[gedit: 2/2] tab: improve timer handling for showing progress info bar

[Sébastien Wilmet <swilmet src gnome org>]

commit f13e9b6b14cc5c0de539caf96b965cb8f5f3fde1
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Tue Apr 28 16:13:59 2015 +0200

    tab: improve timer handling for showing progress info bar
    
    - Start the timer before launching the operation.
    - Wait 0.5 seconds before showing the progress info.

 gedit/gedit-tab.c |  107 ++++++++++++++++++++++++++++++++--------------------
 1 files changed, 66 insertions(+), 41 deletions(-)
---
diff --git a/gedit/gedit-tab.c b/gedit/gedit-tab.c
index a6232fd..2a9c451 100644
--- a/gedit/gedit-tab.c
+++ b/gedit/gedit-tab.c
@@ -951,6 +951,53 @@ info_bar_set_progress (GeditTab *tab,
        }
 }
 
+/* Returns whether progress info should be shown. */
+static gboolean
+should_show_progress_info (GeditTab *tab,
+                          goffset   size,
+                          goffset   total_size)
+{
+       gdouble elapsed_time;
+       gdouble total_time;
+       gdouble remaining_time;
+
+       if (tab->timer == NULL)
+       {
+               return TRUE;
+       }
+
+       elapsed_time = g_timer_elapsed (tab->timer, NULL);
+
+       /* Wait a little, because at the very beginning it's maybe not very
+        * accurate (it takes initially more time for the first bytes, the
+        * following chunks should arrive more quickly, as a rough guess).
+        */
+       if (elapsed_time < 0.5)
+       {
+               return FALSE;
+       }
+
+       /* elapsed_time / total_time = size / total_size */
+       total_time = (elapsed_time * total_size) / size;
+
+       remaining_time = total_time - elapsed_time;
+
+       /* Approximately more than 3 seconds remaining. */
+       if (remaining_time > 3.0)
+       {
+               /* Once the progress info bar is shown, it must remain
+                * shown until the end, so we don't need the timer
+                * anymore.
+                */
+               g_timer_destroy (tab->timer);
+               tab->timer = NULL;
+
+               return TRUE;
+       }
+
+       return FALSE;
+}
+
 static gboolean
 scroll_to_cursor (GeditTab *tab)
 {
@@ -1646,32 +1693,14 @@ loader_progress_cb (goffset   size,
                    goffset   total_size,
                    GeditTab *tab)
 {
-       gdouble elapsed_time;
-       gdouble total_time;
-       gdouble remaining_time;
-
        g_return_if_fail (tab->state == GEDIT_TAB_STATE_LOADING ||
-                         tab->state == GEDIT_TAB_STATE_REVERTING);
-
-       if (tab->timer == NULL)
-       {
-               tab->timer = g_timer_new ();
-       }
-
-       elapsed_time = g_timer_elapsed (tab->timer, NULL);
+                         tab->state == GEDIT_TAB_STATE_REVERTING);
 
-       /* elapsed_time / total_time = size / total_size */
-       total_time = (elapsed_time * total_size) / size;
-
-       remaining_time = total_time - elapsed_time;
-
-       /* Approximately more than 3 seconds remaining. */
-       if (remaining_time > 3.0)
+       if (should_show_progress_info (tab, size, total_size))
        {
                show_loading_info_bar (tab);
+               info_bar_set_progress (tab, size, total_size);
        }
-
-       info_bar_set_progress (tab, size, total_size);
 }
 
 static void
@@ -2028,6 +2057,13 @@ load (GeditTab                *tab,
        doc = gedit_tab_get_document (tab);
        g_signal_emit_by_name (doc, "load");
 
+       if (tab->timer != NULL)
+       {
+               g_timer_destroy (tab->timer);
+       }
+
+       tab->timer = g_timer_new ();
+
        /* Keep the tab alive during the async operation. */
        g_object_ref (tab);
 
@@ -2168,31 +2204,13 @@ saver_progress_cb (goffset   size,
                   goffset   total_size,
                   GeditTab *tab)
 {
-       gdouble elapsed_time;
-       gdouble total_time;
-       gdouble remaining_time;
-
        g_return_if_fail (tab->state == GEDIT_TAB_STATE_SAVING);
 
-       if (tab->timer == NULL)
-       {
-               tab->timer = g_timer_new ();
-       }
-
-       elapsed_time = g_timer_elapsed (tab->timer, NULL);
-
-       /* elapsed_time / total_time = size / total_size */
-       total_time = (elapsed_time * total_size) / size;
-
-       remaining_time = total_time - elapsed_time;
-
-       /* Approximately more than 3 seconds remaining. */
-       if (remaining_time > 3.0)
+       if (should_show_progress_info (tab, size, total_size))
        {
                show_saving_info_bar (tab);
+               info_bar_set_progress (tab, size, total_size);
        }
-
-       info_bar_set_progress (tab, size, total_size);
 }
 
 static void
@@ -2336,6 +2354,13 @@ save (GeditTab *tab)
 
        data = g_task_get_task_data (tab->task_saver);
 
+       if (tab->timer != NULL)
+       {
+               g_timer_destroy (tab->timer);
+       }
+
+       tab->timer = g_timer_new ();
+
        gtk_source_file_saver_save_async (data->saver,
                                          G_PRIORITY_DEFAULT,
                                          g_task_get_cancellable (tab->task_saver),