Add a GCancellable to EActivity.

EActivity now uses a GCancellable to manage cancellations, instead of
having its own redundant cancellation API.  API changes are as follows:

  + e_activity_get_cancellable()
  + e_activity_set_cancellable()

  - e_activity_cancel()
  - e_activity_is_cancelled()
  - e_activity_get_allow_cancel()
  - e_activity_set_allow_cancel()

EActivity's "cancelled" signal remains, but only as a repeater for
GCancellable::cancelled signals.  It should not be emitted directly.

The presence of a GCancellable implies that cancellation is allowed.
EActivity does not create its own default GCancellable, it has to be
given one.

If a CamelOperation (cast as a GCancellable) is given, EActivity will
configure itself to listen for status updates from the CamelOperation
and propagate the information to its own "primary-text" and "percent"
properties.

These changes allowed me to start cleaning up some of the incredibly
convoluted logic in mail-mt.c -- in particular, mail_operation_status()
is completely gone now.  mail-mt.c is still in a transitional state --
much more significant changes coming soon.

1 files changed, 21 insertions, 6 deletions

diff --git a/widgets/misc/e-activity-proxy.c b/widgets/misc/e-activity-proxy.c
index 8e20e67d5d..e96f18ed63 100644
--- a/widgets/misc/e-activity-proxy.c
+++ b/widgets/misc/e-activity-proxy.c
@@ -47,19 +47,33 @@ G_DEFINE_TYPE (
 	GTK_TYPE_EVENT_BOX)
 
 static void
+activity_proxy_cancel (EActivity *activity)
+{
+	GCancellable *cancellable;
+
+	/* We shouldn't get here unless the EActivity has a GCancellable,
+	 * since otherwise the cancel button is invisible and unclickable.
+	 * g_cancellable_cancel() will emit a warning if this breaks. */
+
+	cancellable = e_activity_get_cancellable (activity);
+	g_cancellable_cancel (cancellable);
+}
+
+static void
 activity_proxy_update (EActivityProxy *proxy)
 {
-	EActivity *activity = proxy->priv->activity;
+	EActivity *activity;
+	GCancellable *cancellable;
 	const gchar *icon_name;
-	gboolean allow_cancel;
 	gboolean cancelled;
 	gboolean clickable;
 	gboolean completed;
 	gboolean sensitive;
 	gchar *description;
 
-	allow_cancel = e_activity_get_allow_cancel (activity);
-	cancelled = e_activity_is_cancelled (activity);
+	activity = proxy->priv->activity;
+	cancellable = e_activity_get_cancellable (activity);
+	cancelled = g_cancellable_is_cancelled (cancellable);
 	clickable = e_activity_get_clickable (activity);
 	completed = e_activity_is_completed (activity);
 	icon_name = e_activity_get_icon_name (activity);
@@ -67,6 +81,7 @@ activity_proxy_update (EActivityProxy *proxy)
 	description = e_activity_describe (activity);
 	gtk_widget_set_tooltip_text (GTK_WIDGET (proxy), description);
 	gtk_label_set_text (GTK_LABEL (proxy->priv->label), description);
+	gtk_widget_set_visible (GTK_WIDGET (proxy), (description != NULL));
 	g_free (description);
 
 	/* Note, an activity requires an icon name in order to
@@ -93,7 +108,7 @@ activity_proxy_update (EActivityProxy *proxy)
 		gtk_widget_hide (proxy->priv->image);
 	}
 
-	if (allow_cancel)
+	if (cancellable != NULL)
 		gtk_widget_show (proxy->priv->cancel);
 	else
 		gtk_widget_hide (proxy->priv->cancel);
@@ -202,7 +217,7 @@ activity_proxy_constructed (GObject *object)
 
 	g_signal_connect_swapped (
 		proxy->priv->cancel, "clicked",
-		G_CALLBACK (e_activity_cancel), proxy->priv->activity);
+		G_CALLBACK (activity_proxy_cancel), proxy->priv->activity);
 
 	g_signal_connect_swapped (
 		proxy->priv->activity, "cancelled",