Bug 624913 - Disallow drag-and-drop within the same attachment bar

Adds a boolean "dragging" property to the EAttachmentView interface,
which becomes TRUE when the user start a drag from the attachment view.
e_attachment_view_drag_motion() and e_attachment_view_drag_drop() both
return FALSE when this property is set.

Also, do not register the entire EMsgComposer window as a drag
destination.  Just intercept drag signals from the GtkHTML widget.

Requires gtkhtml commit 344eb5e to fully work correctly.

5 files changed, 107 insertions, 8 deletions

diff --git a/widgets/misc/e-attachment-icon-view.c b/widgets/misc/e-attachment-icon-view.c
index 57301213dd..35b5d1ed18 100644
--- a/widgets/misc/e-attachment-icon-view.c
+++ b/widgets/misc/e-attachment-icon-view.c
@@ -37,6 +37,7 @@ struct _EAttachmentIconViewPrivate {
 
 enum {
 	PROP_0,
+	PROP_DRAGGING,
 	PROP_EDITABLE
 };
 
@@ -56,6 +57,12 @@ attachment_icon_view_set_property (GObject *object,
                                    GParamSpec *pspec)
 {
 	switch (property_id) {
+		case PROP_DRAGGING:
+			e_attachment_view_set_dragging (
+				E_ATTACHMENT_VIEW (object),
+				g_value_get_boolean (value));
+			return;
+
 		case PROP_EDITABLE:
 			e_attachment_view_set_editable (
 				E_ATTACHMENT_VIEW (object),
@@ -73,6 +80,12 @@ attachment_icon_view_get_property (GObject *object,
                                    GParamSpec *pspec)
 {
 	switch (property_id) {
+		case PROP_DRAGGING:
+			g_value_set_boolean (
+				value, e_attachment_view_get_dragging (
+				E_ATTACHMENT_VIEW (object)));
+			return;
+
 		case PROP_EDITABLE:
 			g_value_set_boolean (
 				value, e_attachment_view_get_editable (
@@ -436,6 +449,9 @@ attachment_icon_view_class_init (EAttachmentIconViewClass *class)
 	icon_view_class->item_activated = attachment_icon_view_item_activated;
 
 	g_object_class_override_property (
+		object_class, PROP_DRAGGING, "dragging");
+
+	g_object_class_override_property (
 		object_class, PROP_EDITABLE, "editable");
 }
 
diff --git a/widgets/misc/e-attachment-paned.c b/widgets/misc/e-attachment-paned.c
index 83a00692d8..64d97ab81f 100644
--- a/widgets/misc/e-attachment-paned.c
+++ b/widgets/misc/e-attachment-paned.c
@@ -60,6 +60,7 @@ struct _EAttachmentPanedPrivate {
 enum {
 	PROP_0,
 	PROP_ACTIVE_VIEW,
+	PROP_DRAGGING,
 	PROP_EDITABLE,
 	PROP_EXPANDED
 };
@@ -150,6 +151,12 @@ attachment_paned_set_property (GObject *object,
 				g_value_get_int (value));
 			return;
 
+		case PROP_DRAGGING:
+			e_attachment_view_set_dragging (
+				E_ATTACHMENT_VIEW (object),
+				g_value_get_boolean (value));
+			return;
+
 		case PROP_EDITABLE:
 			e_attachment_view_set_editable (
 				E_ATTACHMENT_VIEW (object),
@@ -179,6 +186,12 @@ attachment_paned_get_property (GObject *object,
 				E_ATTACHMENT_PANED (object)));
 			return;
 
+		case PROP_DRAGGING:
+			g_value_set_boolean (
+				value, e_attachment_view_get_dragging (
+				E_ATTACHMENT_VIEW (object)));
+			return;
+
 		case PROP_EDITABLE:
 			g_value_set_boolean (
 				value, e_attachment_view_get_editable (
@@ -278,6 +291,14 @@ attachment_paned_constructed (GObject *object)
 		priv->notebook, "page");
 
 	e_mutual_binding_new (
+		object, "dragging",
+		priv->icon_view, "dragging");
+
+	e_mutual_binding_new (
+		object, "dragging",
+		priv->tree_view, "dragging");
+
+	e_mutual_binding_new (
 		object, "editable",
 		priv->icon_view, "editable");
 
@@ -457,6 +478,9 @@ attachment_paned_class_init (EAttachmentPanedClass *class)
 			G_PARAM_CONSTRUCT));
 
 	g_object_class_override_property (
+		object_class, PROP_DRAGGING, "dragging");
+
+	g_object_class_override_property (
 		object_class, PROP_EDITABLE, "editable");
 }
 
diff --git a/widgets/misc/e-attachment-tree-view.c b/widgets/misc/e-attachment-tree-view.c
index 09602ca186..8e597adebb 100644
--- a/widgets/misc/e-attachment-tree-view.c
+++ b/widgets/misc/e-attachment-tree-view.c
@@ -37,6 +37,7 @@ struct _EAttachmentTreeViewPrivate {
 
 enum {
 	PROP_0,
+	PROP_DRAGGING,
 	PROP_EDITABLE
 };
 
@@ -49,6 +50,12 @@ attachment_tree_view_set_property (GObject *object,
                                    GParamSpec *pspec)
 {
 	switch (property_id) {
+		case PROP_DRAGGING:
+			e_attachment_view_set_dragging (
+				E_ATTACHMENT_VIEW (object),
+				g_value_get_boolean (value));
+			return;
+
 		case PROP_EDITABLE:
 			e_attachment_view_set_editable (
 				E_ATTACHMENT_VIEW (object),
@@ -66,6 +73,12 @@ attachment_tree_view_get_property (GObject *object,
                                    GParamSpec *pspec)
 {
 	switch (property_id) {
+		case PROP_DRAGGING:
+			g_value_set_boolean (
+				value, e_attachment_view_get_dragging (
+				E_ATTACHMENT_VIEW (object)));
+			return;
+
 		case PROP_EDITABLE:
 			g_value_set_boolean (
 				value, e_attachment_view_get_editable (
@@ -468,6 +481,9 @@ attachment_tree_view_class_init (EAttachmentTreeViewClass *class)
 	tree_view_class->row_activated = attachment_tree_view_row_activated;
 
 	g_object_class_override_property (
+		object_class, PROP_DRAGGING, "dragging");
+
+	g_object_class_override_property (
 		object_class, PROP_EDITABLE, "editable");
 }
 
diff --git a/widgets/misc/e-attachment-view.c b/widgets/misc/e-attachment-view.c
index 60ce09860d..cc587bf80b 100644
--- a/widgets/misc/e-attachment-view.c
+++ b/widgets/misc/e-attachment-view.c
@@ -824,6 +824,15 @@ attachment_view_class_init (EAttachmentViewIface *iface)
 	g_object_interface_install_property (
 		iface,
 		g_param_spec_boolean (
+			"dragging",
+			"Dragging",
+			NULL,
+			FALSE,
+			G_PARAM_READWRITE));
+
+	g_object_interface_install_property (
+		iface,
+		g_param_spec_boolean (
 			"editable",
 			"Editable",
 			NULL,
@@ -1025,6 +1034,7 @@ e_attachment_view_set_editable (EAttachmentView *view,
 	g_return_if_fail (E_IS_ATTACHMENT_VIEW (view));
 
 	priv = e_attachment_view_get_private (view);
+
 	priv->editable = editable;
 
 	if (editable)
@@ -1035,6 +1045,33 @@ e_attachment_view_set_editable (EAttachmentView *view,
 	g_object_notify (G_OBJECT (view), "editable");
 }
 
+gboolean
+e_attachment_view_get_dragging (EAttachmentView *view)
+{
+	EAttachmentViewPrivate *priv;
+
+	g_return_val_if_fail (E_IS_ATTACHMENT_VIEW (view), FALSE);
+
+	priv = e_attachment_view_get_private (view);
+
+	return priv->dragging;
+}
+
+void
+e_attachment_view_set_dragging (EAttachmentView *view,
+                                gboolean dragging)
+{
+	EAttachmentViewPrivate *priv;
+
+	g_return_if_fail (E_IS_ATTACHMENT_VIEW (view));
+
+	priv = e_attachment_view_get_private (view);
+
+	priv->dragging = dragging;
+
+	g_object_notify (G_OBJECT (view), "dragging");
+}
+
 GtkTargetList *
 e_attachment_view_get_target_list (EAttachmentView *view)
 {
@@ -1507,10 +1544,7 @@ e_attachment_view_drag_begin (EAttachmentView *view,
 
 	priv = e_attachment_view_get_private (view);
 
-	/* Prevent the user from dragging and dropping to
-	 * the same attachment view, which would duplicate
-	 * the attachment. */
-	e_attachment_view_drag_dest_unset (view);
+	e_attachment_view_set_dragging (view, TRUE);
 
 	g_warn_if_fail (priv->selected == NULL);
 	priv->selected = e_attachment_view_get_selected_attachments (view);
@@ -1569,9 +1603,7 @@ e_attachment_view_drag_end (EAttachmentView *view,
 
 	priv = e_attachment_view_get_private (view);
 
-	/* Restore the previous drag destination state. */
-	if (e_attachment_view_get_editable (view))
-		e_attachment_view_drag_dest_set (view);
+	e_attachment_view_set_dragging (view, FALSE);
 
 	g_list_foreach (priv->selected, (GFunc) g_object_unref, NULL);
 	g_list_free (priv->selected);
@@ -1698,6 +1730,11 @@ e_attachment_view_drag_motion (EAttachmentView *view,
 	if (!e_attachment_view_get_editable (view))
 		return FALSE;
 
+	/* Disallow drops if we initiated the drag.
+	 * This helps prevent duplicate attachments. */
+	if (e_attachment_view_get_dragging (view))
+		return FALSE;
+
 	actions = gdk_drag_context_get_actions (context);
 	actions &= priv->drag_actions;
 	chosen_action = gdk_drag_context_get_suggested_action (context);
@@ -1725,7 +1762,9 @@ e_attachment_view_drag_drop (EAttachmentView *view,
 	g_return_val_if_fail (E_IS_ATTACHMENT_VIEW (view), FALSE);
 	g_return_val_if_fail (GDK_IS_DRAG_CONTEXT (context), FALSE);
 
-	return TRUE;
+	/* Disallow drops if we initiated the drag.
+	 * This helps prevent duplicate attachments. */
+	return !e_attachment_view_get_dragging (view);
 }
 
 void
diff --git a/widgets/misc/e-attachment-view.h b/widgets/misc/e-attachment-view.h
index 071de0705a..79dbacb151 100644
--- a/widgets/misc/e-attachment-view.h
+++ b/widgets/misc/e-attachment-view.h
@@ -109,6 +109,7 @@ struct _EAttachmentViewPrivate {
 	gint start_x;
 	gint start_y;
 
+	guint dragging : 1;
 	guint editable : 1;
 };
 
@@ -122,6 +123,9 @@ EAttachmentViewPrivate *
 		e_attachment_view_get_private	(EAttachmentView *view);
 EAttachmentStore *
 		e_attachment_view_get_store	(EAttachmentView *view);
+gboolean	e_attachment_view_get_dragging	(EAttachmentView *view);
+void		e_attachment_view_set_dragging	(EAttachmentView *view,
+						 gboolean dragging);
 gboolean	e_attachment_view_get_editable	(EAttachmentView *view);
 void		e_attachment_view_set_editable	(EAttachmentView *view,
 						 gboolean editable);