[AsyncDisplayKit+Debug.h] Moving hitTestDebug tool code out of ASControlNode and into debug file

- unifying ASControlNode, ASImageNode debugging categories into debug file to simplify base classes

AsyncDisplayKit/AsyncDisplayKit+Debug.m

@@ -8,6 +8,7 @@
 
 #import "AsyncDisplayKit+Debug.h"
 #import "ASDisplayNode+Subclasses.h"
+#import "ASDisplayNodeExtras.h"
 
 static BOOL __shouldShowImageScalingOverlay = NO;
 
@@ -24,3 +25,165 @@ static BOOL __shouldShowImageScalingOverlay = NO;
 }
 
 @end
+
+static BOOL __enableHitTestDebug = NO;
+
+@interface ASControlNode (Debugging)
+
+- (ASImageNode *)debugHighlightOverlay;
+
+@end
+
+@implementation ASControlNode (Debugging)
+
++ (void)setEnableHitTestDebug:(BOOL)enable
+{
+  __enableHitTestDebug = enable;
+}
+
++ (BOOL)enableHitTestDebug
+{
+  return __enableHitTestDebug;
+}
+
+// layout method required ONLY when hitTestDebug is enabled
+- (void)layout
+{
+  [super layout];
+  
+  if ([ASControlNode enableHitTestDebug]) {
+    
+    // Construct hitTestDebug highlight overlay frame indicating tappable area of a node, which can be restricted by two things:
+    
+    // (1) Any parent's tapable area (its own bounds + hitTestSlop) may restrict the desired tappable area expansion using
+    // hitTestSlop of a child as UIKit event delivery (hitTest:) will not search sub-hierarchies if one of our parents does
+    // not return YES for pointInside:. To circumvent this restriction, a developer will need to set / adjust the hitTestSlop
+    // on the limiting parent. This is indicated in the overlay by a dark GREEN edge. This is an ACTUAL restriction.
+    
+    // (2) Any parent's .clipToBounds. If a parent is clipping, we cannot show the overlay outside that area
+    // (although it still respond to touch). To indicate that the overlay cannot accurately display the true tappable area,
+    // the overlay will have an ORANGE edge. This is a VISUALIZATION restriction.
+    
+    CGRect intersectRect                 = UIEdgeInsetsInsetRect(self.bounds, [self hitTestSlop]);
+    UIRectEdge clippedEdges              = UIRectEdgeNone;
+    UIRectEdge clipsToBoundsClippedEdges = UIRectEdgeNone;
+    CALayer *layer               = self.layer;
+    CALayer *intersectLayer      = layer;
+    CALayer *intersectSuperlayer = layer.superlayer;
+    
+    // FIXED: Stop climbing hierarchy if UIScrollView is encountered (its offset bounds origin may make it seem like our events
+    // will be clipped when scrolling will actually reveal them (because this process will not re-run due to scrolling))
+    while (intersectSuperlayer && ![intersectSuperlayer.delegate respondsToSelector:@selector(contentOffset)]) {
+      
+      // Get parent's tappable area
+      CGRect parentHitRect     = intersectSuperlayer.bounds;
+      BOOL parentClipsToBounds = NO;
+      
+      // If parent is a node, tappable area may be expanded by hitTestSlop
+      ASDisplayNode *parentNode = ASLayerToDisplayNode(intersectSuperlayer);
+      if (parentNode) {
+        UIEdgeInsets parentSlop = [parentNode hitTestSlop];
+        
+        // If parent has hitTestSlop, expand tappable area (if parent doesn't clipToBounds)
+        if (!UIEdgeInsetsEqualToEdgeInsets(UIEdgeInsetsZero, parentSlop)) {
+          parentClipsToBounds = parentNode.clipsToBounds;
+          if (!parentClipsToBounds) {
+            parentHitRect = UIEdgeInsetsInsetRect(parentHitRect, [parentNode hitTestSlop]);
+          }
+        }
+      }
+      
+      // Convert our current rect to parent coordinates
+      CGRect intersectRectInParentCoordinates = [intersectSuperlayer convertRect:intersectRect fromLayer:intersectLayer];
+      
+      // Intersect rect with the parent's tappable area rect
+      intersectRect = CGRectIntersection(parentHitRect, intersectRectInParentCoordinates);
+      if (!CGSizeEqualToSize(parentHitRect.size, intersectRectInParentCoordinates.size)) {
+        clippedEdges = [self setEdgesOfIntersectionForChildRect:intersectRectInParentCoordinates
+                                                     parentRect:parentHitRect rectEdge:clippedEdges];
+        if (parentClipsToBounds) {
+          clipsToBoundsClippedEdges = [self setEdgesOfIntersectionForChildRect:intersectRectInParentCoordinates
+                                                                    parentRect:parentHitRect rectEdge:clipsToBoundsClippedEdges];
+        }
+      }
+      
+      // move up hierarchy
+      intersectLayer      = intersectSuperlayer;
+      intersectSuperlayer = intersectLayer.superlayer;
+    }
+    
+    // produce final overlay image (or fill background if edges aren't restricted)
+    CGRect finalRect   = [intersectLayer convertRect:intersectRect toLayer:layer];
+    UIColor *fillColor = [[UIColor greenColor] colorWithAlphaComponent:0.4];
+    
+    ASImageNode *debugOverlay = [self debugHighlightOverlay];
+    
+    // determine if edges are clipped and if so, highlight the restricted edges
+    if (clippedEdges == UIRectEdgeNone) {
+      debugOverlay.backgroundColor = fillColor;
+    } else {
+      const CGFloat borderWidth = 2.0;
+      UIColor *borderColor      = [[UIColor orangeColor] colorWithAlphaComponent:0.8];
+      UIColor *clipsBorderColor = [UIColor colorWithRed:30/255.0 green:90/255.0 blue:50/255.0 alpha:0.7];
+      CGRect imgRect            = CGRectMake(0, 0, 2.0 * borderWidth + 1.0, 2.0 * borderWidth + 1.0);
+      
+      UIGraphicsBeginImageContext(imgRect.size);
+      
+      [fillColor setFill];
+      UIRectFill(imgRect);
+      
+      [self drawEdgeIfClippedWithEdges:clippedEdges color:clipsBorderColor borderWidth:borderWidth imgRect:imgRect];
+      [self drawEdgeIfClippedWithEdges:clipsToBoundsClippedEdges color:borderColor borderWidth:borderWidth imgRect:imgRect];
+      
+      UIImage *debugHighlightImage = UIGraphicsGetImageFromCurrentImageContext();
+      UIGraphicsEndImageContext();
+      
+      UIEdgeInsets edgeInsets = UIEdgeInsetsMake(borderWidth, borderWidth, borderWidth, borderWidth);
+      debugOverlay.image = [debugHighlightImage resizableImageWithCapInsets:edgeInsets resizingMode:UIImageResizingModeStretch];
+      debugOverlay.backgroundColor = nil;
+    }
+    
+    debugOverlay.frame = finalRect;
+  }
+}
+
+- (UIRectEdge)setEdgesOfIntersectionForChildRect:(CGRect)childRect parentRect:(CGRect)parentRect rectEdge:(UIRectEdge)rectEdge
+{
+  // determine which edges of childRect are outside parentRect (and thus will be clipped)
+  if (childRect.origin.y < parentRect.origin.y) {
+    rectEdge |= UIRectEdgeTop;
+  }
+  if (childRect.origin.x < parentRect.origin.x) {
+    rectEdge |= UIRectEdgeLeft;
+  }
+  if (CGRectGetMaxY(childRect) > CGRectGetMaxY(parentRect)) {
+    rectEdge |= UIRectEdgeBottom;
+  }
+  if (CGRectGetMaxX(childRect) > CGRectGetMaxX(parentRect)) {
+    rectEdge |= UIRectEdgeRight;
+  }
+  
+  return rectEdge;
+}
+
+- (void)drawEdgeIfClippedWithEdges:(UIRectEdge)rectEdge color:(UIColor *)color borderWidth:(CGFloat)borderWidth imgRect:(CGRect)imgRect
+{
+  [color setFill];
+  
+  // highlight individual edges of overlay if edge is restricted by parentRect
+  // so that the developer is aware that increasing hitTestSlop will not result in an expanded tappable area
+  if (rectEdge & UIRectEdgeTop) {
+    UIRectFill(CGRectMake(0.0, 0.0, imgRect.size.width, borderWidth));
+  }
+  if (rectEdge & UIRectEdgeLeft) {
+    UIRectFill(CGRectMake(0.0, 0.0, borderWidth, imgRect.size.height));
+  }
+  if (rectEdge & UIRectEdgeBottom) {
+    UIRectFill(CGRectMake(0.0, imgRect.size.height - borderWidth, imgRect.size.width, borderWidth));
+  }
+  if (rectEdge & UIRectEdgeRight) {
+    UIRectFill(CGRectMake(imgRect.size.width - borderWidth, 0.0, borderWidth, imgRect.size.height));
+  }
+}
+
+@end