SDL_CreateRGBSurface

Name

SDL_CreateRGBSurface -- Create an empty SDL_Surface

Synopsis

#include "SDL.h"

SDL_Surface *SDL_CreateRGBSurface(Uint32 flags, int width, int height, int bitsPerPixel, 
                                  Uint32 Rmask, Uint32 Gmask, Uint32 Bmask, Uint32 Amask);

Description

Allocate an empty surface (must be called after SDL_SetVideoMode)

If bitsPerPixel is 8 an empty palette is allocated for the surface, otherwise a 'packed-pixel' SDL_PixelFormat is created using the [RGBA]mask's provided (see SDL_PixelFormat). The flags specifies the type of surface that should be created, it is an OR'd combination of the following possible values.

SDL_SWSURFACE

SDL will create the surface in system memory. This improves the performance of pixel level access, however you may not be able to take advantage of some types of hardware blitting.

SDL_HWSURFACE

SDL will attempt to create the surface in video memory. This will allow SDL to take advantage of Video->Video blits (which are often accelerated).

SDL_SRCCOLORKEY

This flag turns on color keying for blits from this surface. If SDL_HWSURFACE is also specified and color keyed blits are hardware-accelerated, then SDL will attempt to place the surface in video memory. If the screen is a hardware surface and color keyed blits are hardware-accelerated then the SDL_HWSURFACE flag will be set. Use SDL_SetColorKey to set or clear this flag after surface creation.

SDL_SRCALPHA

This flag turns on alpha-blending for blits from this surface. If SDL_HWSURFACE is also specified and alpha-blending blits are hardware-accelerated, then the surface will be placed in video memory if possible. If the screen is a hardware surface and alpha-blending blits are hardware-accelerated then the SDL_HWSURFACE flag will be set. Use SDL_SetAlpha to set or clear this flag after surface creation.

[RGBA]mask are the bitmasks used to extract that colour from a pixel. For instance, Rmask being FF000000 means the red data is stored in the most significant byte. Using zeros for the RGB masks sets a default value, based on the depth. (e.g. SDL_CreateRGBSurface(flags,w,h,32,0,0,0,0);) However, using zero for the Amask results in an Amask of 0.

Return Value

Returns the created surface, or NULL upon error.

Example

    /* Create a 32-bit surface with the bytes of each pixel in R,G,B,A order,
       as expected by OpenGL for textures */
    SDL_Surface *surface;
    Uint32 rmask, gmask, bmask, amask;

    /* SDL interprets each pixel as a 32-bit number, so our masks must depend
       on the endianness (byte order) of the machine */
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
    rmask = 0xff000000;
    gmask = 0x00ff0000;
    bmask = 0x0000ff00;
    amask = 0x000000ff;
#else
    rmask = 0x000000ff;
    gmask = 0x0000ff00;
    bmask = 0x00ff0000;
    amask = 0xff000000;
#endif

    surface = SDL_CreateRGBSurface(SDL_SWSURFACE, width, height, 32,
                                   rmask, gmask, bmask, amask);
    if(surface == NULL) {
        fprintf(stderr, "CreateRGBSurface failed: %s\n", SDL_GetError());
        exit(1);
    }

    /* or using the default masks for the depth: */
    surface=SDL_CreateRGBSurface(SDL_SWSURFACE,width,height,32,0,0,0,0);

See Also

SDL_CreateRGBSurfaceFrom, SDL_ConvertSurface, SDL_FreeSurface, SDL_SetVideoMode, SDL_LockSurface, SDL_PixelFormat, SDL_Surface, SDL_SetAlpha, SDL_SetColorKey

SDL_CreateRGBSurface (last edited 2008-04-17 08:18:30 by localhost)