SDL/include/SDL3/SDL_init.h

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2026 Sam Lantinga <[email protected]>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/

/**
 * # CategoryInit
 *
 * All SDL programs need to initialize the library before starting to work
 * with it.
 *
 * Almost everything can simply call SDL_Init() near startup, with a handful
 * of flags to specify subsystems to touch. These are here to make sure SDL
 * does not even attempt to touch low-level pieces of the operating system
 * that you don't intend to use. For example, you might be using SDL for video
 * and input but chose an external library for audio, and in this case you
 * would just need to leave off the `SDL_INIT_AUDIO` flag to make sure that
 * external library has complete control.
 *
 * Most apps, when terminating, should call SDL_Quit(). This will clean up
 * (nearly) everything that SDL might have allocated, and crucially, it'll
 * make sure that the display's resolution is back to what the user expects if
 * you had previously changed it for your game.
 *
 * SDL3 apps are strongly encouraged to call SDL_SetAppMetadata() at startup
 * to fill in details about the program. This is completely optional, but it
 * helps in small ways (we can provide an About dialog box for the macOS menu,
 * we can name the app in the system's audio mixer, etc). Those that want to
 * provide a _lot_ of information should look at the more-detailed
 * SDL_SetAppMetadataProperty().
 */

#ifndef SDL_init_h_
#define SDL_init_h_

#include <SDL3/SDL_stdinc.h>
#include <SDL3/SDL_error.h>
#include <SDL3/SDL_events.h>

#include <SDL3/SDL_begin_code.h>
/* Set up for C function definitions, even when using C++ */
#ifdef __cplusplus
extern "C" {
#endif

/* As of version 0.5, SDL is loaded dynamically into the application */

/**
 * Initialization flags for SDL_Init and/or SDL_InitSubSystem
 *
 * These are the flags which may be passed to SDL_Init(). You should specify
 * the subsystems which you will be using in your application.
 *
 * \since This datatype is available since SDL 3.2.0.
 *
 * \sa SDL_Init
 * \sa SDL_Quit
 * \sa SDL_InitSubSystem
 * \sa SDL_QuitSubSystem
 * \sa SDL_WasInit
 */
typedef Uint32 SDL_InitFlags;

#define SDL_INIT_AUDIO      0x00000010u /**< `SDL_INIT_AUDIO` implies `SDL_INIT_EVENTS` */
#define SDL_INIT_VIDEO      0x00000020u /**< `SDL_INIT_VIDEO` implies `SDL_INIT_EVENTS`, should be initialized on the main thread */
#define SDL_INIT_JOYSTICK   0x00000200u /**< `SDL_INIT_JOYSTICK` implies `SDL_INIT_EVENTS` */
#define SDL_INIT_HAPTIC     0x00001000u
#define SDL_INIT_GAMEPAD    0x00002000u /**< `SDL_INIT_GAMEPAD` implies `SDL_INIT_JOYSTICK` */
#define SDL_INIT_EVENTS     0x00004000u
#define SDL_INIT_SENSOR     0x00008000u /**< `SDL_INIT_SENSOR` implies `SDL_INIT_EVENTS` */
#define SDL_INIT_CAMERA     0x00010000u /**< `SDL_INIT_CAMERA` implies `SDL_INIT_EVENTS` */

/**
 * Return values for optional main callbacks.
 *
 * Returning SDL_APP_SUCCESS or SDL_APP_FAILURE from SDL_AppInit,
 * SDL_AppEvent, or SDL_AppIterate will terminate the program and report
 * success/failure to the operating system. What that means is
 * platform-dependent. On Unix, for example, on success, the process error
 * code will be zero, and on failure it will be 1. This interface doesn't
 * allow you to return specific exit codes, just whether there was an error
 * generally or not.
 *
 * Returning SDL_APP_CONTINUE from these functions will let the app continue
 * to run.
 *
 * See
 * [Main callbacks in SDL3](https://wiki.libsdl.org/SDL3/README-main-functions#main-callbacks-in-sdl3)
 * for complete details.
 *
 * \since This enum is available since SDL 3.2.0.
 */
typedef enum SDL_AppResult
{
    SDL_APP_CONTINUE,   /**< Value that requests that the app continue from the main callbacks. */
    SDL_APP_SUCCESS,    /**< Value that requests termination with success from the main callbacks. */
    SDL_APP_FAILURE     /**< Value that requests termination with error from the main callbacks. */
} SDL_AppResult;

/**
 * Function pointer typedef for SDL_AppInit.
 *
 * These are used by SDL_EnterAppMainCallbacks. This mechanism operates behind
 * the scenes for apps using the optional main callbacks. Apps that want to
 * use this should just implement SDL_AppInit directly.
 *
 * \param appstate a place where the app can optionally store a pointer for
 *                 future use.
 * \param argc the standard ANSI C main's argc; number of elements in `argv`.
 * \param argv the standard ANSI C main's argv; array of command line
 *             arguments.
 * \returns SDL_APP_FAILURE to terminate with an error, SDL_APP_SUCCESS to
 *          terminate with success, SDL_APP_CONTINUE to continue.
 *
 * \since This datatype is available since SDL 3.2.0.
 */
typedef SDL_AppResult (SDLCALL *SDL_AppInit_func)(void **appstate, int argc, char *argv[]);

/**
 * Function pointer typedef for SDL_AppIterate.
 *
 * These are used by SDL_EnterAppMainCallbacks. This mechanism operates behind
 * the scenes for apps using the optional main callbacks. Apps that want to
 * use this should just implement SDL_AppIterate directly.
 *
 * \param appstate an optional pointer, provided by the app in SDL_AppInit.
 * \returns SDL_APP_FAILURE to terminate with an error, SDL_APP_SUCCESS to
 *          terminate with success, SDL_APP_CONTINUE to continue.
 *
 * \since This datatype is available since SDL 3.2.0.
 */
typedef SDL_AppResult (SDLCALL *SDL_AppIterate_func)(void *appstate);

/**
 * Function pointer typedef for SDL_AppEvent.
 *
 * These are used by SDL_EnterAppMainCallbacks. This mechanism operates behind
 * the scenes for apps using the optional main callbacks. Apps that want to
 * use this should just implement SDL_AppEvent directly.
 *
 * \param appstate an optional pointer, provided by the app in SDL_AppInit.
 * \param event the new event for the app to examine.
 * \returns SDL_APP_FAILURE to terminate with an error, SDL_APP_SUCCESS to
 *          terminate with success, SDL_APP_CONTINUE to continue.
 *
 * \since This datatype is available since SDL 3.2.0.
 */
typedef SDL_AppResult (SDLCALL *SDL_AppEvent_func)(void *appstate, SDL_Event *event);

/**
 * Function pointer typedef for SDL_AppQuit.
 *
 * These are used by SDL_EnterAppMainCallbacks. This mechanism operates behind
 * the scenes for apps using the optional main callbacks. Apps that want to
 * use this should just implement SDL_AppEvent directly.
 *
 * \param appstate an optional pointer, provided by the app in SDL_AppInit.
 * \param result the result code that terminated the app (success or failure).
 *
 * \since This datatype is available since SDL 3.2.0.
 */
typedef void (SDLCALL *SDL_AppQuit_func)(void *appstate, SDL_AppResult result);


/**
 * Initialize the SDL library.
 *
 * SDL_Init() simply forwards to calling SDL_InitSubSystem(). Therefore, the
 * two may be used interchangeably. Though for readability of your code
 * SDL_InitSubSystem() might be preferred.
 *
 * The file I/O (for example: SDL_IOFromFile) and threading (SDL_CreateThread)
 * subsystems are initialized by default. Message boxes
 * (SDL_ShowSimpleMessageBox) also attempt to work without initializing the
 * video subsystem, in hopes of being useful in showing an error dialog when
 * SDL_Init fails. You must specifically initialize other subsystems if you
 * use them in your application.
 *
 * Logging (such as SDL_Log) works without initialization, too.
 *
 * `flags` may be any of the following OR'd together:
 *
 * - `SDL_INIT_AUDIO`: audio subsystem; automatically initializes the events
 *   subsystem
 * - `SDL_INIT_VIDEO`: video subsystem; automatically initializes the events
 *   subsystem, should be initialized on the main thread.
 * - `SDL_INIT_JOYSTICK`: joystick subsystem; automatically initializes the
 *   events subsystem
 * - `SDL_INIT_HAPTIC`: haptic (force feedback) subsystem
 * - `SDL_INIT_GAMEPAD`: gamepad subsystem; automatically initializes the
 *   joystick subsystem
 * - `SDL_INIT_EVENTS`: events subsystem
 * - `SDL_INIT_SENSOR`: sensor subsystem; automatically initializes the events
 *   subsystem
 * - `SDL_INIT_CAMERA`: camera subsystem; automatically initializes the events
 *   subsystem
 *
 * Subsystem initialization is ref-counted, you must call SDL_QuitSubSystem()
 * for each SDL_InitSubSystem() to correctly shutdown a subsystem manually (or
 * call SDL_Quit() to force shutdown). If a subsystem is already loaded then
 * this call will increase the ref-count and return.
 *
 * Consider reporting some basic metadata about your application before
 * calling SDL_Init, using either SDL_SetAppMetadata() or
 * SDL_SetAppMetadataProperty().
 *
 * \param flags subsystem initialization flags.
 * \returns true on success or false on failure; call SDL_GetError() for more
 *          information.
 *
 * \threadsafety This function should only be called on the main thread.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_SetAppMetadata
 * \sa SDL_SetAppMetadataProperty
 * \sa SDL_InitSubSystem
 * \sa SDL_Quit
 * \sa SDL_SetMainReady
 * \sa SDL_WasInit
 */
extern SDL_DECLSPEC bool SDLCALL SDL_Init(SDL_InitFlags flags);

/**
 * Compatibility function to initialize the SDL library.
 *
 * This function and SDL_Init() are interchangeable.
 *
 * \param flags any of the flags used by SDL_Init(); see SDL_Init for details.
 * \returns true on success or false on failure; call SDL_GetError() for more
 *          information.
 *
 * \threadsafety This function should only be called on the main thread.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_Init
 * \sa SDL_Quit
 * \sa SDL_QuitSubSystem
 */
extern SDL_DECLSPEC bool SDLCALL SDL_InitSubSystem(SDL_InitFlags flags);

/**
 * Shut down specific SDL subsystems.
 *
 * You still need to call SDL_Quit() even if you close all open subsystems
 * with SDL_QuitSubSystem().
 *
 * \param flags any of the flags used by SDL_Init(); see SDL_Init for details.
 *
 * \threadsafety This function is not thread safe.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_InitSubSystem
 * \sa SDL_Quit
 */
extern SDL_DECLSPEC void SDLCALL SDL_QuitSubSystem(SDL_InitFlags flags);

/**
 * Get a mask of the specified subsystems which are currently initialized.
 *
 * \param flags any of the flags used by SDL_Init(); see SDL_Init for details.
 * \returns a mask of all initialized subsystems if `flags` is 0, otherwise it
 *          returns the initialization status of the specified subsystems.
 *
 * \threadsafety This function is not thread safe.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_Init
 * \sa SDL_InitSubSystem
 */
extern SDL_DECLSPEC SDL_InitFlags SDLCALL SDL_WasInit(SDL_InitFlags flags);

/**
 * Clean up all initialized subsystems.
 *
 * You should call this function even if you have already shutdown each
 * initialized subsystem with SDL_QuitSubSystem(). It is safe to call this
 * function even in the case of errors in initialization.
 *
 * You can use this function with atexit() to ensure that it is run when your
 * application is shutdown, but it is not wise to do this from a library or
 * other dynamically loaded code.
 *
 * \threadsafety This function should only be called on the main thread.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_Init
 * \sa SDL_QuitSubSystem
 */
extern SDL_DECLSPEC void SDLCALL SDL_Quit(void);

/**
 * Return whether this is the main thread.
 *
 * On Apple platforms, the main thread is the thread that runs your program's
 * main() entry point. On other platforms, the main thread is the one that
 * calls SDL_Init(SDL_INIT_VIDEO), which should usually be the one that runs
 * your program's main() entry point. If you are using the main callbacks,
 * SDL_AppInit(), SDL_AppIterate(), and SDL_AppQuit() are all called on the
 * main thread.
 *
 * \returns true if this thread is the main thread, or false otherwise.
 *
 * \threadsafety It is safe to call this function from any thread.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_RunOnMainThread
 */
extern SDL_DECLSPEC bool SDLCALL SDL_IsMainThread(void);

/**
 * Callback run on the main thread.
 *
 * \param userdata an app-controlled pointer that is passed to the callback.
 *
 * \since This datatype is available since SDL 3.2.0.
 *
 * \sa SDL_RunOnMainThread
 */
typedef void (SDLCALL *SDL_MainThreadCallback)(void *userdata);

/**
 * Call a function on the main thread during event processing.
 *
 * If this is called on the main thread, the callback is executed immediately.
 * If this is called on another thread, this callback is queued for execution
 * on the main thread during event processing.
 *
 * Be careful of deadlocks when using this functionality. You should not have
 * the main thread wait for the current thread while this function is being
 * called with `wait_complete` true.
 *
 * \param callback the callback to call on the main thread.
 * \param userdata a pointer that is passed to `callback`.
 * \param wait_complete true to wait for the callback to complete, false to
 *                      return immediately.
 * \returns true on success or false on failure; call SDL_GetError() for more
 *          information.
 *
 * \threadsafety It is safe to call this function from any thread.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_IsMainThread
 */
extern SDL_DECLSPEC bool SDLCALL SDL_RunOnMainThread(SDL_MainThreadCallback callback, void *userdata, bool wait_complete);

/**
 * Specify basic metadata about your app.
 *
 * You can optionally provide metadata about your app to SDL. This is not
 * required, but strongly encouraged.
 *
 * There are several locations where SDL can make use of metadata (an "About"
 * box in the macOS menu bar, the name of the app can be shown on some audio
 * mixers, etc). Any piece of metadata can be left as NULL, if a specific
 * detail doesn't make sense for the app.
 *
 * This function should be called as early as possible, before SDL_Init.
 * Multiple calls to this function are allowed, but various state might not
 * change once it has been set up with a previous call to this function.
 *
 * Passing a NULL removes any previous metadata.
 *
 * This is a simplified interface for the most important information. You can
 * supply significantly more detailed metadata with
 * SDL_SetAppMetadataProperty().
 *
 * \param appname The name of the application ("My Game 2: Bad Guy's
 *                Revenge!").
 * \param appversion The version of the application ("1.0.0beta5" or a git
 *                   hash, or whatever makes sense).
 * \param appidentifier A unique string in reverse-domain format that
 *                      identifies this app ("com.example.mygame2").
 * \returns true on success or false on failure; call SDL_GetError() for more
 *          information.
 *
 * \threadsafety It is safe to call this function from any thread.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_SetAppMetadataProperty
 */
extern SDL_DECLSPEC bool SDLCALL SDL_SetAppMetadata(const char *appname, const char *appversion, const char *appidentifier);

/**
 * Specify metadata about your app through a set of properties.
 *
 * You can optionally provide metadata about your app to SDL. This is not
 * required, but strongly encouraged.
 *
 * There are several locations where SDL can make use of metadata (an "About"
 * box in the macOS menu bar, the name of the app can be shown on some audio
 * mixers, etc). Any piece of metadata can be left out, if a specific detail
 * doesn't make sense for the app.
 *
 * This function should be called as early as possible, before SDL_Init.
 * Multiple calls to this function are allowed, but various state might not
 * change once it has been set up with a previous call to this function.
 *
 * Once set, this metadata can be read using SDL_GetAppMetadataProperty().
 *
 * These are the supported properties:
 *
 * - `SDL_PROP_APP_METADATA_NAME_STRING`: The human-readable name of the
 *   application, like "My Game 2: Bad Guy's Revenge!". This will show up
 *   anywhere the OS shows the name of the application separately from window
 *   titles, such as volume control applets, etc. This defaults to "SDL
 *   Application".
 * - `SDL_PROP_APP_METADATA_VERSION_STRING`: The version of the app that is
 *   running; there are no rules on format, so "1.0.3beta2" and "April 22nd,
 *   2024" and a git hash are all valid options. This has no default.
 * - `SDL_PROP_APP_METADATA_IDENTIFIER_STRING`: A unique string that
 *   identifies this app. This must be in reverse-domain format, like
 *   "com.example.mygame2". This string is used by desktop compositors to
 *   identify and group windows together, as well as match applications with
 *   associated desktop settings and icons. If you plan to package your
 *   application in a container such as Flatpak, the app ID should match the
 *   name of your Flatpak container as well. This has no default.
 * - `SDL_PROP_APP_METADATA_CREATOR_STRING`: The human-readable name of the
 *   creator/developer/maker of this app, like "MojoWorkshop, LLC"
 * - `SDL_PROP_APP_METADATA_COPYRIGHT_STRING`: The human-readable copyright
 *   notice, like "Copyright (c) 2024 MojoWorkshop, LLC" or whatnot. Keep this
 *   to one line, don't paste a copy of a whole software license in here. This
 *   has no default.
 * - `SDL_PROP_APP_METADATA_URL_STRING`: A URL to the app on the web. Maybe a
 *   product page, or a storefront, or even a GitHub repository, for user's
 *   further information This has no default.
 * - `SDL_PROP_APP_METADATA_TYPE_STRING`: The type of application this is.
 *   Currently this string can be "game" for a video game, "mediaplayer" for a
 *   media player, or generically "application" if nothing else applies.
 *   Future versions of SDL might add new types. This defaults to
 *   "application".
 *
 * \param name the name of the metadata property to set.
 * \param value the value of the property, or NULL to remove that property.
 * \returns true on success or false on failure; call SDL_GetError() for more
 *          information.
 *
 * \threadsafety It is safe to call this function from any thread.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_GetAppMetadataProperty
 * \sa SDL_SetAppMetadata
 */
extern SDL_DECLSPEC bool SDLCALL SDL_SetAppMetadataProperty(const char *name, const char *value);

#define SDL_PROP_APP_METADATA_NAME_STRING         "SDL.app.metadata.name"
#define SDL_PROP_APP_METADATA_VERSION_STRING      "SDL.app.metadata.version"
#define SDL_PROP_APP_METADATA_IDENTIFIER_STRING   "SDL.app.metadata.identifier"
#define SDL_PROP_APP_METADATA_CREATOR_STRING      "SDL.app.metadata.creator"
#define SDL_PROP_APP_METADATA_COPYRIGHT_STRING    "SDL.app.metadata.copyright"
#define SDL_PROP_APP_METADATA_URL_STRING          "SDL.app.metadata.url"
#define SDL_PROP_APP_METADATA_TYPE_STRING         "SDL.app.metadata.type"

/**
 * Get metadata about your app.
 *
 * This returns metadata previously set using SDL_SetAppMetadata() or
 * SDL_SetAppMetadataProperty(). See SDL_SetAppMetadataProperty() for the list
 * of available properties and their meanings.
 *
 * \param name the name of the metadata property to get.
 * \returns the current value of the metadata property, or the default if it
 *          is not set, NULL for properties with no default.
 *
 * \threadsafety It is safe to call this function from any thread, although
 *               the string returned is not protected and could potentially be
 *               freed if you call SDL_SetAppMetadataProperty() to set that
 *               property from another thread.
 *
 * \since This function is available since SDL 3.2.0.
 *
 * \sa SDL_SetAppMetadata
 * \sa SDL_SetAppMetadataProperty
 */
extern SDL_DECLSPEC const char * SDLCALL SDL_GetAppMetadataProperty(const char *name);

/* Ends C function definitions when using C++ */
#ifdef __cplusplus
}
#endif
#include <SDL3/SDL_close_code.h>

#endif /* SDL_init_h_ */