SDL_SetPalette — Sets the colors in the palette of an 8-bit surface.
#include "SDL.h"
int
SDL_SetPalette( |
SDL_Surface * | surface, |
int | flags, | |
SDL_Color * | colors, | |
int | firstcolor, | |
int | ncolors) ; |
Sets a portion of the palette for the given 8-bit surface.
Palettized (8-bit) screen surfaces with the SDL_HWPALETTE
flag have two palettes, a
logical palette that is used for mapping blits to/from the
surface and a physical palette (that determines how the
hardware will map the colors to the display). SDL_BlitSurface
always uses the logical
palette when blitting surfaces (if it has to convert between
surface pixel formats). Because of this, it is often useful
to modify only one or the other palette to achieve various
special color effects (e.g., screen fading, color flashes,
screen dimming).
This function can modify either the logical or physical
palette by specifing SDL_LOGPAL
or SDL_PHYSPAL
the in the
flags
parameter.
When surface
is
the surface associated with the current display, the display
colormap will be updated with the requested colors. If
SDL_HWPALETTE
was set in
SDL_SetVideoMode
flags,
SDL_SetPalette
will always
return 1
, and the palette is
guaranteed to be set the way you desire, even if the window
colormap has to be warped or run under emulation.
The color components of a SDL_Color structure are 8-bits in size, giving you a total of 256^3=16777216 colors.
If surface
is not
a palettized surface, this function does nothing, returning
0
. If all of the colors were
set as passed to SDL_SetPalette
, it will return 1
. If not all the color entries were set
exactly as given, it will return 0
, and you should look at the surface
palette to determine the actual color palette.
/* Create a display surface with a grayscale palette */ SDL_Surface *screen; SDL_Color colors[256]; int i; . . . /* Fill colors with color information */ for(i=0;i<256;i++){ colors[i].r=i; colors[i].g=i; colors[i].b=i; } /* Create display */ screen=SDL_SetVideoMode(640, 480, 8, SDL_HWPALETTE); if(!screen){ printf("Couldn't set video mode: %s ", SDL_GetError()); exit(-1); } /* Set palette */ SDL_SetPalette(screen, SDL_LOGPAL|SDL_PHYSPAL, colors, 0, 256); . . . .
SDL_SetColors
, SDL_SetVideoMode
, SDL_Surface, SDL_Color
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This manual page is taken from the SDL library, licensed under GNU LGPL. |