我想向 UIImage
添加褪色阴影/外发光/UIImageView
/UIView
但我不知道Core Graphics
根本不。
编辑: 请帮忙!!
最佳答案
采用 Cirrostratus 概述的方法,保留其缓存副本,然后在拖动时应用变换来更改图像的大小和/或位置。
(警告,这不是功能/测试代码,但应该可以帮助您入门)
-(UIImage*)addGlowToImage:(UIImage*)imageInput;
{
CGRect newSize = imageInput.bounds;
CGImageRef theImage = imageInput.CGImage;
// expand the size to handle the "glow"
newSize.size.width += 6.0;
newSize.size.height += 6.0;
UIGraphicsBeginImageContext(newSize);
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextBeginTransparencyLayerWithRect(ctx, newSize, NULL);
CGContextClearRect(ctx, newSize);
// you can repeat this process to build glow.
CGContextDrawImage(ctx, newSize, theImage);
CGContextSetAlpha(ctx, 0.2);
CGContextEndTransparencyLayer(ctx);
// draw the original image into the context, offset to be centered;
CGRect centerRect = inputImage.bounds;
centerRect.origin.x += 3.0;
centerRect.origin.y += 3.0;
CGContextDrawImage(ctx, centerRect, theImage);
result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
然后在您的方法中,在缩放时您会执行以下操作:
// assumes UIImage *cachedImage = [self addGlowToImage:origImage]; has been called already.
// assumes ivars for scale exists
CGRect newRect = cachedImage.bounds;
newRect.size.width += scale;
newRect.size.height += scale;
[cachedImage drawInRect:newRect]; // image will be scaled to fill destination rectangle.
一定要看看苹果文档。一个好的起点是 Quartz 2D Programming Guide .
关于iphone - 如何向 UIImage 或 UIImageView 或 UIView 添加外部发光,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/2278440/