as3 屏幕截图教程(附源码及代码说明)

////////////////////////////////// as源码 //////////////////////////////////
import JPGEncoder;
//设置要截屏的范围
var jpg:BitmapData=new BitmapData(stage.stageWidth,stage.stageHeight);//图片大小
jpg.draw(root);//截取整个舞台

var jpgCode:JPGEncoder=new JPGEncoder(85);//设置编码器(图片品质)
var jpgStream:ByteArray=jpgCode.encode(jpg);//对截取的图片进行编码

//和PHP交互
var url:URLRequestHeader=new URLRequestHeader("Content-type", "application/octet-stream");
var request:URLRequest = new URLRequest("download.php?name=jpg.jpg");
request.requestHeaders.push(url);
request.method = URLRequestMethod.POST;
request.data = jpgStream;
navigateToURL(request, "_blank");

////////////////////////////////// PHP源码 //////////////////////////////////
<?php

if (isset($GLOBALS["HTTP_RAW_POST_DATA"]))
{
// get bytearray
$jpg = $GLOBALS["HTTP_RAW_POST_DATA"];

// add headers for download dialog-box
header("=Content-Type: image/jpeg");
header("Content-Disposition: attachment; filename=".$_GET["name"]);
echo $jpg;
}

?>

////////////////////////////////// JPGEncoder源码 //////////////////////////////////
package {
import flash.geom.*;
import flash.display.*;
import flash.utils.*;

  
public class JPGEncoder
{

   // Static table initialization

   private var ZigZag:Array = [
    0, 1, 5, 6,14,15,27,28,
    2, 4, 7,13,16,26,29,42,
    3, 8,12,17,25,30,41,43,
    9,11,18,24,31,40,44,53,
    10,19,23,32,39,45,52,54,
    20,22,33,38,46,51,55,60,
    21,34,37,47,50,56,59,61,
    35,36,48,49,57,58,62,63
   ];

   private var YTable:Array = new Array(64);
   private var UVTable:Array = new Array(64);
   private var fdtbl_Y:Array = new Array(64);
   private var fdtbl_UV:Array = new Array(64);

   private function initQuantTables(sf:int):void
   {
    var i:int;
    var t:Number;
    var YQT:Array = [
     16, 11, 10, 16, 24, 40, 51, 61,
     12, 12, 14, 19, 26, 58, 60, 55,
     14, 13, 16, 24, 40, 57, 69, 56,
     14, 17, 22, 29, 51, 87, 80, 62,
     18, 22, 37, 56, 68,109,103, 77,
     24, 35, 55, 64, 81,104,113, 92,
     49, 64, 78, 87,103,121,120,101,
     72, 92, 95, 98,112,100,103, 99
    ];
    for (i = 0; i < 64; i++) {
     t = Math.floor((YQT[i]*sf+50)/100);
     if (t < 1) {
      t = 1;
     } else if (t > 255) {
      t = 255;
     }
     YTable[ZigZag[i]] = t;
    }
    var UVQT:Array = [
     17, 18, 24, 47, 99, 99, 99, 99,
     18, 21, 26, 66, 99, 99, 99, 99,
     24, 26, 56, 99, 99, 99, 99, 99,
     47, 66, 99, 99, 99, 99, 99, 99,
     99, 99, 99, 99, 99, 99, 99, 99,
     99, 99, 99, 99, 99, 99, 99, 99,
     99, 99, 99, 99, 99, 99, 99, 99,
     99, 99, 99, 99, 99, 99, 99, 99
    ];
    for (i = 0; i < 64; i++) {
     t = Math.floor((UVQT[i]*sf+50)/100);
     if (t < 1) {
      t = 1;
     } else if (t > 255) {
      t = 255;
     }
     UVTable[ZigZag[i]] = t;
    }
    var aasf:Array = [
     1.0, 1.387039845, 1.306562965, 1.175875602,
     1.0, 0.785694958, 0.541196100, 0.275899379
    ];
    i = 0;
    for (var row:int = 0; row < 8; row++)
    {
     for (var col:int = 0; col < 8; col++)
     {
      fdtbl_Y[i] = (1.0 / (YTable [ZigZag[i]] * aasf[row] * aasf[col] * 8.0));
      fdtbl_UV[i] = (1.0 / (UVTable[ZigZag[i]] * aasf[row] * aasf[col] * 8.0));
      i++;