Avoid an explicit CATransaction commit

These are expensive, and the layer should be able to figure out the
timing of when to render by itself.

Author: madsmtm

src/backends/cg.rs

@@ -3,18 +3,18 @@ use crate::backend_interface::*;
 use crate::error::InitError;
 use crate::{Rect, SoftBufferError};
 use objc2::rc::Retained;
-use objc2::runtime::{AnyObject, Bool};
+use objc2::runtime::{AnyObject, Bool, ProtocolObject};
 use objc2::{define_class, msg_send, AllocAnyThread, DefinedClass, MainThreadMarker, Message};
 use objc2_core_foundation::{CFRetained, CGPoint};
 use objc2_core_graphics::{
     CGBitmapInfo, CGColorRenderingIntent, CGColorSpace, CGDataProvider, CGImage, CGImageAlphaInfo,
 };
 use objc2_foundation::{
     ns_string, NSDictionary, NSKeyValueChangeKey, NSKeyValueChangeNewKey,
-    NSKeyValueObservingOptions, NSNumber, NSObject, NSObjectNSKeyValueObserverRegistration,
+    NSKeyValueObservingOptions, NSNull, NSNumber, NSObject, NSObjectNSKeyValueObserverRegistration,
     NSString, NSValue,
 };
-use objc2_quartz_core::{kCAGravityTopLeft, CALayer, CATransaction};
+use objc2_quartz_core::{kCAGravityTopLeft, CALayer};
 use raw_window_handle::{HasDisplayHandle, HasWindowHandle, RawWindowHandle};
 
 use std::ffi::c_void;
@@ -222,6 +222,17 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> SurfaceInterface<D, W> for CGImpl<
         // resized to something that doesn't fit, see #177.
         layer.setContentsGravity(unsafe { kCAGravityTopLeft });
 
+        // 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.
+        //
+        // We avoid this by setting the action for the "contents" key to NULL.
+        //
+        // TODO(madsmtm): Do we want to do the same for bounds/contentsScale for smoother resizing?
+        layer.setActions(Some(&NSDictionary::from_slices(
+            &[ns_string!("contents")],
+            &[ProtocolObject::from_ref(&*unsafe { NSNull::null() })],
+        )));
+
         // Initialize color space here, to reduce work later on.
         let color_space = unsafe { CGColorSpace::new_device_rgb() }.unwrap();
 
@@ -326,16 +337,9 @@ impl<D: HasDisplayHandle, W: HasWindowHandle> BufferInterface for BufferImpl<'_,
         }
         .unwrap();
 
-        // 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 avoided by wrapping the operation in a transaction and disabling all actions.
-        CATransaction::begin();
-        CATransaction::setDisableActions(true);
-
         // SAFETY: The contents is `CGImage`, which is a valid class for `contents`.
         unsafe { self.imp.layer.setContents(Some(image.as_ref())) };
 
-        CATransaction::commit();
         Ok(())
     }