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view docs/man3/SDL_Rect.3 @ 688:c0522010bb6d
Date: Tue, 12 Aug 2003 14:26:19 +0200 (MEST)
From: "Mattias Engdeg?rd"
Subject: bug in SDL_GetRGB/GetRGBA
There's an embarrassing bug in GetRGB/GetRGBA which apparently has been there
for years. It incorrectly converts colours with < 8 bits/channel.
It came to my attention today in #sdl.
What it does now is (for each channel):
rv = (pixel & fmt->Rmask) >> fmt->Rshift;
*r = (rv << fmt->Rloss) + (rv >> (8 - fmt->Rloss));
which is wrong; the last line should be
*r = (rv << fmt->Rloss) + (rv >> (8 - (fmt->Rloss << 1)));
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Tue, 12 Aug 2003 15:17:20 +0000 |
| parents | e5bc29de3f0a |
| children | 546f7c1eb755 |
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.TH "SDL_Rect" "3" "Tue 11 Sep 2001, 23:01" "SDL" "SDL API Reference" .SH "NAME" SDL_Rect\- Defines a rectangular area .SH "STRUCTURE DEFINITION" .PP .nf \f(CWtypedef struct{ Sint16 x, y; Uint16 w, h; } SDL_Rect;\fR .fi .PP .SH "STRUCTURE DATA" .TP 20 \fBx, y\fR Position of the upper-left corner of the rectangle .TP 20 \fBw, h\fR The width and height of the rectangle .SH "DESCRIPTION" .PP A \fBSDL_Rect\fR defines a rectangular area of pixels\&. It is used by \fI\fBSDL_BlitSurface\fP\fR to define blitting regions and by several other video functions\&. .SH "SEE ALSO" .PP \fI\fBSDL_BlitSurface\fP\fR, \fI\fBSDL_UpdateRect\fP\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 23:01