I am trying to add a drop shadow to a UImageView

Question

I am trying to add a drop shadow to a UIImage view. I get a shadow but it is clipped to the edges of the image view and I am not sure why since I correctly set the uiimageview.clipsToBounds to NO. Below is the code:

-(void)addShadow
{
   UIGraphicsBeginImageContext(self.frame.size);
   CGContextRef myContext =  UIGraphicsGetCurrentContext();
   float           myColorValues[] = {0, 0, 0, darkness};// 3
   CGColorRef      myColor;// 4
   CGColorSpaceRef myColorSpace;
   CGContextSaveGState(myContext);// 6

   myColorSpace = CGColorSpaceCreateDeviceRGB ();// 9
   myColor = CGColorCreate (myColorSpace, myColorValues);// 10
   CGContextSetShadowWithColor (myContext, myShadowOffset, spread, myColor);// 11
   // Your drawing code here// 12
   // CGContextDrawImage(myContext, rotatingView.frame,imgRef);

   rotatingView.clipsToBounds = NO;
   [rotatingView.image drawInRect:rotatingView.frame
                        blendMode:kCGBlendModeNormal alpha:.5];
   CGColorRelease (myColor);// 13
   CGColorSpaceRelease (myColorSpace); // 14

   UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext();
   CGContextRestoreGState(myContext);
   UIGraphicsEndImageContext();
   rotatingView.image = imageCopy;
}

Drury

Answer 1

I believe the CGContextRef you're passed also has clipping set, to prevent basically this exact behavior. You might want to try just adding a CALayer:

CALayer                         *layer = [CALayer layer];
CGRect                          bounds = self.bounds;

layer.bounds = bounds;
layer.position = CGPointMake(bounds.size.width / 2 + 5, bounds.size.height / 2 + 5);
layer.backgroundColor = [UIColor colorWithWhite: 0.10 alpha: 0.75].CGColor;
layer.zPosition = -5;

[self.layer addSublayer: layer];

Fox

I tried adding this code but I still end up with clipped shadows. – Drury

Am I doing something else wrong in adding the code as above? or is the layer suppose to be the shadow? – Drury

The layer is supposed to be the shadow. You did set clipsToBounds to NO still? – Fox

Ah I see. clipstobounds is set to no. The problem with the layer is that it produces a square shadow with no blue, under a UIImage with any given shape. I was trying to apply the shadow directly to the UIImage. – Drury

ah, there's no easy way to do this. You'll basically have to do a custom shadow, and while there are several ways to do it, none of 'em are trivial to implement. – Fox

make sure you #import "QuartzCore/CALayer.h" – Unroll