CoreText.framework --- 图文混排

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：