IOS 图文混排（CoreText.framework）详解及实例

IOS 图文混排（CoreText.framework）

       本文主要介绍了IOS图文混排的资料，这里整理了在网上查找的内容，帮助理解，掌握这部分知识，以下就是整理的内容：

利用CORETEXT进行图文混排。

实现代码：

void RunDelegateDeallocCallback( void* refCon ){ 

} 

CGFloat RunDelegateGetAscentCallback( void *refCon ){
  NSString *imageName = (NSString *)refCon;
  return 80;//[UIImage imageNamed:imageName].size.height;
} 

CGFloat RunDelegateGetDescentCallback(void *refCon){
  return 0;
} 

CGFloat RunDelegateGetWidthCallback(void *refCon){
  NSString *imageName = (NSString *)refCon;
  return 100;//[UIImage imageNamed:imageName].size.width;
} 

先设置一个CTRun的委托，主要是用于指定对象的上行高，宽，或上下文释放时使用。

-(void)drawCharAndPicture
{
  CGContextRef context = UIGraphicsGetCurrentContext(); 

  CGContextSetTextMatrix(context, CGAffineTransformIdentity);//设置字形变换矩阵为CGAffineTransformIdentity，也就是说每一个字形都不做图形变换 

  CGAffineTransform flipVertical = CGAffineTransformMake(1,0,0,-1,0,self.bounds.size.height);
  CGContextConcatCTM(context, flipVertical);//将当前context的坐标系进行flip
  NSLog(@"bh=%f",self.bounds.size.height); 

  NSMutableAttributedString *attributedString = [[[NSMutableAttributedString alloc] initWithString:@"请在这里插入一张图片位置"] autorelease]; 

  //为图片设置CTRunDelegate,delegate决定留给图片的空间大小
  NSString *imgName = @"img.png";
  CTRunDelegateCallbacks imageCallbacks;
  imageCallbacks.version = kCTRunDelegateVersion1;
  imageCallbacks.dealloc = RunDelegateDeallocCallback;
  imageCallbacks.getAscent = RunDelegateGetAscentCallback;
  imageCallbacks.getDescent = RunDelegateGetDescentCallback;
  imageCallbacks.getWidth = RunDelegateGetWidthCallback;
  CTRunDelegateRef runDelegate = CTRunDelegateCreate(&imageCallbacks, imgName);
  NSMutableAttributedString *imageAttributedString = [[NSMutableAttributedString alloc] initWithString:@" "];//空格用于给图片留位置
  [imageAttributedString addAttribute:(NSString *)kCTRunDelegateAttributeName value:(id)runDelegate range:NSMakeRange(0, 1)];
  CFRelease(runDelegate); 

  [imageAttributedString addAttribute:@"imageName" value:imgName range:NSMakeRange(0, 1)]; 

  [attributedString insertAttributedString:imageAttributedString atIndex:4]; 

 //换行模式
  CTParagraphStyleSetting lineBreakMode;
  CTLineBreakMode lineBreak = kCTLineBreakByCharWrapping;
  lineBreakMode.spec = kCTParagraphStyleSpecifierLineBreakMode;
  lineBreakMode.value = &lineBreak;
  lineBreakMode.valueSize = sizeof(CTLineBreakMode); 

  CTParagraphStyleSetting settings[] = {
    lineBreakMode
  }; 

  CTParagraphStyleRef style = CTParagraphStyleCreate(settings, 1); 

  // build attributes
  NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithObject:(id)style forKey:(id)kCTParagraphStyleAttributeName ]; 

  // set attributes to attributed string
  [attributedString addAttributes:attributes range:NSMakeRange(0, [attributedString length])]; 

  CTFramesetterRef ctFramesetter = CTFramesetterCreateWithAttributedString((CFMutableAttributedStringRef)attributedString); 

  CGMutablePathRef path = CGPathCreateMutable();
  CGRect bounds = CGRectMake(0.0, 0.0, self.bounds.size.width, self.bounds.size.height);
  CGPathAddRect(path, NULL, bounds); 

  CTFrameRef ctFrame = CTFramesetterCreateFrame(ctFramesetter,CFRangeMake(0, 0), path, NULL);
  CTFrameDraw(ctFrame, context); 

  CFArrayRef lines = CTFrameGetLines(ctFrame);
  CGPoint lineOrigins[CFArrayGetCount(lines)];
  CTFrameGetLineOrigins(ctFrame, CFRangeMake(0, 0), lineOrigins);
  NSLog(@"line count = %ld",CFArrayGetCount(lines));
  for (int i = 0; i < CFArrayGetCount(lines); i++) {
    CTLineRef line = CFArrayGetValueAtIndex(lines, i);
    CGFloat lineAscent;
    CGFloat lineDescent;
    CGFloat lineLeading;
    CTLineGetTypographicBounds(line, &lineAscent, &lineDescent, &lineLeading);
    NSLog(@"ascent = %f,descent = %f,leading = %f",lineAscent,lineDescent,lineLeading); 

    CFArrayRef runs = CTLineGetGlyphRuns(line);
    NSLog(@"run count = %ld",CFArrayGetCount(runs));
    for (int j = 0; j < CFArrayGetCount(runs); j++) {
      CGFloat runAscent;
      CGFloat runDescent;
      CGPoint lineOrigin = lineOrigins[i];
      CTRunRef run = CFArrayGetValueAtIndex(runs, j);
      NSDictionary* attributes = (NSDictionary*)CTRunGetAttributes(run);
      CGRect runRect;
      runRect.size.width = CTRunGetTypographicBounds(run, CFRangeMake(0,0), &runAscent, &runDescent, NULL);
      NSLog(@"width = %f",runRect.size.width); 

      runRect=CGRectMake(lineOrigin.x + CTLineGetOffsetForStringIndex(line, CTRunGetStringRange(run).location, NULL), lineOrigin.y - runDescent, runRect.size.width, runAscent + runDescent); 

      NSString *imageName = [attributes objectForKey:@"imageName"];
      //图片渲染逻辑
      if (imageName) {
        UIImage *image = [UIImage imageNamed:imageName];
        if (image) {
          CGRect imageDrawRect;
          imageDrawRect.size = image.size;
          imageDrawRect.origin.x = runRect.origin.x + lineOrigin.x;
          imageDrawRect.origin.y = lineOrigin.y;
          CGContextDrawImage(context, imageDrawRect, image.CGImage);
        }
      }
    }
  } 

  CFRelease(ctFrame);
  CFRelease(path);
  CFRelease(ctFramesetter);
} 

效果：

从上面看大家可能没有发现什么问题，当把图片放在字的最左边会是什么样子的？

因此为了避免这种情况发生，我在代码中添加了换行模式。添加换行后的效果：

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