actionscript 截图功能实现

由于截图访问的是 外部 rtmp直播流 所以调用BitmapData.draw时 控制台报以下错误：

　　SecurityError: Error #2123: 安全沙箱冲突:BitmapData.draw: XXX 不能访问 rtmp://XXXXX。未被授权访问任何策略文件。

解决方法是：

　　我们的视频服务器是用Crtmpserver，网上的解决办法大多是FMS的 ；

在转码服务器 的 BaseOutNetRTMPStream::SignalAttachedToInStream() 方法中添加以下 + 号的代码：

in void BaseOutNetRTMPStream::SignalAttachedToInStream(), I added the 
following code after stream begin to allow Video samples:

+        //XXX. notify |RtmpSampleAccess 
+    /* 
+        message = StreamMessageFactory::GetNotifyRtmpSampleAccess( 
+                        _pChannelVideo->id, _rtmpStreamId, absoluteTimestamp, false, true, 
true); 
+        TRACK_MESSAGE("Message:\n%s", STR(message.ToString())); 
+        if (!_pRTMPProtocol->SendMessage(message)) { 
+                FATAL("Unable to send message"); 
+                _pRTMPProtocol->EnqueueForDelete(); 
+                return false; 
+        } 
+  */ 
+ 
  

修改以下代码:
    //10. notify |RtmpSampleAccess 
    message = StreamMessageFactory::GetNotifyRtmpSampleAccess( 
        _pChannelAudio->id, _rtmpStreamId, 0, true, true, true); 
    TRACK_MESSAGE("Message:\n%s", STR(message.ToString())); 
    if (!_pRTMPProtocol->SendMessage(message)) { 
      FATAL("Unable to send message"); 
      _pRTMPProtocol->EnqueueForDelete(); 
      return; 
    } 

在actionscript中的 截图实现过程为：

var imager:BitmapData = new BitmapData(mvideo.width,mvideo.height);
                    ExternalInterface.call("errorFun","1");
                    imager.draw(mvideo.video);
                    var bs:ByteArray = new ByteArray();
                    imager.encode(new Rectangle(0,0,mvideo.width,mvideo.height), new flash.display.JPEGEncoderOptions(), bs);
                    var base64Code:String = Base64.encode(bs);
                    ExternalInterface.call("setImage",base64Code);

Base64的源码为：

/* Base64 library for ActionScript 3.0.
*
* Copyright (C) 2007 Ma Bingyao <andot@ujn.edu.cn>
* Version: 1.1
* LastModified: Oct 26, 2007
* This library is free.  You can redistribute it and/or modify it.
*/
/*
* interfaces:
* import org.phprpc.util.Base64;
* import flash.utils.ByteArray;
* var data:ByteArray = new ByteArray();
* data.writeUTFBytes("Hello PHPRPC");
* var b64:String = Base64.encode(data);
* trace(b64);
* trace(Base64.decode(b64));
*/
package com.zonekey.player{
        import flash.utils.ByteArray;
        public class Base64 {
                private static  const encodeChars:Array =
                    ['A','B','C','D','E','F','G','H',
                        'I','J','K','L','M','N','O','P',
                        'Q','R','S','T','U','V','W','X',
                        'Y','Z','a','b','c','d','e','f',
                        'g','h','i','j','k','l','m','n',
                        'o','p','q','r','s','t','u','v',
                        'w','x','y','z','0','1','2','3',
                        '4','5','6','7','8','9','+','/'];
                private static  const decodeChars:Array =
                    [-1, -1, -1, -1, -1, -1, -1, -1,
                        -1, -1, -1, -1, -1, -1, -1, -1,
                        -1, -1, -1, -1, -1, -1, -1, -1,
                        -1, -1, -1, -1, -1, -1, -1, -1,
                        -1, -1, -1, -1, -1, -1, -1, -1,
                        -1, -1, -1, 62, -1, -1, -1, 63,
                        52, 53, 54, 55, 56, 57, 58, 59,
                        60, 61, -1, -1, -1, -1, -1, -1,
                        -1,  0,  1,  2,  3,  4,  5,  6,
                         7,  8,  9, 10, 11, 12, 13, 14,
                        15, 16, 17, 18, 19, 20, 21, 22,
                        23, 24, 25, -1, -1, -1, -1, -1,
                        -1, 26, 27, 28, 29, 30, 31, 32,
                        33, 34, 35, 36, 37, 38, 39, 40,
                        41, 42, 43, 44, 45, 46, 47, 48,
                        49, 50, 51, -1, -1, -1, -1, -1];    

                public static function encode(data:ByteArray):String {
                        var out:Array = [];
                        var i:int = 0;
                        var j:int = 0;
                        var r:int = data.length % 3;
                        var len:int = data.length-r;
                        var c:int;
                        while (i < len) {
                                c = data[i++] << 16 | data[i++] << 8 | data[i++];
                                out[j++] = encodeChars[c >> 18] + encodeChars[c >> 12 & 0x3f] + encodeChars[c >> 6 & 0x3f] + encodeChars[c & 0x3f];
                            }
                        if (r == 1) {
                                c = data[i++];
                                out[j++] = encodeChars[c >> 2] + encodeChars[(c & 0x03) << 4] + "==";
                            }
                        else if (r == 2) {
                                c = data[i++] << 8 | data[i++];
                                out[j++] = encodeChars[c >> 10] + encodeChars[c >> 4 & 0x3f] + encodeChars[(c & 0x0f) << 2] + "=";
                            }
                        return out.join('');
                }

                public static function decode(str:String):ByteArray {
                    var c1:int;
                    var c2:int;
                    var c3:int;
                    var c4:int;
                    var i:int;
                    var len:int;
                    var out:ByteArray;
                    len = str.length;
                    i = 0;
                    out = new ByteArray();
                    while (i < len) {
                        do {
                            c1 = decodeChars[str.charCodeAt(i++) & 0xff];
                        } while (i < len && c1 == -1);
                        if (c1 == -1) {
                            break;
                        }
                        // c2
                        do {
                            c2 = decodeChars[str.charCodeAt(i++) & 0xff];
                        } while (i < len && c2 == -1);
                        if (c2 == -1) {
                            break;
                        }
                        out.writeByte((c1 << 2) | ((c2 & 0x30) >> 4));
                        // c3
                        do {
                            c3 = str.charCodeAt(i++) & 0xff;
                            if (c3 == 61) {
                                return out;
                            }
                            c3 = decodeChars[c3];
                        } while (i < len && c3 == -1);
                        if (c3 == -1) {
                            break;
                        }
                        out.writeByte(((c2 & 0x0f) << 4) | ((c3 & 0x3c) >> 2));
                        // c4
                        do {
                            c4 = str.charCodeAt(i++) & 0xff;
                            if (c4 == 61) {
                                return out;
                            }
                            c4 = decodeChars[c4];
                        } while (i < len && c4 == -1);
                        if (c4 == -1) {
                            break;
                        }
                        out.writeByte(((c3 & 0x03) << 6) | c4);
                    }
                    return out;
                }
            }
    }

至此，actionscript的截图并将图片的base64码传递给javascript的功能 就实现了。