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The last statement that is marked as being different gets a reference to the Bitmap object and stores it in the variable named original just like was done in Listing 4.
As before, referencing the content property returns the Bitmap object as type DisplayObject . Therefore, it must be cast to type Bitmap before it can be used for the intended purpose of this program.
Beyond this point - no changes
Beyond this point, the two programs are identical except that the IO error handler was omitted from this program. As I explained earlier, because the imagefile is embedded in the SWF file at compile time, there is no need to worry about IO errors involving the image file at runtime.
I encourage you to run the online versions of the two programs from the web. Then copy the code from Listing 19 through Listing 21. Use that code tocreate Flex projects. Compile and run the projects. Experiment with the code, making changes, and observing the results of your changes. Makecertain that you can explain why your changes behave as they do.
I will publish a list containing links to ActionScript resources as a separate document.Search for ActionScript Resources in the Connexions search box.
Complete listings of the MXML code and the ActionScript code for the programs discussed in this lesson are provided below.
<?xml version="1.0" encoding="utf-8"?><!--
This program illustrates loading an image andmodifying the pixels in the image.
--><mx:Application
xmlns:mx="http://www.adobe.com/2006/mxml"xmlns:cc="CustomClasses.*"><cc:Driver/></mx:Application> /*Bitmap05
Provides skeleton code for creating a Bitmap object froman image file.
Explains the use of the getPixels, setPixels, and /*Bitmap06
This is an update to Bitmap05 that uses an image that isembedded in the SWF file rather than a separate
downloaded image file. This eliminates the requirementto make the following change to the configuration file
at:C:\Program Files\Adobe\Flex Builder 3\sdks\3.2.0\
frameworks\flex-config.xml<!-- Prevents SWFs from accessing the network. --><use-network>false</use-network>The behavior of this program is identical to the
behavior of Bitmap05.*********************************************************/
package CustomClasses{import flash.display.Bitmap;
import flash.display.BitmapData;import flash.geom.Rectangle;
import flash.utils.ByteArray;import mx.containers.VBox;
import mx.controls.Image;import mx.events.FlexEvent;
//====================================================//public class Driver extends VBox {private var image:Image = new Image();public function Driver(){//constructor
//Make the VBox visible.setStyle("backgroundColor",0xFFFF00);
setStyle("backgroundAlpha",1.0);[Embed("snowscene.jpg")]
var img:Class;image.load(img);
//Note that the type of completion event specified// here is different from the type of completion
// event used in Bitmap05.this.addEventListener(FlexEvent.CREATION_COMPLETE,
completeHandler);} //end constructor
//--------------------------------------------------////This handler method is executed when the VBox has
// been fully created. Note that the type of the// incoming parameter is more specific than was the
// case in Bitmap05. However, it isn't used in this// program.
private function completeHandler(event:mx.events.FlexEvent):void{
//Get and save a reference to a Bitmap object// containing the content of the image file. This
// statement is different from Bitmap05.var original:Bitmap = Bitmap(image.content);
//Everything beyond this point is identical to// Bitmap05 except that the IO error handler was
// removed. It isn't needed for an embedded image// file.//Set the width and height of the VBox object based
// on the size of the original bitmap.this.width = original.width + 10;
this.height = 3*original.height + 12;//Encapsulate the bitmap in an Image object and add// the Image object to the VBox. Display it at
// x=5 and y=0original.x = 5;
original.y = 0;var imageA:Image = new Image();
imageA.addChild(original);this.addChild(imageA);//Clone the original bitmap to create a duplicate.var duplicateB:Bitmap = new Bitmap(
original.bitmapData.clone());//Place the duplicate bitmap below the original in
// the VBox. There is a six-pixel downward shift// that I am unable to explain at this time. The
// shift produces a gap of about six pixels between// the two images.
duplicateB.x = 5;duplicateB.y = original.height;var imageB:Image = new Image();
imageB.addChild(duplicateB);this.addChild(imageB);//Modify this duplicate.
modify(duplicateB);//Clone the original bitmap to create another// duplicate.
var duplicateC:Bitmap = new Bitmap(original.bitmapData.clone());
//Place the duplicateC below the other two in the// VBox.
duplicateC.x = 5;duplicateC.y = 2*original.height;var imageC:Image = new Image();
imageC.addChild(duplicateC);this.addChild(imageC);//Modify the pixels as above to add some color to
// the image.modify(duplicateC);
//Now invert the colors in the top half of this// bitmap. Note that the magenta and green colors
// swap positions.invert(duplicateC);
} //end completeHandler//--------------------------------------------------////This method modifies the pixels in the incoming
// bitmap in a variety of ways.private function modify(bitmap:Bitmap):void{
//Get the BitmapData object from the incoming// Bitmap object.
var bitmapData:BitmapData = bitmap.bitmapData;//Process pixels using the getPixels and
// setPixels methods.//Get a rectangular array of pixels comprising// 50 columns by 8 rows in a one-dimensional
// array of bytes. The bytes are ordered in the// array as row 0, row 1, etc. Each pixel is
// represented by four consecutive bytes in ARGB// order.
var rawBytes:ByteArray = new ByteArray();rawBytes = bitmapData.getPixels(
new Rectangle(10,10,50,8));//Set the colors of the top four rows to magenta// and the color of the bottom four rows to
// green. Don't modify alpha.var cnt:uint = 1;
while(cnt<rawBytes.length){
if(cnt<rawBytes.length/2){
rawBytes[cnt]= 255;
rawBytes[cnt + 1]= 0;
rawBytes[cnt + 2]= 255;
}else{rawBytes[cnt] = 0;rawBytes[cnt + 1] = 255;rawBytes[cnt + 2] = 0;} //end if-elsecnt += 4;//Increment the counter by 4.
}//end while loop//Put the modified pixels back in the bitmapData
// object.rawBytes.position = 0;//this is critical
bitmapData.setPixels(new Rectangle(10,10,50,8),rawBytes);//Process pixels using the setPixel32 method.//Put a magenta border on the left edge and a// cyan border on the right edge. Note that the
// byte values in the 32-bit pixel are in ARGB order// and the border thickness is two pixels.
for(var row:uint = 0;row<bitmapData.height;
row++){bitmapData.setPixel32(0,row,0xFFFF00FF);
bitmapData.setPixel32(1,row,0xFFFF00FF);bitmapData.setPixel32(bitmapData.width - 1,
row,0xFF00FFFF);bitmapData.setPixel32(bitmapData.width - 2,
row,0xFF00FFFF);}//end for loop//Put a cyan border along the top edge and a
// magenta border along the bottom edge.for(var col:uint = 0;col<bitmapData.width;
col++){bitmapData.setPixel32(col,0,0xFF00FFFF);
bitmapData.setPixel32(col,1,0xFF00FFFF);bitmapData.setPixel32(col,bitmapData.height - 1,
0xFFFF00FF);bitmapData.setPixel32(col,bitmapData.height - 2,
0xFFFF00FF);} //End for loop} //end modify method//--------------------------------------------------////This method inverts all of the pixels in the top
// half of the incoming bitmap.private function invert(bitmap:Bitmap):void{
//Get the BitmapData object.var bitmapData:BitmapData = bitmap.bitmapData;
//Get a one-dimensional byte array of pixel data// from the top half of the bitmapData object
var rawBytes:ByteArray = new ByteArray();rawBytes = bitmapData.getPixels(new Rectangle(
0,0,bitmapData.width,bitmapData.height/2));//Invert the colors by subtracting each color// component value from 255.
var cnt:uint = 1;while(cnt<rawBytes.length){
rawBytes[cnt]= 255 - rawBytes[cnt];rawBytes[cnt + 1] = 255 - rawBytes[cnt + 1];
rawBytes[cnt + 2]= 255 - rawBytes[cnt + 2];cnt += 4;//increment the counter
}//end while loop//Put the modified pixels back in the bitmapData
// object.rawBytes.position = 0;//this is critical
bitmapData.setPixels(new Rectangle(0,0,bitmapData.width,bitmapData.height/2),
rawBytes);} //end invert method//--------------------------------------------------//} //end class
} //end package
This section contains a variety of miscellaneous materials.
-end-
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