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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_SetClipRect</TITLE
><META
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><H1
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>SDL_SetClipRect</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN2199"
></A
><H2
>Name</H2
>SDL_SetClipRect&nbsp;--&nbsp;Sets the clipping rectangle for a surface.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN2202"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
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></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void <B
CLASS="FSFUNC"
>SDL_SetClipRect</B
></CODE
>(SDL_Surface *surface, SDL_Rect *rect);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN2209"
></A
><H2
>Description</H2
><P
>Sets the clipping rectangle for a surface.  When this surface is the
destination of a blit, only the area within the clip rectangle will be
drawn into.</P
><P
>The rectangle pointed to by <TT
CLASS="PARAMETER"
><I
>rect</I
></TT
> will be
clipped to the edges of the surface so that the clip rectangle for a
surface can never fall outside the edges of the surface.</P
><P
>If <TT
CLASS="PARAMETER"
><I
>rect</I
></TT
> is <TT
CLASS="LITERAL"
>NULL</TT
> the clipping
rectangle will be set to the full size of the surface.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN2217"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlgetcliprect.html"
><TT
CLASS="FUNCTION"
>SDL_GetClipRect</TT
></A
>,
<A
HREF="sdlblitsurface.html"
><TT
CLASS="FUNCTION"
>SDL_BlitSurface</TT
></A
>,
<A
HREF="sdlsurface.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_Surface</SPAN
></A
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