AS3 -- 位图与二进制的转换

最新推荐文章于 2021-12-03 09:19:11 发布

转载最新推荐文章于 2021-12-03 09:19:11 发布 · 968 阅读

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/xlx12138/p/11019306.html

本文介绍了一个使用ActionScript 3 (AS3) 编写的类，该类能够将位图数据转换为有效的PNG格式。通过创建字节流并写入PNG签名，构建IHDR、IDAT和IEND块，实现位图到PNG的编码过程。

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import flash.utils.ByteArray;

/**
* Class that converts BitmapData into a valid PNG
*/
public class

{
/**
*
* 位图存为二进制 //二进制转化为位图
*/
public static function encode(img:BitmapData):ByteArray {
// Create output byte array
var png:ByteArray = new ByteArray();
// Write PNG signature
png.writeUnsignedInt(0x89504e47);
png.writeUnsignedInt(0x0D0A1A0A);
// Build IHDR chunk
var IHDR:ByteArray = new ByteArray();
IHDR.writeInt(img.width);
IHDR.writeInt(img.height);
IHDR.writeUnsignedInt(0x08060000); // 32bit RGBA
IHDR.writeByte(0);
writeChunk(png,0x49484452,IHDR);
// Build IDAT chunk
var IDAT:ByteArray= new ByteArray();
for(var i:int=0;i < img.height;i++) {
// no filter
IDAT.writeByte(0);
var p:uint;
var j:int;
if ( !img.transparent ) {
for(j=0;j < img.width;j++) {
p = img.getPixel(j,i);
IDAT.writeUnsignedInt(
uint(((p&0xFFFFFF) << 8)|0xFF));
}
} else {
for(j=0;j < img.width;j++) {
p = img.getPixel32(j,i);
IDAT.writeUnsignedInt(
uint(((p&0xFFFFFF) << 8)|
(p>>>24)));
}
}
}
IDAT.compress();
writeChunk(png,0x49444154,IDAT);
// Build IEND chunk
writeChunk(png,0x49454E44,null);
// return PNG
return png;
}

private static var crcTable:Array;
private static var crcTableComputed:Boolean = false;

private static function writeChunk(png:ByteArray,
type:uint, data:ByteArray):void {
if (!crcTableComputed) {
crcTableComputed = true;
crcTable = [];
var c:uint;
for (var n:uint = 0; n < 256; n++) {
c = n;
for (var k:uint = 0; k < 8; k++) {
if (c & 1) {
c = uint(uint(0xedb88320) ^
uint(c >>> 1));
} else {
c = uint(c >>> 1);
}
}
crcTable[n] = c;
}
}
var len:uint = 0;
if (data != null) {
len = data.length;
}
png.writeUnsignedInt(len);
var p:uint = png.position;
png.writeUnsignedInt(type);
if ( data != null ) {
png.writeBytes(data);
}
var e:uint = png.position;
png.position = p;
c = 0xffffffff;
for (var i:int = 0; i < (e-p); i++) {
c = uint(crcTable[
(c ^ png.readUnsignedByte()) &
uint(0xff)] ^ uint(c >>> 8));
}
c = uint(c^uint(0xffffffff));
png.position = e;
png.writeUnsignedInt(c);
}
}
}

//二进制转化为位图

package
{
import flash.display.Bitmap;
import flash.display.Loader;
import flash.display.Sprite;
import flash.events.Event;
import flash.net.URLRequest;
import flash.utils.ByteArray;

public class test extends Sprite
{
// var reg:RegExp = new RegExp("[0-9]","g");
// var str:String = "-1.1.1.1000"
private var _loadeImg:Loader;
private var _loader:Loader;
public function test()
{
// trace(str.match(reg).length)
_loadeImg = new Loader();
_loadeImg.contentLoaderInfo.addEventListener(Event.COMPLETE,onImgComplete);
_loadeImg.load(new URLRequest("1.png"));
}

protected function onImgComplete(event:Event):void
{
var bmp:Bitmap = _loadeImg.content as Bitmap;

var bytes:ByteArray = PNGEncoder.encode(bmp.bitmapData);

_loader = new Loader();
_loader.loadBytes(bytes);
_loader.contentLoaderInfo.addEventListener(Event.COMPLETE, complete);

}

protected function complete(event:Event):void
{
var bmp:Bitmap = _loadeImg.content as Bitmap;
addChild(bmp);

}
}
}

转载于:https://www.cnblogs.com/xlx12138/p/11019306.html