Mercurial > sdl-ios-xcode
view docs/man3/SDL_SetPalette.3 @ 4168:69bcba65c388 SDL-1.2
Fixed bug #526
Comment #1 From Simon Howard 2009-03-20 16:50:56
Hi,
I'm the author of Chocolate Doom, one of the other source ports that James
mentioned. This is a patch against the current SVN version of SDL 1.2 that
fixes the bug. It has been tested and hopefully should be obviously correct
from examining the changes. I'll give a brief explanation.
When the palette is set with SDL_SetPalette, the IDirectDrawPalette_SetEntries
DirectX function is invoked. However, when this happens, a WM_PALETTECHANGED
message is sent to the window.
A WM_PALETTECHANGED message can also be received if the palette is changed for
some other reason, like if the system palette is changed. Therefore, the
palette change handler (DX5_PaletteChanged) has code to deal with this case.
It distinguishes "expected" palette changes (set with SDL_SetPalette) from
"unexpected" palette changes using the colorchange_expected variable, which is
set before calling IDirectDrawPalette_SetEntries. However, the code to set
this variable is missing in the fullscreen code path. By setting this
variable, the palette change is handled properly and the freezes go away.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Mon, 13 Apr 2009 00:53:12 +0000 |
parents | 4e3b250c950e |
children | 1238da4a7112 |
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.TH "SDL_SetPalette" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_SetPalette \- Sets the colors in the palette of an 8-bit surface\&. .SH "SYNOPSIS" .PP \fB#include "SDL\&.h" .sp \fBint \fBSDL_SetPalette\fP\fR(\fBSDL_Surface *surface, int flags, SDL_Color *colors, int firstcolor, int ncolors\fR); .SH "DESCRIPTION" .PP Sets a portion of the palette for the given 8-bit surface\&. .PP Palettized (8-bit) screen surfaces with the \fBSDL_HWPALETTE\fP 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)\&. \fISDL_BlitSurface\fR 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)\&. .PP This function can modify either the logical or physical palette by specifing \fBSDL_LOGPAL\fP or \fBSDL_PHYSPAL\fPthe in the \fBflags\fR parameter\&. .PP When \fBsurface\fR is the surface associated with the current display, the display colormap will be updated with the requested colors\&. If \fBSDL_HWPALETTE\fP was set in \fISDL_SetVideoMode\fR flags, \fBSDL_SetPalette\fP will always return \fB1\fR, 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\&. .PP The color components of a \fI\fBSDL_Color\fR\fR structure are 8-bits in size, giving you a total of 256^3=16777216 colors\&. .SH "RETURN VALUE" .PP If \fBsurface\fR is not a palettized surface, this function does nothing, returning \fB0\fR\&. If all of the colors were set as passed to \fBSDL_SetPalette\fP, it will return \fB1\fR\&. If not all the color entries were set exactly as given, it will return \fB0\fR, and you should look at the surface palette to determine the actual color palette\&. .SH "EXAMPLE" .PP .nf \f(CW /* 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); \&. \&. \&. \&.\fR .fi .PP .SH "SEE ALSO" .PP \fISDL_SetColors\fR, \fISDL_SetVideoMode\fR, \fISDL_Surface\fR, \fISDL_Color\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01