SDL2学习(二):常用枚举值和函数

1. 高频枚举值或结构体

1.1 SDL_WindowFlags

/**
 *  \brief The flags on a window
 *
 *  \sa SDL_GetWindowFlags()
 */
typedef enum
{
    /* !!! FIXME: change this to name = (1<<x). */
    SDL_WINDOW_FULLSCREEN = 0x00000001,         /**< fullscreen window */
    SDL_WINDOW_OPENGL = 0x00000002,             /**< window usable with OpenGL context */
    SDL_WINDOW_SHOWN = 0x00000004,              /**< window is visible */
    SDL_WINDOW_HIDDEN = 0x00000008,             /**< window is not visible */
    SDL_WINDOW_BORDERLESS = 0x00000010,         /**< no window decoration */
    SDL_WINDOW_RESIZABLE = 0x00000020,          /**< window can be resized */
    SDL_WINDOW_MINIMIZED = 0x00000040,          /**< window is minimized */
    SDL_WINDOW_MAXIMIZED = 0x00000080,          /**< window is maximized */
    SDL_WINDOW_INPUT_GRABBED = 0x00000100,      /**< window has grabbed input focus */
    SDL_WINDOW_INPUT_FOCUS = 0x00000200,        /**< window has input focus */
    SDL_WINDOW_MOUSE_FOCUS = 0x00000400,        /**< window has mouse focus */
    SDL_WINDOW_FULLSCREEN_DESKTOP = ( SDL_WINDOW_FULLSCREEN | 0x00001000 ),
    SDL_WINDOW_FOREIGN = 0x00000800,            /**< window not created by SDL */
    SDL_WINDOW_ALLOW_HIGHDPI = 0x00002000,      /**< window should be created in high-DPI mode if supported.
                                                     On macOS NSHighResolutionCapable must be set true in the
                                                     application's Info.plist for this to have any effect. */
    SDL_WINDOW_MOUSE_CAPTURE = 0x00004000,      /**< window has mouse captured (unrelated to INPUT_GRABBED) */
    SDL_WINDOW_ALWAYS_ON_TOP = 0x00008000,      /**< window should always be above others */
    SDL_WINDOW_SKIP_TASKBAR  = 0x00010000,      /**< window should not be added to the taskbar */
    SDL_WINDOW_UTILITY       = 0x00020000,      /**< window should be treated as a utility window */
    SDL_WINDOW_TOOLTIP       = 0x00040000,      /**< window should be treated as a tooltip */
    SDL_WINDOW_POPUP_MENU    = 0x00080000,      /**< window should be treated as a popup menu */
    SDL_WINDOW_VULKAN        = 0x10000000       /**< window usable for Vulkan surface */
} SDL_WindowFlags;

这个枚举值主要是和窗口相关的属性。

1.2 SDL_RendererFlags

typedef enum
{
    SDL_RENDERER_SOFTWARE = 0x00000001,         /**< The renderer is a software fallback */
    SDL_RENDERER_ACCELERATED = 0x00000002,      /**< The renderer uses hardware
                                                     acceleration */
    SDL_RENDERER_PRESENTVSYNC = 0x00000004,     /**< Present is synchronized
                                                     with the refresh rate */
    SDL_RENDERER_TARGETTEXTURE = 0x00000008     /**< The renderer supports
                                                     rendering to texture */
} SDL_RendererFlags;

和SDL_Renderer属性相关。

1.3 SDL_EventType

/**
 * \brief The types of events that can be delivered.
 */
typedef enum
{
    SDL_FIRSTEVENT     = 0,     /**< Unused (do not remove) */

    /* Application events */
    SDL_QUIT           = 0x100, /**< User-requested quit */

    /* These application events have special meaning on iOS, see README-ios.md for details */
    SDL_APP_TERMINATING,        /**< The application is being terminated by the OS
                                     Called on iOS in applicationWillTerminate()
                                     Called on Android in onDestroy()
                                */
    SDL_APP_LOWMEMORY,          /**< The application is low on memory, free memory if possible.
                                     Called on iOS in applicationDidReceiveMemoryWarning()
                                     Called on Android in onLowMemory()
                                */
    SDL_APP_WILLENTERBACKGROUND, /**< The application is about to enter the background
                                     Called on iOS in applicationWillResignActive()
                                     Called on Android in onPause()
                                */
    SDL_APP_DIDENTERBACKGROUND, /**< The application did enter the background and may not get CPU for some time
                                     Called on iOS in applicationDidEnterBackground()
                                     Called on Android in onPause()
                                */
    SDL_APP_WILLENTERFOREGROUND, /**< The application is about to enter the foreground
                                     Called on iOS in applicationWillEnterForeground()
                                     Called on Android in onResume()
                                */
    SDL_APP_DIDENTERFOREGROUND, /**< The application is now interactive
                                     Called on iOS in applicationDidBecomeActive()
                                     Called on Android in onResume()
                                */

    /* Display events */
    SDL_DISPLAYEVENT   = 0x150,  /**< Display state change */

    /* Window events */
    SDL_WINDOWEVENT    = 0x200, /**< Window state change */
    SDL_SYSWMEVENT,             /**< System specific event */

    /* Keyboard events */
    SDL_KEYDOWN        = 0x300, /**< Key pressed */
    SDL_KEYUP,                  /**< Key released */
    SDL_TEXTEDITING,            /**< Keyboard text editing (composition) */
    SDL_TEXTINPUT,              /**< Keyboard text input */
    SDL_KEYMAPCHANGED,          /**< Keymap changed due to a system event such as an
                                     input language or keyboard layout change.
                                */

    /* Mouse events */
    SDL_MOUSEMOTION    = 0x400, /**< Mouse moved */
    SDL_MOUSEBUTTONDOWN,        /**< Mouse button pressed */
    SDL_MOUSEBUTTONUP,          /**< Mouse button released */
    SDL_MOUSEWHEEL,             /**< Mouse wheel motion */

    /* Joystick events */
    SDL_JOYAXISMOTION  = 0x600, /**< Joystick axis motion */
    SDL_JOYBALLMOTION,          /**< Joystick trackball motion */
    SDL_JOYHATMOTION,           /**< Joystick hat position change */
    SDL_JOYBUTTONDOWN,          /**< Joystick button pressed */
    SDL_JOYBUTTONUP,            /**< Joystick button released */
    SDL_JOYDEVICEADDED,         /**< A new joystick has been inserted into the system */
    SDL_JOYDEVICEREMOVED,       /**< An opened joystick has been removed */

    /* Game controller events */
    SDL_CONTROLLERAXISMOTION  = 0x650, /**< Game controller axis motion */
    SDL_CONTROLLERBUTTONDOWN,          /**< Game controller button pressed */
    SDL_CONTROLLERBUTTONUP,            /**< Game controller button released */
    SDL_CONTROLLERDEVICEADDED,         /**< A new Game controller has been inserted into the system */
    SDL_CONTROLLERDEVICEREMOVED,       /**< An opened Game controller has been removed */
    SDL_CONTROLLERDEVICEREMAPPED,      /**< The controller mapping was updated */

    /* Touch events */
    SDL_FINGERDOWN      = 0x700,
    SDL_FINGERUP,
    SDL_FINGERMOTION,

    /* Gesture events */
    SDL_DOLLARGESTURE   = 0x800,
    SDL_DOLLARRECORD,
    SDL_MULTIGESTURE,

    /* Clipboard events */
    SDL_CLIPBOARDUPDATE = 0x900, /**< The clipboard changed */

    /* Drag and drop events */
    SDL_DROPFILE        = 0x1000, /**< The system requests a file open */
    SDL_DROPTEXT,                 /**< text/plain drag-and-drop event */
    SDL_DROPBEGIN,                /**< A new set of drops is beginning (NULL filename) */
    SDL_DROPCOMPLETE,             /**< Current set of drops is now complete (NULL filename) */

    /* Audio hotplug events */
    SDL_AUDIODEVICEADDED = 0x1100, /**< A new audio device is available */
    SDL_AUDIODEVICEREMOVED,        /**< An audio device has been removed. */

    /* Sensor events */
    SDL_SENSORUPDATE = 0x1200,     /**< A sensor was updated */

    /* Render events */
    SDL_RENDER_TARGETS_RESET = 0x2000, /**< The render targets have been reset and their contents need to be updated */
    SDL_RENDER_DEVICE_RESET, /**< The device has been reset and all textures need to be recreated */

    /** Events ::SDL_USEREVENT through ::SDL_LASTEVENT are for your use,
     *  and should be allocated with SDL_RegisterEvents()
     */
    SDL_USEREVENT    = 0x8000,

    /**
     *  This last event is only for bounding internal arrays
     */
    SDL_LASTEVENT    = 0xFFFF
} SDL_EventType;

这个就是SDL事件代号，SDL_Event结构体中的type属性。

1.4 SDL_WindowEventID

/**
 *  \brief Event subtype for window events
 */
typedef enum
{
    SDL_WINDOWEVENT_NONE,           /**< Never used */
    SDL_WINDOWEVENT_SHOWN,          /**< Window has been shown */
    SDL_WINDOWEVENT_HIDDEN,         /**< Window has been hidden */
    SDL_WINDOWEVENT_EXPOSED,        /**< Window has been exposed and should be
                                         redrawn */
    SDL_WINDOWEVENT_MOVED,          /**< Window has been moved to data1, data2
                                     */
    SDL_WINDOWEVENT_RESIZED,        /**< Window has been resized to data1xdata2 */
    SDL_WINDOWEVENT_SIZE_CHANGED,   /**< The window size has changed, either as
                                         a result of an API call or through the
                                         system or user changing the window size. */
    SDL_WINDOWEVENT_MINIMIZED,      /**< Window has been minimized */
    SDL_WINDOWEVENT_MAXIMIZED,      /**< Window has been maximized */
    SDL_WINDOWEVENT_RESTORED,       /**< Window has been restored to normal size
                                         and position */
    SDL_WINDOWEVENT_ENTER,          /**< Window has gained mouse focus */
    SDL_WINDOWEVENT_LEAVE,          /**< Window has lost mouse focus */
    SDL_WINDOWEVENT_FOCUS_GAINED,   /**< Window has gained keyboard focus */
    SDL_WINDOWEVENT_FOCUS_LOST,     /**< Window has lost keyboard focus */
    SDL_WINDOWEVENT_CLOSE,          /**< The window manager requests that the window be closed */
    SDL_WINDOWEVENT_TAKE_FOCUS,     /**< Window is being offered a focus (should SetWindowInputFocus() on itself or a subwindow, or ignore) */
    SDL_WINDOWEVENT_HIT_TEST        /**< Window had a hit test that wasn't SDL_HITTEST_NORMAL. */
} SDL_WindowEventID;

窗口事件代码。

1.5 SDL_Event

/**
 *  \brief General event structure
 */
typedef union SDL_Event
{
    Uint32 type;                    /**< Event type, shared with all events */
    SDL_CommonEvent common;         /**< Common event data */
    SDL_DisplayEvent display;       /**< Window event data */
    SDL_WindowEvent window;         /**< Window event data */
    SDL_KeyboardEvent key;          /**< Keyboard event data */
    SDL_TextEditingEvent edit;      /**< Text editing event data */
    SDL_TextInputEvent text;        /**< Text input event data */
    SDL_MouseMotionEvent motion;    /**< Mouse motion event data */
    SDL_MouseButtonEvent button;    /**< Mouse button event data */
    SDL_MouseWheelEvent wheel;      /**< Mouse wheel event data */
    SDL_JoyAxisEvent jaxis;         /**< Joystick axis event data */
    SDL_JoyBallEvent jball;         /**< Joystick ball event data */
    SDL_JoyHatEvent jhat;           /**< Joystick hat event data */
    SDL_JoyButtonEvent jbutton;     /**< Joystick button event data */
    SDL_JoyDeviceEvent jdevice;     /**< Joystick device change event data */
    SDL_ControllerAxisEvent caxis;      /**< Game Controller axis event data */
    SDL_ControllerButtonEvent cbutton;  /**< Game Controller button event data */
    SDL_ControllerDeviceEvent cdevice;  /**< Game Controller device event data */
    SDL_AudioDeviceEvent adevice;   /**< Audio device event data */
    SDL_SensorEvent sensor;         /**< Sensor event data */
    SDL_QuitEvent quit;             /**< Quit request event data */
    SDL_UserEvent user;             /**< Custom event data */
    SDL_SysWMEvent syswm;           /**< System dependent window event data */
    SDL_TouchFingerEvent tfinger;   /**< Touch finger event data */
    SDL_MultiGestureEvent mgesture; /**< Gesture event data */
    SDL_DollarGestureEvent dgesture; /**< Gesture event data */
    SDL_DropEvent drop;             /**< Drag and drop event data */

    /* This is necessary for ABI compatibility between Visual C++ and GCC
       Visual C++ will respect the push pack pragma and use 52 bytes for
       this structure, and GCC will use the alignment of the largest datatype
       within the union, which is 8 bytes.

       So... we'll add padding to force the size to be 56 bytes for both.
    */
    Uint8 padding[56];
} SDL_Event;

当然SDL2还有很多其他的结构体或枚举值，这里只是列出初学者很常见的几个。

2. 窗口管理相关的函数

初学时，接触比较多的是窗口相关的函数，但是数量也是挺多的。

SDL_Init

说明：初始化SDL库，内部调用了SDL_InitSubSystem()。在进行任何SDL操作前，必须先调用此函数初始化。

参数：falgs标识子系统编号。

返回值：成功返回0,失败返回负值

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

/**
 *  \name SDL_INIT_*
 *
 *  These are the flags which may be passed to SDL_Init().  You should
 *  specify the subsystems which you will be using in your application.
 */
/* @{ */
#define SDL_INIT_TIMER          0x00000001u
#define SDL_INIT_AUDIO          0x00000010u
#define SDL_INIT_VIDEO          0x00000020u  /**< SDL_INIT_VIDEO implies SDL_INIT_EVENTS */
#define SDL_INIT_JOYSTICK       0x00000200u  /**< SDL_INIT_JOYSTICK implies SDL_INIT_EVENTS */
#define SDL_INIT_HAPTIC         0x00001000u
#define SDL_INIT_GAMECONTROLLER 0x00002000u  /**< SDL_INIT_GAMECONTROLLER implies SDL_INIT_JOYSTICK */
#define SDL_INIT_EVENTS         0x00004000u
#define SDL_INIT_SENSOR         0x00008000u
#define SDL_INIT_NOPARACHUTE    0x00100000u  /**< compatibility; this flag is ignored. */
#define SDL_INIT_EVERYTHING ( \
                SDL_INIT_TIMER | SDL_INIT_AUDIO | SDL_INIT_VIDEO | SDL_INIT_EVENTS | \
                SDL_INIT_JOYSTICK | SDL_INIT_HAPTIC | SDL_INIT_GAMECONTROLLER | SDL_INIT_SENSOR \
            )
/* @} */

/**
 *  This function initializes  the subsystems specified by \c flags
 */
extern DECLSPEC int SDLCALL SDL_Init(Uint32 flags);

SDL_Quit

说明：清理初始化的子系统

参数：无

返回值：无

 *  This function cleans up all initialized subsystems. You should
 *  call it upon all exit conditions.
 */
extern DECLSPEC void SDLCALL SDL_Quit(void);

SDL_CreateWindow

说明：创建一个窗口

参数：  title：窗口标题； x：SDL_WINDOWPOS_CENTERED(居中)或SDL_WINDOWPOS_UNDEFINED(未定义)；y：同x； w：窗口宽度； h：窗口高度； flags：即上面的SDL_WindowFlags。

返回值：窗口SDL_window指针

/**
 *  \brief Create a window with the specified position, dimensions, and flags.
 *
 *  \param title The title of the window, in UTF-8 encoding.
 *  \param x     The x position of the window, ::SDL_WINDOWPOS_CENTERED, or
 *               ::SDL_WINDOWPOS_UNDEFINED.
 *  \param y     The y position of the window, ::SDL_WINDOWPOS_CENTERED, or
 *               ::SDL_WINDOWPOS_UNDEFINED.
 *  \param w     The width of the window, in screen coordinates.
 *  \param h     The height of the window, in screen coordinates.
 *  \param flags The flags for the window, a mask of any of the following:
 *               ::SDL_WINDOW_FULLSCREEN,    ::SDL_WINDOW_OPENGL,
 *               ::SDL_WINDOW_HIDDEN,        ::SDL_WINDOW_BORDERLESS,
 *               ::SDL_WINDOW_RESIZABLE,     ::SDL_WINDOW_MAXIMIZED,
 *               ::SDL_WINDOW_MINIMIZED,     ::SDL_WINDOW_INPUT_GRABBED,
 *               ::SDL_WINDOW_ALLOW_HIGHDPI, ::SDL_WINDOW_VULKAN.
 *
 *  \return The created window, or NULL if window creation failed.
 *
 *  If the window is created with the SDL_WINDOW_ALLOW_HIGHDPI flag, its size
 *  in pixels may differ from its size in screen coordinates on platforms with
 *  high-DPI support (e.g. iOS and Mac OS X). Use SDL_GetWindowSize() to query
 *  the client area's size in screen coordinates, and SDL_GL_GetDrawableSize(),
 *  SDL_Vulkan_GetDrawableSize(), or SDL_GetRendererOutputSize() to query the
 *  drawable size in pixels.
 *
 *  If the window is created with any of the SDL_WINDOW_OPENGL or
 *  SDL_WINDOW_VULKAN flags, then the corresponding LoadLibrary function
 *  (SDL_GL_LoadLibrary or SDL_Vulkan_LoadLibrary) is called and the
 *  corresponding UnloadLibrary function is called by SDL_DestroyWindow().
 *
 *  If SDL_WINDOW_VULKAN is specified and there isn't a working Vulkan driver,
 *  SDL_CreateWindow() will fail because SDL_Vulkan_LoadLibrary() will fail.
 *
 *  \note On non-Apple devices, SDL requires you to either not link to the
 *        Vulkan loader or link to a dynamic library version. This limitation
 *        may be removed in a future version of SDL.
 *
 *  \sa SDL_DestroyWindow()
 *  \sa SDL_GL_LoadLibrary()
 *  \sa SDL_Vulkan_LoadLibrary()
 */
extern DECLSPEC SDL_Window * SDLCALL SDL_CreateWindow(const char *title,
                                                      int x, int y, int w,
                                                      int h, Uint32 flags);

SDL_DestroyWindow

说明：销毁一个窗口

参数：窗口指针

返回值：无

SDL_CreateWindowFrom

2.5 SDL_GetWindowID

2.6 SDL_GetWindowFromID

SDL_GetWindowFlags

SDL_SetWindowTitle

SDL_GetWindowTitle

SDL_SetWindowIcon

SDL_SetWindowData

SDL_RaiseWindow

SDL_GetWindowPosition_SDL_GetWindowGrab

SDL_GetWindowSize

SDL_HideWindow

SDL_MaximizeWindow

SDL_MinimizeWindow

SDL_RaiseWindow

SDL_SetWindowFullscreen

SDL_SetWindowGrab

SDL_SetWindowSize

SDL_UpdateWindowSurfaceRects

SDL_CreateRenderer

SDL_GetRenderer

SDL_DestroyRenderer

SDL_CreateTexture

SDL_DestroyTexture

。。。

还有很多，就不一一列出来，要用时可以再去查看头文件说明。