rust-windowing / rust-windowing/winit

macOS mouse events are laggy

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#2,240 3 comments 4 reactions 0 assignees View on GitHub

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B - bug DS - appkit
Dominant language
Rust
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Description

  • macOS 11.5.2
  • winit 0.26.1

Scroll and mouse move events on macOS feel like they run at a substantially lower frame rate than the window. This is exhibited in this wgpu tutorial. Near the bottom of the page, there is a "Try Tutorial12_camera" button, which opens up the demo. Scrolling on the demo in-browser is smooth, but when compiling and running it as a native application on macOS, scrolling (and dragging) is laggy.

I'm running into this issue in a different project (also using wgpu), so it's not specific to that particular demo. Using keyboard keys in both the web and native versions results in smooth frame rates, so it's not the demo itself that is running slower.

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Research direction

Reproduce the lag in the linked wgpu Tutorial12_camera native application on macOS, comparing scroll and mouse-move events with the smooth browser and keyboard behavior. Trace the macOS event handling path in winit and identify where input updates fall behind the window; the issue is done when native scrolling and dragging are responsive without regressing keyboard input.

Written by the indexing model from the issue text.

Assessment

Tech stack
macos, rust
Domain
desktop, operating-systems
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
30/100

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