Merge pull request facebookarchive#2627 from maicki/MSFixStackLayoutS…

…paceRounding

[ASStackLayoutSpec] Don’t floor space between items for ASStackLayoutJustifyContentSpaceBetween and ASStackLayoutJustifyContentSpaceAround

AsyncDisplayKit/Private/ASStackPositionedLayout.mm

@@ -118,12 +118,13 @@ static ASStackPositionedLayout stackedLayout(const ASStackLayoutSpecStyle &style
  return stackedLayout(style, violation, unpositionedLayout, constrainedSize);
  }
  case ASStackLayoutJustifyContentSpaceBetween: {
+ // Spacing between the items, no spaces at the edges, evenly distributed
  const auto numOfSpacings = numOfItems - 1;
- return stackedLayout(style, 0, std::floor(violation / numOfSpacings), std::fmod(violation, numOfSpacings), unpositionedLayout, constrainedSize);
+ return stackedLayout(style, 0, violation / numOfSpacings, 0, unpositionedLayout, constrainedSize);
  }
  case ASStackLayoutJustifyContentSpaceAround: {
  // Spacing between items are twice the spacing on the edges
- CGFloat spacingUnit = std::floor(violation / (numOfItems * 2));
+ CGFloat spacingUnit = violation / (numOfItems * 2);
  return stackedLayout(style, spacingUnit, spacingUnit * 2, 0, unpositionedLayout, constrainedSize);
  }
  }

AsyncDisplayKitTests/ASStackLayoutSpecSnapshotTests.mm

@@ -340,14 +340,14 @@ - (void)testJustifiedSpaceAroundWithOneChild
 
 - (void)testJustifiedSpaceBetweenWithRemainingSpace
 {
- // width 301px; height 0-300px; 1px remaining
+ // width 301px; height 0-300px;
  static ASSizeRange kSize = {{301, 0}, {301, 300}};
  [self testStackLayoutSpecWithJustify:ASStackLayoutJustifyContentSpaceBetween flexFactor:0 sizeRange:kSize identifier:nil];
 }
 
 - (void)testJustifiedSpaceAroundWithRemainingSpace
 {
- // width 305px; height 0-300px; 5px remaining
+ // width 305px; height 0-300px;
  static ASSizeRange kSize = {{305, 0}, {305, 300}};
  [self testStackLayoutSpecWithJustify:ASStackLayoutJustifyContentSpaceAround flexFactor:0 sizeRange:kSize identifier:nil];
 }