Calling to SciEngine::syncSoundSettings from GuestAdditions
recurses back into GuestAdditions, which is obviously not
desirable. Even when it didn't manage to cause infinite recursion
(as in SQ6 demo), it would make the UI behave in broken ways (e.g.
the +/- buttons on the music slider in SQ6 would not work because
the UI would just get updated immediately back to the closest
rounded value).
Export functions may be relocated above 64k in SCI3, but exports
that do not have an entry in the relocation table must be handled
the same as SCI1.1-2.1.
This patch includes enhancements to the ScummVM integration with
SCI engine, with particular focus on SCI32 support.
1. Fixes audio volumes syncing erroneously to ScummVM in games
that modify the audio volume without user action (e.g. SCI1.1
talkies that reduce music volume during speech playback). Now,
volumes will only be synchronised when the user interacts with
the game's audio settings. This mechanism works by looking for
a known volume control object in the stack, and only syncing
when the control object is present. (Ports and planes were
researched and found unreliable.)
2. Fixes audio syncing in SCI32 games that do not set game
volumes through kDoSoundMasterVolume/kDoAudioVolume, like GK1,
GK2, Phant1, and Torin.
3. Fixes speech/subtitles syncing in SCI32 games that do not use
global 90, like LSL6hires.
4. Fixes in-game volume controls in SCI32 games reflecting
outdated audio volumes when a change is made during the game
from the ScummVM launcher.
5. Fixes SCI32 games that would restore volumes from save games
or reset volumes on startup, which caused game volumes to be
out-of-sync with ScummVM when started.
6. ScummVM integration code for audio sync has been abstracted
into a new GuestAdditions class. This keeps the ScummVM-
specific code all in one place, with only small hooks into the
engine code. ScummVM integrated save/load code should probably
also go here in the future.
Fixes Trac#9700.
