Improve UIAccessiblityContainer / -accessibilityElements override support

Schemas/configuration.json

@@ -25,7 +25,8 @@
                     "exp_dispatch_apply",
                     "exp_oom_bg_dealloc_disable",
                     "exp_transaction_operation_retain_cycle",
-                    "exp_remove_textkit_initialising_lock"
+                    "exp_text_node_2_a11y_container",
+                    "exp_expose_text_links_a11y"
                 ]
     		}
 		}

Source/ASDisplayNode+Beta.h

@@ -84,9 +84,13 @@ typedef struct {
 @property (readonly) ASDisplayNodePerformanceMeasurements performanceMeasurements;
 
 /**
- * @abstract Whether this node acts as an accessibility container. If set to YES, then this node's accessibility label will represent
- * an aggregation of all child nodes' accessibility labels. Nodes in this node's subtree that are also accessibility containers will
- * not be included in this aggregation, and will be exposed as separate accessibility elements to UIKit.
+ * @abstract Whether this node acts as an accessibility container. If set to YES, then this node's
+ * accessibility label will represent an aggregation of all child nodes' accessibility labels and
+ * this node's accessibility custom actions will be represented will be the aggregation of all
+ * child nodes that have a accessibility trait of UIAccessibilityTraitLink,
+ * UIAccessibilityTraitKeyboardKey or UIAccessibilityTraitButton.
+ * Nodes in this node's subtree that are also accessibility containers will not be included in this
+ * aggregation, and will be exposed as separate accessibility elements to UIKit.
  */
 @property BOOL isAccessibilityContainer;
 

Source/ASExperimentalFeatures.h

@@ -27,10 +27,11 @@ typedef NS_OPTIONS(NSUInteger, ASExperimentalFeatures) {
   ASExperimentalSkipClearData = 1 << 6,                     // exp_skip_clear_data
   ASExperimentalDidEnterPreloadSkipASMLayout = 1 << 7,      // exp_did_enter_preload_skip_asm_layout
   ASExperimentalDispatchApply = 1 << 8,                     // exp_dispatch_apply
-  ASExperimentalOOMBackgroundDeallocDisable = 1 << 9,      // exp_oom_bg_dealloc_disable
+  ASExperimentalOOMBackgroundDeallocDisable = 1 << 9,       // exp_oom_bg_dealloc_disable
   ASExperimentalTransactionOperationRetainCycle = 1 << 10,  // exp_transaction_operation_retain_cycle
   ASExperimentalRemoveTextKitInitialisingLock = 1 << 11,    // exp_remove_textkit_initialising_lock
   ASExperimentalDrawingGlobal = 1 << 12,                    // exp_drawing_global
+  ASExperimentalExposeTextLinksForA11Y = 1 << 13,           // exp_expose_text_links_a11y
   ASExperimentalFeatureAll = 0xFFFFFFFF
 };
 

Source/ASExperimentalFeatures.mm

@@ -24,7 +24,9 @@
                                       @"exp_oom_bg_dealloc_disable",
                                       @"exp_transaction_operation_retain_cycle",
                                       @"exp_remove_textkit_initialising_lock",
-                                      @"exp_drawing_global"]));
+                                      @"exp_drawing_global",
+                                      @"exp_text_node_2_a11y_container",
+                                      @"exp_expose_text_links_a11y"]));
   if (flags == ASExperimentalFeatureAll) {
     return allNames;
   }

Source/ASTextNode2.mm

@@ -30,6 +30,23 @@
 #import <AsyncDisplayKit/ASTextLayout.h>
 #import <AsyncDisplayKit/ASThread.h>
 
+@interface ASTextNodeAccessiblityElement : UIAccessibilityElement
+@property (assign) NSRange accessibilityRange;
+@end
+
+@implementation ASTextNodeAccessiblityElement
+
+- (instancetype)initWithAccessibilityContainer:(id)container
+{
+  self = [super initWithAccessibilityContainer:container];
+  if (self) {
+    _accessibilityRange = NSMakeRange(NSNotFound, 0);
+  }
+  return self;
+}
+
+@end
+
 @interface ASTextCacheValue : NSObject {
   @package
   AS::Mutex _m;
@@ -215,9 +232,9 @@ - (instancetype)init
     self.linkAttributeNames = DefaultLinkAttributeNames();
 
     // Accessibility
-    self.isAccessibilityElement = YES;
+    self.isAccessibilityElement = !ASActivateExperimentalFeature(ASExperimentalTextNode2A11YContainer);
     self.accessibilityTraits = self.defaultAccessibilityTraits;
-    
+
     // Placeholders
     // Disabled by default in ASDisplayNode, but add a few options for those who toggle
     // on the special placeholder behavior of ASTextNode.
@@ -315,6 +332,142 @@ - (UIAccessibilityTraits)defaultAccessibilityTraits
   return UIAccessibilityTraitStaticText;
 }
 
+/// Uses the given layout, node and container node to calculate the accessibiliyty frame for the given ASTextNodeAccessiblityElement in screen coordinates.
+static void ASUpdateAccessibilityFrame(ASTextNodeAccessiblityElement *accessibilityElement, ASTextLayout *layout, ASDisplayNode * _Nullable containerNode, ASDisplayNode *node) {
+  containerNode = containerNode ?:  ASFirstNonLayerBackedSupernodeForNode(node);
+  CGRect textLayoutFrame = CGRectZero;
+  if (accessibilityElement.accessibilityRange.location == NSNotFound) {
+    // If no accessibilityRange was specified (as is done for the text element), just use the
+    // label's range and clampt to the visible range otherwise the returned rect would be invalid.
+    NSRange range = NSMakeRange(0, accessibilityElement.accessibilityLabel.length);
+    range = NSIntersectionRange(range, layout.visibleRange);
+    textLayoutFrame = [layout rectForRange:[ASTextRange rangeWithRange:range]];
+  } else {
+    textLayoutFrame = [layout rectForRange:[ASTextRange rangeWithRange:accessibilityElement.accessibilityRange]];
+  }
+  CGRect accessibilityFrame = [node convertRect:textLayoutFrame toNode:containerNode];
+  accessibilityElement.accessibilityFrame = UIAccessibilityConvertFrameToScreenCoordinates(accessibilityFrame, containerNode.view);
+}
+
+/// Walks up the node tree and searches for the first node that is not layer backed
+static ASDisplayNode *ASFirstNonLayerBackedSupernodeForNode(ASDisplayNode *node) {
+  ASDisplayNode *containerNode = node;
+  while (containerNode.isLayerBacked) {
+    containerNode = containerNode.supernode;
+  }
+  return containerNode;
+}
+
+- (NSInteger)accessibilityElementCount
+{
+  if (
+      !ASActivateExperimentalFeature(ASExperimentalTextNode2A11YContainer)) {
+    return [super accessibilityElementCount];
+  }
+
+  return self.accessibilityElements.count;
+}
+
+/// Overwrite accessibilityElementAtIndex: so we can update the element's accessibilityFrame when it is requested.
+- (id)accessibilityElementAtIndex:(NSInteger)index
+{
+  if (!ASActivateExperimentalFeature(ASExperimentalTextNode2A11YContainer)) {
+    return [super accessibilityElementAtIndex:index];
+  }
+
+  ASTextNodeAccessiblityElement *accessibilityElement = self.accessibilityElements[index];
+
+  ASTextLayout *layout = ASTextNodeCompatibleLayoutWithContainerAndText(_textContainer, _attributedText);
+  ASUpdateAccessibilityFrame(accessibilityElement, layout, nil, self);
+  return accessibilityElement;
+}
+
+- (NSArray *)accessibilityElements
+{
+  if (!ASActivateExperimentalFeature(ASExperimentalTextNode2A11YContainer)) {
+    return [super accessibilityElements];
+  }
+
+  if (_accessibilityElements != nil) {
+    return _accessibilityElements;
+  }
+
+  NSAttributedString *attributedText = _attributedText;
+  NSInteger attributedTextLength = attributedText.length;
+  if (attributedTextLength == 0) {
+    _accessibilityElements = @[];
+    return _accessibilityElements;
+  }
+
+  NSMutableArray<ASTextNodeAccessiblityElement *> *accessibilityElements = [[NSMutableArray alloc] init];
+
+  // Search the first node that is not layer backed
+  ASDisplayNode *containerNode = ASFirstNonLayerBackedSupernodeForNode(self);
+  ASTextLayout *layout = ASTextNodeCompatibleLayoutWithContainerAndText(_textContainer, attributedText);
+
+  // Create an accessibility element to represent the label's text. It's not necessary to specify
+  // a accessibilityRange here, as the entirety of the text is being represented.
+  ASTextNodeAccessiblityElement *accessibilityElement = [[ASTextNodeAccessiblityElement alloc] initWithAccessibilityContainer:containerNode.view];
+  accessibilityElement.accessibilityIdentifier = self.accessibilityIdentifier;
+  accessibilityElement.accessibilityLabel = self.accessibilityLabel;
+  accessibilityElement.accessibilityHint = self.accessibilityHint;
+  accessibilityElement.accessibilityValue = self.accessibilityValue;
+  accessibilityElement.accessibilityTraits = self.accessibilityTraits;
+  if (AS_AVAILABLE_IOS_TVOS(11, 11)) {
+    accessibilityElement.accessibilityAttributedLabel = self.accessibilityAttributedLabel;
+    accessibilityElement.accessibilityAttributedHint = self.accessibilityAttributedHint;
+    accessibilityElement.accessibilityAttributedValue = self.accessibilityAttributedValue;
+  }
+  ASUpdateAccessibilityFrame(accessibilityElement, layout, containerNode, self);
+  [accessibilityElements addObject:accessibilityElement];
+
+  if (ASActivateExperimentalFeature(ASExperimentalExposeTextLinksForA11Y)) {
+    // Collect all links as accessiblity items
+    for (NSString *linkAttributeName in _linkAttributeNames) {
+      [attributedText enumerateAttribute:linkAttributeName inRange:NSMakeRange(0, attributedTextLength) options:NSAttributedStringEnumerationLongestEffectiveRangeNotRequired usingBlock:^(id  _Nullable value, NSRange range, BOOL * _Nonnull stop) {
+        if (value == nil) {
+          return;
+        }
+
+        ASTextNodeAccessiblityElement *accessibilityElement = [[ASTextNodeAccessiblityElement alloc] initWithAccessibilityContainer:self];
+        accessibilityElement.accessibilityTraits = UIAccessibilityTraitLink;;
+        accessibilityElement.accessibilityLabel = [attributedText.string substringWithRange:range];
+        accessibilityElement.accessibilityRange = range;
+        if (AS_AVAILABLE_IOS_TVOS(11, 11)) {
+          accessibilityElement.accessibilityAttributedLabel = [attributedText attributedSubstringFromRange:range];
+        }
+        ASUpdateAccessibilityFrame(accessibilityElement, layout, containerNode, self);
+        [accessibilityElements addObject:accessibilityElement];
+      }];
+    }
+  }
+  _accessibilityElements = accessibilityElements;
+  return _accessibilityElements;
+}
+
+- (void)setIsAccessibilityElement:(BOOL)isAccessibilityElement
+{
+  if (ASActivateExperimentalFeature(ASExperimentalTextNode2A11YContainer)) {
+    // Instead of relying on labels accessibility, We implement UIAccessibilityContainer and
+    // handle accessibility with ASTextNode2
+    return;
+  }
+
+  [super setIsAccessibilityElement:isAccessibilityElement];
+
+}
+
+- (BOOL)isAccessibilityElement {
+  if (ASActivateExperimentalFeature(ASExperimentalTextNode2A11YContainer)) {
+    // Instead of relying on labels accessibility, We implement UIAccessibilityContainer and
+    // handle accessibility with ASTextNode2
+    return NO;
+  }
+
+  // Use whatever the default is
+  return [super isAccessibilityElement];
+}
+
 #pragma mark - Layout and Sizing
 
 - (void)setTextContainerInset:(UIEdgeInsets)textContainerInset
@@ -414,20 +567,22 @@ - (void)setAttributedText:(NSAttributedString *)attributedText
     style.ascender = [[self class] ascenderWithAttributedString:attributedText];
     style.descender = [[attributedText attribute:NSFontAttributeName atIndex:attributedText.length - 1 effectiveRange:NULL] descender];
   }
-  
+
   // Tell the display node superclasses that the cached layout is incorrect now
   [self setNeedsLayout];
-  
+
   // Force display to create renderer with new size and redisplay with new string
   [self setNeedsDisplay];
 
   // Accessiblity
   self.accessibilityLabel = self.defaultAccessibilityLabel;
-
-  // We update the isAccessibilityElement setting if this node is not switching between strings.
-  if (oldAttributedText.length == 0 || length == 0) {
-    // We're an accessibility element by default if there is a string.
-    self.isAccessibilityElement = (length != 0);
+
+  if (!ASActivateExperimentalFeature(ASExperimentalTextNode2A11YContainer)) {
+    // We update the isAccessibilityElement setting if this node is not switching between strings.
+    if (oldAttributedText.length == 0 || length == 0) {
+      // We're an accessibility element by default if there is a string.
+      self.isAccessibilityElement = (length != 0);
+    }
   }
 
 #if AS_TEXTNODE2_RECORD_ATTRIBUTED_STRINGS

Source/Details/_ASDisplayView.mm

@@ -44,7 +44,7 @@ @implementation _ASDisplayView
   } _internalFlags;
 
   NSArray *_accessibilityElements;
-  CGRect _lastAccessibilityElementsFrame;
+  _ASDisplayViewAccessibilityFlags _accessibilityFlags;
 }
 
 #pragma mark - Class

Source/Details/_ASDisplayViewAccessiblity.h

@@ -14,3 +14,10 @@
 // should still work as long as accessibility is enabled, this framework provides no guarantees on
 // their correctness. For details, see
 // https://developer.apple.com/documentation/objectivec/nsobject/1615147-accessibilityelements
+
+struct _ASDisplayViewAccessibilityFlags {
+  unsigned inAccessibilityElementCount:1;
+  unsigned inIndexOfAccessibilityElement:1;
+  unsigned inAccessibilityElementAtIndex:1;
+  unsigned inSetAccessibilityElements:1;
+};