Merge pull request #1687 from levi/constrainedSize

[ASDisplayNode] Move constrained size to ASLayout

Author: appleguy

AsyncDisplayKit/ASDisplayNode.mm

@@ -616,25 +616,20 @@ - (ASLayout *)measureWithSizeRange:(ASSizeRange)constrainedSize
   [self cancelLayoutTransitionsInProgress];
 
   ASLayout *previousLayout = _layout;
-  ASSizeRange previousConstrainedSize = _constrainedSize;
   ASLayout *newLayout = [self calculateLayoutThatFits:constrainedSize];
 
   if (ASHierarchyStateIncludesLayoutPending(_hierarchyState)) {
     _pendingLayoutTransition = [[ASLayoutTransition alloc] initWithNode:self
                                                           pendingLayout:newLayout
-                                                 pendingConstrainedSize:constrainedSize
-                                                         previousLayout:previousLayout
-                                                previousConstrainedSize:previousConstrainedSize];
+                                                         previousLayout:previousLayout];
   } else {
     ASLayoutTransition *layoutContext;
     if (self.usesImplicitHierarchyManagement) {
       layoutContext = [[ASLayoutTransition alloc] initWithNode:self
                                                  pendingLayout:newLayout
-                                        pendingConstrainedSize:constrainedSize
-                                                previousLayout:previousLayout
-                                       previousConstrainedSize:previousConstrainedSize];
+                                                previousLayout:previousLayout];
     }
-    [self applyLayout:newLayout constrainedSize:constrainedSize layoutContext:layoutContext];
+    [self applyLayout:newLayout layoutContext:layoutContext];
     [self _completeLayoutCalculation];
   }
 
@@ -655,10 +650,15 @@ - (BOOL)shouldMeasureWithSizeRange:(ASSizeRange)constrainedSize
     }
   }
 
-  // only calculate the size if
-  //  - we haven't already
-  //  - the constrained size range is different
-  return (!_flags.isMeasured || !ASSizeRangeEqualToSizeRange(constrainedSize, _constrainedSize));
+  // Only generate a new layout if:
+  // - The current layout is dirty
+  // - The passed constrained size is different than the layout's constrained size
+  return ([self _hasDirtyLayout] || !ASSizeRangeEqualToSizeRange(constrainedSize, _layout.constrainedSizeRange));
+}
+
+- (BOOL)_hasDirtyLayout
+{
+  return _layout == nil || _layout.isDirty;
 }
 
 #pragma mark - Layout Transition
@@ -667,9 +667,8 @@ - (void)transitionLayoutWithAnimation:(BOOL)animated
                    shouldMeasureAsync:(BOOL)shouldMeasureAsync
                 measurementCompletion:(void(^)())completion
 {
-  ASSizeRange currentConstrainedSize = _constrainedSize;
   [self invalidateCalculatedLayout];
-  [self transitionLayoutWithSizeRange:currentConstrainedSize
+  [self transitionLayoutWithSizeRange:_layout.constrainedSizeRange
                              animated:animated
                    shouldMeasureAsync:shouldMeasureAsync
                 measurementCompletion:completion];
@@ -732,8 +731,7 @@ - (void)transitionLayoutWithSizeRange:(ASSizeRange)constrainedSize
       }
 
       ASLayout *previousLayout = _layout;
-      ASSizeRange previousConstrainedSize = _constrainedSize;
-      [self applyLayout:newLayout constrainedSize:constrainedSize layoutContext:nil];
+      [self applyLayout:newLayout layoutContext:nil];
 
       ASDisplayNodePerformBlockOnEverySubnode(self, ^(ASDisplayNode * _Nonnull node) {
         [node applyPendingLayoutContext];
@@ -749,9 +747,7 @@ - (void)transitionLayoutWithSizeRange:(ASSizeRange)constrainedSize
 
       _pendingLayoutTransition = [[ASLayoutTransition alloc] initWithNode:self
                                                             pendingLayout:newLayout
-                                                   pendingConstrainedSize:constrainedSize
-                                                           previousLayout:previousLayout
-                                                  previousConstrainedSize:previousConstrainedSize];
+                                                          previousLayout:previousLayout];
       [_pendingLayoutTransition applySubnodeInsertions];
 
       _transitionContext = [[_ASTransitionContext alloc] initWithAnimation:animated
@@ -1028,11 +1024,10 @@ - (void)__setNeedsLayout
   ASDisplayNodeAssertThreadAffinity(self);
   ASDN::MutexLocker l(_propertyLock);
 
-  if (!_flags.isMeasured) {
+  if ([self _hasDirtyLayout]) {
     return;
   }
 
-  ASSizeRange oldConstrainedSize = _constrainedSize;
   [self invalidateCalculatedLayout];
 
   if (_supernode) {
@@ -1045,7 +1040,7 @@ - (void)__setNeedsLayout
   }
 
   // This is the root node. Trigger a full measurement pass on *current* thread. Old constrained size is re-used.
-  [self measureWithSizeRange:oldConstrainedSize];
+  [self measureWithSizeRange:_layout.constrainedSizeRange];
 
   CGRect oldBounds = self.bounds;
   CGSize oldSize = oldBounds.size;
@@ -1105,7 +1100,7 @@ - (void)measureNodeWithBoundsIfNecessary:(CGRect)bounds
   // Normally measure will be called before layout occurs. If this doesn't happen, nothing is going to call it at all.
   // We simply call measureWithSizeRange: using a size range equal to whatever bounds were provided to that element or
   // try to measure the node with the largest size as possible
-  if (self.supernode == nil && !self.supportsRangeManagedInterfaceState && !_flags.isMeasured) {
+  if (self.supernode == nil && !self.supportsRangeManagedInterfaceState && [self _hasDirtyLayout] == NO) {
     if (CGRectEqualToRect(bounds, CGRectZero)) {
       LOG(@"Warning: No size given for node before node was trying to layout itself: %@. Please provide a frame for the node.", self);
     } else {
@@ -1118,7 +1113,7 @@ - (void)layout
 {
   ASDisplayNodeAssertMainThread();
 
-  if (!_flags.isMeasured) {
+  if ([self _hasDirtyLayout]) {
     return;
   }
 
@@ -1956,7 +1951,10 @@ - (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
     // Make sure layoutableObject of the root layout is `self`, so that the flattened layout will be structurally correct.
     if (layout.layoutableObject != self) {
       layout.position = CGPointZero;
-      layout = [ASLayout layoutWithLayoutableObject:self size:layout.size sublayouts:@[layout]];
+      layout = [ASLayout layoutWithLayoutableObject:self
+                               constrainedSizeRange:constrainedSize
+                                               size:layout.size
+                                         sublayouts:@[layout]];
     }
     return [layout flattenedLayoutUsingPredicateBlock:^BOOL(ASLayout *evaluatedLayout) {
       if (self.usesImplicitHierarchyManagement) {
@@ -1969,7 +1967,9 @@ - (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
     // If neither -layoutSpecThatFits: nor -calculateSizeThatFits: is overridden by subclassses, preferredFrameSize should be used,
     // assume that the default implementation of -calculateSizeThatFits: returns it.
     CGSize size = [self calculateSizeThatFits:constrainedSize.max];
-    return [ASLayout layoutWithLayoutableObject:self size:ASSizeRangeClamp(constrainedSize, size)];
+    return [ASLayout layoutWithLayoutableObject:self
+                           constrainedSizeRange:constrainedSize
+                                           size:ASSizeRangeClamp(constrainedSize, size)];
   }
 }
 
@@ -2009,7 +2009,7 @@ - (CGSize)calculatedSize
 - (ASSizeRange)constrainedSizeForCalculatedLayout
 {
   ASDN::MutexLocker l(_propertyLock);
-  return _constrainedSize;
+  return _layout.constrainedSizeRange;
 }
 
 - (void)setLayoutSpecBlock:(ASLayoutSpecBlock)layoutSpecBlock
@@ -2063,8 +2063,10 @@ - (UIImage *)placeholderImage
 - (void)invalidateCalculatedLayout
 {
   ASDN::MutexLocker l(_propertyLock);
-  // This will cause -measureWithSizeRange: to actually compute the size instead of returning the previously cached size
-  _flags.isMeasured = NO;
+
+  // This will cause the next call to -measureWithSizeRange: to actually compute a new layout
+  // instead of returning the current layout
+  _layout.dirty = YES;
 }
 
 - (void)__didLoad
@@ -2395,26 +2397,19 @@ - (void)applyPendingLayoutContext
 {
   ASDN::MutexLocker l(_propertyLock);
   if (_pendingLayoutTransition) {
-    [self applyLayout:_pendingLayoutTransition.pendingLayout
-      constrainedSize:_pendingLayoutTransition.pendingConstrainedSize
-        layoutContext:_pendingLayoutTransition];
+    [self applyLayout:_pendingLayoutTransition.pendingLayout layoutContext:_pendingLayoutTransition];
     _pendingLayoutTransition = nil;
   }
 }
 
-- (void)applyLayout:(ASLayout *)layout
-    constrainedSize:(ASSizeRange)constrainedSize
-      layoutContext:(ASLayoutTransition *)layoutContext
+- (void)applyLayout:(ASLayout *)layout layoutContext:(ASLayoutTransition *)layoutContext
 {
   ASDN::MutexLocker l(_propertyLock);
   _layout = layout;
 
   ASDisplayNodeAssertTrue(layout.layoutableObject == self);
   ASDisplayNodeAssertTrue(layout.size.width >= 0.0);
   ASDisplayNodeAssertTrue(layout.size.height >= 0.0);
-
-  _constrainedSize = constrainedSize;
-  _flags.isMeasured = YES;
 
   if (self.usesImplicitHierarchyManagement && layoutContext != nil) {
     [layoutContext applySubnodeInsertions];

AsyncDisplayKit/Layout/ASBackgroundLayoutSpec.mm

@@ -55,7 +55,10 @@ - (ASLayout *)measureWithSizeRange:(ASSizeRange)constrainedSize
   contentsLayout.position = CGPointZero;
   [sublayouts addObject:contentsLayout];
 
-  return [ASLayout layoutWithLayoutableObject:self size:contentsLayout.size sublayouts:sublayouts];
+  return [ASLayout layoutWithLayoutableObject:self
+                         constrainedSizeRange:constrainedSize
+                                         size:contentsLayout.size
+                                   sublayouts:sublayouts];
 }
 
 - (void)setBackground:(id<ASLayoutable>)background

AsyncDisplayKit/Layout/ASInsetLayoutSpec.mm

@@ -91,7 +91,9 @@ - (ASLayout *)measureWithSizeRange:(ASSizeRange)constrainedSize
 
   if (self.child == nil) {
     ASDisplayNodeAssert(NO, @"Inset spec measured without a child. The spec will do nothing.");
-    return [ASLayout layoutWithLayoutableObject:self size:CGSizeZero];
+    return [ASLayout layoutWithLayoutableObject:self
+                           constrainedSizeRange:constrainedSize
+                                           size:CGSizeZero];
   }
 
   ASLayout *sublayout = [self.child measureWithSizeRange:insetConstrainedSize];
@@ -112,7 +114,10 @@ - (ASLayout *)measureWithSizeRange:(ASSizeRange)constrainedSize
 
   sublayout.position = CGPointMake(x, y);
 
-  return [ASLayout layoutWithLayoutableObject:self size:computedSize sublayouts:@[sublayout]];
+  return [ASLayout layoutWithLayoutableObject:self
+                         constrainedSizeRange:constrainedSize
+                                         size:computedSize
+                                   sublayouts:@[sublayout]];
 }
 
 @end

AsyncDisplayKit/Layout/ASLayout.h

@@ -13,14 +13,17 @@
 #import <UIKit/UIKit.h>
 #import <AsyncDisplayKit/ASAssert.h>
 #import <AsyncDisplayKit/ASLayoutable.h>
+#import <AsyncDisplayKit/ASDimension.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
 extern CGPoint const CGPointNull;
 
 extern BOOL CGPointIsNull(CGPoint point);
 
-/** Represents a computed immutable layout tree. */
+/**
+ * A node in the layout tree that represents the size and position of the object that created it (ASLayoutable).
+ */
 @interface ASLayout : NSObject
 
 /**
@@ -40,6 +43,11 @@ extern BOOL CGPointIsNull(CGPoint point);
  */
 @property (nonatomic, readwrite) CGPoint position;
 
+/**
+ * The size range that was use to determine the size of the layout.
+ */
+@property (nonatomic, readonly) ASSizeRange constrainedSizeRange;
+
 /**
  * Array of ASLayouts. Each must have a valid non-null position.
  */
@@ -50,6 +58,11 @@ extern BOOL CGPointIsNull(CGPoint point);
  */
 @property (nonatomic, readonly) NSArray<ASLayout *> *immediateSublayouts;
 
+/**
+ * Mark the layout dirty for future regeneration.
+ */
+@property (nonatomic, getter=isDirty) BOOL dirty;
+
 /**
  * A boolean describing if the current layout has been flattened.
  */
@@ -67,6 +80,7 @@ extern BOOL CGPointIsNull(CGPoint point);
  * @param sublayouts Sublayouts belong to the new layout.
  */
 + (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
+                      constrainedSizeRange:(ASSizeRange)sizeRange
                                       size:(CGSize)size
                                   position:(CGPoint)position
                                 sublayouts:(nullable NSArray<ASLayout *> *)sublayouts
@@ -85,6 +99,7 @@ extern BOOL CGPointIsNull(CGPoint point);
  * @param sublayouts Sublayouts belong to the new layout.
  */
 + (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
+                      constrainedSizeRange:(ASSizeRange)sizeRange
                                       size:(CGSize)size
                                 sublayouts:(nullable NSArray<ASLayout *> *)sublayouts;
 
@@ -97,7 +112,9 @@ extern BOOL CGPointIsNull(CGPoint point);
  *
  * @param size The size of this layout.
  */
-+ (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject size:(CGSize)size;
++ (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
+                      constrainedSizeRange:(ASSizeRange)sizeRange
+                                      size:(CGSize)size;
 
 /**
  * Convenience initializer that is flattened and has CGPointNull position.
@@ -109,6 +126,7 @@ extern BOOL CGPointIsNull(CGPoint point);
  * @param sublayouts Sublayouts belong to the new layout.
  */
 + (instancetype)flattenedLayoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
+                               constrainedSizeRange:(ASSizeRange)sizeRange
                                                size:(CGSize)size
                                          sublayouts:(nullable NSArray<ASLayout *> *)sublayouts;
 

AsyncDisplayKit/Layout/ASLayout.mm

@@ -12,6 +12,7 @@
 #import "ASAssert.h"
 #import "ASLayoutSpecUtilities.h"
 #import "ASInternalHelpers.h"
+#import "ASDimension.h"
 #import <queue>
 
 CGPoint const CGPointNull = {NAN, NAN};
@@ -24,6 +25,7 @@ extern BOOL CGPointIsNull(CGPoint point)
 @implementation ASLayout
 
 + (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
+                      constrainedSizeRange:(ASSizeRange)sizeRange
                                       size:(CGSize)size
                                   position:(CGPoint)position
                                 sublayouts:(NSArray *)sublayouts
@@ -46,7 +48,9 @@ + (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
     } else {
       size = CGSizeMake(ASCeilPixelValue(size.width), ASCeilPixelValue(size.height));
     }
+    l->_constrainedSizeRange = sizeRange;
     l->_size = size;
+    l->_dirty = NO;
 
     if (CGPointIsNull(position) == NO) {
       l->_position = CGPointMake(ASCeilPixelValue(position.x), ASCeilPixelValue(position.y));
@@ -68,22 +72,39 @@ + (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
 }
 
 + (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
+                      constrainedSizeRange:(ASSizeRange)sizeRange
                                       size:(CGSize)size
                                 sublayouts:(NSArray *)sublayouts
 {
-  return [self layoutWithLayoutableObject:layoutableObject size:size position:CGPointNull sublayouts:sublayouts flattened:NO];
+  return [self layoutWithLayoutableObject:layoutableObject
+                     constrainedSizeRange:sizeRange
+                                     size:size
+                                 position:CGPointNull
+                               sublayouts:sublayouts
+                                flattened:NO];
 }
 
-+ (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject size:(CGSize)size
++ (instancetype)layoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
+                      constrainedSizeRange:(ASSizeRange)sizeRange
+                                      size:(CGSize)size
 {
-  return [self layoutWithLayoutableObject:layoutableObject size:size sublayouts:nil];
+  return [self layoutWithLayoutableObject:layoutableObject
+                     constrainedSizeRange:sizeRange
+                                     size:size
+                               sublayouts:nil];
 }
 
 + (instancetype)flattenedLayoutWithLayoutableObject:(id<ASLayoutable>)layoutableObject
+                               constrainedSizeRange:(ASSizeRange)sizeRange
                                                size:(CGSize)size
                                          sublayouts:(nullable NSArray<ASLayout *> *)sublayouts
 {
-  return [self layoutWithLayoutableObject:layoutableObject size:size position:CGPointNull sublayouts:sublayouts flattened:YES];
+  return [self layoutWithLayoutableObject:layoutableObject
+                     constrainedSizeRange:sizeRange
+                                     size:size
+                                 position:CGPointNull
+                               sublayouts:sublayouts
+                                flattened:YES];
 }
 
 - (ASLayout *)flattenedLayoutUsingPredicateBlock:(BOOL (^)(ASLayout *))predicateBlock
@@ -110,6 +131,7 @@ - (ASLayout *)flattenedLayoutUsingPredicateBlock:(BOOL (^)(ASLayout *))predicate
 
       if (predicateBlock(context.layout)) {
         [flattenedSublayouts addObject:[ASLayout layoutWithLayoutableObject:context.layout.layoutableObject
+                                                       constrainedSizeRange:context.layout.constrainedSizeRange
                                                                        size:context.layout.size
                                                                    position:context.absolutePosition
                                                                  sublayouts:nil
@@ -124,7 +146,10 @@ - (ASLayout *)flattenedLayoutUsingPredicateBlock:(BOOL (^)(ASLayout *))predicate
     }
   }
 
-  return [ASLayout flattenedLayoutWithLayoutableObject:_layoutableObject size:_size sublayouts:flattenedSublayouts];
+  return [ASLayout flattenedLayoutWithLayoutableObject:_layoutableObject
+                                  constrainedSizeRange:_constrainedSizeRange
+                                                  size:_size
+                                            sublayouts:flattenedSublayouts];
 }
 
 - (CGRect)frame