Renderer (engine/view)
@ckeditor/ckeditor5-engine/src/view/renderer
Renderer is responsible for updating the DOM structure and the DOM selection based on the information about updated view nodes. In other words, it renders the view to the DOM.
Its main responsibility is to make only the necessary, minimal changes to the DOM. However, unlike in many virtual DOM implementations, the primary reason for doing minimal changes is not the performance but ensuring that native editing features such as text composition, autocompletion, spell checking, selection's x-index are affected as little as possible.
Renderer uses DomConverter
to transform view nodes and positions
to and from the DOM.
Filtering
Properties
-
Converter instance.
-
Set of DOM Documents instances.
-
True if composition is in progress inside the document.
This property is bound to the
Document#isComposing
property. -
Indicates if the view document is focused and selection can be rendered. Selection will not be rendered if this is set to
false
. -
Indicates whether the user is making a selection in the document (e.g. holding the mouse button and moving the cursor). When they stop selecting, the property goes back to
false
.Note: In some browsers, the renderer will stop rendering the selection and inline fillers while the user is making a selection to avoid glitches in DOM selection (https://github.com/ckeditor/ckeditor5/issues/10562, https://github.com/ckeditor/ckeditor5/issues/10723).
-
Set of nodes which attributes changed and may need to be rendered.
-
Set of elements which child lists changed and may need to be rendered.
-
Set of text nodes which text data changed and may need to be rendered.
-
View selection. Renderer updates DOM selection based on the view selection.
-
private
_fakeSelectionContainer : null | HTMLElement
module:engine/view/renderer~Renderer#_fakeSelectionContainer
DOM element containing fake selection.
-
The text node in which the inline filler was rendered.
Methods
-
constructor( domConverter, selection )
module:engine/view/renderer~Renderer#constructor
Creates a renderer instance.
Parameters
domConverter : DomConverter
Converter instance.
selection : DocumentSelection
View selection.
-
inherited
bind( bindProperties ) → MultiBindChain
module:engine/view/renderer~Renderer#bind:MANY_BIND
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 associatedcommand
(bothObservable
).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 equalscommand.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 (alsoObservables
) 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' | 'render' | 'selection' | 'isFocused' | 'isSelecting' | 'isComposing' | 'domDocuments' | 'domConverter' | 'markedAttributes' | 'markedChildren' | 'markedTexts' | 'markToSync'>
Observable properties that will be bound to other observable(s).
Returns
MultiBindChain
The bind chain with the
to()
andtoMany()
methods.
-
inherited
bind( bindProperty1, bindProperty2 ) → DualBindChain<K1, Renderer[ K1 ], K2, Renderer[ K2 ]>
module:engine/view/renderer~Renderer#bind:DUAL_BIND
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 associatedcommand
(bothObservable
).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 equalscommand.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 (alsoObservables
) 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
-
inherited
bind( bindProperty ) → SingleBindChain<K, Renderer[ K ]>
module:engine/view/renderer~Renderer#bind:SINGLE_BIND
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 associatedcommand
(bothObservable
).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 equalscommand.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 (alsoObservables
) 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, Renderer[ K ]>
The bind chain with the
to()
andtoMany()
methods.
-
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' | 'render' | 'selection' | 'isFocused' | 'isSelecting' | 'isComposing' | 'domDocuments' | 'domConverter' | 'markedAttributes' | 'markedChildren' | 'markedTexts' | 'markToSync'
Name of the method to decorate.
Returns
void
-
inherited
delegate( events ) → EmitterMixinDelegateChain
module:engine/view/renderer~Renderer#delegate
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
andemitterC
along withdata
:emitterA.fire( 'eventX', data );
and
eventY
is delegated (fired by)emitterC
along withdata
:emitterA.fire( 'eventY', data );
Parameters
events : Array<string>
Event names that will be delegated to another emitter.
Returns
-
inherited
fire( eventOrInfo, args ) → GetEventInfo<TEvent>[ 'return' ]
module:engine/view/renderer~Renderer#fire
Fires an event, executing all callbacks registered for it.
The first parameter passed to callbacks is an
EventInfo
object, followed by the optionalargs
provided in thefire()
method call.Type parameters
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 theevt.return
's property (the event info is the first param of every callback).
-
inherited
listenTo( emitter, event, callback, [ options ] ) → void
module:engine/view/renderer~Renderer#listenTo:BASE_EMITTER
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
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
-
markToSync( type, node ) → void
module:engine/view/renderer~Renderer#markToSync
Marks a view node to be updated in the DOM by
render()
.Note that only view nodes whose parents have corresponding DOM elements need to be marked to be synchronized.
Parameters
type : ChangeType
Type of the change.
node : Node
ViewNode to be marked.
Returns
void
Related:
-
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
-
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
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
-
Registers a callback function to be executed on the next time the event is fired only. This is similar to calling
on
followed byoff
in the callback.Type parameters
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
-
render() → void
module:engine/view/renderer~Renderer#render
Renders all buffered changes (
markedAttributes
,markedChildren
andmarkedTexts
) and the current view selection (if needed) to the DOM by applying a minimal set of changes to it.Renderer tries not to break the text composition (e.g. IME) and x-index of the selection, so it does as little as it is needed to update the DOM.
Renderer also handles fillers. Especially, it checks if the inline filler is needed at the selection position and adds or removes it. To prevent breaking text composition inline filler will not be removed as long as the selection is in the text node which needed it at first.
Returns
void
-
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 thatfoo.set( 'bar', 1 )
may be slightly slower thanfoo.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
-
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 thatfoo.set( 'bar', 1 )
may be slightly slower thanfoo.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 : Renderer[ K ]
The property's value.
Returns
void
-
inherited
stopDelegating( [ event ], [ emitter ] ) → void
module:engine/view/renderer~Renderer#stopDelegating
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 ofevent
to all emitters.
Returns
void
-
inherited
stopListening( [ emitter ], [ event ], [ callback ] ) → void
module:engine/view/renderer~Renderer#stopListening:BASE_STOP
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 fromemitter
.[ callback ] : Function
(Requires the
event
) The function to be removed from the call list for the givenevent
.
Returns
void
-
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' | 'render' | 'selection' | 'isFocused' | 'isSelecting' | 'isComposing' | 'domDocuments' | 'domConverter' | 'markedAttributes' | 'markedChildren' | 'markedTexts' | 'markToSync'>
Observable properties to be unbound. All the bindings will be released if no properties are provided.
Returns
void
-
private
_diffNodeLists( actualDomChildren, expectedDomChildren ) → Array<DiffResult>
module:engine/view/renderer~Renderer#_diffNodeLists
Shorthand for diffing two arrays or node lists of DOM nodes.
Parameters
actualDomChildren : Array<Node> | NodeList
Actual DOM children
expectedDomChildren : Array<Node> | NodeList
Expected DOM children.
Returns
Array<DiffResult>
The list of actions based on the
diff
function.
-
private
_domSelectionNeedsUpdate( domSelection ) → boolean
module:engine/view/renderer~Renderer#_domSelectionNeedsUpdate
Checks whether a given DOM selection needs to be updated.
Parameters
domSelection : Selection
The DOM selection to check.
Returns
boolean
-
private
_fakeSelectionNeedsUpdate( domRoot ) → boolean
module:engine/view/renderer~Renderer#_fakeSelectionNeedsUpdate
Checks whether the fake selection needs to be updated.
Parameters
domRoot : HTMLElement
A valid DOM root where a new fake selection container should be added.
Returns
boolean
-
private
_findUpdateActions( actions, actualDom, expectedDom, comparator ) → Array<DiffResult | 'update'>
module:engine/view/renderer~Renderer#_findUpdateActions
Finds DOM nodes that were replaced with the similar nodes (same tag name) in the view. All nodes are compared within one
insert
/delete
action group, for example:Actual DOM: <p><b>Foo</b>Bar<i>Baz</i><b>Bax</b></p> Expected DOM: <p>Bar<b>123</b><i>Baz</i><b>456</b></p> Input actions: [ insert, insert, delete, delete, equal, insert, delete ] Output actions: [ insert, replace, delete, equal, replace ]
Parameters
actions : Array<DiffResult>
Actions array which is a result of the
diff
function.actualDom : Array<Node> | NodeList
Actual DOM children
expectedDom : Array<Node>
Expected DOM children.
comparator : ( Node, Node ) => boolean
A comparator function that should return
true
if the given node should be reused (either by the update of a text node data or an element children list for similar elements).
Returns
Array<DiffResult | 'update'>
Actions array modified with the
update
actions.
-
private
_getInlineFillerPosition() → Position
module:engine/view/renderer~Renderer#_getInlineFillerPosition
Gets the position of the inline filler based on the current selection. Here, we assume that we know that the filler is needed and is at the selection position, and, since it is needed, it is somewhere at the selection position.
Note: The filler position cannot be restored based on the filler's DOM text node, because when this method is called (before rendering), the bindings will often be broken. View-to-DOM bindings are only dependable after rendering.
Returns
-
private
_isSelectionInInlineFiller() → boolean
module:engine/view/renderer~Renderer#_isSelectionInInlineFiller
Returns
true
if the selection has not left the inline filler's text node. If it istrue
, it means that the filler had been added for a reason and the selection did not leave the filler's text node. For example, the user can be in the middle of a composition so it should not be touched.Returns
boolean
true
if the inline filler and selection are in the same place.
-
private
_markDescendantTextToSync( viewNode ) → void
module:engine/view/renderer~Renderer#_markDescendantTextToSync
Marks text nodes to be synchronized.
If a text node is passed, it will be marked. If an element is passed, all descendant text nodes inside it will be marked.
Parameters
viewNode : undefined | Node
View node to sync.
Returns
void
-
private
_needsInlineFillerAtSelection() → boolean
module:engine/view/renderer~Renderer#_needsInlineFillerAtSelection
Checks if the inline filler should be added.
Returns
boolean
true
if the inline filler should be added.
-
-
-
-
Checks if attribute list needs to be updated and possibly updates it.
Parameters
viewElement : Element
The view element to update.
Returns
void
-
private
_updateChildren( viewElement, options = { options.inlineFillerPosition } ) → void
module:engine/view/renderer~Renderer#_updateChildren
Checks if elements child list needs to be updated and possibly updates it.
Note that on Android, to reduce the risk of composition breaks, it tries to update data of an existing child text nodes instead of replacing them completely.
Parameters
viewElement : Element
View element to update.
options : object
-
Properties
options.inlineFillerPosition : null | Position
The position where the inline filler should be rendered.
Returns
void
-
private
_updateChildrenMappings( viewElement ) → void
module:engine/view/renderer~Renderer#_updateChildrenMappings
Updates mappings of view element's children.
Children that were replaced in the view structure by similar elements (same tag name) are treated as 'replaced'. This means that their mappings can be updated so the new view elements are mapped to the existing DOM elements. Thanks to that these elements do not need to be re-rendered completely.
Parameters
viewElement : Element
The view element whose children mappings will be updated.
Returns
void
-
private
_updateDomSelection( domRoot ) → void
module:engine/view/renderer~Renderer#_updateDomSelection
Updates the DOM selection.
Parameters
domRoot : HTMLElement
A valid DOM root where the DOM selection should be rendered.
Returns
void
-
private
_updateElementMappings( viewElement, domElement ) → void
module:engine/view/renderer~Renderer#_updateElementMappings
Updates mappings of a given view element.
Parameters
viewElement : Element
The view element whose mappings will be updated.
domElement : HTMLElement
The DOM element representing the given view element.
Returns
void
-
private
_updateFakeSelection( domRoot ) → void
module:engine/view/renderer~Renderer#_updateFakeSelection
Updates the fake selection.
Parameters
domRoot : HTMLElement
A valid DOM root where the fake selection container should be added.
Returns
void
-
-
-
private
_updateText( viewText, options = { [options.inlineFillerPosition] } ) → void
module:engine/view/renderer~Renderer#_updateText
-
private
_updateTextNode( domText, expectedText ) → void
module:engine/view/renderer~Renderer#_updateTextNode
Checks if text needs to be updated and possibly updates it by removing and inserting only parts of the data from the existing text node to reduce impact on the IME composition.
Parameters
domText : Text
DOM text node to update.
expectedText : string
The expected data of a text node.
Returns
void
-
private
_updateTextNodeInternal( domText, expectedText ) → void
module:engine/view/renderer~Renderer#_updateTextNodeInternal
Part of the
_updateTextNode
method extracted for easier testing.Parameters
domText : Text
expectedText : string
Returns
void
Events
-
change:isComposing( eventInfo, name, value, oldValue )
module:engine/view/renderer~Renderer#event:change:isComposing
Fired when the
isComposing
property changed value.Parameters
eventInfo : EventInfo
An object containing information about the fired event.
name : string
Name of the changed property (
isComposing
).value : boolean
New value of the
isComposing
property with given key ornull
, if operation should remove property.oldValue : boolean
Old value of the
isComposing
property with given key ornull
, if property was not set before.
-
change:isFocused( eventInfo, name, value, oldValue )
module:engine/view/renderer~Renderer#event:change:isFocused
Fired when the
isFocused
property changed value.Parameters
eventInfo : EventInfo
An object containing information about the fired event.
name : string
Name of the changed property (
isFocused
).value : boolean
New value of the
isFocused
property with given key ornull
, if operation should remove property.oldValue : boolean
Old value of the
isFocused
property with given key ornull
, if property was not set before.
-
change:isSelecting( eventInfo, name, value, oldValue )
module:engine/view/renderer~Renderer#event:change:isSelecting
Fired when the
isSelecting
property changed value.Parameters
eventInfo : EventInfo
An object containing information about the fired event.
name : string
Name of the changed property (
isSelecting
).value : boolean
New value of the
isSelecting
property with given key ornull
, if operation should remove property.oldValue : boolean
Old value of the
isSelecting
property with given key ornull
, if property was not set before.
-
inherited
change:{property}( eventInfo, name, value, oldValue )
module:engine/view/renderer~Renderer#event:change:{property}
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.
-
set:isComposing( eventInfo, name, value, oldValue )
module:engine/view/renderer~Renderer#event:set:isComposing
Fired when the
isComposing
property is going to be set but is not set yet (before thechange
event is fired).Parameters
eventInfo : EventInfo
An object containing information about the fired event.
name : string
Name of the changed property (
isComposing
).value : boolean
New value of the
isComposing
property with given key ornull
, if operation should remove property.oldValue : boolean
Old value of the
isComposing
property with given key ornull
, if property was not set before.
-
set:isFocused( eventInfo, name, value, oldValue )
module:engine/view/renderer~Renderer#event:set:isFocused
Fired when the
isFocused
property is going to be set but is not set yet (before thechange
event is fired).Parameters
eventInfo : EventInfo
An object containing information about the fired event.
name : string
Name of the changed property (
isFocused
).value : boolean
New value of the
isFocused
property with given key ornull
, if operation should remove property.oldValue : boolean
Old value of the
isFocused
property with given key ornull
, if property was not set before.
-
set:isSelecting( eventInfo, name, value, oldValue )
module:engine/view/renderer~Renderer#event:set:isSelecting
Fired when the
isSelecting
property is going to be set but is not set yet (before thechange
event is fired).Parameters
eventInfo : EventInfo
An object containing information about the fired event.
name : string
Name of the changed property (
isSelecting
).value : boolean
New value of the
isSelecting
property with given key ornull
, if operation should remove property.oldValue : boolean
Old value of the
isSelecting
property with given key ornull
, if property was not set before.
-
inherited
set:{property}( eventInfo, name, value, oldValue )
module:engine/view/renderer~Renderer#event:set:{property}
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.
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