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<HTML><HEAD><TITLE>Event Examples</TITLE><METANAME="GENERATOR"CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+"><LINKREL="HOME"TITLE="SDL Library Documentation"HREF="index.html"><LINKREL="UP"TITLE="Examples"HREF="guideexamples.html"><LINKREL="PREVIOUS"TITLE="Examples"HREF="guideexamples.html"><LINKREL="NEXT"TITLE="Audio Examples"HREF="guideaudioexamples.html"></HEAD><BODYCLASS="SECT1"BGCOLOR="#FFF8DC"TEXT="#000000"LINK="#0000ee"VLINK="#551a8b"ALINK="#ff0000"><DIVCLASS="NAVHEADER"><TABLESUMMARY="Header navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><THCOLSPAN="3"ALIGN="center">SDL Library Documentation</TH></TR><TR><TDWIDTH="10%"ALIGN="left"VALIGN="bottom"><AHREF="guideexamples.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom">Chapter 4. Examples</TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><AHREF="guideaudioexamples.html"ACCESSKEY="N">Next</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="SECT1"><H1CLASS="SECT1"><ANAME="GUIDEEVENTEXAMPLES"></A>Event Examples</H1><P></P><DIVCLASS="SECT2"><H2CLASS="SECT2"><ANAME="AEN375"></A>Filtering and Handling Events</H2><P><PRECLASS="PROGRAMLISTING">#include <stdio.h>#include <stdlib.h>#include "SDL.h"/* This function may run in a separate event thread */int FilterEvents(const SDL_Event *event) { static int boycott = 1; /* This quit event signals the closing of the window */ if ( (event->type == SDL_QUIT) && boycott ) { printf("Quit event filtered out -- try again.\n"); boycott = 0; return(0); } if ( event->type == SDL_MOUSEMOTION ) { printf("Mouse moved to (%d,%d)\n", event->motion.x, event->motion.y); return(0); /* Drop it, we've handled it */ } return(1);}int main(int argc, char *argv[]){ SDL_Event event; /* Initialize the SDL library (starts the event loop) */ if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) { fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError()); exit(1); } /* Clean up on exit, exit on window close and interrupt */ atexit(SDL_Quit); /* Ignore key events */ SDL_EventState(SDL_KEYDOWN, SDL_IGNORE); SDL_EventState(SDL_KEYUP, SDL_IGNORE); /* Filter quit and mouse motion events */ SDL_SetEventFilter(FilterEvents); /* The mouse isn't much use unless we have a display for reference */ if ( SDL_SetVideoMode(640, 480, 8, 0) == NULL ) { fprintf(stderr, "Couldn't set 640x480x8 video mode: %s\n", SDL_GetError()); exit(1); } /* Loop waiting for ESC+Mouse_Button */ while ( SDL_WaitEvent(&event) >= 0 ) { switch (event.type) { case SDL_ACTIVEEVENT: { if ( event.active.state & SDL_APPACTIVE ) { if ( event.active.gain ) { printf("App activated\n"); } else { printf("App iconified\n"); } } } break; case SDL_MOUSEBUTTONDOWN: { Uint8 *keys; keys = SDL_GetKeyState(NULL); if ( keys[SDLK_ESCAPE] == SDL_PRESSED ) { printf("Bye bye...\n"); exit(0); } printf("Mouse button pressed\n"); } break; case SDL_QUIT: { printf("Quit requested, quitting.\n"); exit(0); } break; } } /* This should never happen */ printf("SDL_WaitEvent error: %s\n", SDL_GetError()); exit(1);}</PRE></P></DIV></DIV><DIVCLASS="NAVFOOTER"><HRALIGN="LEFT"WIDTH="100%"><TABLESUMMARY="Footer navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top"><AHREF="guideexamples.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="index.html"ACCESSKEY="H">Home</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top"><AHREF="guideaudioexamples.html"ACCESSKEY="N">Next</A></TD></TR><TR><TDWIDTH="33%"ALIGN="left"VALIGN="top">Examples</TD><TDWIDTH="34%"ALIGN="center"VALIGN="top"><AHREF="guideexamples.html"ACCESSKEY="U">Up</A></TD><TDWIDTH="33%"ALIGN="right"VALIGN="top">Audio Examples</TD></TR></TABLE></DIV></BODY></HTML>⌨️ 快捷键说明
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