[Yoga Beta] Improvements to the experimental support for Yoga layout. (…

…#59)

* [Yoga Beta] Improvements to the experimental support for Yoga layout.

Yoga remains an unsupported / speculative feature, but these improvements are important for
the functionality of clients that are experimenting with it.

For example, without these changes, ASButtonNode is not able to lay out correctly. These
changes allow certain subtrees that use layout specs to coexist properly in a Yoga heirarchy.

The most significant change here is moving ASEdgeInsets into the #if YOGA gating. Although
this is technically an API change, this type was added with no known use cases and is
really only useful for flexbox layout specification. So, before usages of it are created,
it makes sense to constrain the Texture API surface until that time.

* [RTL] Bridge the UISemanticContentAttribute property for more convenient RTL support.

Although apps could handle this before by setting the view's property in didLoad, it's
useful to bridge this property for setting during off-main initialization.

This change also makes RTL fully functional / automatic for Yoga layout users.

* Remove RTL property addition and depend on PR #60 landing first.

* Fix warnings

* Add line to changelog

CHANGELOG.md

@@ -4,3 +4,4 @@
 - Add support for IGListKit post-removal-of-IGListSectionType, in preparation for IGListKit 3.0.0 release. (Adlai-Holler)[https://github.com/Adlai-Holler] (#49)[https://github.com/TextureGroup/Texture/pull/49]
 - Fix `__has_include` check in ASLog.h [Philipp Smorygo]([email protected])
 - Fix potential deadlock in ASControlNode [Garrett Moon](https://github.com/garrettmoon)
+- [Yoga Beta] Improvements to the experimental support for Yoga layout [Scott Goodson](appleguy)

Source/ASDisplayNode+Beta.h

@@ -176,12 +176,14 @@ extern void ASDisplayNodePerformBlockOnEveryYogaChild(ASDisplayNode * _Nullable
 // These methods should not normally be called directly.
 - (void)invalidateCalculatedYogaLayout;
 - (void)calculateLayoutFromYogaRoot:(ASSizeRange)rootConstrainedSize;
+- (void)semanticContentAttributeDidChange:(UISemanticContentAttribute)attribute;
 
 @end
 
 @interface ASLayoutElementStyle (Yoga)
 
-@property (nonatomic, assign, readwrite) ASStackLayoutDirection direction;
+@property (nonatomic, assign, readwrite) ASStackLayoutDirection flexDirection;
+@property (nonatomic, assign, readwrite) YGDirection direction;
 @property (nonatomic, assign, readwrite) CGFloat spacing;
 @property (nonatomic, assign, readwrite) ASStackLayoutJustifyContent justifyContent;
 @property (nonatomic, assign, readwrite) ASStackLayoutAlignItems alignItems;

Source/ASDisplayNode+Yoga.mm

@@ -147,10 +147,15 @@ float yogaDimensionToPercent(ASDimension dimension)
 ASDimension dimensionForEdgeWithEdgeInsets(YGEdge edge, ASEdgeInsets insets)
 {
   switch (edge) {
-    case YGEdgeLeft:   return insets.left;
-    case YGEdgeTop:    return insets.top;
-    case YGEdgeRight:  return insets.right;
-    case YGEdgeBottom: return insets.bottom;
+    case YGEdgeLeft:          return insets.left;
+    case YGEdgeTop:           return insets.top;
+    case YGEdgeRight:         return insets.right;
+    case YGEdgeBottom:        return insets.bottom;
+    case YGEdgeStart:         return insets.start;
+    case YGEdgeEnd:           return insets.end;
+    case YGEdgeHorizontal:    return insets.horizontal;
+    case YGEdgeVertical:      return insets.vertical;
+    case YGEdgeAll:           return insets.all;
     default: ASDisplayNodeCAssert(NO, @"YGEdge other than ASEdgeInsets is not supported.");
       return ASDimensionAuto;
   }
@@ -314,10 +319,9 @@ - (void)setupYogaCalculatedLayout
 
 - (void)setYogaMeasureFuncIfNeeded
 {
-  // Manual size calculation via calculateSizeThatFits:
-  // This will be used for ASTextNode, as well as any other leaf node that has no layout spec.
-  if ((self.methodOverrides & ASDisplayNodeMethodOverrideLayoutSpecThatFits) == NO
-      && self.layoutSpecBlock == NULL &&  self.yogaChildren.count == 0) {
+  // Size calculation via calculateSizeThatFits: or layoutSpecThatFits:
+  // This will be used for ASTextNode, as well as any other node that has no Yoga children
+  if (self.yogaChildren.count == 0) {
     YGNodeRef yogaNode = self.yogaNode; // Use property to assign Ref if needed.
     YGNodeSetContext(yogaNode, (__bridge void *)self);
     YGNodeSetMeasureFunc(yogaNode, &ASLayoutElementYogaMeasureFunc);
@@ -333,8 +337,24 @@ - (void)invalidateCalculatedYogaLayout
   }
 }
 
+- (void)semanticContentAttributeDidChange:(UISemanticContentAttribute)attribute
+{
+  if (AS_AT_LEAST_IOS9) {
+    UIUserInterfaceLayoutDirection layoutDirection =
+                         [UIView userInterfaceLayoutDirectionForSemanticContentAttribute:attribute];
+    self.style.direction = (layoutDirection == UIUserInterfaceLayoutDirectionLeftToRight
+                                             ? YGDirectionLTR : YGDirectionRTL);
+  }
+}
+
 - (void)calculateLayoutFromYogaRoot:(ASSizeRange)rootConstrainedSize
 {
+  if (self.yogaParent) {
+    if (ASHierarchyStateIncludesYogaLayoutMeasuring(self.hierarchyState) == NO) {
+      [self _setNeedsLayoutFromAbove];
+    }
+    return;
+  }
   if (ASHierarchyStateIncludesYogaLayoutMeasuring(self.hierarchyState)) {
     ASDisplayNodeAssert(NO, @"A Yoga layout is being performed by a parent; children must not perform their own until it is done! %@", [self displayNodeRecursiveDescription]);
     return;
@@ -356,14 +376,14 @@ - (void)calculateLayoutFromYogaRoot:(ASSizeRange)rootConstrainedSize
     ASLayoutElementStyle *style = node.style;
     YGNodeRef yogaNode = node.yogaNode;
 
-    YGNodeStyleSetDirection     (yogaNode, YGDirectionInherit);
+    YGNodeStyleSetDirection     (yogaNode, style.direction);
 
     YGNodeStyleSetFlexWrap      (yogaNode, style.flexWrap);
     YGNodeStyleSetFlexGrow      (yogaNode, style.flexGrow);
     YGNodeStyleSetFlexShrink    (yogaNode, style.flexShrink);
     YGNODE_STYLE_SET_DIMENSION  (yogaNode, FlexBasis, style.flexBasis);
 
-    YGNodeStyleSetFlexDirection (yogaNode, yogaFlexDirection(style.direction));
+    YGNodeStyleSetFlexDirection (yogaNode, yogaFlexDirection(style.flexDirection));
     YGNodeStyleSetJustifyContent(yogaNode, yogaJustifyContent(style.justifyContent));
     YGNodeStyleSetAlignSelf     (yogaNode, yogaAlignSelf(style.alignSelf));
     ASStackLayoutAlignItems alignItems = style.alignItems;
@@ -378,12 +398,12 @@ - (void)calculateLayoutFromYogaRoot:(ASSizeRange)rootConstrainedSize
     ASEdgeInsets border   = style.border;
 
     YGEdge edge = YGEdgeLeft;
-    for (int i = 0; i < 4; i++) {
+    for (int i = 0; i < YGEdgeAll + 1; ++i) {
       YGNODE_STYLE_SET_DIMENSION_WITH_EDGE(yogaNode, Position, dimensionForEdgeWithEdgeInsets(edge, position), edge);
       YGNODE_STYLE_SET_DIMENSION_WITH_EDGE(yogaNode, Margin, dimensionForEdgeWithEdgeInsets(edge, margin), edge);
       YGNODE_STYLE_SET_DIMENSION_WITH_EDGE(yogaNode, Padding, dimensionForEdgeWithEdgeInsets(edge, padding), edge);
       YGNODE_STYLE_SET_FLOAT_WITH_EDGE(yogaNode, Border, dimensionForEdgeWithEdgeInsets(edge, border), edge);
-      edge = (edge == YGEdgeLeft ? YGEdgeTop : (edge == YGEdgeTop ? YGEdgeRight : YGEdgeBottom));
+      edge = (YGEdge)(edge + 1);
     }
 
     CGFloat aspectRatio = style.aspectRatio;
@@ -406,7 +426,6 @@ - (void)calculateLayoutFromYogaRoot:(ASSizeRange)rootConstrainedSize
     [node setYogaMeasureFuncIfNeeded];
 
     /* TODO(appleguy): STYLE SETTER METHODS LEFT TO IMPLEMENT
-     void YGNodeStyleSetFlexDirection(YGNodeRef node, YGFlexDirection flexDirection);
      void YGNodeStyleSetOverflow(YGNodeRef node, YGOverflow overflow);
      void YGNodeStyleSetFlex(YGNodeRef node, float flex);
      */

Source/Layout/ASDimension.h

@@ -18,6 +18,7 @@
 #pragma once
 #import <Foundation/Foundation.h>
 #import <CoreGraphics/CoreGraphics.h>
+#import <AsyncDisplayKit/ASAvailability.h>
 #import <AsyncDisplayKit/ASBaseDefines.h>
 #import <AsyncDisplayKit/ASAssert.h>
 
@@ -213,17 +214,6 @@ ASDISPLAYNODE_INLINE AS_WARN_UNUSED_RESULT NSString *NSStringFromASLayoutSize(AS
           NSStringFromASDimension(size.height)];
 }
 
-#pragma mark - ASEdgeInsets
-
-typedef struct {
-  ASDimension top;
-  ASDimension left;
-  ASDimension bottom;
-  ASDimension right;
-} ASEdgeInsets;
-
-extern ASEdgeInsets const ASEdgeInsetsZero;
-
 #pragma mark - ASSizeRange
 
 /**
@@ -308,5 +298,25 @@ ASDISPLAYNODE_INLINE AS_WARN_UNUSED_RESULT BOOL ASSizeRangeEqualToSizeRange(ASSi
  */
 extern AS_WARN_UNUSED_RESULT NSString *NSStringFromASSizeRange(ASSizeRange sizeRange);
 
+#if YOGA
+
+#pragma mark - ASEdgeInsets
+
+typedef struct {
+  ASDimension top;
+  ASDimension left;
+  ASDimension bottom;
+  ASDimension right;
+  ASDimension start;
+  ASDimension end;
+  ASDimension horizontal;
+  ASDimension vertical;
+  ASDimension all;
+} ASEdgeInsets;
+
+extern ASEdgeInsets const ASEdgeInsetsZero;
+
+#endif
+
 NS_ASSUME_NONNULL_END
 ASDISPLAYNODE_EXTERN_C_END

Source/Layout/ASDimension.mm

@@ -67,10 +67,6 @@ ASOVERLOADABLE ASDimension ASDimensionMake(NSString *dimension)
 
 ASLayoutSize const ASLayoutSizeAuto = {ASDimensionAuto, ASDimensionAuto};
 
-#pragma mark - ASEdgeInsets
-
-ASEdgeInsets const ASEdgeInsetsZero = {};
-
 #pragma mark - ASSizeRange
 
 ASSizeRange const ASSizeRangeZero = {};
@@ -115,3 +111,8 @@ ASSizeRange ASSizeRangeIntersect(ASSizeRange sizeRange, ASSizeRange otherSizeRan
           NSStringFromCGSize(sizeRange.min),
           NSStringFromCGSize(sizeRange.max)];
 }
+
+#if YOGA
+#pragma mark - Yoga - ASEdgeInsets
+ASEdgeInsets const ASEdgeInsetsZero = {};
+#endif

Source/Layout/ASLayoutElement.mm

@@ -150,7 +150,8 @@ @implementation ASLayoutElementStyle {
   std::atomic<CGPoint> _layoutPosition;
 
 #if YOGA
-  std::atomic<ASStackLayoutDirection> _direction;
+  std::atomic<ASStackLayoutDirection> _flexDirection;
+  std::atomic<YGDirection> _direction;
   std::atomic<CGFloat> _spacing;
   std::atomic<ASStackLayoutJustifyContent> _justifyContent;
   std::atomic<ASStackLayoutAlignItems> _alignItems;
@@ -600,7 +601,8 @@ - (NSString *)description
 
 #if YOGA
 
-- (ASStackLayoutDirection)direction           { return _direction.load(); }
+- (ASStackLayoutDirection)flexDirection       { return _flexDirection.load(); }
+- (YGDirection)direction                      { return _direction.load(); }
 - (CGFloat)spacing                            { return _spacing.load(); }
 - (ASStackLayoutJustifyContent)justifyContent { return _justifyContent.load(); }
 - (ASStackLayoutAlignItems)alignItems         { return _alignItems.load(); }
@@ -612,7 +614,8 @@ - (ASEdgeInsets)border                        { return _border.load(); }
 - (CGFloat)aspectRatio                        { return _aspectRatio.load(); }
 - (YGWrap)flexWrap                            { return _flexWrap.load(); }
 
-- (void)setDirection:(ASStackLayoutDirection)direction         { _direction.store(direction); }
+- (void)setFlexDirection:(ASStackLayoutDirection)flexDirection { _flexDirection.store(flexDirection); }
+- (void)setDirection:(YGDirection)direction                    { _direction.store(direction); }
 - (void)setSpacing:(CGFloat)spacing                            { _spacing.store(spacing); }
 - (void)setJustifyContent:(ASStackLayoutJustifyContent)justify { _justifyContent.store(justify); }
 - (void)setAlignItems:(ASStackLayoutAlignItems)alignItems      { _alignItems.store(alignItems); }

Source/Private/ASDisplayNode+FrameworkPrivate.h

@@ -221,6 +221,14 @@ __unused static NSString * _Nonnull NSStringFromASHierarchyState(ASHierarchyStat
  */
 - (BOOL)shouldScheduleDisplayWithNewInterfaceState:(ASInterfaceState)newInterfaceState;
 
+/**
+ * @abstract Informs the root node that the intrinsic size of the receiver is no longer valid.
+ *
+ * @discussion The size of a root node is determined by each subnode. Calling invalidateSize will let the root node know
+ * that the intrinsic size of the receiver node is no longer valid and a resizing of the root node needs to happen.
+ */
+- (void)_setNeedsLayoutFromAbove;
+
 /**
  * @abstract Subclass hook for nodes that are acting as root nodes. This method is called if one of the subnodes
  * size is invalidated and may need to result in a different size as the current calculated size.

Source/Private/ASDisplayNode+UIViewBridge.mm

@@ -794,6 +794,9 @@ - (void)setSemanticContentAttribute:(UISemanticContentAttribute)semanticContentA
   _bridge_prologue_write;
   if (AS_AT_LEAST_IOS9) {
     _setToViewOnly(semanticContentAttribute, semanticContentAttribute);
+#if YOGA
+    [self semanticContentAttributeDidChange:semanticContentAttribute];
+#endif
   }
 }