Share a singleton shadower for all cases when shadow isn't drawn, fix issues (#2511)

AsyncDisplayKit/ASTextNode.mm

@@ -102,10 +102,7 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   if (self = [super init]) {
     // Load default values from superclass.
     _shadowOffset = [super shadowOffset];
-    CGColorRef superColor = [super shadowColor];
-    if (superColor != NULL) {
-      _shadowColor = CGColorRetain(superColor);
-    }
+    _shadowColor = CGColorRetain([super shadowColor]);
     _shadowOpacity = [super shadowOpacity];
     _shadowRadius = [super shadowRadius];
 
@@ -140,10 +137,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)dealloc
 {
-  if (_shadowColor != NULL) {
-    CGColorRelease(_shadowColor);
-  }
-  
+  CGColorRelease(_shadowColor);
+
   [self _invalidateRenderer];
 
   if (_longPressGestureRecognizer) {
@@ -548,9 +543,6 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   CGContextTranslateCTM(context, _textContainerInset.left, _textContainerInset.top);
   
   ASTextKitRenderer *renderer = [self _rendererWithBounds:drawParameterBounds];
-  UIEdgeInsets shadowPadding = [self shadowPaddingWithRenderer:renderer];
-  CGPoint boundsOrigin = drawParameterBounds.origin;
-  CGPoint textOrigin = CGPointMake(boundsOrigin.x - shadowPadding.left, boundsOrigin.y - shadowPadding.top);
   
   // Fill background
   if (backgroundColor != nil) {
@@ -558,12 +550,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
     UIRectFillUsingBlendMode(CGContextGetClipBoundingBox(context), kCGBlendModeCopy);
   }
   
-  // Draw shadow
-  [renderer.shadower setShadowInContext:context];
-  
   // Draw text
-  bounds.origin = textOrigin;
-  [renderer drawInContext:context bounds:bounds];
+  [renderer drawInContext:context bounds:drawParameterBounds];
   
   CGContextRestoreGState(context);
 }
@@ -1133,14 +1121,9 @@ static CGRect ASTextNodeAdjustRenderRectForShadowPadding(CGRect rendererRect, UI
 {
   ASDN::MutexLocker l(__instanceLock__);
   
-  if (_shadowColor != shadowColor) {
-    if (shadowColor != NULL) {
-      CGColorRetain(shadowColor);
-    }
-    if (_shadowColor != NULL) {
-      CGColorRelease(_shadowColor);
-    }
-    _shadowColor = shadowColor;
+  if (_shadowColor != shadowColor && CGColorEqualToColor(shadowColor, _shadowColor) == NO) {
+    CGColorRelease(_shadowColor);
+    _shadowColor = CGColorRetain(shadowColor);
     _cachedShadowUIColor = [UIColor colorWithCGColor:shadowColor];
     [self _invalidateRenderer];
     [self setNeedsDisplay];

AsyncDisplayKit/TextKit/ASTextKitAttributes.h

@@ -59,7 +59,7 @@ struct ASTextKitAttributes {
   /**
    An array of UIBezierPath objects representing the exclusion paths inside the receiver's bounding rectangle. Default value: nil.
    */
-  NSArray *exclusionPaths;
+  NSArray<UIBezierPath *> *exclusionPaths;
   /**
    The shadow offset for any shadows applied to the text.  The coordinate space for this is the same as UIKit, so a
    positive width means towards the right, and a positive height means towards the bottom.

AsyncDisplayKit/TextKit/ASTextKitRenderer.mm

@@ -68,10 +68,10 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
 {
   if (!_shadower) {
     ASTextKitAttributes attributes = _attributes;
-    _shadower = [[ASTextKitShadower alloc] initWithShadowOffset:attributes.shadowOffset
-                                                    shadowColor:attributes.shadowColor
-                                                  shadowOpacity:attributes.shadowOpacity
-                                                   shadowRadius:attributes.shadowRadius];
+    _shadower = [ASTextKitShadower shadowerWithShadowOffset:attributes.shadowOffset
+                                                shadowColor:attributes.shadowColor
+                                              shadowOpacity:attributes.shadowOpacity
+                                               shadowRadius:attributes.shadowRadius];
   }
   return _shadower;
 }

AsyncDisplayKit/TextKit/ASTextKitShadower.h

@@ -15,10 +15,10 @@
  */
 @interface ASTextKitShadower : NSObject
 
-- (instancetype)initWithShadowOffset:(CGSize)shadowOffset
-                         shadowColor:(UIColor *)shadowColor
-                       shadowOpacity:(CGFloat)shadowOpacity
-                        shadowRadius:(CGFloat)shadowRadius;
++ (ASTextKitShadower *)shadowerWithShadowOffset:(CGSize)shadowOffset
+                                    shadowColor:(UIColor *)shadowColor
+                                  shadowOpacity:(CGFloat)shadowOpacity
+                                   shadowRadius:(CGFloat)shadowRadius;
 
 /**
  * @abstract The offset from the top-left corner at which the shadow starts.

AsyncDisplayKit/TextKit/ASTextKitShadower.mm

@@ -14,7 +14,9 @@
 
 static inline CGSize _insetSize(CGSize size, UIEdgeInsets insets)
 {
-  return UIEdgeInsetsInsetRect({.size = size}, insets).size;
+  size.width -= (insets.left + insets.right);
+  size.height -= (insets.top + insets.bottom);
+  return size;
 }
 
 static inline UIEdgeInsets _invertInsets(UIEdgeInsets insets)
@@ -31,6 +33,28 @@ static inline UIEdgeInsets _invertInsets(UIEdgeInsets insets)
   UIEdgeInsets _calculatedShadowPadding;
 }
 
++ (ASTextKitShadower *)shadowerWithShadowOffset:(CGSize)shadowOffset
+                                    shadowColor:(UIColor *)shadowColor
+                                  shadowOpacity:(CGFloat)shadowOpacity
+                                   shadowRadius:(CGFloat)shadowRadius
+{
+  /**
+   * For all cases where no shadow is drawn, we share this singleton shadower to save resources.
+   */
+  static dispatch_once_t onceToken;
+  static ASTextKitShadower *sharedNonShadower;
+  dispatch_once(&onceToken, ^{
+    sharedNonShadower = [[ASTextKitShadower alloc] initWithShadowOffset:CGSizeZero shadowColor:nil shadowOpacity:0 shadowRadius:0];
+  });
+
+  BOOL hasShadow = shadowOpacity > 0 && (shadowRadius > 0 || CGSizeEqualToSize(shadowOffset, CGSizeZero) == NO) && CGColorGetAlpha(shadowColor.CGColor) > 0;
+  if (hasShadow == NO) {
+    return sharedNonShadower;
+  } else {
+    return [[ASTextKitShadower alloc] initWithShadowOffset:shadowOffset shadowColor:shadowColor shadowOpacity:shadowOpacity shadowRadius:shadowRadius];
+  }
+}
+
 - (instancetype)initWithShadowOffset:(CGSize)shadowOffset
                          shadowColor:(UIColor *)shadowColor
                        shadowOpacity:(CGFloat)shadowOpacity
@@ -52,7 +76,7 @@ static inline UIEdgeInsets _invertInsets(UIEdgeInsets insets)
  */
 - (BOOL)_shouldDrawShadow
 {
-  return _shadowOpacity != 0.0 && _shadowColor != nil && (_shadowRadius != 0 || !CGSizeEqualToSize(_shadowOffset, CGSizeZero));
+  return _shadowOpacity != 0.0 && (_shadowRadius != 0 || !CGSizeEqualToSize(_shadowOffset, CGSizeZero)) && CGColorGetAlpha(_shadowColor.CGColor) > 0;
 }
 
 - (void)setShadowInContext:(CGContextRef)context

AsyncDisplayKitTests/ASTextNodeSnapshotTests.m

@@ -92,4 +92,16 @@
   ASSnapshotVerifyNode(textNode, nil);
 }
 
+- (void)testShadowing
+{
+  ASTextNode *textNode = [[ASTextNode alloc] init];
+  textNode.attributedText = [[NSAttributedString alloc] initWithString:@"Quality is Important"];
+  textNode.shadowColor = [UIColor blackColor].CGColor;
+  textNode.shadowOpacity = 0.3;
+  textNode.shadowRadius = 3;
+  textNode.shadowOffset = CGSizeMake(0, 1);
+  [textNode layoutThatFits:ASSizeRangeMake(CGSizeZero, CGSizeMake(CGFLOAT_MAX, CGFLOAT_MAX))];
+  ASSnapshotVerifyNode(textNode, nil);
+}
+
 @end