Bug 185635 - Web Inspector: Canvas: it takes over a minute to process a 2 second recording
Summary: Web Inspector: Canvas: it takes over a minute to process a 2 second recording
Alias: None
Product: WebKit
Classification: Unclassified
Component: Web Inspector (show other bugs)
Version: WebKit Nightly Build
Hardware: All All
: P2 Normal
Assignee: Matt Baker
Keywords: InRadar
Depends on: 185758
Blocks: WebInspectorCanvasRecording
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Reported: 2018-05-14 17:38 PDT by Nikita Vasilyev
Modified: 2018-05-18 14:08 PDT (History)
4 users (show)

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Description Nikita Vasilyev 2018-05-14 17:38:37 PDT
1. Go to http://www.blobsallad.se
2. Open Canvas tab in Web Inspector
3. Press the record button for the Blob canvas
4. Wait for two seconds
5. Press the stop button

It took over a minute to show the recording. "Processing recording" stayed on for over a minute.

The recording shows in a few seconds. If that isn't possible, it should show the recording with limited features at first.
Comment 1 Radar WebKit Bug Importer 2018-05-14 17:38:57 PDT
Comment 2 Devin Rousso 2018-05-15 01:23:35 PDT
This is most likely caused by <https://webkit.org/b/175282>.  There is no "easy" way to quickly determine if a particular visual action caused some pixels to change on the canvas, so we have to resort to checking every single pixel.  On larger canvases, this can take a long time, and the problem is compounded if there are a large number of visual actions in the recording.
Comment 3 Matt Baker 2018-05-18 14:08:13 PDT
This was addressed in https://bugs.webkit.org/show_bug.cgi?id=185758.