deps: Use objc2

Fixes #181.

This also prevents accessing the `NSView`/`NSWindow` from other threads than the main thread.

SoftBufferError is `#[non_exhaustive]`, so it's fine to add further
variants to it. I decided against doing that though, as the error is
platform-specific, and not one that the program can really handle in any
reasonable way (it's closer to a programmer error).

Author: madsmtm

Cargo.toml

@@ -47,10 +47,12 @@ features = ["Win32_Graphics_Gdi", "Win32_UI_WindowsAndMessaging", "Win32_Foundat
 
 [target.'cfg(target_os = "macos")'.dependencies]
 bytemuck = { version = "1.12.3", features = ["extern_crate_alloc"] }
-cocoa = "0.25.0"
 core-graphics = "0.23.1"
 foreign-types = "0.5.0"
-objc = "0.2.7"
+objc2 = "0.5.1"
+objc2-foundation = { version = "0.2.0", features = ["NSThread"] }
+objc2-app-kit = { version = "0.2.0", features = ["NSResponder", "NSView", "NSWindow"] }
+objc2-quartz-core = { version = "0.2.0", features = ["CALayer", "CATransaction"] }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 js-sys = "0.3.63"
@@ -119,4 +121,3 @@ targets = [
     "x86_64-unknown-linux-gnu",
     "wasm32-unknown-unknown",
 ]
-

src/backends/cg.rs

@@ -7,12 +7,15 @@ use core_graphics::base::{
 use core_graphics::color_space::CGColorSpace;
 use core_graphics::data_provider::CGDataProvider;
 use core_graphics::image::CGImage;
+use objc2::runtime::AnyObject;
 use raw_window_handle::{HasDisplayHandle, HasWindowHandle, RawWindowHandle};
 
-use cocoa::appkit::{NSView, NSViewHeightSizable, NSViewWidthSizable, NSWindow};
-use cocoa::base::{id, nil};
-use cocoa::quartzcore::{transaction, CALayer, ContentsGravity};
 use foreign_types::ForeignType;
+use objc2::msg_send;
+use objc2::rc::Id;
+use objc2_app_kit::{NSAutoresizingMaskOptions, NSView, NSWindow};
+use objc2_foundation::MainThreadMarker;
+use objc2_quartz_core::{kCAGravityTopLeft, CALayer, CATransaction};
 
 use std::marker::PhantomData;
 use std::num::NonZeroU32;
@@ -27,14 +30,19 @@ impl AsRef<[u8]> for Buffer {
 }
 
 pub struct CGImpl<D, W> {
-    layer: CALayer,
-    window: id,
+    layer: Id<CALayer>,
+    window: Id<NSWindow>,
     color_space: CGColorSpace,
     size: Option<(NonZeroU32, NonZeroU32)>,
     window_handle: W,
     _display: PhantomData<D>,
 }
 
+// TODO(madsmtm): Expose this in `objc2_app_kit`.
+fn set_layer(view: &NSView, layer: &CALayer) {
+    unsafe { msg_send![view, setLayer: layer] }
+}
+
 impl<D: HasDisplayHandle, W: HasWindowHandle> SurfaceInterface<D, W> for CGImpl<D, W> {
     type Context = D;
     type Buffer<'a> = BufferImpl<'a, D, W> where Self: 'a;
@@ -45,20 +53,35 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> SurfaceInterface<D, W> for CGImpl<
             RawWindowHandle::AppKit(handle) => handle,
             _ => return Err(InitError::Unsupported(window_src)),
         };
-        let view = handle.ns_view.as_ptr() as id;
-        let window: id = unsafe { msg_send![view, window] };
-        let window: id = unsafe { msg_send![window, retain] };
+
+        // `NSView` can only be accessed from the main thread.
+        let mtm = MainThreadMarker::new().ok_or(SoftBufferError::PlatformError(
+            Some("can only access AppKit / macOS handles from the main thread".to_string()),
+            None,
+        ))?;
+        let view = handle.ns_view.as_ptr();
+        // SAFETY: The pointer came from `WindowHandle`, which ensures that
+        // the `AppKitWindowHandle` contains a valid pointer to an `NSView`.
+        // Unwrap is fine, since the pointer came from `NonNull`.
+        let view: Id<NSView> = unsafe { Id::retain(view.cast()) }.unwrap();
         let layer = CALayer::new();
+        let subview = unsafe { NSView::initWithFrame(mtm.alloc(), view.frame()) };
+        layer.setContentsGravity(unsafe { kCAGravityTopLeft });
+        layer.setNeedsDisplayOnBoundsChange(false);
+        set_layer(&subview, &layer);
         unsafe {
-            let subview: id = NSView::alloc(nil).initWithFrame_(NSView::frame(view));
-            layer.set_contents_gravity(ContentsGravity::TopLeft);
-            layer.set_needs_display_on_bounds_change(false);
-            subview.setLayer(layer.id());
-            subview.setAutoresizingMask_(NSViewWidthSizable | NSViewHeightSizable);
-
-            view.addSubview_(subview); // retains subview (+1) = 2
-            let _: () = msg_send![subview, release]; // releases subview (-1) = 1
-        }
+            subview.setAutoresizingMask(NSAutoresizingMaskOptions(
+                NSAutoresizingMaskOptions::NSViewWidthSizable.0
+                    | NSAutoresizingMaskOptions::NSViewHeightSizable.0,
+            ))
+        };
+
+        let window = view.window().ok_or(SoftBufferError::PlatformError(
+            Some("view must be inside a window".to_string()),
+            None,
+        ))?;
+
+        unsafe { view.addSubview(&subview) };
         let color_space = CGColorSpace::create_device_rgb();
         Ok(Self {
             layer,
@@ -131,17 +154,20 @@ impl<'a, D: HasDisplayHandle, W: HasWindowHandle> BufferInterface for BufferImpl
         // The CALayer has a default action associated with a change in the layer contents, causing
         // a quarter second fade transition to happen every time a new buffer is applied. This can
         // be mitigated by wrapping the operation in a transaction and disabling all actions.
-        transaction::begin();
-        transaction::set_disable_actions(true);
+        CATransaction::begin();
+        CATransaction::setDisableActions(true);
+
+        self.imp
+            .layer
+            .setContentsScale(self.imp.window.backingScaleFactor());
 
         unsafe {
             self.imp
                 .layer
-                .set_contents_scale(self.imp.window.backingScaleFactor());
-            self.imp.layer.set_contents(image.as_ptr() as id);
+                .setContents((image.as_ptr() as *mut AnyObject).as_ref());
         };
 
-        transaction::commit();
+        CATransaction::commit();
 
         Ok(())
     }
@@ -150,11 +176,3 @@ impl<'a, D: HasDisplayHandle, W: HasWindowHandle> BufferInterface for BufferImpl
         self.present()
     }
 }
-
-impl<D, W> Drop for CGImpl<D, W> {
-    fn drop(&mut self) {
-        unsafe {
-            let _: () = msg_send![self.window, release];
-        }
-    }
-}

src/lib.rs

@@ -3,9 +3,6 @@
 #![warn(missing_docs)]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
 
-#[cfg(target_os = "macos")]
-#[macro_use]
-extern crate objc;
 extern crate core;
 
 mod backend_dispatch;