Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_BlitSurface.3 @ 3096:ae4e80dbe330
Date: Tue, 17 Feb 2009 14:00:25 +0100
From: Stefan Klug
Subject: [SDL] Possible bug, paused audio playing garbage
On my WinCE device a paused audio device plays random garbage.
This might also be the issue in the thread "sound cracks with SDL_mixer
and AUDIO_S16LSB"
I don't have that much knowledge of the SDL audio part, but the attached
patch fixes it for me, and collapses two redundant ifs.
I'm not sure if this is the correct way to fix this.
Shouldn't the complete stream conversion part of the RunAudio loop be
dependent on the paused property of the device? (not only the call to
(*fill)(udata, istream, istream_len).
Anyways. Would be great if the patch or a fix could find its way to SVN ;-)
Cheers
Stefan
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Mon, 23 Mar 2009 05:21:40 +0000 |
| parents | 546f7c1eb755 |
| children | 1238da4a7112 |
| 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" |
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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 |