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annotate docs/man3/SDL_BlitSurface.3 @ 4159:a1b03ba2fcd0 SDL-1.2
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author | Sam Lantinga <slouken@libsdl.org> |
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date | Mon, 08 Dec 2008 00:25:42 +0000 |
parents | 4e3b250c950e |
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1 .TH "SDL_BlitSurface" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
0 | 2 .SH "NAME" |
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3 SDL_BlitSurface \- This performs a fast blit from the source surface to the destination surface\&. |
0 | 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 |