Mercurial > sdl-ios-xcode
annotate docs/man3/SDL_MapRGBA.3 @ 997:3bf4103b2b89
Date: Sat, 27 Nov 2004 13:35:43 +0100
From: "Martin Bickel"
Subject: [SDL] Patch: fixing uninitilized palette
while running Valgrind over my application I found the following
problem in SDL:
The function MapNto1 allocates SDL_Color colors[256] but does not
initialize it.
SDL_DitherColors is then called which initialized the r, g and b
component, but not the 'unused' component of each color.
When Map1to1 is called from MapNto1, it runs a memcmp on the colors,
which also evaluates the unused component and therefor returns
differences much more often than necessary.
So the 'unused' component of SDL_Color should be initialized. This
patch does this by calling memset for the whole array in MapNto1 .
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Tue, 30 Nov 2004 14:28:20 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
| rev | line source |
|---|---|
|
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
1 .TH "SDL_MapRGBA" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
| 3 SDL_MapRGBA\- Map a RGBA color value to a pixel format\&. | |
| 4 .SH "SYNOPSIS" | |
| 5 .PP | |
| 6 \fB#include "SDL\&.h" | |
| 7 .sp | |
| 8 \fBUint32 \fBSDL_MapRGBA\fP\fR(\fBSDL_PixelFormat *fmt, Uint8 r, Uint8 g, Uint8 b, Uint8 a\fR); | |
| 9 .SH "DESCRIPTION" | |
| 10 .PP | |
| 11 Maps the RGBA color value to the specified pixel format and returns the pixel value as a 32-bit int\&. | |
| 12 .PP | |
| 13 If the format has a palette (8-bit) the index of the closest matching color in the palette will be returned\&. | |
| 14 .PP | |
| 15 If the specified pixel format has no alpha component the alpha value will be ignored (as it will be in formats with a palette)\&. | |
| 16 .SH "RETURN VALUE" | |
| 17 .PP | |
| 18 A pixel value best approximating the given RGBA color value for a given pixel format\&. If the pixel format bpp (color depth) is less than 32-bpp then the unused upper bits of the return value can safely be ignored (e\&.g\&., with a 16-bpp format the return value can be assigned to a \fBUint16\fP, and similarly a \fBUint8\fP for an 8-bpp format)\&. | |
| 19 .SH "SEE ALSO" | |
| 20 .PP | |
| 21 \fISDL_GetRGB\fR, \fISDL_GetRGBA\fR, \fISDL_MapRGB\fR, \fISDL_PixelFormat\fR | |
|
181
e5bc29de3f0a
Updated from the SDL Documentation Project
Sam Lantinga <slouken@libsdl.org>
parents:
55
diff
changeset
|
22 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01 |