This document is only relevant for the current ES-DE development version, if you would like to see the documentation for the latest stable release, refer to [INSTALL.md](INSTALL.md) instead.
CMake is the build system for all the supported operating systems, used in conjunction with `make` on Unix and macOS and `jom` on Windows. Xcode on macOS or Visual Studio on Windows are not required for building ES-DE and they have not been used during development.
The Raspberry Pi 4/400 is the minimum recommended version and earlier boards have not been tested. The GPU memory should be set to at least 256 MB using `raspi-config` and the GL driver must be set to `GL (Fake KMS)` or the performance will be horrible.
Note that low-level ALSA sound support has been removed from ES-DE which means that a sound server like PulseAudio or PipeWire is required. Likewise a display server (Xorg or Wayland) is required, direct framebuffer access is not supported.
Only the OpenGL ES 3.0 renderer works on Raspberry Pi and it's enabled by default.
NetBSD ships with GCC by default, and although you should be able to use Clang/LLVM, it's probably easier to just stick to the default compiler environment. The reason why the clang package needs to be installed is to get clang-format onto the system.
The pugixml library does exist in the package collection but somehow this version is not properly detected by CMake, so you need to compile this manually as well:
By default the master branch will be used, which is where development takes place. To instead build a stable release, switch to the `stable-x.x` branch for the version, for example:
Due to buggy AMD GPU drivers it could be a good idea to use the `LSAN_suppressions` file included in the repository to avoid reports of a lot of irrelevant issue, for example:
It could also be a good idea to use the `TSAN_suppressions` file included in the repository to suppress issues reported by some third party libraries, for example:
These tools aren't very useful without debug symbols so only use them for a Debug or Profiling build. Clang and GCC support all three tools. Note that ASAN and TSAN can't be combined.
As for advanced debugging, Valgrind is a very powerful and useful tool which can analyze many aspects of the application. Be aware that some of the Valgrind tools should be run with an optimized build, and some with optimizations turned off. Refer to the Valgrind documentation for more information.
The output file can be loaded into an application such as Massif-Visualizer for analysis.
Another useful tool is `scan-build`, assuming you use Clang/LLVM. This is a static analyzer that runs during compilation to provide a very helpful HTML report of potential bugs (well it should be actual bugs but some false positives could be included). You need to run it for both the cmake and make steps, here's an example:
You open the report with the `scan-view` command which lets you read it using your web browser. Note that the compilation time is much longer when using the static analyzer compared to a normal build. As well this tool generates a lot of extra files and folders in the build tree, so it may make sense to run it in a separate copy of the source folder to avoid having to clean up all this extra data when the analysis has been completed.
An even more advanced static analyzer is `clang-tidy`, to use it first make sure it's installed on your system and then run the following:
```
cmake -DCLANG_TIDY=on .
```
Even though many irrelevant checks are filtered out via the configuration, this will still likely produce a quite huge report (at least until most of the recommendations have been implemented). In the same manner as for scan-view, the compilation time is much longer when using this static analyzer compared to a normal build.
You will most likely need to install additional packages to get this to build. On Debian-based systems these are _libcec-dev_ and _libp8-platform-dev_. Note that the CEC support is currently untested.
By default ES-DE will install under /usr on Linux, /usr/pkg on NetBSD and /usr/local on FreeBSD and OpenBSD although this can be changed by setting the `CMAKE_INSTALL_PREFIX` variable.
The following example will build the application for installtion under /opt:
It's important to understand that this is not only the directory used by the install script, the CMAKE_INSTALL_PREFIX variable also modifies code inside ES-DE used to locate the required program resources. So it's necessary that the install prefix corresponds to the location where the application will actually be installed.
On Linux, if you're not building a package and instead intend to install using `make install` it's recommended to set the installation prefix to /usr/local instead of /usr.
Be aware that if using the GNOME desktop environment, /usr/share/pixmaps/org.es_de.frontend.svg must exist in order for the ES-DE icon to be shown in the Dash and task switcher.
As indicated above, the home directory will always take precedence and any resources or themes located there will override the ones in the installation path, or in the path of the ES-DE executable.
The process to create a Linux AppImage is completely automated. You simply run the AppImage creation script, which has to be executed from the root of the repository:
This script has only been tested on Ubuntu 20.04 LTS and 22.04 LTS. It's generally recommended to go for an older operating system when building the AppImage to achieve compatibility with a larger number of distributions. To build it you need the PipeWire development package installed. The name differs between releases, but for 22.04 LTS it's named _libpipewire-0.3-dev_.
After creating the AppImage it's recommended to delete CMakeCache.txt manually so the BUNDLED_CERTS option is not accidentally enabled when building the other packages.
Both _appimagetool_ and _linuxdeploy_ are required for the build process but they will be downloaded automatically by the script if they don't exist. So to force an update to the latest build tools, delete these two AppImages prior to running the build script.
ES-DE for macOS is built using Clang/LLVM which is the default compiler for this operating system. It's pretty straightforward to build software on this OS. The main problem is that there is no native package manager, but as there are several third party package managers available, this can be partly compensated for. The use of one of them, [Homebrew](https://brew.sh), is detailed below.
Install the Command Line Tools which include Clang/LLVM, Git, make etc. Simply open a terminal and enter the command `clang`. This will open a dialog that will let you download and install the tools.
Following this, install the Homebrew package manager which will simplify the installation of some additional required packages. Run the following in a terminal window:
On macOS all dependencies are built in-tree in the `external` directory tree. There are two scripts in the tools directory that automate this entirely and they are executed such as this:
This can take quite a while as multiple packages are downloaded and compiled. It's important to not have any of the dependency libraries installed using Homebrew as they will interfere with the in-tree build.
Re-running macOS_dependencies_setup.sh will delete and download all dependencies again, and re-running macOS_dependencies_build.sh will clean and rebuild all packages. If you want to recompile a single package, make sure to first set the MACOSX_DEPLOYMENT_TARGET variable:
By default the master branch will be used, which is where development takes place. To instead build a stable release, switch to the `stable-x.x` branch for the version, for example:
Specifically on macOS it seems as if AddressSanitizer generates a lot of false positives regarding container overflows, so it may be necessary to ignore these:
Running ES-DE from the build directory may be a bit flaky as there is no Info.plist file available which is required for setting the proper window mode and such. It's therefore recommended to run the application from the installation directory for any more in-depth testing. But normal debugging can of course be done from the build directory.
A detailed explanation of macOS code signing is beyond the scope of this document, but the CMake option MACOS_CODESIGN_IDENTITY is used to specify the code signing certificate identity, for example:
Assuming the code signing ceritificate is properly setup in Keychain Access, the process will be automatic and the resulting DMG package can be notarized as-is. In order to run cpack from an SSH session you first need to run the following command:
```
security unlock-keychain
```
This is not required if cpack is run from a terminal window started via the desktop interface as the keychain is unlocked as part of the desktop login.
As macOS does not have any package manager which would have handled the library dependencies, we need to bundle the required shared libraries with the application. This is almost completely automated by the build scripts.
As indicated above, the home directory will always take precedence and any resources or themes located there will override the ones in the path of the ES-DE executable.
Only the Microsoft Visual C++ (MSVC) compiler is supported on Windows. Although MinGW/GCC produces higher quality code with ES-DE running around 10% to 25% faster it's unfortunately not sustainable to use it. There are multiple technical issues with third party libraries like severe threading issues with FFmpeg and some libraries like Poppler not being readily available.
If not installing the CMake version supplied by Microsoft, you need to make sure that you have a recent version on your machine or CMake will not be able to detect MSVC correctly.
It's strongly recommended to also install Jom, which is a drop-in replacement for nmake that offers support for building in parallel using multiple CPU cores:\
The way the MSVC environment works is that a specific developer shell is provided where the build environment is properly configured. You open this from the Start menu via `Visual Studio 2022` -> `Visual Studio tools` -> `VC` -> `x64 Native Tools Command Prompt for VS 2022 Current`.
It's important to choose the x64-specific shell and not the x86 variant, as ES-DE will only compile as a 64-bit application.
Alternatively you can temporarily install LLVM, copy clang-format.exe to any directory added to your PATH environment variable and then uninstall LLVM to save a few gigabytes of disk space.
Configure Git. Details about its setup is beyond the scope of this document, but there are many good resources available online. The `Git Bash` shell shipped with Git for Windows is very useful though as it somewhat reproduces a Unix environment using MSYS2.
It's strongly recommended to set line breaks to Unix-style (line feed only) directly in the code editor. But if not done, lines breaks will anyway be converted when running clang-format on the code, as explained [here](INSTALL-DEV.md#using-clang-format-for-automatic-code-formatting).
By default the master branch will be used, which is where development takes place. To instead build a stable release, switch to the `stable-x.x` branch for the version, for example:
On Windows all dependencies are kept in-tree in the `external` directory tree. Most of the libraries can be downloaded in binary form, but a few need to be built from source code. There are two scripts in the tools directory that automate this entirely. You run them like this:
The setup scripts will download and launch an installer for OpenSSL for Windows if this has not already been installed on the build machine. Just run through the installer using the default settings and everything should work fine.
It's assumed that [Jom](https://wiki.qt.io/Jom) is used, but if instead using nmake then just remove _JOM_ from the -G flag argument and remove the -j flag as nmake does not support building in parallel.
There are a number of compiler warnings for the bundled rlottie library. Unfortunately these need to be resolved upstream, but everything should still work fine so the warnings can be ignored for now.
If you are running Windows in a virtualized environment such as QEMU-KVM that does not support HW accelerated OpenGL, you can install the Mesa3D for Windows library, which can be downloaded at [https://fdossena.com/?p=mesa/index.frag](https://fdossena.com/?p=mesa/index.frag).
You simply extract the opengl32.dll file into the ES-DE directory and this will enable the llvmpipe renderer. The performance will be terrible of course, but everything should work and it should be good enough for test building on Windows without having to reboot your computer to a native Windows installation. (Note that you may need to copy opengl32.dll to your RetroArch installation directory as well to get the emulators to work somehow correctly.)
As indicated above, the home directory will always take precedence and any resources or themes located there will override the ones in the path of the ES-DE executable.
There are a couple of Git subtrees in the ES-DE repository for some bundled dependencies. In order to pull updates from these you'll need to add their respective remotes to your local ES-DE repository:
There is a style configuration file named .clang-format located directly at the root of the repository which contains the formatting rules. How to install clang-format is detailed per operating system earlier in this document.
But the recommended approach is to run clang-format from within the editor. If using VSCode, there is an extension available named Clang-Format. After installing this, simply open a source file, right click and choose `Format Document` or use the applicable keyboard shortcut. The first time you do this, you will have to make a choice to perform the formatting using clang-format. The rest should be completely automatic.
Whatever you do, don't set up your editor to run clang-format on commit because if something goes wrong (which has happened in the past) you will potentially commit a lot of garbage which could take some effort to clean up. Adding to this, string literals can get strange formatting from time to time and there are occasionally clang-format bugs that may cause other problems. So always review the formatted code manually before commit.
In some instances you may want to avoid getting code formatted, and you can accomplish this by simply enclosing the lines with the two comments "clang-format off" and "clang-format on", such as this:
Adding a comment on its own line will also prevent some formatting such as turning short functions and lambda expressions into single lines. For this function such a comment has been added:
Of course you would like to get the code formatted according to the clang-format rules in most instances, these workaround are only meant for rare exceptions. Some compromises are necessary when auto-formatting code, at least with clang-format in its current state.
There are some files shipped with ES-DE that need to be pulled from external resources, the first one being the CA certificate bundle to get TLS/SSL support working on Windows.
The CA certificates shipped with ES-DE come directly from the curl project but they're originally supplied by the Mozilla foundation. See [https://wiki.mozilla.org/CA](https://wiki.mozilla.org/CA) for more information about this certificate bundle.
The latest version can be downloaded from [https://curl.se/docs/caextract.html](https://curl.se/docs/caextract.html)
After downloading the file, rename it from `cacert.pem` to `curl-ca-bundle.crt` and move it to the certificates directory i.e.:
ES-DE automatically identifies and excludes MAME BIOS and device files, as well as translating the short MAME ROM names to their full game names. This is done using information from the MAME driver file shipped with the official MAME distribution. The file needs to be converted to an internal format used by ES-DE as the original file is huge and most of the information is not required.
To get hold of the driver file, go to [https://www.mamedev.org/release.php](https://www.mamedev.org/release.php) and select the Windows version, but only download the driver information in XML format and not MAME itself. This file will be named something like `mame0226lx.zip` and unzipping it will give you a filename such as `mame0226.xml`.
You need `xmlstarlet` installed for these scripts to work.
The diff command is used to do a sanity check that the changes look reasonable before deleting the old files. This is an example for the BIOS file when going from driver version 0.221 to 0.226:
```
diff mamebioses.xml mamebioses.xml_OLD
1c1
<<!-- Last updated with information from MAME driver file mame0226.xml -->
---
> <!-- Last updated with information from MAME driver file mame0221.xml -->
51d50
<<bios>kpython</bios>
```
You can also use git for this comparison of course, which may actually provide a clearer visualization of the changes:
The reason to not simply replace the BIOS and devices files with the new version is that we want to retain entries from all older MAME versions as otherwise older ROM sets used on older MAME versions would have missing information. This is so as the MAME project sometimes removes older entries when they're reorganizing the ROM sets. By merging the files we retain backward compatibility but still support the latest MAME version. To clarify, this of course does not affect the emulation itself, but rather the filtering of BIOS and device files inside ES-DE. The mamenames.xml file containing the translation of MAME ROM names to the full game names does not suffer from this problem as it's cumulative, which is why it is simply overwritten.
This file will contain all supported settings at their default values. Normally you shouldn't need to modify this file manually, instead you should be able to use the menu inside ES-DE to update all the necessary settings.
This complete configuration step can normally be skipped as you're presented with a dialog to change the ROM directory upon application startup if no game files are found.
By default, ES-DE looks in `~/ROMs` for the ROM files, where they are expected to be grouped into directories corresponding to the game systems, for example:
There is also support to add the variable %ESPATH% to the ROM directory setting, this will expand to the path where the ES-DE executable is started from. You should normally not need this, but the option is there for special cases. For example:
As ES-DE auto-configures the keyboard and controllers, neither the input configuration step or manual adjustments to the es_input.xml file should normally be needed. Actually, unless the button layout has been customized using the input configurator, the es_input.xml file will not even exist.
But if you have customized your button layout and your controller or keyboard stop working, you can delete the `~/ES-DE/settings/es_input.xml` file to remove the customizations, or you can start ES-DE with the `--force-input-config` command line option to make the input configurator appear.
_The --anti-aliasing option is not available if ES-DE is built using the OpenGL ES renderer and the --no-update-check option is not available for builds where the application updater is disabled._
As you can see above, you can override the home directory path using the `--home` flag. So by running for instance the command `es-de --home ~/games/emulation`, ES-DE will use `~/games/emulation/ES-DE` as its application data directory. Be aware that this option completely replaces what is considered the home directory, meaning the default ROM directory ~/ROMs would be resolved to ~/games/emulation/ROMs. The same is true for the emulator core locations if es_find_rules.xml is configured to look for them relative to the home directory. So of course RetroArch and other emulators would also need to be configured to use ~/games/emulation as its base directory in this instance.
Setting --resolution to a lower or higher value than the display resolution will add a border to the application window. The exception is if defining a lower resolution than the display resolution in combination with the --fullscreen-padding flag as this will pad the screen contents on a black background. This can be combined with the --screenoffset option for exact positioning on displays where bezels or similar may obstruct part of the viewable area.
The --no-update-check option only disabled the application updater for the current startup. To permanently disable this functionality use the _Check for application updates_ option in the _Other settings_ menu. The command line option is primarily intended for the unlikely event that the application updater breaks the application and makes it impossible to start.
Running with the --create-system-dirs option will generate all the game system directories in the ROMs folder. This is equivalent to starting ES-DE with no game ROMs present and pressing the _Create directories_ button. Detailed output for the directory creation will be available in es_log.txt and the application will quit immediately after the directories have been created. By default placeholder entries will be skipped, if you want to still create these directories then set the CreatePlaceholderSystemDirectories option to true in es_settings.xml.
As well, passing the option --ignore-gamelist will disable the ParseGamelistOnly setting controlled by --gamelist-only and immediately save the es_settings.xml file. If passing both the --ignore-gamelist and --gamelist-only parameters then --ignore-gamelist will take precedence and --gamelist-only will be ignored.
The --ignore-gamelist option is only active during the program session and is not saved to es_settings.xml. But --gamelist-only is however saved, so in order to return to the normal operation of parsing the gamelist.xml files after starting ES-DE with the --gamelist-only option, you will need to disable the setting _Only show games from gamelist.xml files_ in the _Other settings_ menu (or manually change the ParseGamelistOnly entry in es_settings.xml).
On all platforms except Android and Windows it's possible to change the application data directory to something else than ~/ES-DE if you prefer that. This is accomplished using the ESDE_APPDATA_DIR environment variable, for example like the following:
There are some settings which are not configurable via the GUI as modifying these should normally not be required. To still change these, edit the es_settings.xml file directly.
If a system in es_systems.xml has a single command tag with the text _PLACEHOLDER_ anywhere in the tag (regardless of letter case) then its directory and _systeminfo.txt_ file will not get created when running with the --create-system-dirs command line option, or when using the _Create/update system directories_ entry in the _Utilities_ menu or when pressing the _Create directories_ button in the no-games startup dialog. However setting this option to true will override the behavior so the placeholder directories will still be created.
Enabling this will skip all debug messages about missing files specifically for custom collections when loading a theme. Note that DebugSkipMissingThemeFiles takes precedence, so if that setting is set to true then the DebugSkipMissingThemeFilesCustomCollections setting will be ignored. Default value is true.
As of ES-DE 2.0.0 any gamelist.xml files stored in the game system directories (e.g. under `~/ROMs/`) will not get loaded, they are instead required to be placed in the `~/ES-DE/gamelists/` directory tree. By setting this option to `true` it's however possible to retain the old behavior of first looking for gamelist.xml files in the system directories on startup. Note that even if this setting is enabled ES-DE will still always create new gamelist.xml files under `~/ES-DE/gamelists/` which was the case also for the 1.x.x releases.
If using the regular desktop OpenGL renderer, the allowed values are 3.3 (default on all builds except the Steam Deck), 4.2 and 4.6 (default on the Steam Deck). If using the OpenGL ES renderer, the allowed values are 3.0 (default), 3.1 and 3.2.
Sets the server connection timeout for the scraper. Minimum value is 0 seconds (infinity) and maximum value is 300 seconds. Default value is 30 seconds.
Normally the scraper will stop whenever an HTTP error code with value 400 or above is returned from the scraper service, but by default there is an exception for 404 errors (resource not found). Changing this setting to _false_ will make the scraper handle 404 errors as all other error codes, meaning it will run through the configured retry attempts and then display an error notification dialog if the resource could not be retrieved.
The file is located in the resources directory in the same location as the es_systems.xml file, but a customized copy can be placed in ~/ES-DE/custom_systems, which will complement the bundled file.
It's pretty straightforward, there are currently four rules supported for finding emulators, `winregistrypath`, `winregistryvalue`, `systempath` and `staticpath` and there is one rule supported for finding the emulator cores, `corepath`.
Of these, `winregistrypath` and `winregistryvalue` are only available on Windows, and attempting to use the rule on any other operating system will generate a warning in the log file when processing the es_find_rules.xml file.
Here %EMULATOR_ and %CORE_ are followed by the string RETROARCH which corresponds to the name attribute in es_find_rules.xml. The name is case sensitive but it's recommended to use uppercase names to make the variables feel consistent (%EMULATOR_retroarch% doesn't look so pretty).
The find rules can also be used by the %PRECOMMAND_ variable, which is for instance useful for running Windows emulators on Linux using Wine or Proton. In the following example two separate find rules are used, one for the %PRECOMMAND_ variable and another one for the %EMULATOR_ variable:
The `winregistrypath` rule searches the Windows Registry "App Paths" keys for the emulators defined in the `<entry>` tags. If for example this tag is set to `retroarch.exe`, a search will be performed for the key `SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\retroarch.exe`. HKEY_CURRENT_USER is tried first, and if no key is found there, HKEY_LOCAL_MACHINE is tried as well. In addition to this, ES-DE will check that the binary defined in the default value for the key actually exists. If not, it will proceed with the next rule. Be aware that the App Paths keys are added by the emulators during their installation, and although RetroArch does add this key, not all emulators do.
The `winregistryvalue` rule will search for the specific registry value, and if it exists, it will use that value as the path to the emulator binary. HKEY_CURRENT_USER will be tried first, followed by HKEY_LOCAL_MACHINE. In the same manner as `winregistrypath`, ES-DE will check that the binary defined in the registry value actually exists. If not, it will proceed with the next rule. For example, if setting the `<entry>` tag for this rule to `SOFTWARE\Valve\Steam\SteamExe`, the emulator binary would be set to `c:\program files (x86)\steam\steam.exe`, assuming that's where Steam has been installed. As this rule can be used to query any value in the Registry, it's a quite powerful tool to locate various emulators and applications. In addition to this it's posssible to append an arbitrary string to the key value if it's found and use that as the emulator binary path. This is accomplished by using the pipe sign, so for example the entry `SOFTWARE\PCSX2\Install_Dir|\pcsx2.exe` will look for the key `SOFTWARE\PCSX2\Install_Dir` and if it's found it will take the value of that key and append the string `\pcsx2.exe` to it. This could for example result in `C:\Program Files (x86)\PCSX2\pcsx2.exe`. Also for this setup, ES-DE will check that the emulator binary actually exists, or it will proceed to the next rule.
The other rules are probably self-explanatory with `systempath` searching the PATH environment variable for the binary names defined by the `<entry>` tags and `staticpath` defines absolute paths to the emulators. For staticpath, the actual emulator binary must be included in the entry tag. Wildcards (*) are supported for the emulator binary, but not for directories. Wildcards are very useful for AppImages which often embed version information into the filenames. Note that if multiple files match a wildcard pattern, the first file returned by the operating system will be selected.
There is also support for substituting the emulator binary in a staticpath rule with an explicit command. To accomplish this add a pipe (|) character after the emulator entry followed by the command to execute. This is for example useful for Flatpaks when you want to check the presence of a package while still launching a specific command inside the package using the --command option. For example:
This will execute the regular logic of checking if the Mednaffe Flatpak is installed but will actually run the command after the pipe character when launching the game. Note that no checks or controls are in place for the explicitly defined command, it's just blindly executed.
The winregistrypath rules are always processed first, followed by winregistryvalue, then systempath and finally staticpath. This is done regardless of which order they are defined in the es_find_rules.xml file.
The %ESPATH% and %ROMPATH% variables can be used inside the staticpath rules and the %ESPATH% and %EMUPATH% variables can be used inside the corepath rules.
The tilde symbol `~` is supported for the staticpath and corepath rules and will expand to the user home directory. Be aware that if ES-DE has been started with the --home command line option, the home directory is considered to be whatever path was passed as an argument to that option. The same is true if using a portable.txt file.
The es_systems.xml file contains the game systems configuration data for ES-DE, written in XML format. This defines the system name, the full system name, the ROM path, the allowed file extensions, the launch command, the platform (for scraping) and the theme to use.
ES-DE ships with a comprehensive `es_systems.xml` file and most users will probably never need to make any customizations. But there may be special circumstances such as wanting to use different emulators for some game systems or perhaps to add additional systems altogether.
To accomplish this, ES-DE supports customizations via a separate es_systems.xml file that is to be placed in the `custom_systems` folder in the application home directory, i.e. `~/ES-DE/custom_systems/es_systems.xml`. (The tilde symbol `~` translates to `$HOME` on Unix and macOS, and to `%HOMEPATH%` on Windows unless overridden via the --home command line option.)
This custom file functionality is designed to be complementary to the bundled es_systems.xml file, meaning you should only add entries to the custom configuration file for game systems that you actually want to add or override. So to for example customize a single system, this file should only contain a single `<system>` tag. The structure of the custom file is identical to the bundled file with the exception of an additional optional tag named `<loadExclusive/>`. If this is placed in the custom es_systems.xml file, ES-DE will not load the bundled file. This is normally not recommended and should only be used for special situations. At the end of this section you can find an example of a custom es_systems.xml file.
The bundled es_systems.xml file is located in the resources directory that is part of the application installation. For example this could be `/usr/share/es-de/resources/systems/linux/es_systems.xml` on Linux, `/Applications/ES-DE.app/Contents/Resources/resources/systems/macos/es_systems.xml` on macOS or `C:\Program Files\ES-DE\resources\systems\windows\es_systems.xml` on Windows. The actual location may differ from these examples of course, depending on where ES-DE has been installed.
If you're using the AppImage release of ES-DE then the bundled es_systems.xml file is embedded in the AppImage together with the rest of the resources.
It doesn't matter in which order you define the systems as they will be sorted by the `<fullname>` tag or by the optional `<systemsortname>` tag when displayed inside the application. But it's still a good idea to add the systems in alphabetical order to make the configuration file easier to maintain.
Note that the `<systemsortname>` tags are sorted in [lexicographic order](https://en.wikipedia.org/wiki/Lexicographic_order) so 11 will be sorted above 2 but 002 will be sorted above 011.
But instead of changing the sorting directly in the es_systems.xml file it could be a better idea to use the dedicated es_systems_sorting.xml file instead. How to do that is described later in this document.
Wildcards are supported for emulator binaries, but not for directories:
```xml
<!-- This is supported, first matching file will be selected -->
There is a special case when it comes to file extensions where it's possible to use extensionless files if required. To accomplish this simply add a dot (.) to the list of extensions in the `<extension>` tag. Obviously this makes it impossible to use the _directories interpreted as files_ functionality as there is no file extension, but apart from that everything should work the same as for regular files.
Keep in mind that you have to set up your emulators separately from ES-DE as the es_systems.xml file assumes that your emulator environment is properly configured.
Below is an overview of the file layout with various examples. For the command tag, the newer es_find_rules.xml logic described later in this document removes the need for most of the legacy options, but they are still supported for special configurations and for backward compatibility with old configuration files.
```xml
<?xml version="1.0"?>
<!-- This is the ES-DE game systems configuration file. -->
<systemList>
<!-- Any tag not explicitly described as optional in the description is mandatory.
If omitting a mandatory tag, ES-DE will skip the system entry during startup. -->
<system>
<!-- A short name. Although there can be multiple identical <name> tags in the file, upon successful loading of a system,
any succeeding entries with identical <name> tags will be skipped. Multiple identical name tags is only required for very
special situations so it's normally recommended to keep this tag unique. -->
<name>snes</name>
<!-- The full system name, used for sorting the systems, for selecting the systems to multi-scrape etc. -->
`%ROMRAW%` - Replaced with the unescaped, absolute path to the selected ROM. If your emulator is picky about paths, you might want to use this instead of %ROM%, but enclosed in quotes.
`%ROMPATH%` - Replaced with the path defined in the setting ROMDirectory in es_settings.xml. If combined with a path that contains blankspaces, then it must be surrounded by quotation marks, for example `%ROMPATH%"\Arcade Games"`. Note that the quotation mark must be located before the directory separator in this case.
`%STARTDIR%` - The directory to start in when launching the emulator. Must be defined as a pair separated by an equal sign. This is normally not required, but some emulators and game engines like standalone MAME and OpenBOR will not work properly unless you're in the correct directory when launching a game. Either an absolute path can be used, such as `%STARTDIR%=C:\Games\mame` or some variables are available that provide various functions. The `%EMUDIR%` variable can be used to start in the directory where the emulator binary is located, i.e. `%STARTDIR%=%EMUDIR%`, the `%GAMEDIR%` variable can be used to start in the directory where the game file is located, i.e. `%STARTDIR%=%GAMEDIR%` and the `%GAMEENTRYDIR%` variable can be used which works identically to `%GAMEDIR%` with the exception that it will interpret the actual game entry as the start directory. This is useful in very rare situations like for the EasyRPG Player where the game directories are interpreted as files but where the game engine must still be started from inside the game directory. If an absolute path is set that contains blankspaces, then it must be surrounded by quotation marks, for example `%STARTDIR%="C:\Retro games\mame"`. If the directory defined by this variable does not exist, it will be created on game launch. The variable can be placed anywhere in the launch command if the %EMULATOR_ variable is used, otherwise it has to be placed after the emulator binary.
`%INJECT%` - This allows the injection of launch arguments or environment variables stored in a text file on the filesystem. The %INJECT% variable must be defined as a pair separated by an equal sign, for example `%INJECT%=game.commands`. The `%BASENAME%` variable can also be used in conjunction with this variable, such as `%INJECT%=%BASENAME%.commands`. By default a path relative to the game file will be assumed but it's also possible to use an absolute path or the ~ (tilde) symbol which will expand to the home directory. If a path contains spaces it needs to be surrounded by quotation marks, such as `%INJECT%="C:\My games\ROMs\daphne\%BASENAME%.daphne\%BASENAME%.commands"`. The variable can be placed anywhere in the launch command and the file contents will be injected at that position. It's also possible to have multiple injections by defining the variable more than once at different locations in the launch command string. The specified file is optional, if it does not exist, is empty, or if there are insufficient permissions to read the file, then it will simply be skipped. For safety reasons the injection file can only have a maximum size of 4096 bytes and if it's larger than this it will be skipped and a warning will be written to es_log.txt.
`%EMUPATH%` - Replaced with the path to the emulator binary. This variable is used for manually specifying emulator core locations, and a check for the existence of the core file will be done on game launch and an error displayed if it can't be found. Normally %EMUPATH% should not be used as the %CORE_ variable is the recommended method for defining core locations.
`%EMUDIR%` - Replaced with the path to the emulator binary. This is a general purpose variable as opposed to %EMUPATH% which is intended specifically for core locations.
`%EMULATOR_` - This utilizes the emulator find rules as defined in `es_find_rules.xml`. This is the recommended way to configure the launch command. The find rules are explained in more detail below.
`%PRECOMMAND_` - This utilizes the emulator find rules as defined in `es_find_rules.xml` to locate a pre-command binary. It's for instance useful for running Windows emulators on Linux using Wine or Proton. The %PRECOMMAND_ entry can be located anywhere in the launch command but it should be placed before the %EMULATOR_ variable in order to work as intended.
`%RUNINBACKGROUND%` - When this variable is present, ES-DE will continue to run in the background while a game is launched. This will also prevent the gamelist video from playing, the screensaver from starting, and the game name and game description from scrolling. This functionality is required for some systems such as Valve Steam. The variable can be placed anywhere in the launch command.
`%HIDEWINDOW%` - This variable is only available on Windows and is used primarily for hiding console windows when launching scripts (used for example by Steam games and source ports). If not defining this, the console window will be visible when launching games. The variable can be placed anywhere in the launch command.
`%ESCAPESPECIALS%` - This variable is only available on Windows and is used to escape the characters &()^=;, for the %ROM% variable, which would otherwise make binaries like cmd.exe fail when launching scripts or links. The variable can be placed anywhere in the launch command.
`%ENABLESHORTCUTS%` - This variable is only available on Unix and macOS and is used to enable shortcuts to games and applications. On Unix these come in the form of .desktop files and ES-DE has a simple parser which essentially extracts the command defined in the Exec key and then executes it. Although some basic file structure checks are performed, the actual command listed with the Exec key is blindly executed. In addition to this the variables %F, %f, %U and %u are removed from the Exec key entry. On macOS shortcuts in the form of .app directories and alias files are executed using the `open -W -a` command. This makes it possible to launch shortcuts to emulators and applications like Steam as well as aliases for any application. However the latter need to be renamed to the .app file extension or it won't work. When a file is matching the .desktop or .app extension respectively, the emulator command defined using the %EMULATOR% variable will be stripped. An %EMULATOR% entry is however still required for the %ENABLESHORTCUTS% variable to work as the intention is to combine shortcuts with the ability to launch shell scripts without having to setup alternative emulators. The %ROM% variable is expanded to the command to execute when using %ENABLESHORTCUTS%, which also means that this variable has to be used, and for example %ROMRAW% will not work.
As well, here's an example for Linux of a custom es_systems.xml file placed in ~/ES-DE/custom_systems/ that overrides a single game system from the bundled configuration file:
<fullname>Nintendo Entertainment System</fullname>
<path>%ROMPATH%/nes</path>
<extension>.nes .NES .zip .ZIP</extension>
<command>/usr/games/fceux %ROM%</command>
<platform>nes</platform>
<theme>nes</theme>
</system>
</systemList>
```
If adding the `<loadExclusive/>` tag to the file, the bundled es_systems.xml file will not be processed. For this example it wouldn't be a very good idea as NES would then be the only platform that could be used in ES-DE.
```xml
<?xml version="1.0"?>
<!-- This is a custom ES-DE game systems configuration file for Unix -->
<loadExclusive/>
<systemList>
<system>
<name>nes</name>
<fullname>Nintendo Entertainment System</fullname>
Here is yet another example with the addition of the `snes` system where some file extensions and alternative emulator entries have been removed, and the full name and sorting have been modified.
```xml
<?xml version="1.0"?>
<!-- This is a custom ES-DE game systems configuration file for Unix -->
<systemList>
<system>
<name>nes</name>
<fullname>Nintendo Entertainment System</fullname>
ES-DE works a bit differently on Android which is also reflected in the es_find_rules.xml and es_systems.xml configuration. Emulators on Android are launched via so-called _Intents_ which is an API rather than the typical command line approach used on Unix systems. Although ES-DE on Windows also uses an API call to launch emulators it's still closely connected to the regular operating system paradigms on how to start binaries and pass application options so the systems configuration still looks quite traditional. On Android this is not the case and there is therefore a heavy use of variables to reflect the Intent API functionality.
There is a command line tool in Android named _am_ which implements the _Intent_ API and can be used to test emulator launching, but this is not intended to be used by other applications and therefore ES-DE implements direct (albeit partial) support for the Intent API. Testing the modern FileProvider interface using the _am_ utility is unfortunately not really possible as access permission is provided by the calling process, i.e. ES-DE.
The es_find_rules.xml and es_systems.xml files are kept in an Android-internal directory and can't be accessed directly, but you can find them at the following location:\
The es_find_rules.xml file is structured the same as for the other operating systems but there'a special _androidpackage_ find rule where you define the name of the emulator package as well as optionally which _activity_ to launch. If the activity is not defined then the default one for the package will be used. Although this may work in some instances it's usually a good idea to explicity set it. Apart from that the find rules work as on the other platforms, i.e. they will be traversed in the order they are defined. So by adding multiple _androidpackage_ entries for an emulator it's possible to look for multiple releases or forks without having to create separate emulator entries in es_systems.xml. It's also possible to override find rules by adding an ES-DE/custom_systems/es_find_rules.xml file, again the same logic applies as for all other platforms.
The _androidpackage_ find rule entries are structured as `<entry>packagename/activity</entry>` and if only a package is defined then the forward slash can be omitted, i.e. only `<entry>packagename</entry>` is needed.
The es_systems.xml file on Android utilizes variables heavily to implement the _Intent_ API and these variables are covered in detail below. It's possible to override the systems configuration by adding an ES-DE/custom_systems/es_systems.xml file, the same logic applies as for all other platforms.
`%EMULATOR_` - This utilizes the emulator find rules as defined in `es_find_rules.xml`. This is the only way to configure the launch command on Android and it works identically to the other platforms.
`%MIMETYPE%` - Sets an explicit MIME type, which you need to assign using an equal sign such as %MIMETYPE%=text/plain. You will rarely, if ever, need to set an explicit MIME type so this variable is of limited use. By default Android will set the MIME type to application/octet-stream which is normally what you want.
There are two main ways to pass options to emulators, using _extras_ or using the _data_ URI. There can only be a single data URI but there can be an arbitrary amount of extras. To understand more about the way this works, you can read about the _putExtra()_ and and _setData()_ functions here:\
`%EXTRA_` - This passes an _extra_ which contains any additional information that the emulator may support. This is provided as a key/value pair where you define the key name following the literal %EXTRA_ string and terminate it with a % sign and then assign the value using an equal sign. For example %EXTRA_LIBRETRO%=puae_libretro_android.so will pass the extra named _LIBRETRO_ with its value set to _puae_libretro_android.so_. You can pass an unlimited number of extras and you can also use various ROM variables in combination with this as described below.
`%EXTRAARRAY_` - Defines an array of comma-separated string values following the key name. Only literal strings are supported, so this can't be used in combination with any ROM variables. As commas are used as separator characters, you'll need to escape any comma signs that you want to include in the actual value. For example %EXTRAARRAY_Parameters%=pone,p\\,two,pthree will pass the extra named _Parameters_ with the three separate array entries _pone_, _p,two_ and _pthree_.
`%EXTRABOOL_` - Sets an extra with a boolean value, i.e. true/1 or false/0.
`%DATA%` - Sets the data URI value for the intent using an equal sign. This is normally combined with one of the ROM variables.
`%ROM%` - Replaced with the absolute path to the selected ROM. This is a traditional method to provide the game ROM and its use will likely decrease or go away completely long term as emulators move to more modern methods.
`%ROMSAF%` - Replaced with an Android Storage Access Framework (SAF) document URI which always starts with the _content://com.android.externalstorage.documents/_ string. You can read more about the SAF here:\
`%ROMPROVIDER%` - This is the most modern approach to passing game ROMs to emulators. It uses the _FileProvider_ API to provide permissions to the file. This means that you don't need to setup the emulator upfront to have access to the directory where the game file is stored, access is instead temporarily granted by ES-DE. You can read more about the FileProvider API here:\
The `%ROM%` and `%ROMSAF%` variables can be used with both the `%DATA%` and `%EXTRA_` variables, but `%ROMPROVIDER%` can only be used with the `%DATA%` variable. For the `%DATA%` variable you'll just assign the ROM variable with an equal sign as there can only be a single _setData()_ API call per Intent. For the `%EXTRA_` variable you need to specify a name of the extra and then define it using an equal sign as an arbitrary amount of _putExtra()_ API calls can be used for an Intent.
`%ACTIVITY_CLEAR_TASK%` - If set in an Intent passed to Context.startActivity(), this flag will cause any existing task that would be associated with the activity to be cleared before the activity is started. That is, the activity becomes the new root of an otherwise empty task, and any old activities are finished.
`%ACTIVITY_CLEAR_TOP%` - If set, and the activity being launched is already running in the current task, then instead of launching a new instance of that activity, all of the other activities on top of it will be closed and this Intent will be delivered to the (now on top) old activity as a new Intent.
`%ACTIVITY_NO_HISTORY%` - If set, the new activity is not kept in the history stack. As soon as the user navigates away from it, the activity is finished. This may also be set with the noHistory attribute. If set, onActivityResult() is never invoked when the current activity starts a new activity which sets a result and finishes.
This file makes it possible to apply custom systems sorting without having to modify the es_systems.xml file directly. It should be placed in the custom_systems directory, e.g. `~/ES-DE/custom_systems/es_systems_sorting.xml`
The structure of this file is essentially a simplified version of the es_systems.xml file, but with only the `<name>` and `<systemsortname>` tags present per system.
You only need to include systems that you want to customize sorting for, and if there's also a systemsortname tag present in the es_systems.xml file for any system, then the es_systems_sorting.xml entry will take precedence.
Note that the `<systemsortname>` tags are sorted in [lexicographic order](https://en.wikipedia.org/wiki/Lexicographic_order) so 11 will be sorted above 2 but 002 will be sorted above 011. Secondary sorting will always be done by the fullname tag in es_systems.xml.
There are also four complete sorting files bundled with ES-DE, you can find them in the resources/sorting/ directory, or you can access them [here](https://gitlab.com/es-de/emulationstation-de/-/tree/master/resources/sorting).
These files include all systems supported by ES-DE and provide the following sorting options:
* Release year
* Manufacturer, release year
* Hardware type, release year
* Manufacturer, hardware type, release year
You can apply any of these sorting files via the _Systems sorting_ option in the _Other settings_ menu. Note that in order to load a es_systems_sorting.xml file placed in the custom_systems directory you'll need to set this option to _Full names or custom_.
As of the fork to ES-DE, game media information no longer needs to be defined in the gamelist.xml files. Instead the application will look for any media matching the ROM filename. The media path where to look for game media is configurable either manually in `es_settings.xml` or via the GUI. If configured manually in es_settings.xml, it looks something like this:
There is also support to add the variable %ESPATH% to the media directory setting, this will expand to the path where the ES-DE executable is started from. You should normally not need this, but the option is there for special cases. For example:
You can use ES-DE's scrapers to populate the gamelist.xml files, or manually update individual entries using the metadata editor. All of this is explained in the [User guide](USERGUIDE-DEV.md).
An example gamelist.xml entry for the Commodore 64 game Popeye:
```xml
<?xml version="1.0"?>
<gameList>
<game>
<path>./cartridge/Popeye/Popeye.crt</path>
<name>Popeye</name>
<desc>Popeye is a conversion of the arcade action/platform game.</desc>
<rating>0.7</rating>
<releasedate>19860101T000000</releasedate>
<developer>Parker Brothers</developer>
<publisher>Nintendo</publisher>
<genre>Action</genre>
<players>1-2</players>
<favorite>true</favorite>
</game>
</gameList>
```
Everything is enclosed in a `<gameList>` tag, and the information for each game or folder is enclosed in a corresponding `<game>` or `<folder>` tag. Each piece of metadata is encoded as a string.
Some metadata is also marked as "statistic", these are kept track of by ES-DE and do not show up in the metadata editor. They are shown in certain views (for example, the detailed view and the video view both show `lastplayed`, although the label can be disabled by the theme).
*`desc` - string, a description of the game, longer descriptions will automatically scroll, so don't worry about the size
*`rating` - float, the rating for the game, expressed as a floating point number between 0 and 1. Fractional values will be rounded to 0.1 increments (half-stars) during processing
*`releasedate` - datetime, the date the game was released, displayed as date only, time is ignored
*`developer` - string, the developer for the game
*`publisher` - string, the publisher for the game
*`genre` - string, the genre(s) for the game
*`players` - integer, the number of players the game supports
*`favorite` - bool, indicates whether the game is a favorite
*`completed` - bool, indicates whether the game has been completed
*`kidgame` - bool, indicates whether the game is suitable for children, as used by the `Kid' UI mode
*`hidden` - bool, indicates whether the game is hidden
*`broken` - bool, indicates a game that doesn't work (useful for MAME)
*`nogamecount` - bool, indicates whether the game should be excluded from the game counter and the automatic and custom collections
*`nomultiscrape` - bool, indicates whether the game should be excluded from the multi-scraper
*`hidemetadata` - bool, indicates whether to hide most of the metadata fields when displaying the game in the gamelist view
*`playcount` - integer, the number of times this game has been played
*`lastplayed` - statistic, datetime, the last date and time this game was played
For folders, most of the fields are identical although some are removed. In the list below, the fields with identical function compared to the game files described above have been left without a description.
* If a value matches the default for a particular piece of metadata, ES-DE will not write it to the gamelist.xml file (for example, if `genre` isn't specified, an empty genre tag will not be written)
* A `game` can actually point to a folder/directory if the folder has a matching extension, although this is exceedingly rare
* The `folder` metadata will only be used if a game file is found inside that folder, as empty folders will be skipped during startup even if they have metadata values defined for themselves
* ES-DE will keep entries for games and folders that it can't find the game/ROM files for, i.e. it will not clean up the gamelist.xml files automatically when game files are missing
* The switch `--gamelist-only` can be used to skip automatic searching, and only display games defined in the gamelist.xml files
* The switch `--ignore-gamelist` can be used to ignore the gamelist upon start of the application (mostly useful for debugging purposes)
By enabling the _Debug mode_ setting in the _Other settings_ menu or by passing the --debug command line option, ES-DE will increase the logging to include a lot of additional debug output which is useful both for development and in order to pinpoint issues as a user.
In addition to this extra logging, a few key combinations are enabled when in debug mode. These are useful both for working on ES-DE itself as well as for theme developers.
This option only applies to menus, where it will render a grid on the user interace. Note that any open screen needs to be closed and reopened again after using the key combination in order for it to have any effect.
This will reload either a single gamelist or all gamelists depending on where you're located when entering the key combination (go to the system view to make a complete reload). Very useful for theme development as any changes to the theme files will be activated without requiring an application restart. Note that the menu needs to be closed for this key combination to have any effect.
By default all controller input (keyboard and controller button presses) will be logged when in debug mode. To disable the input logging, the setting DebugSkipInputLogging kan be set to false in the es_settings.xml file. There is no menu entry to change this as it's intended for developers and not for end users.
Before attempting to add a custom profile for your controller you need to check whether there is device driver support for it in your operating system. If the controller works in other applications and games, then proceed with the instructions below, but if it doesn't work anywhere else then chances are very low that you can get it to work in ES-DE.
ES-DE uses the [SDL](https://www.libsdl.org) (Simple DirectMedia Layer) library to handle controller input, so in order for a controller to work in ES-DE, it has to be supported by SDL. There is however a possibility to add custom controller profiles to SDL which in some cases could enable devices in ES-DE that would otherwise not be supported. This is generally a temporary solution though, as controller support is constantly getting improved natively in SDL. As a first step it's therefore recommended to open a request at the SDL [issue tracker](https://github.com/libsdl-org/SDL/issues) to have your specific controller added to a future SDL release.
Assuming the controller works in other applications than ES-DE, you can attempt to add a custom profile by creating the file `~/ES-DE/controllers/es_controller_mappings.cfg` and enter the appropriate configuration inside this file.
But just do this as a first step to see whether you controller gets enabled. If it does, then you should remove all entries that are not relevant. That is important as this file will take precedence over the built-in controller profiles in the SDL library, so any future controller bug fixes and similar would not apply. In the past the gamecontrollerdb.txt file has also included some invalid configuration entries, so even though it may make your controller work, it could actually break some other controllers that you may want to use now or in the future.
Therefore only keep the entries in the es_controller_mappings.cfg file that are relevant for your devices. You can find each relevant controller GUID by starting ES-DE and then looking in the `~/ES-DE/logs/es_log.txt` file. You should see entries such as the following:
May 16 18:26:17 Info: Added controller with custom configuration: "X360 Controller" (GUID: 030000005e0400008e02000010010000, instance ID: 0, device index: 0)
```
It's the GUID that is the key, and it's the lines matching these IDs that you want to retain inside the es_controller_mappings.cfg file. All other rows can be deleted.
Even if pasting the entire content of gamecontrollerdb.txt into the es_controller_mappings.cfg file did not enable your controller, all hope is not lost. You may still be able to create your own custom controller entry, but doing that is beyond the scope of this document and you would have to look into the instructions at the SDL_GameControllerDB URL mentioned above.
As a final note, this configuration file can also be used for the opposite purpose, i.e. to blacklist devices so that they will not work inside ES-DE. Some wireless controllers with buggy drivers will register as two devices meaning every button press will be registered twice. In this situation, blacklisting one of these entries will make the controller behave correctly. Although it's possible to enable the _Only accept input from first controller_ menu option as a workaround, this will completely ignore all other controllers which may not be what you want. To blacklist a controller, follow the same procedure described above but leave the button configuration blank for the GUID entry.
_As there is a preconfigured portable release available for Windows, this section is mostly relevant for understanding how the setup works, as well as to provide information on how to make customizations._
This is just an example as you may of course not use these specific emulators. There are also many more emulators supported as detailed in the `es_find_rules.xml` configuration file. As well there will be many more files and directories than those listed above inside the F:\ES-DE folder.
How the portable setup works is that when ES-DE finds a file named portable.txt in its executable directory, it will by default locate the ES-DE application data directory directly inside this folder. It's also possible to modify portable.txt with a path relative to the ES-DE executable directory. For instance if two dots `..` are placed inside the portable.txt file, then the ES-DE application data directory will be located in the parent folder, which would be directly under F:\ for this example.
Start ES-DE from the F:\ device and check that everything works as expected. Just be aware that some emulators may not play that well with a portable setup and may store their configuration files in your home directory (probably on your C: drive) or at some other location. So when using the portable installation on another computer you may need to perform some additional emulator-specific setup.
You could alternatively copy over your entire ES-DE application data directory, but in this case make sure that you have no settings in es_settings.xml that point to a specific location on your local filesystem, such as the game ROMs or game media directories.
Just make sure to not place the portable installation on a network share that uses the Microsoft SMB protocol and run it from there as this will lead to unacceptably poor application performance.
There are numerous locations throughout ES-DE where custom scripts can be executed if the option to do so has been enabled in the settings. You'll find the option _Enable custom event scripts_ on the Main menu under _Other settings_. By default this setting is deactivated so make sure to enable it to use this feature.
The approach is quite straightforward, ES-DE will look for any files inside a script directory that corresponds to the event that is triggered and will then attempt to execute all these files (regardless of their file extensions). If you want to have the scripts executed in a certain order you can name them accordingly as they will be sorted and executed in lexicographic order. The sorting is case-sensitive on Unix/Linux and case-insensitive on macOS and Windows. ES-DE will wait for each script to finish its execution before moving on to the next one, so the application will suspend briefly when whatever the script is doing is executing. If you want to avoid this you can setup a wrapper script that executes another script outside the ES-DE scripts directory as a background process. Refer to your operating system documentation on how to accomplish this.
On Windows it's also possible to place .lnk shortcut files in the event directories to have these executed in the same manner as a script. Note that while PowerShell scripts can't be executed directly they can be run via either a .lnk shortcut file or a .bat wrapper script where you explicitly call powershell.exe with the -command flag. Just be aware that by default the execution of PowerShell scripts is disabled on Windows. Further details about PowerShell is beyond the scope of this document.
The following examples are for Unix systems, but it works the same way on macOS and Windows (although .bat batch files are used on Windows instead of shell scripts and any spaces in the parameters are not escaped as is the case on Unix and macOS).
After creating the directories, we need to create the scripts to log the actual game launch and game ending. The parameters that are passed to the scripts vary depending on the type of event, but for these events the four parameters are the absolute path to the game file, the game name as shown in the gamelist view, the system name and the full system name.
Aug 05 14:19:24 Debug: Scripting::fireEvent(): game-start "/home/myusername/ROMs/nes/Legend\ of\ Zelda,\ The.zip" "The Legend Of Zelda" "nes" "Nintendo Entertainment System"
Aug 05 14:19:24 Debug: Executing: /home/myusername/ES-DE/scripts/game-start/game_start_logging.sh "/home/myusername/ROMs/nes/Legend\ of\ Zelda,\ The.zip" "The Legend Of Zelda" "nes" "Nintendo Entertainment System"
Aug 05 14:27:15 Debug: Scripting::fireEvent(): game-end "/home/myusername/ROMs/nes/Legend\ of\ Zelda,\ The.zip" "The Legend Of Zelda" "nes" "Nintendo Entertainment System" ""
Aug 05 14:27:15 Debug: Executing: /home/myusername/ES-DE/scripts/game-end/game_end_logging.sh "/home/myusername/ROMs/nes/Legend\ of\ Zelda,\ The.zip" "The Legend Of Zelda" "nes" "Nintendo Entertainment System"
The last two lines are optional, they're used to set the focus back to ES-DE in case you're running attention-seeking applications such as Kodi which may steal focus after resolution changes. You may need to adjust the sleep time to get this to work reliably though, as the timing may differ between different computers and graphics drivers.
After creating the two scripts, you should have something like this on the filesystem:
