Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_SetPalette.3 @ 4158:96ce26f24b01 SDL-1.2
Date: Sun, 7 Sep 2008 15:17:00 +0200
From: c2woody@gmx.net
Subject: [SDL] SDL 1.2 doube free/pointer zeroing missing
Hello,
this is about a crash/debug breakage for the current SDL 1.2
source tree (today's svn checkout, same problem in 1.2.13 and
before as far as relevant).
In some places memory is free()d but the associated pointer
is not zeroed, leading to for example double free()s.
For me this happened because SDL_StopEventThread() was executed
twice (during restart of the subsystems), once for the close
down in SDL_VideoQuit() and once at the startup, right at the
beginning of SDL_StartEventLoop(). Thus the code
SDL_DestroyMutex(SDL_EventQ.lock);
(see SDL_events.c) was called twice and executed the SDL_free(mutex);
twice as well, leading to a crash (msvc 64bit for which it was noticed).
I've tried to check all other occurrences of SDL_free and similar
code in msvc, see the attached patch (udiff against revision 4082).
Non-windows only codepaths have neither been checked nor touched.
Comments/ideas welcome.
Attached patch: NULLifies some pointers after they have been free()d.
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Wed, 12 Nov 2008 17:23:40 +0000 |
| parents | 4e3b250c950e |
| children | 1238da4a7112 |
| rev | line source |
|---|---|
|
181
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Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
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diff
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1 .TH "SDL_SetPalette" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
|
4107
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Erik Heckers fixed bug #493
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3 SDL_SetPalette \- Sets the colors in the palette of an 8-bit surface\&. |
| 0 | 4 .SH "SYNOPSIS" |
| 5 .PP | |
| 6 \fB#include "SDL\&.h" | |
| 7 .sp | |
|
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8 \fBint \fBSDL_SetPalette\fP\fR(\fBSDL_Surface *surface, int flags, SDL_Color *colors, int firstcolor, int ncolors\fR); |
| 0 | 9 .SH "DESCRIPTION" |
| 10 .PP | |
| 11 Sets a portion of the palette for the given 8-bit surface\&. | |
| 12 .PP | |
| 13 Palettized (8-bit) screen surfaces with the \fBSDL_HWPALETTE\fP flag have two palettes, a logical palette that is used for mapping blits to/from the surface and a physical palette (that determines how the hardware will map the colors to the display)\&. \fISDL_BlitSurface\fR always uses the logical palette when blitting surfaces (if it has to convert between surface pixel formats)\&. Because of this, it is often useful to modify only one or the other palette to achieve various special color effects (e\&.g\&., screen fading, color flashes, screen dimming)\&. | |
| 14 .PP | |
| 15 This function can modify either the logical or physical palette by specifing \fBSDL_LOGPAL\fP or \fBSDL_PHYSPAL\fPthe in the \fBflags\fR parameter\&. | |
| 16 .PP | |
| 17 When \fBsurface\fR is the surface associated with the current display, the display colormap will be updated with the requested colors\&. If \fBSDL_HWPALETTE\fP was set in \fISDL_SetVideoMode\fR flags, \fBSDL_SetPalette\fP will always return \fB1\fR, and the palette is guaranteed to be set the way you desire, even if the window colormap has to be warped or run under emulation\&. | |
| 18 .PP | |
| 19 The color components of a \fI\fBSDL_Color\fR\fR structure are 8-bits in size, giving you a total of 256^3=16777216 colors\&. | |
| 20 .SH "RETURN VALUE" | |
| 21 .PP | |
| 22 If \fBsurface\fR is not a palettized surface, this function does nothing, returning \fB0\fR\&. If all of the colors were set as passed to \fBSDL_SetPalette\fP, it will return \fB1\fR\&. If not all the color entries were set exactly as given, it will return \fB0\fR, and you should look at the surface palette to determine the actual color palette\&. | |
| 23 .SH "EXAMPLE" | |
| 24 .PP | |
| 25 .nf | |
| 26 \f(CW /* Create a display surface with a grayscale palette */ | |
| 27 SDL_Surface *screen; | |
| 28 SDL_Color colors[256]; | |
| 29 int i; | |
| 30 \&. | |
| 31 \&. | |
| 32 \&. | |
| 33 /* Fill colors with color information */ | |
| 34 for(i=0;i<256;i++){ | |
| 35 colors[i]\&.r=i; | |
| 36 colors[i]\&.g=i; | |
| 37 colors[i]\&.b=i; | |
| 38 } | |
| 39 | |
| 40 /* Create display */ | |
| 41 screen=SDL_SetVideoMode(640, 480, 8, SDL_HWPALETTE); | |
| 42 if(!screen){ | |
| 43 printf("Couldn\&'t set video mode: %s | |
| 44 ", SDL_GetError()); | |
| 45 exit(-1); | |
| 46 } | |
| 47 | |
| 48 /* Set palette */ | |
| 49 SDL_SetPalette(screen, SDL_LOGPAL|SDL_PHYSPAL, colors, 0, 256); | |
| 50 \&. | |
| 51 \&. | |
| 52 \&. | |
| 53 \&.\fR | |
| 54 .fi | |
| 55 .PP | |
| 56 .SH "SEE ALSO" | |
| 57 .PP | |
| 58 \fISDL_SetColors\fR, \fISDL_SetVideoMode\fR, \fISDL_Surface\fR, \fISDL_Color\fR | |
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Updated from the SDL Documentation Project
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parents:
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diff
changeset
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59 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |