Using a rounded corners drawable

Question

There is a nice post made by the popular Google developer Romain Guy that shows how to use a rounded corners drawable (called "StreamDrawable" in his code ) on a v

Answer 1

There underlying problem is that the BitmapShader's TileMode doesn't have a scaling option. You'll note in the source that it's been set to Shader.TileMode.CLAMP, and the docs describe that as:

replicate the edge color if the shader draws outside of its original bounds

To work around this, there are three solutions:

1. Constrain the size of the view in which the drawable is used to the size of the bitmap.

2. Constrain the drawing region; for instance, change:

   int width = bounds.width() - mMargin;
   int height = bounds.height() - mMargin;
   mRect.set(mMargin, mMargin, width, height);
   

   To:

   int width = Math.min(mBitmap.getWidth(), bounds.width()) - mMargin;
   int height = Math.min(mBitmap.getHeight(), bounds.height()) - mMargin;
   mRect.set(mMargin, mMargin, width, height);
   

3. Scale the bitmap to the size of the drawable. I've moved creating the shader into onBoundsChange() and have opted to create a new bitmap from here:

   bitmap = Bitmap.createScaledBitmap(mBitmap, width, height, true);
   mBitmapShader = new BitmapShader(bitmap,
           Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
   

   Note that this a potentially slow operation and will be running on the main thread. You might want to carefully consider how you want to implement it before you go for this last solution.