ViewTransitionBase

Package	spark.transitions
Class	public class ViewTransitionBase
Inheritance	ViewTransitionBase EventDispatcher Object
Subclasses	CrossFadeViewTransition, FlipViewTransition, SlideViewTransition, ZoomViewTransition

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

The ViewTransitionBase class is the base class for all view transitions. It is not intended to be used as a transition on its own. In addition to providing common convenience and helper methods used by view transitions, this class provides a default action bar transition sequence.

When a view transition is initialized, the owning view navigator sets the startView and endView properties to the views the transition animates. The navigator property is set to the view navigator.

The lifecycle of a transition is as follows:

The transition starts with the captureStartValues() method. When this method is called, the navigator is currently in the start state. At this time, the transition should capture any start values or bitmaps that it requires.
A validation pass is performed on the pending view, and the captureEndValues() method is called. At this time, the transition captures any properties or bitmaps representations from the pending view.
The prepareForPlay() method is then called, which allows the transition to perform any further preparations, such as preparing a Spark effects sequence, or positioning transient elements on the display list.
After a final validation pass, if necessary, the play() method is called by the navigator to perform the actual transition.
Prior to any animation starting, the start event is dispatched.
When a transition completes, it dispatches an end event.

Note:Create and configure view transitions in ActionScript; you cannot create them in MXML.

Public Properties

	Property		Defined By
		constructor : Object A reference to the class object or constructor function for a given object instance.	Object
		duration : Number Duration of the transition, in milliseconds.	ViewTransitionBase
		easer : IEaser The easing behavior for this transition.	ViewTransitionBase
		endView : View The view that the navigator is transitioning to, as set by the owning ViewNavigator object.	ViewTransitionBase
		navigator : ViewNavigator Reference to the owning ViewNavigator instance set by the owning ViewNavigator.	ViewTransitionBase
		startView : View The currently active view of the view navigator, as set by the owning view navigator.	ViewTransitionBase
		suspendBackgroundProcessing : Boolean When set to true, the UIComponent.suspendBackgroundProcessing() method is invoked prior to the transition playing.	ViewTransitionBase
		transitionControlsWithContent : Boolean When set to true, the primary view transition is used to transition the view navigator in its entirety, including the action bar.	ViewTransitionBase

Public Methods

	Method		Defined By
		ViewTransitionBase() Constructor.	ViewTransitionBase
		addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event.	EventDispatcher
		captureEndValues():void Called by the ViewNavigator during the preparation phase of a transition.	ViewTransitionBase
		captureStartValues():void Called by the ViewNavigator during the preparation phase of a transition.	ViewTransitionBase
		dispatchEvent(event:Event):Boolean Dispatches an event into the event flow.	EventDispatcher
		hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event.	EventDispatcher
		hasOwnProperty(name:String):Boolean Indicates whether an object has a specified property defined.	Object
		isPrototypeOf(theClass:Object):Boolean Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.	Object
		play():void Called by the ViewNavigator when the transition should begin animating.	ViewTransitionBase
		prepareForPlay():void Called by the ViewNavigator during the preparation phase of a transition.	ViewTransitionBase
		propertyIsEnumerable(name:String):Boolean Indicates whether the specified property exists and is enumerable.	Object
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object.	EventDispatcher
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Sets the availability of a dynamic property for loop operations.	Object
		toLocaleString():String Returns the string representation of this object, formatted according to locale-specific conventions.	Object
		toString():String Returns the string representation of the specified object.	Object
		valueOf():Object Returns the primitive value of the specified object.	Object
		willTrigger(type:String):Boolean Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.	EventDispatcher

Protected Methods

	Method		Defined By
		canTransitionControlBarContent():Boolean Determine if Flex can perform a transition on action bar or tab bar content independently of the views.	ViewTransitionBase
		cleanUp():void Called after the transition completes.	ViewTransitionBase
		createActionBarEffect():IEffect Called by the default prepareForPlay() implementation, this method is responsible for creating the Spark effect played on the action bar when the transition starts.	ViewTransitionBase
		createConsolidatedEffect():IEffect Called by the default prepareForPlay() implementation, this method is responsible for creating the Spark effect played to transition the entire navigator, inclusive of the control bar content, when necessary.	ViewTransitionBase
		createTabBarEffect():IEffect Called by the default prepareForPlay() implementation, this method is responsible for creating the Spark effect played on the tab bar when the transition starts.	ViewTransitionBase
		createViewEffect():IEffect Called by the default prepareForPlay() implementation, this method is responsible for creating the Spark effect played on the current and next view when the transition starts.	ViewTransitionBase
		getSnapshot(target:UIComponent, padding:int = 4, globalPosition:Point = null):BitmapImage Used to render snap shots of screen elements in preparation for transitioning.	ViewTransitionBase
		transitionComplete():void Called by the transition to indicate that the transition has completed.	ViewTransitionBase

Events

Click for more information on events

	Summary	Defined By
activate	[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.	EventDispatcher
deactivate	[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.	EventDispatcher
transitionEnd	Dispatched when the transition completes.	ViewTransitionBase
transitionStart	Dispatched when the transition starts.	ViewTransitionBase

Property Detail

duration

property

duration:Number

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Duration of the transition, in milliseconds. The default may vary depending on the transition but is defined in ViewTransitionBase as 250 ms.

Implementation
public function get duration():Number
public function set duration(value:Number):void

easer

property

easer:IEaser

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

The easing behavior for this transition. The IEaser object is generally propagated to the IEffect instance managing the actual transition animation.

The default value is Sine(.5);.

Implementation
public function get easer():IEaser
public function set easer(value:IEaser):void

Related API Elements

spark.effects.easing

endView

property

endView:View

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

The view that the navigator is transitioning to, as set by the owning ViewNavigator object. This property can be null.

The default value is null.

Implementation
public function get endView():View
public function set endView(value:View):void

navigator

property

navigator:ViewNavigator

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Reference to the owning ViewNavigator instance set by the owning ViewNavigator.

The default value is null.

Implementation
public function get navigator():ViewNavigator
public function set navigator(value:ViewNavigator):void

startView

property

startView:View

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

The currently active view of the view navigator, as set by the owning view navigator. This property can be null.

Implementation
public function get startView():View
public function set startView(value:View):void

suspendBackgroundProcessing

property

suspendBackgroundProcessing:Boolean

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

When set to true, the UIComponent.suspendBackgroundProcessing() method is invoked prior to the transition playing. This disables Flex's layout manager and improving performance. Upon completion of the transition, the layout manager function is restored by a call to the UIComponent.resumeBackgroundProcessing() method.

The default value is false.

Implementation
public function get suspendBackgroundProcessing():Boolean
public function set suspendBackgroundProcessing(value:Boolean):void

Related API Elements

mx.core.UIComponent.suspendBackgroundProcessing()
mx.core.UIComponent.resumeBackgroundProcessing()

transitionControlsWithContent

property

transitionControlsWithContent:Boolean

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

When set to true, the primary view transition is used to transition the view navigator in its entirety, including the action bar. Specific transitions for the action bar are not performed. Because the tab bar is associated with the entire application, and not a view, view transitions do not affect it.

Note that even when set to false, there are cases where its not feasible to transition the action bar. For example, when the action bar does not exist in one of the two views, or if the action bar changes size.

The default value is false.

Implementation
public function get transitionControlsWithContent():Boolean
public function set transitionControlsWithContent(value:Boolean):void

Constructor Detail

ViewTransitionBase

()

Constructor

public function ViewTransitionBase()

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Constructor.

Method Detail

canTransitionControlBarContent

()

method

protected function canTransitionControlBarContent():Boolean

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Determine if Flex can perform a transition on action bar or tab bar content independently of the views.

Flex cannot perform a transition on the control bars independently:

If the containing view navigator is a TabbedViewNavigator and its tab bar's visibility changes between views.
If the value of the view navigator's overlayControls property changes between views.
If the size or visibility of the action bar changes between views.

Returns

Boolean — false if Flex determines controls bars between views are incompatible in some way.

captureEndValues

()

method

public function captureEndValues():void

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called by the ViewNavigator during the preparation phase of a transition. It is invoked when the new view has been fully realized and validated and the action bar and tab bar content reflect the state of the new view. It is at this point that the transition can capture any values it requires from the pending view. In addition any bitmaps reflecting the state of the new view, tab bar, or action bar should be captured, if required for animation.

captureStartValues

()

method

public function captureStartValues():void

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called by the ViewNavigator during the preparation phase of a transition. It is invoked when the new view has been fully realized and validated and the action bar and tab bar content reflect the state of the new view. The transition can use this method capture any values it requires from the pending view. Any bitmaps reflecting the state of the new view, tab bar, or action bar should be captured if required for animation.

cleanUp

()

method

protected function cleanUp():void

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called after the transition completes. This method is responsible for releasing any references and temporary constructs used by the transition.

createActionBarEffect

()

method

protected function createActionBarEffect():IEffect

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called by the default prepareForPlay() implementation, this method is responsible for creating the Spark effect played on the action bar when the transition starts. This method should be overridden by subclasses if a custom action bar effect is required. By default, this method returns a basic action bar effect.

Returns

IEffect — An IEffect instance serving as the action bar effect. This effect is played by the default play() method implementation.

createConsolidatedEffect

()

method

protected function createConsolidatedEffect():IEffect

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called by the default prepareForPlay() implementation, this method is responsible for creating the Spark effect played to transition the entire navigator, inclusive of the control bar content, when necessary. This method should be overridden by subclasses. By default, this method returns null.

Returns

IEffect — An IEffect instance serving as the view transition. This effect is played by the default play() method implementation.

createTabBarEffect

()

method

protected function createTabBarEffect():IEffect

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called by the default prepareForPlay() implementation, this method is responsible for creating the Spark effect played on the tab bar when the transition starts. This method should be overridden by subclasses. By default, this returns null.

Returns

IEffect — An IEffect instance serving as the tab bar transition. This effect is played by the default play() method implementation.

createViewEffect

()

method

protected function createViewEffect():IEffect

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called by the default prepareForPlay() implementation, this method is responsible for creating the Spark effect played on the current and next view when the transition starts. This method should be overridden by subclasses. By default, this method returns null.

Returns

IEffect — An IEffect instance serving as the view transition. This effect is played by the default play() method implementation.

getSnapshot

()

method

protected function getSnapshot(target:UIComponent, padding:int = 4, globalPosition:Point = null):BitmapImage

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Used to render snap shots of screen elements in preparation for transitioning. The bitmap is returned in the form of a BitmapImage object.

The BitmapImage is in target's parent coordiantes space - it overlaps the target precisely if paranted to the same parent. When moving to a different parent, make sure to adjust the transformation of the BitmapImage to correctly account for the change in coordinate spaces. The updated value of the globalPosition parameter can be used for that.

Parameters

	`target:UIComponent` — Display object to capture.

	`padding:int` (default = `4`) — Padding around the object to be included in the BitmapImage object.

	`globalPosition:Point` (default = `null`) — When non-null, `globalPosition` will be updated with the origin of the BitmapImage in global coordiantes. When moving to a different coordinate space, this value can be used to adjust the snapshot's position so its global position on screen doesn't change.

Returns

BitmapImage — BitmapImage object representing the target.

play

()

method

public function play():void

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called by the ViewNavigator when the transition should begin animating. At this time, the transition should dispatch a start event.

prepareForPlay

()

method

public function prepareForPlay():void

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called by the ViewNavigator during the preparation phase of a transition. This method gives the transition the chance to create and configure the underlying IEffect instance, or to add any transient elements to the display list. Example transient elements include bitmap placeholders, temporary containers required during the transition, and other elements. If required, a final validation pass occurs prior to the invocation of the play() method.

If it is determined that a standard transition can be initiated, meaning one that transitions the control bars separately from the views, the default implementation of this method constructs a single Parallel effect which wraps the individual effect sequences for the view transition, the action bar transition, and the tab bar transition. This method uses the methods, createActionBarEffect(), createTabBarEffect(), and createViewEffect().

If transitionControlsWithContent is set to true, or if it is determined that the control bars cannot be transitioned independently, a single effect is created to transition the navigator in its entirety. In this case, only createConsolidatedEffect() is invoked.

transitionComplete

()

method

protected function transitionComplete():void

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Called by the transition to indicate that the transition has completed. This method dispatches the end event.

Event Detail

transitionEnd

Event

Event Object Type: mx.events.FlexEvent
property FlexEvent.type = mx.events.FlexEvent.TRANSITION_START

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Dispatched when the transition completes.

The FlexEvent.TRANSITION_START constant defines the value of the type property of the event object for a transitionStart event.

This event will only be dispatched when there are one or more relevant listeners attached to the dispatching object.

The properties of the event object have the following values:

Property	Value
`bubbles`	false
`cancelable`	false
`currentTarget`	The Object that defines the event listener that handles the event. For example, if you use `myButton.addEventListener()` to register an event listener, myButton is the value of the `currentTarget`.
`target`	The Object that dispatched the event; it is not always the Object listening for the event. Use the `currentTarget` property to always access the Object listening for the event.

transitionStart

Event

Event Object Type: mx.events.FlexEvent
property FlexEvent.type = mx.events.FlexEvent.TRANSITION_START

Language Version:

ActionScript 3.0

Product Version:

Flex 4.5

Runtime Versions:

AIR 2.5

Dispatched when the transition starts.

The FlexEvent.TRANSITION_START constant defines the value of the type property of the event object for a transitionStart event.

This event will only be dispatched when there are one or more relevant listeners attached to the dispatching object.

The properties of the event object have the following values:

Property	Value
`bubbles`	false
`cancelable`	false
`currentTarget`	The Object that defines the event listener that handles the event. For example, if you use `myButton.addEventListener()` to register an event listener, myButton is the value of the `currentTarget`.
`target`	The Object that dispatched the event; it is not always the Object listening for the event. Use the `currentTarget` property to always access the Object listening for the event.

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ViewTransitionBase - AS3 Flex

Classes x

duration

easer

endView

navigator

startView

suspendBackgroundProcessing

transitionControlsWithContent

ViewTransitionBase

canTransitionControlBarContent

captureEndValues

captureStartValues

cleanUp

createActionBarEffect

createConsolidatedEffect

createTabBarEffect

createViewEffect

getSnapshot

play

prepareForPlay

transitionComplete

transitionEnd

transitionStart