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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 355632dca928
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<HTML
><HEAD
><TITLE
>SDL_CD</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.64
"><LINK
REL="HOME"
TITLE="SDL Library Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="CD-ROM"
HREF="cdrom.html"><LINK
REL="PREVIOUS"
TITLE="SDL_CDClose"
HREF="sdlcdclose.html"><LINK
REL="NEXT"
TITLE="SDL_CDtrack"
HREF="sdlcdtrack.html"></HEAD
><BODY
CLASS="REFENTRY"
BGCOLOR="#FFF8DC"
TEXT="#000000"
LINK="#0000ee"
VLINK="#551a8b"
ALINK="#ff0000"
><DIV
CLASS="NAVHEADER"
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>SDL Library Documentation</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="sdlcdclose.html"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="sdlcdtrack.html"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
><A
NAME="SDLCD"
>SDL_CD</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN7178"
></A
><H2
>Name</H2
>SDL_CD&nbsp;--&nbsp;CDROM Drive Information</DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7181"
></A
><H2
>Structure Definition</H2
><PRE
CLASS="PROGRAMLISTING"
>typedef struct{
  int id;
  CDstatus status;
  int numtracks;
  int cur_track;
  int cur_frame;
  SDL_CDtrack track[SDL_MAX_TRACKS+1];
} SDL_CD;</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7184"
></A
><H2
>Structure Data</H2
><DIV
CLASS="INFORMALTABLE"
><A
NAME="AEN7186"
></A
><P
></P
><TABLE
BORDER="0"
CLASS="CALSTABLE"
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>id</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Private drive identifier</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>status</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Drive <A
HREF="sdlcdstatus.html"
>status</A
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>numtracks</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Number of tracks on the CD</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>cur_track</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Current track</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>cur_frame</I
></TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Current frame offset within the track</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="STRUCTFIELD"
><I
>track</I
></TT
>[SDL_MAX_TRACKS+1]</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Array of track descriptions. (see <A
HREF="sdlcdtrack.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_CDtrack</SPAN
></A
>)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7216"
></A
><H2
>Description</H2
><P
>An <SPAN
CLASS="STRUCTNAME"
>SDL_CD</SPAN
> structure is returned by <A
HREF="sdlcdopen.html"
><TT
CLASS="FUNCTION"
>SDL_CDOpen</TT
></A
>. It represents an opened CDROM device and stores information on the layout of the tracks on the disc.</P
><P
>A frame is the base data unit of a CD. <TT
CLASS="LITERAL"
>CD_FPS</TT
> frames is equal to 1 second of music. SDL provides two macros for converting between time and frames: <TT
CLASS="LITERAL"
>FRAMES_TO_MSF(f, M,S,F)</TT
> and <TT
CLASS="LITERAL"
>MSF_TO_FRAMES</TT
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7226"
></A
><H2
>Examples</H2
><PRE
CLASS="PROGRAMLISTING"
>int min, sec, frame;
int frame_offset;

FRAMES_TO_MSF(cdrom-&#62;cur_frame, &#38;min, &#38;sec, &#38;frame);
printf("Current Position: %d minutes, %d seconds, %d frames\n", min, sec, frame);

frame_offset=MSF_TO_FRAMES(min, sec, frame);</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN7229"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlcdopen.html"
><TT
CLASS="FUNCTION"
>SDL_CDOpen</TT
></A
>,
<A
HREF="sdlcdtrack.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_CDtrack</SPAN
></A
></P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="sdlcdclose.html"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="sdlcdtrack.html"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>SDL_CDClose</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="cdrom.html"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>SDL_CDtrack</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>