897 lines
26 KiB
JavaScript
897 lines
26 KiB
JavaScript
import BaseDecoder from './basedecoder.js';
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/* -*- 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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const 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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const dctCos1 = 4017; // cos(pi/16)
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const dctSin1 = 799; // sin(pi/16)
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const dctCos3 = 3406; // cos(3*pi/16)
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const dctSin3 = 2276; // sin(3*pi/16)
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const dctCos6 = 1567; // cos(6*pi/16)
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const dctSin6 = 3784; // sin(6*pi/16)
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const dctSqrt2 = 5793; // sqrt(2)
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const dctSqrt1d2 = 2896;// sqrt(2) / 2
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function buildHuffmanTable(codeLengths, values) {
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let k = 0;
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const code = [];
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let length = 16;
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while (length > 0 && !codeLengths[length - 1]) {
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--length;
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}
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code.push({ children: [], index: 0 });
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let p = code[0];
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let q;
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for (let i = 0; i < length; i++) {
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for (let 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 decodeScan(data, initialOffset,
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frame, components, resetInterval,
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spectralStart, spectralEnd,
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successivePrev, successive) {
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const { mcusPerLine, progressive } = frame;
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const startOffset = initialOffset;
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let offset = initialOffset;
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let bitsData = 0;
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let 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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const nextByte = data[offset++];
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if (nextByte) {
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throw new Error(`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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let node = tree;
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let bit;
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while ((bit = readBit()) !== null) { // eslint-disable-line no-cond-assign
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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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}
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if (typeof node !== 'object') {
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throw new Error('invalid huffman sequence');
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}
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}
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return null;
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}
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function receive(initialLength) {
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let length = initialLength;
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let n = 0;
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while (length > 0) {
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const bit = readBit();
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if (bit === null) {
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return undefined;
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}
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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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const n = receive(length);
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if (n >= 1 << (length - 1)) {
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return n;
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}
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return n + (-1 << length) + 1;
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}
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function decodeBaseline(component, zz) {
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const t = decodeHuffman(component.huffmanTableDC);
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const diff = t === 0 ? 0 : receiveAndExtend(t);
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component.pred += diff;
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zz[0] = component.pred;
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let k = 1;
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while (k < 64) {
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const rs = decodeHuffman(component.huffmanTableAC);
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const s = rs & 15;
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const 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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}
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k += 16;
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} else {
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k += r;
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const z = dctZigZag[k];
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zz[z] = receiveAndExtend(s);
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k++;
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}
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}
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}
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function decodeDCFirst(component, zz) {
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const t = decodeHuffman(component.huffmanTableDC);
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const diff = t === 0 ? 0 : (receiveAndExtend(t) << successive);
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component.pred += diff;
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zz[0] = component.pred;
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}
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function decodeDCSuccessive(component, zz) {
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zz[0] |= readBit() << successive;
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}
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let eobrun = 0;
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function decodeACFirst(component, zz) {
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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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let k = spectralStart;
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const e = spectralEnd;
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while (k <= e) {
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const rs = decodeHuffman(component.huffmanTableAC);
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const s = rs & 15;
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const 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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} else {
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k += r;
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const z = dctZigZag[k];
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zz[z] = receiveAndExtend(s) * (1 << successive);
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k++;
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}
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}
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}
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let successiveACState = 0;
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let successiveACNextValue;
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function decodeACSuccessive(component, zz) {
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let k = spectralStart;
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const e = spectralEnd;
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let r = 0;
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while (k <= e) {
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const z = dctZigZag[k];
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const direction = zz[z] < 0 ? -1 : 1;
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switch (successiveACState) {
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case 0: { // initial state
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const rs = decodeHuffman(component.huffmanTableAC);
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const s = rs & 15;
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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 new Error('invalid ACn encoding');
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}
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successiveACNextValue = receiveAndExtend(s);
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successiveACState = r ? 2 : 3;
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}
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continue; // eslint-disable-line no-continue
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}
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case 1: // skipping r zero items
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case 2:
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if (zz[z]) {
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zz[z] += (readBit() << successive) * direction;
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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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}
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break;
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case 3: // set value for a zero item
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if (zz[z]) {
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zz[z] += (readBit() << successive) * direction;
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} else {
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zz[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 (zz[z]) {
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zz[z] += (readBit() << successive) * direction;
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}
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break;
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default:
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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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}
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function decodeMcu(component, decodeFunction, mcu, row, col) {
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const mcuRow = (mcu / mcusPerLine) | 0;
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const mcuCol = mcu % mcusPerLine;
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const blockRow = (mcuRow * component.v) + row;
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const blockCol = (mcuCol * component.h) + col;
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decodeFunction(component, component.blocks[blockRow][blockCol]);
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}
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function decodeBlock(component, decodeFunction, mcu) {
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const blockRow = (mcu / component.blocksPerLine) | 0;
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const blockCol = mcu % component.blocksPerLine;
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decodeFunction(component, component.blocks[blockRow][blockCol]);
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}
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const componentsLength = components.length;
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let component;
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let i;
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let j;
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let k;
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let n;
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let 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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}
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} else {
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decodeFn = decodeBaseline;
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}
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let mcu = 0;
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let marker;
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let 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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const usedResetInterval = resetInterval || mcuExpected;
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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 < usedResetInterval; 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 < usedResetInterval; n++) {
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for (i = 0; i < componentsLength; i++) {
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component = components[i];
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const { h, v } = component;
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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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// If we've reached our expected MCU's, stop decoding
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if (mcu === mcuExpected) {
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break;
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}
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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 new Error('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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function buildComponentData(frame, component) {
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const lines = [];
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const { blocksPerLine, blocksPerColumn } = component;
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const samplesPerLine = blocksPerLine << 3;
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const R = new Int32Array(64);
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const r = new Uint8Array(64);
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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(zz, dataOut, dataIn) {
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const qt = component.quantizationTable;
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let v0;
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let v1;
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let v2;
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let v3;
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let v4;
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let v5;
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let v6;
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let v7;
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let t;
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const p = dataIn;
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let i;
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// dequant
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for (i = 0; i < 64; i++) {
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p[i] = zz[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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const 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; // eslint-disable-line no-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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const 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 * dataIn[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; // eslint-disable-line no-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;
|
|
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) {
|
|
const sample = 128 + ((p[i] + 8) >> 4);
|
|
if (sample < 0) {
|
|
dataOut[i] = 0;
|
|
} else if (sample > 0XFF) {
|
|
dataOut[i] = 0xFF;
|
|
} else {
|
|
dataOut[i] = sample;
|
|
}
|
|
}
|
|
}
|
|
|
|
for (let blockRow = 0; blockRow < blocksPerColumn; blockRow++) {
|
|
const scanLine = blockRow << 3;
|
|
for (let i = 0; i < 8; i++) {
|
|
lines.push(new Uint8Array(samplesPerLine));
|
|
}
|
|
for (let blockCol = 0; blockCol < blocksPerLine; blockCol++) {
|
|
quantizeAndInverse(component.blocks[blockRow][blockCol], r, R);
|
|
|
|
let offset = 0;
|
|
const sample = blockCol << 3;
|
|
for (let j = 0; j < 8; j++) {
|
|
const line = lines[scanLine + j];
|
|
for (let i = 0; i < 8; i++) {
|
|
line[sample + i] = r[offset++];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return lines;
|
|
}
|
|
|
|
class JpegStreamReader {
|
|
constructor() {
|
|
this.jfif = null;
|
|
this.adobe = null;
|
|
|
|
this.quantizationTables = [];
|
|
this.huffmanTablesAC = [];
|
|
this.huffmanTablesDC = [];
|
|
this.resetFrames();
|
|
}
|
|
|
|
resetFrames() {
|
|
this.frames = [];
|
|
}
|
|
|
|
parse(data) {
|
|
let offset = 0;
|
|
// const { length } = data;
|
|
function readUint16() {
|
|
const value = (data[offset] << 8) | data[offset + 1];
|
|
offset += 2;
|
|
return value;
|
|
}
|
|
function readDataBlock() {
|
|
const length = readUint16();
|
|
const array = data.subarray(offset, offset + length - 2);
|
|
offset += array.length;
|
|
return array;
|
|
}
|
|
function prepareComponents(frame) {
|
|
let maxH = 0;
|
|
let maxV = 0;
|
|
let component;
|
|
let componentId;
|
|
for (componentId in frame.components) {
|
|
if (frame.components.hasOwnProperty(componentId)) {
|
|
component = frame.components[componentId];
|
|
if (maxH < component.h) {
|
|
maxH = component.h;
|
|
}
|
|
if (maxV < component.v) {
|
|
maxV = component.v;
|
|
}
|
|
}
|
|
}
|
|
const mcusPerLine = Math.ceil(frame.samplesPerLine / 8 / maxH);
|
|
const mcusPerColumn = Math.ceil(frame.scanLines / 8 / maxV);
|
|
for (componentId in frame.components) {
|
|
if (frame.components.hasOwnProperty(componentId)) {
|
|
component = frame.components[componentId];
|
|
const blocksPerLine = Math.ceil(Math.ceil(frame.samplesPerLine / 8) * component.h / maxH);
|
|
const blocksPerColumn = Math.ceil(Math.ceil(frame.scanLines / 8) * component.v / maxV);
|
|
const blocksPerLineForMcu = mcusPerLine * component.h;
|
|
const blocksPerColumnForMcu = mcusPerColumn * component.v;
|
|
const blocks = [];
|
|
for (let i = 0; i < blocksPerColumnForMcu; i++) {
|
|
const row = [];
|
|
for (let j = 0; j < blocksPerLineForMcu; j++) {
|
|
row.push(new Int32Array(64));
|
|
}
|
|
blocks.push(row);
|
|
}
|
|
component.blocksPerLine = blocksPerLine;
|
|
component.blocksPerColumn = blocksPerColumn;
|
|
component.blocks = blocks;
|
|
}
|
|
}
|
|
frame.maxH = maxH;
|
|
frame.maxV = maxV;
|
|
frame.mcusPerLine = mcusPerLine;
|
|
frame.mcusPerColumn = mcusPerColumn;
|
|
}
|
|
|
|
let fileMarker = readUint16();
|
|
if (fileMarker !== 0xFFD8) { // SOI (Start of Image)
|
|
throw new Error('SOI not found');
|
|
}
|
|
|
|
fileMarker = readUint16();
|
|
while (fileMarker !== 0xFFD9) { // EOI (End of image)
|
|
switch (fileMarker) {
|
|
case 0xFF00: break;
|
|
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)
|
|
const appData = readDataBlock();
|
|
|
|
if (fileMarker === 0xFFE0) {
|
|
if (appData[0] === 0x4A && appData[1] === 0x46 && appData[2] === 0x49
|
|
&& appData[3] === 0x46 && appData[4] === 0) { // 'JFIF\x00'
|
|
this.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'
|
|
this.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)
|
|
const quantizationTablesLength = readUint16();
|
|
const quantizationTablesEnd = quantizationTablesLength + offset - 2;
|
|
while (offset < quantizationTablesEnd) {
|
|
const quantizationTableSpec = data[offset++];
|
|
const tableData = new Int32Array(64);
|
|
if ((quantizationTableSpec >> 4) === 0) { // 8 bit values
|
|
for (let j = 0; j < 64; j++) {
|
|
const z = dctZigZag[j];
|
|
tableData[z] = data[offset++];
|
|
}
|
|
} else if ((quantizationTableSpec >> 4) === 1) { // 16 bit
|
|
for (let j = 0; j < 64; j++) {
|
|
const z = dctZigZag[j];
|
|
tableData[z] = readUint16();
|
|
}
|
|
} else {
|
|
throw new Error('DQT: invalid table spec');
|
|
}
|
|
this.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)
|
|
readUint16(); // skip data length
|
|
const frame = {
|
|
extended: (fileMarker === 0xFFC1),
|
|
progressive: (fileMarker === 0xFFC2),
|
|
precision: data[offset++],
|
|
scanLines: readUint16(),
|
|
samplesPerLine: readUint16(),
|
|
components: {},
|
|
componentsOrder: [],
|
|
};
|
|
|
|
const componentsCount = data[offset++];
|
|
let componentId;
|
|
// let maxH = 0;
|
|
// let maxV = 0;
|
|
for (let i = 0; i < componentsCount; i++) {
|
|
componentId = data[offset];
|
|
const h = data[offset + 1] >> 4;
|
|
const v = data[offset + 1] & 15;
|
|
const qId = data[offset + 2];
|
|
frame.componentsOrder.push(componentId);
|
|
frame.components[componentId] = {
|
|
h,
|
|
v,
|
|
quantizationIdx: qId,
|
|
};
|
|
offset += 3;
|
|
}
|
|
prepareComponents(frame);
|
|
this.frames.push(frame);
|
|
break;
|
|
}
|
|
|
|
case 0xFFC4: { // DHT (Define Huffman Tables)
|
|
const huffmanLength = readUint16();
|
|
for (let i = 2; i < huffmanLength;) {
|
|
const huffmanTableSpec = data[offset++];
|
|
const codeLengths = new Uint8Array(16);
|
|
let codeLengthSum = 0;
|
|
for (let j = 0; j < 16; j++, offset++) {
|
|
codeLengths[j] = data[offset];
|
|
codeLengthSum += codeLengths[j];
|
|
}
|
|
const huffmanValues = new Uint8Array(codeLengthSum);
|
|
for (let j = 0; j < codeLengthSum; j++, offset++) {
|
|
huffmanValues[j] = data[offset];
|
|
}
|
|
i += 17 + codeLengthSum;
|
|
|
|
if ((huffmanTableSpec >> 4) === 0) {
|
|
this.huffmanTablesDC[huffmanTableSpec & 15] = buildHuffmanTable(
|
|
codeLengths, huffmanValues,
|
|
);
|
|
} else {
|
|
this.huffmanTablesAC[huffmanTableSpec & 15] = buildHuffmanTable(
|
|
codeLengths, huffmanValues,
|
|
);
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
|
|
case 0xFFDD: // DRI (Define Restart Interval)
|
|
readUint16(); // skip data length
|
|
this.resetInterval = readUint16();
|
|
break;
|
|
|
|
case 0xFFDA: { // SOS (Start of Scan)
|
|
readUint16(); // skip length
|
|
const selectorsCount = data[offset++];
|
|
const components = [];
|
|
const frame = this.frames[0];
|
|
for (let i = 0; i < selectorsCount; i++) {
|
|
const component = frame.components[data[offset++]];
|
|
const tableSpec = data[offset++];
|
|
component.huffmanTableDC = this.huffmanTablesDC[tableSpec >> 4];
|
|
component.huffmanTableAC = this.huffmanTablesAC[tableSpec & 15];
|
|
components.push(component);
|
|
}
|
|
const spectralStart = data[offset++];
|
|
const spectralEnd = data[offset++];
|
|
const successiveApproximation = data[offset++];
|
|
const processed = decodeScan(data, offset,
|
|
frame, components, this.resetInterval,
|
|
spectralStart, spectralEnd,
|
|
successiveApproximation >> 4, successiveApproximation & 15);
|
|
offset += processed;
|
|
break;
|
|
}
|
|
|
|
case 0xFFFF: // Fill bytes
|
|
if (data[offset] !== 0xFF) { // Avoid skipping a valid marker.
|
|
offset--;
|
|
}
|
|
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 new Error(`unknown JPEG marker ${fileMarker.toString(16)}`);
|
|
}
|
|
fileMarker = readUint16();
|
|
}
|
|
}
|
|
|
|
getResult() {
|
|
const { frames } = this;
|
|
if (this.frames.length === 0) {
|
|
throw new Error('no frames were decoded');
|
|
} else if (this.frames.length > 1) {
|
|
console.warn('more than one frame is not supported');
|
|
}
|
|
|
|
// set each frame's components quantization table
|
|
for (let i = 0; i < this.frames.length; i++) {
|
|
const cp = this.frames[i].components;
|
|
for (const j of Object.keys(cp)) {
|
|
cp[j].quantizationTable = this.quantizationTables[cp[j].quantizationIdx];
|
|
delete cp[j].quantizationIdx;
|
|
}
|
|
}
|
|
|
|
const frame = frames[0];
|
|
const { components, componentsOrder } = frame;
|
|
const outComponents = [];
|
|
const width = frame.samplesPerLine;
|
|
const height = frame.scanLines;
|
|
|
|
for (let i = 0; i < componentsOrder.length; i++) {
|
|
const component = components[componentsOrder[i]];
|
|
outComponents.push({
|
|
lines: buildComponentData(frame, component),
|
|
scaleX: component.h / frame.maxH,
|
|
scaleY: component.v / frame.maxV,
|
|
});
|
|
}
|
|
|
|
const out = new Uint8Array(width * height * outComponents.length);
|
|
let oi = 0;
|
|
for (let y = 0; y < height; ++y) {
|
|
for (let x = 0; x < width; ++x) {
|
|
for (let i = 0; i < outComponents.length; ++i) {
|
|
const component = outComponents[i];
|
|
out[oi] = component.lines[0 | y * component.scaleY][0 | x * component.scaleX];
|
|
++oi;
|
|
}
|
|
}
|
|
}
|
|
return out;
|
|
}
|
|
}
|
|
|
|
export default class JpegDecoder extends BaseDecoder {
|
|
constructor(fileDirectory) {
|
|
super();
|
|
this.reader = new JpegStreamReader();
|
|
if (fileDirectory.JPEGTables) {
|
|
this.reader.parse(fileDirectory.JPEGTables);
|
|
}
|
|
}
|
|
|
|
decodeBlock(buffer) {
|
|
this.reader.resetFrames();
|
|
this.reader.parse(new Uint8Array(buffer));
|
|
return this.reader.getResult().buffer;
|
|
}
|
|
}
|