Custom cursor tracking issue

[daxpedda]

Custom cursors are still missing some refinements.

Known Issues

• On Web, correctly handle multiple windows waiting on the same cursor: Web: improve custom cursor loading #3321.
• On Wayland, account for alpha: On Wayland, custom cursors don't respect alpha #3360.
• Figure out how to prevent CustomCursors to outlive the event loop. This is similar to WindowHandle is not sound #3317 and MonitorHandle and VideoMode can become invalid leading to panics #3258.

Improvements

• Add back Window::set_cursor_icon() as a deprecated method: Add deprecated Window::set_cursor_icon() #3329.
• Merge icons and cursors in one type and one method: Merge Window::set_cursor_icon() and Window::set_custom_cursor() #3308.
• Add a cursor getter/setter on WindowBuilder: Add WindowBuilder::with_cursor() #3319.
• Add a cursor getter on Window.
• Make sure implementations check if the new cursor being set isn't the same already set.
  • MacOS: MacOS: check if cursor changed before applying #3324.
  • Wayland
  • Web: Web: improve custom cursor loading #3321.
  • Windows
  • X11
• Return a Result at CustomCursorBuilder::build(), AFAIK only Windows needs it.
• On Windows, extension method to load from a resource, like in Icon::from_resource().
• On Web, async fn build() extension method to wait until the cursor has successfully finished loading: Web: improve custom cursor handling and add animated cursors #3384.

Caching

• MacOS: MacOS: cache custom cursor #3291
• Wayland
• Web: Allow custom cursor caching #3276
• Windows: Windows: cache custom cursor #3293
• X11: X11: cache custom cursors #3366

Animation

• Web: Web: improve custom cursor handling and add animated cursors #3384
• Windows: support ANI files (loaded from memory or otherwise).
• MacOS: Use NSTimer? (idea from Firefox)
• X11: XcursorAnimate

[kchibisov]

On Wayland you animate the cursor yourself and you generally supply the Xcursor formatted cursor.

So you should have a bunch of frames and delays between the frames.

[kchibisov]

That's how it looks.

https://www.x.org/releases/X11R7.7/doc/man/man3/Xcursor.3.xhtml

So basically the custom cursor is

struct CustomCursor {
    hotspot_x: i16,
    hotspot_y: i16,
    width: i16,
    height: i16,
    delay: Duration,
    images: Vec<RGBA>,
}