prevent costumes with imported CORS-tainted canvases

expected to fix #155, #154, #151, #148, #147, #127 for future projects

1 files changed, 19 insertions, 1 deletions

diff --git a/objects.js b/objects.js
index 9e61d58..398a61d 100644
--- a/objects.js
+++ b/objects.js
@@ -124,7 +124,7 @@ PrototypeHatBlockMorph*/
 
 // Global stuff ////////////////////////////////////////////////////////
 
-modules.objects = '2013-September-17';
+modules.objects = '2013-September-18';
 
 var SpriteMorph;
 var StageMorph;
@@ -5246,6 +5246,24 @@ Costume.prototype.thumbnail = function (extentPoint) {
     return trg;
 };
 
+// Costume catching "tainted" canvases
+
+Costume.prototype.isTainted = function () {
+    // find out whether the canvas has been tainted by cross-origin data
+    // assumes that if reading image data throws an error it is tainted
+    try {
+        this.contents.getContext('2d').getImageData(
+            0,
+            0,
+            this.contents.width,
+            this.contents.height
+        );
+    } catch (err) {
+        return true;
+    }
+    return false;
+};
+
 // SVG_Costume /////////////////////////////////////////////////////////////
 
 /*