为什么我的文字没有在视网膜显示屏上正确绘制

Question

我正在尝试绘制一些文字，并且在非视网膜显示器上很好，但在视网膜显示器上它不是高分辨率。

这是我的iPad Air截图：

请参阅下面的代码，它实际上将文本绘制为半透明，周围几乎不透明，因此您可以通过文本查看图像。

-(void) maskImage:(UIImageView *)imageView withText:(NSString *)text font:(UIFont *)font attributes:(NSDictionary *)attributes yOffset:(CGFloat)yOffset 
{ 
  NSStringDrawingContext *paraContext = [[NSStringDrawingContext alloc] init];
  NSStringDrawingOptions stringDrawingOptions = NSStringDrawingUsesLineFragmentOrigin|NSStringDrawingTruncatesLastVisibleLine;

  // find out how much space we need for the text
  CGSize textSize = CGSizeIntegral([text boundingRectWithSize:CGSizeMake(kNowPlayingTrackDetailsMaxWidth, kNowPlayingTrackDetailsMaxHeight) options:stringDrawingOptions attributes:attributes context:paraContext].size);

  // set up the frame for drawing the text, including some padding

  CGSize drawingSize = {textSize.width + 80, textSize.height + 60};
  CGRect drawingFrame = { 0, 0, drawingSize.width, drawingSize.height};
  CGRect textFrame = { 40, 30, textSize.width, textSize.height };

  UIGraphicsBeginImageContextWithOptions(drawingSize, YES, 0);

  UIColor *bgColor = [UIColor colorWithWhite:1 alpha:.98];
  [bgColor setFill];
  [bgColor setStroke];

  UIBezierPath *path = [UIBezierPath bezierPathWithRect:drawingFrame];
  [path fill];

  // draw the text

  [text drawWithRect:textFrame options:stringDrawingOptions attributes:attributes context:paraContext];
  UIImage *textImage = UIGraphicsGetImageFromCurrentImageContext();

  UIGraphicsEndImageContext();

  // now create an image mask from the text image

  CIImage *inputImage = [CIImage imageWithCGImage:textImage.CGImage];
  CIFilter *filter = [CIFilter filterWithName:@"CIMaskToAlpha" keysAndValues:kCIInputImageKey, inputImage, nil];
  CIImage *outputImage = [filter outputImage];

  imageView.image = [UIImage imageWithCIImage:outputImage];

  // final set the UIImageView size to match the drawing size
  CGRect imageViewFrame = imageView.frame;
  imageViewFrame.size = drawingSize;
  imageView.frame = imageViewFrame;
}

Answer 1

奥利弗·琼斯帮我解决了这个问题。谢谢@orj！

答案是用

创建UIImage

    [UIImage imageWithCIImage:outputImage scale:textImage.scale orientation:UIImageOrientationUp];

而不是

    imageView.image = [UIImage imageWithCIImage:outputImage];

这样可以正确设置输出图像的比例。