feat: Introduce RCTUIImage (2/2)#2766
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## Summary: This PR is split out from #2766 to help make it smaller. Previously we had the code `@compatibility_alias UIImage NSImage` which is basically an objective C runtime way of doing `#define UIImage NSImage`. We don't quite like this, since we are defining the symbol `UIImage` in an Appkit context. We have a better pattern we can copy from RCTPlatformView --> RCTPlatformImage. The `RCTPlatform` prefix basically means it's NS<blah> on Appkit and UI<blah> on UIKit. This is as opposed to something like RCTUIView, where on iOS it's a typedef, but on macOS it's a subclass that adds stuff to NSView to make it more compatible with UIView. All in all, this should mostly be a rigorous find/replace to make the code slightly more strict, but have no behavioral changes ## Test Plan: RNTester runs locally.
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Summary:
Needs #2783 to merge first.
Resolves #2738
There were a couple of issues with our macOS image rendering code that caused borders and shadows to not render properly in Fabric:
UIGraphicsImageRendereron macOS (RCTUIGraphicsImageRenderer) called[NSImage imageWithActions:flipped:drawingHandler], which would not render the imade right away but instead when it's about to be displayed (presumably so that it can generate a properCGContextfor the screen the image is on). This meant that CGImage bitmap would sometimes just return as0x0NSImageunlikeUIImagedoes not have aCGImageproperty, so we used the methodCGImageForProposedRect:to get one. Unfortunately, that returns an autoreleased CGImage, and when we later set that to RCTViewComponentViews'layer.contents, it would not be retained.This manifested as borders and shadows not rendering, or rendering and then dissapearing on a resize.
To fix the first issue, apparently we can just call
[image lockFocus]and[image unlockFocus]in succession to force it to render a bitmap.To fix the second issue, we need some way to cache the CGImage. I propose a new class:
RCTUIImage.RCTUIImage, likeRCTUIViewis a subclass ofNSImagewith some extra properties and methods to make it more compatible with iOS code. In our case, we add the extra code to cache a CGImage, with proper retain and release calls. We can then haveRCTUIGraphicsImageRendererreturn our new subclass, and update all callers appropiately. The end result it we can actually remove some diffs, and have our macOS image handling behave closer to iOS.While doing this work, I realized our
NSImage/UIImageshims were kinda messy, and with the new subclass to introduce weird runtime edge cases. I split out #2783 to help clean up and clarify what image class we're using in the rest of the codebase.While here, I also fixed an issue with clipsToBounds on macOS which was the final piece to get shadows and borders working.
Test Plan:
RNTester seems better :)
Screen.Recording.2025-11-26.at.3.39.04.PM.mov