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authorThibG <thib@sitedethib.com>2019-08-06 12:08:19 +0200
committerEugen Rochko <eugen@zeonfederated.com>2019-08-06 12:08:19 +0200
commit111a0628fc161df4d76967d7dc7116b8a43fe8e2 (patch)
treee66ae45fb4c9a43853f0e793d109860c65cdc6b8
parent27a0d02d0d960163e98595b05412c0d03a4875d0 (diff)
Fix image uploads being perfectly white when canvas read access is blocked (#11499)
Fixes #11496
-rw-r--r--app/javascript/mastodon/utils/resize_image.js8
1 files changed, 8 insertions, 0 deletions
diff --git a/app/javascript/mastodon/utils/resize_image.js b/app/javascript/mastodon/utils/resize_image.js
index bbdbc865e..a8ec5f3fa 100644
--- a/app/javascript/mastodon/utils/resize_image.js
+++ b/app/javascript/mastodon/utils/resize_image.js
@@ -67,6 +67,14 @@ const processImage = (img, { width, height, orientation, type = 'image/png' }) =
 
   context.drawImage(img, 0, 0, width, height);
 
+  // The Tor Browser and maybe other browsers may prevent reading from canvas
+  // and return an all-white image instead. Assume reading failed if the resized
+  // image is perfectly white.
+  const imageData = context.getImageData(0, 0, width, height);
+  if (imageData.every(value => value === 255)) {
+    throw 'Failed to read from canvas';
+  }
+
   canvas.toBlob(resolve, type);
 });