119 lines
3.6 KiB
Go
119 lines
3.6 KiB
Go
package core
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import "git.tebibyte.media/sashakoshka/tomo/input"
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// FocusableCore is a struct that can be embedded into objects to make them
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// focusable, giving them the default keynav behavior.
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type FocusableCore struct {
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focused bool
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enabled bool
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drawFocusChange func ()
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onFocusRequest func () (granted bool)
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onFocusMotionRequest func(input.KeynavDirection) (granted bool)
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}
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// NewFocusableCore creates a new focusability core and its corresponding
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// control. If your element needs to visually update itself when it's focus
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// state changes (which it should), a callback to draw and push the update can
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// be specified.
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func NewFocusableCore (
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drawFocusChange func (),
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) (
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core *FocusableCore,
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control FocusableCoreControl,
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) {
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core = &FocusableCore {
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drawFocusChange: drawFocusChange,
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enabled: true,
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}
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control = FocusableCoreControl { core: core }
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return
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}
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// Focused returns whether or not this element is currently focused.
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func (core *FocusableCore) Focused () (focused bool) {
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return core.focused
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}
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// Focus focuses this element, if its parent element grants the request.
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func (core *FocusableCore) Focus () {
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if !core.enabled || core.focused { return }
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if core.onFocusRequest != nil {
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if core.onFocusRequest() {
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core.focused = true
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if core.drawFocusChange != nil {
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core.drawFocusChange()
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}
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}
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}
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}
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// HandleFocus causes this element to mark itself as focused, if it can
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// currently be. Otherwise, it will return false and do nothing.
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func (core *FocusableCore) HandleFocus (
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direction input.KeynavDirection,
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) (
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accepted bool,
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) {
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direction = direction.Canon()
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if !core.enabled { return false }
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if core.focused && direction != input.KeynavDirectionNeutral {
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return false
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}
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if core.focused == false {
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core.focused = true
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if core.drawFocusChange != nil { core.drawFocusChange() }
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}
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return true
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}
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// HandleUnfocus causes this element to mark itself as unfocused.
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func (core *FocusableCore) HandleUnfocus () {
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core.focused = false
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if core.drawFocusChange != nil { core.drawFocusChange() }
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}
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// OnFocusRequest sets a function to be called when this element
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// wants its parent element to focus it. Parent elements should return
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// true if the request was granted, and false if it was not.
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func (core *FocusableCore) OnFocusRequest (callback func () (granted bool)) {
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core.onFocusRequest = callback
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}
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// OnFocusMotionRequest sets a function to be called when this
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// element wants its parent element to focus the element behind or in
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// front of it, depending on the specified direction. Parent elements
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// should return true if the request was granted, and false if it was
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// not.
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func (core *FocusableCore) OnFocusMotionRequest (
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callback func (direction input.KeynavDirection) (granted bool),
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) {
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core.onFocusMotionRequest = callback
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}
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// Enabled returns whether or not the element is enabled.
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func (core *FocusableCore) Enabled () (enabled bool) {
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return core.enabled
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}
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// FocusableCoreControl is a struct that can be used to exert control over a
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// focusability core. It must not be directly embedded into an element, but
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// instead kept as a private member. When a FocusableCore struct is created, a
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// corresponding FocusableCoreControl struct is linked to it and returned
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// alongside it.
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type FocusableCoreControl struct {
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core *FocusableCore
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}
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// SetEnabled sets whether the focusability core is enabled. If the state
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// changes, this will call drawFocusChange.
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func (control FocusableCoreControl) SetEnabled (enabled bool) {
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if control.core.enabled == enabled { return }
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control.core.enabled = enabled
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if !enabled { control.core.focused = false }
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if control.core.drawFocusChange != nil {
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control.core.drawFocusChange()
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}
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}
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