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Class

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 Writer:

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 bind DOM and View elements.

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

Filtering

Properties

Methods

  • addObserver( Observer ) → Observer

    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

    Observer : function

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

    Returns

    Observer

    Added observer instance.

  • attachDomRoot( domRoot, [ name ] )

    Attaches 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.

    Parameters

    domRoot : Element

    DOM root element.

    [ name ] : String

    Name of the root.

    Defaults to 'main'

  • bind( bindProperties ) → Object

    mixed

    Binds observable properties to another objects implementing Observable interface (like Model).

    Once bound, the observable will immediately share the current state of properties of the observable it is bound to and react to the changes to these properties in the future.

    Note: To release the binding use unbind.

    Using bind().to() chain:

    A.bind( 'a' ).to( B );
    A.bind( 'a' ).to( B, 'b' );
    A.bind( 'a', 'b' ).to( B, 'c', 'd' );
    A.bind( 'a' ).to( B, 'b', C, 'd', ( b, d ) => b + d );

    It is also possible to bind to the same property in a observables collection using bind().toMany() chain:

    A.bind( 'a' ).toMany( [ B, C, D ], 'x', ( a, b, c ) => a + b + c );
    A.bind( 'a' ).toMany( [ B, C, D ], 'x', ( ...x ) => x.every( x => x ) );

    Parameters

    bindProperties : String

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

    Returns

    Object

    The bind chain with the to() and toMany() methods.

  • change( callback )

    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 view is rendered to DOM. It prevents situations when DOM is updated when view state is not yet correct. It allows to nest calls one inside another and still perform single rendering after all changes are applied.

    view.change( writer => {
        writer.insert( position1, writer.createText( 'foo' ) );
    
        view.change( writer => {
            writer.insert( position2, writer.createText( 'bar' ) );
        } );
    
        writer.remove( range );
    } );

    Change block is executed immediately.

    When the outermost change block is done and rendering to DOM is over it fires event-render event.

    Throws CKEditorError applying-view-changes-on-rendering when change block is used after rendering to DOM has started.

    Parameters

    callback : function

    Callback function which may modify the view.

  • decorate( methodName )

    mixed

    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.

    This is a very simplified method decoration. Itself it doesn't change the behavior of a method (expect adding the event), but it allows to modify it later on by listening to the method's event.

    For example, in order to cancel the method execution one can stop the event:

    class Foo {
        constructor() {
            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: we used a high priority listener here to execute this callback before the one which calls the original method (which used the default priority).

    It's also possible to change the return value:

    foo.on( 'method', ( evt ) => {
        evt.return = 'Foo!';
    } );
    
    foo.method(); // -> 'Foo'

    Finally, it's possible to access and modify the parameters:

    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 : String

    Name of the method to decorate.

  • delegate( events ) → EmitterMixinDelegateChain

    mixed

    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 : String

    Event names that will be delegated to another emitter.

    Returns

    EmitterMixinDelegateChain
  • Destroys this instance. Makes sure that all observers are destroyed and listeners removed.

  • Disables all added observers.

  • Enables all added observers.

  • fire( eventOrInfo, [ args ] ) → *

    mixed

    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.

    Parameters

    eventOrInfo : String | EventInfo

    The name of the event or EventInfo object if event is delegated.

    [ args ] : *

    Additional arguments to be passed to the callbacks.

    Returns

    *

    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()

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

  • getDomRoot( [ name ] ) → Element

    Gets DOM root element.

    Parameters

    [ name ] : String

    Name of the root.

    Defaults to 'main'

    Returns

    Element

    DOM root element instance.

  • getObserver( Observer ) → Observer | undefined

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

    Parameters

    Observer : function

    The constructor of an observer to get.

    Returns

    Observer | undefined

    Observer instance or undefined.

  • listenTo( emitter, event, callback, [ options ] = { [options.priority] } )

    mixed

    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.

    Parameters

    emitter : Emitter

    The object that fires the event.

    event : String

    The name of the event.

    callback : function

    The function to be called on event.

    [ options ] : Object

    Additional options.

    Properties
    [ options.priority ] : PriorityString | Number

    The priority of this event callback. The higher the priority value the sooner the callback will be fired. Events having the same priority are called in the order they were added.

    Defaults to 'normal'

    Defaults to {}

  • off( event, callback )

    mixed

    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.

  • on( event, callback, [ options ] = { [options.priority] } )

    mixed

    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).

    Parameters

    event : String

    The name of the event.

    callback : function

    The function to be called on event.

    [ options ] : Object

    Additional options.

    Properties
    [ options.priority ] : PriorityString | Number

    The priority of this event callback. The higher the priority value the sooner the callback will be fired. Events having the same priority are called in the order they were added.

    Defaults to 'normal'

    Defaults to {}

  • once( event, callback, [ options ] = { [options.priority] } )

    mixed

    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.

    Parameters

    event : String

    The name of the event.

    callback : function

    The function to be called on event.

    [ options ] : Object

    Additional options.

    Properties
    [ options.priority ] : PriorityString | Number

    The priority of this event callback. The higher the priority value the sooner the callback will be fired. Events having the same priority are called in the order they were added.

    Defaults to 'normal'

    Defaults to {}

  • render()

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

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

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

  • set( name, [ value ] )

    mixed

    Creates and sets the value of an observable property of this object. Such an property becomes a part of the state and is be observable.

    It accepts also 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 have 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.

    Parameters

    name : String | Object

    The property's name or object with name=>value pairs.

    [ value ] : *

    The property's value (if name was passed in the first parameter).

  • stopDelegating( [ event ], [ emitter ] )

    mixed

    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.

  • stopListening( [ emitter ], [ event ], [ callback ] )

    mixed

    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.

  • unbind( [ unbindProperties ] )

    mixed

    Removes the binding created with bind.

    A.unbind( 'a' );
    A.unbind();

    Parameters

    [ unbindProperties ] : String

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

  • _render()

    private

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

Events

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

    mixed

    Fired when a property changed value.

    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'

    Parameters

    eventInfo : EventInfo

    An object containing information about the fired event.

    name : String

    The property name.

    value : *

    The new property value.

    oldValue : *

    The previous property value.

  • render( eventInfo )

    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.