Update all of the examples to use cogl_poll_get_info

The aim is that it should be a requirement that all Cogl applications
hook their mainloops into Cogl so we should lead by examples. Most of
the examples now just call cogl_poll_get_info and then g_poll with a
zero timeout so that they can continue to constantly redraw.

The SDL example is a bit special because SDL makes it very difficult
to wait on either a timeout or any file descriptors. The SDL winsys is
documented not to require blocking on any file descriptors so we can
ignore that. It implements the timeout by adding an SDL timer which
pushes an event to the queue to wake up SDL_GetEvent.

The Cogland example was already using the glib main loop so that one
has been updated to add the CoglGLibSource to it.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

examples/cogl-crate.c

@@ -272,8 +272,16 @@ main (int argc, char **argv)
 
   while (1)
     {
+      CoglPollFD *poll_fds;
+      int n_poll_fds;
+      gint64 timeout;
+
       paint (&data);
       cogl_framebuffer_swap_buffers (fb);
+
+      cogl_poll_get_info (ctx, &poll_fds, &n_poll_fds, &timeout);
+      g_poll ((GPollFD *) poll_fds, n_poll_fds, 0);
+      cogl_poll_dispatch (ctx, poll_fds, n_poll_fds);
     }
 
   return 0;

examples/cogl-hello.c

@@ -40,9 +40,17 @@ main (int argc, char **argv)
     triangle = cogl_primitive_new_p2c4 (COGL_VERTICES_MODE_TRIANGLES,
                                         3, triangle_vertices);
     for (;;) {
+        CoglPollFD *poll_fds;
+        int n_poll_fds;
+        gint64 timeout;
+
         cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
         cogl_primitive_draw (triangle);
         cogl_framebuffer_swap_buffers (fb);
+
+        cogl_poll_get_info (ctx, &poll_fds, &n_poll_fds, &timeout);
+        g_poll ((GPollFD *) poll_fds, n_poll_fds, 0);
+        cogl_poll_dispatch (ctx, poll_fds, n_poll_fds);
     }
 
     return 0;

examples/cogl-msaa.c

@@ -88,6 +88,10 @@ main (int argc, char **argv)
     pipeline = cogl_pipeline_new ();
 
     for (;;) {
+        CoglPollFD *poll_fds;
+        int n_poll_fds;
+        gint64 timeout;
+
         cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
 
         cogl_push_matrix ();
@@ -106,6 +110,10 @@ main (int argc, char **argv)
         cogl_rectangle (0, 1, 1, -1);
 
         cogl_framebuffer_swap_buffers (fb);
+
+        cogl_poll_get_info (ctx, &poll_fds, &n_poll_fds, &timeout);
+        g_poll ((GPollFD *) poll_fds, n_poll_fds, 0);
+        cogl_poll_dispatch (ctx, poll_fds, n_poll_fds);
     }
 
     return 0;

examples/cogl-sdl-hello.c

@@ -12,6 +12,7 @@ typedef struct Data
   CoglPrimitive *triangle;
   float center_x, center_y;
   CoglFramebuffer *fb;
+  gboolean quit;
 } Data;
 
 static void
@@ -28,6 +29,85 @@ redraw (Data *data)
   cogl_framebuffer_swap_buffers (data->fb);
 }
 
+static void
+handle_event (Data *data, SDL_Event *event)
+{
+  switch (event->type)
+    {
+    case SDL_VIDEOEXPOSE:
+      redraw (data);
+      break;
+
+    case SDL_MOUSEMOTION:
+      {
+        int width =
+          cogl_framebuffer_get_width (COGL_FRAMEBUFFER (data->fb));
+        int height =
+          cogl_framebuffer_get_height (COGL_FRAMEBUFFER (data->fb));
+
+        data->center_x = event->motion.x * 2.0f / width - 1.0f;
+        data->center_y = event->motion.y * 2.0f / height - 1.0f;
+
+        redraw (data);
+      }
+      break;
+
+    case SDL_QUIT:
+      data->quit = TRUE;
+      break;
+    }
+}
+
+static Uint32
+timer_handler (Uint32 interval, void *user_data)
+{
+  static const SDL_UserEvent dummy_event =
+    {
+      SDL_USEREVENT
+    };
+
+  /* Post an event to wake up from SDL_WaitEvent */
+  SDL_PushEvent ((SDL_Event *) &dummy_event);
+
+  return 0;
+}
+
+static gboolean
+wait_event_with_timeout (Data *data, SDL_Event *event, gint64 timeout)
+{
+  if (timeout == -1)
+    {
+      if (SDL_WaitEvent (event))
+        return TRUE;
+      else
+        {
+          data->quit = TRUE;
+          return FALSE;
+        }
+    }
+  else if (timeout == 0)
+    return SDL_PollEvent (event);
+  else
+    {
+      gboolean ret;
+      /* Add a timer so that we can wake up the event loop */
+      SDL_TimerID timer_id =
+        SDL_AddTimer (timeout / 1000, timer_handler, data);
+
+      if (SDL_WaitEvent (event))
+        ret = TRUE;
+      else
+        {
+          data->quit = TRUE;
+          ret = FALSE;
+        }
+
+      SDL_RemoveTimer (timer_id);
+
+      return ret;
+    }
+}
+
 int
 main (int argc, char **argv)
 {
@@ -55,6 +135,8 @@ main (int argc, char **argv)
       return 1;
     }
 
+  SDL_InitSubSystem (SDL_INIT_TIMER);
+
   onscreen = cogl_onscreen_new (ctx, 800, 600);
   /* Eventually there will be an implicit allocate on first use so this
    * will become optional... */
@@ -69,6 +151,7 @@ main (int argc, char **argv)
   cogl_color_set_from_4ub (&data.black, 0, 0, 0, 255);
   data.center_x = 0.0f;
   data.center_y = 0.0f;
+  data.quit = FALSE;
 
   cogl_onscreen_show (onscreen);
 
@@ -76,37 +159,27 @@ main (int argc, char **argv)
 
   data.triangle = cogl_primitive_new_p2c4 (COGL_VERTICES_MODE_TRIANGLES,
                                            3, triangle_vertices);
-  while (SDL_WaitEvent (&event))
+  while (!data.quit)
     {
-      switch (event.type)
-        {
-        case SDL_VIDEOEXPOSE:
-          redraw (&data);
-          break;
+      CoglPollFD *poll_fds;
+      int n_poll_fds;
+      gint64 timeout;
 
-        case SDL_MOUSEMOTION:
-          {
-            int width =
-              cogl_framebuffer_get_width (COGL_FRAMEBUFFER (data.fb));
-            int height =
-              cogl_framebuffer_get_height (COGL_FRAMEBUFFER (data.fb));
+      cogl_poll_get_info (ctx, &poll_fds, &n_poll_fds, &timeout);
 
-            data.center_x = event.motion.x * 2.0f / width - 1.0f;
-            data.center_y = event.motion.y * 2.0f / height - 1.0f;
+      /* It's difficult to wait for file descriptors using the SDL
+         event mechanism, but it the SDL winsys is documented that it
+         will never require this so we can assert that there are no
+         fds */
+      g_assert (n_poll_fds == 0);
 
-            redraw (&data);
+      if (wait_event_with_timeout (&data, &event, timeout))
+        do
+          handle_event (&data, &event);
+        while (SDL_PollEvent (&event));
+
+      cogl_poll_dispatch (ctx, poll_fds, n_poll_fds);
     }
-          break;
-
-        case SDL_QUIT:
-          goto done;
-        }
-    }
-
-  fprintf (stderr, "Error waiting for an event: %s\n",
-           SDL_GetError ());
-
- done:
 
   cogl_pop_framebuffer ();
 

examples/cogl-x11-foreign.c

@@ -163,6 +163,10 @@ main (int argc, char **argv)
                                       3, triangle_vertices);
   for (;;)
     {
+      CoglPollFD *poll_fds;
+      int n_poll_fds;
+      gint64 timeout;
+
       while (XPending (xdpy))
         {
           XEvent event;
@@ -178,6 +182,10 @@ main (int argc, char **argv)
       cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
       cogl_primitive_draw (triangle);
       cogl_framebuffer_swap_buffers (fb);
+
+      cogl_poll_get_info (ctx, &poll_fds, &n_poll_fds, &timeout);
+      g_poll ((GPollFD *) poll_fds, n_poll_fds, 0);
+      cogl_poll_dispatch (ctx, poll_fds, n_poll_fds);
     }
 
   return 0;

examples/cogland.c

@@ -705,6 +705,7 @@ main (int argc, char **argv)
       {-0.7, -0.7, 0x00, 0xff, 0x00, 0xff},
       {0.7, -0.7, 0x00, 0x00, 0xff, 0xff}
   };
+  GSource *cogl_source;
 
   memset (&compositor, 0, sizeof (compositor));
 
@@ -761,6 +762,11 @@ main (int argc, char **argv)
 
   g_timeout_add (16, paint_cb, &compositor);
 
+  cogl_source = cogl_glib_source_new (compositor.cogl_context,
+                                      G_PRIORITY_DEFAULT);
+
+  g_source_attach (cogl_source, NULL);
+
   g_main_loop_run (loop);
 
   return 0;