Use Native convertRect:, convertPoint: Methods to Handle Nil Cases (#2889)

* When converting rects, points on loaded nodes, call into UIKit/CoreAnimation

* Always use view-ish behavior

* Improve nil window handling, add documentation

Author: Adlai Holler

AsyncDisplayKit/ASDisplayNode.mm

@@ -1805,6 +1805,21 @@ static inline CATransform3D _calculateTransformFromReferenceToTarget(ASDisplayNo
 - (CGPoint)convertPoint:(CGPoint)point fromNode:(ASDisplayNode *)node
 {
   ASDisplayNodeAssertThreadAffinity(self);
+  
+  /**
+   * When passed node=nil, all methods in this family use the UIView-style
+   * behavior – that is, convert from/to window coordinates if there's a window,
+   * otherwise return the point untransformed.
+   */
+  if (node == nil && self.nodeLoaded) {
+    CALayer *layer = self.layer;
+    if (UIWindow *window = ASFindWindowOfLayer(layer)) {
+      return [layer convertPoint:point fromLayer:window.layer];
+    } else {
+      return point;
+    }
+  }
+  
   // Get root node of the accessible node hierarchy, if node not specified
   node = node ? : ASDisplayNodeUltimateParentOfNode(self);
 
@@ -1820,6 +1835,16 @@ - (CGPoint)convertPoint:(CGPoint)point fromNode:(ASDisplayNode *)node
 - (CGPoint)convertPoint:(CGPoint)point toNode:(ASDisplayNode *)node
 {
   ASDisplayNodeAssertThreadAffinity(self);
+  
+  if (node == nil && self.nodeLoaded) {
+    CALayer *layer = self.layer;
+    if (UIWindow *window = ASFindWindowOfLayer(layer)) {
+      return [layer convertPoint:point toLayer:window.layer];
+    } else {
+      return point;
+    }
+  }
+  
   // Get root node of the accessible node hierarchy, if node not specified
   node = node ? : ASDisplayNodeUltimateParentOfNode(self);
 
@@ -1835,6 +1860,16 @@ - (CGPoint)convertPoint:(CGPoint)point toNode:(ASDisplayNode *)node
 - (CGRect)convertRect:(CGRect)rect fromNode:(ASDisplayNode *)node
 {
   ASDisplayNodeAssertThreadAffinity(self);
+  
+  if (node == nil && self.nodeLoaded) {
+    CALayer *layer = self.layer;
+    if (UIWindow *window = ASFindWindowOfLayer(layer)) {
+      return [layer convertRect:rect fromLayer:window.layer];
+    } else {
+      return rect;
+    }
+  }
+  
   // Get root node of the accessible node hierarchy, if node not specified
   node = node ? : ASDisplayNodeUltimateParentOfNode(self);
 
@@ -1850,6 +1885,16 @@ - (CGRect)convertRect:(CGRect)rect fromNode:(ASDisplayNode *)node
 - (CGRect)convertRect:(CGRect)rect toNode:(ASDisplayNode *)node
 {
   ASDisplayNodeAssertThreadAffinity(self);
+  
+  if (node == nil && self.nodeLoaded) {
+    CALayer *layer = self.layer;
+    if (UIWindow *window = ASFindWindowOfLayer(layer)) {
+      return [layer convertRect:rect toLayer:window.layer];
+    } else {
+      return rect;
+    }
+  }
+  
   // Get root node of the accessible node hierarchy, if node not specified
   node = node ? : ASDisplayNodeUltimateParentOfNode(self);
 

AsyncDisplayKit/ASDisplayNodeExtras.h

@@ -125,6 +125,11 @@ extern ASDisplayNode * _Nullable ASDisplayNodeFindFirstSupernode(ASDisplayNode *
  */
 extern __kindof ASDisplayNode * _Nullable ASDisplayNodeFindFirstSupernodeOfClass(ASDisplayNode *start, Class c) AS_WARN_UNUSED_RESULT;
 
+/**
+ * Given a layer, find the window it lives in, if any.
+ */
+extern UIWindow * _Nullable ASFindWindowOfLayer(CALayer *layer) AS_WARN_UNUSED_RESULT;
+
 /**
  * Given two nodes, finds their most immediate common parent.  Used for geometry conversion methods.
  * NOTE: It is an error to try to convert between nodes which do not share a common ancestor. This behavior is

AsyncDisplayKit/ASDisplayNodeExtras.mm

@@ -249,6 +249,21 @@ static inline BOOL _ASDisplayNodeIsAncestorOfDisplayNode(ASDisplayNode *possible
   return NO;
 }
 
+extern UIWindow * _Nullable ASFindWindowOfLayer(CALayer *layer)
+{
+  while (layer != nil) {
+    if (UIView *view = ASDynamicCast(layer.delegate, UIView)) {
+      if ([view isKindOfClass:[UIWindow class]]) {
+        return (UIWindow *)view;
+      } else {
+        return view.window;
+      }
+    }
+    layer = layer.superlayer;
+  }
+  return nil;
+}
+
 extern ASDisplayNode *ASDisplayNodeFindClosestCommonAncestor(ASDisplayNode *node1, ASDisplayNode *node2)
 {
   ASDisplayNode *possibleAncestor = node1;

AsyncDisplayKitTests/ASDisplayNodeTests.m

@@ -2278,4 +2278,25 @@ - (void)testThatBackgroundLayoutSpecOrdersSubnodesCorrectly
   XCTAssertLessThan(underlayIndex, overlayIndex);
 }
 
+- (void)testThatConvertPointGoesToWindowWhenPassedNil
+{
+  UIWindow *window = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];
+  ASDisplayNode *node = [[ASDisplayNode alloc] init];
+  node.frame = CGRectMake(10, 10, 10, 10);
+  [window addSubnode:node];
+  CGPoint expectedOrigin = CGPointMake(10, 10);
+  ASXCTAssertEqualPoints([node convertPoint:node.bounds.origin toNode:nil], expectedOrigin);
+}
+
+- (void)testThatConvertPointGoesToWindowWhenPassedNil_layerBacked
+{
+  UIWindow *window = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];
+  ASDisplayNode *node = [[ASDisplayNode alloc] init];
+  node.layerBacked = YES;
+  node.frame = CGRectMake(10, 10, 10, 10);
+  [window addSubnode:node];
+  CGPoint expectedOrigin = CGPointMake(10, 10);
+  ASXCTAssertEqualPoints([node convertPoint:node.bounds.origin toNode:nil], expectedOrigin);
+}
+
 @end

Base/ASBaseDefines.h

@@ -184,4 +184,7 @@
 #define ASOVERLOADABLE __attribute__((overloadable))
 
 /// Ensure that class is of certain kind
-#define ASDynamicCast(x, c) ((c *) ([x isKindOfClass:[c class]] ? x : nil))
+#define ASDynamicCast(x, c) ({ \
+  id __val = x;\
+  ((c *) ([__val isKindOfClass:[c class]] ? __val : nil));\
+})