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

[CodeSlaveZhang]

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]; } }

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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。