[ASStackLayoutSpec] Refactor baseline alignment algorithm (#2892)

* Add tests for baseline alignments

* Merge baseline alignment algorithm to the main stack algorithm
- Baseline alignment is now part of the main stack algorithm.
- ASStackBaselinePositionedLayout is no longer needed and removed.

* All snapshot test cases of ASStackLayoutSpec are passing now

* Remove baselineRelativeArrangement

* Remove TODO

* Minor fixes in cross size determination step

Author: nguyenhuy

AsyncDisplayKit.xcodeproj/project.pbxproj

@@ -297,9 +297,6 @@
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-		9C8221961BA237B80037F19A /* ASStackBaselinePositionedLayout.h in Headers */ = {isa = PBXBuildFile; fileRef = 9C8221931BA237B80037F19A /* ASStackBaselinePositionedLayout.h */; };
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-		9C8221981BA237B80037F19A /* ASStackBaselinePositionedLayout.mm in Sources */ = {isa = PBXBuildFile; fileRef = 9C8221941BA237B80037F19A /* ASStackBaselinePositionedLayout.mm */; };
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@@ -640,7 +637,6 @@
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-		F7CE6C9D1D2CDB5800BE4C15 /* ASStackBaselinePositionedLayout.h in CopyFiles */ = {isa = PBXBuildFile; fileRef = 9C8221931BA237B80037F19A /* ASStackBaselinePositionedLayout.h */; };
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@@ -818,7 +814,6 @@
 				F7CE6C991D2CDB5800BE4C15 /* ASLayoutSpecUtilities.h in CopyFiles */,
 				F7CE6C9A1D2CDB5800BE4C15 /* ASMultidimensionalArrayUtils.h in CopyFiles */,
 				F7CE6C9B1D2CDB5800BE4C15 /* ASPendingStateController.h in CopyFiles */,
-				F7CE6C9D1D2CDB5800BE4C15 /* ASStackBaselinePositionedLayout.h in CopyFiles */,
 				F7CE6C9E1D2CDB5800BE4C15 /* ASStackLayoutSpecUtilities.h in CopyFiles */,
 				F7CE6C9F1D2CDB5800BE4C15 /* ASStackPositionedLayout.h in CopyFiles */,
 				F7CE6CA01D2CDB5800BE4C15 /* ASStackUnpositionedLayout.h in CopyFiles */,
@@ -1072,8 +1067,6 @@
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-		9C8221931BA237B80037F19A /* ASStackBaselinePositionedLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASStackBaselinePositionedLayout.h; sourceTree = "<group>"; };
-		9C8221941BA237B80037F19A /* ASStackBaselinePositionedLayout.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASStackBaselinePositionedLayout.mm; sourceTree = "<group>"; };
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@@ -1638,8 +1631,6 @@
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 				CC3B20811C3F76D600798563 /* ASPendingStateController.h */,
 				CC3B20821C3F76D600798563 /* ASPendingStateController.mm */,
-				9C8221931BA237B80037F19A /* ASStackBaselinePositionedLayout.h */,
-				9C8221941BA237B80037F19A /* ASStackBaselinePositionedLayout.mm */,
 				ACF6ED461B17847A00DA7C62 /* ASStackLayoutSpecUtilities.h */,
 				ACF6ED471B17847A00DA7C62 /* ASStackPositionedLayout.h */,
 				ACF6ED481B17847A00DA7C62 /* ASStackPositionedLayout.mm */,
@@ -1962,7 +1953,6 @@
 				254C6B751BF94DF4003EC431 /* ASTextKitComponents.h in Headers */,
 				B35062081B010EFD0018CF92 /* ASScrollNode.h in Headers */,
 				25E327571C16819500A2170C /* ASPagerNode.h in Headers */,
-				9C8221961BA237B80037F19A /* ASStackBaselinePositionedLayout.h in Headers */,
 				9C70F20E1CDBE9E5007D6C76 /* NSArray+Diffing.h in Headers */,
 				9C49C3701B853961000B0DD5 /* ASStackLayoutElement.h in Headers */,
 				DE040EF91C2B40AC004692FF /* ASCollectionViewFlowLayoutInspector.h in Headers */,
@@ -2302,7 +2292,6 @@
 				9C8898BB1C738B9800D6B02E /* ASTextKitFontSizeAdjuster.mm in Sources */,
 				D785F6631A74327E00291744 /* ASScrollNode.mm in Sources */,
 				E5711A2E1C840C96009619D4 /* ASIndexedNodeContext.mm in Sources */,
-				9C8221971BA237B80037F19A /* ASStackBaselinePositionedLayout.mm in Sources */,
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 				ACF6ED301B17843500DA7C62 /* ASStackLayoutSpec.mm in Sources */,
 				257754BE1BEE458E00737CA5 /* ASTextKitComponents.mm in Sources */,
@@ -2496,7 +2485,6 @@
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 				509E68601B3AED8E009B9150 /* ASScrollDirection.m in Sources */,
 				B35062091B010EFD0018CF92 /* ASScrollNode.mm in Sources */,
-				9C8221981BA237B80037F19A /* ASStackBaselinePositionedLayout.mm in Sources */,
 				8BDA5FC81CDBDF95007D13B2 /* ASVideoPlayerNode.mm in Sources */,
 				34EFC7721B701D0300AD841F /* ASStackLayoutSpec.mm in Sources */,
 				34EFC7761B701D2A00AD841F /* ASStackPositionedLayout.mm in Sources */,

AsyncDisplayKit/Layout/ASStackLayoutSpec.h

@@ -59,8 +59,6 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, assign) ASStackLayoutJustifyContent justifyContent;
 /** Orientation of children along cross axis. Defaults to ASStackLayoutAlignItemsStretch */
 @property (nonatomic, assign) ASStackLayoutAlignItems alignItems;
-/** If YES the vertical spacing between two views is measured from the last baseline of the top view to the top of the bottom view */
-@property (nonatomic, assign) BOOL baselineRelativeArrangement;
 
 - (instancetype)init;
 

AsyncDisplayKit/Layout/ASStackLayoutSpec.mm

@@ -11,12 +11,15 @@
 #import <numeric>
 #import <vector>
 
+#import "ASStackLayoutSpec.h"
+#import "ASDimension.h"
 #import "ASInternalHelpers.h"
-
+#import "ASLayout.h"
 #import "ASLayoutElement.h"
 #import "ASLayoutElementStylePrivate.h"
 #import "ASLayoutSpecUtilities.h"
-#import "ASStackBaselinePositionedLayout.h"
+#import "ASStackPositionedLayout.h"
+#import "ASStackUnpositionedLayout.h"
 #import "ASThread.h"
 
 @implementation ASStackLayoutSpec
@@ -111,12 +114,6 @@ - (void)setSpacing:(CGFloat)spacing
   _spacing = spacing;
 }
 
-- (void)setBaselineRelativeArrangement:(BOOL)baselineRelativeArrangement
-{
-  ASDisplayNodeAssert(self.isMutable, @"Cannot set properties when layout spec is not mutable");
-  _baselineRelativeArrangement = baselineRelativeArrangement;
-}
-
 - (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
 {
   NSArray *children = self.children;
@@ -131,53 +128,21 @@ - (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
     return {child, style, style.size};
   });
 
-  const ASStackLayoutSpecStyle style = {.direction = _direction, .spacing = _spacing, .justifyContent = _justifyContent, .alignItems = _alignItems, .baselineRelativeArrangement = _baselineRelativeArrangement};
+  const ASStackLayoutSpecStyle style = {.direction = _direction, .spacing = _spacing, .justifyContent = _justifyContent, .alignItems = _alignItems};
 
-  // First pass is to get the children into a positioned state
   const auto unpositionedLayout = ASStackUnpositionedLayout::compute(stackChildren, style, constrainedSize);
   const auto positionedLayout = ASStackPositionedLayout::compute(unpositionedLayout, style, constrainedSize);
 
-  // Figure out if a baseline pass is really needed
-  const BOOL directionIsVertical = (style.direction == ASStackLayoutDirectionVertical);
-  const BOOL needsBaselineAlignment = ASStackBaselinePositionedLayout::needsBaselineAlignment(style);
-  const BOOL needsBaselinePositioning = (directionIsVertical == NO || needsBaselineAlignment == YES);
-  
-  NSMutableArray *sublayouts = [NSMutableArray array];
-  CGSize finalSize = CGSizeZero;
-  if (needsBaselinePositioning) {
-    // All horizontal stacks, regardless of whether or not they are baseline aligned, should go through a baseline
-    // computation. They could be used in another horizontal stack that is baseline aligned and will need to have
-    // computed the proper ascender/descender.
-    
-    // Vertical stacks do not need to go through this computation since we can easily compute ascender/descender by
-    // looking at their first/last child's ascender/descender.
-    const auto baselinePositionedLayout = ASStackBaselinePositionedLayout::compute(positionedLayout, style, constrainedSize);
-
-    if (directionIsVertical == NO) {
-      self.style.ascender = baselinePositionedLayout.ascender;
-      self.style.descender = baselinePositionedLayout.descender;
-    }
-    
-    if (needsBaselineAlignment == YES) {
-      finalSize = directionSize(style.direction, unpositionedLayout.stackDimensionSum, baselinePositionedLayout.crossSize);
-
-      for (const auto &l : baselinePositionedLayout.items) {
-        [sublayouts addObject:l.layout];
-      }
-    }
-  }
-  
-  if (directionIsVertical == YES) {
+  if (style.direction == ASStackLayoutDirectionVertical) {
     self.style.ascender = stackChildren.front().style.ascender;
     self.style.descender = stackChildren.back().style.descender;
   }
 
-  if (needsBaselineAlignment == NO) {
-    finalSize = directionSize(style.direction, unpositionedLayout.stackDimensionSum, positionedLayout.crossSize);
-    
-    for (const auto &l : positionedLayout.items) {
-      [sublayouts addObject:l.layout];
-    }
+  const CGSize finalSize = directionSize(style.direction, unpositionedLayout.stackDimensionSum, unpositionedLayout.crossSize);
+  
+  NSMutableArray *sublayouts = [NSMutableArray array];
+  for (const auto &l : positionedLayout.items) {
+    [sublayouts addObject:l.layout];
   }
 
   return [ASLayout layoutWithLayoutElement:self size:ASSizeRangeClamp(constrainedSize, finalSize) sublayouts:sublayouts];