能否向UIImage / UIImageView添加另一个较小的图像?如果可以,怎么做?如果不行,那么如何绘制一个小的填充三角形?
谢谢。
能否向UIImage / UIImageView添加另一个较小的图像?如果可以,怎么做?如果不行,那么如何绘制一个小的填充三角形?
谢谢。
您可以将一个包含小实心三角形的图像添加为您的 UIImageView
的子视图。或者您可以在第一幅图像内绘制:
CGFloat width, height;
UIImage *inputImage; // input image to be composited over new image as example
// create a new bitmap image context at the device resolution (retina/non-retina)
UIGraphicsBeginImageContextWithOptions(CGSizeMake(width, height), YES, 0.0);
// get context
CGContextRef context = UIGraphicsGetCurrentContext();
// push context to make it current
// (need to do this manually because we are not drawing in a UIView)
UIGraphicsPushContext(context);
// drawing code comes here- look at CGContext reference
// for available operations
// this example draws the inputImage into the context
[inputImage drawInRect:CGRectMake(0, 0, width, height)];
// pop context
UIGraphicsPopContext();
// get a UIImage from the image context- enjoy!!!
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
// clean up drawing environment
UIGraphicsEndImageContext();
这段代码(源代码在此)可以创建一个新的UIImage
,你可以用它来初始化一个UIImageView
。
你可以尝试这个,对我来说效果非常完美,它是UIImage类别:
- (UIImage *)drawImage:(UIImage *)inputImage inRect:(CGRect)frame {
UIGraphicsBeginImageContextWithOptions(self.size, NO, 0.0);
[self drawInRect:CGRectMake(0.0, 0.0, self.size.width, self.size.height)];
[inputImage drawInRect:frame];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
或者Swift:
extension UIImage {
func image(byDrawingImage image: UIImage, inRect rect: CGRect) -> UIImage! {
UIGraphicsBeginImageContext(size)
draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
image.draw(in: rect)
let result = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return result
}
}