From 2e91f85d8f3d32b45eaa4a9b9e5e9fcdc806420e Mon Sep 17 00:00:00 2001
From: kkapsner <github@mail.kkapsner.de>
Date: Mon, 1 Jun 2020 14:25:47 +0200
Subject: [PATCH] Added offscreen canvas protection

Fixes #467
---
 lib/intercept.js          |  6 +++++
 lib/modifiedCanvasAPI.js  | 51 ++++++++++++++++++++++++++++++++++++++-
 lib/settingDefinitions.js |  4 ++-
 releaseNotes.txt          |  1 +
 4 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/lib/intercept.js b/lib/intercept.js
index 024b13f..cd5ce96 100644
--- a/lib/intercept.js
+++ b/lib/intercept.js
@@ -84,6 +84,9 @@
 	const forEachFunction = function(windowToProcess, callback){
 		apiNames.forEach(function(name){
 			const changedFunction = changedFunctions[name];
+			if (changedFunction.name){
+				name = changedFunction.name;
+			}
 			getAllFunctionObjects(windowToProcess, changedFunction).forEach(function(object){
 				if (object){
 					callback({name, object: object, changedFunction});
@@ -317,6 +320,9 @@
 	function interceptFunctions(windowToProcess, siteStatus, {checkStack, ask, notify, prefs}){
 		apiNames.forEach(function(name){
 			const changedFunction = changedFunctions[name];
+			if (changedFunction.name){
+				name = changedFunction.name;
+			}
 			const functionStatus = changedFunction.getStatus(undefined, siteStatus, prefs);
 			logging.verbose("status for", name, ":", functionStatus);
 			if (!functionStatus.active) return;
diff --git a/lib/modifiedCanvasAPI.js b/lib/modifiedCanvasAPI.js
index d1c1169..b05bbf1 100644
--- a/lib/modifiedCanvasAPI.js
+++ b/lib/modifiedCanvasAPI.js
@@ -244,6 +244,34 @@
 		}
 	}
 	
+	function offscreenToBlobCallback(args, check){
+		const {prefs, notify, window, original} = check;
+		if (canvasSizeShouldBeFaked(this, prefs)){
+			try {
+				const options = args[0];
+				const canvas = window.document.createElement("canvas");
+				canvas.width = this.width;
+				canvas.height = this.height;
+				const context = canvas.getContext("2d");
+				context.drawImage(this.transferToImageBitmap(), 0, 0);
+				const fakeCanvas = getFakeCanvas(window, canvas, prefs);
+				if (fakeCanvas !== canvas){
+					notify("fakedReadout");
+				}
+				return new window.Promise(function(resolve){
+					fakeCanvas.toBlob(resolve, options && options.type, options && options.quality);
+				});
+			}
+			catch (error){
+				logging.warning("Error while faking:", error);
+				return original.call(this, ...args);
+			}
+		}
+		else {
+			return original.call(this, ...args);
+		}
+	}
+	
 	const isPointCache = Object.create(null);
 	function getIsPointCacheIndex(x, y, values){
 		return String.fromCodePoint(...values, x, y);
@@ -496,7 +524,28 @@
 					});
 				};
 			}
-		}
+		},
+		convertToBlob: {
+			type: "readout",
+			getStatus: createGetStatus("readout"),
+			object: ["OffscreenCanvas"],
+			fakeGenerator: function(checker){
+				return function convertToBlob(){
+					return checkerWrapper(checker, this, arguments, offscreenToBlobCallback);
+				};
+			}
+		},
+		offscreenToBlob: {
+			name: "toBlob",
+			type: "readout",
+			getStatus: createGetStatus("readout"),
+			object: ["OffscreenCanvas"],
+			fakeGenerator: function(checker){
+				return function toBlob(){
+					return checkerWrapper(checker, this, arguments, offscreenToBlobCallback);
+				};
+			}
+		},
 	};
 	Object.keys(scope.changedFunctions).forEach(function(key){
 		scope.changedFunctions[key].api = "canvas";
diff --git a/lib/settingDefinitions.js b/lib/settingDefinitions.js
index 4bb3a9c..879c985 100644
--- a/lib/settingDefinitions.js
+++ b/lib/settingDefinitions.js
@@ -93,7 +93,9 @@
 				{name: "Canvas-API", level: 1},
 				"getContext @ canvas",
 				{message: "readout", level: 2},
-				"toDataURL @ canvas", "toBlob @ canvas", "mozGetAsFile @ canvas", "getImageData @ canvas",
+				"toDataURL @ canvas",
+				"toBlob @ canvas", "convertToBlob @ canvas", "mozGetAsFile @ canvas",
+				"getImageData @ canvas",
 				"isPointInPath @ canvas", "isPointInStroke @ canvas",
 				{message: "input", level: 2},
 				"fillText @ canvas", "strokeText @ canvas",
diff --git a/releaseNotes.txt b/releaseNotes.txt
index 26820c1..a76b98e 100644
--- a/releaseNotes.txt
+++ b/releaseNotes.txt
@@ -4,6 +4,7 @@ Version 1.3:
 	
 	new features:
 		- added link to FAQ
+		- added offscreen canvas protection
 	
 	fixes:
 		-