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 <stdio.h>
  30 #include <GP.h>
  31
  32 static void redraw(GP_Backend *self)
  33 {
  34         GP_Context *context = self->context;
  35         GP_Pixel black_pixel = GP_RGBToContextPixel(0x00, 0x00, 0x00, context);
  36
  37         GP_Fill(context, black_pixel);
  38
  39         /* Update the backend screen */
  40         GP_BackendFlip(self);
  41 }
  42
  43 static uint32_t timer_callback(GP_Timer *self)
  44 {
  45         uint32_t next = random() % 10000;
  46
  47         printf("Timer %s callback called, rescheduling after %u.\n",
  48                self->id, (unsigned) next);
  49
  50         return next;
  51 }
  52
  53 int main(void)
  54 {
  55         GP_Backend *backend;
  56         const char *backend_opts = "X11:100x100";
  57
  58         backend = GP_BackendInit(backend_opts, "Backend Timers Example");
  59
  60         if (backend == NULL) {
  61                 fprintf(stderr, "Failed to initialize backend\n");
  62                 return 1;
  63         }
  64
  65         redraw(backend);
  66
  67         /*
  68          * Periodic timer with 1000ms interval. As the callback is set to NULL
  69          * Timer Event is pushed to event queue upon expiration.
  70          */
  71         GP_TIMER_DECLARE(timer1, 0, 1000, "Timer 1", NULL, NULL);
  72
  73         /*
  74          * Timer with a callback, this timer gets scheduled depending on ouput
  75          * from callback (0 means disable timer).
  76          */
  77         GP_TIMER_DECLARE(timer2, 5000, 0, "Timer 2", timer_callback, NULL);
  78
  79         GP_BackendAddTimer(backend, &timer1);
  80         GP_BackendAddTimer(backend, &timer2);
  81
  82         /* Handle events */
  83         for (;;) {
  84                 GP_Event ev;
  85
  86                 GP_BackendWaitEvent(backend, &ev);
  87
  88                 GP_EventDump(&ev);
  89
  90                 switch (ev.type) {
  91                 case GP_EV_KEY:
  92                         switch (ev.val.val) {
  93                         case GP_KEY_ESC:
  94                         case GP_KEY_Q:
  95                                 GP_BackendExit(backend);
  96                                 return 0;
  97                         break;
  98                         }
  99                 break;
 100                 case GP_EV_SYS:
 101                         switch (ev.code) {
 102                         case GP_EV_SYS_RESIZE:
 103                                 GP_BackendResizeAck(backend);
 104                                 redraw(backend);
 105                         break;
 106                         case GP_EV_SYS_QUIT:
 107                                 GP_BackendExit(backend);
 108                                 return 0;
 109                         break;
 110                         }
 111                 break;
 112                 }
 113         }
 114
 115         GP_BackendExit(backend);
 116
 117         return 0;
 118 }