android transparent blur

I need to make an activity that will draw on the home screen, actually I simulate that part by making the background transparent to make that effect, but the problem is that I need to blur a geometric area around the touch coordinates, id needs to be a blurry circle with normal text over the blur, I know how to make what I need with semi transparent area but it needs to be made with custom blur (gaus开发者_JS百科sian), but not just a screenshot with blurred part, but an active desktop, so the blur is like, just a mask over the transparent background of the activity