Canvas.msToBlob does not match toBlob spec

Issue #7226452 • Assigned to Christian F.


Neil K.
Apr 16, 2016
This issue is public.
Found in
  • Microsoft Edge
  • Internet Explorer
Reported by 3 people

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Steps to reproduce

The Canvas.msToBlob() method returns a Blob but the spec says it should take a callback function that receives the Blob some time later:
void toBlob(FileCallback? _callback, optional DOMString type, any… arguments);


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    Comments and activity

    • Microsoft Edge Team

      Changed Assigned To to “Brad E.”

      Changed Assigned To to “Rick J.”

      Changed Assigned To to “Christian F.”

    • Urgently requesting this feature. It prevents us from supporting high performance image encoding and upload, which is needed for various machine learning / video analysis tasks.

      The asynchronous spec of the standard is important for performance, so that image processing can occur in a separate thread using native implementations rather than blocking the Javascript thread.

      The only workarounds are Javascript wrappers with unacceptable performance (unusable for anything that is working with webcam video).

      WebP image support would be a bonus (it’s 40% smaller than JPEG for equivalent quality in our tests), but JPEG would suffice.

      Many thanks

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