实例介绍
【实例简介】
【实例截图】
【核心代码】
/* Copyright (c) 2008, Adobe Systems Incorporated All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of Adobe Systems Incorporated nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package com.adobe.images { import flash.geom.*; import flash.display.*; import flash.utils.*; /** * Class that converts BitmapData into a valid JPEG */ 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 ; } } } private var YDC_HT:Array; private var UVDC_HT:Array; private var YAC_HT:Array; private var UVAC_HT:Array; private function computeHuffmanTbl(nrcodes:Array, std_table:Array):Array { var codevalue:int = 0; var pos_in_table:int = 0; var HT:Array = new Array(); for (var k:int=1; k<=16; k ) { for (var j:int=1; j<=nrcodes[k]; j ) { HT[std_table[pos_in_table]] = new BitString(); HT[std_table[pos_in_table]].val = codevalue; HT[std_table[pos_in_table]].len = k; pos_in_table ; codevalue ; } codevalue*=2; } return HT; } private var std_dc_luminance_nrcodes:Array = [0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0]; private var std_dc_luminance_values:Array = [0,1,2,3,4,5,6,7,8,9,10,11]; private var std_ac_luminance_nrcodes:Array = [0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d]; private var std_ac_luminance_values:Array = [ 0x01,0x02,0x03,0x00,0x04,0x11,0x05,0x12, 0x21,0x31,0x41,0x06,0x13,0x51,0x61,0x07, 0x22,0x71,0x14,0x32,0x81,0x91,0xa1,0x08, 0x23,0x42,0xb1,0xc1,0x15,0x52,0xd1,0xf0, 0x24,0x33,0x62,0x72,0x82,0x09,0x0a,0x16, 0x17,0x18,0x19,0x1a,0x25,0x26,0x27,0x28, 0x29,0x2a,0x34,0x35,0x36,0x37,0x38,0x39, 0x3a,0x43,0x44,0x45,0x46,0x47,0x48,0x49, 0x4a,0x53,0x54,0x55,0x56,0x57,0x58,0x59, 0x5a,0x63,0x64,0x65,0x66,0x67,0x68,0x69, 0x6a,0x73,0x74,0x75,0x76,0x77,0x78,0x79, 0x7a,0x83,0x84,0x85,0x86,0x87,0x88,0x89, 0x8a,0x92,0x93,0x94,0x95,0x96,0x97,0x98, 0x99,0x9a,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7, 0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,0xb5,0xb6, 0xb7,0xb8,0xb9,0xba,0xc2,0xc3,0xc4,0xc5, 0xc6,0xc7,0xc8,0xc9,0xca,0xd2,0xd3,0xd4, 0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xe1,0xe2, 0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea, 0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8, 0xf9,0xfa ]; private var std_dc_chrominance_nrcodes:Array = [0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0]; private var std_dc_chrominance_values:Array = [0,1,2,3,4,5,6,7,8,9,10,11]; private var std_ac_chrominance_nrcodes:Array = [0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77]; private var std_ac_chrominance_values:Array = [ 0x00,0x01,0x02,0x03,0x11,0x04,0x05,0x21, 0x31,0x06,0x12,0x41,0x51,0x07,0x61,0x71, 0x13,0x22,0x32,0x81,0x08,0x14,0x42,0x91, 0xa1,0xb1,0xc1,0x09,0x23,0x33,0x52,0xf0, 0x15,0x62,0x72,0xd1,0x0a,0x16,0x24,0x34, 0xe1,0x25,0xf1,0x17,0x18,0x19,0x1a,0x26, 0x27,0x28,0x29,0x2a,0x35,0x36,0x37,0x38, 0x39,0x3a,0x43,0x44,0x45,0x46,0x47,0x48, 0x49,0x4a,0x53,0x54,0x55,0x56,0x57,0x58, 0x59,0x5a,0x63,0x64,0x65,0x66,0x67,0x68, 0x69,0x6a,0x73,0x74,0x75,0x76,0x77,0x78, 0x79,0x7a,0x82,0x83,0x84,0x85,0x86,0x87, 0x88,0x89,0x8a,0x92,0x93,0x94,0x95,0x96, 0x97,0x98,0x99,0x9a,0xa2,0xa3,0xa4,0xa5, 0xa6,0xa7,0xa8,0xa9,0xaa,0xb2,0xb3,0xb4, 0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xc2,0xc3, 0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xd2, 0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda, 0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9, 0xea,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8, 0xf9,0xfa ]; private function initHuffmanTbl():void { YDC_HT = computeHuffmanTbl(std_dc_luminance_nrcodes,std_dc_luminance_values); UVDC_HT = computeHuffmanTbl(std_dc_chrominance_nrcodes,std_dc_chrominance_values); YAC_HT = computeHuffmanTbl(std_ac_luminance_nrcodes,std_ac_luminance_values); UVAC_HT = computeHuffmanTbl(std_ac_chrominance_nrcodes,std_ac_chrominance_values); } private var bitcode:Array = new Array(65535); private var category:Array = new Array(65535); private function initCategoryNumber():void { var nrlower:int = 1; var nrupper:int = 2; var nr:int; for (var cat:int=1; cat<=15; cat ) { //Positive numbers for (nr=nrlower; nr<nrupper; nr ) { category[32767 nr] = cat; bitcode[32767 nr] = new BitString(); bitcode[32767 nr].len = cat; bitcode[32767 nr].val = nr; } //Negative numbers for (nr=-(nrupper-1); nr<=-nrlower; nr ) { category[32767 nr] = cat; bitcode[32767 nr] = new BitString(); bitcode[32767 nr].len = cat; bitcode[32767 nr].val = nrupper-1 nr; } nrlower <<= 1; nrupper <<= 1; } } // IO functions private var byteout:ByteArray; private var bytenew:int = 0; private var bytepos:int = 7; private function writeBits(bs:BitString):void { var value:int = bs.val; var posval:int = bs.len-1; while ( posval >= 0 ) { if (value & uint(1 << posval) ) { bytenew |= uint(1 << bytepos); } posval--; bytepos--; if (bytepos < 0) { if (bytenew == 0xFF) { writeByte(0xFF); writeByte(0); } else { writeByte(bytenew); } bytepos=7; bytenew=0; } } } private function writeByte(value:int):void { byteout.writeByte(value); } private function writeWord(value:int):void { writeByte((value>>8)&0xFF); writeByte((value )&0xFF); } // DCT & quantization core private function fDCTQuant(data:Array, fdtbl:Array):Array { var tmp0:Number, tmp1:Number, tmp2:Number, tmp3:Number, tmp4:Number, tmp5:Number, tmp6:Number, tmp7:Number; var tmp10:Number, tmp11:Number, tmp12:Number, tmp13:Number; var z1:Number, z2:Number, z3:Number, z4:Number, z5:Number, z11:Number, z13:Number; var i:int; /* Pass 1: process rows. */ var dataOff:int=0; for (i=0; i<8; i ) { tmp0 = data[dataOff 0] data[dataOff 7]; tmp7 = data[dataOff 0] - data[dataOff 7]; tmp1 = data[dataOff 1] data[dataOff 6]; tmp6 = data[dataOff 1] - data[dataOff 6]; tmp2 = data[dataOff 2] data[dataOff 5]; tmp5 = data[dataOff 2] - data[dataOff 5]; tmp3 = data[dataOff 3] data[dataOff 4]; tmp4 = data[dataOff 3] - data[dataOff 4]; /* Even part */ tmp10 = tmp0 tmp3; /* phase 2 */ tmp13 = tmp0 - tmp3; tmp11 = tmp1 tmp2; tmp12 = tmp1 - tmp2; data[dataOff 0] = tmp10 tmp11; /* phase 3 */ data[dataOff 4] = tmp10 - tmp11; z1 = (tmp12 tmp13) * 0.707106781; /* c4 */ data[dataOff 2] = tmp13 z1; /* phase 5 */ data[dataOff 6] = tmp13 - z1; /* Odd part */ tmp10 = tmp4 tmp5; /* phase 2 */ tmp11 = tmp5 tmp6; tmp12 = tmp6 tmp7; /* The rotator is modified from fig 4-8 to avoid extra negations. */ z5 = (tmp10 - tmp12) * 0.382683433; /* c6 */ z2 = 0.541196100 * tmp10 z5; /* c2-c6 */ z4 = 1.306562965 * tmp12 z5; /* c2 c6 */ z3 = tmp11 * 0.707106781; /* c4 */ z11 = tmp7 z3; /* phase 5 */ z13 = tmp7 - z3; data[dataOff 5] = z13 z2; /* phase 6 */ data[dataOff 3] = z13 - z2; data[dataOff 1] = z11 z4; data[dataOff 7] = z11 - z4; dataOff = 8; /* advance pointer to next row */ } /* Pass 2: process columns. */ dataOff = 0; for (i=0; i<8; i ) { tmp0 = data[dataOff 0] data[dataOff 56]; tmp7 = data[dataOff 0] - data[dataOff 56]; tmp1 = data[dataOff 8] data[dataOff 48]; tmp6 = data[dataOff 8] - data[dataOff 48]; tmp2 = data[dataOff 16] data[dataOff 40]; tmp5 = data[dataOff 16] - data[dataOff 40]; tmp3 = data[dataOff 24] data[dataOff 32]; tmp4 = data[dataOff 24] - data[dataOff 32]; /* Even part */ tmp10 = tmp0 tmp3; /* phase 2 */ tmp13 = tmp0 - tmp3; tmp11 = tmp1 tmp2; tmp12 = tmp1 - tmp2; data[dataOff 0] = tmp10 tmp11; /* phase 3 */ data[dataOff 32] = tmp10 - tmp11; z1 = (tmp12 tmp13) * 0.707106781; /* c4 */ data[dataOff 16] = tmp13 z1; /* phase 5 */ data[dataOff 48] = tmp13 - z1; /* Odd part */ tmp10 = tmp4 tmp5; /* phase 2 */ tmp11 = tmp5 tmp6; tmp12 = tmp6 tmp7; /* The rotator is modified from fig 4-8 to avoid extra negations. */ z5 = (tmp10 - tmp12) * 0.382683433; /* c6 */ z2 = 0.541196100 * tmp10 z5; /* c2-c6 */ z4 = 1.306562965 * tmp12 z5; /* c2 c6 */ z3 = tmp11 * 0.707106781; /* c4 */ z11 = tmp7 z3; /* phase 5 */ z13 = tmp7 - z3; data[dataOff 40] = z13 z2; /* phase 6 */ data[dataOff 24] = z13 - z2; data[dataOff 8] = z11 z4; data[dataOff 56] = z11 - z4; dataOff ; /* advance pointer to next column */ } // Quantize/descale the coefficients for (i=0; i<64; i ) { // Apply the quantization and scaling factor & Round to nearest integer data[i] = Math.round((data[i]*fdtbl[i])); } return data; } // Chunk writing private function writeAPP0():void { writeWord(0xFFE0); // marker writeWord(16); // length writeByte(0x4A); // J writeByte(0x46); // F writeByte(0x49); // I writeByte(0x46); // F writeByte(0); // = "JFIF",'\0' writeByte(1); // versionhi writeByte(1); // versionlo writeByte(0); // xyunits writeWord(1); // xdensity writeWord(1); // ydensity writeByte(0); // thumbnwidth writeByte(0); // thumbnheight } private function writeSOF0(width:int, height:int):void { writeWord(0xFFC0); // marker writeWord(17); // length, truecolor YUV JPG writeByte(8); // precision writeWord(height); writeWord(width); writeByte(3); // nrofcomponents writeByte(1); // IdY writeByte(0x11); // HVY writeByte(0); // QTY writeByte(2); // IdU writeByte(0x11); // HVU writeByte(1); // QTU writeByte(3); // IdV writeByte(0x11); // HVV writeByte(1); // QTV } private function writeDQT():void { writeWord(0xFFDB); // marker writeWord(132); // length writeByte(0); var i:int; for (i=0; i<64; i ) { writeByte(YTable[i]); } writeByte(1); for (i=0; i<64; i ) { writeByte(UVTable[i]); } } private function writeDHT():void { writeWord(0xFFC4); // marker writeWord(0x01A2); // length var i:int; writeByte(0); // HTYDCinfo for (i=0; i<16; i ) { writeByte(std_dc_luminance_nrcodes[i 1]); } for (i=0; i<=11; i ) { writeByte(std_dc_luminance_values[i]); } writeByte(0x10); // HTYACinfo for (i=0; i<16; i ) { writeByte(std_ac_luminance_nrcodes[i 1]); } for (i=0; i<=161; i ) { writeByte(std_ac_luminance_values[i]); } writeByte(1); // HTUDCinfo for (i=0; i<16; i ) { writeByte(std_dc_chrominance_nrcodes[i 1]); } for (i=0; i<=11; i ) { writeByte(std_dc_chrominance_values[i]); } writeByte(0x11); // HTUACinfo for (i=0; i<16; i ) { writeByte(std_ac_chrominance_nrcodes[i 1]); } for (i=0; i<=161; i ) { writeByte(std_ac_chrominance_values[i]); } } private function writeSOS():void { writeWord(0xFFDA); // marker writeWord(12); // length writeByte(3); // nrofcomponents writeByte(1); // IdY writeByte(0); // HTY writeByte(2); // IdU writeByte(0x11); // HTU writeByte(3); // IdV writeByte(0x11); // HTV writeByte(0); // Ss writeByte(0x3f); // Se writeByte(0); // Bf } // Core processing private var DU:Array = new Array(64); private function processDU(CDU:Array, fdtbl:Array, DC:Number, HTDC:Array, HTAC:Array):Number { var EOB:BitString = HTAC[0x00]; var M16zeroes:BitString = HTAC[0xF0]; var i:int; var DU_DCT:Array = fDCTQuant(CDU, fdtbl); //ZigZag reorder for (i=0;i<64;i ) { DU[ZigZag[i]]=DU_DCT[i]; } var Diff:int = DU[0] - DC; DC = DU[0]; //Encode DC if (Diff==0) { writeBits(HTDC[0]); // Diff might be 0 } else { writeBits(HTDC[category[32767 Diff]]); writeBits(bitcode[32767 Diff]); } //Encode ACs var end0pos:int = 63; for (; (end0pos>0)&&(DU[end0pos]==0); end0pos--) { }; //end0pos = first element in reverse order !=0 if ( end0pos == 0) { writeBits(EOB); return DC; } i = 1; while ( i <= end0pos ) { var startpos:int = i; for (; (DU[i]==0) && (i<=end0pos); i ) { } var nrzeroes:int = i-startpos; if ( nrzeroes >= 16 ) { for (var nrmarker:int=1; nrmarker <= nrzeroes/16; nrmarker ) { writeBits(M16zeroes); } nrzeroes = int(nrzeroes&0xF); } writeBits(HTAC[nrzeroes*16 category[32767 DU[i]]]); writeBits(bitcode[32767 DU[i]]); i ; } if ( end0pos != 63 ) { writeBits(EOB); } return DC; } private var YDU:Array = new Array(64); private var UDU:Array = new Array(64); private var VDU:Array = new Array(64); private function RGB2YUV(img:BitmapData, xpos:int, ypos:int):void { var pos:int=0; for (var y:int=0; y<8; y ) { for (var x:int=0; x<8; x ) { var P:uint = img.getPixel32(xpos x,ypos y); var R:Number = Number((P>>16)&0xFF); var G:Number = Number((P>> 8)&0xFF); var B:Number = Number((P )&0xFF); YDU[pos]=((( 0.29900)*R ( 0.58700)*G ( 0.11400)*B))-128; UDU[pos]=(((-0.16874)*R (-0.33126)*G ( 0.50000)*B)); VDU[pos]=((( 0.50000)*R (-0.41869)*G (-0.08131)*B)); pos ; } } } /** * Constructor for JPEGEncoder class * * @param quality The quality level between 1 and 100 that detrmines the * level of compression used in the generated JPEG * @langversion ActionScript 3.0 * @playerversion Flash 9.0 * @tiptext */ public function JPGEncoder(quality:Number = 50) { if (quality <= 0) { quality = 1; } if (quality > 100) { quality = 100; } var sf:int = 0; if (quality < 50) { sf = int(5000 / quality); } else { sf = int(200 - quality*2); } // Create tables initHuffmanTbl(); initCategoryNumber(); initQuantTables(sf); } /** * Created a JPEG image from the specified BitmapData * * @param image The BitmapData that will be converted into the JPEG format. * @return a ByteArray representing the JPEG encoded image data. * @langversion ActionScript 3.0 * @playerversion Flash 9.0 * @tiptext */ public function encode(image:BitmapData):ByteArray { // Initialize bit writer byteout = new ByteArray(); bytenew=0; bytepos=7; // Add JPEG headers writeWord(0xFFD8); // SOI writeAPP0(); writeDQT(); writeSOF0(image.width,image.height); writeDHT(); writeSOS(); // Encode 8x8 macroblocks var DCY:Number=0; var DCU:Number=0; var DCV:Number=0; bytenew=0; bytepos=7; for (var ypos:int=0; ypos<image.height; ypos =8) { for (var xpos:int=0; xpos<image.width; xpos =8) { RGB2YUV(image, xpos, ypos); DCY = processDU(YDU, fdtbl_Y, DCY, YDC_HT, YAC_HT); DCU = processDU(UDU, fdtbl_UV, DCU, UVDC_HT, UVAC_HT); DCV = processDU(VDU, fdtbl_UV, DCV, UVDC_HT, UVAC_HT); } } // Do the bit alignment of the EOI marker if ( bytepos >= 0 ) { var fillbits:BitString = new BitString(); fillbits.len = bytepos 1; fillbits.val = (1<<(bytepos 1))-1; writeBits(fillbits); } writeWord(0xFFD9); //EOI return byteout; } } }
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