Alpha channel halved when calling CanvasRenderingContext2d clearRect(), drawImage(HTMLCanvasElement)

By design Issue #6768363

Details

Created
Mar 4, 2016
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This issue is public.
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Steps to reproduce

URL:

Repro Steps:

  1. create 2 canvases
  2. draw text with a shadow on A, then call clearRect() to clear the entire canvas. (Canvas A is actually 100% clear at this point)
  3. draw text with shadow on B, then call A.drawImage(B);

Expected Results:

Images on both canvases should have the same alpha. Canvas A and B should have identical images.

Actual Results:

Dev Channel specific:

No

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    Comments and activity

    • Microsoft Edge Team

      Changed Assigned To to “Mara P.”

      Changed Assigned To to “Christian F.”

      Changed Assigned To from “Christian F.” to “Li-Hsin H.”

      Changed Status to “Confirmed”

    • Please disregard this bug. Is mistaken about how the .shadow* properties work, the “problem” was in my code. I thought the Sofie properties should only affect text, but they also affect .drawImage() calls (as intended by the spec)

    • Please disregard this bug. I was mistaken about how the .shadow* properties work, the “problem” was in my code. I thought the shadow properties should only affect text, but they also affect .drawImage() calls (as intended by the spec)

    • Microsoft Edge Team

      Changed Assigned To from “Li-Hsin H.” to “IE S.”

      Changed Status from “Confirmed” to “By design”

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