Backend unsets style attributes if they are no longer specified

This makes window-level keybinds possible. Exciting!

go.mod

@@ -3,11 +3,8 @@ module git.tebibyte.media/tomo/backend
 go 1.20
 
 require (
-	git.tebibyte.media/tomo/tomo v0.34.0
+	git.tebibyte.media/tomo/tomo v0.45.0
 	git.tebibyte.media/tomo/typeset v0.7.1
-)
-
-require (
 	git.tebibyte.media/tomo/xgbkb v1.0.1
 	github.com/jezek/xgb v1.1.1
 	github.com/jezek/xgbutil v0.0.0-20231116234834-47f30c120111

go.sum

@@ -1,6 +1,6 @@
 git.tebibyte.media/sashakoshka/xgbkb v1.0.0/go.mod h1:pNcE6TRO93vHd6q42SdwLSTTj25L0Yzggz7yLe0JV6Q=
-git.tebibyte.media/tomo/tomo v0.34.0 h1:r5yJPks9rtzdDI2RyAUdqa1qb6BebG0QFe2cTmcFi+0=
-git.tebibyte.media/tomo/tomo v0.34.0/go.mod h1:C9EzepS9wjkTJjnZaPBh22YvVPyA4hbBAJVU20Rdmps=
+git.tebibyte.media/tomo/tomo v0.45.0 h1:fQH0WIPidW275hOq9dE6R7p064xG1RGx2QU68Avlr84=
+git.tebibyte.media/tomo/tomo v0.45.0/go.mod h1:WrtilgKB1y8O2Yu7X4mYcRiqOlPR8NuUnoA/ynkQWrs=
 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=

internal/system/attribute.go

@@ -0,0 +1,70 @@
+package system
+
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/backend/internal/util"
+
+type attrHierarchy [T tomo.Attr] struct {
+	fallback T
+	style    util.Optional[T]
+	user     util.Optional[T]
+}
+
+func (this *attrHierarchy[T]) SetFallback (fallback T) {
+	this.fallback = fallback
+}
+
+func (this *attrHierarchy[T]) SetStyle (style T) (different bool) {
+	styleEquals := false
+	if previous, ok := this.style.Value(); ok {
+		styleEquals = previous.Equals(style)
+	}
+	this.style.Set(style)
+	return !styleEquals && !this.user.Exists()
+}
+
+func (this *attrHierarchy[T]) UnsetStyle () (different bool) {
+	different = this.style.Exists()
+	this.style.Unset()
+	return different
+}
+
+func (this *attrHierarchy[T]) SetUser (user T) (different bool) {
+	userEquals := false
+	if previous, ok := this.user.Value(); ok {
+		userEquals = previous.Equals(user)
+	}
+	this.user.Set(user)
+	return !userEquals
+}
+
+func (this *attrHierarchy[T]) UnsetUser () (different bool) {
+	different = this.user.Exists()
+	this.user.Unset()
+	return different
+}
+
+func (this *attrHierarchy[T]) Set (attr T, user bool) (different bool) {
+	if user {
+		return this.SetUser(attr)
+	} else {
+		return this.SetStyle(attr)
+	}
+}
+
+func (this *attrHierarchy[T]) Unset (user bool) (different bool) {
+	if user {
+		return this.UnsetUser()
+	} else {
+		return this.UnsetStyle()
+	}
+}
+
+func (this *attrHierarchy[T]) Value () T {
+	if user, ok := this.user.Value(); ok {
+		return user
+	} else if style, ok := this.style.Value(); ok{
+		return style
+	} else {
+		return this.fallback
+	}
+}

internal/system/box.go

@@ -9,62 +9,68 @@ import "git.tebibyte.media/tomo/tomo/event"
 import "git.tebibyte.media/tomo/tomo/canvas"
 import "git.tebibyte.media/tomo/backend/internal/util"
 
-type textureMode int; const (
-	textureModeTile textureMode = iota
-	textureModeCenter
-)
-
 type box struct {
 	system *System
 	parent parent
 	outer  anyBox
 
+	tags             util.Set[string]
+	role             tomo.Role
+	lastStyleNonce   int
+	lastIconSetNonce int
+	styleApplicator  *styleApplicator
+
+	minSize             util.Memo[image.Point]
 	bounds              image.Rectangle
-	minSize             image.Point
-	userMinSize         image.Point
 	innerClippingBounds image.Rectangle
 	
-	minSizeQueued bool
-	focusQueued   *bool
+	focusQueued *bool
 
-	padding     tomo.Inset
-	border      []tomo.Border
-	color       color.Color
-	texture     canvas.Texture
-	textureMode textureMode
+	attrColor       attrHierarchy[tomo.AttrColor]
+	attrTexture     attrHierarchy[tomo.AttrTexture]
+	attrTextureMode attrHierarchy[tomo.AttrTextureMode]
+	attrBorder      attrHierarchy[tomo.AttrBorder]
+	attrMinimumSize attrHierarchy[tomo.AttrMinimumSize]
+	attrPadding     attrHierarchy[tomo.AttrPadding]
 
 	dndData   data.Data
 	dndAccept []data.Mime
-	focused   bool
 	focusable bool
 
+	hovered bool
+	focused bool
+	pressed bool
+	
 	canvas util.Memo[canvas.Canvas]
 	drawer canvas.Drawer
 
 	on struct {
-		focusEnter event.FuncBroadcaster
-		focusLeave event.FuncBroadcaster
-		dndEnter   event.FuncBroadcaster
-		dndLeave   event.FuncBroadcaster
-		dndDrop    event.Broadcaster[func (data.Data)]
-		mouseEnter event.FuncBroadcaster
-		mouseLeave event.FuncBroadcaster
-		mouseMove  event.FuncBroadcaster
-		mouseDown  event.Broadcaster[func (input.Button)]
-		mouseUp    event.Broadcaster[func (input.Button)]
-		scroll     event.Broadcaster[func (float64, float64)]
-		keyDown    event.Broadcaster[func (input.Key, bool)]
-		keyUp      event.Broadcaster[func (input.Key, bool)]
+		focusEnter    event.FuncBroadcaster
+		focusLeave    event.FuncBroadcaster
+		dndEnter      event.FuncBroadcaster
+		dndLeave      event.FuncBroadcaster
+		dndDrop       event.Broadcaster[func (data.Data)]
+		mouseEnter    event.FuncBroadcaster
+		mouseLeave    event.FuncBroadcaster
+		mouseMove     event.Broadcaster[func ()                 bool]
+		buttonDown    event.Broadcaster[func (input.Button)     bool]
+		buttonUp      event.Broadcaster[func (input.Button)     bool]
+		scroll        event.Broadcaster[func (float64, float64) bool]
+		keyDown       event.Broadcaster[func (input.Key, bool)  bool]
+		keyUp         event.Broadcaster[func (input.Key, bool)  bool]
+		styleChange   event.FuncBroadcaster
+		iconSetChange event.FuncBroadcaster
 	}
 }
 
 func (this *System) newBox (outer anyBox) *box {
 	box := &box {
 		system:  this,
-		color:   color.Transparent,
 		outer:   outer,
 		drawer:  outer,
+		tags:    make(util.Set[string]),
 	}
+	box.attrColor.SetFallback(tomo.AColor(color.Transparent))
 	box.canvas = util.NewMemo (func () canvas.Canvas {
 		if box.parent == nil { return nil }
 		parentCanvas := box.parent.getCanvas()
@@ -75,15 +81,16 @@ func (this *System) newBox (outer anyBox) *box {
 		box.drawer = box
 		box.outer  = box
 	}
-	box.invalidateMinimum()
+	box.minSize = util.NewMemo(box.calculateMinimumSize)
 	return box
-
 }
 
 func (this *System) NewBox () tomo.Box {
 	return this.newBox(nil)
 }
 
+// ----- public methods ----------------------------------------------------- //
+
 func (this *box) GetBox () tomo.Box {
 	return this.outer
 }
@@ -99,87 +106,43 @@ func (this *box) Bounds () image.Rectangle {
 }
 
 func (this *box) InnerBounds () image.Rectangle {
-	return this.padding.Apply(this.innerClippingBounds)
+	return tomo.Inset(this.attrPadding.Value()).Apply(this.innerClippingBounds)
 }
 
-func (this *box) MinimumSize () image.Point {
-	return this.minSize
+func (this *box) Role () tomo.Role {
+	return this.role
 }
 
-func (this *box) borderSum () tomo.Inset {
-	sum := tomo.Inset { }
-	for _, border := range this.border {
-		sum[0] += border.Width[0]
-		sum[1] += border.Width[1]
-		sum[2] += border.Width[2]
-		sum[3] += border.Width[3]
-	}
-	return sum
+func (this *box) SetRole (role tomo.Role) {
+	if this.role == role { return }
+	this.role = role
+	this.lastStyleNonce = -1
+	this.outer.recursiveReApply()
 }
 
-func (this *box) SetBounds (bounds image.Rectangle) {
-	if this.bounds == bounds { return }
-	this.bounds = bounds
-	this.invalidateLayout()
-}
-
-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) SetTextureTile (texture canvas.Texture) {
-	if this.texture == texture && this.textureMode == textureModeTile { return }
-	this.textureMode = textureModeTile
-	this.texture = texture
-	this.invalidateDraw()
-}
-
-func (this *box) SetTextureCenter (texture canvas.Texture) {
-	if this.texture == texture && this.textureMode == textureModeCenter { return }
-	this.texture = texture
-	this.textureMode = textureModeCenter
-	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) Tag (tag string) bool {
+	switch tag {
+	case "hovered": return this.hovered
+	case "focused": return this.focused
+	case "pressed": return this.pressed
+	default:        return this.tags.Has(tag)
 	}
 }
 
-func (this *box) SetMinimumSize (size image.Point) {
-	if this.userMinSize == size { return }
-	this.userMinSize = size
-	this.invalidateMinimum()
+func (this *box) SetTag (tag string, on bool) {
+	if on {
+		this.tags.Add(tag)
+	} else {
+		delete(this.tags, tag)
+	}
 }
 
-func (this *box) SetPadding (padding tomo.Inset) {
-	if this.padding == padding { return }
-	this.padding = padding
-	this.invalidateLayout()
-	this.invalidateMinimum()
+func (this *box) SetAttr (attr tomo.Attr) {
+	this.outer.setAttr(attr, true)
+}
+
+func (this *box) UnsetAttr (kind tomo.AttrKind) {
+	this.outer.unsetAttr(kind, true)
 }
 
 func (this *box) SetDNDData (dat data.Data) {
@@ -191,7 +154,7 @@ func (this *box) SetDNDAccept (types ...data.Mime) {
 }
 
 func (this *box) SetFocused (focused bool) {
-	hierarchy := this.parent.getHierarchy()
+	hierarchy := this.getHierarchy()
 	if hierarchy == nil {
 		focusedCopy := focused
 		this.focusQueued = &focusedCopy
@@ -206,6 +169,12 @@ func (this *box) SetFocused (focused bool) {
 	}
 }
 
+func (this *box) Focused () bool {
+	hierarchy := this.getHierarchy()
+	if hierarchy == nil { return false }
+	return hierarchy.isFocused(this.outer)
+}
+
 func (this *box) SetFocusable (focusable bool) {
 	if this.focusable == focusable { return }
 	this.focusable = focusable
@@ -214,22 +183,107 @@ func (this *box) SetFocusable (focusable bool) {
 	}
 }
 
-func (this *box) Focused () bool {
-	hierarchy := this.getHierarchy()
-	if hierarchy == nil { return false }
-	return hierarchy.isFocused(this)
+// ----- private methods ---------------------------------------------------- //
+
+func (this *box) setAttr (attr tomo.Attr, user bool) {
+	switch attr := attr.(type) {
+	case tomo.AttrColor:
+		if this.attrColor.Set(attr, user) {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrTexture:
+		if this.attrTexture.Set(attr, user) {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrTextureMode:
+		if this.attrTextureMode.Set(attr, user) {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrBorder:
+		previousBorderSum := this.borderSum()
+		different         := this.attrBorder.Set(attr, user)
+		this.handleBorderChange(previousBorderSum, different)
+		
+	case tomo.AttrMinimumSize:
+		if this.attrMinimumSize.Set(attr, user) {
+			this.invalidateMinimum()
+		}
+		
+	case tomo.AttrPadding:
+		if this.attrPadding.Set(attr, user) {
+			this.invalidateLayout()
+			this.invalidateMinimum()
+		}
+	}
 }
 
-func (this *box) Modifiers () input.Modifiers {
-	hierarchy := this.getHierarchy()
-	if hierarchy == nil { return input.Modifiers { } }
-	return hierarchy.getModifiers()
+func (this *box) unsetAttr (kind tomo.AttrKind, user bool) {
+	switch kind {
+	case tomo.AttrKindColor:
+		if this.attrColor.Unset(user) {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrKindTexture:
+		if this.attrTexture.Unset(user) {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrKindTextureMode:
+		if this.attrTextureMode.Unset(user) {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrKindBorder:
+		previousBorderSum := this.borderSum()
+		different         := this.attrBorder.Unset(user)
+		this.handleBorderChange(previousBorderSum, different)
+	
+	case tomo.AttrKindMinimumSize:
+		if this.attrMinimumSize.Unset(user) {
+			this.invalidateMinimum()
+		}
+		
+	case tomo.AttrKindPadding:
+		if this.attrPadding.Unset(user) {
+			this.invalidateLayout()
+			this.invalidateMinimum()
+		}
+	}
 }
 
-func (this *box) MousePosition () image.Point {
-	hierarchy := this.getHierarchy()
-	if hierarchy == nil { return image.Point { } }
-	return hierarchy.getMousePosition()
+func (this *box) setBounds (bounds image.Rectangle) {
+	if this.bounds == bounds { return }
+	this.bounds = bounds
+	this.invalidateLayout()
+}
+
+func (this *box) minimumSize () image.Point {
+	return this.minSize.Value()
+}
+
+func (this *box) borderSum () tomo.Inset {
+	sum := tomo.Inset { }
+	for _, border := range this.attrBorder.Value() {
+		sum[0] += border.Width[0]
+		sum[1] += border.Width[1]
+		sum[2] += border.Width[2]
+		sum[3] += border.Width[3]
+	}
+	return sum
+}
+
+func (this *box) borderAndPaddingSum () tomo.Inset {
+	sum := this.borderSum()
+	padding := this.attrPadding.Value()
+	sum[0] += padding[0]
+	sum[1] += padding[1]
+	sum[2] += padding[2]
+	sum[3] += padding[3]
+	return sum
 }
 
 // ----- event handler setters ---------------------------------------------- //
@@ -254,70 +308,95 @@ func (this *box) OnMouseEnter (callback func()) event.Cookie {
 func (this *box) OnMouseLeave (callback func()) event.Cookie {
 	return this.on.mouseLeave.Connect(callback)
 }
-func (this *box) OnMouseMove (callback func()) event.Cookie {
+func (this *box) OnMouseMove (callback func() bool) event.Cookie {
 	return this.on.mouseMove.Connect(callback)
 }
-func (this *box) OnMouseDown (callback func(input.Button)) event.Cookie {
-	return this.on.mouseDown.Connect(callback)
+func (this *box) OnButtonDown (callback func(input.Button) bool) event.Cookie {
+	return this.on.buttonDown.Connect(callback)
 }
-func (this *box) OnMouseUp (callback func(input.Button)) event.Cookie {
-	return this.on.mouseUp.Connect(callback)
+func (this *box) OnButtonUp (callback func(input.Button) bool) event.Cookie {
+	return this.on.buttonUp.Connect(callback)
 }
-func (this *box) OnScroll (callback func(deltaX, deltaY float64)) event.Cookie {
+func (this *box) OnScroll (callback func(float64, float64) bool) event.Cookie {
 	return this.on.scroll.Connect(callback)
 }
-func (this *box) OnKeyDown (callback func(key input.Key, numberPad bool)) event.Cookie {
+func (this *box) OnKeyDown (callback func(input.Key, bool) bool) event.Cookie {
 	return this.on.keyDown.Connect(callback)
 }
-func (this *box) OnKeyUp (callback func(key input.Key, numberPad bool)) event.Cookie {
+func (this *box) OnKeyUp (callback func(input.Key, bool) bool) event.Cookie {
 	return this.on.keyUp.Connect(callback)
 }
+func (this *box) OnStyleChange (callback func()) event.Cookie {
+	return this.on.styleChange.Connect(callback)
+}
+func (this *box) OnIconSetChange (callback func()) event.Cookie {
+	return this.on.iconSetChange.Connect(callback)
+}
 func (this *box) handleFocusEnter () {
+	this.focused = true
+	this.invalidateStyle()
 	this.on.focusEnter.Broadcast()
 }
 func (this *box) handleFocusLeave () {
+	this.focused = false
+	this.invalidateStyle()
 	this.on.focusLeave.Broadcast()
 }
 func (this *box) handleMouseEnter () {
+	this.hovered = true
+	this.invalidateStyle()
 	this.on.mouseEnter.Broadcast()
 }
 func (this *box) handleMouseLeave () {
+	this.hovered = false
+	this.invalidateStyle()
 	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 {
-		hierarchy := this.getHierarchy()
-		if hierarchy == nil { return }
-		hierarchy.focus(nil)
-	}
-	for _, listener := range this.on.mouseDown.Listeners() {
-		listener(button)
+func (this *box) handleMouseMove () (caught bool) {
+	for _, listener := range this.on.mouseMove.Listeners() {
+		if listener() { caught = true }
 	}
+	return
 }
-func (this *box) handleMouseUp (button input.Button) {
-	for _, listener := range this.on.mouseUp.Listeners() {
-		listener(button)
+func (this *box) handleMouseDown (button input.Button) (caught bool) {
+	if button == input.ButtonLeft {
+		this.pressed = true
+		this.invalidateStyle()
 	}
+	
+	for _, listener := range this.on.buttonDown.Listeners() {
+		if listener(button) { caught = true }
+	}
+	return
 }
-func (this *box) handleScroll (x, y float64) {
+func (this *box) handleMouseUp (button input.Button) (caught bool) {
+	if button == input.ButtonLeft {
+		this.pressed = false
+		this.invalidateStyle()
+	}
+	
+	for _, listener := range this.on.buttonUp.Listeners() {
+		if listener(button) { caught = true }
+	}
+	return
+}
+func (this *box) handleScroll (x, y float64) (caught bool) {
 	for _, listener := range this.on.scroll.Listeners() {
-		listener(x, y)
+		if listener(x, y) { caught = true }
 	}
+	return
 }
-func (this *box) handleKeyDown (key input.Key, numberPad bool) {
+func (this *box) handleKeyDown (key input.Key, numberPad bool) (caught bool) {
 	for _, listener := range this.on.keyDown.Listeners() {
-		listener(key, numberPad)
+		if listener(key, numberPad) { caught = true }
 	}
+	return
 }
-func (this *box) handleKeyUp (key input.Key, numberPad bool) {
+func (this *box) handleKeyUp (key input.Key, numberPad bool) (caught bool) {
 	for _, listener := range this.on.keyUp.Listeners() {
-		listener(key, numberPad)
+		if listener(key, numberPad) { caught = true }
 	}
+	return
 }
 // -------------------------------------------------------------------------- //
 
@@ -326,34 +405,46 @@ func (this *box) Draw (can canvas.Canvas) {
 	pen := can.Pen()
 	bounds := this.Bounds()
 
+	// get values
+	textureMode := tomo.TextureMode(this.attrTextureMode.Value())
+	texture     := this.attrTexture.Value().Texture
+	col         := this.attrColor.Value().Color
+	if col == nil { col = color.Transparent }
+
 	// background
-	pen.Fill(this.color)
-	if this.textureMode == textureModeTile {
-		pen.Texture(this.texture)
-	}
 	if this.transparent() && this.parent != nil {
 		this.parent.drawBackgroundPart(can)
 	}
+	pen.Fill(col)
+	if textureMode == tomo.TextureModeTile && texture != nil {
+		pen.Texture(texture)
+	}
 	pen.Rectangle(bounds)
 
 	// centered texture
-	if this.textureMode == textureModeCenter && this.texture != nil {
-		textureBounds := this.texture.Bounds()
-		textureOrigin :=
-			bounds.Min.
-			Add(image.Pt (
-				bounds.Dx() / 2,
-				bounds.Dy() / 2)).
-			Sub(image.Pt (
-				textureBounds.Dx() / 2,
-				textureBounds.Dy() / 2))
-	
-		pen.Fill(color.Transparent)
-		pen.Texture(this.texture)
-		pen.Rectangle(textureBounds.Sub(textureBounds.Min).Add(textureOrigin))
+	if textureMode == tomo.TextureModeCenter && texture != nil {
+		this.centeredTexture(can, texture)
 	}
 }
 
+func (this *box) centeredTexture (can canvas.Canvas, texture canvas.Texture) {
+	pen           := can.Pen()
+	bounds        := this.Bounds()
+	textureBounds := texture.Bounds()
+	textureOrigin :=
+		bounds.Min.
+		Add(image.Pt (
+			bounds.Dx() / 2,
+			bounds.Dy() / 2)).
+		Sub(image.Pt (
+			textureBounds.Dx() / 2,
+			textureBounds.Dy() / 2))
+
+	pen.Fill(color.Transparent)
+	pen.Texture(texture)
+	pen.Rectangle(textureBounds.Sub(textureBounds.Min).Add(textureOrigin))
+}
+
 func (this *box) drawBorders (can canvas.Canvas) {
 	if can == nil { return }
 	pen := can.Pen()
@@ -361,6 +452,7 @@ func (this *box) drawBorders (can canvas.Canvas) {
 
 	rectangle := func (x0, y0, x1, y1 int, c color.Color) {
 		area := image.Rect(x0, y0, x1, y1)
+		if area.Empty() { return }
 		if util.Transparent(c) && this.parent != nil {
 			this.parent.drawBackgroundPart(can.SubCanvas(area))
 		}
@@ -368,7 +460,7 @@ func (this *box) drawBorders (can canvas.Canvas) {
 		pen.Rectangle(area)
 	}
 	
-	for _, border := range this.border {
+	for _, border := range this.attrBorder.Value() {
 		rectangle (
 			bounds.Min.X,
 			bounds.Min.Y,
@@ -400,26 +492,26 @@ func (this *box) drawBorders (can canvas.Canvas) {
 
 func (this *box) contentMinimum () image.Point {
 	var minimum image.Point
-	minimum.X += this.padding.Horizontal()
-	minimum.Y += this.padding.Vertical()
+	padding := tomo.Inset(this.attrPadding.Value())
+	minimum.X += padding.Horizontal()
+	minimum.Y += 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
+func (this *box) calculateMinimumSize () image.Point {
+	userMinSize := this.attrMinimumSize.Value()
+	minSize := this.outer.contentMinimum()
+	if minSize.X < userMinSize.X {
+		minSize.X = userMinSize.X
 	}
-	if this.minSize.Y < this.userMinSize.Y {
-		this.minSize.Y = this.userMinSize.Y
+	if minSize.Y < userMinSize.Y {
+		minSize.Y = userMinSize.Y
 	}
 	
-	if this.parent != nil {
-		this.parent.notifyMinimumSizeChange(this)
-	}
+	return minSize
 }
 
 // var drawcnt int
@@ -441,7 +533,11 @@ func (this *box) doLayout () {
 	// laycnt ++
 	
 	this.innerClippingBounds = this.borderSum().Apply(this.bounds)
-	this.loseCanvas()
+	this.outer.recursiveLoseCanvas()
+}
+
+func (this *box) doStyle () {
+	this.styleApplicator.apply(this.outer)
 }
 
 func (this *box) setParent (parent parent) {
@@ -449,6 +545,7 @@ func (this *box) setParent (parent parent) {
 		this.SetFocused(false)
 	}
 	this.parent = parent
+	this.outer.recursiveReApply()
 }
 
 func (this *box) getParent () parent {
@@ -457,10 +554,6 @@ func (this *box) getParent () parent {
 
 func (this *box) flushActionQueue () {
 	if this.getHierarchy() == nil { return }
-
-	if this.minSizeQueued {
-		this.invalidateMinimum()
-	}
 	if this.focusQueued != nil {
 		this.SetFocused(*this.focusQueued)
 	}
@@ -471,8 +564,28 @@ func (this *box) recursiveRedo () {
 	this.doDraw()
 }
 
-func (this *box) loseCanvas () {
-	this.canvas.InvalidateTo(nil)
+func (this *box) recursiveLoseCanvas () {
+	this.canvas.Invalidate()
+}
+
+func (this *box) handleBorderChange (previousBorderSum tomo.Inset, different bool) {
+	// only invalidate the layout if the border is sized differently
+	if this.borderSum() != previousBorderSum {
+		this.invalidateLayout()
+		this.invalidateMinimum()
+	}
+
+	// if the border takes up the same amount of space, only invalidate the
+	// drawing if it looks different
+	if different {
+		this.invalidateDraw()
+	}
+}
+
+func (this *box) invalidateStyle () {
+	hierarchy := this.getHierarchy()
+	if hierarchy == nil { return }
+	hierarchy.invalidateStyle(this.outer)
 }
 
 func (this *box) invalidateLayout () {
@@ -488,11 +601,36 @@ func (this *box) invalidateDraw () {
 }
 
 func (this *box) invalidateMinimum () {
+	this.minSize.Invalidate()
+	if this.parent != nil {
+		this.parent.notifyMinimumSizeChange(this)
+	}
+}
+
+func (this *box) recursiveReApply () {
 	hierarchy := this.getHierarchy()
-	if hierarchy == nil {
-		this.minSizeQueued = true
-	} else {
-		hierarchy.invalidateMinimum(this.outer)
+	if hierarchy == nil { return }
+	
+	// re-apply styling, icons *if needed*
+
+	// style
+	hierarchyStyleNonce := this.getStyleNonce()
+	if this.lastStyleNonce != hierarchyStyleNonce {
+		// i should probably explain why we have a specific style
+		// applicator for every box, it's so style applicators can cache
+		// information about the boxes they're linked to (like all rules
+		// with a matching role).
+		this.lastStyleNonce = hierarchyStyleNonce
+		this.styleApplicator = hierarchy.newStyleApplicator()
+		this.invalidateStyle()
+		this.on.styleChange.Broadcast()
+	}
+
+	// icons
+	hierarchyIconSetNonce := this.getIconSetNonce()
+	if this.lastIconSetNonce != hierarchyIconSetNonce {
+		this.lastIconSetNonce = hierarchyIconSetNonce
+		this.on.iconSetChange.Broadcast()
 	}
 }
 
@@ -500,7 +638,7 @@ func (this *box) canBeFocused () bool {
 	return this.focusable
 }
 
-func (this *box) boxUnder (point image.Point, category eventCategory) anyBox {
+func (this *box) boxUnder (point image.Point) anyBox {
 	if point.In(this.bounds) {
 		return this.outer
 	} else {
@@ -519,7 +657,8 @@ func (this *box) propagateAlt (callback func (anyBox) bool) bool {
 func (this *box) transparent () bool {
 	// TODO uncomment once we have
 	// a way to detect texture transparency
-	return util.Transparent(this.color) /*&&
+	col := this.attrColor.Value().Color
+	return col == nil || util.Transparent(col) /*&&
 		(this.texture == nil || !this.texture.Opaque())*/
 }
 
@@ -533,3 +672,13 @@ func (this *box) getHierarchy () *Hierarchy {
 	if this.parent == nil { return nil }
 	return this.parent.getHierarchy()
 }
+
+func (this *box) getStyleNonce () int {
+	// should panic if not in the tree
+	return this.getHierarchy().getStyleNonce()
+}
+
+func (this *box) getIconSetNonce () int {
+	// should panic if not in the tree
+	return this.getHierarchy().getIconSetNonce()
+}

internal/system/boxquerier.go

@@ -0,0 +1,65 @@
+package system
+
+import "image"
+
+type boxQuerier []anyBox
+
+func (querier boxQuerier) Len () int {
+	return len(querier)
+}
+
+func (querier boxQuerier) MinimumSize (index int) image.Point {
+	if box, ok := querier.box(index); ok {
+		return box.minimumSize()
+	}
+	return image.Point { }
+}
+
+func (querier boxQuerier) RecommendedWidth (index int, height int) int {
+	if box, ok := querier.box(index); ok {
+		if box, ok := box.(anyContentBox); ok {
+			return box.recommendedWidth(height)
+		}
+		return box.minimumSize().X
+	}
+	return 0
+}
+
+func (querier boxQuerier) RecommendedHeight (index int, width int) int {
+	if box, ok := querier.box(index); ok {
+		if box, ok := box.(anyContentBox); ok {
+			return box.recommendedHeight(width)
+		}
+		return box.minimumSize().Y
+	}
+	return 0
+}
+
+func (querier boxQuerier) box (index int) (anyBox, bool) {
+	if index < 0 || index >= len(querier) { return nil, false }
+	return querier[index], true
+}
+
+type boxArranger []anyBox
+
+func (arranger boxArranger) Len () int {
+	return boxQuerier(arranger).Len()
+}
+
+func (arranger boxArranger) MinimumSize (index int) image.Point {
+	return boxQuerier(arranger).MinimumSize(index)
+}
+
+func (arranger boxArranger) RecommendedWidth (index int, height int) int {
+	return boxQuerier(arranger).RecommendedWidth(index, height)
+}
+
+func (arranger boxArranger) RecommendedHeight (index int, width int) int {
+	return boxQuerier(arranger).RecommendedHeight(index, width)
+}
+
+func (arranger boxArranger) SetBounds (index int, bounds image.Rectangle) {
+	if box, ok := boxQuerier(arranger).box(index); ok {
+		box.setBounds(bounds)
+	}
+}

internal/system/canvasbox.go

@@ -15,10 +15,6 @@ func (this *System) NewCanvasBox () tomo.CanvasBox {
 	return box
 }
 
-func (this *canvasBox) Box () tomo.Box {
-	return this
-}
-
 func (this *canvasBox) SetDrawer (drawer canvas.Drawer) {
 	this.userDrawer = drawer
 	this.invalidateDraw()
@@ -29,7 +25,11 @@ func (this *canvasBox) Invalidate () {
 }
 
 func (this *canvasBox) Draw (can canvas.Canvas) {
+	if can == nil { return }
 	this.box.Draw(can)
-	this.userDrawer.Draw (
-		can.SubCanvas(this.padding.Apply(this.innerClippingBounds)))
+	if this.userDrawer != nil {
+		padding := tomo.Inset(this.attrPadding.Value())
+		this.userDrawer.Draw (
+			can.SubCanvas(padding.Apply(this.innerClippingBounds)))
+	}
 }

internal/system/containerbox.go

@@ -10,15 +10,16 @@ import "git.tebibyte.media/tomo/backend/internal/util"
 type containerBox struct {
 	*box
 
-	hOverflow, vOverflow bool
-	hAlign, vAlign       tomo.Align
-	contentBounds        image.Rectangle
-	scroll               image.Point
-	capture              [4]bool
+	contentBounds image.Rectangle
+	scroll        image.Point
+	mask          bool
 
-	gap      image.Point
-	children []tomo.Box
-	layout   tomo.Layout
+	attrGap      attrHierarchy[tomo.AttrGap]
+	attrAlign    attrHierarchy[tomo.AttrAlign]
+	attrOverflow attrHierarchy[tomo.AttrOverflow]
+	attrLayout   attrHierarchy[tomo.AttrLayout]
+
+	children []anyBox
 
 	on struct {
 		contentBoundsChange event.FuncBroadcaster
@@ -31,37 +32,7 @@ func (this *System) NewContainerBox () tomo.ContainerBox {
 	return box
 }
 
-func (this *containerBox) SetColor (c color.Color) {
-	if this.color == c { return }
-	this.box.SetColor(c)
-	this.invalidateTransparentChildren()
-}
-
-func (this *containerBox) SetTextureTile (texture canvas.Texture) {
-	if this.texture == texture { return }
-	this.box.SetTextureTile(texture)
-	this.invalidateTransparentChildren()
-}
-
-func (this *containerBox) SetTextureCenter (texture canvas.Texture) {
-	if this.texture == texture { return }
-	this.box.SetTextureTile(texture)
-	this.invalidateTransparentChildren()
-}
-
-func (this *containerBox) SetOverflow (horizontal, vertical bool) {
-	if this.hOverflow == horizontal && this.vOverflow == vertical { return }
-	this.hOverflow = horizontal
-	this.vOverflow = vertical
-	this.invalidateLayout()
-}
-
-func (this *containerBox) SetAlign (x, y tomo.Align) {
-	if this.hAlign == x && this.vAlign == y { return }
-	this.hAlign = x
-	this.vAlign = y
-	this.invalidateLayout()
-}
+// ----- public methods ----------------------------------------------------- //
 
 func (this *containerBox) ContentBounds () image.Rectangle {
 	return this.contentBounds
@@ -77,32 +48,9 @@ func (this *containerBox) OnContentBoundsChange (callback func()) event.Cookie {
 	return this.on.contentBoundsChange.Connect(callback)
 }
 
-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.invalidateMinimum()
-}
-
 func (this *containerBox) Add (child tomo.Object) {
 	box := assertAnyBox(child.GetBox())
-	if util.IndexOf(this.children, tomo.Box(box)) > -1 { return }
+	if util.IndexOf(this.children, box) > -1 { return }
 
 	box.setParent(this)
 	box.flushActionQueue()
@@ -113,7 +61,7 @@ func (this *containerBox) Add (child tomo.Object) {
 
 func (this *containerBox) Remove (child tomo.Object) {
 	box := assertAnyBox(child.GetBox())
-	index := util.IndexOf(this.children, tomo.Box(box))
+	index := util.IndexOf(this.children, box)
 	if index < 0 { return }
 
 	box.setParent(nil)
@@ -124,15 +72,15 @@ func (this *containerBox) Remove (child tomo.Object) {
 
 func (this *containerBox) Insert (child, before tomo.Object) {
 	box := assertAnyBox(child.GetBox())
-	if util.IndexOf(this.children, tomo.Box(box)) > -1 { return }
+	if util.IndexOf(this.children, box) > -1 { return }
 
 	beforeBox := assertAnyBox(before.GetBox())
-	index     := util.IndexOf(this.children, tomo.Box(beforeBox))
+	index     := util.IndexOf(this.children, beforeBox)
 	
 	if index < 0 {
-		this.children = append(this.children, tomo.Box(box))
+		this.children = append(this.children, box)
 	} else {
-		this.children = util.Insert(this.children, index, tomo.Box(box))
+		this.children = util.Insert(this.children, index, box)
 	}
 	box.setParent(this)
 
@@ -149,7 +97,7 @@ func (this *containerBox) Clear () {
 	this.invalidateMinimum()
 }
 
-func (this *containerBox) Length () int {
+func (this *containerBox) Len () int {
 	return len(this.children)
 }
 
@@ -160,15 +108,20 @@ func (this *containerBox) At (index int) tomo.Object {
 	return this.children[index]
 }
 
-func (this *containerBox) SetLayout (layout tomo.Layout) {
-	this.layout = layout
-	this.invalidateLayout()
-	this.invalidateMinimum()
+func (this *containerBox) SetInputMask (mask bool) {
+	this.mask = mask
 }
 
+// ----- private methods ---------------------------------------------------- //
+
 func (this *containerBox) Draw (can canvas.Canvas) {
 	if can == nil { return }
 	
+	// textureMode := tomo.TextureMode(this.attrTextureMode.Value())
+	texture     := this.attrTexture.Value().Texture
+	col         := this.attrColor.Value().Color
+	if col == nil { col = color.Transparent }
+
 	rocks := make([]image.Rectangle, len(this.children))
 	for index, box := range this.children {
 		rocks[index] = box.Bounds()
@@ -180,17 +133,137 @@ func (this *containerBox) Draw (can canvas.Canvas) {
 		}
 		if clipped == nil { continue }
 		pen := clipped.Pen()
-		pen.Fill(this.color)
-		pen.Texture(this.texture)
+		pen.Fill(col)
+		pen.Texture(texture)
 		pen.Rectangle(this.innerClippingBounds)
 	}
 }
 
+func (this *containerBox) setAttr (attr tomo.Attr, user bool) {
+	switch attr := attr.(type) {
+	case tomo.AttrColor:
+		if this.attrColor.Set(attr, user) {
+			this.invalidateTransparentChildren()
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrTexture:
+		if this.attrTexture.Set(attr, user) {
+			this.invalidateTransparentChildren()
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrTextureMode:
+		if this.attrTextureMode.Set(attr, user) {
+			this.invalidateTransparentChildren()
+			this.invalidateDraw()
+		}
+
+	case tomo.AttrGap:
+		if this.attrGap.Set(attr, user) {
+			this.invalidateLayout()
+			this.invalidateMinimum()
+		}
+		
+	case tomo.AttrAlign:
+		if this.attrAlign.Set(attr, user) {
+			this.invalidateLayout()
+		}
+		
+	case tomo.AttrOverflow:
+		if this.attrOverflow.Set(attr, user) {
+			this.invalidateLayout()
+			this.invalidateMinimum()
+		}
+		
+	case tomo.AttrLayout:
+		if this.attrLayout.Set(attr, user) {
+			this.invalidateLayout()
+			this.invalidateMinimum()
+		}
+
+	default: this.box.setAttr(attr, user)
+	}
+}
+
+func (this *containerBox) unsetAttr (kind tomo.AttrKind, user bool) {
+	switch kind {
+	case tomo.AttrKindColor:
+		if this.attrColor.Unset(user) {
+			this.invalidateTransparentChildren()
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrKindTexture:
+		if this.attrTexture.Unset(user) {
+			this.invalidateTransparentChildren()
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrKindTextureMode:
+		if this.attrTextureMode.Unset(user) {
+			this.invalidateTransparentChildren()
+			this.invalidateDraw()
+		}
+
+	case tomo.AttrKindGap:
+		if this.attrGap.Unset(user) {
+			this.invalidateLayout()
+			this.invalidateMinimum()
+		}
+		
+	case tomo.AttrKindAlign:
+		if this.attrAlign.Unset(user) {
+			this.invalidateLayout()
+		}
+		
+	case tomo.AttrKindOverflow:
+		if this.attrOverflow.Unset(user) {
+			this.invalidateLayout()
+			this.invalidateMinimum()
+		}
+		
+	case tomo.AttrKindLayout:
+		if this.attrLayout.Unset(user) {
+			this.invalidateLayout()
+			this.invalidateMinimum()
+		}
+
+	default: this.box.unsetAttr(kind, user)
+	}
+}
+
+func (this *containerBox) recommendedHeight (width int) int {
+	layout := this.attrLayout.Value().Layout
+	if layout == nil || !this.attrOverflow.Value().Y {
+		return this.minSize.Value().Y
+	} else {
+		return layout.RecommendedHeight(this.layoutHints(), this.boxQuerier(), width) +
+			this.borderAndPaddingSum().Vertical()
+	}
+}
+
+func (this *containerBox) recommendedWidth (height int) int {
+	layout := this.attrLayout.Value().Layout
+	if layout == nil || !this.attrOverflow.Value().X {
+		return this.minSize.Value().X
+	} else {
+		return layout.RecommendedWidth(this.layoutHints(), this.boxQuerier(), height) +
+			this.borderAndPaddingSum().Horizontal()
+	}
+}
+
 func (this *containerBox) drawBackgroundPart (can canvas.Canvas) {
 	if can == nil { return }
 	pen := can.Pen()
-	pen.Fill(this.color)
-	pen.Texture(this.texture)
+	
+	// textureMode := tomo.TextureMode(this.attrTextureMode.Value())
+	texture     := this.attrTexture.Value().Texture
+	col         := this.attrColor.Value().Color
+	if col == nil { col = color.Transparent }
+	
+	pen.Fill(col)
+	pen.Texture(texture)
 
 	if this.transparent() && this.parent != nil {
 		this.parent.drawBackgroundPart(can)
@@ -227,7 +300,7 @@ func (this *containerBox) getCanvas () canvas.Canvas {
 
 func (this *containerBox) notifyMinimumSizeChange (child anyBox) {
 	this.invalidateMinimum()
-	size   := child.MinimumSize()
+	size   := child.minimumSize()
 	bounds := child.Bounds()
 	if bounds.Dx() < size.X || bounds.Dy() < size.Y {
 		this.invalidateLayout()
@@ -235,23 +308,28 @@ func (this *containerBox) notifyMinimumSizeChange (child anyBox) {
 }
 
 func (this *containerBox) layoutHints () tomo.LayoutHints {
+	overflow := this.attrOverflow.Value()
+	align    := this.attrAlign.Value()
+	gap      := image.Point(this.attrGap.Value())
 	return tomo.LayoutHints {
-		OverflowX: this.hOverflow,
-		OverflowY: this.vOverflow,
-		AlignX:    this.hAlign,
-		AlignY:    this.vAlign,
-		Gap:       this.gap,
+		OverflowX: overflow.X,
+		OverflowY: overflow.Y,
+		AlignX:    align.X,
+		AlignY:    align.Y,
+		Gap:       gap,
 	}
 }
 
 func (this *containerBox) contentMinimum () image.Point {
-	minimum := this.box.contentMinimum()
-	if this.layout != nil {
-		layoutMinimum := this.layout.MinimumSize (
+	overflow := this.attrOverflow.Value()
+	minimum  := this.box.contentMinimum()
+	layout := this.attrLayout.Value().Layout
+	if layout != nil {
+		layoutMinimum := layout.MinimumSize (
 			this.layoutHints(),
-			this.children)
-		if this.hOverflow { layoutMinimum.X = 0 }
-		if this.vOverflow { layoutMinimum.Y = 0 }
+			this.boxQuerier())
+		if overflow.X { layoutMinimum.X = 0 }
+		if overflow.Y { layoutMinimum.Y = 0 }
 		minimum = minimum.Add(layoutMinimum)
 	}
 	return minimum
@@ -260,25 +338,27 @@ func (this *containerBox) contentMinimum () image.Point {
 func (this *containerBox) doLayout () {
 	this.box.doLayout()
 	previousContentBounds := this.contentBounds
+	layout := this.attrLayout.Value().Layout
 
 	// by default, use innerBounds (translated to 0, 0) for contentBounds.
 	// if a direction overflows, use the layout's minimum size for it.
 	var minimum image.Point
-	if this.layout != nil {
-		minimum = this.layout.MinimumSize (
+	if layout != nil {
+		minimum = layout.MinimumSize (
 			this.layoutHints(),
-			this.children)
+			this.boxQuerier())
 	}
 	innerBounds := this.InnerBounds()
+	overflow    := this.attrOverflow.Value()
 	this.contentBounds = innerBounds.Sub(innerBounds.Min)
-	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 }
+	if overflow.X { this.contentBounds.Max.X = this.contentBounds.Min.X + minimum.X }
+	if overflow.Y { this.contentBounds.Max.Y = this.contentBounds.Min.Y + minimum.Y }
 	
 	// arrange children
-	if this.layout != nil {
+	if layout != nil {
 		layoutHints := this.layoutHints()
 		layoutHints.Bounds = this.contentBounds
-		this.layout.Arrange(layoutHints, this.children)
+		layout.Arrange(layoutHints, this.boxArranger())
 	}
 
 	// build an accurate contentBounds by unioning the bounds of all child
@@ -294,7 +374,7 @@ func (this *containerBox) doLayout () {
 
 	// offset children and contentBounds by scroll
 	for _, box := range this.children {
-		box.SetBounds(box.Bounds().Add(this.scroll).Add(innerBounds.Min))
+		box.setBounds(box.Bounds().Add(this.scroll).Add(innerBounds.Min))
 	}
 	this.contentBounds = this.contentBounds.Add(this.scroll)
 	
@@ -327,6 +407,14 @@ func (this *containerBox) constrainScroll () {
 	}
 }
 
+func (this *containerBox) boxQuerier () boxQuerier {
+	return boxQuerier(this.children)
+}
+
+func (this *containerBox) boxArranger () boxArranger {
+	return boxArranger(this.children)
+}
+
 func (this *containerBox) recursiveRedo () {
 	this.doLayout()
 	this.doDraw()
@@ -335,12 +423,26 @@ func (this *containerBox) recursiveRedo () {
 	}
 }
 
-func (this *containerBox) boxUnder (point image.Point, category eventCategory) anyBox {
+func (this *containerBox) recursiveLoseCanvas () {
+	this.box.recursiveLoseCanvas()
+	for _, child := range this.children {
+		child.(anyBox).recursiveLoseCanvas()
+	}
+}
+
+func (this *containerBox) recursiveReApply () {
+	this.box.recursiveReApply()
+	for _, child := range this.children {
+		child.(anyBox).recursiveReApply()
+	}
+}
+
+func (this *containerBox) boxUnder (point image.Point) anyBox {
 	if !point.In(this.bounds) { return nil }
 
-	if !this.capture[category] {
+	if !this.mask {
 		for _, box := range this.children {
-			candidate := box.(anyBox).boxUnder(point, category)
+			candidate := box.(anyBox).boxUnder(point)
 			if candidate != nil { return candidate }
 		}
 	}
@@ -368,6 +470,6 @@ func (this *containerBox) propagateAlt (callback func (anyBox) bool) bool {
 	return true
 }
 
-func (this *containerBox) captures (category eventCategory) bool {
-	return this.capture[category]
+func (this *containerBox) masks () bool {
+	return this.mask
 }

internal/system/event.go

@@ -3,6 +3,9 @@ package system
 import "image"
 import "git.tebibyte.media/tomo/tomo/input"
 
+// TODO: once go v1.23 comes out, replace the explicit iterator calls here with
+// range loops
+
 // HandleFocusChange sets whether or not the window containing this Hierarchy
 // has input focus.
 func (this *Hierarchy) HandleFocusChange (focused bool) {
@@ -20,14 +23,31 @@ func (this *Hierarchy) HandleModifiers (modifiers input.Modifiers) {
 // event which triggers this comes with modifier key information,
 // HandleModifiers must be called *before* HandleKeyDown.
 func (this *Hierarchy) HandleKeyDown (key input.Key, numberPad bool) {
-	if key == input.KeyTab && this.modifiers.Alt {
+	caught := false
+	if this.anyFocused() {
+		this.keyboardTargets(func (target anyBox) bool {
+			if target.handleKeyDown(key, numberPad) {
+				caught = true
+				return false
+			}
+			return true
+		})
+	} else {
+		if this.root != nil {
+			caught = this.root.handleKeyDown(key, numberPad)
+		}
+	}
+	if caught { return }
+
+	switch key {
+	case input.KeyTab:
 		if this.modifiers.Shift {
 			this.focusPrevious()
 		} else {
 			this.focusNext()
 		}
-	} else if target := this.keyboardTarget(); target != nil {
-		target.handleKeyDown(key, numberPad)
+	case input.KeyUp:   this.focusPrevious()
+	case input.KeyDown: this.focusNext()
 	}
 }
 
@@ -35,63 +55,88 @@ func (this *Hierarchy) HandleKeyDown (key input.Key, numberPad bool) {
 // which triggers this comes with modifier key information, HandleModifiers must
 // be called *before* HandleKeyUp.
 func (this *Hierarchy) HandleKeyUp (key input.Key, numberPad bool) {
-	if target := this.keyboardTarget(); target != nil {
-		target.handleKeyDown(key, numberPad)
-	}
-}
-
-// HandleMouseDown sends a mouse down event to the Box positioned underneath the
-// mouse cursor and marks it as being "dragged" by that mouse button. If the
-// event which triggers this comes with mouse position information,
-// HandleMouseMove must be called *before* HandleMouseDown.
-func (this *Hierarchy) HandleMouseDown (button input.Button) {
-	underneath := this.boxUnder(this.mousePosition, eventCategoryMouse)
-	this.drags[button] = underneath
-	if underneath != nil {
-		underneath.handleMouseDown(button)
-	}
-}
-
-// HandleMouseUp sends a mouse up event to the Box currently being "dragged" by
-// the specified mouse button, and marks it as being "not dragged" by that mouse
-// button. If the event which triggers this comes with mouse position
-// information, HandleMouseMove must be caleld *before* HandleMouseUp
-func (this *Hierarchy) HandleMouseUp (button input.Button) {
-	dragging := this.drags[button]
-	this.drags[button] = nil
-	if dragging != nil {
-		dragging.handleMouseUp(button)
-	}
-}
-
-// HandleMouseMove sends a mouse move event to any Boxes currently being
-// "dragged" by a mouse button. If none are, it sends the event to the Box which
-// is underneath the mouse pointer.
-func (this *Hierarchy) HandleMouseMove (position image.Point) {
-	if this.mousePosition == position { return }
-	this.mousePosition = position
-
-	handled := false
-	for _, child := range this.drags {
-		if child == nil { continue }
-		child.handleMouseMove()
-		handled = true
-	}
-
-	underneath := this.boxUnder(position, eventCategoryMouse)
-	if underneath != nil {
-		this.hover(underneath)
-		if !handled {
-			underneath.handleMouseMove()
+	if this.anyFocused() {
+		this.keyboardTargets(func (target anyBox) bool {
+			if target.handleKeyUp(key, numberPad) {
+				return false
+			}
+			return true
+		})
+	} else {
+		if this.root != nil {
+			this.root.handleKeyUp(key, numberPad)
 		}
 	}
 }
 
-// HandleScroll sends a scroll event to the Box currently underneath the mouse
-// cursor. 
-func (this *Hierarchy) HandleScroll (x, y float64) {
-	underneath := this.boxUnder(this.mousePosition, eventCategoryScroll)
-	if underneath != nil {
-		underneath.handleScroll(x, y)
+// HandleMouseDown sends a mouse down event to the Boxes positioned underneath
+// the mouse cursor and marks them as being "dragged" by that mouse button,
+// starting at the first Box to mask events and ending at the first box to
+// catch the event. If the event which triggers this comes with mouse position
+// information, HandleMouseMove must be called *before* HandleMouseDown.
+func (this *Hierarchy) HandleMouseDown (button input.Button) {
+	boxes := []anyBox { }
+	first := true
+	this.boxesUnder(this.mousePosition)(func (box anyBox) bool {
+		if first {
+			if box.canBeFocused() {
+				this.focus(box)
+			} else {
+				this.focus(nil)
+			}
+			first = false
+		}
+		boxes = append(boxes, box)
+		return !box.handleMouseDown(button)
+	})
+	this.drags[button] = boxes
+}
+
+// HandleMouseUp sends a mouse up event to the Boxes currently being "dragged"
+// by the specified mouse button, and marks them as being "not dragged" by that
+// mouse button. If the event which triggers this comes with mouse position
+// information, HandleMouseMove must be caleld *before* HandleMouseUp
+func (this *Hierarchy) HandleMouseUp (button input.Button) {
+	for _, box := range this.drags[button] {
+		box.handleMouseUp(button)
+	}
+	this.drags[button] = nil
+}
+
+// HandleMouseMove sends a mouse move event to any Boxes currently being
+// "dragged" by a mouse button. If none are, it sends the event to the Boxes
+// which are underneath the mouse pointer, starting at the first Box to mask
+// events and ending at the first box to catch the event.
+func (this *Hierarchy) HandleMouseMove (position image.Point) {
+	if this.mousePosition == position { return }
+	this.mousePosition = position
+
+	dragged := false
+	for _, dragSet := range this.drags {
+		for _, box := range dragSet {
+			if box.handleMouseMove() { break }
+			dragged = true
+		}
+	}
+	if dragged { return }
+
+	// TODO we can hover over multiple boxes at once. however, any way of
+	// detecting this involves several slice allocations every time we
+	// process a MouseMove event. perhaps we just ought to suck it up and do
+	// it. or perhaps doing *this* is the better way? we may never know.
+	box := this.boxUnder(position)
+	if box != nil {
+		box := this.considerMaskingParents(box)
+		this.hover(box)
+		box.handleMouseMove()
 	}
 }
+
+// HandleScroll sends a scroll event to the Box currently underneath the mouse
+// cursor. If the event which triggers this comes with mouse position
+// information, HandleMouseMove must be called *before* HandleScroll.
+func (this *Hierarchy) HandleScroll (x, y float64) {
+	this.boxesUnder(this.mousePosition)(func (box anyBox) bool {
+		return !box.handleScroll(x, y)
+	})
+}

internal/system/hierarchy.go

@@ -4,6 +4,7 @@ import "image"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/backend/style"
 import "git.tebibyte.media/tomo/backend/internal/util"
 
 // Hierarchy is coupled to a tomo.Window implementation, and manages a tree of
@@ -21,10 +22,10 @@ type Hierarchy struct {
 	
 	modifiers     input.Modifiers
 	mousePosition image.Point
-	drags         [10]anyBox
+	drags         [10][]anyBox
 	minimumSize   image.Point
 
-	needMinimum  util.Set[anyBox]
+	needStyle    util.Set[anyBox]
 	needLayout   util.Set[anyBox]
 	needDraw     util.Set[anyBox]
 	needRedo     bool
@@ -52,10 +53,11 @@ func (this *System) NewHierarchy (link WindowLink) *Hierarchy {
 	hierarchy := &Hierarchy {
 		system:      this,
 		link:        link,
-		needMinimum: make(util.Set[anyBox]),
+		needStyle:   make(util.Set[anyBox]),
 		needLayout:  make(util.Set[anyBox]),
 		needDraw:    make(util.Set[anyBox]),
 	}
+	this.hierarchies.Add(hierarchy)
 	return hierarchy
 }
 
@@ -85,7 +87,7 @@ func (this *Hierarchy) Empty () bool {
 // draw to. The Hierarchy will use the canvas.Canvas's bounds to lay itself out.
 func (this *Hierarchy) SetCanvas (can canvas.Canvas) {
 	this.canvas = can
-	if this.root != nil { this.root.loseCanvas() }
+	if this.root != nil { this.root.recursiveLoseCanvas() }
 	this.needRedo = true
 }
 
@@ -94,6 +96,16 @@ func (this *Hierarchy) MinimumSize () image.Point {
 	return this.minimumSize
 }
 
+// Modifiers returns the current modifier keys being held.
+func (this *Hierarchy) Modifiers () input.Modifiers {
+	return this.modifiers
+}
+
+// MousePosition returns the current mouse position.
+func (this *Hierarchy) MousePosition () image.Point {
+	return this.mousePosition
+}
+
 // AfterEvent should be called at the end of every event cycle.
 func (this *Hierarchy) AfterEvent () {
 	if this.canvas == nil { return }
@@ -103,7 +115,7 @@ func (this *Hierarchy) AfterEvent () {
 		childBounds := this.canvas.Bounds()
 		childBounds = childBounds.Sub(childBounds.Min)
 		if this.root != nil {
-			this.root.SetBounds(childBounds)	
+			this.root.setBounds(childBounds)	
 		}
 
 		// full relayout/redraw
@@ -115,8 +127,8 @@ func (this *Hierarchy) AfterEvent () {
 		return
 	}
 
-	for len(this.needMinimum) > 0 {
-		this.needMinimum.Pop().doMinimumSize()
+	for len(this.needStyle) > 0 {
+		this.needStyle.Pop().doStyle()
 	}
 	if !this.minimumClean {
 		this.doMinimumSize()
@@ -135,6 +147,20 @@ func (this *Hierarchy) AfterEvent () {
 	}
 }
 
+// Close closes the Hierarchy. This should be called when the Window that
+// contains it has been closed.
+func (this *Hierarchy) Close () {
+	this.system.removeHierarchy(this)
+}
+
+func (this *Hierarchy) setStyle () {
+	if this.root != nil { this.root.recursiveReApply() }
+}
+
+func (this *Hierarchy) setIconSet () {
+	if this.root != nil { this.root.recursiveReApply() }
+}
+
 func (this *Hierarchy) getHierarchy () *Hierarchy {
 	return this
 }
@@ -143,6 +169,26 @@ func (this *Hierarchy) getWindow () tomo.Window {
 	return this.link.GetWindow()
 }
 
+func (this *Hierarchy) getStyle () *style.Style {
+	return this.system.style
+}
+
+func (this *Hierarchy) getIconSet () style.IconSet {
+	return this.system.iconSet
+}
+
+func (this *Hierarchy) getFaceSet () style.FaceSet {
+	return this.system.faceSet
+}
+
+func (this *Hierarchy) getStyleNonce () int {
+	return this.system.styleNonce
+}
+
+func (this *Hierarchy) getIconSetNonce () int {
+	return this.system.iconSetNonce
+}
+
 func (this *Hierarchy) getCanvas () canvas.Canvas {
 	return this.canvas
 }
@@ -159,8 +205,8 @@ func (this *Hierarchy) notifyMinimumSizeChange (anyBox) {
 	this.minimumClean = false
 }
 
-func (this *Hierarchy) invalidateMinimum (box anyBox) {
-	this.needMinimum.Add(box)
+func (this *Hierarchy) invalidateStyle (box anyBox) {
+	this.needStyle.Add(box)
 }
 
 func (this *Hierarchy) invalidateDraw (box anyBox) {
@@ -208,38 +254,68 @@ func (this *Hierarchy) anyFocused () bool {
 	return this.focused != nil
 }
 
-func (this *Hierarchy) boxUnder (point image.Point, category eventCategory) anyBox {
-	if this.root == nil { return nil }
-	return this.root.boxUnder(point, category)
-}
-
-func (this *Hierarchy) captures (eventCategory) bool {
+func (this *Hierarchy) masks () bool {
 	return false
 }
 
-func (this *Hierarchy) keyboardTarget () anyBox {
+func (this *Hierarchy) boxUnder (point image.Point) anyBox {
+	if this.root == nil { return nil }
+	return this.root.boxUnder(point)
+}
+
+func (this *Hierarchy) parents (box anyBox) func (func (anyBox) bool) {
+	return func (yield func (anyBox) bool) {
+		for box != nil && yield(box) {
+			parent, ok := box.getParent().(anyBox)
+			if !ok { break }
+			box = parent
+		}
+	}
+}
+
+func (this *Hierarchy) boxesUnder (point image.Point) func (func (anyBox) bool) {
+	return this.parents(this.boxUnder(point))
+}
+
+func (this *Hierarchy) keyboardTargets (yield func (anyBox) bool) {
 	focused := this.focused
-	if focused == nil { return nil }
-	parent := focused.getParent()
+	if focused == nil { return }
+	this.parents(this.considerMaskingParents(focused))(yield)
+}
+
+func (this *Hierarchy) considerMaskingParents (box anyBox) anyBox {
+	parent := box.getParent()
 	for {
 		parentBox, ok := parent.(anyBox)
 		if !ok { break }
-		if parent.captures(eventCategoryKeyboard) {
+		if parent.masks() {
 			return parentBox
 		}
 		parent = parentBox.getParent()
 	}
+	return box
+}
 
-	return focused
+func (this *Hierarchy) isMasked (box anyBox) bool {
+	parent := box.getParent()
+	for {
+		parentBox, ok := parent.(anyBox)
+		if !ok { break }
+		if parent.masks() {
+			return true
+		}
+		parent = parentBox.getParent()
+	}
+	return false
 }
 
 func (this *Hierarchy) focusNext () {
 	found   := !this.anyFocused()
 	focused := false
-	this.propagateAlt (func (box anyBox) bool {
+	this.propagateAlt(func (box anyBox) bool {
 		if found {
 			// looking for the next box to select
-			if box.canBeFocused() {
+			if box.canBeFocused() && !this.isMasked(box) {
 				// found it
 				this.focus(box)
 				focused = true
@@ -260,11 +336,11 @@ func (this *Hierarchy) focusNext () {
 
 func (this *Hierarchy) focusPrevious () {
 	var behind anyBox
-	this.propagate (func (box anyBox) bool {
+	this.propagate(func (box anyBox) bool {
 		if box == this.focused {
 			return false
 		}
-		if box.canBeFocused() { behind = box }
+		if box.canBeFocused() && !this.isMasked(box) { behind = box }
 		return true
 	})
 	this.focus(behind)
@@ -287,13 +363,25 @@ func (this *Hierarchy) drawBackgroundPart (canvas.Canvas) {
 	// if so, windows should be transparent if the color has transparency
 }
 
+// var minimumSizeCount = 0
 func (this *Hierarchy) doMinimumSize () {
 	this.minimumClean = true
+	// println("doMinimumSize", minimumSizeCount)
+	// minimumSizeCount ++
 
+	previousMinimumSize := this.minimumSize
 	this.minimumSize = image.Point { }
 	if this.root != nil {
-		this.minimumSize = this.root.MinimumSize()
+		this.minimumSize = this.root.minimumSize()
 	}
 
-	this.link.NotifyMinimumSizeChange()
+	if previousMinimumSize != this.minimumSize {
+		this.link.NotifyMinimumSizeChange()
+	}
+}
+
+func (this *Hierarchy) newStyleApplicator () *styleApplicator {
+	return &styleApplicator {
+		style: this.getStyle(),
+	}
 }

internal/system/internal-iface.go

@@ -5,14 +5,6 @@ import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/canvas"
 
-// eventCategory lists kinds of Tomo events.
-type eventCategory int; const (
-	eventCategoryDND eventCategory = iota
-	eventCategoryMouse
-	eventCategoryScroll
-	eventCategoryKeyboard
-)
-
 // parent is any hierarchical type which contains other boxes. This can be a
 // Hierarchy, containerBox, etc.
 type parent interface {
@@ -27,9 +19,8 @@ type parent interface {
 	// given Canvas, filling the Canvas's entire bounds. The origin (0, 0)
 	// of the given Canvas is assumed to be the same as the parent's canvas.
 	drawBackgroundPart      (canvas.Canvas)
-	// captures returns whether or not this parent captures the given event
-	// category.
-	captures                (eventCategory) bool
+	// catches returns whether or not this parent masks events.
+	masks                   () bool
 }
 
 // anyBox is any tomo.Box type that is implemented by this package.
@@ -44,21 +35,27 @@ type anyBox interface {
 	
 	// doDraw re-paints the anyBox onto its currently held Canvas non-recursively
 	// doLayout re-calculates the layout of the anyBox non-recursively
-	// doMinimumSize re-calculates the minimum size of the anyBox non-recursively
-	doDraw        ()
-	doLayout      ()
-	doMinimumSize ()
+	// doStyle re-applies the box's style non-recursively
+	doDraw   ()
+	doLayout ()
+	doStyle  ()
 
 	// flushActionQueue performs any queued actions, like invalidating the
 	// minimum size or grabbing input focus.
-	flushActionQueue ()
+	flushActionQueue    ()
 	// recursiveRedo recursively recalculates the minimum size, layout, and
 	// re-paints this anyBox and all of its children.
-	recursiveRedo    ()
+	recursiveRedo       ()
 	// loseCanvas causes this anyBox and its children (if applicable) to
 	// lose their canvases and re-cut them as needed.
-	loseCanvas       ()
+	recursiveLoseCanvas ()
+	// recursiveReAppply causes this anyBox and its children (if applicable)
+	// to check whether they have an outdated style or icon set, and if so,
+	// update it and trigger the appropriate event broadcasters.
+	recursiveReApply    ()
 
+	// minimumSize returns the box's minimum size
+	minimumSize      () image.Point
 	// contentMinimum returns the minimum dimensions of this box's content
 	contentMinimum   () image.Point
 	// canBeFocused returns whether or not this anyBox is capable of holding
@@ -67,12 +64,21 @@ type anyBox interface {
 	// boxUnder returns the anyBox under the mouse pointer. It can be this
 	// anyBox, one of its children (if applicable). It must return nil if
 	// the mouse pointer is outside of this anyBox's bounds.
-	boxUnder         (image.Point, eventCategory) anyBox
+	boxUnder         (image.Point) anyBox
 	// transparent returns whether or not this anyBox contains transparent
 	// pixels or not, and thus needs its parent's backround to be painted
 	// underneath it.
 	transparent      () bool
 
+	// setBounds sets the box's bounds.
+	setBounds (image.Rectangle)
+	// setAttr sets an attribute at the user or style level depending
+	// on the value of user.
+	setAttr   (attr tomo.Attr, user bool)
+	// unsetAttr unsets an attribute at the user or style level depending
+	// on the value of user.
+	unsetAttr (kind tomo.AttrKind, user bool)
+
 	// propagate recursively calls a function on this anyBox, and all of its
 	// children (if applicable) The normal propagate behavior calls the
 	// callback on all children before calling it on this anyBox, and
@@ -81,19 +87,28 @@ type anyBox interface {
 	propagate    (func (anyBox) bool) bool
 	propagateAlt (func (anyBox) bool) bool
 
-	handleFocusEnter ()
-	handleFocusLeave ()
-	// handleDndEnter   ()
-	// handleDndLeave   ()
-	// handleDndDrop    (data.Data)
-	handleMouseEnter ()
-	handleMouseLeave ()
-	handleMouseMove  ()
-	handleMouseDown  (input.Button)
-	handleMouseUp    (input.Button)
-	handleScroll     (float64, float64)
-	handleKeyDown    (input.Key, bool)
-	handleKeyUp      (input.Key, bool)
+	handleFocusEnter  ()
+	handleFocusLeave  ()
+	// handleDndEnter    ()
+	// handleDndLeave    ()
+	// handleDndDrop     (data.Data)
+	handleMouseEnter  ()
+	handleMouseLeave  ()
+	handleMouseMove   ()                 bool
+	handleMouseDown   (input.Button)     bool
+	handleMouseUp     (input.Button)     bool
+	handleScroll      (float64, float64) bool
+	handleKeyDown     (input.Key, bool)  bool
+	handleKeyUp       (input.Key, bool)  bool
+}
+
+type anyContentBox interface {
+	anyBox
+
+	// recommendedWidth returns the recommended width for a given height.
+	recommendedWidth (int) int
+	// recommendedHeight returns the recommended height for a given height.
+	recommendedHeight (int) int
 }
 
 func assertAnyBox (unknown tomo.Box) anyBox {

internal/system/style.go

@@ -0,0 +1,60 @@
+package system
+
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/backend/style"
+
+type styleApplicator struct {
+	style      *style.Style
+	role       tomo.Role
+	rules      []style.Rule
+	currentSet style.AttrSet
+}
+
+func (this *styleApplicator) apply (box anyBox) {
+	if box.Role() != this.role {
+		this.role = box.Role()
+		// the role has changed, so re-cache the list of rules
+		this.rules = nil
+		for _, rule := range this.style.Rules {
+			role := box.Role()
+			// blank fields match anything
+			if rule.Role.Package == "" { role.Package = "" }
+			if rule.Role.Object  == "" { role.Object  = "" }
+			if rule.Role == role {
+				this.rules = append(this.rules, rule)
+			}
+		}
+	}
+
+	// compile list of attributes by searching through the cached ruleset
+	attrs := make(style.AttrSet)
+	for _, rule := range this.rules {
+		satisifed := true
+		for _, tag := range rule.Tags {
+			if !box.Tag(tag) {
+				satisifed = false
+				break
+			}
+		}
+
+		if satisifed {
+			attrs.MergeOver(rule.Set)
+		}
+	}
+
+	// reset an attribute if it is no longer specified
+	if this.currentSet != nil {
+		for kind := range this.currentSet {
+			_, exists := attrs[kind]
+			if !exists {
+				box.unsetAttr(kind, false)
+			}
+		}
+	}
+
+	// apply that list of attributes
+	this.currentSet = attrs
+	for _, attr := range attrs {
+		box.setAttr(attr, false)
+	}
+}

internal/system/system.go

@@ -3,11 +3,21 @@ package system
 import "io"
 import "image"
 import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/backend/style"
+import "git.tebibyte.media/tomo/backend/internal/util"
 
 // System is coupled to a tomo.Backend implementation, and manages Hierarchies
 // and Boxes.
 type System struct {
 	link BackendLink
+
+	style        *style.Style
+	iconSet      style.IconSet
+	faceSet      style.FaceSet
+	styleNonce   int
+	iconSetNonce int
+	
+	hierarchies util.Set[*Hierarchy]
 }
 
 // BackendLink allows the System to call up into the tomo.Backend implementation
@@ -15,8 +25,6 @@ type System struct {
 type BackendLink interface {
 	// NewTexture creates a new texture from an image.
 	NewTexture (image.Image) canvas.TextureCloser
-	// NewCanvas creates a new blank canvas with the specified bounds.
-	NewCanvas  (image.Rectangle) canvas.Canvas
 	// NewSurface creates a new surface with the specified bounds.
 	NewSurface (image.Rectangle) (SurfaceLink, error)
 }
@@ -32,6 +40,36 @@ type SurfaceLink interface {
 // New creates a new System.
 func New (link BackendLink) *System {
 	return &System {
-		link: link,
+		link:        link,
+		hierarchies: make(util.Set[*Hierarchy]),
 	}
 }
+
+// SetStyle sets the style that is applied to objects, and notifies them
+// that the style has changed.
+func (this *System) SetStyle (style *style.Style) {
+	this.style = style
+	this.styleNonce ++
+	for hierarchy := range this.hierarchies {
+		hierarchy.setStyle()
+	}
+}
+
+// SetIconSet sets the icon set that provides icon textures, and notifies
+// objects that the icons have changed.
+func (this *System) SetIconSet (iconSet style.IconSet) {
+	this.iconSet = iconSet
+	this.iconSetNonce ++
+	for hierarchy := range this.hierarchies {
+		hierarchy.setIconSet()
+	}
+}
+
+// SetFaceSet sets the face set that provides font faces.
+func (this *System) SetFaceSet (faceSet style.FaceSet) {
+	this.faceSet = faceSet
+}
+
+func (this *System) removeHierarchy (hierarchy *Hierarchy) {
+	delete(this.hierarchies, hierarchy)
+}

internal/system/textbox.go

@@ -10,28 +10,30 @@ import "git.tebibyte.media/tomo/tomo/text"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/event"
 import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/backend/internal/util"
 
 type textBox struct {
 	*box
 
-	hOverflow, vOverflow bool
 	contentBounds image.Rectangle
 	scroll        image.Point
 
-	text      string
-	textColor color.Color
-	face      font.Face
-	wrap      bool
-	hAlign    tomo.Align
-	vAlign    tomo.Align
+	attrTextColor attrHierarchy[tomo.AttrTextColor]
+	attrDotColor  attrHierarchy[tomo.AttrDotColor]
+	attrFace      attrHierarchy[tomo.AttrFace]
+	attrWrap      attrHierarchy[tomo.AttrWrap]
+	attrAlign     attrHierarchy[tomo.AttrAlign]
+	attrOverflow  attrHierarchy[tomo.AttrOverflow]
 
+	text        string
+	runes       []rune
 	selectable  bool
 	selecting   bool
 	selectStart int
 	dot         text.Dot
-	dotColor    color.Color
 
 	drawer typeset.Drawer
+	face   util.Cycler[font.Face]
 
 	on struct {
 		contentBoundsChange event.FuncBroadcaster
@@ -40,20 +42,14 @@ type textBox struct {
 }
 
 func (this *System) NewTextBox () tomo.TextBox {
-	box := &textBox {
-		textColor: color.Black,
-		dotColor:  color.RGBA { B: 255, G: 255, A: 255 },
-	}
+	box := &textBox { }
 	box.box = this.newBox(box)
+	box.attrTextColor.SetFallback(tomo.ATextColor(color.Black))
+	box.attrDotColor.SetFallback(tomo.ADotColor(color.RGBA { G: 255, B: 255, A: 255}))
 	return box
 }
 
-func (this *textBox) SetOverflow (horizontal, vertical bool) {
-	if this.hOverflow == horizontal && this.vOverflow == vertical { return }
-	this.hOverflow = horizontal
-	this.vOverflow = vertical
-	this.invalidateLayout()
-}
+// ----- public methods ----------------------------------------------------- //
 
 func (this *textBox) ContentBounds () image.Rectangle {
 	return this.contentBounds
@@ -65,35 +61,24 @@ func (this *textBox) ScrollTo (point image.Point) {
 	this.invalidateLayout()
 }
 
+func (this *textBox) RecommendedHeight (width int) int {
+	return this.drawer.ReccomendedHeightFor(width) + this.borderAndPaddingSum().Vertical()
+}
+
+func (this *textBox) RecommendedWidth (height int) int {
+	// TODO maybe not the best idea?
+	return this.minimumSize().X
+}
+
 func (this *textBox) OnContentBoundsChange (callback func()) event.Cookie {
 	return this.on.contentBoundsChange.Connect(callback)
 }
 
 func (this *textBox) SetText (text string) {
 	if this.text == text { return }
-	this.text = text
-	this.drawer.SetText([]rune(text))
-	this.invalidateMinimum()
-	this.invalidateLayout()
-}
-
-func (this *textBox) SetTextColor (c color.Color) {
-	if this.textColor == c { return }
-	this.textColor = c
-	this.invalidateDraw()
-}
-
-func (this *textBox) SetFace (face font.Face) {
-	if this.face == face { return }
-	this.face = face
-	this.drawer.SetFace(face)
-	this.invalidateMinimum()
-	this.invalidateLayout()
-}
-
-func (this *textBox) SetWrap (wrap bool) {
-	if this.wrap == wrap { return }
-	this.drawer.SetWrap(wrap)
+	this.text  = text
+	this.runes = []rune(text)
+	this.drawer.SetText(this.runes)
 	this.invalidateMinimum()
 	this.invalidateLayout()
 }
@@ -103,14 +88,6 @@ func (this *textBox) SetSelectable (selectable bool) {
 	this.selectable = selectable
 }
 
-func (this *textBox) SetDotColor (c color.Color) {
-	if this.dotColor == c { return }
-	this.dotColor = c
-	if !this.dot.Empty() {
-		this.invalidateDraw()
-	}
-}
-
 func (this *textBox) Select (dot text.Dot) {
 	if !this.selectable { return }
 	if this.dot == dot  { return }
@@ -129,21 +106,19 @@ func (this *textBox) OnDotChange (callback func ()) event.Cookie {
 	return this.on.dotChange.Connect(callback)
 }
 
-func (this *textBox) SetAlign (x, y tomo.Align) {
-	if this.hAlign == x && this.vAlign == y { return }
-	this.hAlign = x
-	this.vAlign = y
-	this.drawer.SetAlign(typeset.Align(x), typeset.Align(y))
-	this.invalidateDraw()
-}
+// ----- private methods ---------------------------------------------------- //
 
 func (this *textBox) Draw (can canvas.Canvas) {
 	if can == nil { return }
-	this.drawBorders(can)
-	pen := can.Pen()
-	pen.Fill(this.color)
-	pen.Texture(this.texture)
 
+	texture := this.attrTexture.Value().Texture
+	col     := this.attrColor.Value().Color
+	
+	this.drawBorders(can)
+	
+	pen := can.Pen()
+	pen.Fill(col)
+	pen.Texture(texture)
 	if this.transparent() && this.parent != nil {
 		this.parent.drawBackgroundPart(can)
 	}
@@ -153,8 +128,96 @@ func (this *textBox) Draw (can canvas.Canvas) {
 		this.drawDot(can)
 	}
 
-	if this.face == nil { return }
-	this.drawer.Draw(can, this.textColor, this.textOffset())
+	if this.face.Value() != nil {
+		textColor := this.attrTextColor.Value().Color
+		this.drawer.Draw(can, textColor, this.textOffset())
+	}
+}
+
+func (this *textBox) setAttr (attr tomo.Attr, user bool) {
+	switch attr := attr.(type) {
+	case tomo.AttrTextColor:
+		if this.attrTextColor.Set(attr, user) && !this.dot.Empty() {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrDotColor:
+		if this.attrDotColor.Set(attr, user) && !this.dot.Empty() {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrFace:
+		if this.attrFace.Set(attr, user) {
+			this.handleFaceChange()
+		}
+		
+	case tomo.AttrWrap:
+		if this.attrWrap.Set(attr, user) {
+			this.drawer.SetWrap(bool(this.attrWrap.Value()))
+			this.invalidateMinimum()
+			this.invalidateLayout()
+		}
+		
+	case tomo.AttrAlign:
+		if this.attrAlign.Set(attr, user) {
+			align := this.attrAlign.Value()
+			this.drawer.SetAlign (
+				typeset.Align(align.X),
+				typeset.Align(align.Y))
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrOverflow:
+		if this.attrOverflow.Set(attr, user) {
+			this.invalidateMinimum()
+			this.invalidateLayout()
+		}
+		
+	default: this.box.setAttr(attr, user)
+	}
+}
+
+func (this *textBox) unsetAttr (kind tomo.AttrKind, user bool) {
+	switch kind {
+	case tomo.AttrKindTextColor:
+		if this.attrTextColor.Unset(user) && !this.dot.Empty() {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrKindDotColor:
+		if this.attrDotColor.Unset(user) && !this.dot.Empty() {
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrKindFace:
+		if this.attrFace.Unset(user) {
+			this.handleFaceChange()
+		}
+		
+	case tomo.AttrKindWrap:
+		if this.attrWrap.Unset(user) {
+			this.drawer.SetWrap(bool(this.attrWrap.Value()))
+			this.invalidateMinimum()
+			this.invalidateLayout()
+		}
+		
+	case tomo.AttrKindAlign:
+		if this.attrAlign.Unset(user) {
+			align := this.attrAlign.Value()
+			this.drawer.SetAlign (
+				typeset.Align(align.X),
+				typeset.Align(align.Y))
+			this.invalidateDraw()
+		}
+		
+	case tomo.AttrKindOverflow:
+		if this.attrOverflow.Unset(user) {
+			this.invalidateMinimum()
+			this.invalidateLayout()
+		}
+		
+	default: this.box.unsetAttr(kind, user)
+	}
 }
 
 func roundPt (point fixed.Point26_6) image.Point {
@@ -166,14 +229,16 @@ func fixPt (point image.Point) fixed.Point26_6 {
 }
 
 func (this *textBox) drawDot (can canvas.Canvas) {
-	if this.face == nil { return }
+	face := this.face.Value()
+	if face == nil { return }
+
+	textColor := this.attrTextColor.Value().Color
+	dotColor  := this.attrDotColor.Value().Color
 	
 	pen := can.Pen()
-	pen.Fill(color.Transparent)
-	pen.Stroke(this.textColor)
 
 	bounds  := this.InnerBounds()
-	metrics := this.face.Metrics()
+	metrics := face.Metrics()
 	dot     := this.dot.Canon()
 	start   := this.drawer.PositionAt(dot.Start).Add(fixPt(this.textOffset()))
 	end     := this.drawer.PositionAt(dot.End  ).Add(fixPt(this.textOffset()))
@@ -183,11 +248,12 @@ func (this *textBox) drawDot (can canvas.Canvas) {
 
 	switch {
 	case dot.Empty():
+		pen.Stroke(textColor)
 		pen.StrokeWeight(1)
 		pen.Path(roundPt(start.Add(ascent)), roundPt(start.Sub(descent)))
 
 	case start.Y == end.Y:
-		pen.Fill(this.dotColor)
+		pen.Fill(dotColor)
 		pen.StrokeWeight(0)
 		pen.Rectangle(image.Rectangle {
 			Min: roundPt(start.Add(ascent)),
@@ -195,7 +261,7 @@ func (this *textBox) drawDot (can canvas.Canvas) {
 		})
 
 	default:
-		pen.Fill(this.dotColor)
+		pen.Fill(dotColor)
 		pen.StrokeWeight(0)
 
 		rect := image.Rectangle {
@@ -226,44 +292,121 @@ func (this *textBox) textOffset () image.Point {
 		Sub(this.drawer.LayoutBoundsSpace().Min)
 }
 
+func (this *textBox) handleFocusEnter () {
+	this.invalidateDraw()
+	this.box.handleFocusEnter()
+}
+
 func (this *textBox) handleFocusLeave () {
-	this.on.dotChange.Broadcast()
 	this.invalidateDraw()
 	this.box.handleFocusLeave()
 }
 
-func (this *textBox) handleMouseDown (button input.Button) {
-	if button == input.ButtonLeft {
+func (this *textBox) handleMouseDown (button input.Button) bool {
+	if this.mouseButtonCanDrag(button) {
 		index           := this.runeUnderMouse()
 		this.selectStart = index
 		this.selecting   = true
 		this.Select(text.Dot { Start: this.selectStart, End: index })
 	}
-	this.box.handleMouseDown(button)
+	return this.box.handleMouseDown(button)
 }
 
-func (this *textBox) handleMouseUp (button input.Button) {
-	if button == input.ButtonLeft && this.selecting {
+func (this *textBox) handleMouseUp (button input.Button) bool {
+	if this.mouseButtonCanDrag(button) && this.selecting {
 		index         := this.runeUnderMouse()
 		this.selecting = false
 		this.Select(text.Dot { Start: this.selectStart, End: index })
 	}
-	this.box.handleMouseUp(button)
+	return this.box.handleMouseUp(button)
 }
 
-func (this *textBox) handleMouseMove () {
+func (this *textBox) mouseButtonCanDrag (button input.Button) bool {
+	 return button == input.ButtonLeft   ||
+	 	button == input.ButtonMiddle ||
+	 	button == input.ButtonRight
+}
+
+func (this *textBox) handleMouseMove () bool {
 	if this.selecting {
 		index := this.runeUnderMouse()
 		this.Select(text.Dot { Start: this.selectStart, End: index })
 	}
-	this.box.handleMouseMove()
+	return this.box.handleMouseMove()
 }
 
 func (this *textBox) runeUnderMouse () int {
-	position := this.MousePosition().Sub(this.textOffset())
+	window := this.Window()
+	if window == nil { return 0 }
+	position := window.MousePosition().Sub(this.textOffset())
 	return this.drawer.AtPosition(fixPt(position))
 }
 
+func (this *textBox) handleKeyDown (key input.Key, numberPad bool) bool {
+	if this.box.handleKeyDown(key, numberPad) { return true  }
+	if !this.selectable                       { return false }
+
+	// because fuck you thats why!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+	modifiers := this.Window().Modifiers()
+	dot       := this.Dot()
+	sel       := modifiers.Shift
+	word      := modifiers.Control
+	switch {
+	case key == input.KeyHome || (modifiers.Alt && key == input.KeyLeft):
+		dot.End = 0
+		if !sel { dot.Start = dot.End }
+		this.Select(dot)
+		return true
+	case key == input.KeyEnd || (modifiers.Alt && key == input.KeyRight):
+		dot.End = len(this.text)
+		if !sel { dot.Start = dot.End }
+		this.Select(dot)
+		return true
+	case key == input.KeyLeft:
+		if sel {
+			this.Select(text.SelectLeft(this.runes, dot, word))
+		} else {
+			this.Select(text.MoveLeft(this.runes, dot, word))
+		}
+		return true
+	case key == input.KeyRight:
+		if sel {
+			this.Select(text.SelectRight(this.runes, dot, word))
+		} else {
+			this.Select(text.MoveRight(this.runes, dot, word))
+		}
+		return true
+	case key == input.Key('a') && modifiers.Control:
+		dot.Start = 0
+		dot.End   = len(this.text)
+		this.Select(dot)
+		return true
+	default:
+		return false
+	}
+}
+
+func (this *textBox) handleKeyUp (key input.Key, numberPad bool) bool {
+	if this.box.handleKeyUp(key, numberPad) { return true  }
+	if !this.selectable                     { return false }
+	
+	modifiers := this.Window().Modifiers()
+	switch {
+	case key == input.KeyHome || (modifiers.Alt && key == input.KeyLeft):
+		return true
+	case key == input.KeyEnd || (modifiers.Alt && key == input.KeyRight):
+		return true
+	case key == input.KeyLeft:
+		return true
+	case key == input.KeyRight:
+		return true
+	case key == input.Key('a') && modifiers.Control:
+		return true
+	default:
+		return false
+	}
+}
+
 func (this *textBox) normalizedLayoutBoundsSpace () image.Rectangle {
 	bounds := this.drawer.LayoutBoundsSpace()
 	return bounds.Sub(bounds.Min)
@@ -272,10 +415,10 @@ func (this *textBox) normalizedLayoutBoundsSpace () image.Rectangle {
 func (this *textBox) contentMinimum () image.Point {
 	minimum := this.drawer.MinimumSize()
 
-	if this.hOverflow || this.wrap {
+	if this.attrOverflow.Value().X || bool(this.attrWrap.Value()) {
 		minimum.X = this.drawer.Em().Round()
 	}
-	if this.vOverflow {
+	if this.attrOverflow.Value().Y {
 		minimum.Y = this.drawer.LineHeight().Round()
 	}
 
@@ -347,3 +490,36 @@ func (this *textBox) scrollToDot () {
 	
 	this.ScrollTo(scroll)
 }
+
+func (this *textBox) handleFaceChange () {
+	hierarchy := this.getHierarchy()
+	if hierarchy == nil { return }
+	faceSet := hierarchy.getFaceSet()
+	if faceSet == nil { return }
+	
+	face := faceSet.Face(tomo.Face(this.attrFace.Value()))
+	this.face.Set(face, face)
+	this.drawer.SetFace(face)
+	this.invalidateMinimum()
+	this.invalidateLayout()
+}
+
+func (this *textBox) recursiveReApply () {
+	this.box.recursiveReApply()
+	
+	hierarchy := this.getHierarchy()
+	if hierarchy == nil { return }
+	
+	previousFace := this.face.Value()
+	if previousFace == nil {
+		faceSet := hierarchy.getFaceSet()
+		if faceSet == nil { return }
+		face := faceSet.Face(tomo.Face(this.attrFace.Value()))
+		if face != previousFace {
+			this.face.Set(face, face)
+			this.drawer.SetFace(face)
+			this.invalidateMinimum()
+			this.invalidateLayout()
+		}
+	}
+}

internal/util/util.go

@@ -1,5 +1,6 @@
 package util
 
+import "io"
 import "image/color"
 
 // IndexOf returns the index of needle within haystack. If needle does not exist
@@ -82,6 +83,7 @@ func NewMemo[T any] (update func () T) Memo[T] {
 func (this *Memo[T]) Value () T {
 	if !this.valid {
 		this.cache = this.update()
+		this.valid = true
 	}
 	return this.cache
 }
@@ -89,13 +91,66 @@ func (this *Memo[T]) Value () T {
 // Invalidate marks the Memo's value as invalid, which will cause it to be
 // updated the next time Value is called.
 func (this *Memo[T]) Invalidate () {
+	var zero T
+	this.cache = zero
 	this.valid = false
 }
 
-// InvalidateTo invalidates the Memo and sets its value. The new value will be
-// entirely inaccessible. This is only intended to be used for setting a
-// reference to nil
-func (this *Memo[T]) InvalidateTo (value T) {
-	this.Invalidate()
-	this.cache = value
+// Cycler stores a value and an accompanying io.Closer. When the value is set,
+// the closer associated with the previous value is closed.
+type Cycler[T any] struct {
+	value  T
+	closer io.Closer
+}
+
+// Value returns the cycler's value.
+func (this *Cycler[T]) Value () T {
+	return this.value
+}
+
+// Set sets the value and associated closer, closing the previous one.
+func (this *Cycler[T]) Set (value T, closer io.Closer) (err error) {
+	if this.closer != nil {
+		err = this.closer.Close()
+	}
+	this.value  = value
+	this.closer = closer
+	return err
+}
+
+// Close closes the associated closer early.
+func (this *Cycler[T]) Close () error {
+	err := this.closer.Close()
+	this.closer = nil
+	return err
+}
+
+// Optional is an optional value.
+type Optional[T any] struct {
+	value T
+	exists bool
+}
+
+// Value returns the value and true if the value exists. If not, it returns the
+// last set value and false.
+func (this *Optional[T]) Value () (T, bool) {
+	return this.value, this.exists
+}
+
+// Set sets the value.
+func (this *Optional[T]) Set (value T) {
+	this.value = value
+	this.exists = true
+}
+
+// Unset unsets the value.
+func (this *Optional[T]) Unset () {
+	var zero T
+	this.value = zero
+	this.exists = false
+}
+
+// Exists returns if the value is currently set.
+func (this *Optional[T]) Exists () bool {
+	return this.exists
 }

style/faceset.go

@@ -0,0 +1,13 @@
+package style
+
+import "golang.org/x/image/font"
+import "git.tebibyte.media/tomo/tomo"
+
+// FaceSet holds a set of font faces.
+type FaceSet interface {
+	// Face returns the font face which most closely matches the given
+	// tomo.Face. The face must be closed when it is done being used. If no
+	// suitable face could be found, This behavior must return a fallback
+	// face (such as basicfont.Face7x13) instead of nil.
+	Face (tomo.Face) font.Face
+}

style/iconset.go

@@ -0,0 +1,28 @@
+package style
+
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/data"
+import "git.tebibyte.media/tomo/tomo/canvas"
+
+// IconSet holds a set of icon textures.
+type IconSet interface {
+	// A word on textures:
+	//
+	// Because textures can be linked to some resource that is outside of
+	// the control of Go's garbage collector, methods of IconSet must not
+	// allocate new copies of a texture each time they are called. It is
+	// fine to lazily load textures and save them for later use, but the
+	// same texture must never be allocated multiple times as this could
+	// cause a memory leak.
+	//
+	// As such, textures returned by these methods must be protected.
+	
+	// Icon returns a texture of the corresponding icon ID. If there is no
+	// suitable option, it should return nil.
+	Icon (tomo.Icon, tomo.IconSize) canvas.Texture
+
+	// MimeIcon returns a texture of an icon corresponding to a MIME type.
+	// If there is no suitable specific option, it should return a more
+	// generic icon or a plain file icon.
+	MimeIcon (data.Mime, tomo.IconSize) canvas.Texture
+}

style/style.go

@@ -0,0 +1,70 @@
+package style
+
+import "image/color"
+import "git.tebibyte.media/tomo/tomo"
+
+// Style can apply a visual style to different objects.
+type Style struct {
+	// Rules determines which styles get applied to which Objects.
+	Rules []Rule
+
+	// Colors maps tomo.Color values to color.RGBA values.
+	Colors map[tomo.Color] color.Color
+}
+
+// Rule describes under what circumstances should certain style attributes be
+// active.
+type Rule struct {
+	Role tomo.Role
+	Tags []string
+	Set  AttrSet
+}
+
+// Ru is shorthand for creating a rule structure
+func Ru (set AttrSet, role tomo.Role, tags ...string) Rule {
+	return Rule {
+		Role: role,
+		Tags: tags,
+		Set:  set,
+	}
+}
+
+// AttrSet is a set of attributes wherein only one/zero of each attribute type
+// can exist. It is keyed by the AttrKind of each attribute and must not be
+// modified directly.
+type AttrSet map[tomo.AttrKind] tomo.Attr
+
+// AS builds an AttrSet out of a vararg list of Attr values. If multiple Attrs
+// of the same kind are specified, the last one will override the others.
+func AS (attrs ...tomo.Attr) AttrSet {
+	set := AttrSet { }
+	set.Add(attrs...)
+	return set
+}
+
+// Add adds attributes to the set.
+func (this AttrSet) Add (attrs ...tomo.Attr) {
+	for _, attr := range attrs {
+		this[attr.Kind()] = attr
+	}
+}
+
+// MergeUnder takes attributes from another set and adds them if they don't
+// already exist in this one.
+func (this AttrSet) MergeUnder (other AttrSet) {
+	if other == nil { return }
+	for _, attr := range other {
+		if _, exists := this[attr.Kind()]; !exists {
+			this.Add(attr)
+		}
+	}
+}
+
+// MergeOver takes attributes from another set and adds them, overriding this
+// one.
+func (this AttrSet) MergeOver (other AttrSet) {
+	if other == nil { return }
+	for _, attr := range other {
+		this.Add(attr)
+	}
+}

x/backend.go

@@ -4,7 +4,9 @@ import "image"
 import "errors"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/xgbkb"
+import "git.tebibyte.media/tomo/tomo/data"
 import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/backend/style"
 import "git.tebibyte.media/tomo/backend/x/canvas"
 import "git.tebibyte.media/tomo/backend/internal/system"
 
@@ -18,6 +20,9 @@ type Backend struct {
 	x         *xgbutil.XUtil
 	system    *system.System
 
+	style     *style.Style
+	iconSet   style.IconSet
+	
 	doChannel chan func()
 	windows   map[xproto.Window] *window
 	open      bool
@@ -31,10 +36,6 @@ func (this *backendLink) NewTexture (source image.Image) canvas.TextureCloser {
 	return this.backend.NewTexture(source)
 }
 
-func (this *backendLink) NewCanvas (bounds image.Rectangle) canvas.Canvas {
-	return this.backend.NewCanvas(bounds)
-}
-
 func (this *backendLink) NewSurface (bounds image.Rectangle) (system.SurfaceLink, error) {
 	// TODO
 	return nil, errors.New("x: not implemented")
@@ -106,30 +107,59 @@ func (this *Backend) NewBox () tomo.Box {
 	return this.system.NewBox()
 }
 
-func (this *Backend) NewCanvasBox () tomo.CanvasBox {
-	return this.system.NewCanvasBox()
+func (this *Backend) NewTextBox () tomo.TextBox {
+	return this.system.NewTextBox()
 }
 
-func (this *Backend) NewContainerBox () tomo.ContainerBox {
-	return this.system.NewContainerBox()
+func (this *Backend) NewCanvasBox () tomo.CanvasBox {
+	return this.system.NewCanvasBox()
 }
 
 func (this *Backend) NewSurfaceBox () (tomo.SurfaceBox, error) {
 	return this.system.NewSurfaceBox()
 }
 
-func (this *Backend) NewTextBox () tomo.TextBox {
-	return this.system.NewTextBox()
+func (this *Backend) NewContainerBox () tomo.ContainerBox {
+	return this.system.NewContainerBox()
 }
 
 func (this *Backend) NewTexture (source image.Image) canvas.TextureCloser {
 	return xcanvas.NewTextureFrom(source)
 }
 
-func (this *Backend) NewCanvas (bounds image.Rectangle) canvas.Canvas {
+func (this *Backend) NewCanvas (bounds image.Rectangle) canvas.CanvasCloser {
 	return xcanvas.NewCanvas(this.x, bounds)
 }
 
+func (this *Backend) ColorRGBA (id tomo.Color) (r, g, b, a uint32) {
+	if col, ok := this.style.Colors[id]; ok {
+		return col.RGBA()
+	}
+	return 0xFFFF, 0, 0xFFFF, 0xFFFF // punish bad styles
+}
+
+func (this *Backend) IconTexture (id tomo.Icon, size tomo.IconSize) canvas.Texture {
+	return this.iconSet.Icon(id, size)
+}
+
+func (this *Backend) MimeIconTexture (mime data.Mime, size tomo.IconSize) canvas.Texture {
+	return this.iconSet.MimeIcon(mime, size)
+}
+
+func (this *Backend) SetStyle (style *style.Style) {
+	this.style = style
+	this.system.SetStyle(style)
+}
+
+func (this *Backend) SetIconSet (iconSet style.IconSet) {
+	this.iconSet = iconSet
+	this.system.SetIconSet(iconSet)
+}
+
+func (this *Backend) SetFaceSet (faceSet style.FaceSet) {
+	this.system.SetFaceSet(faceSet)
+}
+
 func (this *Backend) assert () {
 	if this == nil { panic("x: nil backend") }
 }

x/canvas/canvas.go

@@ -49,9 +49,10 @@ func (this *Canvas) Push (window xproto.Window) {
 }
 
 // Close frees this canvas from the X server.
-func (this *Canvas) Close () {
+func (this *Canvas) Close () error {
 	this.assert()
 	this.Image.Destroy()
+	return nil
 }
 
 func (this *Canvas) assert () {
@@ -131,3 +132,32 @@ func convertColor (c color.Color) xgraphics.BGRA {
 		A: uint8(a >> 8),
 	}
 }
+
+// For some reason, xgraphics.BGRA does not specify whether or not it uses
+// premultiplied alpha, and information regarding this is contradictory.
+// Basically:
+//   - BGRAModel just takes the result of c.RGBA and bit shifts it, without
+//     un-doing the aplha premultiplication that is required by Color.RGBA,
+//     suggesting that xgraphics.BGRA stores alpha-premultiplied color.
+//   - xgraphics.BlendBGRA lerps between dest and src using only the alpha of
+//     src (temporarily converting the colors to fucking floats for some reason)
+//     which seems to suggest that xgraphics.BGRA *does not* store alpha-
+//     premultiplied color.
+// There is no issues page on xgbutil so we may never get an answer to this
+// question. However, in this package we just use xgraphics.BGRA to store alpha-
+// premultiplied color anyway because its way faster, and I would sooner eat
+// spaghetti with a spoon than convert to and from float64 to blend pixels.
+func blendPremultipliedBGRA (dst, src xgraphics.BGRA) xgraphics.BGRA {
+	// https://en.wikipedia.org/wiki/Alpha_compositing
+	return xgraphics.BGRA {
+		B: blendPremultipliedChannel(dst.B, src.B, src.A),
+		G: blendPremultipliedChannel(dst.G, src.G, src.A),
+		R: blendPremultipliedChannel(dst.R, src.R, src.A),
+		A: blendPremultipliedChannel(dst.A, src.A, src.A),
+	}
+}
+
+func blendPremultipliedChannel (dst, src, a uint8) uint8 {
+	dst16, src16, a16 := uint16(dst), uint16(src), uint16(a)
+	return uint8(src16 + ((dst16 * (255 - a16)) >> 8))
+}

x/canvas/draw.go

@@ -1,6 +1,7 @@
 package xcanvas
 
 import "sort"
+import "math"
 import "image"
 import "github.com/jezek/xgbutil/xgraphics"
 
@@ -45,7 +46,7 @@ func (this *pen) textureRectangleTransparent (bounds image.Rectangle) {
 		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 {
+		pixel := blendPremultipliedBGRA(xgraphics.BGRA {
 			B: dst[dstIndex + 0],
 			G: dst[dstIndex + 1],
 			R: dst[dstIndex + 2],
@@ -92,7 +93,7 @@ func (this *pen) fillRectangleTransparent (c xgraphics.BGRA, bounds image.Rectan
 	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 {
+		pixel := blendPremultipliedBGRA(xgraphics.BGRA {
 			B: this.image.Pix[index + 0],
 			G: this.image.Pix[index + 1],
 			R: this.image.Pix[index + 2],
@@ -158,12 +159,12 @@ func (this *pen) fillPolygon (c xgraphics.BGRA, points ...image.Point) {
 	area = this.image.Bounds().Intersect(area)
 	if area.Empty() { return }
 
+	boundaries := make([]int, len(points))
 	context := fillingContext {
 		image:      this.image,
 		color:      this.fill,
 		min:        area.Min.X,
 		max:        area.Max.X,
-		boundaries: make([]int, len(points)),
 		points:     points,
 	}
 
@@ -181,19 +182,19 @@ func (this *pen) fillPolygon (c xgraphics.BGRA, points ...image.Point) {
 				(fPointY < fy && fPrevY  >= fy) ||
 				(fPrevY  < fy && fPointY >= fy)
 			if addboundary {
-				context.boundaries[boundaryCount] = int (
+				boundaries[boundaryCount] = int(math.Round (
 					fPointX +
 					(fy - fPointY) /
 					(fPrevY - fPointY) *
-					(fPrevX - fPointX))
+					(fPrevX - fPointX)))
 				boundaryCount ++
 			}
 			prevPoint = point
 		}
 
 		// sort boundary list
-		cutBoundaries := context.boundaries[:boundaryCount]
-		sort.Ints(cutBoundaries)
+		context.boundaries = boundaries[:boundaryCount]
+		sort.Ints(context.boundaries)
 
 		// fill pixels between boundary pairs
 		if c.A == 255 {
@@ -215,7 +216,7 @@ type fillingContext struct {
 }
 
 func (context *fillingContext) fillPolygonHotOpaque () {
-	for index := 0; index < len(context.boundaries); index += 2 {
+	for index := 0; index < len(context.boundaries) - 1; index += 2 {
 		left  := context.boundaries[index]
 		right := context.boundaries[index + 1]
 
@@ -240,7 +241,7 @@ func (context *fillingContext) fillPolygonHotOpaque () {
 }
 
 func (context *fillingContext) fillPolygonHotTransparent () {
-	for index := 0; index < len(context.boundaries); index += 2 {
+	for index := 0; index < len(context.boundaries) - 1; index += 2 {
 		left  := context.boundaries[index]
 		right := context.boundaries[index + 1]
 
@@ -255,7 +256,7 @@ func (context *fillingContext) fillPolygonHotTransparent () {
 			// fill pixels in between
 			for x := left; x < right; x ++ {
 				index := context.image.PixOffset(x, context.y)
-				pixel := xgraphics.BlendBGRA(xgraphics.BGRA {
+				pixel := blendPremultipliedBGRA(xgraphics.BGRA {
 					B: context.image.Pix[index + 0],
 					G: context.image.Pix[index + 1],
 					R: context.image.Pix[index + 2],

x/canvas/plot.go

@@ -32,7 +32,7 @@ func (context plottingContext) plot (center image.Point) {
 		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 {
+			pixel := blendPremultipliedBGRA(xgraphics.BGRA {
 				B: context.image.Pix[index + 0],
 				G: context.image.Pix[index + 1],
 				R: context.image.Pix[index + 2],

x/event.go

@@ -13,7 +13,7 @@ type scrollSum struct {
 }
 
 // TODO: this needs to be configurable, we need a config api
-const scrollDistance = 16
+const scrollDistance = 32
 
 func (sum *scrollSum) add (button xproto.Button, window *window, state uint16) {
 	if xgbkb.StateToModifiers(state).Shift {

x/window.go

@@ -4,6 +4,7 @@ import "image"
 
 import "git.tebibyte.media/tomo/tomo"
 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 "git.tebibyte.media/tomo/backend/x/canvas"
@@ -18,7 +19,6 @@ import "github.com/jezek/xgbutil/keybind"
 import "github.com/jezek/xgbutil/mousebind"
 import "github.com/jezek/xgbutil/xgraphics"
 
-type mainWindow struct { *window }
 type window struct {
 	backend   *Backend
 	hierarchy *system.Hierarchy
@@ -28,10 +28,13 @@ type window struct {
 
 	title string
 
+	leader      *window
 	modalParent *window
 	hasModal    bool
 	shy         bool
 	visible     bool
+	resizeX     bool
+	resizeY     bool
 
 	metrics struct {
 		bounds image.Rectangle
@@ -63,28 +66,24 @@ func (this *windowLink) NotifyMinimumSizeChange () {
 func (this *Backend) NewWindow (
 	bounds image.Rectangle,
 ) (
-	output tomo.MainWindow,
+	output tomo.Window,
 	err error,
 ) {
 	this.assert()
-	window, err := this.newWindow(bounds, false)
-	
-	output = mainWindow { window: window }
-	return output, err
+	return this.newWindow(bounds, false)
 }
 
 func (this *Backend) NewPlainWindow (
 	bounds image.Rectangle,
 ) (
-	output tomo.MainWindow,
+	output tomo.Window,
 	err error,
 ) {
 	this.assert()
 	window, err := this.newWindow(bounds, false)
 	window.setType("dock")
 	
-	output = mainWindow { window: window }
-	return output, err
+	return window, err
 }
 
 func (this *Backend) newWindow (
@@ -100,6 +99,9 @@ func (this *Backend) newWindow (
 	window := &window     { backend: this   }
 	link   := &windowLink { window:  window }
 	window.hierarchy = this.system.NewHierarchy(link)
+	window.leader    = window
+	window.resizeX   = true
+	window.resizeY   = true
 
 	window.xWindow, err = xwindow.Generate(this.x)
 	if err != nil { return }
@@ -178,12 +180,21 @@ func (this *window) SetTitle (title string) {
 	icccm.WmIconNameSet (this.backend.x, this.xWindow.Id, title)
 }
 
-func (this *window) SetIcon (sizes ...image.Image) {
+func (this *window) SetIcon (icon tomo.Icon) {
+	textures := []canvas.Texture {
+		icon.Texture(tomo.IconSizeSmall),
+		icon.Texture(tomo.IconSizeMedium),
+		icon.Texture(tomo.IconSizeLarge),
+	}
+	
 	wmIcons := []ewmh.WmIcon { }
 
-	for _, icon := range sizes {
-		width  := icon.Bounds().Max.X
-		height := icon.Bounds().Max.Y
+	for _, icon := range textures {
+		icon := xcanvas.AssertTexture(icon)
+		
+		bounds := icon.Bounds()
+		width  := bounds.Dx()
+		height := bounds.Dy()
 		wmIcon := ewmh.WmIcon {
 			Width:  uint(width),
 			Height: uint(height),
@@ -193,18 +204,14 @@ func (this *window) SetIcon (sizes ...image.Image) {
 		// manually convert image data beacuse of course we have to do
 		// this
 		index := 0
-		for y := 0; y < height; y ++ {
-		for x := 0; x < width;  x ++ {
-			r, g, b, a := icon.At(x, y).RGBA()
-			r >>= 8
-			g >>= 8
-			b >>= 8
-			a >>= 8
+		for y := bounds.Min.Y; y < bounds.Max.Y; y ++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x ++ {
+			pixel := icon.BGRAAt(x, y)
 			wmIcon.Data[index] =
-				(uint(a) << 24) |
-				(uint(r) << 16) |
-				(uint(g) << 8)  |
-				(uint(b) << 0)
+				(uint(pixel.A) << 24) |
+				(uint(pixel.R) << 16) |
+				(uint(pixel.G) << 8)  |
+				(uint(pixel.B) << 0)
 			index ++
 		}}
 		
@@ -217,6 +224,40 @@ func (this *window) SetIcon (sizes ...image.Image) {
 		wmIcons)
 }
 
+func (this *window) SetResizable (x, y bool) {
+	if this.resizeX == x && this.resizeY == y { return }
+	this.resizeX = x
+	this.resizeY = y
+	this.doMinimumSize()
+}
+
+func (this *window) SetBounds (bounds image.Rectangle) {
+	this.xWindow.WMMoveResize (
+		bounds.Min.X, bounds.Min.Y,
+		bounds.Min.X + bounds.Dx(),
+		bounds.Min.Y + bounds.Dy())
+}
+
+func (this *window) NewChild (bounds image.Rectangle) (tomo.Window, error) {
+	leader := this.leader
+	
+	child, err := this.backend.newWindow (
+		bounds.Add(this.metrics.bounds.Min), false)
+	child.leader = leader
+	if err != nil { return nil, err }
+	
+	child.setClientLeader(leader)
+	leader.setClientLeader(leader)
+	
+	icccm.WmTransientForSet (
+		this.backend.x,
+		child.xWindow.Id,
+		leader.xWindow.Id)
+	child.setType("UTILITY")
+	// child.inheritProperties(leader.window)
+	return child, err
+}
+
 func (this *window) NewMenu (bounds image.Rectangle) (tomo.Window, error) {
 	menu, err := this.backend.newWindow (
 		bounds.Add(this.metrics.bounds.Min), true)
@@ -247,24 +288,12 @@ func (this *window) NewModal (bounds image.Rectangle) (tomo.Window, error) {
 	return modal, err
 }
 
-func (this mainWindow) NewChild (bounds image.Rectangle) (tomo.Window, error) {
-	child, err := this.backend.newWindow (
-		bounds.Add(this.metrics.bounds.Min), false)
-	if err != nil { return nil, err }
-	child.setClientLeader(this.window)
-	this.setClientLeader(this.window)
-	icccm.WmTransientForSet (
-		this.backend.x,
-		this.xWindow.Id,
-		this.xWindow.Id)
-	this.setType("UTILITY")
-	// this.inheritProperties(this.window)
-	return this, err
+func (this *window) Modifiers () input.Modifiers {
+	return this.hierarchy.Modifiers()
 }
 
-func (this *window) Widget () (tomo.Window, error) {
-	// TODO
-	return nil, nil
+func (this *window) MousePosition () image.Point {
+	return this.hierarchy.MousePosition()
 }
 
 func (this *window) Copy (data.Data) {
@@ -306,6 +335,7 @@ func (this *window) Close () {
 	this.SetRoot(nil)
 	delete(this.backend.windows, this.xWindow.Id)
 	this.xWindow.Destroy()
+	this.hierarchy.Close()
 }
 
 func (this *window) OnClose (callback func ()) event.Cookie {
@@ -361,7 +391,7 @@ func (this *window) reallocateCanvas () {
 	
 	if larger || smaller {
 		if this.xCanvas != nil {
-			this.xCanvas.Destroy()
+			this.xCanvas.Close()
 		}
 		this.xCanvas = xcanvas.NewCanvasFrom(xgraphics.New (
 			this.backend.x,
@@ -404,14 +434,30 @@ func (this *window) doMinimumSize () {
 	
 	if size.X < 8 { size.X = 8 }
 	if size.Y < 8 { size.Y = 8 }
+
+	hints := icccm.NormalHints {
+		Flags:     icccm.SizeHintPMinSize,
+		MinWidth:  uint(size.X),
+		MinHeight: uint(size.Y),
+		// now you can tell your friends that the max size of a Tomo
+		// window under X when one of the dimensions is constrained is
+		// 99999999999
+		MaxWidth:  uint(99999999999),
+		MaxHeight: uint(99999999999),
+	}
+	if !this.resizeX {
+		hints.Flags   |= icccm.SizeHintPMaxSize
+		hints.MaxWidth = uint(size.X)
+	}
+	if !this.resizeY {
+		hints.Flags    |= icccm.SizeHintPMaxSize
+		hints.MaxHeight = uint(size.Y)
+	}
+	
 	icccm.WmNormalHintsSet (
 		this.backend.x,
 		this.xWindow.Id,
-		&icccm.NormalHints {
-			Flags:     icccm.SizeHintPMinSize,
-			MinWidth:  uint(size.X),
-			MinHeight: uint(size.Y),
-		})
+		&hints)
 	newWidth  := this.metrics.bounds.Dx()
 	newHeight := this.metrics.bounds.Dy()
 	if newWidth  < size.X { newWidth  = size.X }