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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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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){
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.
@@ -103,33 +103,40 @@ ASStackBaselinePositionedLayout ASStackBaselinePositionedLayout::compute(const A
spacing between the two nodes is from the baseline, not the bounding box.
*/
CGPoint p = CGPointZero;
BOOL first = YES;
auto stackedChildren = AS::map(positionedLayout.sublayouts, [&](ASLayout *l) -> ASLayout *{
__weak id<ASLayoutable> child = l.layoutableObject;
p = p + directionPoint(style.direction, child.spacingBefore, 0);
if (first) {
// if this is the first item use the previously computed start point
p = l.position;
} else {
// otherwise add the stack spacing
p = p + directionPoint(style.direction, style.spacing, 0);
}
first = NO;
// 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.
l.position = p + CGPointMake(0, baselineOffset(style, l, maxAscender, maxBaseline));
// 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.
CGFloat spacingAfterBaseline = 0;
if (style.direction == ASStackLayoutDirectionVertical) {
spacingAfterBaseline = child.descender;
}
p = p + directionPoint(style.direction, stackDimension(style.direction, l.size) + child.spacingAfter + spacingAfterBaseline, 0);
return l;
});
std::vector<ASLayout *> stackedChildren;
// Only change positions of layouts this stackSpec is aligning to a baseline. Otherwise we are only here to
// compute the min/max descender/ascender for this stack spec.
if (style.baselineRelativeArrangement || style.alignItems == ASStackLayoutAlignItemsBaselineFirst || style.alignItems == ASStackLayoutAlignItemsBaselineLast) {
CGPoint p = CGPointZero;
BOOL first = YES;
stackedChildren = AS::map(positionedLayout.sublayouts, [&](ASLayout *l) -> ASLayout *{
__weak id<ASLayoutable> child = l.layoutableObject;
p = p + directionPoint(style.direction, child.spacingBefore, 0);
if (first) {
// if this is the first item use the previously computed start point
p = l.position;
} else {
// otherwise add the stack spacing
p = p + directionPoint(style.direction, style.spacing, 0);
}
first = NO;
// 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.
l.position = p + CGPointMake(0, baselineOffset(style, l, maxAscender, maxBaseline));
// 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.
CGFloat spacingAfterBaseline = 0;
if (style.direction == ASStackLayoutDirectionVertical) {
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