核心文本/ NSStringDrawing - CFAttributedStringRef/NSAttributedString - 更改字体大小

Question

案例：属性字符串已创建。如何改变字符串的大小？

我猜我们既可以

A）更新的pointsize所有字体的属性串

B）绘制属性串一些变换

Answer 1

能正常工作在Mac OS和iOS

@implementation NSAttributedString (Scale) 

- (NSAttributedString *)attributedStringWithScale:(double)scale 
{ 
    if(scale == 1.0) 
    { 
     return self; 
    } 

    NSMutableAttributedString *copy = [self mutableCopy]; 
    [copy beginEditing]; 

    NSRange fullRange = NSMakeRange(0, copy.length); 

    [self enumerateAttribute:NSFontAttributeName inRange:fullRange options:0 usingBlock:^(UIFont *oldFont, NSRange range, BOOL *stop) { 
     double currentFontSize = oldFont.pointSize; 
     double newFontSize = currentFontSize * scale; 

     // don't trust -[UIFont fontWithSize:] 
     UIFont *scaledFont = [UIFont fontWithName:oldFont.fontName size:newFontSize]; 

     [copy removeAttribute:NSFontAttributeName range:range]; 
     [copy addAttribute:NSFontAttributeName value:scaledFont range:range]; 
    }]; 

    [self enumerateAttribute:NSParagraphStyleAttributeName inRange:fullRange options:0 usingBlock:^(NSParagraphStyle *oldParagraphStyle, NSRange range, BOOL *stop) { 

     NSMutableParagraphStyle *newParagraphStyle = [oldParagraphStyle mutableCopy]; 
     newParagraphStyle.lineSpacing *= scale; 
     newParagraphStyle.paragraphSpacing *= scale; 
     newParagraphStyle.firstLineHeadIndent *= scale; 
     newParagraphStyle.headIndent *= scale; 
     newParagraphStyle.tailIndent *= scale; 
     newParagraphStyle.minimumLineHeight *= scale; 
     newParagraphStyle.maximumLineHeight *= scale; 
     newParagraphStyle.paragraphSpacing *= scale; 
     newParagraphStyle.paragraphSpacingBefore *= scale; 

     [copy removeAttribute:NSParagraphStyleAttributeName range:range]; 
     [copy addAttribute:NSParagraphStyleAttributeName value:newParagraphStyle range:range]; 
    }]; 

    [copy endEditing]; 
    return copy; 
} 

@end 

快乐编码

Answer 2

我相信在解析是唯一的出路。归属字符串的格式可能非常复杂，您的工作是增加字体大小。

但是，如果您需要这种渲染技巧，您可以避免字符串解析 - 使用缩放变换来增加文本大小。

Answer 3

我使用下面的代码。其中一个错误是，如果属性字符串中的某些文本没有被设置为字体属性，它将不会被更新。所以我不得不用font-attributes来封装所有东西。

- (void)recalculateSizeChangeInAttributedString { 

    if(self.attributedStringOriginal == nil) { 
     self.attributedStringOriginal = [self.attributedString copy]; 
    } 

    CFMutableAttributedStringRef tempString = CFAttributedStringCreateMutableCopy(CFAllocatorGetDefault(), self.attributedStringOriginal.length, (CFMutableAttributedStringRef)self.attributedStringOriginal); 

    int lastIndex = 0; 
    int limit = CFAttributedStringGetLength(tempString); 
    for (int index = 0; index < limit;) { 

     CFRange inRange = CFRangeMake(0, limit - index); 
     CFRange longestEffective; 
     CTFontRef font = (CTFontRef)CFAttributedStringGetAttribute(tempString, index, kCTFontAttributeName, &longestEffective); 

     if(font != nil) { 

      // log for testing 
      NSLog(@"index: %i, range: %i - %i, longest: %i - %i, attribute: %@", 
        index, inRange.location, 
        inRange.location + inRange.length, 
        longestEffective.location, longestEffective.location + longestEffective.length, 
        @"..." 
       ); 


      // alter the font and set the altered font/attribute 
      int rangeEnd = longestEffective.length != 0 ? longestEffective.length : 1; 
      CTFontRef modifiedFont = CTFontCreateCopyWithAttributes(font, CTFontGetSize((CTFontRef)font) * sizeFactor, NULL, NULL); 
      CFAttributedStringSetAttribute(tempString, CFRangeMake(index, rangeEnd), kCTFontAttributeName, modifiedFont); 
      CFRelease(modifiedFont); 

     } 

     // make next loop continue where current attribute ended 
     index += longestEffective.length; 

     if(index == lastIndex) 
      index ++; 
     lastIndex = index; 

    } 

    self.attributedString = (NSMutableAttributedString *)tempString; 

    CFRelease(tempString); 

}