1. 注册新的硬件底层
注意:所有代码基于1.2版本
1). VideoBootStrap
在初始化的时候被直接调用
typedef struct VideoBootStrap {
const char *name;
const char *desc;
int (*available)(void); // 判断设备是否可用
SDL_VideoDevice *(*create)(int devindex); // 创建一个实例
} VideoBootStrap;
2). SDL_VideoDevice
创建一个Video实例， 具体使用的实例为SDL_VideoDevice *current_video = NULL;
依次为：
a). Video
b). 硬件加速
c). gamma支持
d). Opengl支持
e). 窗口管理
f). 光标管理
g). 事件管理
h). 通用数据
i). Opengl的数据
j). 私有数据
k). Free函数
/* The SDL video driver */
typedef struct SDL_VideoDevice SDL_VideoDevice;
#define SDL_VideoSurface (current_video->screen)
#define SDL_ShadowSurface (current_video->shadow)
#define SDL_PublicSurface (current_video->visible)
/* Create a shadow surface if necessary */
/* There are three conditions under which we create a shadow surface:
1. We need a particular bits-per-pixel that we didn't get.
2. We need a hardware palette and didn't get one.
3. We need a software surface and got a hardware surface.
*/
/* Define the SDL video driver structure */
#define _THIS SDL_VideoDevice *_this
#ifndef _STATUS
#define _STATUS SDL_status *status
#endif
struct SDL_VideoDevice {
/* * * */
/* The name of this video driver */
const char *name;
/* * * */
/* Initialization/Query functions */
/* Initialize the native video subsystem, filling 'vformat' with the
"best" display pixel format, returning 0 or -1 if there's an error.
*/
int (*VideoInit)(_THIS, SDL_PixelFormat *vformat);
/* List the available video modes for the given pixel format, sorted
from largest to smallest.
*/
SDL_Rect **(*ListModes)(_THIS, SDL_PixelFormat *format, Uint32 flags);
/* Set the requested video mode, returning a surface which will be
set to the SDL_VideoSurface. The width and height will already
be verified by ListModes(), and the video subsystem is free to
set the mode to a supported bit depth different from the one
specified -- the desired bpp will be emulated with a shadow
surface if necessary. If a new mode is returned, this function
should take care of cleaning up the current mode.
*/
SDL_Surface *(*SetVideoMode)(_THIS, SDL_Surface *current,
int width, int height, int bpp, Uint32 flags);
/* Toggle the fullscreen mode */
int (*ToggleFullScreen)(_THIS, int on);
/* This is called after the video mode has been set, to get the
initial mouse state. It should queue events as necessary to
properly represent the current mouse focus and position.
*/
void (*UpdateMouse)(_THIS);
/* Create a YUV video surface (possibly overlay) of the given
format. The hardware should be able to perform at least 2x
scaling on display.
*/
SDL_Overlay *(*CreateYUVOverlay)(_THIS, int width, int height,
Uint32 format, SDL_Surface *display);
/* Sets the color entries { firstcolor .. (firstcolor+ncolors-1) }
of the physical palette to those in 'colors'. If the device is
using a software palette (SDL_HWPALETTE not set), then the
changes are reflected in the logical palette of the screen
as well.
The return value is 1 if all entries could be set properly
or 0 otherwise.
*/
int (*SetColors)(_THIS, int firstcolor, int ncolors,
SDL_Color *colors);
/* This pointer should exist in the native video subsystem and should
point to an appropriate update function for the current video mode
*/
void (*UpdateRects)(_THIS, int numrects, SDL_Rect *rects);
/* Reverse the effects VideoInit() -- called if VideoInit() fails
or if the application is shutting down the video subsystem.
*/
void (*VideoQuit)(_THIS);
/* * * */
/* Hardware acceleration functions */
/* Information about the video hardware */
SDL_VideoInfo info;
/* The pixel format used when SDL_CreateRGBSurface creates SDL_HWSURFACEs with alpha */
SDL_PixelFormat* displayformatalphapixel;
/* Allocates a surface in video memory */
int (*AllocHWSurface)(_THIS, SDL_Surface *surface);
/* Sets the hardware accelerated blit function, if any, based
on the current flags of the surface (colorkey, alpha, etc.)
*/
int (*CheckHWBlit)(_THIS, SDL_Surface *src, SDL_Surface *dst);
/* Fills a surface rectangle with the given color */
int (*FillHWRect)(_THIS, SDL_Surface *dst, SDL_Rect *rect, Uint32 color);
/* Sets video mem colorkey and accelerated blit function */
int (*SetHWColorKey)(_THIS, SDL_Surface *surface, Uint32 key);
/* Sets per surface hardware alpha value */
int (*SetHWAlpha)(_THIS, SDL_Surface *surface, Uint8 value);
/* Returns a readable/writable surface */
int (*LockHWSurface)(_THIS, SDL_Surface *surface);
void (*UnlockHWSurface)(_THIS, SDL_Surface *surface);
/* Performs hardware flipping */
int (*FlipHWSurface)(_THIS, SDL_Surface *surface);
/* Frees a previously allocated video surface */
void (*FreeHWSurface)(_THIS, SDL_Surface *surface);
/* * * */
/* Gamma support */
Uint16 *gamma;
/* Set the gamma correction directly (emulated with gamma ramps) */
int (*SetGamma)(_THIS, float red, float green, float blue);
/* Get the gamma correction directly (emulated with gamma ramps) */
int (*GetGamma)(_THIS, float *red, float *green, float *blue);
/* Set the gamma ramp */
int (*SetGammaRamp)(_THIS, Uint16 *ramp);
/* Get the gamma ramp */
int (*GetGammaRamp)(_THIS, Uint16 *ramp);
/* * * */
/* OpenGL support */
/* Sets the dll to use for OpenGL and loads it */
int (*GL_LoadLibrary)(_THIS, const char *path);
/* Retrieves the address of a function in the gl library */
void* (*GL_GetProcAddress)(_THIS, const char *proc);
/* Get attribute information from the windowing system. */
int (*GL_GetAttribute)(_THIS, SDL_GLattr attrib, int* value);
/* Make the context associated with this driver current */
int (*GL_MakeCurrent)(_THIS);
/* Swap the current buffers in double buffer mode. */
void (*GL_SwapBuffers)(_THIS);
/* OpenGL functions for SDL_OPENGLBLIT */
#if SDL_VIDEO_OPENGL
#if !defined(__WIN32__)
#define WINAPI
#endif
#define SDL_PROC(ret,func,params) ret (WINAPI *func) params;
#include "SDL_glfuncs.h"
#undef SDL_PROC
/* Texture id */
GLuint texture;
#endif
int is_32bit;
/* * * */
/* Window manager functions */
/* Set the title and icon text */
void (*SetCaption)(_THIS, const char *title, const char *icon);
/* Set the window icon image */
void (*SetIcon)(_THIS, SDL_Surface *icon, Uint8 *mask);
/* Iconify the window.
This function returns 1 if there is a window manager and the
window was actually iconified, it returns 0 otherwise.
*/
int (*IconifyWindow)(_THIS);
/* Grab or ungrab keyboard and mouse input */
SDL_GrabMode (*GrabInput)(_THIS, SDL_GrabMode mode);
/* Get some platform dependent window information */
int (*GetWMInfo)(_THIS, SDL_SysWMinfo *info);
/* * * */
/* Cursor manager functions */
/* Free a window manager cursor
This function can be NULL if CreateWMCursor is also NULL.
*/
void (*FreeWMCursor)(_THIS, WMcursor *cursor);
/* If not NULL, create a black/white window manager cursor */
WMcursor *(*CreateWMCursor)(_THIS,
Uint8 *data, Uint8 *mask, int w, int h, int hot_x, int hot_y);
/* Show the specified cursor, or hide if cursor is NULL */
int (*ShowWMCursor)(_THIS, WMcursor *cursor);
/* Warp the window manager cursor to (x,y)
If NULL, a mouse motion event is posted internally.
*/
void (*WarpWMCursor)(_THIS, Uint16 x, Uint16 y);
/* If not NULL, this is called when a mouse motion event occurs */
void (*MoveWMCursor)(_THIS, int x, int y);
/* Determine whether the mouse should be in relative mode or not.
This function is called when the input grab state or cursor
visibility state changes.
If the cursor is not visible, and the input is grabbed, the
driver can place the mouse in relative mode, which may result
in higher accuracy sampling of the pointer motion.
*/
void (*CheckMouseMode)(_THIS);
/* * * */
/* Event manager functions */
/* Initialize keyboard mapping for this driver */
void (*InitOSKeymap)(_THIS);
/* Handle any queued OS events */
void (*PumpEvents)(_THIS);
/* * * */
/* Data common to all drivers */
SDL_Surface *screen; //SDL_VideoSurface, 等于在私有的XXX_SetVideoMode的返回值
SDL_Surface *shadow; //SDL_ShadowSurface
SDL_Surface *visible; //SDL_PublicSurface 指向SDL_ShadowSurface或者SDL_VideoSurface
SDL_Palette *physpal; /* physical palette, if != logical palette */
SDL_Color *gammacols; /* gamma-corrected colours, or NULL */
char *wm_title;
char *wm_icon;
int offset_x;
int offset_y;
SDL_GrabMode input_grab;
/* Driver information flags */
int handles_any_size; /* Driver handles any size video mode */
/* * * */
/* Data used by the GL drivers */
struct {
int red_size;
int green_size;
int blue_size;
int alpha_size;
int depth_size;
int buffer_size;
int stencil_size;
int double_buffer;
int accum_red_size;
int accum_green_size;
int accum_blue_size;
int accum_alpha_size;
int stereo;
int multisamplebuffers;
int multisamplesamples;
int accelerated;
int swap_control;
int driver_loaded;
char driver_path[256];
void* dll_handle;
} gl_config;
/* * * */
/* Data private to this driver */
struct SDL_PrivateVideoData *hidden;
struct SDL_PrivateGLData *gl_data;
/* * * */
/* The function used to dispose of this structure */
void (*free)(_THIS);
};
#undef _THIS
其中的Videoinfo
/** Useful for determining the video hardware capabilities */
typedef struct SDL_VideoInfo {
Uint32 hw_available :1; /**< Flag: Can you create hardware surfaces? */
Uint32 wm_available :1; /**< Flag: Can you talk to a window manager? */
Uint32 UnusedBits1 :6;
Uint32 UnusedBits2 :1;
Uint32 blit_hw :1; /**< Flag: Accelerated blits HW --> HW */
Uint32 blit_hw_CC :1; /**< Flag: Accelerated blits with Colorkey */
Uint32 blit_hw_A :1; /**< Flag: Accelerated blits with Alpha */
Uint32 blit_sw :1; /**< Flag: Accelerated blits SW --> HW */
Uint32 blit_sw_CC :1; /**< Flag: Accelerated blits with Colorkey */
Uint32 blit_sw_A :1; /**< Flag: Accelerated blits with Alpha */
Uint32 blit_fill :1; /**< Flag: Accelerated color fill */
Uint32 UnusedBits3 :16;
Uint32 video_mem; /**< The total amount of video memory (in K) */
SDL_PixelFormat *vfmt; /**< Value: The format of the video surface */
int current_w; /**< Value: The current video mode width */
int current_h; /**< Value: The current video mode height */
} SDL_VideoInfo;
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