Android LiveWallpaper: load and draw various bitmaps efficiently (example: video)

Question

I am developing a live wallpaper that reproduces an animation (like a short video) on background.

Does anyone know how to efficiently load various full screen size bitmaps and draw them on canvas? I have tried 2 approaches and both are not very good.

Approach #1: Load all bitmaps on wallpaper startup.

Problem: Memory excess limit (about 35MB) cant load more than 10 bitmaps. So animations lack of different images.

Approach #2: Load only 2 bitmaps. On run time, paint bitmap, delete old bitmap, load new bitmap, repeat.

Problem: Consumes a lot of the system, (not memory, but slows down os in general), however it works because it doesn't exceed memory limit. But still, slows down the entire system.

example:

  Drawer.drawAll(res,c,p);
  res.removeOldBitmaps();
  res.loadNewBitmaps(wpservice,display);

A different approach i thought about is load resource on a separete thread, what do you guys think of that? do you have any other solutions?

Cheers!

You could do with one Bitmap only too. This could be achieved if you preload images into memory as byte arrays (png compressed for example) and decode only one at a time. Should this speed up the decoding process a bit compared to loading from resources at least. But if you're into video alike outcome why not make a video and use MediaPlayer? — harism, Jan 10 '13 at 18:01
Hey, that's a good idea, i will try it out and see if there are any improvements. No, i cant use media player on a live wallpaper, i dont know if it is possible, and even if it is, i plan to do some animations. Thanks for the response. — chelo_c, Jan 10 '13 at 18:05
Here i found a similar post with an intersteing question, however i havent tried it yet:http://stackoverflow.com/questions/10133306/android-live-wallpaper-animation [link](http://stackoverflow.com/questions/10133306/android-live-wallpaper-animation) — chelo_c, Jan 10 '13 at 18:07
Just in case you get interested in trying out the MediaPlayer approach, it's doable with OpenGL ES 2.0 and SurfaceTexture (API 11+ only though) at least. Without OpenGL I have no idea is it possible to have MediaPlayer render its contents on wallpaper surface. — harism, Jan 10 '13 at 18:10
Ohh thanks, i will take a look. However i wanted the wallpaper to work from API 9. — chelo_c, Jan 10 '13 at 18:36

score 0 · Accepted Answer · answered Jan 19 '13 at 15:35

Solved, the solution I found was the following:

Load images on runtime, 1 by 1.

And use this options:

/**Effective image decoder by chelin**/
public static Bitmap decodeResource(WallpaperService wpservice,int id){

    int scale=1;
    Resources res = wpservice.getResources();
    BitmapFactory.Options o2 = new BitmapFactory.Options();
    o2.inPreferredConfig = Bitmap.Config.ARGB_8888;
    o2.inSampleSize=scale;
    o2.inPurgeable = true;
    o2.inInputShareable = true;
    return BitmapFactory.decodeResource(res, id, o2);
}

Hope it works as it worked for me. Cheers!

If you don't care about transparency you can save memory by using Bitmap.Config.RGB_565 — James, Sep 18 '14 at 14:38

Android LiveWallpaper: load and draw various bitmaps efficiently (example: video)

1 Answers1