[ASStackLayoutSpec] Flex wrap fix and lineSpacing property

CHANGELOG.md

@@ -1,6 +1,8 @@
 ## master
 
 * Add your own contributions to the next release on the line below this with your name.
+- [ASStackLayoutSpec] Add lineSpacing property working with flex wrap. [Flo Vouin](https://github.com/flovouin)
+- [ASStackLayoutSpec] Fix flex wrap overflow in some cases using item spacing. [Flo Vouin](https://github.com/flovouin)
 - [ASNodeController] Add -nodeDidLayout callback. Allow switching retain behavior at runtime. [Scott Goodson](https://github.com/appleguy)
 - [ASCollectionView] Add delegate bridging and index space translation for missing UICollectionViewLayout properties. [Scott Goodson](https://github.com/appleguy)
 - [ASTextNode2] Add initial implementation for link handling. [Scott Goodson](https://github.com/appleguy) [#396](https://github.com/TextureGroup/Texture/pull/396)

Source/Layout/ASStackLayoutSpec.h

@@ -70,6 +70,8 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, assign) ASStackLayoutFlexWrap flexWrap;
 /** Orientation of lines along cross axis if there are multiple lines. Defaults to ASStackLayoutAlignContentStart */
 @property (nonatomic, assign) ASStackLayoutAlignContent alignContent;
+/** If the stack spreads on multiple lines using flexWrap, the amount of space between lines. */
+@property (nonatomic, assign) CGFloat lineSpacing;
 /** Whether this stack can dispatch to other threads, regardless of which thread it's running on */
 @property (nonatomic, assign, getter=isConcurrent) BOOL concurrent;
 
@@ -105,6 +107,25 @@ NS_ASSUME_NONNULL_BEGIN
                                 alignContent:(ASStackLayoutAlignContent)alignContent
                                     children:(NSArray<id<ASLayoutElement>> *)children AS_WARN_UNUSED_RESULT;
 
+/**
+ @param direction The direction of the stack view (horizontal or vertical)
+ @param spacing The spacing between the children
+ @param justifyContent If no children are flexible, this describes how to fill any extra space
+ @param alignItems Orientation of the children along the cross axis
+ @param flexWrap Whether children are stacked into a single or multiple lines
+ @param alignContent Orientation of lines along cross axis if there are multiple lines
+ @param lineSpacing The spacing between lines
+ @param children ASLayoutElement children to be positioned.
+ */
++ (instancetype)stackLayoutSpecWithDirection:(ASStackLayoutDirection)direction
+                                     spacing:(CGFloat)spacing
+                              justifyContent:(ASStackLayoutJustifyContent)justifyContent
+                                  alignItems:(ASStackLayoutAlignItems)alignItems
+                                    flexWrap:(ASStackLayoutFlexWrap)flexWrap
+                                alignContent:(ASStackLayoutAlignContent)alignContent
+                                 lineSpacing:(CGFloat)lineSpacing
+                                    children:(NSArray<id<ASLayoutElement>> *)children AS_WARN_UNUSED_RESULT;
+
 /**
  * @return A stack layout spec with direction of ASStackLayoutDirectionVertical
  **/

Source/Layout/ASStackLayoutSpec.mm

@@ -33,17 +33,22 @@ @implementation ASStackLayoutSpec
 
 - (instancetype)init
 {
-  return [self initWithDirection:ASStackLayoutDirectionHorizontal spacing:0.0 justifyContent:ASStackLayoutJustifyContentStart alignItems:ASStackLayoutAlignItemsStretch flexWrap:ASStackLayoutFlexWrapNoWrap alignContent:ASStackLayoutAlignContentStart children:nil];
+  return [self initWithDirection:ASStackLayoutDirectionHorizontal spacing:0.0 justifyContent:ASStackLayoutJustifyContentStart alignItems:ASStackLayoutAlignItemsStretch flexWrap:ASStackLayoutFlexWrapNoWrap alignContent:ASStackLayoutAlignContentStart lineSpacing:0.0 children:nil];
 }
 
 + (instancetype)stackLayoutSpecWithDirection:(ASStackLayoutDirection)direction spacing:(CGFloat)spacing justifyContent:(ASStackLayoutJustifyContent)justifyContent alignItems:(ASStackLayoutAlignItems)alignItems children:(NSArray *)children
 {
-  return [[self alloc] initWithDirection:direction spacing:spacing justifyContent:justifyContent alignItems:alignItems flexWrap:ASStackLayoutFlexWrapNoWrap alignContent:ASStackLayoutAlignContentStart children:children];
+  return [[self alloc] initWithDirection:direction spacing:spacing justifyContent:justifyContent alignItems:alignItems flexWrap:ASStackLayoutFlexWrapNoWrap alignContent:ASStackLayoutAlignContentStart lineSpacing: 0.0 children:children];
 }
 
 + (instancetype)stackLayoutSpecWithDirection:(ASStackLayoutDirection)direction spacing:(CGFloat)spacing justifyContent:(ASStackLayoutJustifyContent)justifyContent alignItems:(ASStackLayoutAlignItems)alignItems flexWrap:(ASStackLayoutFlexWrap)flexWrap alignContent:(ASStackLayoutAlignContent)alignContent children:(NSArray<id<ASLayoutElement>> *)children
 {
-  return [[self alloc] initWithDirection:direction spacing:spacing justifyContent:justifyContent alignItems:alignItems flexWrap:flexWrap alignContent:alignContent children:children];
+  return [[self alloc] initWithDirection:direction spacing:spacing justifyContent:justifyContent alignItems:alignItems flexWrap:flexWrap alignContent:alignContent lineSpacing:0.0 children:children];
+}
+
++ (instancetype)stackLayoutSpecWithDirection:(ASStackLayoutDirection)direction spacing:(CGFloat)spacing justifyContent:(ASStackLayoutJustifyContent)justifyContent alignItems:(ASStackLayoutAlignItems)alignItems flexWrap:(ASStackLayoutFlexWrap)flexWrap alignContent:(ASStackLayoutAlignContent)alignContent lineSpacing:(CGFloat)lineSpacing children:(NSArray<id<ASLayoutElement>> *)children
+{
+  return [[self alloc] initWithDirection:direction spacing:spacing justifyContent:justifyContent alignItems:alignItems flexWrap:flexWrap alignContent:alignContent lineSpacing:lineSpacing children:children];
 }
 
 + (instancetype)verticalStackLayoutSpec
@@ -60,7 +65,7 @@ + (instancetype)horizontalStackLayoutSpec
   return stackLayoutSpec;
 }
 
-- (instancetype)initWithDirection:(ASStackLayoutDirection)direction spacing:(CGFloat)spacing justifyContent:(ASStackLayoutJustifyContent)justifyContent alignItems:(ASStackLayoutAlignItems)alignItems flexWrap:(ASStackLayoutFlexWrap)flexWrap alignContent:(ASStackLayoutAlignContent)alignContent children:(NSArray *)children
+- (instancetype)initWithDirection:(ASStackLayoutDirection)direction spacing:(CGFloat)spacing justifyContent:(ASStackLayoutJustifyContent)justifyContent alignItems:(ASStackLayoutAlignItems)alignItems flexWrap:(ASStackLayoutFlexWrap)flexWrap alignContent:(ASStackLayoutAlignContent)alignContent lineSpacing:(CGFloat)lineSpacing children:(NSArray *)children
 {
   if (!(self = [super init])) {
     return nil;
@@ -73,6 +78,7 @@ - (instancetype)initWithDirection:(ASStackLayoutDirection)direction spacing:(CGF
   _justifyContent = justifyContent;
   _flexWrap = flexWrap;
   _alignContent = alignContent;
+  _lineSpacing = lineSpacing;
 
   [self setChildren:children];
   return self;
@@ -144,7 +150,7 @@ - (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
     return {child, style, style.size};
   });
 
-  const ASStackLayoutSpecStyle style = {.direction = _direction, .spacing = _spacing, .justifyContent = _justifyContent, .alignItems = _alignItems, .flexWrap = _flexWrap, .alignContent = _alignContent};
+  const ASStackLayoutSpecStyle style = {.direction = _direction, .spacing = _spacing, .justifyContent = _justifyContent, .alignItems = _alignItems, .flexWrap = _flexWrap, .alignContent = _alignContent, .lineSpacing = _lineSpacing};
 
   const auto unpositionedLayout = ASStackUnpositionedLayout::compute(stackChildren, style, constrainedSize, _concurrent);
   const auto positionedLayout = ASStackPositionedLayout::compute(unpositionedLayout, style, constrainedSize);

Source/Private/Layout/ASStackLayoutSpecUtilities.h

@@ -24,6 +24,7 @@ typedef struct {
   ASStackLayoutAlignItems alignItems;
   ASStackLayoutFlexWrap flexWrap;
   ASStackLayoutAlignContent alignContent;
+  CGFloat lineSpacing;
 } ASStackLayoutSpecStyle;
 
 inline CGFloat stackDimension(const ASStackLayoutDirection direction, const CGSize size)

Source/Private/Layout/ASStackPositionedLayout.mm

@@ -160,6 +160,7 @@ static void positionItemsInLine(const ASStackUnpositionedLine &line,
   const auto numOfLines = lines.size();
   const auto direction = style.direction;
   const auto alignContent = style.alignContent;
+  const auto lineSpacing = style.lineSpacing;
   const auto justifyContent = style.justifyContent;
   const auto crossViolation = ASStackUnpositionedLayout::computeCrossViolation(layout.crossDimensionSum, style, sizeRange);
   CGFloat crossOffset;
@@ -171,7 +172,7 @@ static void positionItemsInLine(const ASStackUnpositionedLine &line,
   BOOL first = YES;
   for (const auto &line : lines) {
     if (!first) {
-      p = p + directionPoint(direction, 0, crossSpacing);
+      p = p + directionPoint(direction, 0, crossSpacing + lineSpacing);
     }
     first = NO;
 

Source/Private/Layout/ASStackUnpositionedLayout.mm

@@ -113,9 +113,12 @@ static void dispatchApplyIfNeeded(size_t iterationCount, BOOL forced, void(^work
 
  @param lines unpositioned lines
  */
-static CGFloat computeLinesCrossDimensionSum(const std::vector<ASStackUnpositionedLine> &lines)
+static CGFloat computeLinesCrossDimensionSum(const std::vector<ASStackUnpositionedLine> &lines,
+                                             const ASStackLayoutSpecStyle &style)
 {
-  return std::accumulate(lines.begin(), lines.end(), 0.0,
+  return std::accumulate(lines.begin(), lines.end(),
+                         // Start from default spacing between each line:
+                         lines.empty() ? 0 : style.lineSpacing * (lines.size() - 1),
                          [&](CGFloat x, const ASStackUnpositionedLine &l) {
                            return x + l.crossSize;
                          });
@@ -236,7 +239,7 @@ static void stretchLinesAlongCrossDimension(std::vector<ASStackUnpositionedLine>
 {
   ASDisplayNodeCAssertFalse(lines.empty());
   const std::size_t numOfLines = lines.size();
-  const CGFloat violation = ASStackUnpositionedLayout::computeCrossViolation(computeLinesCrossDimensionSum(lines), style, sizeRange);
+  const CGFloat violation = ASStackUnpositionedLayout::computeCrossViolation(computeLinesCrossDimensionSum(lines, style), style, sizeRange);
   // Don't stretch if the stack is single line, because the line's cross size was clamped against the stack's constrained size.
   const BOOL shouldStretchLines = (numOfLines > 1
                                    && style.alignContent == ASStackLayoutAlignContentStretch
@@ -648,7 +651,8 @@ static void flexLinesAlongStackDimension(std::vector<ASStackUnpositionedLine> &l
   for(auto it = items.begin(); it != items.end(); ++it) {
     const auto &item = *it;
     const CGFloat itemStackDimension = stackDimension(style.direction, item.layout.size);
-    const BOOL negativeViolationIfAddItem = (ASStackUnpositionedLayout::computeStackViolation(lineStackDimensionSum + itemStackDimension, style, sizeRange) < 0);
+    const CGFloat itemAndSpacingStackDimension = (lineItems.empty() ? 0.0 : style.spacing) + item.child.style.spacingBefore + itemStackDimension + item.child.style.spacingAfter;
+    const BOOL negativeViolationIfAddItem = (ASStackUnpositionedLayout::computeStackViolation(lineStackDimensionSum + itemAndSpacingStackDimension, style, sizeRange) < 0);
     const BOOL breakCurrentLine = negativeViolationIfAddItem && !lineItems.empty();
 
     if (breakCurrentLine) {
@@ -658,7 +662,7 @@ static void flexLinesAlongStackDimension(std::vector<ASStackUnpositionedLine> &l
     }
 
     lineItems.push_back(std::move(item));
-    lineStackDimensionSum += itemStackDimension;
+    lineStackDimensionSum += itemAndSpacingStackDimension;
   }
 
   // Handle last line
@@ -752,7 +756,7 @@ static void layoutItemsAlongUnconstrainedStackDimension(std::vector<ASStackLayou
   }
   // Compute cross dimension sum of the stack.
   // This should be done before `lines` are moved to a new ASStackUnpositionedLayout struct (i.e `std::move(lines)`)
-  CGFloat layoutCrossDimensionSum = computeLinesCrossDimensionSum(lines);
+  CGFloat layoutCrossDimensionSum = computeLinesCrossDimensionSum(lines, style);
 
   return {.lines = std::move(lines), .stackDimensionSum = layoutStackDimensionSum, .crossDimensionSum = layoutCrossDimensionSum};
 }