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Debounce the resize event handler #19612

merged 1 commit into from Jun 28, 2019


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commented Jun 28, 2019


Atom is currently listening to window resize events to store the window width/height and position and be able to restore the window dimensions when it gets reopened.

In order to do so, the resize handler is doing the following:

  • Get the current BrowserWindow object from the main process (synchronous IPC call).
  • Get the BrowserWindow size from the main process (synchronous IPC call).
  • Get the BrowserWindow position from the main process (synchronous IPC call).
  • Validate that data is correct.
  • Serialize the data into JSON and store it on localStorage (all synchronous).

All this processing usually takes 2-5ms on my high end machine, but under some circumstances (don't know what triggers it) it can take 40-50ms (or even up to 200-400ms, for example on Electron v4 because of electron/electron#19027). These times are way above the frame budget and cause very noticeable lagging on the UI when resizing.


The solution is a one-line change: just using a simple debouncer to only store the windows dimensions when the resizing has finished makes the UI lag-free.

Here there's a comparison video between current master and this PR, to see the noticeable difference (I didn't upload a gif since it cannot be appreciated well with that format due to the framerate).


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commented Jun 28, 2019

Probably there are some failing tests... I'll leave CI to discover them for me 🙃

@rafeca rafeca force-pushed the debounce-resize-event branch from f81fe5a to 7593d49 Jun 28, 2019

@rafeca rafeca merged commit 401248d into master Jun 28, 2019

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Atom Pull Requests #20190628.2 succeeded

@rafeca rafeca deleted the debounce-resize-event branch Jun 29, 2019


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commented Jul 1, 2019

Wow, this simple change suddenly makes Atom feel like a native app. Nice and thanks! ❤️ 🚀

rafeca added a commit that referenced this pull request Jul 2, 2019

Merge pull request #19612 from atom/debounce-resize-event
Debounce the resize event handler
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