From 7f2dd1d49cc3c0bf5e24fdb37f6457151c1f06c4 Mon Sep 17 00:00:00 2001
From: Saad Najmi <sanajmi@microsoft.com>
Date: Sun, 5 Feb 2023 06:49:08 -0800
Subject: [PATCH] Pull out CGContext early in UIImage+Diff (#35940)

Summary:
This is a small refactor designed to make future merges for React Native macOS easier. It was found while merging React Native 0.71 into React Native macOS.

In React Native macOS, we ifdef iOS  out API's and replace them with macOS APIs, reusing as much code as possible. `CGContext` is a type that is available on both iOS and macOS, but `UIGraphicsImageRendererContext` is not. A simple refactor makes it easier to reuse this code in React Native macOS without affecting iOS :)

Resolves https://github.com/microsoft/react-native-macos/issues/1676

## Changelog

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Pick one each for the category and type tags:

[IOS] [CHANGED] - Pull out CGContext early in UIImage+Diff

Pull Request resolved: https://github.com/facebook/react-native/pull/35940

Test Plan: Build should pass.

Reviewed By: matrush

Differential Revision: D42761424

Pulled By: javache

fbshipit-source-id: 5ce79a5e7c60484dd37d0b2c3f58ff0897d662df
---
 .../RCTTest/FBSnapshotTestCase/UIImage+Diff.m     | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/packages/rn-tester/RCTTest/FBSnapshotTestCase/UIImage+Diff.m b/packages/rn-tester/RCTTest/FBSnapshotTestCase/UIImage+Diff.m
index 5713d4b74c5ef8..178f988fa595c3 100644
--- a/packages/rn-tester/RCTTest/FBSnapshotTestCase/UIImage+Diff.m
+++ b/packages/rn-tester/RCTTest/FBSnapshotTestCase/UIImage+Diff.m
@@ -21,15 +21,16 @@ - (UIImage *)diffWithImage:(UIImage *)image
   UIGraphicsImageRenderer *const renderer = [[UIGraphicsImageRenderer alloc] initWithSize:imageSize
                                                                                    format:rendererFormat];
 
-  return [renderer imageWithActions:^(UIGraphicsImageRendererContext *_Nonnull context) {
+  return [renderer imageWithActions:^(UIGraphicsImageRendererContext *_Nonnull rendererContext) {
+    const CGContextRef context = rendererContext.CGContext;
     [self drawInRect:CGRectMake(0, 0, self.size.width, self.size.height)];
-    CGContextSetAlpha(context.CGContext, 0.5f);
-    CGContextBeginTransparencyLayer(context.CGContext, NULL);
+    CGContextSetAlpha(context, 0.5f);
+    CGContextBeginTransparencyLayer(context, NULL);
     [image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];
-    CGContextSetBlendMode(context.CGContext, kCGBlendModeDifference);
-    CGContextSetFillColorWithColor(context.CGContext, [UIColor whiteColor].CGColor);
-    CGContextFillRect(context.CGContext, CGRectMake(0, 0, self.size.width, self.size.height));
-    CGContextEndTransparencyLayer(context.CGContext);
+    CGContextSetBlendMode(context, kCGBlendModeDifference);
+    CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
+    CGContextFillRect(context, CGRectMake(0, 0, self.size.width, self.size.height));
+    CGContextEndTransparencyLayer(context);
   }];
 }