# ContextualBalloon
class
Provides the common contextual balloon for the editor.
The role of this plugin is to unify the contextual balloons logic, simplify views management and help avoid the unnecessary complexity of handling multiple [`BalloonPanelView`](module_ui_panel_balloon_balloonpanelview-BalloonPanelView.md) instances in the editor.
This plugin allows for creating single or multiple panel stacks.
Each stack may have multiple views, with the one on the top being visible. When the visible view is removed from the stack, the previous view becomes visible.
It might be useful to implement nested navigation in a balloon. For instance, a toolbar view may contain a link button. When you click it, a link view (which lets you set the URL) is created and put on top of the toolbar view, so the link panel is displayed. When you finish editing the link and close (remove) the link view, the toolbar view is visible again.
However, there are cases when there are multiple independent balloons to be displayed, for instance, if the selection is inside two inline comments at the same time. For such cases, you can create two independent panel stacks. The contextual balloon plugin will create a navigation bar to let the users switch between these panel stacks using the "Next" and "Previous" buttons.
If there are no views in the current stack, the balloon panel will try to switch to the next stack. If there are no panels in any stack, the balloon panel will be hidden.
**Note**: To force the balloon panel to show only one view, even if there are other stacks, use the `singleViewMode=true` option when [adding](#function-add) a view to a panel.
From the implementation point of view, the contextual ballon plugin is reusing a single [`BalloonPanelView`](module_ui_panel_balloon_balloonpanelview-BalloonPanelView.md) instance to display multiple contextual balloon panels in the editor. It also creates a special [rotator view](module_ui_panel_balloon_contextualballoon-RotatorView.md), used to manage multiple panel stacks. Rotator view is a child of the balloon panel view and the parent of the specific view you want to display. If there is more than one panel stack to be displayed, the rotator view will add a navigation bar. If there is only one stack, the rotator view is transparent (it does not add any UI elements).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L65)
## Properties
### `_visibleStack: Stack` _(readonly)_
Returns the stack of the currently visible view.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L404)
### `editor: Editor` _(readonly)_
The editor instance.
Note that most editors implement the [`ui`](module_core_editor_editor-Editor.md#member-ui) property. However, editors with an external UI (i.e. Bootstrap-based) or a headless editor may not have this property or throw an error when accessing it.
Because of above, to make plugins more universal, it is recommended to split features into:
* The "editing" part that uses the [`Editor`](module_core_editor_editor-Editor.md) class without `ui` property.
* The "UI" part that uses the [`Editor`](module_core_editor_editor-Editor.md) class and accesses `ui` property.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/plugin.ts#L33)
### `isEnabled: boolean` _(readonly)_
Flag indicating whether a plugin is enabled or disabled. A disabled plugin will not transform text.
Plugin can be simply disabled like that:
```typescript
// Disable the plugin so that no toolbars are visible.
editor.plugins.get( 'TextTransformation' ).isEnabled = false;
```
You can also use [`forceDisabled`](#function-forceDisabled) method.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/plugin.ts#L51)
### `positionLimiter: RectSource | () => ( RectSource | null ) | null | undefined`
The [position limiter](module_utils_dom_position-DomOptimalPositionOptions.md#member-limiter) for the [balloon](#member-view), used when no `limiter` has been passed into [`add`](#function-add) or [`updatePosition`](#function-updatePosition).
By default, a function that obtains the farthest DOM [`ViewRootEditableElement`](module_engine_view_rooteditableelement-ViewRootEditableElement.md) of the [`selection`](module_engine_view_document-ViewDocument.md#member-selection).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L75)
### `view: BalloonPanelView` _(readonly)_
The common balloon panel view.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L192)
### `visibleStack?: string`
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L77)
### `visibleView: View | null` _(readonly)_
The currently visible view or `null` when there are no views in any stack.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L85)
### `_fakePanelsView: FakePanelsView | null` _(private)_
Displays fake panels under the balloon panel view when multiple stacks are added to the balloon.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L129)
### `_idToStack: Map` _(private)_
The map of IDs and stacks.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L113)
### `_numberOfStacks: number` _(private)_
A total number of all stacks in the balloon.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L94)
### `_rotatorView: RotatorView | null` _(private)_
Rotator view embedded in the contextual balloon. Displays the currently visible view in the balloon and provides navigation for switching stacks.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L124)
### `_singleViewMode: boolean` _(private)_
A flag that controls the single view mode.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L103)
### `_view: BalloonPanelView | null` _(private)_
The common balloon panel view.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L118)
### `_viewToStack: Map, Stack>` _(private)_
The map of views and their stacks.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L108)
#### Static properties
### `isContextPlugin: false` _(readonly)_
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/plugin.ts#L144)
### `pluginName: 'ContextualBalloon'` _(readonly)_
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L134)
### `isOfficialPlugin: true` _(internal)_
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L141)
### `isPremiumPlugin: boolean` _(internal)_
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/plugin.ts#L160)
## Methods
### `constructor( editor )`
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L148)
#### Parameters
* `editor: Editor`
### `add( data ) → void`
Adds a new view to the stack and makes it visible if the current stack is visible or it is the first view in the balloon.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L219)
#### Parameters
* `data: ViewConfiguration`
The configuration of the view.
#### Returns
* `void`
### `bind( bindProperty1, bindProperty2 ) → ObservableDualBindChain` _(inherited)_
Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface.
Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples.
Consider two objects: a `button` and an associated `command` (both `Observable`).
A simple property binding could be as follows:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```typescript
button.bind( 'isEnabled' ).to( command );
```
which works in the following way:
* `button.isEnabled` **instantly equals** `command.isEnabled`,
* whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value.
**Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind).
You can also "rename" the property in the binding by specifying the new name in the `to()` chain:
```typescript
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```typescript
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```typescript
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```
The binding can include more than one observable, combining multiple data sources in a custom callback:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```
Using a custom callback allows processing the value before passing it to the target property:
```typescript
button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
```
It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code:
```typescript
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L996)
#### Type parameters
* * `K1`
* `K2`
#### Parameters
* `bindProperty1: K1`
Observable property that will be bound to other observable(s).
* `bindProperty2: K2`
Observable property that will be bound to other observable(s).
#### Returns
* `ObservableDualBindChain`
The bind chain with the `to()` and `toMany()` methods.
### `bind( bindProperties ) → ObservableMultiBindChain` _(inherited)_
Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface.
Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples.
Consider two objects: a `button` and an associated `command` (both `Observable`).
A simple property binding could be as follows:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```typescript
button.bind( 'isEnabled' ).to( command );
```
which works in the following way:
* `button.isEnabled` **instantly equals** `command.isEnabled`,
* whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value.
**Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind).
You can also "rename" the property in the binding by specifying the new name in the `to()` chain:
```typescript
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```typescript
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```typescript
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```
The binding can include more than one observable, combining multiple data sources in a custom callback:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```
Using a custom callback allows processing the value before passing it to the target property:
```typescript
button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
```
It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code:
```typescript
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1074)
#### Parameters
* `bindProperties: Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'view' | 'destroy' | 'remove' | 'add' | 'positionLimiter' | 'visibleStack' | 'visibleView' | '_numberOfStacks' | '_singleViewMode' | 'editor' | 'isEnabled' | 'forceDisabled' | 'clearForceDisabled' | 'updatePosition' | 'getPositionOptions' | 'hasView' | 'showStack'>`
Observable properties that will be bound to other observable(s).
#### Returns
* `ObservableMultiBindChain`
The bind chain with the `to()` and `toMany()` methods.
### `bind( bindProperty ) → ObservableSingleBindChain` _(inherited)_
Binds [observable properties](#function-set:KEY_VALUE) to other objects implementing the [`Observable`](module_utils_observablemixin-Observable.md) interface.
Read more in the [dedicated](../framework/deep-dive/observables.md#property-bindings) guide covering the topic of property bindings with some additional examples.
Consider two objects: a `button` and an associated `command` (both `Observable`).
A simple property binding could be as follows:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```typescript
button.bind( 'isEnabled' ).to( command );
```
which works in the following way:
* `button.isEnabled` **instantly equals** `command.isEnabled`,
* whenever `command.isEnabled` changes, `button.isEnabled` will immediately reflect its value.
**Note**: To release the binding, use [`unbind`](module_utils_observablemixin-Observable.md#function-unbind).
You can also "rename" the property in the binding by specifying the new name in the `to()` chain:
```typescript
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```typescript
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```typescript
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```
The binding can include more than one observable, combining multiple data sources in a custom callback:
```typescript
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```
Using a custom callback allows processing the value before passing it to the target property:
```typescript
button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );
```
It is also possible to bind to the same property in an array of observables. To bind a `button` to multiple commands (also `Observables`) so that each and every one of them must be enabled for the button to become enabled, use the following code:
```typescript
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L918)
#### Type parameters
* `K`
#### Parameters
* `bindProperty: K`
Observable property that will be bound to other observable(s).
#### Returns
* `ObservableSingleBindChain`
The bind chain with the `to()` and `toMany()` methods.
### `clearForceDisabled( id ) → void` _(inherited)_
Clears forced disable previously set through [`forceDisabled`](#function-forceDisabled). See [`forceDisabled`](#function-forceDisabled).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/plugin.ts#L125)
#### Parameters
* `id: string`
Unique identifier, equal to the one passed in [`forceDisabled`](#function-forceDisabled) call.
#### Returns
* `void`
### `decorate( methodName ) → void` _(inherited)_
Turns the given methods of this object into event-based ones. This means that the new method will fire an event (named after the method) and the original action will be plugged as a listener to that event.
Read more in the [dedicated](../framework/deep-dive/observables.md#decorating-object-methods) guide covering the topic of decorating methods with some additional examples.
Decorating the method does not change its behavior (it only adds an event), but it allows to modify it later on by listening to the method's event.
For example, to cancel the method execution the event can be [stopped](module_utils_eventinfo-EventInfo.md#member-stop):
```typescript
class Foo extends ObservableMixin() {
constructor() {
super();
this.decorate( 'method' );
}
method() {
console.log( 'called!' );
}
}
const foo = new Foo();
foo.on( 'method', ( evt ) => {
evt.stop();
}, { priority: 'high' } );
foo.method(); // Nothing is logged.
```
**Note**: The high [priority](module_utils_priorities-PriorityString.md) listener has been used to execute this particular callback before the one which calls the original method (which uses the "normal" priority).
It is also possible to change the returned value:
```typescript
foo.on( 'method', ( evt ) => {
evt.return = 'Foo!';
} );
foo.method(); // -> 'Foo'
```
Finally, it is possible to access and modify the arguments the method is called with:
```typescript
method( a, b ) {
console.log( `${ a }, ${ b }` );
}
// ...
foo.on( 'method', ( evt, args ) => {
args[ 0 ] = 3;
console.log( args[ 1 ] ); // -> 2
}, { priority: 'high' } );
foo.method( 1, 2 ); // -> '3, 2'
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1159)
#### Parameters
* `methodName: 'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'view' | 'destroy' | 'remove' | 'add' | 'positionLimiter' | 'visibleStack' | 'visibleView' | '_numberOfStacks' | '_singleViewMode' | 'editor' | 'isEnabled' | 'forceDisabled' | 'clearForceDisabled' | 'updatePosition' | 'getPositionOptions' | 'hasView' | 'showStack'`
Name of the method to decorate.
#### Returns
* `void`
### `delegate( events ) → EmitterMixinDelegateChain` _(inherited)_
Delegates selected events to another [`Emitter`](module_utils_emittermixin-Emitter.md). For instance:
```typescript
emitterA.delegate( 'eventX' ).to( emitterB );
emitterA.delegate( 'eventX', 'eventY' ).to( emitterC );
```
then `eventX` is delegated (fired by) `emitterB` and `emitterC` along with `data`:
```typescript
emitterA.fire( 'eventX', data );
```
and `eventY` is delegated (fired by) `emitterC` along with `data`:
```typescript
emitterA.fire( 'eventY', data );
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L539)
#### Parameters
* `events: Array`
Event names that will be delegated to another emitter.
#### Returns
* `EmitterMixinDelegateChain`
### `destroy() → void`
Destroys the plugin.
**Note:** This method is optional. A plugin instance does not need to have it defined.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L173)
#### Returns
* `void`
### `fire( eventOrInfo, args ) → GetEventInfo[ 'return' ]` _(inherited)_
Fires an event, executing all callbacks registered for it.
The first parameter passed to callbacks is an [`EventInfo`](module_utils_eventinfo-EventInfo.md) object, followed by the optional `args` provided in the `fire()` method call.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L512)
#### Type parameters
* `TEvent: extends BaseEvent`
The type describing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).
#### Parameters
* `eventOrInfo: GetNameOrEventInfo`
The name of the event or `EventInfo` object if event is delegated.
* `args: TEvent[ 'args' ]`
Additional arguments to be passed to the callbacks.
#### Returns
* `GetEventInfo[ 'return' ]`
By default the method returns `undefined`. However, the return value can be changed by listeners through modification of the [`evt.return`](module_utils_eventinfo-EventInfo.md#member-return)'s property (the event info is the first param of every callback).
### `forceDisabled( id ) → void` _(inherited)_
Disables the plugin.
Plugin may be disabled by multiple features or algorithms (at once). When disabling a plugin, unique id should be passed (e.g. feature name). The same identifier should be used when [enabling back](#function-clearForceDisabled) the plugin. The plugin becomes enabled only after all features [enabled it back](#function-clearForceDisabled).
Disabling and enabling a plugin:
```typescript
plugin.isEnabled; // -> true
plugin.forceDisabled( 'MyFeature' );
plugin.isEnabled; // -> false
plugin.clearForceDisabled( 'MyFeature' );
plugin.isEnabled; // -> true
```
Plugin disabled by multiple features:
```typescript
plugin.forceDisabled( 'MyFeature' );
plugin.forceDisabled( 'OtherFeature' );
plugin.clearForceDisabled( 'MyFeature' );
plugin.isEnabled; // -> false
plugin.clearForceDisabled( 'OtherFeature' );
plugin.isEnabled; // -> true
```
Multiple disabling with the same identifier is redundant:
```typescript
plugin.forceDisabled( 'MyFeature' );
plugin.forceDisabled( 'MyFeature' );
plugin.clearForceDisabled( 'MyFeature' );
plugin.isEnabled; // -> true
```
**Note:** some plugins or algorithms may have more complex logic when it comes to enabling or disabling certain plugins, so the plugin might be still disabled after [`clearForceDisabled`](#function-clearForceDisabled) was used.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/plugin.ts#L111)
#### Parameters
* `id: string`
Unique identifier for disabling. Use the same id when [enabling back](#function-clearForceDisabled) the plugin.
#### Returns
* `void`
### `getPositionOptions() → Partial | undefined`
Returns position options of the last view in the stack. This keeps the balloon in the same position when the view is changed.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L339)
#### Returns
* `Partial | undefined`
### `hasView( view ) → boolean`
Returns `true` when the given view is in one of the stacks. Otherwise returns `false`.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L203)
#### Parameters
* `view: View`
#### Returns
* `boolean`
### `listenTo( emitter, event, callback, options? ) → void` _(inherited)_
Registers a callback function to be executed when an event is fired in a specific (emitter) object.
Events can be grouped in namespaces using `:`. When namespaced event is fired, it additionally fires all callbacks for that namespace.
```typescript
// myEmitter.on( ... ) is a shorthand for myEmitter.listenTo( myEmitter, ... ).
myEmitter.on( 'myGroup', genericCallback );
myEmitter.on( 'myGroup:myEvent', specificCallback );
// genericCallback is fired.
myEmitter.fire( 'myGroup' );
// both genericCallback and specificCallback are fired.
myEmitter.fire( 'myGroup:myEvent' );
// genericCallback is fired even though there are no callbacks for "foo".
myEmitter.fire( 'myGroup:foo' );
```
An event callback can [stop the event](module_utils_eventinfo-EventInfo.md#member-stop) and set the [return value](module_utils_eventinfo-EventInfo.md#member-return) of the [`fire`](#function-fire) method.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L475)
#### Type parameters
* `TEvent: extends BaseEvent`
The type describing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).
#### Parameters
* `emitter: Emitter`
The object that fires the event.
* `event: TEvent[ 'name' ]`
The name of the event.
* `callback: GetCallback`
The function to be called on event.
* `options?: GetCallbackOptions`
Additional options.
#### Returns
* `void`
### `off( event, callback ) → void` _(inherited)_
Stops executing the callback on the given event. Shorthand for [`this.stopListening( this, event, callback )`](#function-stopListening:BASE_STOP).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L444)
#### Parameters
* `event: string`
The name of the event.
* `callback: Function`
The function to stop being called.
#### Returns
* `void`
### `on( event, callback, options? ) → void` _(inherited)_
Registers a callback function to be executed when an event is fired.
Shorthand for [`this.listenTo( this, event, callback, options )`](#function-listenTo:BASE_EMITTER) (it makes the emitter listen on itself).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L416)
#### Type parameters
* `TEvent: extends BaseEvent`
The type descibing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).
#### Parameters
* `event: TEvent[ 'name' ]`
The name of the event.
* `callback: GetCallback`
The function to be called on event.
* `options?: GetCallbackOptions`
Additional options.
#### Returns
* `void`
### `once( event, callback, options? ) → void` _(inherited)_
Registers a callback function to be executed on the next time the event is fired only. This is similar to calling [`on`](#function-on) followed by [`off`](#function-off) in the callback.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L431)
#### Type parameters
* `TEvent: extends BaseEvent`
The type descibing the event. See [`BaseEvent`](module_utils_emittermixin-BaseEvent.md).
#### Parameters
* `event: TEvent[ 'name' ]`
The name of the event.
* `callback: GetCallback`
The function to be called on event.
* `options?: GetCallbackOptions`
Additional options.
#### Returns
* `void`
### `remove( view ) → void`
Removes the given view from the stack. If the removed view was visible, the view preceding it in the stack will become visible instead. When there is no view in the stack, the next stack will be displayed. When there are no more stacks, the balloon will hide.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L275)
#### Parameters
* `view: View`
A view to be removed from the balloon.
#### Returns
* `void`
### `set( values ) → void` _(inherited)_
Creates and sets the value of an observable properties of this object. Such a property becomes a part of the state and is observable.
It accepts a single object literal containing key/value pairs with properties to be set.
This method throws the `observable-set-cannot-override` error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that `foo.set( 'bar', 1 )` may be slightly slower than `foo.bar = 1`.
In TypeScript, those properties should be declared in class using `declare` keyword. In example:
```typescript
public declare myProp1: number;
public declare myProp2: string;
constructor() {
this.set( {
'myProp1: 2,
'myProp2: 'foo'
} );
}
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L843)
#### Parameters
* `values: object & object`
An object with `name=>value` pairs.
#### Returns
* `void`
### `set( name, value ) → void` _(inherited)_
Creates and sets the value of an observable property of this object. Such a property becomes a part of the state and is observable.
This method throws the `observable-set-cannot-override` error if the observable instance already has a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that `foo.set( 'bar', 1 )` may be slightly slower than `foo.bar = 1`.
In TypeScript, those properties should be declared in class using `declare` keyword. In example:
```typescript
public declare myProp: number;
constructor() {
this.set( 'myProp', 2 );
}
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L815)
#### Type parameters
* `K`
#### Parameters
* `name: K`
The property's name.
* `value: ContextualBalloon[ K ]`
The property's value.
#### Returns
* `void`
### `showStack( id ) → void`
Shows the last view from the stack of a given ID.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L366)
#### Parameters
* `id: string`
#### Returns
* `void`
### `stopDelegating( event?, emitter? ) → void` _(inherited)_
Stops delegating events. It can be used at different levels:
* To stop delegating all events.
* To stop delegating a specific event to all emitters.
* To stop delegating a specific event to a specific emitter.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L552)
#### Parameters
* `event?: string`
The name of the event to stop delegating. If omitted, stops it all delegations.
* `emitter?: Emitter`
(requires `event`) The object to stop delegating a particular event to. If omitted, stops delegation of `event` to all emitters.
#### Returns
* `void`
### `stopListening( emitter?, event?, callback? ) → void` _(inherited)_
Stops listening for events. It can be used at different levels:
* To stop listening to a specific callback.
* To stop listening to a specific event.
* To stop listening to all events fired by a specific object.
* To stop listening to all events fired by all objects.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/emittermixin.ts#L497)
#### Parameters
* `emitter?: Emitter`
The object to stop listening to. If omitted, stops it for all objects.
* `event?: string`
(Requires the `emitter`) The name of the event to stop listening to. If omitted, stops it for all events from `emitter`.
* `callback?: Function`
(Requires the `event`) The function to be removed from the call list for the given `event`.
#### Returns
* `void`
### `unbind( unbindProperties ) → void` _(inherited)_
Removes the binding created with [`bind`](#function-bind:SINGLE_BIND).
```typescript
// Removes the binding for the 'a' property.
A.unbind( 'a' );
// Removes bindings for all properties.
A.unbind();
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1090)
#### Parameters
* `unbindProperties: Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'view' | 'destroy' | 'remove' | 'add' | 'positionLimiter' | 'visibleStack' | 'visibleView' | '_numberOfStacks' | '_singleViewMode' | 'editor' | 'isEnabled' | 'forceDisabled' | 'clearForceDisabled' | 'updatePosition' | 'getPositionOptions' | 'hasView' | 'showStack'>`
Observable properties to be unbound. All the bindings will be released if no properties are provided.
#### Returns
* `void`
### `updatePosition( position? ) → void`
Updates the position of the balloon using the position data of the first visible view in the stack. When new position data is given, the position data of the currently visible view will be updated.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L326)
#### Parameters
* `position?: Partial`
Position options.
#### Returns
* `void`
### `_createFakePanelsView() → FakePanelsView` _(private)_
Creates a fake panels view.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L501)
#### Returns
* `FakePanelsView`
### `_createPanelView() → void` _(private)_
Initializes view instances.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L392)
#### Returns
* `void`
### `_createRotatorView() → RotatorView` _(private)_
Creates a rotator view.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L450)
#### Returns
* `RotatorView`
### `_getStackId( stack ) → string` _(private)_
Returns the ID of the given stack.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L411)
#### Parameters
* `stack: Stack`
#### Returns
* `string`
### `_showNextStack() → void` _(private)_
Shows the last view from the next stack.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L420)
#### Returns
* `void`
### `_showPrevStack() → void` _(private)_
Shows the last view from the previous stack.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L435)
#### Returns
* `void`
### `_showView( data ) → void` _(private)_
Sets the view as the content of the balloon and attaches the balloon using position options of the first view.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L527)
#### Parameters
* `data: ViewConfiguration`
Configuration.
#### Returns
* `void`
## Events
### `change:_numberOfStacks( eventInfo, name, value, oldValue )`
Fired when the `_numberOfStacks` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L94)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`_numberOfStacks`).
* `value: number`
New value of the `_numberOfStacks` property with given key or `null`, if operation should remove property.
* `oldValue: number`
Old value of the `_numberOfStacks` property with given key or `null`, if property was not set before.
### `change:_singleViewMode( eventInfo, name, value, oldValue )`
Fired when the `_singleViewMode` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L103)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`_singleViewMode`).
* `value: boolean`
New value of the `_singleViewMode` property with given key or `null`, if operation should remove property.
* `oldValue: boolean`
Old value of the `_singleViewMode` property with given key or `null`, if property was not set before.
### `change:isEnabled( eventInfo, name, value, oldValue )` _(inherited)_
Fired when the `isEnabled` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/plugin.ts#L51)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`isEnabled`).
* `value: boolean`
New value of the `isEnabled` property with given key or `null`, if operation should remove property.
* `oldValue: boolean`
Old value of the `isEnabled` property with given key or `null`, if property was not set before.
### `change:visibleView( eventInfo, name, value, oldValue )`
Fired when the `visibleView` property changed value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L85)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`visibleView`).
* `value: View | null`
New value of the `visibleView` property with given key or `null`, if operation should remove property.
* `oldValue: View | null`
Old value of the `visibleView` property with given key or `null`, if property was not set before.
### `change:{property}( eventInfo, name, value, oldValue )` _(inherited)_
Fired when a property changed value.
```typescript
observable.set( 'prop', 1 );
observable.on>( 'change:prop', ( evt, propertyName, newValue, oldValue ) => {
console.log( `${ propertyName } has changed from ${ oldValue } to ${ newValue }` );
} );
observable.prop = 2; // -> 'prop has changed from 1 to 2'
```
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1190)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
The property name.
* `value: TValue`
The new property value.
* `oldValue: TValue`
The previous property value.
### `getPositionOptions( eventInfo, )`
An event fired when the [`ContextualBalloon`](module_ui_panel_balloon_contextualballoon-ContextualBalloon.md) is about to get the position of the balloon.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L547)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `: Parameters`
### `set:_numberOfStacks( eventInfo, name, value, oldValue )`
Fired when the `_numberOfStacks` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L94)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`_numberOfStacks`).
* `value: number`
New value of the `_numberOfStacks` property with given key or `null`, if operation should remove property.
* `oldValue: number`
Old value of the `_numberOfStacks` property with given key or `null`, if property was not set before.
### `set:_singleViewMode( eventInfo, name, value, oldValue )`
Fired when the `_singleViewMode` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L103)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`_singleViewMode`).
* `value: boolean`
New value of the `_singleViewMode` property with given key or `null`, if operation should remove property.
* `oldValue: boolean`
Old value of the `_singleViewMode` property with given key or `null`, if property was not set before.
### `set:isEnabled( eventInfo, name, value, oldValue )` _(inherited)_
Fired when the `isEnabled` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-core/src/plugin.ts#L51)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`isEnabled`).
* `value: boolean`
New value of the `isEnabled` property with given key or `null`, if operation should remove property.
* `oldValue: boolean`
Old value of the `isEnabled` property with given key or `null`, if property was not set before.
### `set:visibleView( eventInfo, name, value, oldValue )`
Fired when the `visibleView` property is going to be set but is not set yet (before the `change` event is fired).
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-ui/src/panel/balloon/contextualballoon.ts#L85)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
Name of the changed property (`visibleView`).
* `value: View | null`
New value of the `visibleView` property with given key or `null`, if operation should remove property.
* `oldValue: View | null`
Old value of the `visibleView` property with given key or `null`, if property was not set before.
### `set:{property}( eventInfo, name, value, oldValue )` _(inherited)_
Fired when a property value is going to be set but is not set yet (before the `change` event is fired).
You can control the final value of the property by using the [event's `return` property](module_utils_eventinfo-EventInfo.md#member-return).
```typescript
observable.set( 'prop', 1 );
observable.on>( 'set:prop', ( evt, propertyName, newValue, oldValue ) => {
console.log( `Value is going to be changed from ${ oldValue } to ${ newValue }` );
console.log( `Current property value is ${ observable[ propertyName ] }` );
// Let's override the value.
evt.return = 3;
} );
observable.on>( 'change:prop', ( evt, propertyName, newValue, oldValue ) => {
console.log( `Value has changed from ${ oldValue } to ${ newValue }` );
} );
observable.prop = 2; // -> 'Value is going to be changed from 1 to 2'
// -> 'Current property value is 1'
// -> 'Value has changed from 1 to 3'
```
**Note:** The event is fired even when the new value is the same as the old value.
[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-utils/src/observablemixin.ts#L1228)
#### Parameters
* `eventInfo: EventInfo`
An object containing information about the fired event.
* `name: string`
The property name.
* `value: TValue`
The new property value.
* `oldValue: TValue`
The previous property value.
---
Full index of the CKEditor 5 API reference: [llms.txt](llms.txt)