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73 | ><H1 |
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75 | ><A |
76 | NAME="GUIDEEVENTEXAMPLES" |
77 | ></A |
78 | >Event Examples</H1 |
79 | ><P |
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82 | CLASS="SECT2" |
83 | ><H2 |
84 | CLASS="SECT2" |
85 | ><A |
86 | NAME="AEN375" |
87 | ></A |
88 | >Filtering and Handling Events</H2 |
89 | ><P |
90 | ><PRE |
91 | CLASS="PROGRAMLISTING" |
92 | >#include <stdio.h> |
93 | #include <stdlib.h> |
94 | |
95 | #include "SDL.h" |
96 | |
97 | /* This function may run in a separate event thread */ |
98 | int FilterEvents(const SDL_Event *event) { |
99 | static int boycott = 1; |
100 | |
101 | /* This quit event signals the closing of the window */ |
102 | if ( (event->type == SDL_QUIT) && boycott ) { |
103 | printf("Quit event filtered out -- try again.\n"); |
104 | boycott = 0; |
105 | return(0); |
106 | } |
107 | if ( event->type == SDL_MOUSEMOTION ) { |
108 | printf("Mouse moved to (%d,%d)\n", |
109 | event->motion.x, event->motion.y); |
110 | return(0); /* Drop it, we've handled it */ |
111 | } |
112 | return(1); |
113 | } |
114 | |
115 | int main(int argc, char *argv[]) |
116 | { |
117 | SDL_Event event; |
118 | |
119 | /* Initialize the SDL library (starts the event loop) */ |
120 | if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) { |
121 | fprintf(stderr, |
122 | "Couldn't initialize SDL: %s\n", SDL_GetError()); |
123 | exit(1); |
124 | } |
125 | |
126 | /* Clean up on exit, exit on window close and interrupt */ |
127 | atexit(SDL_Quit); |
128 | |
129 | /* Ignore key events */ |
130 | SDL_EventState(SDL_KEYDOWN, SDL_IGNORE); |
131 | SDL_EventState(SDL_KEYUP, SDL_IGNORE); |
132 | |
133 | /* Filter quit and mouse motion events */ |
134 | SDL_SetEventFilter(FilterEvents); |
135 | |
136 | /* The mouse isn't much use unless we have a display for reference */ |
137 | if ( SDL_SetVideoMode(640, 480, 8, 0) == NULL ) { |
138 | fprintf(stderr, "Couldn't set 640x480x8 video mode: %s\n", |
139 | SDL_GetError()); |
140 | exit(1); |
141 | } |
142 | |
143 | /* Loop waiting for ESC+Mouse_Button */ |
144 | while ( SDL_WaitEvent(&event) >= 0 ) { |
145 | switch (event.type) { |
146 | case SDL_ACTIVEEVENT: { |
147 | if ( event.active.state & SDL_APPACTIVE ) { |
148 | if ( event.active.gain ) { |
149 | printf("App activated\n"); |
150 | } else { |
151 | printf("App iconified\n"); |
152 | } |
153 | } |
154 | } |
155 | break; |
156 | |
157 | case SDL_MOUSEBUTTONDOWN: { |
158 | Uint8 *keys; |
159 | |
160 | keys = SDL_GetKeyState(NULL); |
161 | if ( keys[SDLK_ESCAPE] == SDL_PRESSED ) { |
162 | printf("Bye bye...\n"); |
163 | exit(0); |
164 | } |
165 | printf("Mouse button pressed\n"); |
166 | } |
167 | break; |
168 | |
169 | case SDL_QUIT: { |
170 | printf("Quit requested, quitting.\n"); |
171 | exit(0); |
172 | } |
173 | break; |
174 | } |
175 | } |
176 | /* This should never happen */ |
177 | printf("SDL_WaitEvent error: %s\n", SDL_GetError()); |
178 | exit(1); |
179 | }</PRE |
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