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Date: Fri, 13 Feb 2004 17:03:16 +0100 From: Max Horn Subject: Modifier key fix The internal modifier state can get out of sync with reality. To trigger this, do for example this: 1) Launch an SDL app 2) Alt-click on the desktop (this will hide the SDL app). 3) Bring the SDL app back to the front 4) SDL will still think alt is pressed (and as such will treat left clicks like middle clicks). If you press and release alt, it'll be fine again. The attached patch cures this by rechecking the modifier state whenever we process an event.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 13 Feb 2004 17:57:16 +0000
parents 355632dca928
children
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<HTML
><HEAD
><TITLE
>SDL_SemWaitTimeout</TITLE
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><H1
><A
NAME="SDLSEMWAITTIMEOUT"
></A
>SDL_SemWaitTimeout</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN8120"
></A
><H2
>Name</H2
>SDL_SemWaitTimeout&nbsp;--&nbsp;Lock a semaphore, but only wait up to a specified maximum time.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN8123"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN8124"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"
#include "SDL_thread.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_SemWaitTimeout</B
></CODE
>(SDL_sem *sem, Uint32 timeout);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8130"
></A
><H2
>Description</H2
><P
><TT
CLASS="FUNCTION"
>SDL_SemWaitTimeout()</TT
> is a varient of
<A
HREF="sdlsemwait.html"
>SDL_SemWait</A
>
with a maximum timeout value.
If the value of the semaphore pointed to by <TT
CLASS="PARAMETER"
><I
>sem</I
></TT
> is
positive (greater than zero) it will atomically decrement the semaphore value
and return 0, otherwise it will wait up to <TT
CLASS="PARAMETER"
><I
>timeout</I
></TT
>
milliseconds trying to lock the semaphore. This function is to be avoided if
possible since on some platforms it is implemented by polling the semaphore
every millisecond in a busy loop.</P
><P
>After <TT
CLASS="FUNCTION"
>SDL_SemWaitTimeout()</TT
> is successful, the semaphore
can be released and its count atomically incremented by a successful call to
<A
HREF="sdlsempost.html"
>SDL_SemPost</A
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8140"
></A
><H2
>Return Value</H2
><P
>Returns <SPAN
CLASS="RETURNVALUE"
>0</SPAN
> if the semaphore was successfully locked or
either <SPAN
CLASS="RETURNVALUE"
>SDL_MUTEX_TIMEDOUT</SPAN
> or <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
>
if the timeout period was exceeded or there was an error, respectivly.</P
><P
>If the semaphore was not successfully locked, the semaphore will be unchanged.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8147"
></A
><H2
>Examples</H2
><P
><PRE
CLASS="PROGRAMLISTING"
>res = SDL_SemWaitTimeout(my_sem, WAIT_TIMEOUT_MILLISEC);

if (res == SDL_MUTEX_TIMEDOUT) {
        return TRY_AGAIN;
}
if (res == -1) {
        return WAIT_ERROR;
}

...

SDL_SemPost(my_sem);</PRE
></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN8151"
></A
><H2
>See Also</H2
><P
><A
HREF="sdlcreatesemaphore.html"
><TT
CLASS="FUNCTION"
>SDL_CreateSemaphore</TT
></A
>,
<A
HREF="sdldestroysemaphore.html"
><TT
CLASS="FUNCTION"
>SDL_DestroySemaphore</TT
></A
>,
<A
HREF="sdlsemwait.html"
><TT
CLASS="FUNCTION"
>SDL_SemWait</TT
></A
>,
<A
HREF="sdlsemtrywait.html"
><TT
CLASS="FUNCTION"
>SDL_SemTryWait</TT
></A
>,
<A
HREF="sdlsempost.html"
><TT
CLASS="FUNCTION"
>SDL_SemPost</TT
></A
>,
<A
HREF="sdlsemvalue.html"
><TT
CLASS="FUNCTION"
>SDL_SemValue</TT
></A
></P
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