sdl_setcolorkey.3

MPEG-4编解码的实现(包括MPEG4视音频编解码)

.TH "SDL_SetColorKey" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" 
.SH "NAME"
SDL_SetColorKey\- Sets the color key (transparent pixel) in a blittable surface and RLE acceleration\&.
.SH "SYNOPSIS"
.PP
\fB#include "SDL\&.h"
.sp
\fBint \fBSDL_SetColorKey\fP\fR(\fBSDL_Surface *surface, Uint32 flag, Uint32 key\fR);
.SH "DESCRIPTION"
.PP
 Sets the color key (transparent pixel) in a blittable surface and enables or disables RLE blit acceleration\&.
.PP
RLE acceleration can substantially speed up blitting of images with large horizontal runs of transparent pixels (i\&.e\&., pixels that match the \fBkey\fR value)\&. The \fBkey\fR must be of the same pixel format as the \fBsurface\fR, \fI\fBSDL_MapRGB\fP\fR is often useful for obtaining an acceptable value\&.
.PP
If \fBflag\fR is \fBSDL_SRCCOLORKEY\fP then \fBkey\fR is the transparent pixel value in the source image of a blit\&.
.PP
If \fBflag\fR is OR\&'d with \fBSDL_RLEACCEL\fP then the surface will be draw using RLE acceleration when drawn with \fISDL_BlitSurface\fR\&. The surface will actually be encoded for RLE acceleration the first time \fISDL_BlitSurface\fR or \fISDL_DisplayFormat\fR is called on the surface\&.
.PP
If \fBflag\fR is 0, this function clears any current color key\&.
.SH "RETURN VALUE"
.PP
This function returns \fB0\fR, or \fB-1\fR if there was an error\&.
.SH "SEE ALSO"
.PP
\fI\fBSDL_BlitSurface\fP\fR, \fI\fBSDL_DisplayFormat\fP\fR, \fI\fBSDL_MapRGB\fP\fR, \fI\fBSDL_SetAlpha\fP\fR
...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01