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