mirror of
https://github.com/kkapsner/CanvasBlocker
synced 2024-11-01 02:48:44 +01:00
472 lines
14 KiB
JavaScript
472 lines
14 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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(function(){
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"use strict";
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const scope = ((typeof exports) !== "undefined")? exports: require.register("./modifiedCanvasAPI");
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const colorStatistics = require("./colorStatistics");
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const logging = require("./logging");
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const extension = require("./extension");
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const webgl = require("./webgl");
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const {checkerWrapper} = require("./modifiedAPIFunctions");
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let randomSupply = null;
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function getContext(window, canvas){
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return window.HTMLCanvasElement.prototype.getContext.call(canvas, "2d") ||
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window.HTMLCanvasElement.prototype.getContext.call(canvas, "webgl") ||
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window.HTMLCanvasElement.prototype.getContext.call(canvas, "experimental-webgl") ||
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window.HTMLCanvasElement.prototype.getContext.call(canvas, "webgl2") ||
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window.HTMLCanvasElement.prototype.getContext.call(canvas, "experimental-webgl2");
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}
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function getImageData(window, context){
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let imageData;
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let source;
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if ((context.canvas.width || 0) * (context.canvas.height || 0) === 0){
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imageData = new (extension.getWrapped(window).ImageData)(0, 0);
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source = new (extension.getWrapped(window).ImageData)(0, 0);
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}
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else if (context instanceof window.CanvasRenderingContext2D){
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imageData = window.CanvasRenderingContext2D.prototype.getImageData.call(
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context,
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0, 0,
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context.canvas.width, context.canvas.height
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);
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source = imageData.data;
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}
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else {
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imageData = new (extension.getWrapped(window).ImageData)(context.canvas.width, context.canvas.height);
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source = new Uint8Array(imageData.data.length);
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(
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context instanceof window.WebGLRenderingContext?
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window.WebGLRenderingContext:
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window.WebGL2RenderingContext
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).prototype.readPixels.call(
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context,
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0, 0, context.canvas.width, context.canvas.height,
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context.RGBA, context.UNSIGNED_BYTE,
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source
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);
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}
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return {
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imageData,
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source
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};
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}
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const canvasCache = Object.create(null);
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function getFakeCanvas(window, original, prefs){
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try {
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let originalDataURL;
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if (prefs("useCanvasCache")){
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originalDataURL = original.toDataURL();
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const cached = canvasCache[originalDataURL];
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if (cached){
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return cached;
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}
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}
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// original may not be a canvas -> we must not leak an error
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let context = getContext(window, original);
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const {imageData, source} = getImageData(window, context);
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const desc = imageData.data;
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const l = desc.length;
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let ignoredColors = {};
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let statistic;
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if (prefs("ignoreFrequentColors")){
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statistic = colorStatistics.compute(source);
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ignoredColors = statistic.getMaxColors(prefs("ignoreFrequentColors"));
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}
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if (prefs("minColors")){
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if (!colorStatistics.hasMoreColors(source, prefs("minColors"), statistic)){
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return original;
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}
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}
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const rng = randomSupply.getPixelRng(l, window, ignoredColors);
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const fakeAlphaChannel = prefs("fakeAlphaChannel");
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for (let i = 0; i < l; i += 4){
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const [r, g, b, a] = rng(
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source[i + 0],
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source[i + 1],
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source[i + 2],
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source[i + 3],
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i / 4
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);
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desc[i + 0] = r;
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desc[i + 1] = g;
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desc[i + 2] = b;
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desc[i + 3] = fakeAlphaChannel? a: source[i + 3];
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}
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const canvas = original.cloneNode(true);
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context = window.HTMLCanvasElement.prototype.getContext.call(canvas, "2d");
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context.putImageData(imageData, 0, 0);
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if (prefs("useCanvasCache")){
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canvasCache[originalDataURL] = canvas;
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canvasCache[canvas.toDataURL()] = canvas;
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}
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return canvas;
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}
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catch (error){
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logging.warning("Error while faking:", error);
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return original;
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}
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}
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function randomMixImageData(window, imageData1, imageData2){
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const data1 = imageData1.data;
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const data2 = imageData2.data;
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const l = data1.length;
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if (l === data2.length){
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const rng = randomSupply.getPixelRng(l, window, {});
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for (let i = 0; i < l; i += 4){
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const signR = data1[i + 0] > data2[i + 0]? -1: 1;
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const signG = data1[i + 1] > data2[i + 1]? -1: 1;
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const signB = data1[i + 2] > data2[i + 2]? -1: 1;
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const signA = data1[i + 3] > data2[i + 3]? -1: 1;
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const [deltaR, deltaG, deltaB, deltaA] = rng(
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signR * (data2[i + 0] - data1[i + 0]),
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signG * (data2[i + 1] - data1[i + 1]),
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signB * (data2[i + 2] - data1[i + 2]),
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signA * (data2[i + 3] - data1[i + 3]),
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i / 4
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);
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data2[i + 0] = data1[i + 0] + signR * deltaR;
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data2[i + 1] = data1[i + 1] + signG * deltaG;
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data2[i + 2] = data1[i + 2] + signB * deltaB;
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data2[i + 3] = data1[i + 3] + signA * deltaA;
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}
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}
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return imageData2;
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}
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function canvasSizeShouldBeFaked(canvas, prefs){
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if (canvas){
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const size = canvas.height * canvas.width;
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const maxSize = prefs("maxFakeSize") || Number.POSITIVE_INFINITY;
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const minSize = prefs("minFakeSize") || 0;
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return size > minSize && size <= maxSize;
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}
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else {
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return true;
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}
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}
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function getProtectedPartChecker(pref, url){
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const protectedPart = pref("protectedCanvasPart", url);
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if (protectedPart === "everything"){
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return function(){
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return true;
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};
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}
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else if (protectedPart === "nothing"){
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return function(){
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return false;
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};
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}
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else {
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return function(parts){
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if (Array.isArray(parts)){
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return parts.some(function(part){
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return part === protectedPart;
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});
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}
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else {
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return parts === protectedPart;
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}
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};
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}
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}
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scope.setRandomSupply = function(supply){
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randomSupply = supply;
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webgl.setRandomSupply(supply);
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};
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const canvasContextType = new WeakMap();
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function createGetStatus(protectedPart){
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if (protectedPart === "readout+"){
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return function(obj, status, prefs){
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const protectedPartChecker = getProtectedPartChecker(prefs, status.url);
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status = Object.create(status);
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status.active = protectedPartChecker("readout");
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if (!status.active && protectedPartChecker("input")){
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const contextType = canvasContextType.get(obj);
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status.active = contextType !== "2d";
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}
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return status;
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};
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}
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return function getStatus(obj, status, prefs){
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const protectedPartChecker = getProtectedPartChecker(prefs, status.url);
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status = Object.create(status);
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status.active = protectedPartChecker(protectedPart);
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return status;
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};
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}
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function useFakeCanvasCallback(args, check){
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const {prefs, notify, window, original} = check;
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if (canvasSizeShouldBeFaked(this, prefs)){
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const fakeCanvas = getFakeCanvas(window, this, prefs);
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if (fakeCanvas !== this){
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notify("fakedReadout");
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}
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return original.call(fakeCanvas, ...args);
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}
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else {
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return original.call(this, ...args);
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}
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}
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function mixOnInputCallback(args, check){
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const {prefs, notify, window, original} = check;
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if (!this || canvasSizeShouldBeFaked(this.canvas, prefs)){
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notify("fakedInput");
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let oldImageData;
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try {
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// "this" is not trustable - it may be not a context
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oldImageData = getImageData(window, this).imageData;
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}
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catch (error){
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// nothing to do here
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}
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// if "this" is not a correct context the next line will throw an error
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const ret = original.call(this, ...args);
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const newImageData = getImageData(window, this).imageData;
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this.putImageData(randomMixImageData(window, oldImageData, newImageData), 0, 0);
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return ret;
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}
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else {
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return original.call(this, ...args);
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}
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}
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// changed functions and their fakes
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scope.changedFunctions = {
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getContext: {
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type: "context",
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getStatus: function(obj, status, prefs){
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if (status.internal){
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return {
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mode: "allow",
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type: status.type,
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active: false
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};
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}
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else if (getProtectedPartChecker(prefs, status.url)("input")){
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return {
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mode: status.mode,
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type: status.type,
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active: true
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};
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}
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else {
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status = Object.create(status);
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status.active = false;
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return status;
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}
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},
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object: "HTMLCanvasElement",
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fakeGenerator: function(checker){
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return function(context, contextAttributes){
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return checkerWrapper(checker, this, arguments, function(args, check){
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const {original} = check;
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canvasContextType.set(this, context);
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return original.call(this, ...args);
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});
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};
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}
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},
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toDataURL: {
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type: "readout",
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getStatus: createGetStatus("readout+"),
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object: "HTMLCanvasElement",
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fakeGenerator: function(checker){
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return function toDataURL(){
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return checkerWrapper(checker, this, arguments, useFakeCanvasCallback);
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};
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}
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},
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toBlob: {
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type: "readout",
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getStatus: createGetStatus("readout+"),
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object: "HTMLCanvasElement",
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fakeGenerator: function(checker){
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return function toBlob(callback){
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return checkerWrapper(checker, this, arguments, useFakeCanvasCallback);
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};
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},
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exportOptions: {allowCallbacks: true}
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},
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mozGetAsFile: {
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type: "readout",
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getStatus: createGetStatus("readout+"),
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object: "HTMLCanvasElement",
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fakeGenerator: function(checker){
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return function mozGetAsFile(callback){
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return checkerWrapper(checker, this, arguments, useFakeCanvasCallback);
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};
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}
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},
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getImageData: {
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type: "readout",
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getStatus: createGetStatus("readout"),
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object: "CanvasRenderingContext2D",
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fakeGenerator: function(checker){
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return function getImageData(sx, sy, sw, sh){
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return checkerWrapper(checker, this, arguments, function(args, check){
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const {prefs, notify, window, original} = check;
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if (!this || canvasSizeShouldBeFaked(this.canvas, prefs)){
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let fakeCanvas;
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let context = this;
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if (this && this.canvas) {
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fakeCanvas = getFakeCanvas(window, this.canvas, prefs);
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}
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if (fakeCanvas && fakeCanvas !== this.canvas){
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notify("fakedReadout");
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context = window.HTMLCanvasElement.prototype.getContext.call(
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fakeCanvas,
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"2d"
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);
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}
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return original.call(context, ...args);
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}
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else {
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return original.call(this, ...args);
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}
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});
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};
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}
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},
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isPointInPath: {
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type: "readout",
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getStatus: createGetStatus("readout"),
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object: "CanvasRenderingContext2D",
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fakeGenerator: function(checker){
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return function isPointInPath(x, y){
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return checkerWrapper(checker, this, arguments, function(args, check){
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const {notify, window, original} = check;
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const rng = randomSupply.getValueRng(1, window);
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const originalValue = original.call(this, ...args);
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if ((typeof originalValue) === "boolean"){
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notify("fakedReadout");
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const index = x + this.width * y;
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return original.call(this, rng(x, index), rng(y, index), args[2]);
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}
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else {
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return originalValue;
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}
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});
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};
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}
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},
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isPointInStroke: {
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type: "readout",
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getStatus: createGetStatus("readout"),
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object: "CanvasRenderingContext2D",
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fakeGenerator: function(checker){
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return function isPointInStroke(x, y){
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return checkerWrapper(checker, this, arguments, function(args, check){
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const {notify, window, original} = check;
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const rng = randomSupply.getValueRng(1, window);
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const originalValue = original.call(this, ...args);
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if ((typeof originalValue) === "boolean"){
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notify("fakedReadout");
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if (x instanceof window.Path2D){
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let path = x;
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x = y;
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y = args[2];
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let index = x + this.width * y;
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return original.call(this, path, rng(x, index), rng(y, index));
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}
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else {
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let index = x + this.width * y;
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return original.call(this, rng(x, index), rng(y, index));
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}
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}
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else {
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return originalValue;
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}
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});
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};
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}
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},
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fillText: {
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type: "input",
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getStatus: createGetStatus("input"),
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object: "CanvasRenderingContext2D",
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fakeGenerator: function(checker){
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return function fillText(str, x, y){
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return checkerWrapper(checker, this, arguments, mixOnInputCallback);
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};
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}
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},
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strokeText: {
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type: "input",
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getStatus: createGetStatus("input"),
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object: "CanvasRenderingContext2D",
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fakeGenerator: function(checker){
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return function strokeText(str, x, y){
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return checkerWrapper(checker, this, arguments, mixOnInputCallback);
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};
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}
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},
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readPixels: {
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type: "readout",
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getStatus: createGetStatus(["readout", "input"]),
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object: ["WebGLRenderingContext", "WebGL2RenderingContext"],
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fakeGenerator: function(checker){
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// eslint-disable-next-line max-params
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return function readPixels(x, y, width, height, format, type, pixels){
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return checkerWrapper(checker, this, arguments, function(args, check){
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const {prefs, notify, window, original} = check;
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if (!this || canvasSizeShouldBeFaked(this.canvas, prefs)){
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notify("fakedReadout");
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const fakeCanvas = getFakeCanvas(window, this.canvas, prefs);
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const {context} = webgl.copyCanvasToWebgl(
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window,
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fakeCanvas,
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this instanceof window.WebGLRenderingContext? "webgl": "webgl2"
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);
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return original.call(context, ...args);
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}
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else {
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return original.call(this, ...args);
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}
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});
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};
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}
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},
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getParameter: {
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type: "readout",
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getStatus: createGetStatus(["readout", "input"]),
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object: ["WebGLRenderingContext", "WebGL2RenderingContext"],
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fakeGenerator: function(checker){
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webgl.initializeParameterDefinitions();
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return function getParameter(pname){
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return checkerWrapper(checker, this, arguments, function(args, check){
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const {prefs, notify, window, original} = check;
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const originalValue = original.call(this, ...args);
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if (webgl.parameterChangeDefinition[pname]){
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const definition = webgl.parameterChangeDefinition[pname];
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const {value, faked} = definition.fake(originalValue, window, prefs);
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if (faked){
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notify("fakedReadout");
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}
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return value;
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}
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else {
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return originalValue;
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}
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});
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};
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}
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}
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};
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Object.keys(scope.changedFunctions).forEach(function(key){
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scope.changedFunctions[key].api = "canvas";
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});
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}()); |