backends/x/entity.go

@@ -0,0 +1,154 @@
+package x
+
+import "image"
+import "git.tebibyte.media/sashakoshka/tomo"
+import "git.tebibyte.media/sashakoshka/tomo/canvas"
+
+type entity struct {
+	window      *window
+	parent      *entity
+	children    []*entity
+	element     tomo.Element
+	
+	drawDirty   bool
+	layoutDirty bool
+	
+	bounds      image.Rectangle
+	minWidth    int
+	minHeight   int
+}
+
+func bind (element tomo.Element) *entity {
+	entity := &entity { drawDirty: true }
+	if _, ok := element.(tomo.Container); ok {
+		entity.layoutDirty = true
+	}
+
+	element.Bind(entity)
+	return entity
+}
+
+func (entity *entity) unbind () {
+	entity.element.Bind(nil)
+	for _, childEntity := range entity.children {
+		childEntity.unbind()
+	}
+}
+
+// ----------- Entity ----------- //
+
+func (entity *entity) Invalidate () {
+	entity.drawDirty = true
+}
+
+func (entity *entity) Bounds () image.Rectangle {
+	return entity.bounds
+}
+
+func (entity *entity) Window () tomo.Window {
+	return entity.window
+}
+
+func (entity *entity) SetMinimumSize (width, height int) {
+	entity.minWidth  = width
+	entity.minHeight = height
+	if entity.parent == nil { return }
+	entity.parent.element.(tomo.Container).HandleChildMinimumSizeChange()
+}
+
+func (entity *entity) DrawBackground (destination canvas.Canvas, bounds image.Rectangle) {
+	if entity.parent == nil { return }
+	entity.parent.element.(tomo.Container).DrawBackground(destination, bounds)
+}
+
+// ----------- ContainerEntity ----------- //
+
+func (entity *entity) InvalidateLayout () {
+	entity.layoutDirty = true
+}
+
+func (entity *entity) Adopt (child tomo.Element) {
+	entity.children = append(entity.children, bind(child))
+}
+
+func (entity *entity) Insert (index int, child tomo.Element) {
+	entity.children = append (
+		entity.children[:index + 1],
+		entity.children[index:]...)
+	entity.children[index] = bind(child)
+}
+
+func (entity *entity) Disown (index int) {
+	entity.children[index].unbind()
+	entity.children = append (
+		entity.children[:index],
+		entity.children[index + 1:]...)
+}
+
+func (entity *entity) IndexOf (child tomo.Element) int {
+	for index, childEntity := range entity.children {
+		if childEntity.element == child {
+			return index
+		}
+	}
+
+	return -1
+}
+
+func (entity *entity) Child (index int) tomo.Element {
+	return entity.children[index].element
+}
+
+func (entity *entity) CountChildren () int {
+	return len(entity.children)
+}
+
+func (entity *entity) PlaceChild (index int, bounds image.Rectangle) {
+	entity.children[index].bounds = bounds
+}
+
+func (entity *entity) ChildMinimumSize (index int) (width, height int) {
+	childEntity := entity.children[index]
+	return childEntity.minWidth, childEntity.minHeight
+}
+
+// ----------- FocusableEntity ----------- //
+
+func (entity *entity) Focused () bool {
+	return entity.window.focused == entity
+}
+
+func (entity *entity) Focus () {
+	previous := entity.window.focused
+	entity.window.focused = entity
+	if previous != nil {
+		previous.element.(tomo.Focusable).HandleFocusChange()
+	}
+	entity.element.(tomo.Focusable).HandleFocusChange()
+}
+
+func (entity *entity) FocusNext () {
+	// TODO
+}
+
+func (entity *entity) FocusPrevious () {
+	// TODO
+}
+
+// ----------- FlexibleEntity ----------- //
+
+func (entity *entity) NotifyFlexibleHeightChange () {
+	if entity.parent == nil { return }
+	if parent, ok := entity.parent.element.(tomo.FlexibleContainer); ok {
+		parent.HandleChildFlexibleHeightChange()
+	}
+}
+
+// ----------- ScrollableEntity ----------- //
+
+func (entity *entity) NotifyScrollBoundsChange () {
+	if entity.parent == nil { return }
+	if parent, ok := entity.parent.element.(tomo.ScrollableContainer); ok {
+		parent.HandleChildScrollBoundsChange()
+	}
+}

backends/x/window.go

@@ -24,9 +24,9 @@ type window struct {
 	xWindow *xwindow.Window
 	xCanvas *xgraphics.Image
 	canvas  canvas.BasicCanvas
-	child   tomo.Element
+	child   *entity
+	focused *entity
 	onClose func ()
-	skipChildDrawCallback bool
 
 	title, application string
 

element.go

@@ -25,6 +25,10 @@ type Container interface {
 	// DrawBackground draws this element's background pattern at the
 	// specified bounds to any canvas.
 	DrawBackground (destination canvas.Canvas, bounds image.Rectangle)
+
+	// HandleChildMinimumSizeChange is called when a child's minimum size is
+	// changed.
+	HandleChildMinimumSizeChange ()
 }
 
 // Focusable represents an element that has keyboard navigation support.
@@ -104,6 +108,16 @@ type Flexible interface {
 	FlexibleHeightFor (width int) int
 }
 
+// FlexibleContainer represents an element that is capable of containing
+// flexible children.
+type FlexibleContainer interface {
+	Container
+
+	// HandleChildFlexibleHeightChange is called when the parameters
+	// affecting a child's flexible height are changed.
+	HandleChildFlexibleHeightChange ()
+}
+
 // Scrollable represents an element that can be scrolled. It acts as a viewport
 // through which its contents can be observed.
 type Scrollable interface {
@@ -124,6 +138,16 @@ type Scrollable interface {
 	ScrollAxes () (horizontal, vertical bool)
 }
 
+// ScrollableContainer represents an element that is capable of containing
+// scrollable children.
+type ScrollableContainer interface {
+	Container
+
+	// HandleChildScrollBoundsChange is called when the content bounds,
+	// viewport bounds, or scroll axes of a child are changed.
+	HandleChildScrollBoundsChange()
+}
+
 // Collapsible represents an element who's minimum width and height can be
 // manually resized. Scrollable elements should implement this if possible.
 type Collapsible interface {

entity.go

@@ -1,6 +1,7 @@
 package tomo
 
 import "image"
+import "git.tebibyte.media/sashakoshka/tomo/canvas"
 
 // Entity is a handle given to elements by the backend. Different types of
 // entities may be assigned to elements that support different capabilities.
@@ -25,13 +26,18 @@ type Entity interface {
 	// 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 (bounds image.Rectangle)
+	DrawBackground (destination canvas.Canvas, bounds image.Rectangle)
 }
 
 // ContainerEntity is given to elements that support the Container interface.
 type ContainerEntity interface {
 	Entity
 
+	// InvalidateLayout marks the element's layout as invalid. At the end of
+	// every event, the backend will ask all invalid containers to
+	// recalculate their layouts.
+	InvalidateLayout ()
+
 	// Adopt adds an element as a child.
 	Adopt (child Element)