Mercurial > hg > orthanc-webviewer
diff WebApplication/jpeg-decoder.js @ 0:02f7a0400a91
initial commit
author | Sebastien Jodogne <s.jodogne@gmail.com> |
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date | Wed, 25 Feb 2015 13:45:35 +0100 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/WebApplication/jpeg-decoder.js Wed Feb 25 13:45:35 2015 +0100 @@ -0,0 +1,984 @@ +/** + * SOURCE: https://github.com/notmasteryet/jpgjs/blob/master/jpg.js + **/ + + +/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- / +/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */ +/* + Copyright 2011 notmasteryet + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. +*/ + +// - The JPEG specification can be found in the ITU CCITT Recommendation T.81 +// (www.w3.org/Graphics/JPEG/itu-t81.pdf) +// - The JFIF specification can be found in the JPEG File Interchange Format +// (www.w3.org/Graphics/JPEG/jfif3.pdf) +// - The Adobe Application-Specific JPEG markers in the Supporting the DCT Filters +// in PostScript Level 2, Technical Note #5116 +// (partners.adobe.com/public/developer/en/ps/sdk/5116.DCT_Filter.pdf) + +var JpegImage = (function jpegImage() { + "use strict"; + var dctZigZag = new Int32Array([ + 0, + 1, 8, + 16, 9, 2, + 3, 10, 17, 24, + 32, 25, 18, 11, 4, + 5, 12, 19, 26, 33, 40, + 48, 41, 34, 27, 20, 13, 6, + 7, 14, 21, 28, 35, 42, 49, 56, + 57, 50, 43, 36, 29, 22, 15, + 23, 30, 37, 44, 51, 58, + 59, 52, 45, 38, 31, + 39, 46, 53, 60, + 61, 54, 47, + 55, 62, + 63 + ]); + + var dctCos1 = 4017 // cos(pi/16) + var dctSin1 = 799 // sin(pi/16) + var dctCos3 = 3406 // cos(3*pi/16) + var dctSin3 = 2276 // sin(3*pi/16) + var dctCos6 = 1567 // cos(6*pi/16) + var dctSin6 = 3784 // sin(6*pi/16) + var dctSqrt2 = 5793 // sqrt(2) + var dctSqrt1d2 = 2896 // sqrt(2) / 2 + + function constructor() { + } + + function buildHuffmanTable(codeLengths, values) { + var k = 0, code = [], i, j, length = 16; + while (length > 0 && !codeLengths[length - 1]) + length--; + code.push({children: [], index: 0}); + var p = code[0], q; + for (i = 0; i < length; i++) { + for (j = 0; j < codeLengths[i]; j++) { + p = code.pop(); + p.children[p.index] = values[k]; + while (p.index > 0) { + p = code.pop(); + } + p.index++; + code.push(p); + while (code.length <= i) { + code.push(q = {children: [], index: 0}); + p.children[p.index] = q.children; + p = q; + } + k++; + } + if (i + 1 < length) { + // p here points to last code + code.push(q = {children: [], index: 0}); + p.children[p.index] = q.children; + p = q; + } + } + return code[0].children; + } + + function getBlockBufferOffset(component, row, col) { + return 64 * ((component.blocksPerLine + 1) * row + col); + } + + function decodeScan(data, offset, + frame, components, resetInterval, + spectralStart, spectralEnd, + successivePrev, successive) { + var precision = frame.precision; + var samplesPerLine = frame.samplesPerLine; + var scanLines = frame.scanLines; + var mcusPerLine = frame.mcusPerLine; + var progressive = frame.progressive; + var maxH = frame.maxH, maxV = frame.maxV; + + var startOffset = offset, bitsData = 0, bitsCount = 0; + + function readBit() { + if (bitsCount > 0) { + bitsCount--; + return (bitsData >> bitsCount) & 1; + } + bitsData = data[offset++]; + if (bitsData == 0xFF) { + var nextByte = data[offset++]; + if (nextByte) { + throw "unexpected marker: " + ((bitsData << 8) | nextByte).toString(16); + } + // unstuff 0 + } + bitsCount = 7; + return bitsData >>> 7; + } + + function decodeHuffman(tree) { + var node = tree; + var bit; + while ((bit = readBit()) !== null) { + node = node[bit]; + if (typeof node === 'number') + return node; + if (typeof node !== 'object') + throw "invalid huffman sequence"; + } + return null; + } + + function receive(length) { + var n = 0; + while (length > 0) { + var bit = readBit(); + if (bit === null) return; + n = (n << 1) | bit; + length--; + } + return n; + } + + function receiveAndExtend(length) { + var n = receive(length); + if (n >= 1 << (length - 1)) + return n; + return n + (-1 << length) + 1; + } + + function decodeBaseline(component, offset) { + var t = decodeHuffman(component.huffmanTableDC); + var diff = t === 0 ? 0 : receiveAndExtend(t); + component.blockData[offset] = (component.pred += diff); + var k = 1; + while (k < 64) { + var rs = decodeHuffman(component.huffmanTableAC); + var s = rs & 15, r = rs >> 4; + if (s === 0) { + if (r < 15) + break; + k += 16; + continue; + } + k += r; + var z = dctZigZag[k]; + component.blockData[offset + z] = receiveAndExtend(s); + k++; + } + } + + function decodeDCFirst(component, offset) { + var t = decodeHuffman(component.huffmanTableDC); + var diff = t === 0 ? 0 : (receiveAndExtend(t) << successive); + component.blockData[offset] = (component.pred += diff); + } + + function decodeDCSuccessive(component, offset) { + component.blockData[offset] |= readBit() << successive; + } + + var eobrun = 0; + function decodeACFirst(component, offset) { + if (eobrun > 0) { + eobrun--; + return; + } + var k = spectralStart, e = spectralEnd; + while (k <= e) { + var rs = decodeHuffman(component.huffmanTableAC); + var s = rs & 15, r = rs >> 4; + if (s === 0) { + if (r < 15) { + eobrun = receive(r) + (1 << r) - 1; + break; + } + k += 16; + continue; + } + k += r; + var z = dctZigZag[k]; + component.blockData[offset + z] = receiveAndExtend(s) * (1 << successive); + k++; + } + } + + var successiveACState = 0, successiveACNextValue; + function decodeACSuccessive(component, offset) { + var k = spectralStart, e = spectralEnd, r = 0; + while (k <= e) { + var z = dctZigZag[k]; + switch (successiveACState) { + case 0: // initial state + var rs = decodeHuffman(component.huffmanTableAC); + var s = rs & 15, r = rs >> 4; + if (s === 0) { + if (r < 15) { + eobrun = receive(r) + (1 << r); + successiveACState = 4; + } else { + r = 16; + successiveACState = 1; + } + } else { + if (s !== 1) + throw "invalid ACn encoding"; + successiveACNextValue = receiveAndExtend(s); + successiveACState = r ? 2 : 3; + } + continue; + case 1: // skipping r zero items + case 2: + if (component.blockData[offset + z]) { + component.blockData[offset + z] += (readBit() << successive); + } else { + r--; + if (r === 0) + successiveACState = successiveACState == 2 ? 3 : 0; + } + break; + case 3: // set value for a zero item + if (component.blockData[offset + z]) { + component.blockData[offset + z] += (readBit() << successive); + } else { + component.blockData[offset + z] = successiveACNextValue << successive; + successiveACState = 0; + } + break; + case 4: // eob + if (component.blockData[offset + z]) { + component.blockData[offset + z] += (readBit() << successive); + } + break; + } + k++; + } + if (successiveACState === 4) { + eobrun--; + if (eobrun === 0) + successiveACState = 0; + } + } + + function decodeMcu(component, decode, mcu, row, col) { + var mcuRow = (mcu / mcusPerLine) | 0; + var mcuCol = mcu % mcusPerLine; + var blockRow = mcuRow * component.v + row; + var blockCol = mcuCol * component.h + col; + var offset = getBlockBufferOffset(component, blockRow, blockCol); + decode(component, offset); + } + + function decodeBlock(component, decode, mcu) { + var blockRow = (mcu / component.blocksPerLine) | 0; + var blockCol = mcu % component.blocksPerLine; + var offset = getBlockBufferOffset(component, blockRow, blockCol); + decode(component, offset); + } + + var componentsLength = components.length; + var component, i, j, k, n; + var decodeFn; + if (progressive) { + if (spectralStart === 0) + decodeFn = successivePrev === 0 ? decodeDCFirst : decodeDCSuccessive; + else + decodeFn = successivePrev === 0 ? decodeACFirst : decodeACSuccessive; + } else { + decodeFn = decodeBaseline; + } + + var mcu = 0, marker; + var mcuExpected; + if (componentsLength == 1) { + mcuExpected = components[0].blocksPerLine * components[0].blocksPerColumn; + } else { + mcuExpected = mcusPerLine * frame.mcusPerColumn; + } + if (!resetInterval) { + resetInterval = mcuExpected; + } + + var h, v; + while (mcu < mcuExpected) { + // reset interval stuff + for (i = 0; i < componentsLength; i++) { + components[i].pred = 0; + } + eobrun = 0; + + if (componentsLength == 1) { + component = components[0]; + for (n = 0; n < resetInterval; n++) { + decodeBlock(component, decodeFn, mcu); + mcu++; + } + } else { + for (n = 0; n < resetInterval; n++) { + for (i = 0; i < componentsLength; i++) { + component = components[i]; + h = component.h; + v = component.v; + for (j = 0; j < v; j++) { + for (k = 0; k < h; k++) { + decodeMcu(component, decodeFn, mcu, j, k); + } + } + } + mcu++; + } + } + + // find marker + bitsCount = 0; + marker = (data[offset] << 8) | data[offset + 1]; + if (marker <= 0xFF00) { + throw "marker was not found"; + } + + if (marker >= 0xFFD0 && marker <= 0xFFD7) { // RSTx + offset += 2; + } else { + break; + } + } + + return offset - startOffset; + } + + // A port of poppler's IDCT method which in turn is taken from: + // Christoph Loeffler, Adriaan Ligtenberg, George S. Moschytz, + // "Practical Fast 1-D DCT Algorithms with 11 Multiplications", + // IEEE Intl. Conf. on Acoustics, Speech & Signal Processing, 1989, + // 988-991. + function quantizeAndInverse(component, blockBufferOffset, p) { + var qt = component.quantizationTable; + var v0, v1, v2, v3, v4, v5, v6, v7, t; + var i; + + // dequant + for (i = 0; i < 64; i++) { + p[i] = component.blockData[blockBufferOffset + i] * qt[i]; + } + + // inverse DCT on rows + for (i = 0; i < 8; ++i) { + var row = 8 * i; + + // check for all-zero AC coefficients + if (p[1 + row] == 0 && p[2 + row] == 0 && p[3 + row] == 0 && + p[4 + row] == 0 && p[5 + row] == 0 && p[6 + row] == 0 && + p[7 + row] == 0) { + t = (dctSqrt2 * p[0 + row] + 512) >> 10; + p[0 + row] = t; + p[1 + row] = t; + p[2 + row] = t; + p[3 + row] = t; + p[4 + row] = t; + p[5 + row] = t; + p[6 + row] = t; + p[7 + row] = t; + continue; + } + + // stage 4 + v0 = (dctSqrt2 * p[0 + row] + 128) >> 8; + v1 = (dctSqrt2 * p[4 + row] + 128) >> 8; + v2 = p[2 + row]; + v3 = p[6 + row]; + v4 = (dctSqrt1d2 * (p[1 + row] - p[7 + row]) + 128) >> 8; + v7 = (dctSqrt1d2 * (p[1 + row] + p[7 + row]) + 128) >> 8; + v5 = p[3 + row] << 4; + v6 = p[5 + row] << 4; + + // stage 3 + t = (v0 - v1+ 1) >> 1; + v0 = (v0 + v1 + 1) >> 1; + v1 = t; + t = (v2 * dctSin6 + v3 * dctCos6 + 128) >> 8; + v2 = (v2 * dctCos6 - v3 * dctSin6 + 128) >> 8; + v3 = t; + t = (v4 - v6 + 1) >> 1; + v4 = (v4 + v6 + 1) >> 1; + v6 = t; + t = (v7 + v5 + 1) >> 1; + v5 = (v7 - v5 + 1) >> 1; + v7 = t; + + // stage 2 + t = (v0 - v3 + 1) >> 1; + v0 = (v0 + v3 + 1) >> 1; + v3 = t; + t = (v1 - v2 + 1) >> 1; + v1 = (v1 + v2 + 1) >> 1; + v2 = t; + t = (v4 * dctSin3 + v7 * dctCos3 + 2048) >> 12; + v4 = (v4 * dctCos3 - v7 * dctSin3 + 2048) >> 12; + v7 = t; + t = (v5 * dctSin1 + v6 * dctCos1 + 2048) >> 12; + v5 = (v5 * dctCos1 - v6 * dctSin1 + 2048) >> 12; + v6 = t; + + // stage 1 + p[0 + row] = v0 + v7; + p[7 + row] = v0 - v7; + p[1 + row] = v1 + v6; + p[6 + row] = v1 - v6; + p[2 + row] = v2 + v5; + p[5 + row] = v2 - v5; + p[3 + row] = v3 + v4; + p[4 + row] = v3 - v4; + } + + // inverse DCT on columns + for (i = 0; i < 8; ++i) { + var col = i; + + // check for all-zero AC coefficients + if (p[1*8 + col] == 0 && p[2*8 + col] == 0 && p[3*8 + col] == 0 && + p[4*8 + col] == 0 && p[5*8 + col] == 0 && p[6*8 + col] == 0 && + p[7*8 + col] == 0) { + t = (dctSqrt2 * p[i+0] + 8192) >> 14; + p[0*8 + col] = t; + p[1*8 + col] = t; + p[2*8 + col] = t; + p[3*8 + col] = t; + p[4*8 + col] = t; + p[5*8 + col] = t; + p[6*8 + col] = t; + p[7*8 + col] = t; + continue; + } + + // stage 4 + v0 = (dctSqrt2 * p[0*8 + col] + 2048) >> 12; + v1 = (dctSqrt2 * p[4*8 + col] + 2048) >> 12; + v2 = p[2*8 + col]; + v3 = p[6*8 + col]; + v4 = (dctSqrt1d2 * (p[1*8 + col] - p[7*8 + col]) + 2048) >> 12; + v7 = (dctSqrt1d2 * (p[1*8 + col] + p[7*8 + col]) + 2048) >> 12; + v5 = p[3*8 + col]; + v6 = p[5*8 + col]; + + // stage 3 + t = (v0 - v1 + 1) >> 1; + v0 = (v0 + v1 + 1) >> 1; + v1 = t; + t = (v2 * dctSin6 + v3 * dctCos6 + 2048) >> 12; + v2 = (v2 * dctCos6 - v3 * dctSin6 + 2048) >> 12; + v3 = t; + t = (v4 - v6 + 1) >> 1; + v4 = (v4 + v6 + 1) >> 1; + v6 = t; + t = (v7 + v5 + 1) >> 1; + v5 = (v7 - v5 + 1) >> 1; + v7 = t; + + // stage 2 + t = (v0 - v3 + 1) >> 1; + v0 = (v0 + v3 + 1) >> 1; + v3 = t; + t = (v1 - v2 + 1) >> 1; + v1 = (v1 + v2 + 1) >> 1; + v2 = t; + t = (v4 * dctSin3 + v7 * dctCos3 + 2048) >> 12; + v4 = (v4 * dctCos3 - v7 * dctSin3 + 2048) >> 12; + v7 = t; + t = (v5 * dctSin1 + v6 * dctCos1 + 2048) >> 12; + v5 = (v5 * dctCos1 - v6 * dctSin1 + 2048) >> 12; + v6 = t; + + // stage 1 + p[0*8 + col] = v0 + v7; + p[7*8 + col] = v0 - v7; + p[1*8 + col] = v1 + v6; + p[6*8 + col] = v1 - v6; + p[2*8 + col] = v2 + v5; + p[5*8 + col] = v2 - v5; + p[3*8 + col] = v3 + v4; + p[4*8 + col] = v3 - v4; + } + + // convert to 8-bit integers + for (i = 0; i < 64; ++i) { + var index = blockBufferOffset + i; + var q = p[i]; + q = (q <= -2056) ? 0 : (q >= 2024) ? 255 : (q + 2056) >> 4; + component.blockData[index] = q; + } + } + + function buildComponentData(frame, component) { + var lines = []; + var blocksPerLine = component.blocksPerLine; + var blocksPerColumn = component.blocksPerColumn; + var samplesPerLine = blocksPerLine << 3; + var computationBuffer = new Int32Array(64); + + var i, j, ll = 0; + for (var blockRow = 0; blockRow < blocksPerColumn; blockRow++) { + for (var blockCol = 0; blockCol < blocksPerLine; blockCol++) { + var offset = getBlockBufferOffset(component, blockRow, blockCol) + quantizeAndInverse(component, offset, computationBuffer); + } + } + return component.blockData; + } + + function clampToUint8(a) { + return a <= 0 ? 0 : a >= 255 ? 255 : a | 0; + } + + constructor.prototype = { + load: function load(path) { + var handleData = (function(data) { + this.parse(data); + if (this.onload) + this.onload(); + }).bind(this); + + if (path.indexOf("data:") > -1) { + var offset = path.indexOf("base64,")+7; + var data = atob(path.substring(offset)); + var arr = new Uint8Array(data.length); + for (var i = data.length - 1; i >= 0; i--) { + arr[i] = data.charCodeAt(i); + } + handleData(data); + } else { + var xhr = new XMLHttpRequest(); + xhr.open("GET", path, true); + xhr.responseType = "arraybuffer"; + xhr.onload = (function() { + // TODO catch parse error + var data = new Uint8Array(xhr.response); + handleData(data); + }).bind(this); + xhr.send(null); + } + }, + + parse: function parse(data) { + + function readUint16() { + var value = (data[offset] << 8) | data[offset + 1]; + offset += 2; + return value; + } + + function readDataBlock() { + var length = readUint16(); + var array = data.subarray(offset, offset + length - 2); + offset += array.length; + return array; + } + + function prepareComponents(frame) { + var mcusPerLine = Math.ceil(frame.samplesPerLine / 8 / frame.maxH); + var mcusPerColumn = Math.ceil(frame.scanLines / 8 / frame.maxV); + for (var i = 0; i < frame.components.length; i++) { + component = frame.components[i]; + var blocksPerLine = Math.ceil(Math.ceil(frame.samplesPerLine / 8) * component.h / frame.maxH); + var blocksPerColumn = Math.ceil(Math.ceil(frame.scanLines / 8) * component.v / frame.maxV); + var blocksPerLineForMcu = mcusPerLine * component.h; + var blocksPerColumnForMcu = mcusPerColumn * component.v; + + var blocksBufferSize = 64 * blocksPerColumnForMcu + * (blocksPerLineForMcu + 1); + component.blockData = new Int16Array(blocksBufferSize); + component.blocksPerLine = blocksPerLine; + component.blocksPerColumn = blocksPerColumn; + } + frame.mcusPerLine = mcusPerLine; + frame.mcusPerColumn = mcusPerColumn; + } + + var offset = 0, length = data.length; + var jfif = null; + var adobe = null; + var pixels = null; + var frame, resetInterval; + var quantizationTables = []; + var huffmanTablesAC = [], huffmanTablesDC = []; + var fileMarker = readUint16(); + if (fileMarker != 0xFFD8) { // SOI (Start of Image) + throw "SOI not found"; + } + + fileMarker = readUint16(); + while (fileMarker != 0xFFD9) { // EOI (End of image) + var i, j, l; + switch(fileMarker) { + case 0xFFE0: // APP0 (Application Specific) + case 0xFFE1: // APP1 + case 0xFFE2: // APP2 + case 0xFFE3: // APP3 + case 0xFFE4: // APP4 + case 0xFFE5: // APP5 + case 0xFFE6: // APP6 + case 0xFFE7: // APP7 + case 0xFFE8: // APP8 + case 0xFFE9: // APP9 + case 0xFFEA: // APP10 + case 0xFFEB: // APP11 + case 0xFFEC: // APP12 + case 0xFFED: // APP13 + case 0xFFEE: // APP14 + case 0xFFEF: // APP15 + case 0xFFFE: // COM (Comment) + var appData = readDataBlock(); + + if (fileMarker === 0xFFE0) { + if (appData[0] === 0x4A && appData[1] === 0x46 && appData[2] === 0x49 && + appData[3] === 0x46 && appData[4] === 0) { // 'JFIF\x00' + jfif = { + version: { major: appData[5], minor: appData[6] }, + densityUnits: appData[7], + xDensity: (appData[8] << 8) | appData[9], + yDensity: (appData[10] << 8) | appData[11], + thumbWidth: appData[12], + thumbHeight: appData[13], + thumbData: appData.subarray(14, 14 + 3 * appData[12] * appData[13]) + }; + } + } + // TODO APP1 - Exif + if (fileMarker === 0xFFEE) { + if (appData[0] === 0x41 && appData[1] === 0x64 && appData[2] === 0x6F && + appData[3] === 0x62 && appData[4] === 0x65 && appData[5] === 0) { // 'Adobe\x00' + adobe = { + version: appData[6], + flags0: (appData[7] << 8) | appData[8], + flags1: (appData[9] << 8) | appData[10], + transformCode: appData[11] + }; + } + } + break; + + case 0xFFDB: // DQT (Define Quantization Tables) + var quantizationTablesLength = readUint16(); + var quantizationTablesEnd = quantizationTablesLength + offset - 2; + while (offset < quantizationTablesEnd) { + var quantizationTableSpec = data[offset++]; + var tableData = new Int32Array(64); + if ((quantizationTableSpec >> 4) === 0) { // 8 bit values + for (j = 0; j < 64; j++) { + var z = dctZigZag[j]; + tableData[z] = data[offset++]; + } + } else if ((quantizationTableSpec >> 4) === 1) { //16 bit + for (j = 0; j < 64; j++) { + var z = dctZigZag[j]; + tableData[z] = readUint16(); + } + } else + throw "DQT: invalid table spec"; + quantizationTables[quantizationTableSpec & 15] = tableData; + } + break; + + case 0xFFC0: // SOF0 (Start of Frame, Baseline DCT) + case 0xFFC1: // SOF1 (Start of Frame, Extended DCT) + case 0xFFC2: // SOF2 (Start of Frame, Progressive DCT) + if (frame) { + throw "Only single frame JPEGs supported"; + } + readUint16(); // skip data length + frame = {}; + frame.extended = (fileMarker === 0xFFC1); + frame.progressive = (fileMarker === 0xFFC2); + frame.precision = data[offset++]; + frame.scanLines = readUint16(); + frame.samplesPerLine = readUint16(); + frame.components = []; + frame.componentIds = {}; + var componentsCount = data[offset++], componentId; + var maxH = 0, maxV = 0; + for (i = 0; i < componentsCount; i++) { + componentId = data[offset]; + var h = data[offset + 1] >> 4; + var v = data[offset + 1] & 15; + if (maxH < h) maxH = h; + if (maxV < v) maxV = v; + var qId = data[offset + 2]; + var l = frame.components.push({ + h: h, + v: v, + quantizationTable: quantizationTables[qId] + }); + frame.componentIds[componentId] = l - 1; + offset += 3; + } + frame.maxH = maxH; + frame.maxV = maxV; + prepareComponents(frame); + break; + + case 0xFFC4: // DHT (Define Huffman Tables) + var huffmanLength = readUint16(); + for (i = 2; i < huffmanLength;) { + var huffmanTableSpec = data[offset++]; + var codeLengths = new Uint8Array(16); + var codeLengthSum = 0; + for (j = 0; j < 16; j++, offset++) + codeLengthSum += (codeLengths[j] = data[offset]); + var huffmanValues = new Uint8Array(codeLengthSum); + for (j = 0; j < codeLengthSum; j++, offset++) + huffmanValues[j] = data[offset]; + i += 17 + codeLengthSum; + + ((huffmanTableSpec >> 4) === 0 ? + huffmanTablesDC : huffmanTablesAC)[huffmanTableSpec & 15] = + buildHuffmanTable(codeLengths, huffmanValues); + } + break; + + case 0xFFDD: // DRI (Define Restart Interval) + readUint16(); // skip data length + resetInterval = readUint16(); + break; + + case 0xFFDA: // SOS (Start of Scan) + var scanLength = readUint16(); + var selectorsCount = data[offset++]; + var components = [], component; + for (i = 0; i < selectorsCount; i++) { + var componentIndex = frame.componentIds[data[offset++]]; + component = frame.components[componentIndex]; + var tableSpec = data[offset++]; + component.huffmanTableDC = huffmanTablesDC[tableSpec >> 4]; + component.huffmanTableAC = huffmanTablesAC[tableSpec & 15]; + components.push(component); + } + var spectralStart = data[offset++]; + var spectralEnd = data[offset++]; + var successiveApproximation = data[offset++]; + var processed = decodeScan(data, offset, + frame, components, resetInterval, + spectralStart, spectralEnd, + successiveApproximation >> 4, successiveApproximation & 15); + offset += processed; + break; + default: + if (data[offset - 3] == 0xFF && + data[offset - 2] >= 0xC0 && data[offset - 2] <= 0xFE) { + // could be incorrect encoding -- last 0xFF byte of the previous + // block was eaten by the encoder + offset -= 3; + break; + } + throw "unknown JPEG marker " + fileMarker.toString(16); + } + fileMarker = readUint16(); + } + + this.width = frame.samplesPerLine; + this.height = frame.scanLines; + this.jfif = jfif; + this.adobe = adobe; + this.components = []; + for (var i = 0; i < frame.components.length; i++) { + var component = frame.components[i]; + this.components.push({ + output: buildComponentData(frame, component), + scaleX: component.h / frame.maxH, + scaleY: component.v / frame.maxV, + blocksPerLine: component.blocksPerLine, + blocksPerColumn: component.blocksPerColumn + }); + } + }, + + getData: function getData(width, height) { + var scaleX = this.width / width, scaleY = this.height / height; + + var component, componentScaleX, componentScaleY; + var x, y, i; + var offset = 0; + var Y, Cb, Cr, K, C, M, Ye, R, G, B; + var colorTransform; + var numComponents = this.components.length; + var dataLength = width * height * numComponents; + var data = new Uint8Array(dataLength); + var componentLine; + + // lineData is reused for all components. Assume first component is + // the biggest + var lineData = new Uint8Array((this.components[0].blocksPerLine << 3) * + this.components[0].blocksPerColumn * 8); + + // First construct image data ... + for (i = 0; i < numComponents; i++) { + component = this.components[i]; + var blocksPerLine = component.blocksPerLine; + var blocksPerColumn = component.blocksPerColumn; + var samplesPerLine = blocksPerLine << 3; + + var j, k, ll = 0; + var lineOffset = 0; + for (var blockRow = 0; blockRow < blocksPerColumn; blockRow++) { + var scanLine = blockRow << 3; + for (var blockCol = 0; blockCol < blocksPerLine; blockCol++) { + var bufferOffset = getBlockBufferOffset(component, blockRow, blockCol); + var offset = 0, sample = blockCol << 3; + for (j = 0; j < 8; j++) { + var lineOffset = (scanLine + j) * samplesPerLine; + for (k = 0; k < 8; k++) { + lineData[lineOffset + sample + k] = + component.output[bufferOffset + offset++]; + } + } + } + } + + componentScaleX = component.scaleX * scaleX; + componentScaleY = component.scaleY * scaleY; + offset = i; + + var cx, cy; + var index; + for (y = 0; y < height; y++) { + for (x = 0; x < width; x++) { + cy = 0 | (y * componentScaleY); + cx = 0 | (x * componentScaleX); + index = cy * samplesPerLine + cx; + data[offset] = lineData[index]; + offset += numComponents; + } + } + } + + // ... then transform colors, if necessary + switch (numComponents) { + case 1: case 2: break; + // no color conversion for one or two compoenents + + case 3: + // The default transform for three components is true + colorTransform = true; + // The adobe transform marker overrides any previous setting + if (this.adobe && this.adobe.transformCode) + colorTransform = true; + else if (typeof this.colorTransform !== 'undefined') + colorTransform = !!this.colorTransform; + + if (colorTransform) { + for (i = 0; i < dataLength; i += numComponents) { + Y = data[i ]; + Cb = data[i + 1]; + Cr = data[i + 2]; + + R = clampToUint8(Y - 179.456 + 1.402 * Cr); + G = clampToUint8(Y + 135.459 - 0.344 * Cb - 0.714 * Cr); + B = clampToUint8(Y - 226.816 + 1.772 * Cb); + + data[i ] = R; + data[i + 1] = G; + data[i + 2] = B; + } + } + break; + case 4: + if (!this.adobe) + throw 'Unsupported color mode (4 components)'; + // The default transform for four components is false + colorTransform = false; + // The adobe transform marker overrides any previous setting + if (this.adobe && this.adobe.transformCode) + colorTransform = true; + else if (typeof this.colorTransform !== 'undefined') + colorTransform = !!this.colorTransform; + + if (colorTransform) { + for (i = 0; i < dataLength; i += numComponents) { + Y = data[i]; + Cb = data[i + 1]; + Cr = data[i + 2]; + + C = clampToUint8(434.456 - Y - 1.402 * Cr); + M = clampToUint8(119.541 - Y + 0.344 * Cb + 0.714 * Cr); + Y = clampToUint8(481.816 - Y - 1.772 * Cb); + + data[i ] = C; + data[i + 1] = M; + data[i + 2] = Y; + // K is unchanged + } + } + break; + default: + throw 'Unsupported color mode'; + } + return data; + }, + copyToImageData: function copyToImageData(imageData) { + var width = imageData.width, height = imageData.height; + var imageDataBytes = width * height * 4; + var imageDataArray = imageData.data; + var data = this.getData(width, height); + var i = 0, j = 0, k0, k1; + var Y, K, C, M, R, G, B; + switch (this.components.length) { + case 1: + while (j < imageDataBytes) { + Y = data[i++]; + + imageDataArray[j++] = Y; + imageDataArray[j++] = Y; + imageDataArray[j++] = Y; + imageDataArray[j++] = 255; + } + break; + case 3: + while (j < imageDataBytes) { + R = data[i++]; + G = data[i++]; + B = data[i++]; + + imageDataArray[j++] = R; + imageDataArray[j++] = G; + imageDataArray[j++] = B; + imageDataArray[j++] = 255; + } + break; + case 4: + while (j < imageDataBytes) { + C = data[i++]; + M = data[i++]; + Y = data[i++]; + K = data[i++]; + + k0 = 255 - K; + k1 = k0 / 255; + + + R = clampToUint8(k0 - C * k1); + G = clampToUint8(k0 - M * k1); + B = clampToUint8(k0 - Y * k1); + + imageDataArray[j++] = R; + imageDataArray[j++] = G; + imageDataArray[j++] = B; + imageDataArray[j++] = 255; + } + break; + default: + throw 'Unsupported color mode'; + } + } + }; + + return constructor; +})();