Redid the entity system a bit to make it more reliable

Now it supports things like parenting elements before they are
added to a window and elements no longer have to constantly check
for a nil entity

backend.go

@@ -17,6 +17,9 @@ type Backend interface {
 	// possible. This method must be safe to call from other threads.
 	Do (callback func ())
 
+	// NewEntity creates a new entity for the specified element.
+	NewEntity (owner Element) Entity
+
 	// NewWindow creates a new window within the specified bounding
 	// rectangle. The position on screen may be overridden by the backend or
 	// operating system.

backends/x/entity.go

@@ -19,29 +19,46 @@ type entity struct {
 	isContainer   bool
 }
 
-func bind (parent *entity, window *window, element tomo.Element) *entity {
-	entity := &entity {
-		window:  window,
-		parent:  parent,
-		element: element,
-	}
-	entity.Invalidate()
-	if _, ok := element.(tomo.Container); ok {
+func (backend *Backend) NewEntity (owner tomo.Element) tomo.Entity {
+	entity := &entity { element: owner }
+	if _, ok := owner.(tomo.Container); ok {
 		entity.isContainer = true
 		entity.InvalidateLayout()
 	}
-
-	element.Bind(entity)
 	return entity
 }
 
-func (entity *entity) unbind () {
-	entity.element.Bind(nil)
-	for _, childEntity := range entity.children {
-		childEntity.unbind()
+func (ent *entity) unlink () {
+	ent.propagate (func (child *entity) bool {
+		child.window = nil
+		delete(ent.window.system.drawingInvalid, child)
+		return true
+	})
+	
+	delete(ent.window.system.drawingInvalid, ent)
+	ent.parent = nil
+	ent.window = nil
+}
+
+func (entity *entity) link (parent *entity) {
+	entity.parent = parent
+	if parent.window != nil {
+		entity.setWindow(parent.window)
 	}
 }
 
+func (ent *entity) setWindow (window *window) {
+	ent.window = window
+	ent.Invalidate()
+	ent.InvalidateLayout()
+	ent.propagate (func (child *entity) bool {
+		child.window = window
+		ent.Invalidate()
+		ent.InvalidateLayout()
+		return true
+	})
+}
+
 func (entity *entity) propagate (callback func (*entity) bool) {
 	for _, child := range entity.children {
 		if callback(child) { break }
@@ -61,6 +78,7 @@ func (entity *entity) childAt (point image.Point) *entity {
 // ----------- Entity ----------- //
 
 func (entity *entity) Invalidate () {
+	if entity.window == nil { return }
 	if entity.window.system.invalidateIgnore { return }
 	entity.window.drawingInvalid.Add(entity)
 }
@@ -77,39 +95,54 @@ func (entity *entity) SetMinimumSize (width, height int) {
 	entity.minWidth  = width
 	entity.minHeight = height
 	if entity.parent == nil {
-		entity.window.setMinimumSize(width, height)
+		if entity.window != nil {
+			entity.window.setMinimumSize(width, height)
+		}
 	} else {
 		entity.parent.element.(tomo.Container).
 			HandleChildMinimumSizeChange(entity.element)
 	}
 }
 
-func (entity *entity) DrawBackground (destination canvas.Canvas, bounds image.Rectangle) {
-	if entity.parent == nil { return }
-	entity.parent.element.(tomo.Container).DrawBackground(destination, bounds)
+func (entity *entity) DrawBackground (destination canvas.Canvas) {
+	if entity.parent != nil {
+		entity.parent.element.(tomo.Container).DrawBackground(destination)
+	} else if entity.window != nil {
+		entity.window.system.theme.Pattern (
+			tomo.PatternBackground,
+			tomo.State { }).Draw (
+				destination,
+				entity.window.canvas.Bounds())
+	}
 }
 
 // ----------- ContainerEntity ----------- //
 
 func (entity *entity) InvalidateLayout () {
+	if entity.window == nil { return }
 	if !entity.isContainer { return }
 	entity.layoutInvalid = true
 	entity.window.system.anyLayoutInvalid = true
 }
 
-func (entity *entity) Adopt (child tomo.Element) {
-	entity.children = append(entity.children, bind(entity, entity.window, child))
+func (ent *entity) Adopt (child tomo.Element) {
+	childEntity, ok := child.Entity().(*entity)
+	if !ok || childEntity == nil { return }
+	childEntity.link(ent)
+	ent.children = append(ent.children, childEntity)
 }
 
-func (entity *entity) Insert (index int, child tomo.Element) {
-	entity.children = append (
-		entity.children[:index + 1],
-		entity.children[index:]...)
-	entity.children[index] = bind(entity, entity.window, child)
+func (ent *entity) Insert (index int, child tomo.Element) {
+	childEntity, ok := child.Entity().(*entity)
+	if !ok || childEntity == nil { return }
+	ent.children = append (
+		ent.children[:index + 1],
+		ent.children[index:]...)
+	ent.children[index] = childEntity
 }
 
 func (entity *entity) Disown (index int) {
-	entity.children[index].unbind()
+	entity.children[index].unlink()
 	entity.children = append (
 		entity.children[:index],
 		entity.children[index + 1:]...)
@@ -138,9 +171,7 @@ func (entity *entity) PlaceChild (index int, bounds image.Rectangle) {
 	child.bounds = bounds
 	child.clippedBounds = entity.bounds.Intersect(bounds)
 	child.Invalidate()
-	if child.isContainer {
-		child.InvalidateLayout()
-	}
+	child.InvalidateLayout()
 }
 
 func (entity *entity) ChildMinimumSize (index int) (width, height int) {
@@ -151,10 +182,12 @@ func (entity *entity) ChildMinimumSize (index int) (width, height int) {
 // ----------- FocusableEntity ----------- //
 
 func (entity *entity) Focused () bool {
+	if entity.window == nil { return false }
 	return entity.window.focused == entity
 }
 
 func (entity *entity) Focus () {
+	if entity.window == nil { return }
 	previous := entity.window.focused
 	entity.window.focused = entity
 	if previous != nil {

backends/x/system.go

@@ -3,6 +3,8 @@ package x
 import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
+import "git.tebibyte.media/sashakoshka/tomo/default/theme"
+import "git.tebibyte.media/sashakoshka/tomo/default/config"
 
 type entitySet map[*entity] struct { }
 
@@ -24,8 +26,8 @@ type system struct {
 	focused *entity
 	canvas  canvas.BasicCanvas
 
-	theme  tomo.Theme
-	config tomo.Config
+	theme  theme.Wrapped
+	config config.Wrapped
 
 	invalidateIgnore bool
 	drawingInvalid   entitySet
@@ -41,7 +43,7 @@ func (system *system) initialize () {
 }
 
 func (system *system) SetTheme (theme tomo.Theme) {
-	system.theme = theme
+	system.theme.Theme = theme
 	system.propagate (func (entity *entity) bool {
 		if child, ok := system.child.element.(tomo.Themeable); ok {
 			child.SetTheme(theme)
@@ -51,7 +53,7 @@ func (system *system) SetTheme (theme tomo.Theme) {
 }
 
 func (system *system) SetConfig (config tomo.Config) {
-	system.config = config
+	system.config.Config = config
 	system.propagate (func (entity *entity) bool {
 		if child, ok := system.child.element.(tomo.Configurable); ok {
 			child.SetConfig(config)

backends/x/window.go

@@ -67,6 +67,7 @@ func (backend *Backend) newWindow (
 
 	window.system.initialize()
 	window.system.pushFunc = window.pasteAndPush
+	window.theme.Case = tomo.C("tomo", "window")
 
 	window.xWindow, err = xwindow.Generate(backend.connection)
 	if err != nil { return }
@@ -142,14 +143,18 @@ func (window *window) Window () tomo.Window {
 func (window *window) Adopt (child tomo.Element) {
 	// disown previous child
 	if window.child != nil {
-		window.child.unbind()
+		window.child.unlink()
 		window.child = nil
 	}
 
 	// adopt new child
 	if child != nil {
-		window.child = bind(nil, window, child)
-		window.resizeChildToFit()
+		childEntity, ok := child.Entity().(*entity)
+		if ok && childEntity != nil {
+			window.child = childEntity
+			childEntity.setWindow(window)
+			window.resizeChildToFit()
+		}
 	}
 }
 

element.go

@@ -6,13 +6,13 @@ import "git.tebibyte.media/sashakoshka/tomo/canvas"
 
 // Element represents a basic on-screen object.
 type Element interface {
-	// Bind assigns an Entity to this element.
-	Bind (Entity)
-	
 	// Draw causes the element to draw to the specified canvas. The bounds
 	// of this canvas specify the area that is actually drawn to, while the
 	// Entity bounds specify the actual area of the element.
 	Draw (canvas.Canvas)
+
+	// Entity returns this element's entity.
+	Entity () Entity
 }
 
 // Container is an element capable of containing child elements.
@@ -22,9 +22,11 @@ type Container interface {
 	// Layout causes this element to arrange its children.
 	Layout ()
 
-	// DrawBackground draws this element's background pattern at the
-	// specified bounds to any canvas.
-	DrawBackground (destination canvas.Canvas, bounds image.Rectangle)
+	// DrawBackground causes the element to draw its background pattern to
+	// the specified canvas. The bounds of this canvas specify the area that
+	// is actually drawn to, while the Entity bounds specify the actual area
+	// of the element.
+	DrawBackground (canvas.Canvas)
 
 	// HandleChildMinimumSizeChange is called when a child's minimum size is
 	// changed.

elements/button.go

@@ -30,6 +30,7 @@ type Button struct {
 // NewButton creates a new button with the specified label text.
 func NewButton (text string) (element *Button) {
 	element = &Button { showText: true, enabled: true }
+	element.entity = tomo.NewEntity(element).(tomo.FocusableEntity)
 	element.theme.Case = tomo.C("tomo", "button")
 	element.drawer.SetFace (element.theme.FontFace (
 		tomo.FontStyleRegular,
@@ -38,11 +39,9 @@ func NewButton (text string) (element *Button) {
 	return
 }
 
-// Bind binds this element to an entity.
-func (element *Button) Bind (entity tomo.Entity) {
-	if entity == nil { element.entity = nil; return }
-	element.entity = entity.(tomo.FocusableEntity)
-	element.updateMinimumSize()
+// Entity returns this element's entity.
+func (element *Button) Entity () tomo.Entity {
+	return element.entity
 }
 
 // OnClick sets the function to be called when the button is clicked.
@@ -52,7 +51,6 @@ func (element *Button) OnClick (callback func ()) {
 
 // Focus gives this element input focus.
 func (element *Button) Focus () {
-	if element.entity == nil { return }
 	if !element.entity.Focused() { element.entity.Focus() }
 }
 
@@ -65,7 +63,6 @@ func (element *Button) Enabled () bool {
 func (element *Button) SetEnabled (enabled bool) {
 	if element.enabled == enabled { return }
 	element.enabled = enabled
-	if element.entity == nil { return }
 	element.entity.Invalidate()
 }
 
@@ -74,7 +71,6 @@ func (element *Button) SetText (text string) {
 	if element.text == text { return }
 	element.text = text
 	element.drawer.SetText([]rune(text))
-	if element.entity == nil { return }
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -97,7 +93,6 @@ func (element *Button) SetIcon (id tomo.Icon) {
 func (element *Button) ShowText (showText bool) {
 	if element.showText == showText { return }
 	element.showText = showText
-	if element.entity == nil { return }
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -109,7 +104,6 @@ func (element *Button) SetTheme (new tomo.Theme) {
 	element.drawer.SetFace (element.theme.FontFace (
 		tomo.FontStyleRegular,
 		tomo.FontSizeNormal))
-	if element.entity == nil { return }
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -118,14 +112,12 @@ func (element *Button) SetTheme (new tomo.Theme) {
 func (element *Button) SetConfig (new tomo.Config) {
 	if new == element.config.Config { return }
 	element.config.Config = new
-	if element.entity == nil { return }
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
 
 // Draw causes the element to draw to the specified destination canvas.
 func (element *Button) Draw (destination canvas.Canvas) {
-	if element.entity == nil { return }
 	state   := element.state()
 	bounds  := element.entity.Bounds()
 	pattern := element.theme.Pattern(tomo.PatternButton, state)
@@ -182,7 +174,7 @@ func (element *Button) Draw (destination canvas.Canvas) {
 }
 
 func (element *Button) HandleFocusChange () {
-	if element.entity != nil { element.entity.Invalidate() }
+	element.entity.Invalidate()
 }
 
 func (element *Button) HandleMouseDown (x, y int, button input.Button) {
@@ -190,32 +182,31 @@ func (element *Button) HandleMouseDown (x, y int, button input.Button) {
 	element.Focus()
 	if button != input.ButtonLeft { return }
 	element.pressed = true
-	if element.entity != nil { element.entity.Invalidate() }
+	element.entity.Invalidate()
 }
 
 func (element *Button) HandleMouseUp (x, y int, button input.Button) {
-	if element.entity == nil { return }
 	if button != input.ButtonLeft { return }
 	element.pressed = false
 	within := image.Point { x, y }.In(element.entity.Bounds())
 	if element.Enabled() && within && element.onClick != nil {
 		element.onClick()
 	}
-	if element.entity != nil { element.entity.Invalidate() }
+	element.entity.Invalidate()
 }
 
 func (element *Button) HandleKeyDown (key input.Key, modifiers input.Modifiers) {
 	if !element.Enabled() { return }
 	if key == input.KeyEnter {
 		element.pressed = true
-		if element.entity != nil { element.entity.Invalidate() }
+		element.entity.Invalidate()
 	}
 }
 
 func (element *Button) HandleKeyUp(key input.Key, modifiers input.Modifiers) {
 	if key == input.KeyEnter && element.pressed {
 		element.pressed = false
-	if element.entity != nil { element.entity.Invalidate() }
+		element.entity.Invalidate()
 		if !element.Enabled() { return }
 		if element.onClick != nil {
 			element.onClick()

elements/checkbox.go

@@ -27,6 +27,7 @@ type Checkbox struct {
 // NewCheckbox creates a new cbeckbox with the specified label text.
 func NewCheckbox (text string, checked bool) (element *Checkbox) {
 	element = &Checkbox { checked: checked, enabled: true }
+	element.entity = tomo.NewEntity(element).(tomo.FocusableEntity)
 	element.theme.Case = tomo.C("tomo", "checkbox")
 	element.drawer.SetFace (element.theme.FontFace (
 		tomo.FontStyleRegular,
@@ -35,11 +36,9 @@ func NewCheckbox (text string, checked bool) (element *Checkbox) {
 	return
 }
 
-// Bind binds this element to an entity.
-func (element *Checkbox) Bind (entity tomo.Entity) {
-	if entity == nil { element.entity = nil; return }
-	element.entity = entity.(tomo.FocusableEntity)
-	element.updateMinimumSize()
+// Entity returns this element's entity.
+func (element *Checkbox) Entity () tomo.Entity {
+	return element.entity
 }
 
 // OnToggle sets the function to be called when the checkbox is toggled.
@@ -54,7 +53,6 @@ func (element *Checkbox) Value () (checked bool) {
 
 // Focus gives this element input focus.
 func (element *Checkbox) Focus () {
-	if element.entity == nil { return }
 	if !element.entity.Focused() { element.entity.Focus() }
 }
 
@@ -76,7 +74,6 @@ func (element *Checkbox) SetText (text string) {
 	if element.text == text { return }
 	element.text = text
 	element.drawer.SetText([]rune(text))
-	if element.entity == nil { return }
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -88,7 +85,6 @@ func (element *Checkbox) SetTheme (new tomo.Theme) {
 	element.drawer.SetFace (element.theme.FontFace (
 		tomo.FontStyleRegular,
 		tomo.FontSizeNormal))
-	if element.entity == nil { return }
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -97,15 +93,12 @@ func (element *Checkbox) SetTheme (new tomo.Theme) {
 func (element *Checkbox) SetConfig (new tomo.Config) {
 	if new == element.config.Config { return }
 	element.config.Config = new
-	if element.entity == nil { return }
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
 
 // Draw causes the element to draw to the specified destination canvas.
 func (element *Checkbox) Draw (destination canvas.Canvas) {
-	if element.entity == nil { return }
-	
 	bounds := element.entity.Bounds()
 	boxBounds := image.Rect(0, 0, bounds.Dy(), bounds.Dy()).Add(bounds.Min)
 
@@ -116,7 +109,7 @@ func (element *Checkbox) Draw (destination canvas.Canvas) {
 		On:       element.checked,
 	}
 
-	element.entity.DrawBackground(destination, bounds)
+	element.entity.DrawBackground(destination)
 		
 	pattern := element.theme.Pattern(tomo.PatternButton, state)
 	pattern.Draw(destination, boxBounds)
@@ -135,7 +128,6 @@ func (element *Checkbox) Draw (destination canvas.Canvas) {
 }
 
 func (element *Checkbox) HandleMouseDown (x, y int, button input.Button) {
-	if element.entity == nil { return }
 	if !element.Enabled() { return }
 	element.Focus()
 	element.pressed = true
@@ -143,7 +135,6 @@ func (element *Checkbox) HandleMouseDown (x, y int, button input.Button) {
 }
 
 func (element *Checkbox) HandleMouseUp (x, y int, button input.Button) {
-	if element.entity == nil { return }
 	if button != input.ButtonLeft || !element.pressed { return }
 
 	element.pressed = false
@@ -167,7 +158,6 @@ func (element *Checkbox) HandleKeyDown (key input.Key, modifiers input.Modifiers
 }
 
 func (element *Checkbox) HandleKeyUp (key input.Key, modifiers input.Modifiers) {
-	if element.entity == nil { return }
 	if key == input.KeyEnter && element.pressed {
 		element.pressed = false
 		element.checked = !element.checked

elements/icon.go

@@ -20,15 +20,15 @@ func NewIcon (id tomo.Icon, size tomo.IconSize) (element *Icon) {
 		id:   id,
 		size: size,
 	}
+	element.entity = tomo.NewEntity(element)
 	element.theme.Case = tomo.C("tomo", "icon")
+	element.updateMinimumSize()
 	return
 }
 
-// Bind binds this element to an entity.
-func (element *Icon) Bind (entity tomo.Entity) {
-	if entity == nil { element.entity = nil; return }
-	element.entity = entity
-	element.updateMinimumSize()
+// Entity returns this element's entity.
+func (element *Icon) Entity () tomo.Entity {
+	return element.entity
 }
 
 // SetIcon sets the element's icon.

elements/image.go

@@ -16,15 +16,15 @@ type Image struct {
 // NewImage creates a new image element.
 func NewImage (image image.Image) (element *Image) {
 	element = &Image { buffer: canvas.FromImage(image) }
+	element.entity = tomo.NewEntity(element)
+	bounds := element.buffer.Bounds()
+	element.entity.SetMinimumSize(bounds.Dx(), bounds.Dy())
 	return
 }
 
-// Bind binds this element to an entity.
-func (element *Image) Bind (entity tomo.Entity) {
-	if entity == nil { element.entity = nil; return }
-	element.entity = entity
-	bounds := element.buffer.Bounds()
-	element.entity.SetMinimumSize(bounds.Dx(), bounds.Dy())
+// Entity returns this element's entity.
+func (element *Image) Entity () tomo.Entity {
+	return element.entity
 }
 
 // Draw causes the element to draw to the specified destination canvas.

elements/label.go

@@ -29,6 +29,7 @@ type Label struct {
 func NewLabel (text string, wrap bool) (element *Label) {
 	element = &Label { }
 	element.theme.Case = tomo.C("tomo", "label")
+	element.entity = tomo.NewEntity(element).(tomo.FlexibleEntity)
 	element.drawer.SetFace (element.theme.FontFace (
 		tomo.FontStyleRegular,
 		tomo.FontSizeNormal))
@@ -37,11 +38,9 @@ func NewLabel (text string, wrap bool) (element *Label) {
 	return
 }
 
-// Bind binds this element to an entity.
-func (element *Label) Bind (entity tomo.Entity) {
-	if entity == nil { element.entity = nil; return }
-	element.entity = entity.(tomo.FlexibleEntity)
-	element.updateMinimumSize()
+// Entity returns this element's entity.
+func (element *Label) Entity () tomo.Entity {
+	return element.entity
 }
 
 // EmCollapse forces a minimum width and height upon the label. The width is
@@ -128,14 +127,14 @@ func (element *Label) SetConfig (new tomo.Config) {
 func (element *Label) Draw (destination canvas.Canvas) {
 	if element.entity == nil { return }
 	
-	bounds := element.entity. Bounds()
+	bounds := element.entity.Bounds()
 	
 	if element.wrap {
 		element.drawer.SetMaxWidth(bounds.Dx())
 		element.drawer.SetMaxHeight(bounds.Dy())
 	}
 	
-	element.entity.DrawBackground(destination, bounds)
+	element.entity.DrawBackground(destination)
 
 	textBounds := element.drawer.LayoutBounds()
 	foreground := element.theme.Color (

entity.go

@@ -24,9 +24,11 @@ type Entity interface {
 	SetMinimumSize (width, height int)
 
 	// DrawBackground asks the parent element to draw its background pattern
-	// within the specified rectangle. This should be used for transparent
-	// elements like text labels.
-	DrawBackground (destination canvas.Canvas, bounds image.Rectangle)
+	// to a canvas. This should be used for transparent elements like text
+	// labels. If there is no parent element (that is, the element is
+	// directly inside of the window), the backend will draw a default
+	// background pattern.
+	DrawBackground (canvas.Canvas)
 }
 
 // ContainerEntity is given to elements that support the Container interface.

tomo.go

@@ -29,6 +29,12 @@ func Do (callback func ()) {
 	backend.Do(callback)
 }
 
+// NewEntity generates an entity for an element using the current backend.
+func NewEntity (owner Element) Entity {
+	assertBackend()
+	return backend.NewEntity(owner)
+}
+
 // NewWindow creates a new window using the current backend, and returns it as a
 // MainWindow. If the window could not be created, an error is returned
 // explaining why.