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twister-html/js/jpeg_encoder_basic.js

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/*
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.
*/
/*
JPEG encoder ported to JavaScript and optimized by Andreas Ritter, www.bytestrom.eu, 11/2009
Basic GUI blocking jpeg encoder
*/
function JPEGEncoder(quality) {
var self = this;
var fround = Math.round;
var ffloor = Math.floor;
var YTable = new Array(64);
var UVTable = new Array(64);
var fdtbl_Y = new Array(64);
var fdtbl_UV = new Array(64);
var YDC_HT;
var UVDC_HT;
var YAC_HT;
var UVAC_HT;
var bitcode = new Array(65535);
var category = new Array(65535);
var outputfDCTQuant = new Array(64);
var DU = new Array(64);
var byteout = [];
var bytenew = 0;
var bytepos = 7;
var YDU = new Array(64);
var UDU = new Array(64);
var VDU = new Array(64);
var clt = new Array(256);
var RGB_YUV_TABLE = new Array(2048);
var currentQuality;
var ZigZag = [
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
];
var std_dc_luminance_nrcodes = [0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0];
var std_dc_luminance_values = [0,1,2,3,4,5,6,7,8,9,10,11];
var std_ac_luminance_nrcodes = [0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d];
var std_ac_luminance_values = [
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
];
var std_dc_chrominance_nrcodes = [0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0];
var std_dc_chrominance_values = [0,1,2,3,4,5,6,7,8,9,10,11];
var std_ac_chrominance_nrcodes = [0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77];
var std_ac_chrominance_values = [
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
];
function initQuantTables(sf){
var YQT = [
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 (var i = 0; i < 64; i++) {
var t = ffloor((YQT[i]*sf+50)/100);
if (t < 1) {
t = 1;
} else if (t > 255) {
t = 255;
}
YTable[ZigZag[i]] = t;
}
var UVQT = [
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 (var j = 0; j < 64; j++) {
var u = ffloor((UVQT[j]*sf+50)/100);
if (u < 1) {
u = 1;
} else if (u > 255) {
u = 255;
}
UVTable[ZigZag[j]] = u;
}
var aasf = [
1.0, 1.387039845, 1.306562965, 1.175875602,
1.0, 0.785694958, 0.541196100, 0.275899379
];
var k = 0;
for (var row = 0; row < 8; row++)
{
for (var col = 0; col < 8; col++)
{
fdtbl_Y[k] = (1.0 / (YTable [ZigZag[k]] * aasf[row] * aasf[col] * 8.0));
fdtbl_UV[k] = (1.0 / (UVTable[ZigZag[k]] * aasf[row] * aasf[col] * 8.0));
k++;
}
}
}
function computeHuffmanTbl(nrcodes, std_table){
var codevalue = 0;
var pos_in_table = 0;
var HT = new Array();
for (var k = 1; k <= 16; k++) {
for (var j = 1; j <= nrcodes[k]; j++) {
HT[std_table[pos_in_table]] = [];
HT[std_table[pos_in_table]][0] = codevalue;
HT[std_table[pos_in_table]][1] = k;
pos_in_table++;
codevalue++;
}
codevalue*=2;
}
return HT;
}
function initHuffmanTbl()
{
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);
}
function initCategoryNumber()
{
var nrlower = 1;
var nrupper = 2;
for (var cat = 1; cat <= 15; cat++) {
//Positive numbers
for (var nr = nrlower; nr<nrupper; nr++) {
category[32767+nr] = cat;
bitcode[32767+nr] = [];
bitcode[32767+nr][1] = cat;
bitcode[32767+nr][0] = nr;
}
//Negative numbers
for (var nrneg =-(nrupper-1); nrneg<=-nrlower; nrneg++) {
category[32767+nrneg] = cat;
bitcode[32767+nrneg] = [];
bitcode[32767+nrneg][1] = cat;
bitcode[32767+nrneg][0] = nrupper-1+nrneg;
}
nrlower <<= 1;
nrupper <<= 1;
}
}
function initRGBYUVTable() {
for(var i = 0; i < 256;i++) {
RGB_YUV_TABLE[i] = 19595 * i;
RGB_YUV_TABLE[(i+ 256)>>0] = 38470 * i;
RGB_YUV_TABLE[(i+ 512)>>0] = 7471 * i + 0x8000;
RGB_YUV_TABLE[(i+ 768)>>0] = -11059 * i;
RGB_YUV_TABLE[(i+1024)>>0] = -21709 * i;
RGB_YUV_TABLE[(i+1280)>>0] = 32768 * i + 0x807FFF;
RGB_YUV_TABLE[(i+1536)>>0] = -27439 * i;
RGB_YUV_TABLE[(i+1792)>>0] = - 5329 * i;
}
}
// IO functions
function writeBits(bs)
{
var value = bs[0];
var posval = bs[1]-1;
while ( posval >= 0 ) {
if (value & (1 << posval) ) {
bytenew |= (1 << bytepos);
}
posval--;
bytepos--;
if (bytepos < 0) {
if (bytenew == 0xFF) {
writeByte(0xFF);
writeByte(0);
}
else {
writeByte(bytenew);
}
bytepos=7;
bytenew=0;
}
}
}
function writeByte(value)
{
byteout.push(clt[value]); // write char directly instead of converting later
}
function writeWord(value)
{
writeByte((value>>8)&0xFF);
writeByte((value )&0xFF);
}
// DCT & quantization core
function fDCTQuant(data, fdtbl)
{
var d0, d1, d2, d3, d4, d5, d6, d7;
/* Pass 1: process rows. */
var dataOff=0;
var i;
const I8 = 8;
const I64 = 64;
for (i=0; i<I8; ++i)
{
d0 = data[dataOff];
d1 = data[dataOff+1];
d2 = data[dataOff+2];
d3 = data[dataOff+3];
d4 = data[dataOff+4];
d5 = data[dataOff+5];
d6 = data[dataOff+6];
d7 = data[dataOff+7];
var tmp0 = d0 + d7;
var tmp7 = d0 - d7;
var tmp1 = d1 + d6;
var tmp6 = d1 - d6;
var tmp2 = d2 + d5;
var tmp5 = d2 - d5;
var tmp3 = d3 + d4;
var tmp4 = d3 - d4;
/* Even part */
var tmp10 = tmp0 + tmp3; /* phase 2 */
var tmp13 = tmp0 - tmp3;
var tmp11 = tmp1 + tmp2;
var tmp12 = tmp1 - tmp2;
data[dataOff] = tmp10 + tmp11; /* phase 3 */
data[dataOff+4] = tmp10 - tmp11;
var 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. */
var z5 = (tmp10 - tmp12) * 0.382683433; /* c6 */
var z2 = 0.541196100 * tmp10 + z5; /* c2-c6 */
var z4 = 1.306562965 * tmp12 + z5; /* c2+c6 */
var z3 = tmp11 * 0.707106781; /* c4 */
var z11 = tmp7 + z3; /* phase 5 */
var 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<I8; ++i)
{
d0 = data[dataOff];
d1 = data[dataOff + 8];
d2 = data[dataOff + 16];
d3 = data[dataOff + 24];
d4 = data[dataOff + 32];
d5 = data[dataOff + 40];
d6 = data[dataOff + 48];
d7 = data[dataOff + 56];
var tmp0p2 = d0 + d7;
var tmp7p2 = d0 - d7;
var tmp1p2 = d1 + d6;
var tmp6p2 = d1 - d6;
var tmp2p2 = d2 + d5;
var tmp5p2 = d2 - d5;
var tmp3p2 = d3 + d4;
var tmp4p2 = d3 - d4;
/* Even part */
var tmp10p2 = tmp0p2 + tmp3p2; /* phase 2 */
var tmp13p2 = tmp0p2 - tmp3p2;
var tmp11p2 = tmp1p2 + tmp2p2;
var tmp12p2 = tmp1p2 - tmp2p2;
data[dataOff] = tmp10p2 + tmp11p2; /* phase 3 */
data[dataOff+32] = tmp10p2 - tmp11p2;
var z1p2 = (tmp12p2 + tmp13p2) * 0.707106781; /* c4 */
data[dataOff+16] = tmp13p2 + z1p2; /* phase 5 */
data[dataOff+48] = tmp13p2 - z1p2;
/* Odd part */
tmp10p2 = tmp4p2 + tmp5p2; /* phase 2 */
tmp11p2 = tmp5p2 + tmp6p2;
tmp12p2 = tmp6p2 + tmp7p2;
/* The rotator is modified from fig 4-8 to avoid extra negations. */
var z5p2 = (tmp10p2 - tmp12p2) * 0.382683433; /* c6 */
var z2p2 = 0.541196100 * tmp10p2 + z5p2; /* c2-c6 */
var z4p2 = 1.306562965 * tmp12p2 + z5p2; /* c2+c6 */
var z3p2 = tmp11p2 * 0.707106781; /* c4 */
var z11p2 = tmp7p2 + z3p2; /* phase 5 */
var z13p2 = tmp7p2 - z3p2;
data[dataOff+40] = z13p2 + z2p2; /* phase 6 */
data[dataOff+24] = z13p2 - z2p2;
data[dataOff+ 8] = z11p2 + z4p2;
data[dataOff+56] = z11p2 - z4p2;
dataOff++; /* advance pointer to next column */
}
// Quantize/descale the coefficients
var fDCTQuant;
for (i=0; i<I64; ++i)
{
// Apply the quantization and scaling factor & Round to nearest integer
fDCTQuant = data[i]*fdtbl[i];
outputfDCTQuant[i] = (fDCTQuant > 0.0) ? ((fDCTQuant + 0.5)|0) : ((fDCTQuant - 0.5)|0);
//outputfDCTQuant[i] = fround(fDCTQuant);
}
return outputfDCTQuant;
}
function writeAPP0()
{
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
}
function writeSOF0(width, height)
{
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
}
function writeDQT()
{
writeWord(0xFFDB); // marker
writeWord(132); // length
writeByte(0);
for (var i=0; i<64; i++) {
writeByte(YTable[i]);
}
writeByte(1);
for (var j=0; j<64; j++) {
writeByte(UVTable[j]);
}
}
function writeDHT()
{
writeWord(0xFFC4); // marker
writeWord(0x01A2); // length
writeByte(0); // HTYDCinfo
for (var i=0; i<16; i++) {
writeByte(std_dc_luminance_nrcodes[i+1]);
}
for (var j=0; j<=11; j++) {
writeByte(std_dc_luminance_values[j]);
}
writeByte(0x10); // HTYACinfo
for (var k=0; k<16; k++) {
writeByte(std_ac_luminance_nrcodes[k+1]);
}
for (var l=0; l<=161; l++) {
writeByte(std_ac_luminance_values[l]);
}
writeByte(1); // HTUDCinfo
for (var m=0; m<16; m++) {
writeByte(std_dc_chrominance_nrcodes[m+1]);
}
for (var n=0; n<=11; n++) {
writeByte(std_dc_chrominance_values[n]);
}
writeByte(0x11); // HTUACinfo
for (var o=0; o<16; o++) {
writeByte(std_ac_chrominance_nrcodes[o+1]);
}
for (var p=0; p<=161; p++) {
writeByte(std_ac_chrominance_values[p]);
}
}
function writeSOS()
{
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
}
function processDU(CDU, fdtbl, DC, HTDC, HTAC){
var EOB = HTAC[0x00];
var M16zeroes = HTAC[0xF0];
var pos;
const I16 = 16;
const I63 = 63;
const I64 = 64;
var DU_DCT = fDCTQuant(CDU, fdtbl);
//ZigZag reorder
for (var j=0;j<I64;++j) {
DU[ZigZag[j]]=DU_DCT[j];
}
var Diff = DU[0] - DC; DC = DU[0];
//Encode DC
if (Diff==0) {
writeBits(HTDC[0]); // Diff might be 0
} else {
pos = 32767+Diff;
writeBits(HTDC[category[pos]]);
writeBits(bitcode[pos]);
}
//Encode ACs
var end0pos = 63; // was const... which is crazy
for (; (end0pos>0)&&(DU[end0pos]==0); end0pos--) {};
//end0pos = first element in reverse order !=0
if ( end0pos == 0) {
writeBits(EOB);
return DC;
}
var i = 1;
var lng;
while ( i <= end0pos ) {
var startpos = i;
for (; (DU[i]==0) && (i<=end0pos); ++i) {}
var nrzeroes = i-startpos;
if ( nrzeroes >= I16 ) {
lng = nrzeroes>>4;
for (var nrmarker=1; nrmarker <= lng; ++nrmarker)
writeBits(M16zeroes);
nrzeroes = nrzeroes&0xF;
}
pos = 32767+DU[i];
writeBits(HTAC[(nrzeroes<<4)+category[pos]]);
writeBits(bitcode[pos]);
i++;
}
if ( end0pos != I63 ) {
writeBits(EOB);
}
return DC;
}
function initCharLookupTable(){
var sfcc = String.fromCharCode;
for(var i=0; i < 256; i++){ ///// ACHTUNG // 255
clt[i] = sfcc(i);
}
}
this.encode = function(image,quality) // image data object
{
var time_start = new Date().getTime();
if(quality) setQuality(quality);
// Initialize bit writer
byteout = new Array();
bytenew=0;
bytepos=7;
// Add JPEG headers
writeWord(0xFFD8); // SOI
writeAPP0();
writeDQT();
writeSOF0(image.width,image.height);
writeDHT();
writeSOS();
// Encode 8x8 macroblocks
var DCY=0;
var DCU=0;
var DCV=0;
bytenew=0;
bytepos=7;
this.encode.displayName = "_encode_";
var imageData = image.data;
var width = image.width;
var height = image.height;
var quadWidth = width*4;
var tripleWidth = width*3;
var x, y = 0;
var r, g, b;
var start,p, col,row,pos;
while(y < height){
x = 0;
while(x < quadWidth){
start = quadWidth * y + x;
p = start;
col = -1;
row = 0;
for(pos=0; pos < 64; pos++){
row = pos >> 3;// /8
col = ( pos & 7 ) * 4; // %8
p = start + ( row * quadWidth ) + col;
if(y+row >= height){ // padding bottom
p-= (quadWidth*(y+1+row-height));
}
if(x+col >= quadWidth){ // padding right
p-= ((x+col) - quadWidth +4)
}
r = imageData[ p++ ];
g = imageData[ p++ ];
b = imageData[ p++ ];
/* // calculate YUV values dynamically
YDU[pos]=((( 0.29900)*r+( 0.58700)*g+( 0.11400)*b))-128; //-0x80
UDU[pos]=(((-0.16874)*r+(-0.33126)*g+( 0.50000)*b));
VDU[pos]=((( 0.50000)*r+(-0.41869)*g+(-0.08131)*b));
*/
// use lookup table (slightly faster)
YDU[pos] = ((RGB_YUV_TABLE[r] + RGB_YUV_TABLE[(g + 256)>>0] + RGB_YUV_TABLE[(b + 512)>>0]) >> 16)-128;
UDU[pos] = ((RGB_YUV_TABLE[(r + 768)>>0] + RGB_YUV_TABLE[(g + 1024)>>0] + RGB_YUV_TABLE[(b + 1280)>>0]) >> 16)-128;
VDU[pos] = ((RGB_YUV_TABLE[(r + 1280)>>0] + RGB_YUV_TABLE[(g + 1536)>>0] + RGB_YUV_TABLE[(b + 1792)>>0]) >> 16)-128;
}
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);
x+=32;
}
y+=8;
}
////////////////////////////////////////////////////////////////
// Do the bit alignment of the EOI marker
if ( bytepos >= 0 ) {
var fillbits = [];
fillbits[1] = bytepos+1;
fillbits[0] = (1<<(bytepos+1))-1;
writeBits(fillbits);
}
writeWord(0xFFD9); //EOI
var jpegDataUri = 'data:image/jpeg;base64,' + btoa(byteout.join(''));
byteout = [];
// benchmarking
var duration = new Date().getTime() - time_start;
console.log('Encoding time: '+ duration + 'ms');
//
return jpegDataUri
}
function setQuality(quality){
if (quality <= 0) {
quality = 1;
}
if (quality > 100) {
quality = 100;
}
if(currentQuality == quality) return // don't recalc if unchanged
var sf = 0;
if (quality < 50) {
sf = Math.floor(5000 / quality);
} else {
sf = Math.floor(200 - quality*2);
}
initQuantTables(sf);
currentQuality = quality;
console.log('Quality set to: '+quality +'%');
}
function init(){
var time_start = new Date().getTime();
if(!quality) quality = 50;
// Create tables
initCharLookupTable()
initHuffmanTbl();
initCategoryNumber();
initRGBYUVTable();
setQuality(quality);
var duration = new Date().getTime() - time_start;
console.log('Initialization '+ duration + 'ms');
}
init();
};
// helper function to get the imageData of an existing image on the current page.
function getImageDataFromImage(idOrElement){
var theImg = (typeof(idOrElement)=='string')? document.getElementById(idOrElement):idOrElement;
var cvs = document.createElement('canvas');
cvs.width = theImg.width;
cvs.height = theImg.height;
var ctx = cvs.getContext("2d");
ctx.drawImage(theImg,0,0);
return (ctx.getImageData(0, 0, cvs.width, cvs.height));
}
/*
function init(qu){
var theImg = document.getElementById('testimage');
var cvs = document.createElement('canvas');
cvs.width = theImg.width;
cvs.height = theImg.height;
//document.body.appendChild(cvs);
var ctx = cvs.getContext("2d");
ctx.drawImage(theImg,0,0);
var theImgData = (ctx.getImageData(0, 0, cvs.width, cvs.height));
var jpegURI = encoder.encode(theImgData,qu);
var img = document.createElement('img');
img.src = jpegURI;
document.body.appendChild(img);
}
*/