View (engine/view)

@ckeditor/ckeditor5-engine/src/view/view

class

Editor's view controller class. Its main responsibility is DOM - View management for editing purposes, to provide abstraction over the DOM structure and events and hide all browsers quirks.

View controller renders view document to DOM whenever view structure changes. To determine when view can be rendered, all changes need to be done using the change method, using DowncastWriter:

view.change( writer => {
	writer.insert( position, writer.createText( 'foo' ) );
} );

View controller also register observers which observes changes on DOM and fire events on the Document. Note that the following observers are added by the class constructor and are always available:

This class also binds the DOM and the view elements.

If you do not need full a DOM - view management, and only want to transform a tree of view elements to a tree of DOM elements you do not need this controller. You can use the DomConverter instead.

Filtering

Public
Inherited
Internal
Protected
Private
Deprecated

Properties

readonly
document : Document

See source
Instance of the Document associated with this view controller.
readonly
domConverter : DomConverter

See source
Instance of the domConverter used by renderer and observers.
readonly
domRoots : Map<string, HTMLElement>

See source
Roots of the DOM tree. Map on the HTMLElements with roots names as keys.
observable
hasDomSelection : boolean

See source
Informs whether the DOM selection is inside any of the DOM roots managed by the view.
observable
isRenderingInProgress : boolean

See source
Used to prevent calling forceRender and change during rendering view to the DOM.
private
_hasChangedSinceTheLastRendering : boolean

See source
Internal flag that disables rendering when there are no changes since the last rendering. It stores information about changed selection and changed elements from attached document roots.
private readonly
_initialDomRootAttributes : WeakMap<HTMLElement, Record<string, string>>

See source
A DOM root attributes cache. It saves the initial values of DOM root attributes before the DOM element is attached to the view so later on, when the view is destroyed (detachDomRoot), they can be easily restored. This way, the DOM element can go back to the (clean) state as if the editing view never used it.
private readonly
_observers : Map<ObserverConstructor, Observer>

See source
Map of registered observers.
private
_ongoingChange : boolean

See source
Is set to true when view changes are currently in progress.
private
_postFixersInProgress : boolean

See source
Used to prevent calling forceRender and change during rendering view to the DOM.
private readonly
_renderer : Renderer

See source
Instance of the renderer.
private
_renderingDisabled : boolean

See source
Internal flag to temporary disable rendering. See the usage in the _disableRendering.
private readonly
_writer : DowncastWriter

See source
DowncastWriter instance used in change method callbacks.

Methods

constructor( stylesProcessor )

See source

Parameters

stylesProcessor : StylesProcessor

The styles processor instance.
addObserver( ObserverConstructor ) → Observer

See source
Creates observer of the given type if not yet created, enables it and attaches to all existing and future DOM roots.

Note: Observers are recognized by their constructor (classes). A single observer will be instantiated and used only when registered for the first time. This means that features and other components can register a single observer multiple times without caring whether it has been already added or not.

Parameters

ObserverConstructor : ObserverConstructor

The constructor of an observer to add. Should create an instance inheriting from Observer.

Returns

Observer

Added observer instance.
attachDomRoot( domRoot, name ) → void

See source
Attaches a DOM root element to the view element and enable all observers on that element. Also mark element to be synchronized with the view what means that all child nodes will be removed and replaced with content of the view root.

This method also will change view element name as the same as tag name of given dom root. Name is always transformed to lower case.

Note: Use detachDomRoot() to revert this action.

Parameters

domRoot : HTMLElement

DOM root element.

name : string

Name of the root.

Defaults to 'main'

Returns

void
inherited
bind( bindProperties ) → MultiBindChain
See source
Binds observable properties to other objects implementing the Observable interface.

Read more in the dedicated 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:
```
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```
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.

You can also "rename" the property in the binding by specifying the new name in the to() chain:
```
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```
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:
```
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:
```
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:
```
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
	( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
Parameters

bindProperties : Array<'off' | 'on' | 'once' | 'listenTo' | 'stopListening' | 'fire' | 'delegate' | 'stopDelegating' | 'set' | 'bind' | 'unbind' | 'decorate' | 'change' | 'focus' | 'document' | 'destroy' | 'createPositionAt' | 'createPositionAfter' | 'createPositionBefore' | 'createRange' | 'createRangeIn' | 'createRangeOn' | 'createSelection' | 'domConverter' | 'domRoots' | 'isRenderingInProgress' | 'hasDomSelection' | 'attachDomRoot' | 'detachDomRoot' | 'getDomRoot' | 'addObserver' | 'getObserver' | 'disableObservers' | 'enableObservers' | 'scrollToTheSelection' | 'forceRender' | '_disableRendering'>

Observable properties that will be bound to other observable(s).

Returns

MultiBindChain

The bind chain with the to() and toMany() methods.
inherited
bind( bindProperty1, bindProperty2 ) → DualBindChain<K1, View[ K1 ], K2, View[ K2 ]>
See source
Binds observable properties to other objects implementing the Observable interface.

Read more in the dedicated 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:
```
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```
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.

You can also "rename" the property in the binding by specifying the new name in the to() chain:
```
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```
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:
```
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:
```
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:
```
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
	( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
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

DualBindChain<K1, View[ K1 ], K2, View[ K2 ]>

The bind chain with the to() and toMany() methods.
inherited
bind( bindProperty ) → SingleBindChain<K, View[ K ]>
See source
Binds observable properties to other objects implementing the Observable interface.

Read more in the dedicated 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:
```
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```
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.

You can also "rename" the property in the binding by specifying the new name in the to() chain:
```
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```
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:
```
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:
```
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:
```
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
	( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
Type parameters

K

Parameters

bindProperty : K

Observable property that will be bound to other observable(s).

Returns

SingleBindChain<K, View[ K ]>

The bind chain with the to() and toMany() methods.
change( callback ) → TReturn
See source
The change() method is the primary way of changing the view. You should use it to modify any node in the view tree. It makes sure that after all changes are made the view is rendered to the DOM (assuming that the view will be changed inside the callback). It prevents situations when the DOM is updated when the view state is not yet correct. It allows to nest calls one inside another and still performs a single rendering after all those changes are made. It also returns the return value of its callback.
```
const text = view.change( writer => {
	const newText = writer.createText( 'foo' );
	writer.insert( position1, newText );

	view.change( writer => {
		writer.insert( position2, writer.createText( 'bar' ) );
	} );

	writer.remove( range );

	return newText;
} );
```
When the outermost change block is done and rendering to the DOM is over the View#render event is fired.

This method throws a applying-view-changes-on-rendering error when the change block is used after rendering to the DOM has started.

Type parameters

TReturn

Parameters

callback : ( DowncastWriter ) => TReturn

Callback function which may modify the view.

Returns

TReturn

Value returned by the callback.
createPositionAfter( item ) → Position

See source
Creates a new position after given view item.

Parameters

item : Item

View item after which the position should be located.

Returns

Position
createPositionAt( itemOrPosition, [ offset ] ) → Position
See source
Creates position at the given location. The location can be specified as:
- a position,
- parent element and offset (offset defaults to 0),
- parent element and 'end' (sets position at the end of that element),
- view item and 'before' or 'after' (sets position before or after given view item).
This method is a shortcut to other constructors such as:
- createPositionBefore,
- createPositionAfter,
Parameters

itemOrPosition : Position | Item

[ offset ] : PositionOffset

Offset or one of the flags. Used only when first parameter is a view item.

Returns

Position
createPositionBefore( item ) → Position

See source
Creates a new position before given view item.

Parameters

item : Item

View item before which the position should be located.

Returns

Position
createRange( start, [ end ] ) → Range

See source
Creates a range spanning from start position to end position.

Note: This factory method creates it's own Position instances basing on passed values.

Parameters

start : Position

Start position.

[ end ] : null | Position

End position. If not set, range will be collapsed at start position.

Returns

Range
createRangeIn( element ) → Range

See source
Creates a range inside an element which starts before the first child of that element and ends after the last child of that element.

Parameters

element : Element

Element which is a parent for the range.

Returns

Range
createRangeOn( item ) → Range

See source
Creates a range that starts before given view item and ends after it.

Parameters

item : Item

Returns

Range

`createSelection( [ selectable ], [ options ] ) → Selection`

See source

Creates new Selection instance.

// Creates empty selection without ranges.
const selection = view.createSelection();

// Creates selection at the given range.
const range = view.createRange( start, end );
const selection = view.createSelection( range );

// Creates selection at the given ranges
const ranges = [ view.createRange( start1, end2 ), view.createRange( star2, end2 ) ];
const selection = view.createSelection( ranges );

// Creates selection from the other selection.
const otherSelection = view.createSelection();
const selection = view.createSelection( otherSelection );

// Creates selection from the document selection.
const selection = view.createSelection( editor.editing.view.document.selection );

// Creates selection at the given position.
const position = view.createPositionFromPath( root, path );
const selection = view.createSelection( position );

Selection's factory method allow passing additional options (backward, fake and label) as the last argument.

// Creates backward selection.
const selection = view.createSelection( range, { backward: true } );

Fake selection does not render as browser native selection over selected elements and is hidden to the user. This way, no native selection UI artifacts are displayed to the user and selection over elements can be represented in other way, for example by applying proper CSS class.

Additionally fake's selection label can be provided. It will be used to describe fake selection in DOM (and be properly handled by screen readers).

// Creates fake selection with label.
const selection = view.createSelection( range, { fake: true, label: 'foo' } );

Parameters

[ selectable ] : null | Position | Range | Selection | DocumentSelection | Iterable<Range>
[ options ] : SelectionOptions

Returns

Selection

createSelection( selectable, placeOrOffset, [ options ] ) → Selection
See source
Creates new Selection instance.
```
// Creates collapsed selection at the position of given item and offset.
const paragraph = view.createContainerElement( 'paragraph' );
const selection = view.createSelection( paragraph, offset );

// Creates a range inside an element which starts before the
// first child of that element and ends after the last child of that element.
const selection = view.createSelection( paragraph, 'in' );

// Creates a range on an item which starts before the item and ends
// just after the item.
const selection = view.createSelection( paragraph, 'on' );
```
Selection's factory method allow passing additional options (backward, fake and label) as the last argument.
```
// Creates backward selection.
const selection = view.createSelection( paragraph, 'in', { backward: true } );
```
Fake selection does not render as browser native selection over selected elements and is hidden to the user. This way, no native selection UI artifacts are displayed to the user and selection over elements can be represented in other way, for example by applying proper CSS class.

Additionally fake's selection label can be provided. It will be used to describe fake selection in DOM (and be properly handled by screen readers).
```
// Creates fake selection with label.
const selection = view.createSelection( element, 'in', { fake: true, label: 'foo' } );
```
See also: createSelection( selectable, options ).

Parameters

selectable : Node

placeOrOffset : PlaceOrOffset

[ options ] : SelectionOptions

Returns

Selection
inherited
decorate( methodName ) → void
See source
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 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:
```
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 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:
```
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:
```
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'
```
Parameters

methodName : 'off' | 'on' | 'once' | 'listenTo' | 'stopListening' | 'fire' | 'delegate' | 'stopDelegating' | 'set' | 'bind' | 'unbind' | 'decorate' | 'change' | 'focus' | 'document' | 'destroy' | 'createPositionAt' | 'createPositionAfter' | 'createPositionBefore' | 'createRange' | 'createRangeIn' | 'createRangeOn' | 'createSelection' | 'domConverter' | 'domRoots' | 'isRenderingInProgress' | 'hasDomSelection' | 'attachDomRoot' | 'detachDomRoot' | 'getDomRoot' | 'addObserver' | 'getObserver' | 'disableObservers' | 'enableObservers' | 'scrollToTheSelection' | 'forceRender' | '_disableRendering'

Name of the method to decorate.

Returns

void
inherited
delegate( events ) → EmitterMixinDelegateChain
See source
Delegates selected events to another Emitter. For instance:
```
emitterA.delegate( 'eventX' ).to( emitterB );
emitterA.delegate( 'eventX', 'eventY' ).to( emitterC );
```
then eventX is delegated (fired by) emitterB and emitterC along with data:
```
emitterA.fire( 'eventX', data );
```
and eventY is delegated (fired by) emitterC along with data:
```
emitterA.fire( 'eventY', data );
```
Parameters

events : Array<string>

Event names that will be delegated to another emitter.

Returns

EmitterMixinDelegateChain
destroy() → void

See source
Destroys this instance. Makes sure that all observers are destroyed and listeners removed.

Returns

void
detachDomRoot( name ) → void

See source
Detaches a DOM root element from the view element and restores its attributes to the state before attachDomRoot().

Parameters

name : string

Name of the root to detach.

Returns

void
disableObservers() → void

See source
Disables all added observers.

Returns

void
enableObservers() → void

See source
Enables all added observers.

Returns

void
inherited
fire( eventOrInfo, args ) → GetEventInfo<TEvent>[ 'return' ]

See source
Fires an event, executing all callbacks registered for it.

The first parameter passed to callbacks is an EventInfo object, followed by the optional args provided in the fire() method call.

Type parameters

TEvent : extends BaseEvent

The type describing the event. See BaseEvent.

Parameters

eventOrInfo : GetNameOrEventInfo<TEvent>

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<TEvent>[ 'return' ]

By default the method returns undefined. However, the return value can be changed by listeners through modification of the evt.return's property (the event info is the first param of every callback).
focus() → void

See source
It will focus DOM element representing EditableElement that is currently having selection inside.

Returns

void
forceRender() → void

See source
Forces rendering view document to DOM. If any view changes are currently in progress, rendering will start after all change blocks are processed.

Note that this method is dedicated for special cases. All view changes should be wrapped in the change block and the view will automatically check whether it needs to render DOM or not.

Throws CKEditorError applying-view-changes-on-rendering when trying to re-render when rendering to DOM has already started.

Returns

void
getDomRoot( name ) → undefined | HTMLElement

See source
Gets DOM root element.

Parameters

name : string

Name of the root.

Defaults to 'main'

Returns

undefined | HTMLElement

DOM root element instance.
getObserver( ObserverConstructor ) → object

See source
Returns observer of the given type or undefined if such observer has not been added yet.

Type parameters

T : extends ObserverConstructor

Parameters

ObserverConstructor : T

The constructor of an observer to get.

Returns

object

Observer instance or undefined.
inherited
listenTo( emitter, event, callback, [ options ] ) → void
See source
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.
```
// 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 and set the return value of the fire method.

Type parameters

TEvent : extends BaseEvent

The type describing the event. See BaseEvent.

Parameters

emitter : Emitter

The object that fires the event.

event : TEvent[ 'name' ]

The name of the event.

callback : GetCallback<TEvent>

The function to be called on event.

[ options ] : GetCallbackOptions<TEvent>

Additional options.

Returns

void
inherited
off( event, callback ) → void

See source
Stops executing the callback on the given event. Shorthand for this.stopListening( this, event, callback ).

Parameters

event : string

The name of the event.

callback : Function

The function to stop being called.

Returns

void
inherited
on( event, callback, [ options ] ) → void

See source
Registers a callback function to be executed when an event is fired.

Shorthand for this.listenTo( this, event, callback, options ) (it makes the emitter listen on itself).

Type parameters

TEvent : extends BaseEvent

The type descibing the event. See BaseEvent.

Parameters

event : TEvent[ 'name' ]

The name of the event.

callback : GetCallback<TEvent>

The function to be called on event.

[ options ] : GetCallbackOptions<TEvent>

Additional options.

Returns

void
inherited
once( event, callback, [ options ] ) → void

See source
Registers a callback function to be executed on the next time the event is fired only. This is similar to calling on followed by off in the callback.

Type parameters

TEvent : extends BaseEvent

The type descibing the event. See BaseEvent.

Parameters

event : TEvent[ 'name' ]

The name of the event.

callback : GetCallback<TEvent>

The function to be called on event.

[ options ] : GetCallbackOptions<TEvent>

Additional options.

Returns

void
scrollToTheSelection( options = { [options.alignToTop], [options.ancestorOffset], [options.forceScroll], [options.viewportOffset] } ) → void

See source
Scrolls the page viewport and domRoots with their ancestors to reveal the caret, if not already visible to the user.

Note: Calling this method fires the ViewScrollToTheSelectionEvent event that allows custom behaviors.

Type parameters

T : extends boolean

U : extends true

Parameters

options : object

Additional configuration of the scrolling behavior.

Properties

[ options.alignToTop ] : T

When set true, the DOM selection will be aligned to the top of the viewport if not already visible (see forceScroll to learn more).

[ options.ancestorOffset ] : number

A distance between the DOM selection and scrollable DOM root ancestor(s) to be maintained while scrolling to the selection (default is 20px). Setting this value to 0 will reveal the selection precisely at the scrollable ancestor(s) boundary.

[ options.forceScroll ] : U

When set true, the DOM selection will be aligned to the top of the viewport and scrollable ancestors whether it is already visible or not. This option will only work when alignToTop is true.

[ options.viewportOffset ] : number | object

A distance between the DOM selection and the viewport boundary to be maintained while scrolling to the selection (default is 20px). Setting this value to 0 will reveal the selection precisely at the viewport boundary.

Defaults to {}

Returns

void
inherited
set( values ) → void
See source
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:
```
public declare myProp1: number;
public declare myProp2: string;

constructor() {
	this.set( {
		'myProp1: 2,
		'myProp2: 'foo'
	} );
}
```
Parameters

values : object

An object with name=>value pairs.

Returns

void
inherited
set( name, value ) → void
See source
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:
```
public declare myProp: number;

constructor() {
	this.set( 'myProp', 2 );
}
```
Type parameters

K

Parameters

name : K

The property's name.

value : View[ K ]

The property's value.

Returns

void
inherited
stopDelegating( [ event ], [ emitter ] ) → void
See source
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.
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
inherited
stopListening( [ emitter ], [ event ], [ callback ] ) → void
See source
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.
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
inherited
unbind( unbindProperties ) → void
See source
Removes the binding created with bind.
```
// Removes the binding for the 'a' property.
A.unbind( 'a' );

// Removes bindings for all properties.
A.unbind();
```
Parameters

unbindProperties : Array<'off' | 'on' | 'once' | 'listenTo' | 'stopListening' | 'fire' | 'delegate' | 'stopDelegating' | 'set' | 'bind' | 'unbind' | 'decorate' | 'change' | 'focus' | 'document' | 'destroy' | 'createPositionAt' | 'createPositionAfter' | 'createPositionBefore' | 'createRange' | 'createRangeIn' | 'createRangeOn' | 'createSelection' | 'domConverter' | 'domRoots' | 'isRenderingInProgress' | 'hasDomSelection' | 'attachDomRoot' | 'detachDomRoot' | 'getDomRoot' | 'addObserver' | 'getObserver' | 'disableObservers' | 'enableObservers' | 'scrollToTheSelection' | 'forceRender' | '_disableRendering'>

Observable properties to be unbound. All the bindings will be released if no properties are provided.

Returns

void
internal
_disableRendering( flag ) → void

See source
Disables or enables rendering. If the flag is set to true then the rendering will be disabled. If the flag is set to false and if there was some change in the meantime, then the rendering action will be performed.

Parameters

flag : boolean

A flag indicates whether the rendering should be disabled.

Returns

void
private
_render() → void

See source
Renders all changes. In order to avoid triggering the observers (e.g. selection) all observers are disabled before rendering and re-enabled after that.

Returns

void

Events

change:hasDomSelection( eventInfo, name, value, oldValue )

See source
Fired when the hasDomSelection property changed value.

Parameters

eventInfo : EventInfo

An object containing information about the fired event.

name : string

Name of the changed property (hasDomSelection).

value : boolean

New value of the hasDomSelection property with given key or null, if operation should remove property.

oldValue : boolean

Old value of the hasDomSelection property with given key or null, if property was not set before.
change:isRenderingInProgress( eventInfo, name, value, oldValue )

See source
Fired when the isRenderingInProgress property changed value.

Parameters

eventInfo : EventInfo

An object containing information about the fired event.

name : string

Name of the changed property (isRenderingInProgress).

value : boolean

New value of the isRenderingInProgress property with given key or null, if operation should remove property.

oldValue : boolean

Old value of the isRenderingInProgress property with given key or null, if property was not set before.
inherited
change:{property}( eventInfo, name, value, oldValue )
See source
Fired when a property changed value.
```
observable.set( 'prop', 1 );

observable.on<ObservableChangeEvent<number>>( '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'
```
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.
render( eventInfo )
See source
Fired after a topmost change block and all post-fixers are executed.

Actual rendering is performed as a first listener on 'normal' priority.
```
view.on( 'render', () => {
	// Rendering to the DOM is complete.
} );
```
This event is useful when you want to update interface elements after the rendering, e.g. position of the balloon panel. If you wants to change view structure use post-fixers.

Parameters

eventInfo : EventInfo

An object containing information about the fired event.
scrollToTheSelection( eventInfo, <anonymous>, <anonymous> )
See source
An event fired at the moment of scrollToTheSelection being called. It carries two objects in its payload (args):
- The first argument is the object containing data that gets passed down to the scrollViewportToShowTarget helper. If some event listener modifies it, it can adjust the behavior of the scrolling (e.g. include additional viewportOffset).
- The second argument corresponds to the original arguments passed to scrollViewportToShowTarget. It allows listeners to re-execute the scrollViewportToShowTarget() method with its original arguments if there is such a need, for instance, if the integration requires re–scrolling after certain interaction.
Parameters

eventInfo : EventInfo

An object containing information about the fired event.

<anonymous> : ViewScrollToTheSelectionEventData

<anonymous> : Parameters<View[ 'scrollToTheSelection' ]>[ 0 ]
set:hasDomSelection( eventInfo, name, value, oldValue )

See source
Fired when the hasDomSelection property is going to be set but is not set yet (before the change event is fired).

Parameters

eventInfo : EventInfo

An object containing information about the fired event.

name : string

Name of the changed property (hasDomSelection).

value : boolean

New value of the hasDomSelection property with given key or null, if operation should remove property.

oldValue : boolean

Old value of the hasDomSelection property with given key or null, if property was not set before.
set:isRenderingInProgress( eventInfo, name, value, oldValue )

See source
Fired when the isRenderingInProgress property is going to be set but is not set yet (before the change event is fired).

Parameters

eventInfo : EventInfo

An object containing information about the fired event.

name : string

Name of the changed property (isRenderingInProgress).

value : boolean

New value of the isRenderingInProgress property with given key or null, if operation should remove property.

oldValue : boolean

Old value of the isRenderingInProgress property with given key or null, if property was not set before.
inherited
set:{property}( eventInfo, name, value, oldValue )
See source
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.
```
observable.set( 'prop', 1 );

observable.on<ObservableSetEvent<number>>( '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<ObservableChangeEvent<number>>( '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.

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.

Every day, we work hard to keep our documentation complete. Have you spotted outdated information? Is something missing? Please report it via our issue tracker.

With the release of version 42.0.0, we have rewritten much of our documentation to reflect the new import paths and features. We appreciate your feedback to help us ensure its accuracy and completeness.

View (engine/view)

Filtering

Properties

readonly document : Documentmodule:engine/view/view~View#document

readonly domConverter : DomConvertermodule:engine/view/view~View#domConverter

readonly domRoots : Map<string, HTMLElement>module:engine/view/view~View#domRoots

observable hasDomSelection : booleanmodule:engine/view/view~View#hasDomSelection

observable isRenderingInProgress : booleanmodule:engine/view/view~View#isRenderingInProgress

private _hasChangedSinceTheLastRendering : booleanmodule:engine/view/view~View#_hasChangedSinceTheLastRendering

private readonly _initialDomRootAttributes : WeakMap<HTMLElement, Record<string, string>>module:engine/view/view~View#_initialDomRootAttributes

private readonly _observers : Map<ObserverConstructor, Observer>module:engine/view/view~View#_observers

private _ongoingChange : booleanmodule:engine/view/view~View#_ongoingChange

private _postFixersInProgress : booleanmodule:engine/view/view~View#_postFixersInProgress

private readonly _renderer : Renderermodule:engine/view/view~View#_renderer

private _renderingDisabled : booleanmodule:engine/view/view~View#_renderingDisabled

private readonly _writer : DowncastWritermodule:engine/view/view~View#_writer

Methods

constructor( stylesProcessor )module:engine/view/view~View#constructor

Parameters

addObserver( ObserverConstructor ) → Observermodule:engine/view/view~View#addObserver

Parameters

Returns

attachDomRoot( domRoot, name ) → voidmodule:engine/view/view~View#attachDomRoot

Parameters

Returns

inherited bind( bindProperties ) → MultiBindChainmodule:engine/view/view~View#bind:MANY_BIND

Parameters

Returns

inherited bind( bindProperty1, bindProperty2 ) → DualBindChain<K1, View[ K1 ], K2, View[ K2 ]>module:engine/view/view~View#bind:DUAL_BIND

Type parameters

Parameters

Returns

inherited bind( bindProperty ) → SingleBindChain<K, View[ K ]>module:engine/view/view~View#bind:SINGLE_BIND

Type parameters

Parameters

Returns

change( callback ) → TReturnmodule:engine/view/view~View#change

Type parameters

Parameters

Returns

createPositionAfter( item ) → Positionmodule:engine/view/view~View#createPositionAfter

Parameters

Returns

createPositionAt( itemOrPosition, [ offset ] ) → Positionmodule:engine/view/view~View#createPositionAt

Parameters

Returns

createPositionBefore( item ) → Positionmodule:engine/view/view~View#createPositionBefore

Parameters

Returns

createRange( start, [ end ] ) → Rangemodule:engine/view/view~View#createRange

Parameters

Returns

createRangeIn( element ) → Rangemodule:engine/view/view~View#createRangeIn

Parameters

Returns

createRangeOn( item ) → Rangemodule:engine/view/view~View#createRangeOn

Parameters

Returns

createSelection( [ selectable ], [ options ] ) → Selectionmodule:engine/view/view~View#createSelection:SELECTABLE

Parameters

Returns

createSelection( selectable, placeOrOffset, [ options ] ) → Selectionmodule:engine/view/view~View#createSelection:NODE_OFFSET

Parameters

Returns

inherited decorate( methodName ) → voidmodule:engine/view/view~View#decorate

Parameters

Returns

inherited delegate( events ) → EmitterMixinDelegateChainmodule:engine/view/view~View#delegate

Parameters

Returns

destroy() → voidmodule:engine/view/view~View#destroy

Returns

detachDomRoot( name ) → voidmodule:engine/view/view~View#detachDomRoot

Parameters

Returns

disableObservers() → voidmodule:engine/view/view~View#disableObservers

Returns

enableObservers() → voidmodule:engine/view/view~View#enableObservers

Returns

inherited fire( eventOrInfo, args ) → GetEventInfo<TEvent>[ 'return' ]module:engine/view/view~View#fire

readonly
`document : Document`

readonly
`domConverter : DomConverter`

readonly
`domRoots : Map<string, HTMLElement>`

observable
`hasDomSelection : boolean`

observable
`isRenderingInProgress : boolean`

private
`_hasChangedSinceTheLastRendering : boolean`

private readonly
`_initialDomRootAttributes : WeakMap<HTMLElement, Record<string, string>>`

private readonly
`_observers : Map<ObserverConstructor, Observer>`

private
`_ongoingChange : boolean`

private
`_postFixersInProgress : boolean`

private readonly
`_renderer : Renderer`

private
`_renderingDisabled : boolean`

private readonly
`_writer : DowncastWriter`

`constructor( stylesProcessor )`

`addObserver( ObserverConstructor ) → Observer`

`attachDomRoot( domRoot, name ) → void`

inherited
`bind( bindProperties ) → MultiBindChain`

inherited
`bind( bindProperty1, bindProperty2 ) → DualBindChain<K1, View[ K1 ], K2, View[ K2 ]>`

inherited
`bind( bindProperty ) → SingleBindChain<K, View[ K ]>`

`change( callback ) → TReturn`

`createPositionAfter( item ) → Position`

`createPositionAt( itemOrPosition, [ offset ] ) → Position`

`createPositionBefore( item ) → Position`

`createRange( start, [ end ] ) → Range`

`createRangeIn( element ) → Range`

`createRangeOn( item ) → Range`

`createSelection( [ selectable ], [ options ] ) → Selection`

`createSelection( selectable, placeOrOffset, [ options ] ) → Selection`

inherited
`decorate( methodName ) → void`

inherited
`delegate( events ) → EmitterMixinDelegateChain`

`destroy() → void`

`detachDomRoot( name ) → void`

`disableObservers() → void`

`enableObservers() → void`

inherited
`fire( eventOrInfo, args ) → GetEventInfo<TEvent>[ 'return' ]`

`focus() → void`

`forceRender() → void`

`getDomRoot( name ) → undefined | HTMLElement`

`getObserver( ObserverConstructor ) → object`

inherited
`listenTo( emitter, event, callback, [ options ] ) → void`

inherited
`off( event, callback ) → void`

inherited
`on( event, callback, [ options ] ) → void`

inherited
`once( event, callback, [ options ] ) → void`

`scrollToTheSelection( options = { [options.alignToTop], [options.ancestorOffset], [options.forceScroll], [options.viewportOffset] } ) → void`

inherited
`set( values ) → void`

inherited
`set( name, value ) → void`

inherited
`stopDelegating( [ event ], [ emitter ] ) → void`

inherited
`stopListening( [ emitter ], [ event ], [ callback ] ) → void`

inherited
`unbind( unbindProperties ) → void`

internal
`_disableRendering( flag ) → void`

private
`_render() → void`

`change:hasDomSelection( eventInfo, name, value, oldValue )`

`change:isRenderingInProgress( eventInfo, name, value, oldValue )`

inherited
`change:{property}( eventInfo, name, value, oldValue )`

`render( eventInfo )`

`scrollToTheSelection( eventInfo, <anonymous>, <anonymous> )`

`set:hasDomSelection( eventInfo, name, value, oldValue )`

`set:isRenderingInProgress( eventInfo, name, value, oldValue )`

inherited
`set:{property}( eventInfo, name, value, oldValue )`