fill(this.dotColor)
 		pen.StrokeWeight(0)
-		
+
 		rect := image.Rectangle {
 			Min: roundPt(start.Add(ascent)),
 			Max: roundPt(start.Sub(descent)),
@@ -221,7 +222,7 @@ func (this *textBox) drawDot (can canvas.Canvas) {
 
 func (this *textBox) textOffset () image.Point {
 	return this.InnerBounds().Min.
-		Sub(this.scroll).
+		Add(this.scroll).
 		Sub(this.drawer.LayoutBoundsSpace().Min)
 }
 
@@ -269,25 +270,17 @@ func (this *textBox) normalizedLayoutBoundsSpace () image.Rectangle {
 	return bounds.Sub(bounds.Min)
 }
 
-func (this *textBox) recalculateMinimumSize () {
-	minimum := image.Pt (
-		this.drawer.Em().Round(),
-		this.drawer.LineHeight().Round())
+func (this *textBox) contentMinimum () image.Point {
+	minimum := this.drawer.MinimumSize()
 
-	textSize := this.drawer.MinimumSize()
-	if !this.hOverflow && !this.wrap {
-		minimum.X = textSize.X
+	if this.hOverflow || this.wrap {
+		minimum.X = this.drawer.Em().Round()
 	}
-	if !this.vOverflow {
-		 minimum.Y = textSize.Y
+	if this.vOverflow {
+		minimum.Y = this.drawer.LineHeight().Round()
 	}
-	
-	minimum.X += this.padding.Horizontal()
-	minimum.Y += this.padding.Vertical()
-	borderSum := this.borderSum()
-	minimum.X += borderSum.Horizontal()
-	minimum.Y += borderSum.Vertical()
-	this.SetMinimumSize(minimum)
+
+	return minimum.Add(this.box.contentMinimum())
 }
 
 func (this *textBox) doLayout () {
@@ -295,12 +288,63 @@ func (this *textBox) doLayout () {
 	previousContentBounds := this.contentBounds
 
 	innerBounds := this.InnerBounds()
-	this.drawer.SetMaxWidth(innerBounds.Dx())
-	this.drawer.SetMaxHeight(innerBounds.Dy())
-	
-	this.contentBounds = this.normalizedLayoutBoundsSpace().Sub(this.scroll)
-	
+	this.drawer.SetWidth(innerBounds.Dx())
+	this.drawer.SetHeight(innerBounds.Dy())
+
+	this.contentBounds = this.normalizedLayoutBoundsSpace()
+	this.constrainScroll()
+	this.contentBounds = this.contentBounds.Add(this.scroll)
+	// println(this.InnerBounds().String(), this.contentBounds.String())
+
 	if previousContentBounds != this.contentBounds {
 		this.on.contentBoundsChange.Broadcast()
 	}
 }
+
+func (this *textBox) constrainScroll () {
+	innerBounds := this.InnerBounds()
+	width  := this.contentBounds.Dx()
+	height := this.contentBounds.Dy()
+
+	// X
+	if width <= innerBounds.Dx() {
+		this.scroll.X = 0
+	} else if this.scroll.X > 0 {
+		this.scroll.X = 0
+	} else if this.scroll.X < innerBounds.Dx() - width  {
+		this.scroll.X =  innerBounds.Dx() - width
+	}
+
+	// Y
+	if height <= innerBounds.Dy() {
+		this.scroll.Y = 0
+	} else if this.scroll.Y > 0 {
+		this.scroll.Y = 0
+	} else if this.scroll.Y < innerBounds.Dy() - height {
+		this.scroll.Y = innerBounds.Dy() - height
+	}
+}
+
+func (this *textBox) scrollToDot () {
+	dot := roundPt(this.drawer.PositionAt(this.dot.End)).Add(this.textOffset())
+	innerBounds := this.InnerBounds()
+	scroll      := this.scroll
+	em          := this.drawer.Em().Round()
+	lineHeight  := this.drawer.LineHeight().Round()
+
+	// X
+	if dot.X < innerBounds.Min.X + em {
+		scroll.X += innerBounds.Min.X - dot.X + em
+	} else if dot.X > innerBounds.Max.X - em {
+		scroll.X -= dot.X - innerBounds.Max.X + em
+	}
+
+	// Y
+	if dot.Y < innerBounds.Min.Y + lineHeight {
+		scroll.Y += innerBounds.Min.Y - dot.Y + lineHeight
+	} else if dot.Y > innerBounds.Max.Y - lineHeight {
+		scroll.Y -= dot.Y - innerBounds.Max.Y + lineHeight
+	}
+	
+	this.ScrollTo(scroll)
+}

texture.go

@@ -0,0 +1,9 @@
+package x
+
+import "image"
+import "git.tebibyte.media/tomo/x/canvas"
+import "git.tebibyte.media/tomo/tomo/canvas"
+
+func (backend Backend) NewTexture (source image.Image) canvas.TextureCloser {
+	return xcanvas.NewTextureFrom(source)
+}

util.go

@@ -1,5 +1,7 @@
 package x
 
+import "image/color"
+
 func indexOf[T comparable] (haystack []T, needle T) int {
 	for index, test := range haystack {
 		if test == needle {
@@ -18,3 +20,8 @@ func insert[T any] (slice []T, index int, element T) []T {
 	slice[index] = element
 	return slice
 }
+
+func transparent (c color.Color) bool {
+	_, _, _, a := c.RGBA()
+	return a != 0xFFFF
+}

window.go

@@ -8,6 +8,7 @@ import "git.tebibyte.media/tomo/x/canvas"
 import "git.tebibyte.media/tomo/tomo/data"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/tomo/canvas"
 
 import "github.com/jezek/xgb/xproto"
 import "github.com/jezek/xgbutil/ewmh"
@@ -44,10 +45,19 @@ type window struct {
 
 	root    anyBox
 	focused anyBox
+	hovered anyBox
 
-	needDraw   boxSet
-	needLayout boxSet
-	needRedo   bool
+	// TODO: needMinimum and needLayout should be priority queues. for the
+	// minimums, we need to start at the deeper parts of the layout tree and
+	// go upward towards the top. for the layouts, we need to start at the
+	// top of the layout tree and progressively go deeper. this will
+	// eliminate redundant layout calculations.
+
+	needMinimum  boxSet
+	needLayout   boxSet
+	needDraw     boxSet
+	needRedo     bool
+	minimumClean bool
 }
 
 func (backend *Backend) NewWindow (
@@ -63,6 +73,20 @@ func (backend *Backend) NewWindow (
 	return output, err
 }
 
+func (backend *Backend) NewPlainWindow (
+	bounds image.Rectangle,
+) (
+	output tomo.MainWindow,
+	err error,
+) {
+	backend.assert()
+	window, err := backend.newWindow(bounds, false)
+	window.setType("dock")
+	
+	output = mainWindow { window: window }
+	return output, err
+}
+
 func (backend *Backend) newWindow (
 	bounds   image.Rectangle,
 	override bool,
@@ -129,7 +153,7 @@ func (backend *Backend) newWindow (
 		// Connect(backend.x, window.xWindow.Id)
 	
 	window.metrics.bounds = bounds
-	window.setMinimumSize(image.Pt(8, 8))
+	window.doMinimumSize()
 
 	backend.windows[window.xWindow.Id] = window
 
@@ -322,7 +346,7 @@ func (window *window) reallocateCanvas () {
 		if window.xCanvas != nil {
 			window.xCanvas.Destroy()
 		}
-		window.xCanvas = xcanvas.NewFrom(xgraphics.New (
+		window.xCanvas = xcanvas.NewCanvasFrom(xgraphics.New (
 			window.backend.x,
 			image.Rect (
 				0, 0,
@@ -352,15 +376,19 @@ func (window *window) pushRegion (region image.Rectangle) {
 	subCanvas.(*xcanvas.Canvas).Push(window.xWindow.Id)
 }
 
-func (window *window) recalculateMinimumSize () {
-	rootMinimum := image.Point { }
-	if window.root != nil {
-		rootMinimum = window.root.MinimumSize()
-	}
-	window.setMinimumSize(rootMinimum)
+func (window *window) drawBackgroundPart (canvas.Canvas) {
+	// no-op for now? maybe eventually windows will be able to have a
+	// background
 }
 
-func (window *window) setMinimumSize (size image.Point) {
+func (window *window) doMinimumSize () {
+	window.minimumClean = true
+
+	size := image.Point { }
+	if window.root != nil {
+		size = window.root.MinimumSize()
+	}
+	
 	if size.X < 8 { size.X = 8 }
 	if size.Y < 8 { size.Y = 8 }
 	icccm.WmNormalHintsSet (

x/plugin.go

@@ -1,17 +0,0 @@
-// Plugin x provides the X11 backend as a plugin.
-package main
-
-import "git.tebibyte.media/tomo/x"
-import "git.tebibyte.media/tomo/tomo"
-
-func init () {
-	tomo.Register(x.NewBackend)	
-}
-
-func Name () string {
-	return "X"
-}
-
-func Description () string {
-	return "Provides an X11 backend."
-}