962 lines
31 KiB
JavaScript
962 lines
31 KiB
JavaScript
/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- /
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/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
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/*
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Copyright 2011 notmasteryet
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// - The JPEG specification can be found in the ITU CCITT Recommendation T.81
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// (www.w3.org/Graphics/JPEG/itu-t81.pdf)
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// - The JFIF specification can be found in the JPEG File Interchange Format
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// (www.w3.org/Graphics/JPEG/jfif3.pdf)
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// - The Adobe Application-Specific JPEG markers in the Supporting the DCT Filters
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// in PostScript Level 2, Technical Note #5116
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// (partners.adobe.com/public/developer/en/ps/sdk/5116.DCT_Filter.pdf)
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var JpegImage = (function jpegImage() {
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"use strict";
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var dctZigZag = new Int32Array([
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0,
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1, 8,
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16, 9, 2,
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3, 10, 17, 24,
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32, 25, 18, 11, 4,
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5, 12, 19, 26, 33, 40,
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48, 41, 34, 27, 20, 13, 6,
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7, 14, 21, 28, 35, 42, 49, 56,
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57, 50, 43, 36, 29, 22, 15,
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23, 30, 37, 44, 51, 58,
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59, 52, 45, 38, 31,
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39, 46, 53, 60,
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61, 54, 47,
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55, 62,
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63
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]);
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var dctCos1 = 4017 // cos(pi/16)
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var dctSin1 = 799 // sin(pi/16)
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var dctCos3 = 3406 // cos(3*pi/16)
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var dctSin3 = 2276 // sin(3*pi/16)
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var dctCos6 = 1567 // cos(6*pi/16)
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var dctSin6 = 3784 // sin(6*pi/16)
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var dctSqrt2 = 5793 // sqrt(2)
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var dctSqrt1d2 = 2896 // sqrt(2) / 2
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function constructor() {
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}
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function buildHuffmanTable(codeLengths, values) {
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var k = 0, code = [], i, j, length = 16;
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while (length > 0 && !codeLengths[length - 1])
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length--;
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code.push({children: [], index: 0});
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var p = code[0], q;
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for (i = 0; i < length; i++) {
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for (j = 0; j < codeLengths[i]; j++) {
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p = code.pop();
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p.children[p.index] = values[k];
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while (p.index > 0) {
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p = code.pop();
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}
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p.index++;
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code.push(p);
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while (code.length <= i) {
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code.push(q = {children: [], index: 0});
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p.children[p.index] = q.children;
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p = q;
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}
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k++;
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}
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if (i + 1 < length) {
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// p here points to last code
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code.push(q = {children: [], index: 0});
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p.children[p.index] = q.children;
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p = q;
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}
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}
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return code[0].children;
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}
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function getBlockBufferOffset(component, row, col) {
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return 64 * ((component.blocksPerLine + 1) * row + col);
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}
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function decodeScan(data, offset,
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frame, components, resetInterval,
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spectralStart, spectralEnd,
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successivePrev, successive) {
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var precision = frame.precision;
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var samplesPerLine = frame.samplesPerLine;
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var scanLines = frame.scanLines;
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var mcusPerLine = frame.mcusPerLine;
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var progressive = frame.progressive;
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var maxH = frame.maxH, maxV = frame.maxV;
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var startOffset = offset, bitsData = 0, bitsCount = 0;
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function readBit() {
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if (bitsCount > 0) {
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bitsCount--;
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return (bitsData >> bitsCount) & 1;
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}
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bitsData = data[offset++];
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if (bitsData == 0xFF) {
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var nextByte = data[offset++];
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if (nextByte) {
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throw "unexpected marker: " + ((bitsData << 8) | nextByte).toString(16);
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}
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// unstuff 0
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}
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bitsCount = 7;
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return bitsData >>> 7;
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}
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function decodeHuffman(tree) {
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var node = tree;
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var bit;
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while ((bit = readBit()) !== null) {
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node = node[bit];
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if (typeof node === 'number')
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return node;
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if (typeof node !== 'object')
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throw "invalid huffman sequence";
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}
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return null;
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}
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function receive(length) {
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var n = 0;
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while (length > 0) {
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var bit = readBit();
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if (bit === null) return;
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n = (n << 1) | bit;
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length--;
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}
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return n;
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}
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function receiveAndExtend(length) {
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var n = receive(length);
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if (n >= 1 << (length - 1))
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return n;
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return n + (-1 << length) + 1;
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}
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function decodeBaseline(component, offset) {
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var t = decodeHuffman(component.huffmanTableDC);
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var diff = t === 0 ? 0 : receiveAndExtend(t);
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component.blockData[offset] = (component.pred += diff);
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var k = 1;
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while (k < 64) {
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var rs = decodeHuffman(component.huffmanTableAC);
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var s = rs & 15, r = rs >> 4;
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if (s === 0) {
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if (r < 15)
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break;
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k += 16;
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continue;
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}
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k += r;
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var z = dctZigZag[k];
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component.blockData[offset + z] = receiveAndExtend(s);
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k++;
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}
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}
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function decodeDCFirst(component, offset) {
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var t = decodeHuffman(component.huffmanTableDC);
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var diff = t === 0 ? 0 : (receiveAndExtend(t) << successive);
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component.blockData[offset] = (component.pred += diff);
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}
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function decodeDCSuccessive(component, offset) {
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component.blockData[offset] |= readBit() << successive;
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}
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var eobrun = 0;
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function decodeACFirst(component, offset) {
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if (eobrun > 0) {
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eobrun--;
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return;
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}
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var k = spectralStart, e = spectralEnd;
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while (k <= e) {
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var rs = decodeHuffman(component.huffmanTableAC);
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var s = rs & 15, r = rs >> 4;
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if (s === 0) {
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if (r < 15) {
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eobrun = receive(r) + (1 << r) - 1;
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break;
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}
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k += 16;
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continue;
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}
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k += r;
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var z = dctZigZag[k];
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component.blockData[offset + z] = receiveAndExtend(s) * (1 << successive);
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k++;
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}
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}
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var successiveACState = 0, successiveACNextValue;
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function decodeACSuccessive(component, offset) {
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var k = spectralStart, e = spectralEnd, r = 0;
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while (k <= e) {
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var z = dctZigZag[k];
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switch (successiveACState) {
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case 0: // initial state
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var rs = decodeHuffman(component.huffmanTableAC);
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var s = rs & 15, r = rs >> 4;
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if (s === 0) {
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if (r < 15) {
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eobrun = receive(r) + (1 << r);
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successiveACState = 4;
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} else {
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r = 16;
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successiveACState = 1;
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}
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} else {
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if (s !== 1)
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throw "invalid ACn encoding";
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successiveACNextValue = receiveAndExtend(s);
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successiveACState = r ? 2 : 3;
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}
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continue;
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case 1: // skipping r zero items
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case 2:
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if (component.blockData[offset + z]) {
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component.blockData[offset + z] += (readBit() << successive);
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} else {
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r--;
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if (r === 0)
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successiveACState = successiveACState == 2 ? 3 : 0;
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}
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break;
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case 3: // set value for a zero item
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if (component.blockData[offset + z]) {
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component.blockData[offset + z] += (readBit() << successive);
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} else {
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component.blockData[offset + z] = successiveACNextValue << successive;
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successiveACState = 0;
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}
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break;
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case 4: // eob
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if (component.blockData[offset + z]) {
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component.blockData[offset + z] += (readBit() << successive);
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}
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break;
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}
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k++;
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}
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if (successiveACState === 4) {
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eobrun--;
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if (eobrun === 0)
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successiveACState = 0;
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}
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}
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function decodeMcu(component, decode, mcu, row, col) {
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var mcuRow = (mcu / mcusPerLine) | 0;
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var mcuCol = mcu % mcusPerLine;
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var blockRow = mcuRow * component.v + row;
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var blockCol = mcuCol * component.h + col;
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var offset = getBlockBufferOffset(component, blockRow, blockCol);
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decode(component, offset);
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}
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function decodeBlock(component, decode, mcu) {
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var blockRow = (mcu / component.blocksPerLine) | 0;
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var blockCol = mcu % component.blocksPerLine;
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var offset = getBlockBufferOffset(component, blockRow, blockCol);
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decode(component, offset);
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}
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var componentsLength = components.length;
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var component, i, j, k, n;
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var decodeFn;
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if (progressive) {
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if (spectralStart === 0)
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decodeFn = successivePrev === 0 ? decodeDCFirst : decodeDCSuccessive;
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else
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decodeFn = successivePrev === 0 ? decodeACFirst : decodeACSuccessive;
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} else {
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decodeFn = decodeBaseline;
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}
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var mcu = 0, marker;
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var mcuExpected;
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if (componentsLength == 1) {
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mcuExpected = components[0].blocksPerLine * components[0].blocksPerColumn;
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} else {
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mcuExpected = mcusPerLine * frame.mcusPerColumn;
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}
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if (!resetInterval) {
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resetInterval = mcuExpected;
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}
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var h, v;
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while (mcu < mcuExpected) {
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// reset interval stuff
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for (i = 0; i < componentsLength; i++) {
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components[i].pred = 0;
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}
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eobrun = 0;
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if (componentsLength == 1) {
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component = components[0];
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for (n = 0; n < resetInterval; n++) {
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decodeBlock(component, decodeFn, mcu);
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mcu++;
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}
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} else {
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for (n = 0; n < resetInterval; n++) {
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for (i = 0; i < componentsLength; i++) {
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component = components[i];
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h = component.h;
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v = component.v;
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for (j = 0; j < v; j++) {
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for (k = 0; k < h; k++) {
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decodeMcu(component, decodeFn, mcu, j, k);
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}
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}
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}
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mcu++;
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}
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}
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// find marker
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bitsCount = 0;
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marker = (data[offset] << 8) | data[offset + 1];
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if (marker <= 0xFF00) {
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throw "marker was not found";
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}
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if (marker >= 0xFFD0 && marker <= 0xFFD7) { // RSTx
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offset += 2;
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} else {
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break;
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}
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}
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return offset - startOffset;
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}
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// A port of poppler's IDCT method which in turn is taken from:
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// Christoph Loeffler, Adriaan Ligtenberg, George S. Moschytz,
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// "Practical Fast 1-D DCT Algorithms with 11 Multiplications",
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// IEEE Intl. Conf. on Acoustics, Speech & Signal Processing, 1989,
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// 988-991.
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function quantizeAndInverse(component, blockBufferOffset, p) {
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var qt = component.quantizationTable;
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var v0, v1, v2, v3, v4, v5, v6, v7, t;
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var i;
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// dequant
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for (i = 0; i < 64; i++) {
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p[i] = component.blockData[blockBufferOffset + i] * qt[i];
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}
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// inverse DCT on rows
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for (i = 0; i < 8; ++i) {
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var row = 8 * i;
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// check for all-zero AC coefficients
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if (p[1 + row] == 0 && p[2 + row] == 0 && p[3 + row] == 0 &&
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p[4 + row] == 0 && p[5 + row] == 0 && p[6 + row] == 0 &&
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p[7 + row] == 0) {
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t = (dctSqrt2 * p[0 + row] + 512) >> 10;
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p[0 + row] = t;
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p[1 + row] = t;
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p[2 + row] = t;
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p[3 + row] = t;
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p[4 + row] = t;
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p[5 + row] = t;
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p[6 + row] = t;
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p[7 + row] = t;
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continue;
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}
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// stage 4
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v0 = (dctSqrt2 * p[0 + row] + 128) >> 8;
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v1 = (dctSqrt2 * p[4 + row] + 128) >> 8;
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v2 = p[2 + row];
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v3 = p[6 + row];
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v4 = (dctSqrt1d2 * (p[1 + row] - p[7 + row]) + 128) >> 8;
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v7 = (dctSqrt1d2 * (p[1 + row] + p[7 + row]) + 128) >> 8;
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v5 = p[3 + row] << 4;
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v6 = p[5 + row] << 4;
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// stage 3
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t = (v0 - v1+ 1) >> 1;
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v0 = (v0 + v1 + 1) >> 1;
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v1 = t;
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t = (v2 * dctSin6 + v3 * dctCos6 + 128) >> 8;
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v2 = (v2 * dctCos6 - v3 * dctSin6 + 128) >> 8;
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v3 = t;
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t = (v4 - v6 + 1) >> 1;
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v4 = (v4 + v6 + 1) >> 1;
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v6 = t;
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t = (v7 + v5 + 1) >> 1;
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v5 = (v7 - v5 + 1) >> 1;
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v7 = t;
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// stage 2
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t = (v0 - v3 + 1) >> 1;
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v0 = (v0 + v3 + 1) >> 1;
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v3 = t;
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t = (v1 - v2 + 1) >> 1;
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v1 = (v1 + v2 + 1) >> 1;
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v2 = t;
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t = (v4 * dctSin3 + v7 * dctCos3 + 2048) >> 12;
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v4 = (v4 * dctCos3 - v7 * dctSin3 + 2048) >> 12;
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v7 = t;
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t = (v5 * dctSin1 + v6 * dctCos1 + 2048) >> 12;
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v5 = (v5 * dctCos1 - v6 * dctSin1 + 2048) >> 12;
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v6 = t;
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// stage 1
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p[0 + row] = v0 + v7;
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p[7 + row] = v0 - v7;
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p[1 + row] = v1 + v6;
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p[6 + row] = v1 - v6;
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p[2 + row] = v2 + v5;
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p[5 + row] = v2 - v5;
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p[3 + row] = v3 + v4;
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p[4 + row] = v3 - v4;
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}
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// inverse DCT on columns
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for (i = 0; i < 8; ++i) {
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var col = i;
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// check for all-zero AC coefficients
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if (p[1*8 + col] == 0 && p[2*8 + col] == 0 && p[3*8 + col] == 0 &&
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p[4*8 + col] == 0 && p[5*8 + col] == 0 && p[6*8 + col] == 0 &&
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p[7*8 + col] == 0) {
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t = (dctSqrt2 * p[i+0] + 8192) >> 14;
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p[0*8 + col] = t;
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p[1*8 + col] = t;
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p[2*8 + col] = t;
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p[3*8 + col] = t;
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p[4*8 + col] = t;
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p[5*8 + col] = t;
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p[6*8 + col] = t;
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p[7*8 + col] = t;
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continue;
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}
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// stage 4
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v0 = (dctSqrt2 * p[0*8 + col] + 2048) >> 12;
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v1 = (dctSqrt2 * p[4*8 + col] + 2048) >> 12;
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v2 = p[2*8 + col];
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v3 = p[6*8 + col];
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v4 = (dctSqrt1d2 * (p[1*8 + col] - p[7*8 + col]) + 2048) >> 12;
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v7 = (dctSqrt1d2 * (p[1*8 + col] + p[7*8 + col]) + 2048) >> 12;
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v5 = p[3*8 + col];
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v6 = p[5*8 + col];
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// stage 3
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t = (v0 - v1 + 1) >> 1;
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v0 = (v0 + v1 + 1) >> 1;
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v1 = t;
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t = (v2 * dctSin6 + v3 * dctCos6 + 2048) >> 12;
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v2 = (v2 * dctCos6 - v3 * dctSin6 + 2048) >> 12;
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v3 = t;
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t = (v4 - v6 + 1) >> 1;
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v4 = (v4 + v6 + 1) >> 1;
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v6 = t;
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t = (v7 + v5 + 1) >> 1;
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v5 = (v7 - v5 + 1) >> 1;
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v7 = t;
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// stage 2
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t = (v0 - v3 + 1) >> 1;
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v0 = (v0 + v3 + 1) >> 1;
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v3 = t;
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t = (v1 - v2 + 1) >> 1;
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v1 = (v1 + v2 + 1) >> 1;
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v2 = t;
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t = (v4 * dctSin3 + v7 * dctCos3 + 2048) >> 12;
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v4 = (v4 * dctCos3 - v7 * dctSin3 + 2048) >> 12;
|
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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;
|
|
component.blockData[index] = clampTo8bitInt((p[i] + 2056) >> 4);
|
|
}
|
|
}
|
|
|
|
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 clampTo8bitInt(a) {
|
|
return a <= 0 ? 0 : a >= 255 ? 255 : a | 0;
|
|
}
|
|
|
|
function clamp0to255(a) {
|
|
return a <= 0 ? 0 : a >= 255 ? 255 : a;
|
|
}
|
|
|
|
constructor.prototype = {
|
|
load: function load(path) {
|
|
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 || xhr.mozResponseArrayBuffer);
|
|
this.parse(data);
|
|
if (this.onload)
|
|
this.onload();
|
|
}).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 = clamp0to255(Y + 1.402 * (Cr - 128));
|
|
G = clamp0to255(Y - 0.3441363 * (Cb - 128) - 0.71413636 * (Cr - 128));
|
|
B = clamp0to255(Y + 1.772 * (Cb - 128));
|
|
|
|
data[i ] = R;
|
|
data[i + 1] = G;
|
|
data[i + 2] = B;
|
|
}
|
|
}
|
|
break;
|
|
case 4:
|
|
// 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 = 255 - clamp0to255(Y + 1.402 * (Cr - 128));
|
|
M = 255 - clamp0to255(Y - 0.3441363 * (Cb - 128) - 0.71413636 * (Cr - 128));
|
|
Ye = 255 - clamp0to255(Y + 1.772 * (Cb - 128));
|
|
|
|
data[i ] = C;
|
|
data[i + 1] = M;
|
|
data[i + 2] = Ye;
|
|
// 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;
|
|
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++];
|
|
|
|
R = 255 - clamp0to255(C * (1 - K / 255) + K);
|
|
G = 255 - clamp0to255(M * (1 - K / 255) + K);
|
|
B = 255 - clamp0to255(Y * (1 - K / 255) + K);
|
|
|
|
imageDataArray[j++] = R;
|
|
imageDataArray[j++] = G;
|
|
imageDataArray[j++] = B;
|
|
imageDataArray[j++] = 255;
|
|
}
|
|
break;
|
|
default:
|
|
throw 'Unsupported color mode';
|
|
}
|
|
}
|
|
};
|
|
|
|
return constructor;
|
|
})();
|