topical media & game development
#graphic-flex-image-effects-04-Flex-CopyAlphaChannelTest.ax
#graphic-flex-image-effects-04-Flex-CopyAlphaChannelTest.ax
[swf]
[flash]
flex
package {
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.BitmapDataChannel;
import flash.display.Shape;
import flash.filters.BlurFilter;
import flash.geom.Point;
[SWF(width=600, height=300, backgroundColor=0x000000)]
Demonstrates how BitmapData's copyChannel() can be used to copy alpha information into an image.
public class @ax-graphic-flex-image-effects-04-Flex-CopyAlphaChannelTest extends graphic_flex_image_effects_04_Flex_AbstractImageLoader {
Constructor. Passes path of image to load to super.
public function @ax-graphic-flex-image-effects-04-Flex-CopyAlphaChannelTest() {
super("graphic-flex-image-effects-04-assets-goat.jpg");
}
Run after the image loads in super class. This creates a shape and uses the shape's data as an alpha
mask for the loaded image.
override protected function runPostImageLoad():void {
var bitmapData:BitmapData = _loadedBitmap.bitmapData;
var width:Number = bitmapData.width;
var height:Number = bitmapData.height;
// create new 32 bit bitmap data with alpha channel
var bitmapCopy:BitmapData = new BitmapData(width, height, true, 0x00000000);
// copy in loaded image so that it has alpha data
bitmapCopy.copyPixels(bitmapData, bitmapData.rect, new Point());
bitmapData.dispose();
// draws mask shape using drawing API
var shape:Shape = createMask(width, height);
// draw shape into bitmap data so that its alpha channel can be copied
var shapeBitmapData:BitmapData = new BitmapData(width, height, true, 0x00000000);
shapeBitmapData.draw(shape);
// copy shape's alpha data into loaded image
bitmapCopy.copyChannel(
shapeBitmapData,
shapeBitmapData.rect,
new Point(),
BitmapDataChannel.ALPHA,
BitmapDataChannel.ALPHA
);
_loadedBitmap.bitmapData = bitmapCopy;
_loadedBitmap.x = width;
addChild(_loadedBitmap);
}
Create a mask shape of the specified width and height.
parameter: width The pixel width to draw the mask.
parameter: height The pixel height to draw the mask.
private function createMask(width:Number, height:Number):Shape {
var shape:Shape = new Shape();
shape.graphics.beginFill(0xFFFFFF);
shape.graphics.drawEllipse(30, 30, width-60, height-60);
shape.graphics.endFill();
shape.filters = [new BlurFilter(50, 50)];
addChild(shape);
return shape;
}
}
}
(C) Æliens
04/09/2009
You may not copy or print any of this material without explicit permission of the author or the publisher.
In case of other copyright issues, contact the author.
