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TODO

Revision as of 17:02, 13 March 2018 by BgK (talk | contribs) (Remove iterator handling from the todo list. It is too much of a pitfall for GSoC students.)
TODO List
Name Main TODO List
Technical Contact(s) The ScummVM Team
Subsystem Generic

Here is a list of things we consider doing in the future. Note that we don't promise to do any of these, nor when we will do them. It's just a list of what we hope to be able to do one day, and some items on the list really are more like ideas than real proposals, so take it with a grain of salt.

If you want to dig in, this is the stuff where you might make the most useful contribution. Note that this list is never complete, and may be partially outdated, so just because you don't see something here doesn't mean it is not important.

Before you start work on something, you should first talk to the team! Ideally ask on scummvm-devel, our mailing list. This will help us to prevent double work, i.e. several people working on the same stuff at once without knowing about each other. Furthermore, sometimes entries on our list are actually obsolete (because the feature has been implemented, or because for some reason we no longer think it to be desirable). Special caution should be taken for TODO entries that say "we may want to" or similar things; that usually means that we aren't sure whether we really want to implement that feature.

So, to repeat it: Always talk to the team before implementing a change on this list, or else risk having your patch rejected :-/.

Finally, always make sure to check out our bug tracker and our feature request tracker for things that need work.


Documentation

See also the Documentation/TODO page.

General

  • Add port specific user documentation (dreamcast/palm especially). That would include things like:
    • How to use ScummVM on system XYZ
  • Update/enhance man page
  • Write a high level overview of how ScummVM and its engines work?

README / Manual

  • A proper manual might be nice.
  • Maybe move all/most of the compression related stuff from our README completely to the tools README, and only leave a pointer to that in the main README. This would be beneficial because this way, it's only documented in one place; it's *completly* documented (currently, the main README doesn't mention compress_scumm_bun, for example); and people who want to use the compression tools need to download the tools package anyway.
  • It would be greate to have a "Developer's Guide to ScummVM" which explains the ScummVM framework, and also the engines, i.e.
    • stuff in common/, like the config manager etc.
    • the backend API, and how to create new backends
    • the sound system
    • how to create a new engine
    • a chapter for each engine, with as many/little details as the resp. engine teams deem appropriate...
    • ...

Web sites

Primary website

  • Add big (green?) shiny buttons in the middle of the page for (1) Donations and (2) Downloads ?
  • Show "Release Date" on download page
  • Change all screenshot filenames to match our rules as described here. E.g. rename data/screenshots/agos/simon/scummvm_2_4_0.jpg to data/screenshots/agos/simon/simon-0.jpg etc.; also some stuff should maybe be moved to other directories.

Buildbot

  • Track the size of the resulting binaries.
    • This would greatly help in tracking down when and why the size of the ScummVM binary increased.
    • Doing this should not be hard. Setup a database which stores for each commit the size of the (stripped) binary of each port.
    • Then, add a way to query that database via a webfront. At first, simply dumping all the numbers would be good enough. On the long run, it would be nice to show some cool graphical diagrams.
    • For bonus points, allow the user of that webpage to dynamically change it using javascript: i.e. selecting which ports to show, which range of revisions; mousing over a data point shows a little box with details on the commit; clicking on a revision number jumps to the corresponding page in our SVN repository viewer; etc. ;).
  • Install the new required dependencies (libpng and libtheora for Sword25) into the cross compiler environments of all ports that have a chance of supporting Sword25.
  • Install the new required dependencies (libpng, libfreetype, boost and wx-widgets) into the cross compiler environments of all desktop ports to support building of tools.

Doxygen

  • Create a visual theme which matches that of our forum and website

Forums

  • Upgrade to phpBB 3. This receives security updated, and would provide many new handy features for users and admins alike. The main issue here is that somebody would have to rewrite our custom theme for that. Maybe we can hire somebody to do this?

Planet

  • Improve the visual theme to better match that of the forum and website

Wiki

  • Create a visual theme which matches that of our forum and website
  • Add content to Wanted Pages
  • Add some content to Help:Editing, which is shown when editing a page

Common code, infrastructure

General

  • Revise the way "quit" is handled. Maybe add a global variable "g_quit" which we set when the application should be quit (e.g. when an EVENT_QUIT is received). This is useful if multiple levels of event loops have to be ended
  • Make some generic "EventLoop" API/class which all backends and the GUI use. Initially this would just call the backend poll_event() etc. methods. But eventually the EventLoop object(s) could be made by the backend. This may allow for more efficient CPU usage etc. The current event handling model essentially is polling: the engines run some kind of main loop, which, besides many other things, also polls and dispatches events. The idea is to turn this around: the event loop frequently gives the engine time to do these "other things".
  • Maybe add ways to modify the game configs via the command line. E.g. allow
   ./scummvm --add new_target --path=/foo monkey2
   ./scummvm --remove new_target
  • The following things should be put into namespaces:
    • MIDI related classes either to Audio, or a new "MIDI" namespace
    • backend specific stuff into ??? (maybe new namespace "Backends" ?) not sure about this one.
  • Get rid of getenv in as many places as possible. Ideally, we'd only use it to query HOME on Unix systems.

Events

Event struct

The following is a (revision of) a former comment in common/events.h:

Rework/document this structure. It should be made 100% clear which field is valid for which event type. Implementation wise, we might want to use the classic union-of-structs trick. It goes roughly like this: 

struct BasicEvent {
    EventType type;
};
struct MouseMovedEvent : BasicEvent {
    Common::Point pos;
};
struct MouseButtonEvent : MouseMovedEvent {
    int button;
};
struct KeyEvent : BasicEvent {
    ...
};
...
union Event {
    EventType type;
    MouseMovedEvent mouse;
    MouseButtonEvent button;
    KeyEvent key;
    ...
};

However, this approach is contrary to classic OO paradigms. Indeed, its major drawback is that all event types now must be POD data types, so e.g. they can't contain a Common::Point as member. Bad.

An alternative approach would be a more OO like switch to multiple Event subclasses. This would, however, then require us to pass events around as pointers to object instances, and also would require introducing type casting in code using events. The passing around of pointers could be mitigated by using 

typedef Common::SharedPtr<BasicEvent> Event

or something like that. Yet this would mean increased overhead in all our code, yet the gain is unclear. In conclusion, we probably are best off by staying with the existing monolithic struct Event, we should just enhance its documentation.

Build System

  • Add test(s) for backend usability in the configure script.
  • Add an install target to the Makefile - Copy binary, install manpage, add menu items, install README. See also patch #891909 (Gnome/KDE .desktop file)
  • Investigate whether switching to CMake or SCons or some other cross platform configuration environment would work for us. Potential advantage: Less effort to maintain and extend the build system, automatic generation of various kinds of project files (Makefiles, and project files for MSVC, XCode, Eclipse, KDevelop ...). Potential drawback: Problems with the customized build systems of our various ports. However, the latter might actually be improved by using CMake or SCons -- hard to say without tests.

Audio

Mixer

  • Get the high quality resample code to work
  • Consider changing the mixer volume to use range 0-255, for sake of consistency (but at a slight loss of efficiency). Note that this requires changes in at least rate.cpp and mixer.cpp.
  • Some of our engines support the speech_mute / sfx_mute / music_mute options, but most don't. Almost all support the corresponding FOO_volume config keys. All engines use Mixer::setVolumeForSoundType to push those through to the mixer. I am wondering: Maybe it would make sense to remove Mixer::setVolumeForSoundType, and instead leave it up to the mixer to query the ConfigManager for the corresponding FOO_volume/_mute values? That way we'd ensure 100% identical behavior in all engines and actually simplify the code a bit... ? Not sure if this would work smoothly, it needs to be investigated.
  • the "isReady" code is irritating. Most engines ignore it anyway. It's primary purpose is to allow ScummVM to run even if not digitial audio out is available. A better solution would likely be to enforce that all backends always return a valid mixer. In the worst case, if a backend cannot produce audio output, it should still instantiate an Audio::MixerImpl, with some arbitrary sample rate (I recommend 22050 Hz), and a fake playback thread, which acts like an audio output callback but simply discards the generated audio data. (Note: It doesn't suffice to just throw away input data in Mixer::playInputStream, as this breaks with QueuingAudioStream).
  • document the semantics of sound handles and sound ids
  • Are there backends which could benefit from a 'custom' mixer? If so, what would be required to implement such a thing? Needs talking to porters

CD

  • Consider extending the Audio CD Manager with WAV or VOC support (essentially, the WAV/VOC code would need to be enhanced by adding a factory function similar to that provided for the FLAC/Vorbis/MP3 streams).
  • add a "pause" feature to the AudioCDManager (might require us to extend the OSystem CD API, too). Useful to be able to fully pause the currently running engine

MIDI

  • See also Music drivers redesign
  • MIDI: Add API to OSystem which allows client code to query for "native" MIDI drivers (like Windows, ALSA, Zodiac, CoreAudio). Then change the MIDI interfacing code (GUI, command line, config file, etc.) and also MidiDriver::createMidi() to use both that list and the list of 'emulated' MIDI devices (AdLib, MT-32, PC Speaker, etc.) in an appropriate way.
  • Make it possible to pass options to the midi/music drivers. This would allow us to get rid of the getenv hacks in the alsa & seq drivers.
    • A simple approach would be to allow the user to specify "extended" driver descriptions. E.g. "alsa:1234" could indicate the alsa driver with port 1234; alternatively, "alsa:port=1234".
    • This doesn't allow for easy tweaking of those settings via the GUI.... to achieve that, one approach would be to invent a 'parameter description language' which allows a driver to specify which options with which kind of values it supports... very flexible, but possibly overkill.
    • Instead, one could add a hook method to MIDI drivers that let's them add a few controls of their own to the options dialog. This is probably a lot easier to implement, though not quite as "clean"...
  • Our XMIDI parser seems to have a couple of missing features, but it's unclear which ones are actually needed. Possible references for a better implementation include the Exult project and the source code for AIL Version 2. The KYRA engine contains some more complete XMIDI implementation on top of our XMIDI parser class too, so it might also be a place to look at for reference.

Config Manager

  • Modify the ConfigManager to make use of the ConfigFile class. This is more difficult than it sounds at first, because currently our ConfigManager is not just used for managing the active config, but also ab-used for editing config data (once for specific targets, in the launcher's "edit game" dialog, and once for editing the "active config" in the engines/dialog.cpp ConfigDialog). This mess needs to be untangled first.
  • Maybe even follow the pentagram (http://pentagram.sf.net) approach and have three classes:
    • SettingsManager (like our current ConfigManager)
    • ConfigFileManager (manages a set of config files, possibly merging the data from multiple config files)
    • ConfigFile (a simple .ini file accessor).
    This makes it easy to add additional config sources (e.g. XMLConfigFile); makes it possible to treat the command line data like another config file (CommandLineConfig); and simply follows the good old MVC approach, which is always a good idea.
  • Add a proper version to the Config file, which indicates true changes in the format / data in it. Right now, we only have a "fake" version number where any ScummVM instance will just write its version in. Which is totally useless. A proper version would allow us to ...
    • ... produce a warning if an older ScummVM version tries to load a config file written by a newer version with potentially incompatible changes (such as the switch from language code "hb" to "he" for Hebrew)
    • ... detect when we an old config file is loaded which needs to be updated (e.g. by changing language "hb" to "he"; by adding "guioptions" to targets; by fixing trailing slashes in "path"; maybe even updating old style; and maybe in the future by adding "engineid" fields to all targets)

Files

  • Don't rely on the existence of SEEK_CUR, SEEK_END, SEEK_SET -- rather, define our own enum for this and convert all client code to use it.
  • Try to replace all usages of paths by FilesystemNode.

GUI

Plugins

  • On OSX: Support a plugin build in the bundle target: *.plugin files should be put into ScummVM.app/Contents/PlugIns/; this also means that the loader needs to search in the plugin dir of the active bundle. So use the CF bundle API, inside a #ifdef MACOSX block.
  • Make DetectedGame::updateDesc a normal function, not a member function.

Launcher

  • Enhance the Mass detector to show a list with the results (and optionally, allow the user to edit/cull that list before adding it).
  • Game edit dialog: Consider adding some warnings to the platform/language fields ("Don't mess with these unless you know what you are doing"), or move them to an "advanced" tab
  • Make the gameid editable via an "advanced" tab entry?
  • There is no way to reset the save/extra/theme paths. Adding a tiny button labeled "c" for clearing them (like for the soundfont path button) is not the way to solve this, I think. One approach would be to extend the Browser dialog, to allow an (optional) extra button, with customizable label. When pressed, the browser dialog closes and returns a special code. Well, and we'd use labels like "Use default savepath" or "Reset extrapath", or just always "Use default value".
  • The global options dialog may show a button for configuring the savepath even on systems where it is fixed -> not good. This button should be hidden/removed for these systems
  • separate launcher code even more from rest of ScummVM, to make custom launchers easier?
    • maybe separate launcher using MVC approach? Separate code which scans for games etc. from the presentation layer, to make it easier to write custom launchers with behavior matching that of the default launcher?
  • show cover art in launcher
    • this would only be done on "high end" systems, must be possible to disable code
    • we can't ship artwork directly, due to copyright concerns; so only ship artwork where it is legally possible, and otherwise allow users to setup "artwork packs"
    • control what artwork is shown using a config key

Global Main Menu/Return to Launcher

  • Confirm exit dialog woes:
    • Double "confirm exit" dialog: When confirm exit is enabled in ScummVM, the ScummVM quit confirm dialog shows up in addition to the quit confirm dialogs for those games which have their own. For example, when you select 'Quit' from Beneath a Steel Sky's in-game menu, it asks you if you really want to quit. Then, after answering, ScummVM gives you another dialog asking you if you really want to quit. So, ScummVM should not show the quit confirm dialog if the in-game dialog has already been displayed. This affects any game which has it's own menu system from where you can quit, or has a native quit confirm dialog. So this means most games.
    • Add/unify "confirm exit" dialog, globally (see FR #1731025)
  • Options Dialog: Implement engine flags to define which features in the Options dialog are supported by the current running game. Use these flags to hide/show the appropriate sliders and buttons in the Options Dialog
  • Allow engines to extend the GMM more freely. E.g. for the SCUMM engine, we would want to add a "Help" button. Alternatively, just always have a help button and only show/hide resp. en-/disable it as needed.
  • Improve the look of the GMM: This could include displaying the engine name and the ScummVM logo somewhere on the GMM.
  • Config Dialog code: Resolve the FIXME in engines/dialogs.cpp which pertains to having to use the empty string as the domain name. This is a bigger task, but will enable many other changes (thus as finally changing ConfigManager to use ConfigFile). Essentially, the current game config dialog tries to abuse the system by editing the *active* settings via the config manager, in order to fully reduce the options dialog code from the launcher. But there is a big difference between editing the config settings of a specific target, and the active settings. So, one probably needs to rewrite the code for the config dialog shown from the GMM
  • Make it possible to reach the "key remapper" and "virtual keyboard" from the GMM, if available?
  • Sugar on the cake: In addition to the ScummVM logo and version, how about showing the engine name and game title at the top of the GMM?

Error handling

Sometimes, bugs are reported that are not easily reproducible, e.g. Bug #6751. In such cases, it would be useful to have the error handler in ScummVM generate (and, optionally, automatically send) minidumps that can be used by us to successfully examine crashed ScummVM processes. Integration of something like Google Breakpad is one reasonable option. While it is not likely to be able to get such crash handling into all ports, just supporting the most popular platforms would be enough to make this feature very useful.

Engines / frontends

SCUMM

AGI

AGOS

Cine

CruisE

Drascula

Gob

Groovie

Hopkins

Hugo

Kyra

Lastexpress

MADE

Mohawk

Parallaction

SAGA

SCI

Broken Sword 1

  • Modify MoviePlayer class to use ManagedArray for _movieTexts.
  • Add support for Bink RDFT compressed audio in the Smacker videos (used in some later releases).

Broken Sword 2

  • Fix the credits so they look more like the original. (Did we ever get the source code for that?)
  • Maybe work around script bug which causes the mop to disappear briefly when trying to pick it up from the top of the boat at the London docks. (The event to hide the mop is sent too early.) [Bug #2058].
  • Maybe (but probably not) work around a graphics glitch where George can be drawn partially in front of a metal beam he's walking behind. (He's obscured properly by the beam sprite, but part of the beam is only background.) [Bug #4483].
  • Unify some of the code with Broken Sword 1 (e.g. in router.cpp).

Sword25

Tinsel

Tony

Toon

Touche

TsAGE

Tucker

Wintermute

Backends and ports

General

  • Add API to query backend for a list of available music engines. Useful for Options dialog. See Music drivers redesign.
  • Right now gBitFormat is part of common/scaler.cpp; we might want to move it to common/system.cpp, or replace it with something better. No hasty changes here, please, make sure you understand how it is used right now before messing with it ;-)

SDL backend

  • Right now, the WinCE and the Symbian backend subclasses the regular SDL backend. They both overload a lot of methods (mostly the graphics stuff). Since graphics.cpp uses the scalers (e.g. hq3x), these derived backends carry that baggage around, too, even though they don't need that code. Idea: split the SDL backend into two classes, one base class which only has the code which is used by all subclasses; and a "desktop" subclass, which implements the rest. Then WinCE/Symbian would only subclass the "base" SDL class.

Windows

  • Add scripting code for creating a Windows installer to our code repository, so that a full Windows release can be built easily and directly. Could be based on NSIS or WiX.

Tools

General

  • Use doxygen (or something else) to turn the short descs from the README into short man pages AND a single text file (replacing README) and a HTML file...

GUI

  • One of the GUI assistants pages shows the following text to the user: "Note: Some tools display file picker here, this should perhaps be changed to always be directory output, since often don't want to name the output file." Clearly this should *not* be shown to the user, but rather is something we devs need to address.
  • The last page of the assistant is weird. E.g. after successful run, it shows a "Finish" button in the lower right, and two checkboxes: "Open output folder" and "Process another file". This seems unintuitive and artificial to me. An IMHO better alternative would be to remove the "Finish" button, and instead show some big buttons with captions like "Process another file" (which does just that), "Open output folder", and "Quit". One can probably still do better, somebody should think about this.

Compression tools

  • (Semi-)automatically provide showhelp function
  • Modify encodeAudio to accept "input streams", so that we can avoid creating temporary WAVE files
  • Improved error checking !!! esp. for FT we got several reports about problems caused by the compression tool being called from the wrong directory. This should be avoidable by implementing suitable checks.

Descumm

  • Turn it into a library, to be used by a command line frontend (like now), ScummVM debugger, and ScummEX. Basically, the API could consist of a single function, which takes a pointer to a memory buffer, its length, the Scumm version and optionally a game id. Also, it would get a pointer to a print function (in the case of the CLI tool, print to stdout; for ScummVM, print to our GUI console; for ScummEX, append to some window/widget)
  • Rewrite code to use 2 passes; first pass builds an intermediate graph, the second pass then tries to detect loops, break/continue statements etc.
  • Proper implementation of o6_startObjectQuick decompilation (see comment in descumm6.c). May require rewrite of core program logic.
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