Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_BlitSurface.3 @ 571:8e3ce997621c
Date: Thu, 16 Jan 2003 13:48:31 +0200
From: "Mike Gorchak"
Subject: All QNX patches
whole patches concerning QNX. Almost all code has been rewritten by Julian
and me. Added initial support for hw overlays in QNX and many many others
fixes.
P.S. This patches has been reviewed by Dave Rempel from QSSL and included in
SDL 1.2.5 distribution, which coming on 3rd party CD for newest 6.2.1
version of QNX, which will be available soon.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Mon, 20 Jan 2003 01:38:37 +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 |