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Fixes to baseline stack alignment

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1) Set the ascender/descender of an ASTextNode when the attributeString is set. Previously ascender/descender were only being computed in `setValuesFromLayoutable` and only when the attribute string was not nil. May make sense to remove the computation from `setValuesFromLayoutable` entirely.
2) Remove ability to allow different children of a stack spec to aling to different baselines. This wasn't working before and I'm not convinced it is possible to do properly/useful enough to invest the time.
3) Have all stack spec run `ASStackBaselinePositionedLayout::compute` to compute the stack's ascender and descender. Even if the stack isn't aligning its children to a baseline, the stack itself may be a child of another stack that IS aligning to a baseline.
This commit is contained in:
ricky cancro
2015-10-06 21:41:39 -07:00
parent e41f7c59c4
commit 89a216b90d
5 changed files with 56 additions and 42 deletions
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7
AsyncDisplayKit/ASTextNode.mm
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@@ -17,6 +17,7 @@
#import <AsyncDisplayKit/ASTextNodeTextKitHelpers.h> #import <AsyncDisplayKit/ASTextNodeTextKitHelpers.h>
#import <AsyncDisplayKit/ASDisplayNodeExtras.h> #import <AsyncDisplayKit/ASDisplayNodeExtras.h>
#import "ASInternalHelpers.h"
#import "ASTextNodeRenderer.h" #import "ASTextNodeRenderer.h"
#import "ASTextNodeShadower.h" #import "ASTextNodeShadower.h"
#import "ASEqualityHelpers.h" #import "ASEqualityHelpers.h"
@@ -344,6 +345,12 @@ static NSString *ASTextNodeTruncationTokenAttributeName = @"ASTextNodeTruncation
self.isAccessibilityElement = YES; self.isAccessibilityElement = YES;
} }
}); });
if (attributedString.length > 0) {
CGFloat screenScale = ASScreenScale();
self.ascender = round([[attributedString attribute:NSFontAttributeName atIndex:0 effectiveRange:NULL] ascender] * screenScale)/screenScale;
self.descender = round([[attributedString attribute:NSFontAttributeName atIndex:attributedString.length - 1 effectiveRange:NULL] descender] * screenScale)/screenScale;
}
} }
#pragma mark - Text Layout #pragma mark - Text Layout

8
AsyncDisplayKit/Layout/ASStackLayoutDefines.h
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@@ -45,9 +45,9 @@ typedef NS_ENUM(NSUInteger, ASStackLayoutAlignItems) {
ASStackLayoutAlignItemsCenter, ASStackLayoutAlignItemsCenter,
/** Expand children to fill cross axis */ /** Expand children to fill cross axis */
ASStackLayoutAlignItemsStretch, ASStackLayoutAlignItemsStretch,
/** Children align to their first baseline. Only available for horizontal stack nodes */ /** Children align to their first baseline. Only available for horizontal stack spec */
ASStackLayoutAlignItemsBaselineFirst, ASStackLayoutAlignItemsBaselineFirst,
/** Children align to their last baseline. Only available for horizontal stack nodes */ /** Children align to their last baseline. Only available for horizontal stack spec */
ASStackLayoutAlignItemsBaselineLast, ASStackLayoutAlignItemsBaselineLast,
}; };
@@ -66,8 +66,4 @@ typedef NS_ENUM(NSUInteger, ASStackLayoutAlignSelf) {
ASStackLayoutAlignSelfCenter, ASStackLayoutAlignSelfCenter,
/** Expand to fill cross axis */ /** Expand to fill cross axis */
ASStackLayoutAlignSelfStretch, ASStackLayoutAlignSelfStretch,
/** Children align to their first baseline. Only available for horizontal stack nodes */
ASStackLayoutAlignSelfBaselineFirst,
/** Children align to their last baseline. Only available for horizontal stack nodes */
ASStackLayoutAlignSelfBaselineLast,
}; };

16
AsyncDisplayKit/Layout/ASStackLayoutSpec.mm
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@@ -101,7 +101,6 @@
std::vector<id<ASLayoutable>> stackChildren = std::vector<id<ASLayoutable>>(); std::vector<id<ASLayoutable>> stackChildren = std::vector<id<ASLayoutable>>();
for (id<ASLayoutable> child in self.children) { for (id<ASLayoutable> child in self.children) {
stackChildren.push_back(child); stackChildren.push_back(child);
needsBaselinePass |= child.alignSelf == ASStackLayoutAlignSelfBaselineFirst || child.alignSelf == ASStackLayoutAlignSelfBaselineLast;
} }
const auto unpositionedLayout = ASStackUnpositionedLayout::compute(stackChildren, style, constrainedSize); const auto unpositionedLayout = ASStackUnpositionedLayout::compute(stackChildren, style, constrainedSize);
@@ -109,12 +108,21 @@
CGSize finalSize = CGSizeZero; CGSize finalSize = CGSizeZero;
NSArray *sublayouts = nil; NSArray *sublayouts = nil;
if (needsBaselinePass) {
const auto baselinePositionedLayout = ASStackBaselinePositionedLayout::compute(positionedLayout, style, constrainedSize); // regardless of whether or not this stack aligns to baseline, we should let ASStackBaselinePositionedLayout::compute find the max ascender
// and min descender in case this spec is a child in another spec that wants to align to a baseline.
const auto baselinePositionedLayout = ASStackBaselinePositionedLayout::compute(positionedLayout, style, constrainedSize);
if (self.direction == ASStackLayoutDirectionVertical) {
ASDN::MutexLocker l(_propertyLock);
self.ascender = [[self.children firstObject] ascender];
self.descender = [[self.children lastObject] descender];
} else {
ASDN::MutexLocker l(_propertyLock); ASDN::MutexLocker l(_propertyLock);
self.ascender = baselinePositionedLayout.ascender; self.ascender = baselinePositionedLayout.ascender;
self.descender = baselinePositionedLayout.descender; self.descender = baselinePositionedLayout.descender;
}
if (needsBaselinePass) {
finalSize = directionSize(style.direction, unpositionedLayout.stackDimensionSum, baselinePositionedLayout.crossSize); finalSize = directionSize(style.direction, unpositionedLayout.stackDimensionSum, baselinePositionedLayout.crossSize);
sublayouts = [NSArray arrayWithObjects:&baselinePositionedLayout.sublayouts[0] count:baselinePositionedLayout.sublayouts.size()]; sublayouts = [NSArray arrayWithObjects:&baselinePositionedLayout.sublayouts[0] count:baselinePositionedLayout.sublayouts.size()];
} else { } else {

63
AsyncDisplayKit/Private/ASStackBaselinePositionedLayout.mm
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@@ -93,7 +93,7 @@ ASStackBaselinePositionedLayout ASStackBaselinePositionedLayout::compute(const A
const auto ascenderIt = std::max_element(positionedLayout.sublayouts.begin(), positionedLayout.sublayouts.end(), [&](const ASLayout *a, const ASLayout *b){ const auto ascenderIt = std::max_element(positionedLayout.sublayouts.begin(), positionedLayout.sublayouts.end(), [&](const ASLayout *a, const ASLayout *b){
return a.layoutableObject.ascender < b.layoutableObject.ascender; return a.layoutableObject.ascender < b.layoutableObject.ascender;
}); });
const CGFloat maxAscender = baselineIt == positionedLayout.sublayouts.end() ? 0 : (*ascenderIt).layoutableObject.ascender; const CGFloat maxAscender = ascenderIt == positionedLayout.sublayouts.end() ? 0 : (*ascenderIt).layoutableObject.ascender;
/* /*
Step 3: Take each child and update its layout position based on the baseline offset. Step 3: Take each child and update its layout position based on the baseline offset.
@@ -103,33 +103,40 @@ ASStackBaselinePositionedLayout ASStackBaselinePositionedLayout::compute(const A
spacing between the two nodes is from the baseline, not the bounding box. spacing between the two nodes is from the baseline, not the bounding box.
*/ */
CGPoint p = CGPointZero; std::vector<ASLayout *> stackedChildren;
BOOL first = YES; // Only change positions of layouts this stackSpec is aligning to a baseline. Otherwise we are only here to
auto stackedChildren = AS::map(positionedLayout.sublayouts, [&](ASLayout *l) -> ASLayout *{ // compute the min/max descender/ascender for this stack spec.
__weak id<ASLayoutable> child = l.layoutableObject; if (style.baselineRelativeArrangement || style.alignItems == ASStackLayoutAlignItemsBaselineFirst || style.alignItems == ASStackLayoutAlignItemsBaselineLast) {
p = p + directionPoint(style.direction, child.spacingBefore, 0); CGPoint p = CGPointZero;
if (first) { BOOL first = YES;
// if this is the first item use the previously computed start point stackedChildren = AS::map(positionedLayout.sublayouts, [&](ASLayout *l) -> ASLayout *{
p = l.position; __weak id<ASLayoutable> child = l.layoutableObject;
} else { p = p + directionPoint(style.direction, child.spacingBefore, 0);
// otherwise add the stack spacing if (first) {
p = p + directionPoint(style.direction, style.spacing, 0); // if this is the first item use the previously computed start point
} p = l.position;
first = NO; } else {
// otherwise add the stack spacing
// Find the difference between this node's baseline and the max baseline of all the children. Add this difference to the child's y position. p = p + directionPoint(style.direction, style.spacing, 0);
l.position = p + CGPointMake(0, baselineOffset(style, l, maxAscender, maxBaseline)); }
first = NO;
// If we are a vertical stack, add the item's descender (it is negative) to the offset for the next node. This will ensure we are spacing
// node from baselines and not bounding boxes. // Find the difference between this node's baseline and the max baseline of all the children. Add this difference to the child's y position.
CGFloat spacingAfterBaseline = 0; l.position = p + CGPointMake(0, baselineOffset(style, l, maxAscender, maxBaseline));
if (style.direction == ASStackLayoutDirectionVertical) {
spacingAfterBaseline = child.descender; // If we are a vertical stack, add the item's descender (it is negative) to the offset for the next node. This will ensure we are spacing
} // node from baselines and not bounding boxes.
p = p + directionPoint(style.direction, stackDimension(style.direction, l.size) + child.spacingAfter + spacingAfterBaseline, 0); CGFloat spacingAfterBaseline = 0;
if (style.direction == ASStackLayoutDirectionVertical) {
return l; spacingAfterBaseline = child.descender;
}); }
p = p + directionPoint(style.direction, stackDimension(style.direction, l.size) + child.spacingAfter + spacingAfterBaseline, 0);
return l;
});
} else {
stackedChildren = positionedLayout.sublayouts;
}
/* /*
Step 4: Since we have been mucking with positions, there is a chance that our cross size has changed. Imagine a node with a font size of 40 Step 4: Since we have been mucking with positions, there is a chance that our cross size has changed. Imagine a node with a font size of 40

4
AsyncDisplayKit/Private/ASStackLayoutSpecUtilities.h
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@@ -63,10 +63,6 @@ inline ASStackLayoutAlignItems alignment(ASStackLayoutAlignSelf childAlignment,
return ASStackLayoutAlignItemsStart; return ASStackLayoutAlignItemsStart;
case ASStackLayoutAlignSelfStretch: case ASStackLayoutAlignSelfStretch:
return ASStackLayoutAlignItemsStretch; return ASStackLayoutAlignItemsStretch;
case ASStackLayoutAlignSelfBaselineFirst:
return ASStackLayoutAlignItemsBaselineFirst;
case ASStackLayoutAlignSelfBaselineLast:
return ASStackLayoutAlignItemsBaselineLast;
case ASStackLayoutAlignSelfAuto: case ASStackLayoutAlignSelfAuto:
default: default:
return stackAlignment; return stackAlignment;