action.go

// Copyright 2010 The Walk Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package walk

type actionChangedHandler interface {
	onActionChanged(action *Action) error
	onActionVisibleChanged(action *Action) error
}

var (
	// ISSUE: When pressing enter resp. escape,
	// WM_COMMAND with wParam=1 resp. 2 is sent.
	// Maybe there is more to consider.
	nextActionId    uint16 = 3
	actionsById            = make(map[uint16]*Action)
	shortcut2Action        = make(map[Shortcut]*Action)
)

type Action struct {
	menu                          *Menu
	triggeredPublisher            EventPublisher
	changedHandlers               []actionChangedHandler
	text                          string
	toolTip                       string
	image                         *Bitmap
	enabledCondition              Condition
	enabledConditionChangedHandle int
	visibleCondition              Condition
	visibleConditionChangedHandle int
	refCount                      int
	shortcut                      Shortcut
	enabled                       bool
	visible                       bool
	checkable                     bool
	checked                       bool
	exclusive                     bool
	id                            uint16
}

func NewAction() *Action {
	a := &Action{
		enabled: true,
		id:      nextActionId,
		visible: true,
	}

	actionsById[a.id] = a

	nextActionId++

	return a
}

func NewMenuAction(menu *Menu) *Action {
	a := NewAction()
	a.menu = menu

	return a
}

func NewSeparatorAction() *Action {
	return &Action{
		enabled: true,
		visible: true,
	}
}

func (a *Action) addRef() {
	a.refCount++
}

func (a *Action) release() {
	a.refCount--

	if a.refCount == 0 {
		a.SetEnabledCondition(nil)
		a.SetVisibleCondition(nil)

		if a.menu != nil {
			a.menu.actions.Clear()
		}

		delete(actionsById, a.id)
		delete(shortcut2Action, a.shortcut)
	}
}

func (a *Action) Checkable() bool {
	return a.checkable
}

func (a *Action) SetCheckable(value bool) (err error) {
	if value != a.checkable {
		old := a.checkable

		a.checkable = value

		if err = a.raiseChanged(); err != nil {
			a.checkable = old
			a.raiseChanged()
		}
	}

	return
}

func (a *Action) Checked() bool {
	return a.checked
}

func (a *Action) SetChecked(value bool) (err error) {
	if value != a.checked {
		old := a.checked

		a.checked = value

		if err = a.raiseChanged(); err != nil {
			a.checked = old
			a.raiseChanged()
		}
	}

	return
}

func (a *Action) Enabled() bool {
	if a.enabledCondition != nil {
		return a.enabledCondition.Satisfied()
	}

	return a.enabled
}

func (a *Action) SetEnabled(value bool) (err error) {
	if a.enabledCondition != nil {
		return newError("EnabledCondition != nil")
	}

	if value != a.enabled {
		old := a.enabled

		a.enabled = value

		if err = a.raiseChanged(); err != nil {
			a.enabled = old
			a.raiseChanged()
		}
	}

	return
}

func (a *Action) EnabledCondition() Condition {
	return a.enabledCondition
}

func (a *Action) SetEnabledCondition(c Condition) {
	if a.enabledCondition != nil {
		a.enabledCondition.Changed().Detach(a.enabledConditionChangedHandle)
	}

	a.enabledCondition = c

	if c != nil {
		a.enabled = c.Satisfied()

		a.enabledConditionChangedHandle = c.Changed().Attach(func() {
			if a.enabled != c.Satisfied() {
				a.enabled = !a.enabled

				a.raiseChanged()
			}
		})
	}
}

func (a *Action) Exclusive() bool {
	return a.exclusive
}

func (a *Action) SetExclusive(value bool) (err error) {
	if value != a.exclusive {
		old := a.exclusive

		a.exclusive = value

		if err = a.raiseChanged(); err != nil {
			a.exclusive = old
			a.raiseChanged()
		}
	}

	return
}

func (a *Action) Image() *Bitmap {
	return a.image
}

func (a *Action) SetImage(value *Bitmap) (err error) {
	if value != a.image {
		old := a.image

		a.image = value

		if err = a.raiseChanged(); err != nil {
			a.image = old
			a.raiseChanged()
		}
	}

	return
}

func (a *Action) Shortcut() Shortcut {
	return a.shortcut
}

func (a *Action) SetShortcut(shortcut Shortcut) (err error) {
	if shortcut != a.shortcut {
		old := a.shortcut

		a.shortcut = shortcut
		defer func() {
			if err != nil {
				a.shortcut = old
			}
		}()

		if err = a.raiseChanged(); err != nil {
			a.shortcut = old
			a.raiseChanged()
		} else {
			if shortcut.Key == 0 {
				delete(shortcut2Action, old)
			} else {
				shortcut2Action[shortcut] = a
			}
		}
	}

	return
}

func (a *Action) Text() string {
	return a.text
}

func (a *Action) SetText(value string) (err error) {
	if value != a.text {
		old := a.text

		a.text = value

		if err = a.raiseChanged(); err != nil {
			a.text = old
			a.raiseChanged()
		}
	}

	return
}

func (a *Action) IsSeparator() bool {
	return a.id == 0 || a.text == "-"
}

func (a *Action) ToolTip() string {
	return a.toolTip
}

func (a *Action) SetToolTip(value string) (err error) {
	if value != a.toolTip {
		old := a.toolTip

		a.toolTip = value

		if err = a.raiseChanged(); err != nil {
			a.toolTip = old
			a.raiseChanged()
		}
	}

	return
}

func (a *Action) Visible() bool {
	if a.visibleCondition != nil {
		return a.visibleCondition.Satisfied()
	}

	return a.visible
}

func (a *Action) SetVisible(value bool) (err error) {
	if a.visibleCondition != nil {
		return newError("VisibleCondition != nil")
	}

	if value != a.visible {
		old := a.visible

		a.visible = value

		if err = a.raiseVisibleChanged(); err != nil {
			a.visible = old
			a.raiseVisibleChanged()
		}
	}

	return
}

func (a *Action) VisibleCondition() Condition {
	return a.visibleCondition
}

func (a *Action) SetVisibleCondition(c Condition) {
	if a.visibleCondition != nil {
		a.visibleCondition.Changed().Detach(a.visibleConditionChangedHandle)
	}

	a.visibleCondition = c

	if c != nil {
		a.visible = c.Satisfied()

		a.visibleConditionChangedHandle = c.Changed().Attach(func() {
			if a.visible != c.Satisfied() {
				a.visible = !a.visible

				a.raiseVisibleChanged()
			}
		})
	}
}

func (a *Action) Triggered() *Event {
	return a.triggeredPublisher.Event()
}

func (a *Action) raiseTriggered() {
	a.triggeredPublisher.Publish()
}

func (a *Action) addChangedHandler(handler actionChangedHandler) {
	a.changedHandlers = append(a.changedHandlers, handler)
}

func (a *Action) removeChangedHandler(handler actionChangedHandler) {
	for i, h := range a.changedHandlers {
		if h == handler {
			a.changedHandlers = append(a.changedHandlers[:i], a.changedHandlers[i+1:]...)
			break
		}
	}
}

func (a *Action) raiseChanged() error {
	for _, handler := range a.changedHandlers {
		if err := handler.onActionChanged(a); err != nil {
			return err
		}
	}

	return nil
}

func (a *Action) raiseVisibleChanged() error {
	for _, handler := range a.changedHandlers {
		if err := handler.onActionVisibleChanged(a); err != nil {
			return err
		}
	}

	return nil
}