378 lines
10 KiB
ActionScript
378 lines
10 KiB
ActionScript
////////////////////////////////////////////////////////////////////////////////
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//
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// ADOBE SYSTEMS INCORPORATED
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// Copyright 2004-2007 Adobe Systems Incorporated
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// All Rights Reserved.
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//
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// NOTICE: Adobe permits you to use, modify, and distribute this file
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// in accordance with the terms of the license agreement accompanying it.
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//
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////////////////////////////////////////////////////////////////////////////////
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package mx.utils
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{
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import flash.utils.ByteArray;
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/**
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* A utility class to encode a String or ByteArray as a Base64 encoded String.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public class Base64Encoder
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{
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//--------------------------------------------------------------------------
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//
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// Static Class Variables
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//
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//--------------------------------------------------------------------------
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/**
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* Constant definition for the string "UTF-8".
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public static const CHARSET_UTF_8:String = "UTF-8";
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/**
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* The character codepoint to be inserted into the encoded output to
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* denote a new line if <code>insertNewLines</code> is true.
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*
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* The default is <code>10</code> to represent the line feed <code>\n</code>.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public static var newLine:int = 10;
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//--------------------------------------------------------------------------
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//
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// Constructor
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//
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//--------------------------------------------------------------------------
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/**
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* Constructor.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public function Base64Encoder()
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{
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super();
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reset();
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}
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//--------------------------------------------------------------------------
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//
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// Variables
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//
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//--------------------------------------------------------------------------
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/**
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* A Boolean flag to control whether the sequence of characters specified
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* for <code>Base64Encoder.newLine</code> are inserted every 76 characters
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* to wrap the encoded output.
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*
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* The default is true.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public var insertNewLines:Boolean = true;
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//--------------------------------------------------------------------------
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//
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// Public Methods
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//
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//--------------------------------------------------------------------------
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/**
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* @private
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*/
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public function drain():String
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{
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var result:String = "";
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for (var i:uint = 0; i < _buffers.length; i++)
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{
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var buffer:Array = _buffers[i] as Array;
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result += String.fromCharCode.apply(null, buffer);
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}
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_buffers = [];
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_buffers.push([]);
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return result;
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}
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/**
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* Encodes the characters of a String in Base64 and adds the result to
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* an internal buffer. Subsequent calls to this method add on to the
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* internal buffer. After all data have been encoded, call
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* <code>toString()</code> to obtain a Base64 encoded String.
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*
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* @param data The String to encode.
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* @param offset The character position from which to start encoding.
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* @param length The number of characters to encode from the offset.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public function encode(data:String, offset:uint=0, length:uint=0):void
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{
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if (length == 0)
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length = data.length;
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var currentIndex:uint = offset;
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var endIndex:uint = offset + length;
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if (endIndex > data.length)
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endIndex = data.length;
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while (currentIndex < endIndex)
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{
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_work[_count] = data.charCodeAt(currentIndex);
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_count++;
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if (_count == _work.length || endIndex - currentIndex == 1)
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{
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encodeBlock();
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_count = 0;
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_work[0] = 0;
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_work[1] = 0;
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_work[2] = 0;
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}
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currentIndex++;
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}
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}
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/**
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* Encodes the UTF-8 bytes of a String in Base64 and adds the result to an
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* internal buffer. The UTF-8 information does not contain a length prefix.
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* Subsequent calls to this method add on to the internal buffer. After all
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* data have been encoded, call <code>toString()</code> to obtain a Base64
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* encoded String.
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*
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* @param data The String to encode.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public function encodeUTFBytes(data:String):void
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{
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var bytes:ByteArray = new ByteArray();
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bytes.writeUTFBytes(data);
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bytes.position = 0;
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encodeBytes(bytes);
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}
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/**
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* Encodes a ByteArray in Base64 and adds the result to an internal buffer.
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* Subsequent calls to this method add on to the internal buffer. After all
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* data have been encoded, call <code>toString()</code> to obtain a
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* Base64 encoded String.
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*
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* @param data The ByteArray to encode.
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* @param offset The index from which to start encoding.
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* @param length The number of bytes to encode from the offset.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public function encodeBytes(data:ByteArray, offset:uint=0, length:uint=0):void
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{
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if (length == 0)
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length = data.length;
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var oldPosition:uint = data.position;
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data.position = offset;
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var currentIndex:uint = offset;
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var endIndex:uint = offset + length;
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if (endIndex > data.length)
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endIndex = data.length;
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while (currentIndex < endIndex)
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{
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_work[_count] = data[currentIndex];
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_count++;
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if (_count == _work.length || endIndex - currentIndex == 1)
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{
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encodeBlock();
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_count = 0;
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_work[0] = 0;
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_work[1] = 0;
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_work[2] = 0;
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}
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currentIndex++;
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}
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data.position = oldPosition;
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}
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/**
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* @private
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*/
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public function flush():String
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{
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if (_count > 0)
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encodeBlock();
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var result:String = drain();
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reset();
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return result;
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}
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/**
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* Clears all buffers and resets the encoder to its initial state.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public function reset():void
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{
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_buffers = [];
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_buffers.push([]);
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_count = 0;
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_line = 0;
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_work[0] = 0;
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_work[1] = 0;
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_work[2] = 0;
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}
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/**
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* Returns the current buffer as a Base64 encoded String. Note that
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* calling this method also clears the buffer and resets the
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* encoder to its initial state.
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*
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* @return The Base64 encoded String.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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public function toString():String
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{
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return flush();
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}
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//--------------------------------------------------------------------------
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//
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// Private Methods
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//
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//--------------------------------------------------------------------------
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/**
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* @private
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*/
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private function encodeBlock():void
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{
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var currentBuffer:Array = _buffers[_buffers.length - 1] as Array;
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if (currentBuffer.length >= MAX_BUFFER_SIZE)
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{
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currentBuffer = [];
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_buffers.push(currentBuffer);
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}
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currentBuffer.push(ALPHABET_CHAR_CODES[(_work[0] & 0xFF) >> 2]);
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currentBuffer.push(ALPHABET_CHAR_CODES[((_work[0] & 0x03) << 4) | ((_work[1] & 0xF0) >> 4)]);
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if (_count > 1)
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currentBuffer.push(ALPHABET_CHAR_CODES[((_work[1] & 0x0F) << 2) | ((_work[2] & 0xC0) >> 6) ]);
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else
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currentBuffer.push(ESCAPE_CHAR_CODE);
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if (_count > 2)
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currentBuffer.push(ALPHABET_CHAR_CODES[_work[2] & 0x3F]);
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else
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currentBuffer.push(ESCAPE_CHAR_CODE);
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if (insertNewLines)
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{
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if ((_line += 4) == 76)
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{
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currentBuffer.push(newLine);
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_line = 0;
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}
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}
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}
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//--------------------------------------------------------------------------
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//
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// Private Variables
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//
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//--------------------------------------------------------------------------
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/**
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* An Array of buffer Arrays.
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*
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* @langversion 3.0
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* @playerversion Flash 9
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* @playerversion AIR 1.1
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* @productversion Flex 3
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*/
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private var _buffers:Array;
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private var _count:uint;
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private var _line:uint;
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private var _work:Array = [ 0, 0, 0 ];
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/**
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* This value represents a safe number of characters (i.e. arguments) that
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* can be passed to String.fromCharCode.apply() without exceeding the AVM+
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* stack limit.
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*
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* @private
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*/
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public static const MAX_BUFFER_SIZE:uint = 32767;
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private static const ESCAPE_CHAR_CODE:Number = 61; // The '=' char
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/*
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '+', '/'
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*/
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private static const ALPHABET_CHAR_CODES:Array =
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[
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65, 66, 67, 68, 69, 70, 71, 72,
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73, 74, 75, 76, 77, 78, 79, 80,
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81, 82, 83, 84, 85, 86, 87, 88,
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89, 90, 97, 98, 99, 100, 101, 102,
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103, 104, 105, 106, 107, 108, 109, 110,
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111, 112, 113, 114, 115, 116, 117, 118,
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119, 120, 121, 122, 48, 49, 50, 51,
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52, 53, 54, 55, 56, 57, 43, 47
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];
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}
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}
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