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YYTextLayout中计算_lineWidth的代码直接使用了CTLineGetTypographicBounds，这将在文本设置居中的时候出现一些布局的错误 #983

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CodeSlaveZhang opened this issue May 24, 2023 · 0 comments

CodeSlaveZhang commented May 24, 2023 •

edited

文本的Paragraph Style设置居中，在计算布局的时候，左侧缩进后右侧并没有缩进。这将导致计算的结果实际上是居右的。

嘛算了我描述好像不太清楚。总之就是设置居中看起来像是居右。
原始代码：

(void)setCTLine:(_Nonnull CTLineRef)CTLine {
if (_CTLine != CTLine) {
if (CTLine) CFRetain(CTLine);
if (_CTLine) CFRelease(_CTLine);
_CTLine = CTLine;
if (_CTLine) {
_lineWidth = CTLineGetTypographicBounds(_CTLine, &_ascent, &_descent, &_leading);
CFRange range = CTLineGetStringRange(_CTLine);
_range = NSMakeRange(range.location, range.length);
if (CTLineGetGlyphCount(_CTLine) > 0) {
CFArrayRef runs = CTLineGetGlyphRuns(_CTLine);
CTRunRef run = CFArrayGetValueAtIndex(runs, 0);
CGPoint pos;
CTRunGetPositions(run, CFRangeMake(0, 1), &pos);
_firstGlyphPos = pos.x;
} else {
_firstGlyphPos = 0;
}
_trailingWhitespaceWidth = CTLineGetTrailingWhitespaceWidth(_CTLine);
} else {
_lineWidth = _ascent = _descent = _leading = _firstGlyphPos = _trailingWhitespaceWidth = 0;
_range = NSMakeRange(0, 0);
}
[self reloadBounds];
}
}

修改后的代码

(void)setCTLine:(_Nonnull CTLineRef)CTLine {
if (_CTLine != CTLine) {
if (CTLine) CFRetain(CTLine);
if (_CTLine) CFRelease(_CTLine);
_CTLine = CTLine;
if (_CTLine) {
_lineWidth = CTLineGetTypographicBounds(_CTLine, &_ascent, &_descent, &_leading);
CFRange range = CTLineGetStringRange(_CTLine);
_range = NSMakeRange(range.location, range.length);
if (CTLineGetGlyphCount(_CTLine) > 0) {
CFArrayRef runs = CTLineGetGlyphRuns(_CTLine);
CTRunRef run = CFArrayGetValueAtIndex(runs, 0);
CGPoint pos;
CTRunGetPositions(run, CFRangeMake(0, 1), &pos);
_firstGlyphPos = pos.x;
**///查看是否有文字居中
NSDictionary attrs = (id)CTRunGetAttributes(run);
NSParagraphStyle paraStyle = attrs[NSParagraphStyleAttributeName];
if (paraStyle.alignment == NSTextAlignmentCenter) {
//居中的时候line的右边空白要保持和左边一致
_lineWidth += _position.x;
}
} else {
_firstGlyphPos = 0;
}
_trailingWhitespaceWidth = CTLineGetTrailingWhitespaceWidth(_CTLine);
} else {
_lineWidth = _ascent = _descent = _leading = _firstGlyphPos = _trailingWhitespaceWidth = 0;
_range = NSMakeRange(0, 0);
}
[self reloadBounds];
}
}

新增了一个在有居中的情况下的补偿宽度。另外 _trailingWhitespaceWidth这个东西干啥用的，有点烟雾弹的效果- -。感觉像是你写漏了。

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