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Date: Mon, 11 Oct 2004 15:17:27 +0300 (EEST) From: Hannu Savolainen Subject: Re: SDL uses obsolete OSS features I did some work on getting OSS to work better with SDL. There have been some problems with select which should be fixed now. I'm having some problems in understanding what is the purpose of the DSP_WaitAudio() routine. I added a return to the very beginning of this routine and commendted out the define for USE_BLOCKING_WRITES. At least lbreakout2 seems to work as well as earlier. The latencies are the same. An ordinary blocking write does exactly the same thing than DSP_WaitAudio does. So I would recommend using the USE_BLOCKING_WRITES approach and removing everything from the DSP_WaitAudio routine. Also enabling USE_BLOCKING_WRITES makes it possible to simplify DSP_PlayAudio() because you don't need to handle the partial writes (the do-while loop). Attached is a patch against SDL-1.2.7. After these changes SDL will use OSS as it's designed to be used (make it as simple as possible). This code should work with all OSS implementations because it uses only the very fundamental features that have been there since the jurassic times.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 12 Nov 2004 21:39:04 +0000
parents e5bc29de3f0a
children 546f7c1eb755
line wrap: on
line source

.TH "SDL_SetColors" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_SetColors\- Sets a portion of the colormap for the given 8-bit surface\&.
.SH "SYNOPSIS"
.PP
\fB#include "SDL\&.h"
.sp
\fBint \fBSDL_SetColors\fP\fR(\fBSDL_Surface *surface, SDL_Color *colors, int firstcolor, int ncolors\fR);
.SH "DESCRIPTION"
.PP
Sets a portion of the colormap for the given 8-bit surface\&.
.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_SetColors\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\&.
.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)\&. \fBSDL_SetColors\fP modifies both palettes (if present), and is equivalent to calling \fISDL_SetPalette\fR with the \fBflags\fR set to \fB(SDL_LOGPAL | SDL_PHYSPAL)\fP\&.
.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_SetColors\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_SetColors(screen, colors, 0, 256);
\&.
\&.
\&.
\&.\fR
.fi
.PP
.SH "SEE ALSO"
.PP
\fI\fBSDL_Color\fR\fR \fI\fBSDL_Surface\fR\fR, \fI\fBSDL_SetPalette\fP\fR, \fI\fBSDL_SetVideoMode\fP\fR
...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01