[Webkit-unassigned] [Bug 209899] New: Blank WebGL Canvas when element is shown after hiding (Safari)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=209899

            Bug ID: 209899
           Summary: Blank WebGL Canvas when element is shown after hiding
                    (Safari)
           Product: WebKit
           Version: Safari 13
          Hardware: All
                OS: All
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Canvas
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: tom.chan at cambridge-intelligence.com
                CC: dino at apple.com

Created attachment 395253

  --> https://bugs.webkit.org/attachment.cgi?id=395253&action=review

app showing safari webGL canvas drawing bug

When you reshow a WebGL canvas element, the contents are not always drawn and you sometimes just get a blank canvas.
This issue only seems to be present on Safari.

Reproduction steps:
1. Create a canvas element using WebGL to draw.
2. Hide that element using "display: none".
3. Reshow the element using "display: block".

Current Behaviour:
Repetitive trials indicate that the canvas content is only restored about 50% of the time.

Expected Behaviour:
The canvas element's content, i.e. what is drawn on the canvas, should be redrawn when the element is re-shown in all instances.


Other:
See attached zip for a simple app that demonstrates this.

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