typedef NS_OPTIONS(NSInteger, NSStringDrawingOptions) { NSStringDrawingUsesLineFragmentOrigin = 1 << 0, // 整个文本将以每行组成的矩形为单位计算整个文本的尺寸 // The specified origin is the line fragment origin, not the base line origin NSStringDrawingUsesFontLeading = 1 << 1, // 使用字体的行间距来计算文本占用的范围,即每一行的底部到下一行的底部的距离计算 // Uses the font leading for calculating line heights NSStringDrawingUsesDeviceMetrics = 1 << 3, // 将文字以图像符号计算文本占用范围,而不是以字符计算。也即是以每一个字体所占用的空间来计算文本范围 // Uses image glyph bounds instead of typographic bounds NSStringDrawingTruncatesLastVisibleLine // 当文本不能适合的放进指定的边界之内,则自动在最后一行添加省略符号。如果NSStringDrawingUsesLineFragmentOrigin没有设置,则该选项不生效 // Truncates and adds the ellipsis character to the last visible line if the text doesn't fit into the bounds specified. Ignored if NSStringDrawingUsesLineFragmentOrigin is not also set. }
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