annotate docs/man3/SDL_VideoModeOK.3 @ 1544:ab1e4c41ab71

Fixed bug #33 Mike Frysinger wrote: > with libsdl-1.2.9, some games (like bomberclone) started > segfaulting in Gentoo [...snip...] > the last change in the last hunk: [...snip...] > if i change the statement to read: > (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures() > bomberclone no longer segfaults on my box Alex Volkov wrote: > The test "(table[which].blit_features & GetBlitFeatures()) == > table[which].blit_features)" is correct, and the previous > "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken. I think there is potentially a slightly different cause of the above problem. During the introduction of the Altivec code, the blit_table struct field 'alpha' got changed from a straightforward enum to a bitmask, which makes perfect sense by itself. However, now the table driven blitter selection code in SDL_CalculateBlitN() can choose the wrong blitters when searching for a NO_ALPHA blitter because of the following code: int a_need = 0; ... (a_need & table[which].alpha) == a_need && When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing alpha channel bits to appear in a non-alpha destination surface. I suppose this could theoretically be an indirect cause of the segfault mentioned above. I *think* this can be fixed by changing to int a_need = NO_ALPHA;
author Sam Lantinga <slouken@libsdl.org>
date Wed, 15 Mar 2006 15:47:49 +0000
parents e5bc29de3f0a
children 546f7c1eb755
rev   line source
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e5bc29de3f0a Updated from the SDL Documentation Project
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1 .TH "SDL_VideoModeOK" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference"
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2 .SH "NAME"
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3 SDL_VideoModeOK\- Check to see if a particular video mode is supported\&.
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4 .SH "SYNOPSIS"
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5 .PP
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6 \fB#include "SDL\&.h"
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7 .sp
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8 \fBint \fBSDL_VideoModeOK\fP\fR(\fBint width, int height, int bpp, Uint32 flags\fR);
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9 .SH "DESCRIPTION"
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10 .PP
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11 \fBSDL_VideoModeOK\fP returns \fB0\fR if the requested mode is not supported under any bit depth, or returns the bits-per-pixel of the closest available mode with the given width, height and requested \fIsurface\fR flags (see \fI\fBSDL_SetVideoMode\fP\fR)\&.
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12 .PP
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13 The bits-per-pixel value returned is only a suggested mode\&. You can usually request and bpp you want when \fIsetting\fR the video mode and SDL will emulate that color depth with a shadow video surface\&.
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14 .PP
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15 The arguments to \fBSDL_VideoModeOK\fP are the same ones you would pass to \fISDL_SetVideoMode\fR
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16 .SH "EXAMPLE"
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17 .PP
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18 .nf
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19 \f(CWSDL_Surface *screen;
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20 Uint32 bpp;
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21 \&.
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22 \&.
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23 \&.
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24 printf("Checking mode 640x480@16bpp\&.
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25 ");
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26 bpp=SDL_VideoModeOK(640, 480, 16, SDL_HWSURFACE);
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27
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28 if(!bpp){
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29 printf("Mode not available\&.
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30 ");
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31 exit(-1);
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32 }
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33
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34 printf("SDL Recommends 640x480@%dbpp\&.
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35 ", bpp);
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36 screen=SDL_SetVideoMode(640, 480, bpp, SDL_HWSURFACE);
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37 \&.
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38 \&.\fR
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39 .fi
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40 .PP
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41 .SH "SEE ALSO"
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42 .PP
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43 \fI\fBSDL_SetVideoMode\fP\fR, \fI\fBSDL_GetVideoInfo\fP\fR
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44 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01