[presentation] Make sure we always have a valid surface to draw a page

It avoids flickering or even a black screen when changing pages fast.
Fixes bug #602738.

diff --git a/libview/ev-view-presentation.c b/libview/ev-view-presentation.c
index 2dfed6a08616df78a2412fbd694c656b471f1ee6..c5166023fdbbadf0653b4b4f71d5d023508c80bc 100644 (file)
--- a/libview/ev-view-presentation.c
+++ b/libview/ev-view-presentation.c
@@ -57,6 +57,7 @@ struct _EvViewPresentation
        GtkWidget base;
 
        guint                  current_page;
+       cairo_surface_t       *current_surface;
        EvDocument            *document;
        guint                  rotation;
        EvPresentationState    state;
@@ -291,7 +292,9 @@ ev_view_presentation_animation_start (EvViewPresentation *pview,
        pview->animation = ev_transition_animation_new (effect);
 
        surface = EV_JOB_RENDER (pview->curr_job)->surface;
-       ev_transition_animation_set_origin_surface (pview->animation, surface);
+       ev_transition_animation_set_origin_surface (pview->animation,
+                                                   surface != NULL ?
+                                                   surface : pview->current_surface);
 
        jump = new_page - pview->current_page;
        if (jump == -1)
@@ -877,6 +880,19 @@ ev_view_presentation_hide_cursor_timeout_start (EvViewPresentation *pview)
                                       pview);
 }
 
+static void
+ev_view_presentation_update_current_surface (EvViewPresentation *pview,
+                                            cairo_surface_t    *surface)
+{
+       if (!surface || pview->current_surface == surface)
+               return;
+
+       cairo_surface_reference (surface);
+       if (pview->current_surface)
+               cairo_surface_destroy (pview->current_surface);
+       pview->current_surface = surface;
+}
+
 static void
 ev_view_presentation_destroy (GtkObject *object)
 {
@@ -906,6 +922,11 @@ ev_view_presentation_destroy (GtkObject *object)
                pview->next_job = NULL;
        }
 
+       if (pview->current_surface) {
+               cairo_surface_destroy (pview->current_surface);
+               pview->current_surface = NULL;
+       }
+
        if (pview->page_cache) {
                g_object_unref (pview->page_cache);
                pview->page_cache = NULL;
@@ -1026,8 +1047,13 @@ ev_view_presentation_expose_event (GtkWidget      *widget,
        }
 
        surface = pview->curr_job ? EV_JOB_RENDER (pview->curr_job)->surface : NULL;
-       if (!surface)
+       if (surface) {
+               ev_view_presentation_update_current_surface (pview, surface);
+       } else if (pview->current_surface) {
+               surface = pview->current_surface;
+       } else {
                return FALSE;
+       }
 
        ev_view_presentation_get_page_area (pview, &page_area);
        if (gdk_rectangle_intersect (&page_area, &(event->area), &overlap)) {