demos/c_simple/backend_timers_example.c

   1 /*****************************************************************************
   2  * This file is part of gfxprim library.                                     *
   3  *                                                                           *
   4  * Gfxprim is free software; you can redistribute it and/or                  *
   5  * modify it under the terms of the GNU Lesser General Public                *
   6  * License as published by the Free Software Foundation; either              *
   7  * version 2.1 of the License, or (at your option) any later version.        *
   8  *                                                                           *
   9  * Gfxprim is distributed in the hope that it will be useful,                *
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of            *
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU         *
  12  * Lesser General Public License for more details.                           *
  13  *                                                                           *
  14  * You should have received a copy of the GNU Lesser General Public          *
  15  * License along with gfxprim; if not, write to the Free Software            *
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,                        *
  17  * Boston, MA  02110-1301  USA                                               *
  18  *                                                                           *
  19  * Copyright (C) 2009-2013 Cyril Hrubis <metan@ucw.cz>                       *
  20  *                                                                           *
  21  *****************************************************************************/
  22
  23  /*
  24
  25    Simple backend timers example.
  26
  27   */
  28
  29 #include <GP.h>
  30
  31 static void redraw(GP_Backend *self)
  32 {
  33         GP_Context *context = self->context;
  34         GP_Pixel black_pixel = GP_ColorToContextPixel(GP_COL_BLACK, context);
  35
  36         GP_Fill(context, black_pixel);
  37
  38         /* Update the backend screen */
  39         GP_BackendFlip(self);
  40 }
  41
  42 static uint32_t timer_callback(GP_Timer *self)
  43 {
  44         uint32_t next = random() % 10000;
  45
  46         printf("Timer %s callback called, rescheduling after %u.\n",
  47                self->id, (unsigned) next);
  48
  49         return next;
  50 }
  51
  52 int main(void)
  53 {
  54         GP_Backend *backend;
  55         const char *backend_opts = "X11:100x100";
  56
  57         backend = GP_BackendInit(backend_opts, "Backend Timers Example");
  58
  59         if (backend == NULL) {
  60                 fprintf(stderr, "Failed to initialize backend\n");
  61                 return 1;
  62         }
  63
  64         redraw(backend);
  65
  66         /*
  67          * Periodic timer with 1000ms interval. As the callback is set to NULL
  68          * Timer Event is pushed to event queue upon expiration.
  69          */
  70         GP_TIMER_DECLARE(timer1, 0, 1000, "Timer 1", NULL, NULL);
  71
  72         /*
  73          * Timer with a callback, this timer gets scheduled depending on ouput
  74          * from callback (0 means disable timer).
  75          */
  76         GP_TIMER_DECLARE(timer2, 5000, 0, "Timer 2", timer_callback, NULL);
  77
  78         GP_BackendAddTimer(backend, &timer1);
  79         GP_BackendAddTimer(backend, &timer2);
  80
  81         /* Handle events */
  82         for (;;) {
  83                 GP_Event ev;
  84
  85                 GP_BackendWaitEvent(backend, &ev);
  86
  87                 GP_EventDump(&ev);
  88
  89                 switch (ev.type) {
  90                 case GP_EV_KEY:
  91                         switch (ev.val.val) {
  92                         case GP_KEY_ESC:
  93                         case GP_KEY_Q:
  94                                 GP_BackendExit(backend);
  95                                 return 0;
  96                         break;
  97                         }
  98                 break;
  99                 case GP_EV_SYS:
 100                         switch (ev.code) {
 101                         case GP_EV_SYS_RESIZE:
 102                                 GP_BackendResizeAck(backend);
 103                                 redraw(backend);
 104                         break;
 105                         case GP_EV_SYS_QUIT:
 106                                 GP_BackendExit(backend);
 107                                 return 0;
 108                         break;
 109                         }
 110                 break;
 111                 }
 112         }
 113
 114         GP_BackendExit(backend);
 115
 116         return 0;
 117 }