Winit currently implements redrawing in a weird ad-hoc fashion on macOS. This causes a bunch of issues, see rust-windowing/winit#2640 for some of it, which I intend to fix by emitting RedrawRequested in the built-in scheduled draw events (-[NSView drawRect:] / -[NSView updateLayer]) instead.
However, this won't work when the "consumer" of the raw-window-handle that Winit provides (i.e. blade) is overriding the layer on NSView, as is currently done, since that makes the view "layer-hosting", see -[NSView wantsLayer].
The code in question is around here:
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pub unsafe fn from_view(view: *mut Object) -> Self { |
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let main_layer: *mut Object = msg_send![view, layer]; |
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let class = class!(CAMetalLayer); |
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let is_valid_layer: BOOL = msg_send![main_layer, isKindOfClass: class]; |
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let raw_layer = if is_valid_layer == YES { |
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main_layer |
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} else { |
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// If the main layer is not a CAMetalLayer, we create a CAMetalLayer and use it. |
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let new_layer: *mut Object = msg_send![class, new]; |
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let frame: CGRect = msg_send![main_layer, bounds]; |
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let () = msg_send![new_layer, setFrame: frame]; |
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#[cfg(target_os = "ios")] |
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{ |
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// Unlike NSView, UIView does not allow to replace main layer. |
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let () = msg_send![main_layer, addSublayer: new_layer]; |
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let () = msg_send![main_layer, setAutoresizingMask: 0x1Fu64]; |
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let screen: *mut Object = msg_send![class!(UIScreen), mainScreen]; |
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let scale_factor: CGFloat = msg_send![screen, nativeScale]; |
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let () = msg_send![view, setContentScaleFactor: scale_factor]; |
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}; |
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#[cfg(target_os = "macos")] |
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{ |
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let () = msg_send![view, setLayer: new_layer]; |
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let () = msg_send![view, setWantsLayer: YES]; |
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let () = msg_send![new_layer, setContentsGravity: kCAGravityTopLeft]; |
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let window: *mut Object = msg_send![view, window]; |
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if !window.is_null() { |
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let scale_factor: CGFloat = msg_send![window, backingScaleFactor]; |
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let () = msg_send![new_layer, setContentsScale: scale_factor]; |
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} |
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} |
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new_layer |
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}; |
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Self { |
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view: msg_send![view, retain], |
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render_layer: mem::transmute::<_, &metal::MetalLayerRef>(raw_layer).to_owned(), |
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info: crate::SurfaceInfo { |
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format: crate::TextureFormat::Rgba8Unorm, |
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alpha: crate::AlphaMode::Ignored, |
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}, |
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} |
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} |
To fix this, blade should be using -[CALayer addSublayer:] like on iOS instead of -[CALayer setLayer:]. The logic to get resizing to work automatically after this though is a bit cumbersome (you'll need to use observers), so I've extracted it into a crate: raw-window-metal.
I can submit a PR for it if you want, though note that raw-window-metal depends on objc2. If you don't want to use that, you could try to use a similar approach as wgpu currently does, though beware that that still has issues, observers are really the best way to do this (that I've found at least).
