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tomo-old/elements/core/propagator.go
2023-03-31 01:06:29 -04:00

356 lines
11 KiB
Go

package core
import "image"
import "git.tebibyte.media/sashakoshka/tomo"
import "git.tebibyte.media/sashakoshka/tomo/input"
// Container represents an object that can provide access to a list of child
// elements.
type Container interface {
Child (index int) tomo.Element
CountChildren () int
}
// Propagator is a struct that can be embedded into elements that contain one or
// more children in order to propagate events to them without having to write
// all of the event handlers. It also implements standard behavior for focus
// propagation and keyboard navigation.
type Propagator struct {
core CoreControl
container Container
drags [10]tomo.MouseTarget
focused bool
}
// NewPropagator creates a new event propagator that uses the specified
// container to access a list of child elements that will have events propagated
// to them. If container is nil, the function will return nil.
func NewPropagator (container Container, core CoreControl) (propagator *Propagator) {
if container == nil { return nil }
propagator = &Propagator {
core: core,
container: container,
}
return
}
// ----------- Interface fulfillment methods ----------- //
// Focused returns whether or not this element or any of its children
// are currently focused.
func (propagator *Propagator) Focused () (focused bool) {
return propagator.focused
}
// Focus focuses this element, if its parent element grants the
// request.
func (propagator *Propagator) Focus () {
if propagator.focused == true { return }
parent := propagator.core.Parent()
if parent, ok := parent.(tomo.FocusableParent); ok && parent != nil {
propagator.focused = parent.RequestFocus (
propagator.core.Outer().(tomo.Focusable))
}
}
// HandleFocus causes this element to mark itself as focused. If the
// element does not have children or there are no more focusable children in
// the given direction, it should return false and do nothing. Otherwise, it
// marks itself as focused along with any applicable children and returns
// true.
func (propagator *Propagator) HandleFocus (direction input.KeynavDirection) (accepted bool) {
direction = direction.Canon()
firstFocused := propagator.firstFocused()
if firstFocused < 0 {
// no element is currently focused, so we need to focus either
// the first or last focusable element depending on the
// direction.
switch direction {
case input.KeynavDirectionForward:
// if we recieve a forward direction, focus the first
// focusable element.
return propagator.focusFirstFocusableElement(direction)
case input.KeynavDirectionBackward:
// if we recieve a backward direction, focus the last
// focusable element.
return propagator.focusLastFocusableElement(direction)
case input.KeynavDirectionNeutral:
// if we recieve a neutral direction, just focus this
// element and nothing else.
propagator.focused = true
return true
}
} else {
// an element is currently focused, so we need to move the
// focus in the specified direction
firstFocusedChild :=
propagator.container.Child(firstFocused).
(tomo.Focusable)
// before we move the focus, the currently focused child
// may also be able to move its focus. if the child is able
// to do that, we will let it and not move ours.
if firstFocusedChild.HandleFocus(direction) {
return true
}
// find the previous/next focusable element relative to the
// currently focused element, if it exists.
for index := firstFocused + int(direction);
index < propagator.container.CountChildren() && index >= 0;
index += int(direction) {
child, focusable :=
propagator.container.Child(index).
(tomo.Focusable)
if focusable && child.HandleFocus(direction) {
// we have found one, so we now actually move
// the focus.
firstFocusedChild.HandleUnfocus()
propagator.focused = true
return true
}
}
}
return false
}
// RequestFocus notifies the parent that a child element is requesting
// keyboard focus. If the parent grants the request, the method will
// return true and the child element should behave as if a HandleFocus
// call was made.
func (propagator *Propagator) RequestFocus (
child tomo.Focusable,
) (
granted bool,
) {
if parent, ok := propagator.core.Parent().(tomo.FocusableParent); ok {
if parent.RequestFocus(propagator.core.Outer().(tomo.Focusable)) {
propagator.HandleUnfocus()
propagator.focused = true
granted = true
}
}
return
}
// RequestFocusMotion notifies the parent that a child element wants the
// focus to be moved to the next focusable element.
func (propagator *Propagator) RequestFocusNext (child tomo.Focusable) {
if !propagator.focused { return }
if parent, ok := propagator.core.Parent().(tomo.FocusableParent); ok {
parent.RequestFocusNext(propagator.core.Outer().(tomo.Focusable))
}
}
// RequestFocusMotion notifies the parent that a child element wants the
// focus to be moved to the previous focusable element.
func (propagator *Propagator) RequestFocusPrevious (child tomo.Focusable) {
if !propagator.focused { return }
if parent, ok := propagator.core.Parent().(tomo.FocusableParent); ok {
parent.RequestFocusPrevious(propagator.core.Outer().(tomo.Focusable))
}
}
// HandleDeselection causes this element to mark itself and all of its children
// as unfocused.
func (propagator *Propagator) HandleUnfocus () {
propagator.forFocusable (func (child tomo.Focusable) bool {
child.HandleUnfocus()
return true
})
propagator.focused = false
}
// HandleKeyDown propogates the keyboard event to the currently selected child.
func (propagator *Propagator) HandleKeyDown (key input.Key, modifiers input.Modifiers) {
propagator.forFocused (func (child tomo.Focusable) bool {
typedChild, handlesKeyboard := child.(tomo.KeyboardTarget)
if handlesKeyboard {
typedChild.HandleKeyDown(key, modifiers)
}
return true
})
}
// HandleKeyUp propogates the keyboard event to the currently selected child.
func (propagator *Propagator) HandleKeyUp (key input.Key, modifiers input.Modifiers) {
propagator.forFocused (func (child tomo.Focusable) bool {
typedChild, handlesKeyboard := child.(tomo.KeyboardTarget)
if handlesKeyboard {
typedChild.HandleKeyUp(key, modifiers)
}
return true
})
}
// HandleMouseDown propagates the mouse event to the element under the mouse
// pointer.
func (propagator *Propagator) HandleMouseDown (x, y int, button input.Button) {
child, handlesMouse :=
propagator.childAt(image.Pt(x, y)).
(tomo.MouseTarget)
if handlesMouse {
propagator.drags[button] = child
child.HandleMouseDown(x, y, button)
}
}
// HandleMouseUp propagates the mouse event to the element that the released
// mouse button was originally pressed on.
func (propagator *Propagator) HandleMouseUp (x, y int, button input.Button) {
child := propagator.drags[button]
if child != nil {
propagator.drags[button] = nil
child.HandleMouseUp(x, y, button)
}
}
// HandleMotion propagates the mouse event to the element that was last
// pressed down by the mouse if the mouse is currently being held down, else it
// propagates the event to whichever element is underneath the mouse pointer.
func (propagator *Propagator) HandleMotion (x, y int) {
handled := false
for _, child := range propagator.drags {
if child, ok := child.(tomo.MotionTarget); ok {
child.HandleMotion(x, y)
handled = true
}
}
if !handled {
child := propagator.childAt(image.Pt(x, y))
if child, ok := child.(tomo.MotionTarget); ok {
child.HandleMotion(x, y)
}
}
}
// HandleScroll propagates the mouse event to the element under the mouse
// pointer.
func (propagator *Propagator) HandleScroll (x, y int, deltaX, deltaY float64) {
child := propagator.childAt(image.Pt(x, y))
if child, ok := child.(tomo.ScrollTarget); ok {
child.HandleScroll(x, y, deltaX, deltaY)
}
}
// SetTheme sets the theme of all children to the specified theme.
func (propagator *Propagator) SetTheme (theme tomo.Theme) {
propagator.forChildren (func (child tomo.Element) bool {
typedChild, themeable := child.(tomo.Themeable)
if themeable {
typedChild.SetTheme(theme)
}
return true
})
}
// SetConfig sets the theme of all children to the specified config.
func (propagator *Propagator) SetConfig (config tomo.Config) {
propagator.forChildren (func (child tomo.Element) bool {
typedChild, configurable := child.(tomo.Configurable)
if configurable {
typedChild.SetConfig(config)
}
return true
})
}
// ----------- Focusing utilities ----------- //
func (propagator *Propagator) focusFirstFocusableElement (
direction input.KeynavDirection,
) (
ok bool,
) {
propagator.forFocusable (func (child tomo.Focusable) bool {
if child.HandleFocus(direction) {
propagator.focused = true
ok = true
return false
}
return true
})
return
}
func (propagator *Propagator) focusLastFocusableElement (
direction input.KeynavDirection,
) (
ok bool,
) {
propagator.forChildrenReverse (func (child tomo.Element) bool {
typedChild, focusable := child.(tomo.Focusable)
if focusable && typedChild.HandleFocus(direction) {
propagator.focused = true
ok = true
return false
}
return true
})
return
}
// ----------- Iterator utilities ----------- //
func (propagator *Propagator) forChildren (callback func (child tomo.Element) bool) {
for index := 0; index < propagator.container.CountChildren(); index ++ {
child := propagator.container.Child(index)
if child == nil { continue }
if !callback(child) { break }
}
}
func (propagator *Propagator) forChildrenReverse (callback func (child tomo.Element) bool) {
for index := propagator.container.CountChildren() - 1; index > 0; index -- {
child := propagator.container.Child(index)
if child == nil { continue }
if !callback(child) { break }
}
}
func (propagator *Propagator) childAt (position image.Point) (child tomo.Element) {
propagator.forChildren (func (current tomo.Element) bool {
if position.In(current.Bounds()) {
child = current
}
return true
})
return
}
func (propagator *Propagator) forFocused (callback func (child tomo.Focusable) bool) {
propagator.forChildren (func (child tomo.Element) bool {
typedChild, focusable := child.(tomo.Focusable)
if focusable && typedChild.Focused() {
if !callback(typedChild) { return false }
}
return true
})
}
func (propagator *Propagator) forFocusable (callback func (child tomo.Focusable) bool) {
propagator.forChildren (func (child tomo.Element) bool {
typedChild, focusable := child.(tomo.Focusable)
if focusable {
if !callback(typedChild) { return false }
}
return true
})
}
func (propagator *Propagator) firstFocused () int {
for index := 0; index < propagator.container.CountChildren(); index ++ {
child, focusable := propagator.container.Child(index).(tomo.Focusable)
if focusable && child.Focused() {
return index
}
}
return -1
}