Basic elements now conform to new API

elements/basic/button.go

@@ -35,9 +35,9 @@ type Button struct {
 func NewButton (text string) (element *Button) {
 	element = &Button { showText: true }
 	element.theme.Case = theme.C("basic", "button")
-	element.Core, element.core = core.NewCore(element.drawAll)
+	element.Core, element.core = core.NewCore(element, element.drawAll)
 	element.FocusableCore,
-	element.focusableControl = core.NewFocusableCore(element.drawAndPush)
+	element.focusableControl = core.NewFocusableCore(element.core, element.drawAndPush)
 	element.SetText(text)
 	return
 }
@@ -61,9 +61,6 @@ func (element *Button) HandleMouseUp (x, y int, button input.Button) {
 	element.drawAndPush()
 }
 
-func (element *Button) HandleMouseMove (x, y int) { }
-func (element *Button) HandleMouseScroll (x, y int, deltaX, deltaY float64) { }
-
 func (element *Button) HandleKeyDown (key input.Key, modifiers input.Modifiers) {
 	if !element.Enabled() { return }
 	if key == input.KeyEnter {

elements/basic/checkbox.go

@@ -29,9 +29,9 @@ type Checkbox struct {
 func NewCheckbox (text string, checked bool) (element *Checkbox) {
 	element = &Checkbox { checked: checked }
 	element.theme.Case = theme.C("basic", "checkbox")
-	element.Core, element.core = core.NewCore(element.draw)
+	element.Core, element.core = core.NewCore(element, element.draw)
 	element.FocusableCore,
-	element.focusableControl = core.NewFocusableCore(element.redo)
+	element.focusableControl = core.NewFocusableCore(element.core, element.redo)
 	element.SetText(text)
 	return
 }
@@ -65,9 +65,6 @@ func (element *Checkbox) HandleMouseUp (x, y int, button input.Button) {
 	}
 }
 
-func (element *Checkbox) HandleMouseMove (x, y int) { }
-func (element *Checkbox) HandleMouseScroll (x, y int, deltaX, deltaY float64) { }
-
 func (element *Checkbox) HandleKeyDown (key input.Key, modifiers input.Modifiers) {
 	if key == input.KeyEnter {
 		element.pressed = true

elements/basic/container.go

@@ -32,8 +32,8 @@ type Container struct {
 func NewContainer (layout layouts.Layout) (element *Container) {
 	element = &Container { }
 	element.theme.Case = theme.C("basic", "container")
-	element.Core, element.core = core.NewCore(element.redoAll)
+	element.Core, element.core = core.NewCore(element, element.redoAll)
-	element.Propagator = core.NewPropagator(element)
+	element.Propagator = core.NewPropagator(element, element.core)
 	element.SetLayout(layout)
 	return
 }
@@ -51,33 +51,13 @@ func (element *Container) SetLayout (layout layouts.Layout) {
 // the element will expand (instead of contract to its minimum size), in
 // whatever way is defined by the current layout.
 func (element *Container) Adopt (child elements.Element, expand bool) {
-	// set event handlers
 	if child0, ok := child.(elements.Themeable); ok {
 		child0.SetTheme(element.theme.Theme)
 	}
 	if child0, ok := child.(elements.Configurable); ok {
 		child0.SetConfig(element.config.Config)
 	}
-	child.OnDamage (func (region canvas.Canvas) {
+	child.SetParent(element)
-		element.core.DamageRegion(region.Bounds())
-	})
-	child.OnMinimumSizeChange (func () {
-		// TODO: this could probably stand to be more efficient. I mean
-		// seriously?
-		element.updateMinimumSize()
-		element.redoAll()
-		element.core.DamageAll()
-	})
-	if child0, ok := child.(elements.Focusable); ok {
-		child0.OnFocusRequest (func () (granted bool) {
-			return element.childFocusRequestCallback(child0)
-		})
-		child0.OnFocusMotionRequest (
-			func (direction input.KeynavDirection) (granted bool) {
-				if element.onFocusMotionRequest == nil { return }
-				return element.onFocusMotionRequest(direction)
-			})
-	}
 
 	// add child
 	element.children = append (element.children, layouts.LayoutEntry {
@@ -136,14 +116,12 @@ func (element *Container) Disown (child elements.Element) {
 }
 
 func (element *Container) clearChildEventHandlers (child elements.Element) {
-	child.DrawTo(nil, image.Rectangle { })
+	child.DrawTo(nil, image.Rectangle { }, nil)
-	child.OnDamage(nil)
+	child.SetParent(nil)
-	child.OnMinimumSizeChange(nil)
+	
-	if child0, ok := child.(elements.Focusable); ok {
+	if child, ok := child.(elements.Focusable); ok {
-		child0.OnFocusRequest(nil)
+		if child.Focused() {
-		child0.OnFocusMotionRequest(nil)
+			child.HandleUnfocus()
-		if child0.Focused() {
-			child0.HandleUnfocus()
 		}
 	}
 }
@@ -200,7 +178,7 @@ func (element *Container) redoAll () {
 	// remove child canvasses so that any operations done in here will not
 	// cause a child to draw to a wack ass canvas.
 	for _, entry := range element.children {
-		entry.DrawTo(nil, entry.Bounds)
+		entry.DrawTo(nil, entry.Bounds, nil)
 	}
 	
 	// do a layout
@@ -220,10 +198,20 @@ func (element *Container) redoAll () {
 	for _, entry := range element.children {
 		entry.DrawTo (
 			canvas.Cut(element.core, entry.Bounds),
-			entry.Bounds)
+			entry.Bounds, func (region image.Rectangle) {
+				element.core.DamageRegion(region)
+			})
 	}
 }
 
+// NotifyMinimumSizeChange notifies the container that the minimum size of a
+// child element has changed.
+func (element *Container) NotifyMinimumSizeChange (child elements.Element) {
+	element.updateMinimumSize()
+	element.redoAll()
+	element.core.DamageAll()
+}
+
 // SetTheme sets the element's theme.
 func (element *Container) SetTheme (new theme.Theme) {
 	if new == element.theme.Theme { return }
@@ -241,32 +229,6 @@ func (element *Container) SetConfig (new config.Config) {
 	element.redoAll()
 }
 
-func (element *Container) OnFocusRequest (callback func () (granted bool)) {
-	element.onFocusRequest = callback
-	element.Propagator.OnFocusRequest(callback)
-}
-
-func (element *Container) OnFocusMotionRequest (
-	callback func (direction input.KeynavDirection) (granted bool),
-) {
-	element.onFocusMotionRequest = callback
-	element.Propagator.OnFocusMotionRequest(callback)
-}
-
-func (element *Container) childFocusRequestCallback (
-	child elements.Focusable,
-) (
-	granted bool,
-) {
-	if element.onFocusRequest != nil && element.onFocusRequest() {
-		element.Propagator.HandleUnfocus()
-		element.Propagator.HandleFocus(input.KeynavDirectionNeutral)
-		return true
-	} else {
-		return false
-	}
-}
-
 func (element *Container) updateMinimumSize () {
 	margin  := element.theme.Margin(theme.PatternBackground)
 	padding := element.theme.Padding(theme.PatternBackground)

elements/basic/documentContainer.go

@@ -1,7 +1,6 @@
 package basicElements
 
 import "image"
-import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/theme"
 import "git.tebibyte.media/sashakoshka/tomo/config"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
@@ -22,18 +21,14 @@ type DocumentContainer struct {
 	
 	config config.Wrapped
 	theme  theme.Wrapped
-	
-	onFocusRequest       func () (granted bool)
-	onFocusMotionRequest func (input.KeynavDirection) (granted bool)
-	onScrollBoundsChange func ()
 }
 
 // NewDocumentContainer creates a new document container.
 func NewDocumentContainer () (element *DocumentContainer) {
 	element = &DocumentContainer { }
 	element.theme.Case = theme.C("basic", "documentContainer")
-	element.Core, element.core = core.NewCore(element.redoAll)
+	element.Core, element.core = core.NewCore(element, element.redoAll)
-	element.Propagator = core.NewPropagator(element)
+	element.Propagator = core.NewPropagator(element, element.core)
 	return
 }
 
@@ -46,29 +41,12 @@ func (element *DocumentContainer) Adopt (child elements.Element) {
 	if child0, ok := child.(elements.Configurable); ok {
 		child0.SetConfig(element.config.Config)
 	}
-	child.OnDamage (func (region canvas.Canvas) {
+	// if child0, ok := child.(elements.Flexible); ok {
-		element.core.DamageRegion(region.Bounds())
+		// child0.OnFlexibleHeightChange (func () {
-	})
+			// element.redoAll()
-	child.OnMinimumSizeChange (func () {
+			// element.core.DamageAll()
-		element.redoAll()
+		// })
-		element.core.DamageAll()
+	// }
-	})
-	if child0, ok := child.(elements.Flexible); ok {
-		child0.OnFlexibleHeightChange (func () {
-			element.redoAll()
-			element.core.DamageAll()
-		})
-	}
-	if child0, ok := child.(elements.Focusable); ok {
-		child0.OnFocusRequest (func () (granted bool) {
-			return element.childFocusRequestCallback(child0)
-		})
-		child0.OnFocusMotionRequest (
-			func (direction input.KeynavDirection) (granted bool) {
-				if element.onFocusMotionRequest == nil { return }
-				return element.onFocusMotionRequest(direction)
-			})
-	}
 
 	// add child
 	element.children = append (element.children, layouts.LayoutEntry {
@@ -123,14 +101,12 @@ func (element *DocumentContainer) Disown (child elements.Element) {
 }
 
 func (element *DocumentContainer) clearChildEventHandlers (child elements.Element) {
-	child.DrawTo(nil, image.Rectangle { })
+	child.DrawTo(nil, image.Rectangle { }, nil)
-	child.OnDamage(nil)
+	child.SetParent(nil)
-	child.OnMinimumSizeChange(nil)
+	
-	if child0, ok := child.(elements.Focusable); ok {
+	if child, ok := child.(elements.Focusable); ok {
-		child0.OnFocusRequest(nil)
+		if child.Focused() {
-		child0.OnFocusMotionRequest(nil)
+			child.HandleUnfocus()
-		if child0.Focused() {
-			child0.HandleUnfocus()
 		}
 	}
 }
@@ -204,14 +180,14 @@ func (element *DocumentContainer) redoAll () {
 	artist.DrawShatter(element.core, pattern, element.Bounds(), rocks...)
 
 	element.partition()
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 
 func (element *DocumentContainer) partition () {
 	for _, entry := range element.children {
-		entry.DrawTo(nil, entry.Bounds)
+		entry.DrawTo(nil, entry.Bounds, nil)
 	}
 
 	// cut our canvas up and give peices to child elements
@@ -219,11 +195,20 @@ func (element *DocumentContainer) partition () {
 		if entry.Bounds.Overlaps(element.Bounds()) {
 			entry.DrawTo (	
 				canvas.Cut(element.core, entry.Bounds),
-				entry.Bounds)
+				entry.Bounds, func (region image.Rectangle) {
+					element.core.DamageRegion(region)
+				})
 		}
 	}
 }
 
+// NotifyMinimumSizeChange notifies the container that the minimum size of a
+// child element has changed.
+func (element *DocumentContainer) NotifyMinimumSizeChange (child elements.Element) {
+	element.redoAll()
+	element.core.DamageAll()
+}
+
 // SetTheme sets the element's theme.
 func (element *DocumentContainer) SetTheme (new theme.Theme) {
 	if new == element.theme.Theme { return }
@@ -239,18 +224,6 @@ func (element *DocumentContainer) SetConfig (new config.Config) {
 	element.redoAll()
 }
 
-func (element *DocumentContainer) OnFocusRequest (callback func () (granted bool)) {
-	element.onFocusRequest = callback
-	element.Propagator.OnFocusRequest(callback)
-}
-
-func (element *DocumentContainer) OnFocusMotionRequest (
-	callback func (direction input.KeynavDirection) (granted bool),
-) {
-	element.onFocusMotionRequest = callback
-	element.Propagator.OnFocusMotionRequest(callback)
-}
-
 // ScrollContentBounds returns the full content size of the element.
 func (element *DocumentContainer) ScrollContentBounds () image.Rectangle {
 	return element.contentBounds
@@ -295,12 +268,6 @@ func (element *DocumentContainer) ScrollAxes () (horizontal, vertical bool) {
 	return false, true
 }
 
-// OnScrollBoundsChange sets a function to be called when the element's
-// ScrollContentBounds, ScrollViewportBounds, or ScrollAxes are changed.
-func (element *DocumentContainer) OnScrollBoundsChange(callback func()) {
-	element.onScrollBoundsChange = callback
-}
-
 func (element *DocumentContainer) reflectChildProperties () {
 	focusable := false
 	for _, entry := range element.children {
@@ -315,20 +282,6 @@ func (element *DocumentContainer) reflectChildProperties () {
 	}
 }
 
-func (element *DocumentContainer) childFocusRequestCallback (
-	child elements.Focusable,
-) (
-	granted bool,
-) {
-	if element.onFocusRequest != nil && element.onFocusRequest() {
-		element.Propagator.HandleUnfocus()
-		element.Propagator.HandleFocus(input.KeynavDirectionNeutral)
-		return true
-	} else {
-		return false
-	}
-}
-
 func (element *DocumentContainer) doLayout () {
 	margin := element.theme.Margin(theme.PatternBackground)
 	padding := element.theme.Padding(theme.PatternBackground)

elements/basic/icon.go

@@ -19,7 +19,7 @@ func NewIcon (id theme.Icon, size theme.IconSize) (element *Icon) {
 		size: size,
 	}
 	element.theme.Case = theme.C("basic", "icon")
-	element.Core, element.core = core.NewCore(element.draw)
+	element.Core, element.core = core.NewCore(element, element.draw)
 	element.updateMinimumSize()
 	return
 }

elements/basic/image.go

@@ -13,7 +13,7 @@ type Image struct {
 
 func NewImage (image image.Image) (element *Image) {
 	element = &Image { buffer: canvas.FromImage(image) }
-	element.Core, element.core = core.NewCore(element.draw)
+	element.Core, element.core = core.NewCore(element, element.draw)
 	bounds := image.Bounds()
 	element.core.SetMinimumSize(bounds.Dx(), bounds.Dy())
 	return

elements/basic/label.go

@@ -29,7 +29,7 @@ type Label struct {
 func NewLabel (text string, wrap bool) (element *Label) {
 	element = &Label { }
 	element.theme.Case = theme.C("basic", "label")
-	element.Core, element.core = core.NewCore(element.handleResize)
+	element.Core, element.core = core.NewCore(element, element.handleResize)
 	element.SetWrap(wrap)
 	element.SetText(text)
 	return

elements/basic/list.go

@@ -7,6 +7,7 @@ import "git.tebibyte.media/sashakoshka/tomo/theme"
 import "git.tebibyte.media/sashakoshka/tomo/config"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
+import "git.tebibyte.media/sashakoshka/tomo/elements"
 import "git.tebibyte.media/sashakoshka/tomo/elements/core"
 
 // List is an element that contains several objects that a user can select.
@@ -29,7 +30,6 @@ type List struct {
 	config config.Wrapped
 	theme  theme.Wrapped
 	
-	onScrollBoundsChange func ()
 	onNoEntrySelected func ()
 }
 
@@ -37,9 +37,9 @@ type List struct {
 func NewList (entries ...ListEntry) (element *List) {
 	element = &List { selectedEntry: -1 }
 	element.theme.Case = theme.C("basic", "list")
-	element.Core, element.core = core.NewCore(element.handleResize)
+	element.Core, element.core = core.NewCore(element, element.handleResize)
 	element.FocusableCore,
-	element.focusableControl = core.NewFocusableCore (func () {
+	element.focusableControl = core.NewFocusableCore (element.core, func () {
 		if element.core.HasImage () {
 			element.draw()
 			element.core.DamageAll()
@@ -64,8 +64,8 @@ func (element *List) handleResize () {
 		element.scroll = element.maxScrollHeight()
 	}
 	element.draw()
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 
@@ -102,8 +102,8 @@ func (element *List) redo () {
 		element.draw()
 		element.core.DamageAll()
 	}
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 
@@ -210,8 +210,8 @@ func (element *List) ScrollTo (position image.Point) {
 		element.draw()
 		element.core.DamageAll()
 	}
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 
@@ -233,10 +233,6 @@ func (element *List) maxScrollHeight () (height int) {
 	return
 }
 
-func (element *List) OnScrollBoundsChange (callback func ()) {
-	element.onScrollBoundsChange = callback
-}
-
 // OnNoEntrySelected sets a function to be called when the user chooses to
 // deselect the current selected entry by clicking on empty space within the
 // list or by pressing the escape key.
@@ -263,8 +259,8 @@ func (element *List) Append (entry ListEntry) {
 		element.draw()
 		element.core.DamageAll()
 	}
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 
@@ -296,8 +292,8 @@ func (element *List) Insert (index int, entry ListEntry) {
 		element.draw()
 		element.core.DamageAll()
 	}
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 
@@ -319,8 +315,8 @@ func (element *List) Remove (index int) {
 		element.draw()
 		element.core.DamageAll()
 	}
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 
@@ -341,8 +337,8 @@ func (element *List) Replace (index int, entry ListEntry) {
 		element.draw()
 		element.core.DamageAll()
 	}
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 

elements/basic/progressbar.go

@@ -20,7 +20,7 @@ type ProgressBar struct {
 func NewProgressBar (progress float64) (element *ProgressBar) {
 	element = &ProgressBar { progress: progress }
 	element.theme.Case = theme.C("basic", "progressBar")
-	element.Core, element.core = core.NewCore(element.draw)
+	element.Core, element.core = core.NewCore(element, element.draw)
 	return
 }
 

elements/basic/scrollbar.go

@@ -49,7 +49,7 @@ func NewScrollBar (vertical bool) (element *ScrollBar) {
 	} else {
 		element.theme.Case = theme.C("basic", "scrollBarVertical")
 	}
-	element.Core, element.core = core.NewCore(element.handleResize)
+	element.Core, element.core = core.NewCore(element, element.handleResize)
 	element.updateMinimumSize()
 	return
 }

elements/basic/scrollcontainer.go

@@ -31,12 +31,12 @@ type ScrollContainer struct {
 func NewScrollContainer (horizontal, vertical bool) (element *ScrollContainer) {
 	element = &ScrollContainer { }
 	element.theme.Case = theme.C("basic", "scrollContainer")
-	element.Core, element.core = core.NewCore(element.redoAll)
+	element.Core, element.core = core.NewCore(element, element.redoAll)
-	element.Propagator = core.NewPropagator(element)
+	element.Propagator = core.NewPropagator(element, element.core)
 
 	if horizontal {
 		element.horizontal = NewScrollBar(false)
-		element.setChildEventHandlers(element.horizontal)
+		element.setUpChild(element.horizontal)
 		element.horizontal.OnScroll (func (viewport image.Point) {
 			if element.child != nil {
 				element.child.ScrollTo(viewport)
@@ -50,7 +50,7 @@ func NewScrollContainer (horizontal, vertical bool) (element *ScrollContainer) {
 	}
 	if vertical {
 		element.vertical = NewScrollBar(true)
-		element.setChildEventHandlers(element.vertical)
+		element.setUpChild(element.vertical)
 		element.vertical.OnScroll (func (viewport image.Point) {
 			if element.child != nil {
 				element.child.ScrollTo(viewport)
@@ -72,13 +72,13 @@ func NewScrollContainer (horizontal, vertical bool) (element *ScrollContainer) {
 func (element *ScrollContainer) Adopt (child elements.Scrollable) {
 	// disown previous child if it exists
 	if element.child != nil {
-		element.clearChildEventHandlers(child)
+		element.disownChild(child)
 	}
 
 	// adopt new child
 	element.child = child
 	if child != nil {
-		element.setChildEventHandlers(child)
+		element.setUpChild(child)
 	}
 	
 	element.updateEnabled()
@@ -89,50 +89,47 @@ func (element *ScrollContainer) Adopt (child elements.Scrollable) {
 	}
 }
 
-func (element *ScrollContainer) setChildEventHandlers (child elements.Element) {
+func (element *ScrollContainer) setUpChild (child elements.Element) {
-	if child0, ok := child.(elements.Themeable); ok {
+	child.SetParent(element)
-		child0.SetTheme(element.theme.Theme)
+	if child, ok := child.(elements.Themeable); ok {
+		child.SetTheme(element.theme.Theme)
 	}
-	if child0, ok := child.(elements.Configurable); ok {
+	if child, ok := child.(elements.Configurable); ok {
-		child0.SetConfig(element.config.Config)
+		child.SetConfig(element.config.Config)
-	}
-	child.OnDamage (func (region canvas.Canvas) {
-		element.core.DamageRegion(region.Bounds())
-	})
-	child.OnMinimumSizeChange (func () {
-		element.updateMinimumSize()
-		element.redoAll()
-		element.core.DamageAll()
-	})
-	if child0, ok := child.(elements.Focusable); ok {
-		child0.OnFocusRequest (func () (granted bool) {
-			return element.childFocusRequestCallback(child0)
-		})
-		child0.OnFocusMotionRequest (
-			func (direction input.KeynavDirection) (granted bool) {
-				if element.onFocusMotionRequest == nil { return }
-				return element.onFocusMotionRequest(direction)
-			})
-	}
-	if child0, ok := child.(elements.Scrollable); ok {
-		child0.OnScrollBoundsChange(element.childScrollBoundsChangeCallback)
 	}
 }
 
-func (element *ScrollContainer) clearChildEventHandlers (child elements.Scrollable) {
+func (element *ScrollContainer) disownChild (child elements.Scrollable) {
-	child.DrawTo(nil, image.Rectangle { })
+	child.DrawTo(nil, image.Rectangle { }, nil)
-	child.OnDamage(nil)
+	child.SetParent(nil)
-	child.OnMinimumSizeChange(nil)
+	if child, ok := child.(elements.Focusable); ok {
-	child.OnScrollBoundsChange(nil)
+		if child.Focused() {
-	if child0, ok := child.(elements.Focusable); ok {
+			child.HandleUnfocus()
-		child0.OnFocusRequest(nil)
-		child0.OnFocusMotionRequest(nil)
-		if child0.Focused() {
-			child0.HandleUnfocus()
 		}
 	}
 }
 
+// NotifyMinimumSizeChange notifies the container that the minimum size of a
+// child element has changed.
+func (element *ScrollContainer) NotifyMinimumSizeChange (child elements.Element) {
+	element.redoAll()
+	element.core.DamageAll()
+}
+
+// NotifyScrollBoundsChange notifies the container that the scroll bounds or
+// axes of a child have changed.
+func (element *ScrollContainer) NotifyScrollBoundsChange (child elements.Scrollable) {
+	element.updateEnabled()
+	viewportBounds := element.child.ScrollViewportBounds()
+	contentBounds  := element.child.ScrollContentBounds()
+	if element.horizontal != nil {
+		element.horizontal.SetBounds(contentBounds, viewportBounds)
+	}
+	if element.vertical != nil {
+		element.vertical.SetBounds(contentBounds, viewportBounds)
+	}
+}
+
 // SetTheme sets the element's theme.
 func (element *ScrollContainer) SetTheme (new theme.Theme) {
 	if new == element.theme.Theme { return }
@@ -157,18 +154,6 @@ func (element *ScrollContainer) HandleMouseScroll (
 	element.scrollChildBy(int(deltaX), int(deltaY))
 }
 
-func (element *ScrollContainer) OnFocusRequest (callback func () (granted bool)) {
-	element.onFocusRequest = callback
-	element.Propagator.OnFocusRequest(callback)
-}
-
-func (element *ScrollContainer) OnFocusMotionRequest (
-	callback func (direction input.KeynavDirection) (granted bool),
-) {
-	element.onFocusMotionRequest = callback
-	element.Propagator.OnFocusMotionRequest(callback)
-}
-
 // CountChildren returns the amount of children contained within this element.
 func (element *ScrollContainer) CountChildren () (count int) {
 	return 3
@@ -199,25 +184,25 @@ func (element *ScrollContainer) redoAll () {
 	if !element.core.HasImage() { return }
 
 	zr := image.Rectangle { }
-	if element.child      != nil { element.child.DrawTo(nil, zr)      }
+	if element.child      != nil { element.child.DrawTo(nil, zr, nil)      }
-	if element.horizontal != nil { element.horizontal.DrawTo(nil, zr) }
+	if element.horizontal != nil { element.horizontal.DrawTo(nil, zr, nil) }
-	if element.vertical   != nil { element.vertical.DrawTo(nil, zr)   }
+	if element.vertical   != nil { element.vertical.DrawTo(nil, zr, nil)   }
 	
 	childBounds, horizontalBounds, verticalBounds := element.layout()
 	if element.child != nil {
 		element.child.DrawTo (
 			canvas.Cut(element.core, childBounds),
-			childBounds)
+			childBounds, element.childDamageCallback)
 	}
 	if element.horizontal != nil {
 		element.horizontal.DrawTo (
 			canvas.Cut(element.core, horizontalBounds),
-			horizontalBounds)
+			horizontalBounds, element.childDamageCallback)
 	}
 	if element.vertical != nil {
 		element.vertical.DrawTo (
 			canvas.Cut(element.core, verticalBounds),
-			verticalBounds)
+			verticalBounds, element.childDamageCallback)
 	}
 	element.draw()
 }
@@ -230,18 +215,8 @@ func (element *ScrollContainer) scrollChildBy (x, y int) {
 	element.child.ScrollTo(scrollPoint)
 }
 
-func (element *ScrollContainer) childFocusRequestCallback (
+func (element *ScrollContainer) childDamageCallback (region image.Rectangle) {
-	child elements.Focusable,
+	element.core.DamageRegion(region)
-) (
-	granted bool,
-) {
-	if element.onFocusRequest != nil && element.onFocusRequest() {
-		element.Propagator.HandleUnfocus()
-		element.Propagator.HandleFocus(input.KeynavDirectionNeutral)
-		return true
-	} else {
-		return false
-	}
 }
 
 func (element *ScrollContainer) layout () (
@@ -308,18 +283,6 @@ func (element *ScrollContainer) updateMinimumSize () {
 	element.core.SetMinimumSize(width, height)
 }
 
-func (element *ScrollContainer) childScrollBoundsChangeCallback () {
-	element.updateEnabled()
-	viewportBounds := element.child.ScrollViewportBounds()
-	contentBounds  := element.child.ScrollContentBounds()
-	if element.horizontal != nil {
-		element.horizontal.SetBounds(contentBounds, viewportBounds)
-	}
-	if element.vertical != nil {
-		element.vertical.SetBounds(contentBounds, viewportBounds)
-	}
-}
-
 func (element *ScrollContainer) updateEnabled () {
 	horizontal, vertical := element.child.ScrollAxes()
 	if element.horizontal != nil {

elements/basic/slider.go

@@ -39,9 +39,9 @@ func NewSlider (value float64, vertical bool) (element *Slider) {
 	} else {
 		element.theme.Case = theme.C("basic", "sliderHorizontal")
 	}
-	element.Core, element.core = core.NewCore(element.draw)
+	element.Core, element.core = core.NewCore(element, element.draw)
 	element.FocusableCore,
-	element.focusableControl = core.NewFocusableCore(element.redo)
+	element.focusableControl = core.NewFocusableCore(element.core, element.redo)
 	element.updateMinimumSize()
 	return
 }

elements/basic/spacer.go

@@ -20,7 +20,7 @@ type Spacer struct {
 func NewSpacer (line bool) (element *Spacer) {
 	element = &Spacer { line: line }
 	element.theme.Case = theme.C("basic", "spacer")
-	element.Core, element.core = core.NewCore(element.draw)
+	element.Core, element.core = core.NewCore(element, element.draw)
 	element.updateMinimumSize()
 	return
 }

elements/basic/switch.go

@@ -33,9 +33,9 @@ func NewSwitch (text string, on bool) (element *Switch) {
 		text: text,
 	}
 	element.theme.Case = theme.C("basic", "switch")
-	element.Core, element.core = core.NewCore(element.draw)
+	element.Core, element.core = core.NewCore(element, element.draw)
 	element.FocusableCore,
-	element.focusableControl = core.NewFocusableCore(element.redo)
+	element.focusableControl = core.NewFocusableCore(element.core, element.redo)
 	element.drawer.SetText([]rune(text))
 	element.updateMinimumSize()
 	return

elements/basic/textbox.go

@@ -6,6 +6,7 @@ import "git.tebibyte.media/sashakoshka/tomo/theme"
 import "git.tebibyte.media/sashakoshka/tomo/config"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
+import "git.tebibyte.media/sashakoshka/tomo/elements"
 import "git.tebibyte.media/sashakoshka/tomo/textdraw"
 import "git.tebibyte.media/sashakoshka/tomo/textmanip"
 import "git.tebibyte.media/sashakoshka/tomo/fixedutil"
@@ -33,7 +34,6 @@ type TextBox struct {
 	
 	onKeyDown func (key input.Key, modifiers input.Modifiers) (handled bool)
 	onChange  func ()
-	onScrollBoundsChange func ()
 }
 
 // NewTextBox creates a new text box with the specified placeholder text, and
@@ -42,9 +42,9 @@ type TextBox struct {
 func NewTextBox (placeholder, value string) (element *TextBox) {
 	element = &TextBox { }
 	element.theme.Case = theme.C("basic", "textBox")
-	element.Core, element.core = core.NewCore(element.handleResize)
+	element.Core, element.core = core.NewCore(element, element.handleResize)
 	element.FocusableCore,
-	element.focusableControl = core.NewFocusableCore (func () {
+	element.focusableControl = core.NewFocusableCore (element.core, func () {
 		if element.core.HasImage () {
 			element.draw()
 			element.core.DamageAll()
@@ -60,8 +60,8 @@ func NewTextBox (placeholder, value string) (element *TextBox) {
 func (element *TextBox) handleResize () {
 	element.scrollToCursor()
 	element.draw()
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 
@@ -187,9 +187,10 @@ func (element *TextBox) HandleKeyDown(key input.Key, modifiers input.Modifiers)
 		element.scrollToCursor()
 	}
 
-	if (textChanged || scrollMemory != element.scroll) &&
+	if (textChanged || scrollMemory != element.scroll) {
-		element.onScrollBoundsChange != nil {
+		if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+			parent.NotifyScrollBoundsChange(element)
+		}
 	}
 	
 	if altered {
@@ -274,8 +275,8 @@ func (element *TextBox) ScrollTo (position image.Point) {
 	if element.scroll > maxPosition { element.scroll = maxPosition }
 
 	element.redo()
-	if element.onScrollBoundsChange != nil {
+	if parent, ok := element.core.Parent().(elements.ScrollableParent); ok {
-		element.onScrollBoundsChange()
+		parent.NotifyScrollBoundsChange(element)
 	}
 }
 
@@ -284,10 +285,6 @@ func (element *TextBox) ScrollAxes () (horizontal, vertical bool) {
 	return true, false
 }
 
-func (element *TextBox) OnScrollBoundsChange (callback func ()) {
-	element.onScrollBoundsChange = callback
-}
-
 func (element *TextBox) runOnChange () {
 	if element.onChange != nil {
 		element.onChange()