[evince] djvu: Implement ev_document_get_thumbnail_surface

[Carlos Garcia Campos <carlosgc src gnome org>]

commit 168877438f22b0cb892219d4b670351fe8094b4e
Author: Carlos Garcia Campos <carlosgc gnome org>
Date:   Sat Mar 22 12:46:09 2014 +0100

    djvu: Implement ev_document_get_thumbnail_surface

 backend/djvu/djvu-document.c |   50 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 50 insertions(+), 0 deletions(-)
---
diff --git a/backend/djvu/djvu-document.c b/backend/djvu/djvu-document.c
index 709db41..13402f6 100644
--- a/backend/djvu/djvu-document.c
+++ b/backend/djvu/djvu-document.c
@@ -470,6 +470,55 @@ djvu_document_get_thumbnail (EvDocument      *document,
        return rotated_pixbuf;
 }
 
+static cairo_surface_t *
+djvu_document_get_thumbnail_surface (EvDocument      *document,
+                                    EvRenderContext *rc)
+{
+       DjvuDocument *djvu_document = DJVU_DOCUMENT (document);
+       cairo_surface_t *surface, *rotated_surface;
+       gdouble page_width, page_height;
+       gint thumb_width, thumb_height;
+       gchar *pixels;
+       gint thumbnail_rendered;
+
+       g_return_val_if_fail (djvu_document->d_document, NULL);
+
+       djvu_document_get_page_size (EV_DOCUMENT(djvu_document), rc->page,
+                                    &page_width, &page_height);
+
+       thumb_width = (gint) (page_width * rc->scale + 0.5);
+       thumb_height = (gint) (page_height * rc->scale + 0.5);
+
+       surface = cairo_image_surface_create (CAIRO_FORMAT_RGB24,
+                                             thumb_width, thumb_height);
+       pixels = (gchar *)cairo_image_surface_get_data (surface);
+
+       while (ddjvu_thumbnail_status (djvu_document->d_document, rc->page->index, 1) < DDJVU_JOB_OK)
+               djvu_handle_events(djvu_document, TRUE, NULL);
+
+       thumbnail_rendered = ddjvu_thumbnail_render (djvu_document->d_document,
+                                                    rc->page->index,
+                                                    &thumb_width, &thumb_height,
+                                                    djvu_document->d_format,
+                                                    cairo_image_surface_get_stride (surface),
+                                                    pixels);
+
+       if (!thumbnail_rendered) {
+               cairo_surface_destroy (surface);
+               surface = djvu_document_render (document, rc);
+       } else {
+               cairo_surface_mark_dirty (surface);
+               rotated_surface = ev_document_misc_surface_rotate_and_scale (surface,
+                                                                            thumb_width,
+                                                                            thumb_height,
+                                                                            rc->rotation);
+               cairo_surface_destroy (surface);
+               surface = rotated_surface;
+       }
+
+       return surface;
+}
+
 static void
 djvu_document_finalize (GObject *object)
 {
@@ -513,6 +562,7 @@ djvu_document_class_init (DjvuDocumentClass *klass)
        ev_document_class->get_page_size = djvu_document_get_page_size;
        ev_document_class->render = djvu_document_render;
        ev_document_class->get_thumbnail = djvu_document_get_thumbnail;
+       ev_document_class->get_thumbnail_surface = djvu_document_get_thumbnail_surface;
 }
 
 static gchar *