How to make an ImageView with rounded corners?

Question

In Android, an ImageView is a rectangle by default. How can I make it a rounded rectangle (clip off all 4 corners of my Bitmap to be rounded rectangles) in the ImageView?

Answer 1

While the above answer works, Romain Guy (a core Android developer) shows a better method in his blog which uses less memory by using a shader not creating a copy of the bitmap. The general gist of the functionality is here:

BitmapShader shader;
shader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);

Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setShader(shader);

RectF rect = new RectF(0.0f, 0.0f, width, height);

// rect contains the bounds of the shape
// radius is the radius in pixels of the rounded corners
// paint contains the shader that will texture the shape
canvas.drawRoundRect(rect, radius, radius, paint);

The advantages of this over other methods is that it:

• does not create a separate copy of the bitmap, which uses a lot of memory with large images [vs most of the other answers here]
• supports antialisasing [vs clipPath method]
• supports alpha [vs xfermode+porterduff method]
• supports hardware acceleration [vs clipPath method]
• only draws once to the canvas [vs xfermode and clippath methods]

I've created a RoundedImageView based off this code that wraps this logic into an ImageView and adds proper ScaleType support and an optional rounded border.