mx.effects.Zoom (Flex™ 2 Language Reference)

Package	mx.effects
Class	public class Zoom
Inheritance	Zoom TweenEffect Effect EventDispatcher Object

The Zoom effect zooms the object in or out on a center point.

When you apply a Zoom effect to text rendered using a system font, Flex scales the text between whole point sizes. While you do not have to use embedded fonts when you apply a Zoom effect to text, the Zoom will appear smoother when you apply it to embedded fonts.

Note: The Zoom effect does not work when the Container.autoLayout property is false.

MXML Syntax expanded

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The <mx:Zoom> tag inherits all of the tag attributes of its superclass, and adds the following tag attributes:

  <mx:Zoom
    id="ID"
    captureRollEvents="false|true"
    originX="Calculated"
    originY="Calculated"
    zoomWidthFrom="0.01"
    zoomWidthTo="1.0"
    zoomHeightFrom="0.01"
    zoomHeightTo="1.0"
  />

View the examples.

Public Properties

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	Property		Defined by
		captureRollEvents : Boolean If `true`, prevents Flex from dispatching the `rollOut` and `rollOver` events if the mouse has not moved.	Zoom
		className : String The name of the effect class, such as `"Fade"`.	Effect
		constructor : Object A reference to the class object or constructor function for a given object instance.	Object
		customFilter : EffectTargetFilter Specifies a custom filter object, of type EffectTargetFilter, used by the effect to determine the targets on which to play the effect.	Effect
		duration : Number Duration of the effect in milliseconds.	Effect
		easingFunction : Function = null The easing function for the animation.	TweenEffect
		filter : String Specifies an algorithm for filtering targets for an effect.	Effect
		instanceClass : Class An object of type Class that specifies the effect instance class class for this effect class.	Effect
		isPlaying : Boolean A read-only flag which is true if any instances of the effect are currently playing, and false if none are.	Effect
		originX : Number Number that represents the x-position of the zoom origin when the effect target is in a container that supports absolute positioning, such as the Canvas container.	Zoom
		originY : Number Number that represents the y-position of the zoom origin when the effect target is in a container that supports absolute positioning, such as the Canvas container.	Zoom
		prototype : Object [static] A reference to the prototype object of a class or function object.	Object
		relevantProperties : Array An Array of property names to use when performing filtering.	Effect
		relevantStyles : Array An Array of style names to use when performing filtering.	Effect
		repeatCount : int = 1 Number of times to repeat the effect.	Effect
		repeatDelay : int = 0 Amount of time, in milliseconds, to wait before repeating the effect.	Effect
		startDelay : int = 0 Amount of time, in milliseconds, to wait before starting the effect.	Effect
		suspendBackgroundProcessing : Boolean = false If `true`, blocks all background processing while the effect is playing.	Effect
		target : Object The UIComponent object to which this effect is applied.	Effect
		targets : Array An Array of UIComponent objects that are targets for the effect.	Effect
		zoomHeightFrom : Number Number that represents the scale at which to start the height zoom, as a percent between 0.01 and 1.0.	Zoom
		zoomHeightTo : Number Number that represents the scale at which to complete the height zoom, as a percent between 0.01 and 1.0.	Zoom
		zoomWidthFrom : Number Number that represents the scale at which to start the width zoom, as a percent between 0.01 and 1.0.	Zoom
		zoomWidthTo : Number Number that represents the scale at which to complete the width zoom, as a percent between 0.01 and 1.0.	Zoom

Public Methods

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	Method		Defined by
		Zoom(target:Object = null) Constructor.	Zoom
		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
		captureStartValues():void Captures the current values of the relevant properties on the effect's targets.	Effect
		createInstance(target:Object = null):EffectInstance Creates a single effect instance and initializes it.	Effect
		createInstances(targets:Array = null):Array Takes an Array of target objects and invokes the `createInstance()` method on each target.	Effect
		dispatchEvent(event:Event):Boolean Dispatches an event into the event flow.	EventDispatcher
		end(effectInstance:EffectInstance = null):void Interrupts an effect that is currently playing, and jumps immediately to the end of the effect.	Effect
		getAffectedProperties():Array Returns an Array of Strings, where each String is the name of a property that is changed by this effect.	Effect
		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
		pause():void Pauses the effect until you call the `resume()` method.	Effect
		play(targets:Array = null, playReversedFromEnd:Boolean = false):Array Begins playing the effect.	Effect
		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
		resume():void Resumes the effect after it has been paused by a call to the `pause()` method.	Effect
		reverse():void Plays the effect in reverse, if the effect is currently playing, starting from the current position of the effect.	Effect
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Sets the availability of a dynamic property for loop operations.	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

	Method	Defined by
		applyValueToTarget(target:Object, property:String, value:*, props:Object):void Used internally by the Effect infrastructure.	Effect
		effectEndHandler(event:EffectEvent):void Called when an effect instance has finished playing.	Effect
		effectStartHandler(event:EffectEvent):void This method is called when the effect instance starts playing.	Effect
		filterInstance(propChanges:Array, targ:Object):Boolean Determines the logic for filtering out an effect instance.	Effect
		getValueFromTarget(target:Object, property:String):* Called by the `captureStartValues()` method to get the value of a property from the target.	Effect
		initInstance(instance:EffectInstance):void Copies properties of the effect to the effect instance.	Effect
		tweenEventHandler(event:TweenEvent):void Called when the TweenEffect dispatches a TweenEvent.	TweenEffect

Summary	Defined by
effectEnd	Dispatched when the effect finishes playing, either when the effect finishes playing or when the effect has been interrupted by a call to the `end()` method.	Effect
effectStart	Dispatched when the effect starts playing.	Effect
tweenEnd	Dispatched when the tween effect ends.	TweenEffect
tweenStart	Dispatched when the tween effect starts, which corresponds to the first call to the `onTweenUpdate()` method.	TweenEffect
tweenUpdate	Dispatched every time the tween effect updates the target.	TweenEffect

Property detail

captureRollEvents

property

public var captureRollEvents:Boolean

If true, prevents Flex from dispatching the rollOut and rollOver events if the mouse has not moved. Set this property to true when you use the Zoom effect to toggle the effect target between a big and small size.

For example, you use the rollOverEffect to trigger the Zoom effect to reduce the size of the target. As the target shrinks, the mouse pointer is no longer over the target, triggering a rollOut event, and the corresponding rollOutEffect. By setting the captureRollEvents property to true, you prevent Flex from dispatching the rollOut event unless it occurs because you moved the mouse.

The default value is false.

originX

property

public var originX:Number

Number that represents the x-position of the zoom origin when the effect target is in a container that supports absolute positioning, such as the Canvas container. The zoom origin is the position on the target around which the Zoom effect is centered.

The value must be between 0 and the width of the target component.

The default value is target.width / 2, which is the center of the target.

originY

property

public var originY:Number

Number that represents the y-position of the zoom origin when the effect target is in a container that supports absolute positioning, such as the Canvas container. The zoom origin is the position on the target around which the Zoom effect is centered.

The value must be between 0 and the height of the target component.

The default value is target.height / 2, which is the center of the target.

zoomHeightFrom

property

public var zoomHeightFrom:Number

Number that represents the scale at which to start the height zoom, as a percent between 0.01 and 1.0. The default value is 0.01, which is very small.

zoomHeightTo

property

public var zoomHeightTo:Number

Number that represents the scale at which to complete the height zoom, as a percent between 0.01 and 1.0. The default value is 1.0, which is the object's normal size.

zoomWidthFrom

property

public var zoomWidthFrom:Number

Number that represents the scale at which to start the width zoom, as a percent between 0.01 and 1.0. The default value is 0.01, which is very small.

zoomWidthTo

property

public var zoomWidthTo:Number

Number that represents the scale at which to complete the width zoom, as a percent between 0.01 and 1.0. The default value is 1.0, which is the object's normal size.

Constructor detail

Zoom

()

constructor

public function Zoom(target:Object = null)

Constructor.

Parameters

target:Object (default = null) — The Object to animate with this effect.

Examples

ZoomEffectExample

<?xml version="1.0" encoding="utf-8"?>
<!-- Simple example to demonstrate the Zoom effect. -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

    <mx:Script>
        <![CDATA[        
            import flash.events.MouseEvent;
        
            public function doZoom(event:MouseEvent):void {
                if (zoomAll.isPlaying) {
                    zoomAll.reverse();
                }
                else {
                    // If this is a ROLL_OUT event, play the effect backwards. 
                    // If this is a ROLL_OVER event, play the effect forwards.
                    zoomAll.play([event.target], event.type == MouseEvent.ROLL_OUT ? true : false);
                }
            }
        ]]>    
    </mx:Script>

    <mx:Zoom id="zoomAll" zoomWidthTo="1" zoomHeightTo="1" zoomWidthFrom=".5" zoomHeightFrom=".5"  />
    
    <mx:Panel title="Zoom Effect Example" width="95%" height="95%" horizontalAlign="center"
        paddingTop="5" paddingLeft="10" paddingRight="10" paddingBottom="5">

        <mx:Text width="100%" color="blue"
            text="Move the mouse over the image to enlarge it. Move the mouse off of the image to shrink it."/>

        <mx:Image id="img"
            source="@Embed(source='assets/Nokia_6630.png')"
            scaleX=".5" scaleY=".5"
            rollOver="doZoom(event)"
            rollOut="doZoom(event)"/>

    </mx:Panel>
</mx:Application>

Comments

riza232423423 said on Jun 6, 2008 at 4:55 AM :

The code example will fail where for example you have two images side by side, all using the same rollOver and rollOut handler. If the user rolls over the second image while the rollOut effect for the first image is still playing, the code reverses what's happening to the first image (so it stops shrinking, expands and then stays large).
The solution is to always check the mouse event target matches the target currently being changed with the effect (see code below):

public function doZoom(event:MouseEvent):void {
if (zoomAll.isPlaying && zoomAll.target === event.target) {
zoomAll.reverse();
} else {
zoomAll.play([event.target], event.type == MouseEvent.ROLL_OUT ? true : false);
}
}

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