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te: Thu, 17 Apr 2003 11:25:26 -0700 From: "Jim" Subject: [SDL] Frame buffer patches... Would seem that GCC 3.2.2 promotes all signed values to unsigned if any single vlaue is unsigned in an expression... for instance when calculating an elo touch position....evertyhign is an (int) except for cach_vinfo.xres which is unsigned. THerefore if y ou reverse the SDL_ELO_MIN_X and SDL_ELO_MAX_X values the resulging negative value pegs the expression to it's max. Attached it the accumu lated patch to typecast the unsigned values to (int) - *dx = (cache_vinfo.xres - (cache_vinfo.xres * (input_x - ELO_MIN_X)) / width); + *dx = ((int)cache_vinfo.xres - ((int)cache_vinfo.xres * (input_x - ELO_MIN_X)) / width); and also to provide quite failure to operations which have the screen currently locked... The touch screen I'm using the original values were exactly opposite of any position I touched on the screen - evaluating the math the expr ession SHOULD have handled reversing the min and max values - and after casting the unsigned .xres and .yres to a signed int - worked well. .. Jim
author Sam Lantinga <slouken@libsdl.org>
date Tue, 24 Jan 2006 06:36:43 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_WasInit</TITLE
><META
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><H1
><A
NAME="SDLWASINIT"
></A
>SDL_WasInit</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN617"
></A
><H2
>Name</H2
>SDL_WasInit&nbsp;--&nbsp;Check which subsystems are initialized</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN620"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN621"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>Uint32 <B
CLASS="FSFUNC"
>SDL_WasInit</B
></CODE
>(Uint32 flags);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN627"
></A
><H2
>Description</H2
><P
><TT
CLASS="FUNCTION"
>SDL_WasInit</TT
> allows you to see which SDL subsytems have been <A
HREF="sdlinit.html"
>initialized</A
>. <TT
CLASS="PARAMETER"
><I
>flags</I
></TT
> is a bitwise OR'd combination of the subsystems you wish to check (see <A
HREF="sdlinit.html"
><TT
CLASS="FUNCTION"
>SDL_Init</TT
></A
> for a list of subsystem flags).</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN635"
></A
><H2
>Return Value</H2
><P
><TT
CLASS="FUNCTION"
>SDL_WasInit</TT
> returns a bitwised OR'd combination of the initialized subsystems.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN639"
></A
><H2
>Examples</H2
><PRE
CLASS="PROGRAMLISTING"
>&#13;/* Here are several ways you can use SDL_WasInit() */

/* Get init data on all the subsystems */
Uint32 subsystem_init;

subsystem_init=SDL_WasInit(SDL_INIT_EVERYTHING);

if(subsystem_init&#38;SDL_INIT_VIDEO)
  printf("Video is initialized.\n");
else
  printf("Video is not initialized.\n");



/* Just check for one specfic subsystem */

if(SDL_WasInit(SDL_INIT_VIDEO)!=0)
  printf("Video is initialized.\n");
else
  printf("Video is not initialized.\n");




/* Check for two subsystems */

Uint32 subsystem_mask=SDL_INIT_VIDEO|SDL_INIT_AUDIO;

if(SDL_WasInit(subsystem_mask)==subsystem_mask)
  printf("Video and Audio initialized.\n");
else
  printf("Video and Audio not initialized.\n");&#13;</PRE
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><P
><A
HREF="sdlinit.html"
><TT
CLASS="FUNCTION"
>SDL_Init</TT
></A
>,
<A
HREF="sdlinitsubsystem.html"
><TT
CLASS="FUNCTION"
>SDL_Subsystem</TT
></A
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