Android, how to blur/glass/frost current activity

Question

Basically

In an activity, I have a ListView. When I select an item, an transparent activity opens as a small box. When this box appears, you can still view the previous activities screen,

What I am trying to figure out is how to blur the previous screen like the image linked here (Ignore the UI, just look at the blurred grass area).

How is this possible?

Thank you for any advice.

Answer 1

For API < 14, you could use the flag WindowManager.LayoutParams.FLAG_BLUR_BEHIND, but it's been deprecated and built-in blurring is no longer supported on higher APIs

However, you could do this with a regular view or overlay. What you want to do is:

• Create a Bitmap from your activity's overall layout (see here for example)
• Blur that bitmap with whatever method you want(a few examples here)
• Add(or unhide) a View in your layout that covers everything. Set bkg to blurred Bitmap
• Open your dialog/transparent activity
• When it closes, either remove the View, or setVisibility(GONE) if you'll be using it again.