Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_BlitSurface.3 @ 1748:5e86e34453d4
------- Comment #1 From Max Horn 2006-04-17 03:08 [reply] -------
Created an attachment (id=106) [edit]
Patch for src/joystick/win32/SDL_mmjoystick.c
I am not even a Windows user, so take the following with a grain of salt:
SDL_mmjoystick.c has a function GetJoystickName which obtains the joystick
name by looking at the registry. The way it does that seems very fishy to me.
Namely, it uses the parameter "index" to construct a registry value name (BTW,
those variables used in the code are really badly named). The value of "index"
in turn equals the current value of "numdevs", as called from
SDL_SYS_JoystickInit.
I read through the MSDN docs at
<http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/dnarinput/html/msdn_extdirect.asp>,
and I believe the simple fix is to replace line 183 of said file
SYS_JoystickName[numdevs] = GetJoystickName(numdevs, joycaps.szRegKey);
by the following:
SYS_JoystickName[numdevs] = GetJoystickName(SYS_JoystickID[i],
joycaps.szRegKey);
However, that is only *hiding* the real issue. Problem is, the list of
joysticks as returned by windows may contains "gaps", and the code deals
incorrectly with that. Namely those gaps occur if joysticks are
removed/(re)added, as the reporter observed.
The attached patch fixes this and another (off-by-one) issue in the code. But
since I have no Windows machine, I can't even test-compile it, so use with
caution.
author | Sam Lantinga <slouken@libsdl.org> |
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date | Sat, 29 Apr 2006 20:22:31 +0000 |
parents | e5bc29de3f0a |
children | 546f7c1eb755 |
rev | line source |
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181
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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 | |
181
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60 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |