put disk access into background thread?

[yulin2]

Hi, I'm doing research on performance for Android apps. I found some event handlers access disk (read/write files, decode bitmap) from UI thread, but Android docs suggest us to avoid such blocking calls in UI thread. Do they lead to any responsiveness issues?

I tried to refactoring by putting them into background tasks. Looking forward to see your comments.

[yulin2]

I sent this pr several days ago. Any idea/comments?

[brk3]

@yulin2 Sorry for the delay, Github didn't seem to notify me for some reason so never noticed your PR! Looks ok so far, have you noticed any performance increases from this? I'll do some tests this evening.

[brk3]

Missing import for Bitmap

[yulin2]

Thanks for the reply. I didn't measure performance increase from these refactorings. I apply them based Android docs' suggestion: blocking I/O calls (db, disk, bitmap decode) should be in background thread.

I manually tested the changes but didn't get that exception before. That exception is due to data races on "mPhotos" field. onPageSelected is executed before the initialization in onPostExecute. I remove the changes in PhotoViewerActivity.java to avoid such races.

Sorry for the missing import and final keyword. It's because I typed and committed via the Github web interface so I miss them. Now I added them. I may also create a cleaner pr if you think the changes are ok.