Re: [AD] Not freeing resources of non-preserved bitmaps on Android is considered harmful :)

[Thomas Fjellstrom <thomas@xxxxxxxxxx>]

On Thu 22 Oct 2015 11:05:03 AM Max Savenkov wrote:
> 22.10.2015 11:00, Trent Gamblin пишет:
> > On October 22, 2015 10:40:56 AM Max Savenkov wrote:
> >> I think I found another bug in Android implementation. For some reason,
> >> in 'android_acknowledge_drawing_halt(ALLEGRO_DISPLAY *dpy)' Allegro does
> >> not delete resources of bitmap if it has ALLEGRO_NO_PRESERVE_TEXTURE
> >> flag set. Since in reality FBOs and textures for those bitmaps are
> >> deleted when OpenGL context is deleted during suspension, this leads to
> >> corruption after the game is resumed. I'm not very clear on details, but
> >> somehow OTHER bitmaps may end up corrupted because of this.
> >> 
> >> I tried commenting out this flag and it seems to make everything better
> >> 
> >> :) So unless there is some remembered reason for it being there, I
> >> 
> >> propose to strike out this check.
> > 
> > I'll check this tomorrow.
> 
> Great.
> 
> >> Also, I'd like to question the whole approach Allegro takes to
> >> suspension/resuming on Android. Why doesn't it uses the same method as
> >> SDL, which preserves the whole OpenGL context, instead of re-uploading
> >> bitmaps after resuming? This would eliminate the difference between
> >> NO_PRESERVE_TEXTRURE and other bitmaps (as it should be with OpenGL) and
> >> also preserve shaders (which presently has to be re-created as well
> >> during resuming). This would allow Allegro (or its user at least) to
> >> save memory by setting NO_PRESERVE_TEXTURE for all bitmaps and not store
> >> in-memory copy of data. Is there any reason not to do so, or is it just
> >> a historical decision?
> > 
> > If it's possible to preserve the context then NO_PRESERVE_TEXTURE should
> > be a no-op on Android like on PC. If you wish to create a patch for this
> > then I'll be happy to take a look at it.
> > 
> > Thanks.
> 
> Yes, it is possible, both SDL and Nya Engine (which we use at work for
> 3d) use this approach. I'll try to make a patch then, but it'll take
> some time. I'll post it if I succeed.

When the port was done, some devices with some versions of android just plain 
would lose the context and all data attached to it. And would lose it somewhat 
often. You couldn't actually tell it to keep the context. Everything was 
manual. If that's changed, great.

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-- 
Thomas Fjellstrom
thomas@xxxxxxxxxx