protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    rectF.set(20, 20, this.get_Width() - this.get_Width()/10, this.get_Width() - this.get_Width()/10);
    RadialGradient gradient = new RadialGradient(200, 200, 200, 0xFFFFFFFF,
            0xFF000000, android.graphics.Shader.TileMode.CLAMP);
    Paint mPaint = new Paint();
    mPaint.setDither(true);
    mPaint.setShader(gradient);
    canvas.drawCircle(getWidth()/2, getHeight()/2, getWidth()/3, getGradient());
    invalidate();
}

@Override
public void onAttachedToWindow() {
   super.onAttachedToWindow();
   Window window = getWindow();
   // Eliminates color banding
   window.setFormat(PixelFormat.RGBA_8888);
}

Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);