Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_BlitSurface.3 @ 641:df178851293b
Date: 28 Jun 2003 22:42:52 +0100
From: Alan Swanson
Subject: Re: [SDL] New XFree 4.3 Video Mode Patch
I have a wee amendment that moves the qsort in set_best_resolution
to only occur after failing to find an exact match only. This would
make absolutely sure we get a user set mode.
While I've never had any problems for my normal resolutions (1280x1024,
1024x768, 800x600 & 640,480) while closely examining the output from
qsort I've noticed it doesn't seem to sort the modes fully. These is
one definite wrong at 1152x768 and a few that just look wrong to me.
From a program (attached) I made to examine this more easily. X has
sorted its mode list using the same method as ours (plus frequency),
and our user modes get inserted without any other movement.
On the patch I've made I've also changed cmpmodes to sort on vertical
resolution and then horizontal. Ie vertical is now most significant
bit.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sat, 28 Jun 2003 21:52:26 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
| rev | line source |
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1 .TH "SDL_BlitSurface" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
| 3 SDL_BlitSurface\- This performs a fast blit from the source surface to the destination surface\&. | |
| 4 .SH "SYNOPSIS" | |
| 5 .PP | |
| 6 \fB#include "SDL\&.h" | |
| 7 .sp | |
| 8 \fBint \fBSDL_BlitSurface\fP\fR(\fBSDL_Surface *src, SDL_Rect *srcrect, SDL_Surface *dst, SDL_Rect *dstrect\fR); | |
| 9 .SH "DESCRIPTION" | |
| 10 .PP | |
| 11 This performs a fast blit from the source surface to the destination surface\&. | |
| 12 .PP | |
| 13 Only the position is used in the \fBdstrect\fR (the width and height are ignored)\&. | |
| 14 .PP | |
| 15 If either \fBsrcrect\fR or \fBdstrect\fR are \fBNULL\fP, the entire surface (\fBsrc\fR or \fBdst\fR) is copied\&. | |
| 16 .PP | |
| 17 The final blit rectangle is saved in \fBdstrect\fR after all clipping is performed (\fBsrcrect\fR is not modified)\&. | |
| 18 .PP | |
| 19 The blit function should not be called on a locked surface\&. | |
| 20 .PP | |
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21 The results of blitting operations vary greatly depending on whether \fBSDL_SRCAPLHA\fP is set or not\&. See \fISDL_SetAlpha\fR for an explaination of how this affects your results\&. Colorkeying and alpha attributes also interact with surface blitting, as the following pseudo-code should hopefully explain\&. |
| 0 | 22 .PP |
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23 .nf |
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24 \f(CWif (source surface has SDL_SRCALPHA set) { |
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25 if (source surface has alpha channel (that is, format->Amask != 0)) |
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26 blit using per-pixel alpha, ignoring any colour key |
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27 else { |
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28 if (source surface has SDL_SRCCOLORKEY set) |
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29 blit using the colour key AND the per-surface alpha value |
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30 else |
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31 blit using the per-surface alpha value |
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32 } |
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33 } else { |
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34 if (source surface has SDL_SRCCOLORKEY set) |
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35 blit using the colour key |
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36 else |
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37 ordinary opaque rectangular blit |
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38 }\fR |
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39 .fi |
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40 .PP |
| 0 | 41 .SH "RETURN VALUE" |
| 42 .PP | |
| 43 If the blit is successful, it returns \fB0\fR, otherwise it returns \fB-1\fR\&. | |
| 44 .PP | |
| 45 If either of the surfaces were in video memory, and the blit returns \fB-2\fR, the video memory was lost, so it should be reloaded with artwork and re-blitted: | |
| 46 .PP | |
| 47 .nf | |
| 48 \f(CW while ( SDL_BlitSurface(image, imgrect, screen, dstrect) == -2 ) { | |
| 49 while ( SDL_LockSurface(image)) < 0 ) | |
| 50 Sleep(10); | |
| 51 -- Write image pixels to image->pixels -- | |
| 52 SDL_UnlockSurface(image); | |
| 53 }\fR | |
| 54 .fi | |
| 55 .PP | |
| 56 This happens under DirectX 5\&.0 when the system switches away from your fullscreen application\&. Locking the surface will also fail until you have access to the video memory again\&. | |
| 57 .SH "SEE ALSO" | |
| 58 .PP | |
| 59 \fI\fBSDL_LockSurface\fP\fR, \fI\fBSDL_FillRect\fP\fR, \fI\fBSDL_Surface\fR\fR, \fI\fBSDL_Rect\fR\fR | |
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60 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |