[android-developers] Determine when view/views below my view have changed

Hello All,

I'm in the midst of implementing somewhat dynamic background blur effect for Android (similar to what iOS7 has) and I'm keen to have this one optimisation in place.

In my implementation I'm trying to achieve following:

1. I extend default layout classes and call them blur layouts

2. When view contents below blur layout in the view tree changes, I render what ever content there is into scaled offscreen bitmap (this is the part needing optimisation)

3. Blur is applied on offscreen bitmap using RenderScript implementation of stack blur

4. From then on the blur layout draws this blurred image as it's background

Now.. Currently.. I'm using ViewTreeObserver to determine when current screen is about to update (OnPreDrawListener) but this doesn't give me any indication whether content below my layout has changed. It's triggered no matter what update happens on the screen and though I'm recreating the blur image way too often - also in cases content below hasn't changed.

It would be great if someone with better knowledge on Android drawing internals could help me out on this one. Say, if my layout occupies Rect(100, 100, 200, 200) on the screen, I would like to observe in this layout when content below within it's area has changed. Or is this even possible?

For interested ones current implementation can be found here:

https://github.com/harism/android_anndblur

And precompiled application should appear in Play Market at some point.

--

Harri

--
You received this message because you are subscribed to the Google
Groups "Android Developers" group.
To post to this group, send email to android-developers@googlegroups.com
To unsubscribe from this group, send email to
android-developers+unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/android-developers?hl=en
---
You received this message because you are subscribed to the Google Groups "Android Developers" group.
To unsubscribe from this group and stop receiving emails from it, send an email to android-developers+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.