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Fix ASTextNode size calculation when paragraphstyle has linespacing #939

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Fix ASTextNode size calculation when paragraphstyle has linespacing #939

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7ec7e68
Fix paragraph linespacing of last line not taken into account in ASTe…
samhsiung Dec 14, 2015
cc9dd89
tweak doc for linespacing workaround
samhsiung Dec 14, 2015
b8c83fc
add rdar bug link and only pull paragraph style from last visible glyph
samhsiung Dec 14, 2015
d1d8c4a
move doc
samhsiung Dec 14, 2015
010d6bb
customize linespacing for last line of ASTextNode used in ASTextNodeT…
samhsiung Dec 15, 2015
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Binary file modified AsyncDisplayKit-Prefix.gcda
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19 changes: 19 additions & 0 deletions AsyncDisplayKit/TextKit/ASTextKitRenderer.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,25 @@ - (void)_calculateSize
__block CGRect boundingRect;
[_context performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
boundingRect = [layoutManager usedRectForTextContainer:textContainer];

// Work around line spacing of the last line not getting taken into account
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So is this a TextKit bug? Were you able to find any other reports of it online? Ideally we should file a Radar for this and reference the number here...almost certainly this code will break in a future version of iOS (if it is a workaround), and thus a future version of ourselves will be puzzling over the intent and context here.

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Couldn't find anything on google. Logged a bug rdar://23885167.

// (rdar://23885167)
NSRange visibleGlyphRange = [layoutManager glyphRangeForBoundingRect:constrainedRect
inTextContainer:textContainer];
NSInteger lastVisibleGlyphIndex = (NSMaxRange(visibleGlyphRange) - 1);
NSInteger lastVisibleGlyphAttributeIndex = [layoutManager characterIndexForGlyphAtIndex:lastVisibleGlyphIndex];

NSParagraphStyle *paragraphStyle = [textStorage attributesAtIndex:lastVisibleGlyphAttributeIndex
effectiveRange:NULL][NSParagraphStyleAttributeName];

if (paragraphStyle.lineSpacing > 0) {
CGSize boundingSize = boundingRect.size;
CGSize sizeWithLineSpacing = CGSizeMake(boundingSize.width,
boundingSize.height + paragraphStyle.lineSpacing);
boundingRect = (CGRect){ .origin = boundingRect.origin,
.size = sizeWithLineSpacing };
}

}];

// TextKit often returns incorrect glyph bounding rects in the horizontal direction, so we clip to our bounding rect
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12 changes: 11 additions & 1 deletion AsyncDisplayKitTests/ASTextNodeTests.m
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Expand Up @@ -69,7 +69,17 @@ - (void)setUp
[[NSMutableAttributedString alloc] initWithString:@"Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum." attributes:d];
NSMutableParagraphStyle *para = [NSMutableParagraphStyle new];
para.alignment = NSTextAlignmentCenter;
[mas addAttribute:NSParagraphStyleAttributeName value:para range:NSMakeRange(0,mas.length)];
para.lineSpacing = 1.0;
[mas addAttribute:NSParagraphStyleAttributeName value:para
range:NSMakeRange(0, mas.length - 1)];

// Vary the linespacing on the last line
NSMutableParagraphStyle *lastLinePara = [NSMutableParagraphStyle new];
lastLinePara.alignment = para.alignment;
lastLinePara.lineSpacing = 5.0;
[mas addAttribute:NSParagraphStyleAttributeName value:lastLinePara
range:NSMakeRange(mas.length - 1, 1)];

_attributedString = mas;
_textNode.attributedString = _attributedString;
}
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