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| >Filtering and Handling Events</H2 |
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| ><PRE |
| CLASS="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 |
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