Mercurial > sdl-ios-xcode
view docs/html/sdlpollevent.html @ 765:4c2ba6161939
Editors Note: The original patch was modified to use SDL_Delay() instead of
nanosleep because nanosleep may not be portable to all systems
using SDL with the ALSA backend. This may be a moot point with
the switch to blocking writes anyway...
Date: Sat, 27 Dec 2003 21:47:36 +0100
From: Michel Daenzer
To: Debian Bug Tracking System
Subject: [SDL] Bug#225252: [PATCH] ALSA fixes
Package: libsdl1.2debian-all
Version: 1.2.6-2
Severity: normal
Tags: patch
For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with
SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU
usage, interrupted sound and stuttering in some games here. Taking a nanosleep
whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more
efficient to use blocking mode for the actual sound playback. Feedback from the
SDL and ALSA lists appreciated.
The patch also fixes the default ALSA device to be used.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Sun, 04 Jan 2004 15:40:50 +0000 |
parents | e5bc29de3f0a |
children | 355632dca928 |
line wrap: on
line source
<HTML ><HEAD ><TITLE >SDL_PollEvent</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="Event Functions." HREF="eventfunctions.html"><LINK REL="PREVIOUS" TITLE="SDL_PeepEvents" HREF="sdlpeepevents.html"><LINK REL="NEXT" TITLE="SDL_WaitEvent" HREF="sdlwaitevent.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="sdlpeepevents.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="sdlwaitevent.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SDLPOLLEVENT" >SDL_PollEvent</A ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN5084" ></A ><H2 >Name</H2 >SDL_PollEvent -- Polls for currently pending events.</DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN5087" ></A ><H2 >Synopsis</H2 ><DIV CLASS="FUNCSYNOPSIS" ><A NAME="AEN5088" ></A ><P ></P ><PRE CLASS="FUNCSYNOPSISINFO" >#include "SDL.h"</PRE ><P ><CODE ><CODE CLASS="FUNCDEF" >int <B CLASS="FSFUNC" >SDL_PollEvent</B ></CODE >(SDL_Event *event);</CODE ></P ><P ></P ></DIV ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN5094" ></A ><H2 >Description</H2 ><P >Polls for currently pending events, and returns <SPAN CLASS="RETURNVALUE" >1</SPAN > if there are any pending events, or <SPAN CLASS="RETURNVALUE" >0</SPAN > if there are none available. </P ><P >If <TT CLASS="PARAMETER" ><I >event</I ></TT > is not <TT CLASS="LITERAL" >NULL</TT >, the next event is removed from the queue and stored in that area.</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN5102" ></A ><H2 >Examples</H2 ><P ><PRE CLASS="PROGRAMLISTING" >SDL_Event event; /* Event structure */ . . . /* Check for events */ while(SDL_PollEvent(&event)){ /* Loop until there are no events left on the queue */ switch(event.type){ /* Process the appropiate event type */ case SDL_KEYDOWN: /* Handle a KEYDOWN event */ printf("Oh! Key press\n"); break; case SDL_MOUSEMOTION: . . . default: /* Report an unhandled event */ printf("I don't know what this event is!\n"); } }</PRE ></P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN5106" ></A ><H2 >See Also</H2 ><P ><A HREF="sdlevent.html" ><SPAN CLASS="STRUCTNAME" >SDL_Event</SPAN ></A >, <A HREF="sdlwaitevent.html" ><TT CLASS="FUNCTION" >SDL_WaitEvent</TT ></A >, <A HREF="sdlpeepevents.html" ><TT CLASS="FUNCTION" >SDL_PeepEvents</TT ></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="sdlpeepevents.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="sdlwaitevent.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SDL_PeepEvents</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="eventfunctions.html" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SDL_WaitEvent</TD ></TR ></TABLE ></DIV ></BODY ></HTML >