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tomo-old/elements/core/propagator.go

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package core
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/elements"
// ChildIterator represents an object that can iterate over a list of children,
// calling a specified iterator function for each one. When keepGoing is false,
// the iterator stops the current loop and OverChildren returns.
type ChildIterator interface {
OverChildren (func (child elements.Element) (keepGoing bool))
}
// 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 {
iterator ChildIterator
drags [10]elements.MouseTarget
focused bool
}
// NewPropagator creates a new event propagator that uses the specified iterator
// to access a list of child elements that will have events propagated to them.
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// If iterator is nil, the function will return nil.
func NewPropagator (iterator ChildIterator) (propagator *Propagator) {
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if iterator == nil { return nil }
propagator = &Propagator {
iterator: iterator,
}
return
}
// ----------- Interface fulfillment methods ----------- //
// Focused returns whether or not this element or any of its children
// are currently focused.
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func (propagator *Propagator) Focused () (focused bool) {
return propagator.focused
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}
// Focus focuses this element, if its parent element grants the
// request.
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func (propagator *Propagator) Focus () {
// TODO
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}
// HandleFocus causes this element to mark itself as focused. If the
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// 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) {
// TODO
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}
// HandleDeselection causes this element to mark itself and all of its children
// as unfocused.
func (propagator *Propagator) HandleUnfocus () {
// TODO
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}
// OnFocusRequest sets a function to be called when this element wants its
// parent element to focus it. Parent elements should return true if the request
// was granted, and false if it was not. If the parent element returns true, the
// element acts as if a HandleFocus call was made with KeynavDirectionNeutral.
func (propagator *Propagator) OnFocusRequest (func () (granted bool)) {
// TODO
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}
// OnFocusMotionRequest sets a function to be called when this element wants its
// parent element to focus the element behind or in front of it, depending on
// the specified direction. Parent elements should return true if the request
// was granted, and false if it was not.
func (propagator *Propagator) OnFocusMotionRequest (func (direction input.KeynavDirection) (granted bool)) {
// TODO
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}
// HandleKeyDown propogates the keyboard event to the currently selected child.
func (propagator *Propagator) HandleKeyDown (key input.Key, modifiers input.Modifiers) {
propagator.forFocused (func (child elements.Focusable) bool {
typedChild, handlesKeyboard := child.(elements.KeyboardTarget)
if handlesKeyboard {
typedChild.HandleKeyDown(key, modifiers)
}
return true
})
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}
// HandleKeyUp propogates the keyboard event to the currently selected child.
func (propagator *Propagator) HandleKeyUp (key input.Key, modifiers input.Modifiers) {
propagator.forFocused (func (child elements.Focusable) bool {
typedChild, handlesKeyboard := child.(elements.KeyboardTarget)
if handlesKeyboard {
typedChild.HandleKeyUp(key, modifiers)
}
return true
})
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}
// 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)).
(elements.MouseTarget)
if handlesMouse {
propagator.drags[button] = child
child.HandleMouseDown(x, y, button)
}
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}
// 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)
}
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}
// HandleMouseMove 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) HandleMouseMove (x, y int) {
handled := false
for _, child := range propagator.drags {
if child != nil {
child.HandleMouseMove(x, y)
handled = true
}
}
if handled {
child, handlesMouse :=
propagator.childAt(image.Pt(x, y)).
(elements.MouseTarget)
if handlesMouse {
child.HandleMouseMove(x, y)
}
}
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}
// HandleScroll propagates the mouse event to the element under the mouse
// pointer.
func (propagator *Propagator) HandleMouseScroll (x, y int, deltaX, deltaY float64) {
child, handlesMouse :=
propagator.childAt(image.Pt(x, y)).
(elements.MouseTarget)
if handlesMouse {
child.HandleMouseScroll(x, y, deltaX, deltaY)
}
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}
// SetTheme sets the theme of all children to the specified theme.
func (propagator *Propagator) SetTheme (theme theme.Theme) {
propagator.iterator.OverChildren (func (child elements.Element) bool {
typedChild, themeable := child.(elements.Themeable)
if themeable {
typedChild.SetTheme(theme)
}
return true
})
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}
// SetConfig sets the theme of all children to the specified config.
func (propagator *Propagator) SetConfig (config config.Config) {
propagator.iterator.OverChildren (func (child elements.Element) bool {
typedChild, configurable := child.(elements.Configurable)
if configurable {
typedChild.SetConfig(config)
}
return true
})
}
// ----------- Iterator utilities ----------- //
func (propagator *Propagator) childAt (position image.Point) (child elements.Element) {
propagator.iterator.OverChildren (func (current elements.Element) bool {
if position.In(current.Bounds()) {
child = current
}
return true
})
return
}
func (propagator *Propagator) forFocused (callback func (child elements.Focusable) bool) {
propagator.iterator.OverChildren (func (child elements.Element) bool {
typedChild, focusable := child.(elements.Focusable)
if focusable && typedChild.Focused() {
if !callback(typedChild) { return false }
}
return true
})
}
func (propagator *Propagator) forFocusable (callback func (child elements.Focusable) bool) {
propagator.iterator.OverChildren (func (child elements.Element) bool {
typedChild, focusable := child.(elements.Focusable)
if focusable {
if !callback(typedChild) { return false }
}
return true
})
}
func (propagator *Propagator) forFlexible (callback func (child elements.Flexible) bool) {
propagator.iterator.OverChildren (func (child elements.Element) bool {
typedChild, flexible := child.(elements.Flexible)
if flexible {
if !callback(typedChild) { return false }
}
return true
})
}
// func (propagator *Propagator) forFocusableBackward (callback func (child elements.Focusable) bool) {
// for index := len(element.children) - 1; index >= 0; index -- {
// child, focusable := element.children[index].Element.(elements.Focusable)
// if focusable {
// if !callback(child) { break }
// }
// }
// }
func (propagator *Propagator) firstFocused () (index int) {
index = -1
currentIndex := 0
propagator.forFocusable (func (child elements.Focusable) bool {
if child.Focused() {
index = currentIndex
return false
}
currentIndex ++
return true
})
return
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}