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560 lines
17 KiB
560 lines
17 KiB
/*
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* MIT LICENSE
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* Copyright (c) 2011 Devon Govett
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of this
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* software and associated documentation files (the "Software"), to deal in the Software
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* without restriction, including without limitation the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
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* to whom the Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all copies or
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* substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
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* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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window.PNG = (function() {
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let APNG_DISPOSE_OP_NONE = 0;
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let APNG_DISPOSE_OP_BACKGROUND = 1;
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let APNG_DISPOSE_OP_PREVIOUS = 2;
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let APNG_BLEND_OP_SOURCE = 0;
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let APNG_BLEND_OP_OVER = 1;
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let scratchCanvas = document.createElement('canvas');
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let scratchCtx = scratchCanvas.getContext('2d');
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let makeImage = function(imageData) {
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scratchCtx.width = imageData.width;
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scratchCtx.height = imageData.height;
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scratchCtx.clearRect(0, 0, imageData.width, imageData.height);
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scratchCtx.putImageData(imageData, 0, 0);
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const img = new Image();
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img.src = scratchCanvas.toDataURL();
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return img;
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};
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class PNG {
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static load(url, canvas, callback) {
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if (typeof canvas === 'function') {
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callback = canvas;
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}
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const xhr = new XMLHttpRequest();
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xhr.open('GET', url, true);
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xhr.responseType = 'arraybuffer';
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xhr.onload = () => {
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const data = new Uint8Array(xhr.response || xhr.mozResponseArrayBuffer);
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const png = new PNG(data);
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if (typeof (canvas && canvas.getContext) === 'function') {
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png.render(canvas);
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}
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return typeof callback === 'function' ? callback(png) : undefined;
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};
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return xhr.send(null);
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}
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constructor(data1) {
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let i;
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this.data = data1;
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this.pos = 8; // Skip the default header
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this.palette = [];
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this.imgData = [];
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this.transparency = {};
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this.animation = null;
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this.text = {};
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let frame = null;
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while (true) {
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var data;
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let chunkSize = this.readUInt32();
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let section = '';
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for (i = 0; i < 4; i++) {
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section += String.fromCharCode(this.data[this.pos++]);
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}
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switch (section) {
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case 'IHDR':
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// we can grab interesting values from here (like width, height, etc)
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this.width = this.readUInt32();
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this.height = this.readUInt32();
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this.bits = this.data[this.pos++];
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this.colorType = this.data[this.pos++];
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this.compressionMethod = this.data[this.pos++];
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this.filterMethod = this.data[this.pos++];
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this.interlaceMethod = this.data[this.pos++];
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break;
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case 'acTL':
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// we have an animated PNG
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this.animation = {
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numFrames: this.readUInt32(),
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numPlays: this.readUInt32() || Infinity,
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frames: []
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};
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break;
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case 'PLTE':
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this.palette = this.read(chunkSize);
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break;
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case 'fcTL':
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if (frame) {
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this.animation.frames.push(frame);
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}
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this.pos += 4; // skip sequence number
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frame = {
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width: this.readUInt32(),
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height: this.readUInt32(),
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xOffset: this.readUInt32(),
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yOffset: this.readUInt32()
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};
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var delayNum = this.readUInt16();
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var delayDen = this.readUInt16() || 100;
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frame.delay = (1000 * delayNum) / delayDen;
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frame.disposeOp = this.data[this.pos++];
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frame.blendOp = this.data[this.pos++];
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frame.data = [];
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break;
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case 'IDAT':
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case 'fdAT':
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if (section === 'fdAT') {
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this.pos += 4; // skip sequence number
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chunkSize -= 4;
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}
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data = (frame && frame.data) || this.imgData;
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for (i = 0; i < chunkSize; i++) {
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data.push(this.data[this.pos++]);
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}
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break;
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case 'tRNS':
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// This chunk can only occur once and it must occur after the
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// PLTE chunk and before the IDAT chunk.
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this.transparency = {};
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switch (this.colorType) {
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case 3:
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// Indexed color, RGB. Each byte in this chunk is an alpha for
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// the palette index in the PLTE ("palette") chunk up until the
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// last non-opaque entry. Set up an array, stretching over all
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// palette entries which will be 0 (opaque) or 1 (transparent).
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this.transparency.indexed = this.read(chunkSize);
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var short = 255 - this.transparency.indexed.length;
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if (short > 0) {
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for (i = 0; i < short; i++) {
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this.transparency.indexed.push(255);
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}
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}
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break;
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case 0:
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// Greyscale. Corresponding to entries in the PLTE chunk.
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// Grey is two bytes, range 0 .. (2 ^ bit-depth) - 1
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this.transparency.grayscale = this.read(chunkSize)[0];
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break;
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case 2:
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// True color with proper alpha channel.
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this.transparency.rgb = this.read(chunkSize);
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break;
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}
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break;
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case 'tEXt':
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var text = this.read(chunkSize);
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var index = text.indexOf(0);
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var key = String.fromCharCode.apply(String, text.slice(0, index));
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this.text[key] = String.fromCharCode.apply(
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String,
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text.slice(index + 1)
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);
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break;
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case 'IEND':
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if (frame) {
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this.animation.frames.push(frame);
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}
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// we've got everything we need!
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switch (this.colorType) {
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case 0:
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case 3:
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case 4:
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this.colors = 1;
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break;
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case 2:
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case 6:
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this.colors = 3;
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break;
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}
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this.hasAlphaChannel = [4, 6].includes(this.colorType);
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var colors = this.colors + (this.hasAlphaChannel ? 1 : 0);
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this.pixelBitlength = this.bits * colors;
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switch (this.colors) {
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case 1:
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this.colorSpace = 'DeviceGray';
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break;
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case 3:
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this.colorSpace = 'DeviceRGB';
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break;
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}
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this.imgData = new Uint8Array(this.imgData);
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return;
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break;
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default:
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// unknown (or unimportant) section, skip it
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this.pos += chunkSize;
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}
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this.pos += 4; // Skip the CRC
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if (this.pos > this.data.length) {
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throw new Error('Incomplete or corrupt PNG file');
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}
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}
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}
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read(bytes) {
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const result = new Array(bytes);
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for (let i = 0; i < bytes; i++) {
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result[i] = this.data[this.pos++];
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}
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return result;
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}
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readUInt32() {
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const b1 = this.data[this.pos++] << 24;
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const b2 = this.data[this.pos++] << 16;
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const b3 = this.data[this.pos++] << 8;
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const b4 = this.data[this.pos++];
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return b1 | b2 | b3 | b4;
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}
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readUInt16() {
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const b1 = this.data[this.pos++] << 8;
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const b2 = this.data[this.pos++];
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return b1 | b2;
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}
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decodePixels(data) {
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if (data == null) {
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data = this.imgData;
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}
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if (data.length === 0) {
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return new Uint8Array(0);
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}
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data = new FlateStream(data);
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data = data.getBytes();
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const { width, height } = this;
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const pixelBytes = this.pixelBitlength / 8;
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const pixels = new Uint8Array(width * height * pixelBytes);
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const { length } = data;
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let pos = 0;
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function pass(x0, y0, dx, dy, singlePass = false) {
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const w = Math.ceil((width - x0) / dx);
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const h = Math.ceil((height - y0) / dy);
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const scanlineLength = pixelBytes * w;
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const buffer = singlePass ? pixels : new Uint8Array(scanlineLength * h);
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let row = 0;
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let c = 0;
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while (row < h && pos < length) {
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var byte, col, i, left, upper;
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switch (data[pos++]) {
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case 0: // None
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for (i = 0; i < scanlineLength; i++) {
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buffer[c++] = data[pos++];
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}
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break;
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case 1: // Sub
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for (i = 0; i < scanlineLength; i++) {
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byte = data[pos++];
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left = i < pixelBytes ? 0 : buffer[c - pixelBytes];
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buffer[c++] = (byte + left) % 256;
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}
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break;
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case 2: // Up
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for (i = 0; i < scanlineLength; i++) {
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byte = data[pos++];
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col = (i - (i % pixelBytes)) / pixelBytes;
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upper =
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row &&
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buffer[
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(row - 1) * scanlineLength +
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col * pixelBytes +
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(i % pixelBytes)
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];
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buffer[c++] = (upper + byte) % 256;
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}
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break;
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case 3: // Average
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for (i = 0; i < scanlineLength; i++) {
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byte = data[pos++];
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col = (i - (i % pixelBytes)) / pixelBytes;
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left = i < pixelBytes ? 0 : buffer[c - pixelBytes];
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upper =
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row &&
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buffer[
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(row - 1) * scanlineLength +
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col * pixelBytes +
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(i % pixelBytes)
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];
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buffer[c++] = (byte + Math.floor((left + upper) / 2)) % 256;
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}
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break;
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case 4: // Paeth
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for (i = 0; i < scanlineLength; i++) {
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var paeth, upperLeft;
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byte = data[pos++];
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col = (i - (i % pixelBytes)) / pixelBytes;
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left = i < pixelBytes ? 0 : buffer[c - pixelBytes];
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if (row === 0) {
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upper = upperLeft = 0;
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} else {
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upper =
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buffer[
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(row - 1) * scanlineLength +
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col * pixelBytes +
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(i % pixelBytes)
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];
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upperLeft =
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col &&
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buffer[
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(row - 1) * scanlineLength +
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(col - 1) * pixelBytes +
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(i % pixelBytes)
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];
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}
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const p = left + upper - upperLeft;
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const pa = Math.abs(p - left);
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const pb = Math.abs(p - upper);
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const pc = Math.abs(p - upperLeft);
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if (pa <= pb && pa <= pc) {
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paeth = left;
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} else if (pb <= pc) {
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paeth = upper;
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} else {
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paeth = upperLeft;
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}
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buffer[c++] = (byte + paeth) % 256;
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}
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break;
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default:
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throw new Error(`Invalid filter algorithm: ${data[pos - 1]}`);
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}
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if (!singlePass) {
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let pixelsPos = ((y0 + row * dy) * width + x0) * pixelBytes;
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let bufferPos = row * scanlineLength;
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for (i = 0; i < w; i++) {
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for (let j = 0; j < pixelBytes; j++)
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pixels[pixelsPos++] = buffer[bufferPos++];
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pixelsPos += (dx - 1) * pixelBytes;
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}
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}
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row++;
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}
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}
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if (this.interlaceMethod === 1) {
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/*
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1 6 4 6 2 6 4 6
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7 7 7 7 7 7 7 7
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5 6 5 6 5 6 5 6
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7 7 7 7 7 7 7 7
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3 6 4 6 3 6 4 6
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7 7 7 7 7 7 7 7
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5 6 5 6 5 6 5 6
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7 7 7 7 7 7 7 7
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*/
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pass(0, 0, 8, 8); // 1
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pass(4, 0, 8, 8); // 2
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pass(0, 4, 4, 8); // 3
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pass(2, 0, 4, 4); // 4
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pass(0, 2, 2, 4); // 5
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pass(1, 0, 2, 2); // 6
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pass(0, 1, 1, 2); // 7
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} else {
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pass(0, 0, 1, 1, true);
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}
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return pixels;
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}
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decodePalette() {
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const { palette } = this;
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const { length } = palette;
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const transparency = this.transparency.indexed || [];
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const ret = new Uint8Array((transparency.length || 0) + length);
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let pos = 0;
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let c = 0;
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for (let i = 0; i < length; i += 3) {
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var left;
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ret[pos++] = palette[i];
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ret[pos++] = palette[i + 1];
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ret[pos++] = palette[i + 2];
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ret[pos++] = (left = transparency[c++]) != null ? left : 255;
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}
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return ret;
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}
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copyToImageData(imageData, pixels) {
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let j, k;
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let { colors } = this;
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let palette = null;
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let alpha = this.hasAlphaChannel;
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if (this.palette.length) {
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palette =
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this._decodedPalette || (this._decodedPalette = this.decodePalette());
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colors = 4;
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alpha = true;
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}
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const data = imageData.data || imageData;
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const { length } = data;
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const input = palette || pixels;
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let i = (j = 0);
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if (colors === 1) {
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while (i < length) {
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k = palette ? pixels[i / 4] * 4 : j;
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const v = input[k++];
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data[i++] = v;
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data[i++] = v;
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data[i++] = v;
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data[i++] = alpha ? input[k++] : 255;
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j = k;
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}
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} else {
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while (i < length) {
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k = palette ? pixels[i / 4] * 4 : j;
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data[i++] = input[k++];
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data[i++] = input[k++];
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data[i++] = input[k++];
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data[i++] = alpha ? input[k++] : 255;
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j = k;
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}
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}
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}
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decode() {
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const ret = new Uint8Array(this.width * this.height * 4);
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this.copyToImageData(ret, this.decodePixels());
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return ret;
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}
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decodeFrames(ctx) {
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if (!this.animation) {
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return;
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}
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for (let i = 0; i < this.animation.frames.length; i++) {
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const frame = this.animation.frames[i];
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const imageData = ctx.createImageData(frame.width, frame.height);
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const pixels = this.decodePixels(new Uint8Array(frame.data));
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this.copyToImageData(imageData, pixels);
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frame.imageData = imageData;
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frame.image = makeImage(imageData);
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}
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}
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renderFrame(ctx, number) {
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const { frames } = this.animation;
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const frame = frames[number];
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const prev = frames[number - 1];
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// if we're on the first frame, clear the canvas
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if (number === 0) {
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ctx.clearRect(0, 0, this.width, this.height);
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}
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// check the previous frame's dispose operation
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if ((prev && prev.disposeOp) === APNG_DISPOSE_OP_BACKGROUND) {
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ctx.clearRect(prev.xOffset, prev.yOffset, prev.width, prev.height);
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} else if ((prev && prev.disposeOp) === APNG_DISPOSE_OP_PREVIOUS) {
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ctx.putImageData(prev.imageData, prev.xOffset, prev.yOffset);
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}
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// APNG_BLEND_OP_SOURCE overwrites the previous data
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if (frame.blendOp === APNG_BLEND_OP_SOURCE) {
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ctx.clearRect(frame.xOffset, frame.yOffset, frame.width, frame.height);
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}
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// draw the current frame
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return ctx.drawImage(frame.image, frame.xOffset, frame.yOffset);
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}
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animate(ctx) {
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let frameNumber = 0;
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const { numFrames, frames, numPlays } = this.animation;
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const doFrame = () => {
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const f = frameNumber++ % numFrames;
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const frame = frames[f];
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this.renderFrame(ctx, f);
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if (numFrames > 1 && frameNumber / numFrames < numPlays) {
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this.animation._timeout = setTimeout(doFrame, frame.delay);
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}
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};
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doFrame();
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}
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stopAnimation() {
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return clearTimeout(this.animation && this.animation._timeout);
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}
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render(canvas) {
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// if this canvas was displaying another image before,
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// stop the animation on it
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if (canvas._png) {
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canvas._png.stopAnimation();
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}
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canvas._png = this;
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canvas.width = this.width;
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canvas.height = this.height;
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const ctx = canvas.getContext('2d');
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if (this.animation) {
|
|
this.decodeFrames(ctx);
|
|
return this.animate(ctx);
|
|
} else {
|
|
const data = ctx.createImageData(this.width, this.height);
|
|
this.copyToImageData(data, this.decodePixels());
|
|
return ctx.putImageData(data, 0, 0);
|
|
}
|
|
}
|
|
}
|
|
return PNG;
|
|
})();
|