Adobe® Flex® 4 Language Reference
Hide Packages and Classes List |  Packages  |  Classes  |  Index  |  Appendixes
flash.display 
Bitmap 
Packageflash.display
Classpublic class Bitmap
InheritanceBitmap Inheritance DisplayObject Inheritance EventDispatcher Inheritance Object
Subclasses FlexBitmap

Language Version: ActionScript 3.0
Runtime Versions: Flash Player 9, AIR 1.0

The Bitmap class represents display objects that represent bitmap images. These can be images that you load with the flash.display.Loader class, or they can be images that you create with the Bitmap() constructor.

The Bitmap() constructor allows you to create a Bitmap object that contains a reference to a BitmapData object. After you create a Bitmap object, use the addChild() or addChildAt() method of the parent DisplayObjectContainer instance to place the bitmap on the display list.

A Bitmap object can share its BitmapData reference among several Bitmap objects, independent of translation or rotation properties. Because you can create multiple Bitmap objects that reference the same BitmapData object, multiple display objects can use the same complex BitmapData object without incurring the memory overhead of a BitmapData object for each display object instance.

A BitmapData object can be drawn to the screen by a Bitmap object in one of two ways: by using the vector renderer as a fill-bitmap shape, or by using a faster pixel-copying routine. The pixel-copying routine is substantially faster than the vector renderer, but the Bitmap object must meet certain conditions to use it:

  • No stretching, rotation, or skewing can be applied to the Bitmap object.
  • No color transform can be applied to the Bitmap object.
  • No blend mode can be applied to the Bitmap object.
  • No clipping can be done through mask layers or setMask() methods.
  • The image itself cannot be a mask.
  • The destination coordinates must be on a whole pixel boundary.

If you load a Bitmap object from a domain other than that of the Loader object used to load the image, and there is no URL policy file that permits access to the domain of the Loader object, then a script in that domain cannot access the Bitmap object or its properties and methods. For more information, see the following:

  • The security chapter in the Programming ActionScript 3.0 book and the latest comments on LiveDocs
  • The security chapter in the Programming ActionScript 3.0 book and the latest comments on LiveDocs
  • The Flash Player Developer Center Topic: Security

Note: The Bitmap class is not a subclass of the InteractiveObject class, so it cannot dispatch mouse events. However, you can use the addEventListener() method of the display object container that contains the Bitmap object.

View the examples

See also



Public Properties
 PropertyDefined By
 InheritedaccessibilityProperties : AccessibilityProperties
The current accessibility options for this display object.
DisplayObject
 Inheritedalpha : Number
Indicates the alpha transparency value of the object specified.
DisplayObject
  bitmapData : BitmapData
The BitmapData object being referenced.
Bitmap
 InheritedblendMode : String
A value from the BlendMode class that specifies which blend mode to use.
DisplayObject
 InheritedblendShader : Shader
[write-only] Sets a shader that is used for blending the foreground and background.
DisplayObject
 InheritedcacheAsBitmap : Boolean
If set to true, Flash Player or Adobe AIR caches an internal bitmap representation of the display object.
DisplayObject
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
 Inheritedfilters : Array
An indexed array that contains each filter object currently associated with the display object.
DisplayObject
 Inheritedheight : Number
Indicates the height of the display object, in pixels.
DisplayObject
 InheritedloaderInfo : LoaderInfo
[read-only] Returns a LoaderInfo object containing information about loading the file to which this display object belongs.
DisplayObject
 Inheritedmask : DisplayObject
The calling display object is masked by the specified mask object.
DisplayObject
 InheritedmouseX : Number
[read-only] Indicates the x coordinate of the mouse position, in pixels.
DisplayObject
 InheritedmouseY : Number
[read-only] Indicates the y coordinate of the mouse position, in pixels.
DisplayObject
 Inheritedname : String
Indicates the instance name of the DisplayObject.
DisplayObject
 InheritedopaqueBackground : Object
Specifies whether the display object is opaque with a certain background color.
DisplayObject
 Inheritedparent : DisplayObjectContainer
[read-only] Indicates the DisplayObjectContainer object that contains this display object.
DisplayObject
  pixelSnapping : String
Controls whether or not the Bitmap object is snapped to the nearest pixel.
Bitmap
 Inheritedprototype : Object
[static] A reference to the prototype object of a class or function object.
Object
 Inheritedroot : DisplayObject
[read-only] For a display object in a loaded SWF file, the root property is the top-most display object in the portion of the display list's tree structure represented by that SWF file.
DisplayObject
 Inheritedrotation : Number
Indicates the rotation of the DisplayObject instance, in degrees, from its original orientation.
DisplayObject
 InheritedrotationX : Number
Indicates the x-axis rotation of the DisplayObject instance, in degrees, from its original orientation relative to the 3D parent container.
DisplayObject
 InheritedrotationY : Number
Indicates the y-axis rotation of the DisplayObject instance, in degrees, from its original orientation relative to the 3D parent container.
DisplayObject
 InheritedrotationZ : Number
Indicates the z-axis rotation of the DisplayObject instance, in degrees, from its original orientation relative to the 3D parent container.
DisplayObject
 Inheritedscale9Grid : Rectangle
The current scaling grid that is in effect.
DisplayObject
 InheritedscaleX : Number
Indicates the horizontal scale (percentage) of the object as applied from the registration point.
DisplayObject
 InheritedscaleY : Number
Indicates the vertical scale (percentage) of an object as applied from the registration point of the object.
DisplayObject
 InheritedscaleZ : Number
Indicates the depth scale (percentage) of an object as applied from the registration point of the object.
DisplayObject
 InheritedscrollRect : Rectangle
The scroll rectangle bounds of the display object.
DisplayObject
  smoothing : Boolean
Controls whether or not the bitmap is smoothed when scaled.
Bitmap
 Inheritedstage : Stage
[read-only] The Stage of the display object.
DisplayObject
 Inheritedtransform : flash.geom:Transform
An object with properties pertaining to a display object's matrix, color transform, and pixel bounds.
DisplayObject
 Inheritedvisible : Boolean
Whether or not the display object is visible.
DisplayObject
 Inheritedwidth : Number
Indicates the width of the display object, in pixels.
DisplayObject
 Inheritedx : Number
Indicates the x coordinate of the DisplayObject instance relative to the local coordinates of the parent DisplayObjectContainer.
DisplayObject
 Inheritedy : Number
Indicates the y coordinate of the DisplayObject instance relative to the local coordinates of the parent DisplayObjectContainer.
DisplayObject
 Inheritedz : Number
Indicates the z coordinate position along the z-axis of the DisplayObject instance relative to the 3D parent container.
DisplayObject
Public Methods
 MethodDefined By
  
Bitmap(bitmapData:BitmapData = null, pixelSnapping:String = "auto", smoothing:Boolean = false)
Initializes a Bitmap object to refer to the specified BitmapData object.
Bitmap
 Inherited
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
 Inherited
Dispatches an event into the event flow.
EventDispatcher
 Inherited
getBounds(targetCoordinateSpace:DisplayObject):Rectangle
Returns a rectangle that defines the area of the display object relative to the coordinate system of the targetCoordinateSpace object.
DisplayObject
 Inherited
getRect(targetCoordinateSpace:DisplayObject):Rectangle
Returns a rectangle that defines the boundary of the display object, based on the coordinate system defined by the targetCoordinateSpace parameter, excluding any strokes on shapes.
DisplayObject
 Inherited
Converts the point object from the Stage (global) coordinates to the display object's (local) coordinates.
DisplayObject
 Inherited
Converts a two-dimensional point from the Stage (global) coordinates to a three-dimensional display object's (local) coordinates.
DisplayObject
 Inherited
Checks whether the EventDispatcher object has any listeners registered for a specific type of event.
EventDispatcher
 Inherited
Indicates whether an object has a specified property defined.
Object
 Inherited
Evaluates the bounding box of the display object to see if it overlaps or intersects with the bounding box of the obj display object.
DisplayObject
 Inherited
hitTestPoint(x:Number, y:Number, shapeFlag:Boolean = false):Boolean
Evaluates the display object to see if it overlaps or intersects with the point specified by the x and y parameters.
DisplayObject
 Inherited
Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.
Object
 Inherited
Converts a three-dimensional point of the three-dimensional display object's (local) coordinates to a two-dimensional point in the Stage (global) coordinates.
DisplayObject
 Inherited
Converts the point object from the display object's (local) coordinates to the Stage (global) coordinates.
DisplayObject
 Inherited
Indicates whether the specified property exists and is enumerable.
Object
 Inherited
removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void
Removes a listener from the EventDispatcher object.
EventDispatcher
 Inherited
Sets the availability of a dynamic property for loop operations.
Object
 Inherited
Returns the string representation of this object, formatted according to locale-specific conventions.
Object
 Inherited
Returns the string representation of the specified object.
Object
 Inherited
Returns the primitive value of the specified object.
Object
 Inherited
Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.
EventDispatcher
Events
 Event Summary Defined By
 Inherited[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.EventDispatcher
 InheritedDispatched when a display object is added to the display list.DisplayObject
 InheritedDispatched when a display object is added to the on stage display list, either directly or through the addition of a sub tree in which the display object is contained.DisplayObject
 Inherited[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.EventDispatcher
 Inherited[broadcast event] Dispatched when the playhead is entering a new frame.DisplayObject
 Inherited[broadcast event] Dispatched when the playhead is exiting the current frame.DisplayObject
 Inherited[broadcast event] Dispatched after the constructors of frame display objects have run but before frame scripts have run.DisplayObject
 InheritedDispatched when a display object is about to be removed from the display list.DisplayObject
 InheritedDispatched when a display object is about to be removed from the display list, either directly or through the removal of a sub tree in which the display object is contained.DisplayObject
 Inherited[broadcast event] Dispatched when the display list is about to be updated and rendered.DisplayObject
Property Detail

bitmapData

property
bitmapData:BitmapData

Language Version: ActionScript 3.0
Runtime Versions: Flash Player 9, AIR 1.0

The BitmapData object being referenced.



Implementation
    public function get bitmapData():BitmapData
    public function set bitmapData(value:BitmapData):void

pixelSnapping

property 
pixelSnapping:String

Language Version: ActionScript 3.0
Runtime Versions: Flash Player 9, AIR 1.0

Controls whether or not the Bitmap object is snapped to the nearest pixel. The PixelSnapping class includes possible values:

  • PixelSnapping.NEVER—No pixel snapping occurs.
  • PixelSnapping.ALWAYS—The image is always snapped to the nearest pixel, independent of transformation.
  • PixelSnapping.AUTO—The image is snapped to the nearest pixel if it is drawn with no rotation or skew and it is drawn at a scale factor of 99.9% to 100.1%. If these conditions are satisfied, the bitmap image is drawn at 100% scale, snapped to the nearest pixel. Internally, this value allows the image to be drawn as fast as possible using the vector renderer.



Implementation
    public function get pixelSnapping():String
    public function set pixelSnapping(value:String):void

smoothing

property 
smoothing:Boolean

Language Version: ActionScript 3.0
Runtime Versions: Flash Player 9, AIR 1.0

Controls whether or not the bitmap is smoothed when scaled. If true, the bitmap is smoothed when scaled. If false, the bitmap is not smoothed when scaled.



Implementation
    public function get smoothing():Boolean
    public function set smoothing(value:Boolean):void
Constructor Detail

Bitmap

()Constructor
public function Bitmap(bitmapData:BitmapData = null, pixelSnapping:String = "auto", smoothing:Boolean = false)

Language Version: ActionScript 3.0
Runtime Versions: Flash Player 9, AIR 1.0

Initializes a Bitmap object to refer to the specified BitmapData object.

Parameters
bitmapData:BitmapData (default = null) — The BitmapData object being referenced.
 
pixelSnapping:String (default = "auto") — Whether or not the Bitmap object is snapped to the nearest pixel.
 
smoothing:Boolean (default = false) — Whether or not the bitmap is smoothed when scaled. For example, the following examples show the same bitmap scaled by a factor of 3, with smoothing set to false (left) and true (right):

A bitmap without smoothing.A bitmap with smoothing.

BitmapExample.as

The following example uses the BitmapExample class to load the "Image.gif" image into a DisplayObject in the default location (x = 0, y = 0). A copy of Image.gif is then placed to the right of the original, which has new colors applied to pixels that pass a test using the threshold() method. This task is accomplished using the following steps:
  1. A property url is created, which is the location and name of the image file
  2. The class constructor calls the configureAssets() method, which, in turn, calls the completeHandler() method.
  3. configureAssets() creates a Loader object, which then instantiates an event listener, which is dispatched when completeHandler() completes the image manipulation.
  4. Next, the buildChild() method creates a new instance of a URLRequest object, request, with url passed so the file name and location are known.
  5. The request object is passed to the loader.load() method, which loads the image into memory via a display object.
  6. The image is then placed on the display list, which promptly displays the image on screen at coordinates x = 0, y = 0.
  7. The completeHandler() method then performs the following tasks:
    1. Creates a second Loader object, along with a Bitmap object, which is initialized with the Loader object.
    2. Creates a second Bitmap object, duplicate, which in turn calls the duplicateImage() method, which creates a duplicate of the original image.
    3. Creates a BitmapData object, which is assigned to the duplicate object's BitmapData object.
    4. Creates a new Rectangle object initialized with the same coordinates, width, and height as the original image.
    5. Creates a new Point object, which defaults to x = 0, y = 0.
    6. Creates the following variables:
      • operation: applies the new color when the threshold value is >= the original.
      • threshold: the value against which each pixel is compared is set to light gray with an alpha of 0xCC.
      • color: the color that the pixels will be set to that pass the threshold test, which is solid yellow in this case.
      • mask: set to the exact opposite of color, (transparent blue).
      • copySource: set to false, indicating that the pixel values are not copied in the event the threshold value does not pass. This value has no meaning because the image is duplicated and only pixels that pass the threshold test are changed.
    7. Calls the threshold() method by using the preceding variables. The resulting threshold equation is as follows: if (current pixel Value & 0x000000FF) >= (0xCCCCCCCC & 0x000000FF) then set pixel to 0xFFFFFF00.

Notes:

  • You will need to compile the SWF file with "Local playback security" set to "Access local files only".
  • This example requires that a file named Image.gif be placed in the same directory as your SWF file.
  • It is recommended that you use an image up to 80 pixels wide.


package {
    import flash.display.Bitmap;
    import flash.display.BitmapData;
    import flash.display.Loader;
    import flash.display.Sprite;
    import flash.events.*;
    import flash.geom.Point;
    import flash.geom.Rectangle;
    import flash.net.URLRequest;

    public class BitmapExample extends Sprite {
        private var url:String = "Image.gif";
        private var size:uint = 80;

        public function BitmapExample() {
            configureAssets();
        }

        private function configureAssets():void {
            var loader:Loader = new Loader();
            loader.contentLoaderInfo.addEventListener(Event.COMPLETE, completeHandler);
            loader.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, ioErrorHandler);

            var request:URLRequest = new URLRequest(url);
            loader.x = size * numChildren;
            loader.load(request);
            addChild(loader);
        }

        private function duplicateImage(original:Bitmap):Bitmap {
            var image:Bitmap = new Bitmap(original.bitmapData.clone());
            image.x = size * numChildren;
            addChild(image);
            return image;
        }

        private function completeHandler(event:Event):void {
            var loader:Loader = Loader(event.target.loader);
            var image:Bitmap = Bitmap(loader.content);

            var duplicate:Bitmap = duplicateImage(image);
            var bitmapData:BitmapData = duplicate.bitmapData;
            var sourceRect:Rectangle = new Rectangle(0, 0, bitmapData.width, bitmapData.height);
            var destPoint:Point = new Point();
            var operation:String = ">=";
            var threshold:uint = 0xCCCCCCCC;
            var color:uint = 0xFFFFFF00;
            var mask:uint = 0x000000FF;
            var copySource:Boolean = true;

            bitmapData.threshold(bitmapData,
                                 sourceRect,
                                 destPoint,
                                 operation,
                                 threshold,
                                 color,
                                 mask,
                                 copySource);
        }
        
        private function ioErrorHandler(event:IOErrorEvent):void {
            trace("Unable to load image: " + url);
        }
    }
}