Add support for dark mode.

Author: cntrump

ComponentTextKit/CKTextComponentLayer.mm

@@ -85,15 +85,30 @@ - (NSObject *)drawParameters
 
 - (id)willDisplayAsynchronouslyWithDrawParameters:(id<NSObject>)drawParameters
 {
-  return rasterContentsCache()->objectForKey({_renderer.attributes, _renderer.constrainedSize});
+  NSInteger userInterfaceStyle = 1;
+  if (@available(iOS 13.0, *)) {
+    UIView *view = (UIView *)self.delegate;
+    if ([view isKindOfClass:UIView.class]) {
+      userInterfaceStyle = view.traitCollection.userInterfaceStyle;
+    }
+  }
+  return rasterContentsCache()->objectForKey({userInterfaceStyle, _renderer.attributes, _renderer.constrainedSize});
 }
 
 - (void)didDisplayAsynchronously:(id)newContents withDrawParameters:(id<NSObject>)drawParameters
 {
   if (newContents) {
+    NSInteger userInterfaceStyle = 1;
+    if (@available(iOS 13.0, *)) {
+      UIView *view = (UIView *)self.delegate;
+      if ([view isKindOfClass:UIView.class]) {
+        userInterfaceStyle = view.traitCollection.userInterfaceStyle;
+      }
+    }
+
     CGImageRef imageRef = (__bridge CGImageRef)newContents;
     NSUInteger bytes = CGImageGetBytesPerRow(imageRef) * CGImageGetHeight(imageRef);
-    rasterContentsCache()->cacheObject({_renderer.attributes, _renderer.constrainedSize}, newContents, bytes);
+    rasterContentsCache()->cacheObject({userInterfaceStyle, _renderer.attributes, _renderer.constrainedSize}, newContents, bytes);
   }
 }
 

ComponentTextKit/CKTextComponentView.mm

@@ -42,6 +42,17 @@ - (instancetype)initWithFrame:(CGRect)frame
   return self;
 }
 
+- (void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection
+{
+  [super traitCollectionDidChange:previousTraitCollection];
+
+  if (@available(iOS 13.0, *)) {
+    if ([self.traitCollection hasDifferentColorAppearanceComparedToTraitCollection:previousTraitCollection]) {
+        [self.layer setNeedsDisplay];
+    }
+  }
+}
+
 - (void)setBackgroundColor:(UIColor *)backgroundColor
 {
   if (![self.backgroundColor isEqual:backgroundColor]) {

ComponentTextKit/TextKit/CKTextKitRendererCache.h

@@ -67,10 +67,11 @@ namespace CK {
        */
       struct Key {
 
+        NSInteger userInterfaceStyle;
         CKTextKitAttributes attributes;
         CGSize constrainedSize;
 
-        Key(CKTextKitAttributes a, CGSize cs);
+        Key(NSInteger userInterfaceStyle, CKTextKitAttributes a, CGSize cs);
 
         size_t hash;
 
@@ -79,7 +80,8 @@ namespace CK {
           // These comparisons are in a specific order to reduce the overall cost of this function.
           return hash == other.hash
           && CGSizeEqualToSize(constrainedSize, other.constrainedSize)
-          && attributes == other.attributes;
+          && attributes == other.attributes
+          && userInterfaceStyle == other.userInterfaceStyle;
         }
       };
 

ComponentTextKit/TextKit/CKTextKitRendererCache.mm

@@ -26,12 +26,13 @@ void enteredBackgroundNotificationHandler(CFNotificationCenterRef center, void *
     }
 
     namespace Renderer {
-      Key::Key(CKTextKitAttributes a, CGSize cs) : attributes(a), constrainedSize(cs) {
+      Key::Key(NSInteger u, CKTextKitAttributes a, CGSize cs) : userInterfaceStyle(u), attributes(a), constrainedSize(cs) {
         // Precompute hash to avoid paying cost every time getHash is called.
         NSUInteger subhashes[] = {
           attributes.hash(),
           std::hash<CGFloat>()(constrainedSize.width),
-          std::hash<CGFloat>()(constrainedSize.height)
+          std::hash<CGFloat>()(constrainedSize.height),
+          std::hash<NSInteger>()(userInterfaceStyle)
         };
         hash = RCIntegerArrayHash(subhashes, CK_ARRAY_COUNT(subhashes));
       }