[gimp] plug-ins: improve a bit PDF export progression.

[Jehan <jehanp src gnome org>]

commit e88107153cd919b3363b8b3ab914ef702e97a70e
Author: Jehan <jehan girinstud io>
Date:   Mon Feb 15 22:21:30 2021 +0100

    plug-ins: improve a bit PDF export progression.
    
    Subdivise progression steps inside layer groups.
    
    It is not perfect yet as it would not handle perfectly weird edge cases
    where you have for instance a lot of layers in a top layer group with
    only many other top layers. But it would still handle it better than
    before. Ideally we should simply count all non-group "leaf" layers in
    the layer tree and use this as the number of steps. In other words, we
    should do a first pass through the whole layer tree.

 plug-ins/common/file-pdf-save.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)
---
diff --git a/plug-ins/common/file-pdf-save.c b/plug-ins/common/file-pdf-save.c
index be854c81ef..76e2c77588 100644
--- a/plug-ins/common/file-pdf-save.c
+++ b/plug-ins/common/file-pdf-save.c
@@ -284,6 +284,9 @@ static gboolean         draw_layer               (GimpLayer           **layers,
                                                   gdouble               x_res,
                                                   gdouble               y_res,
                                                   const gchar          *name,
+                                                  gboolean              show_progress,
+                                                  gdouble               progress_start,
+                                                  gdouble               progress_end,
                                                   GError              **error);
 
 
@@ -855,14 +858,14 @@ pdf_save_image (GimpProcedure *procedure,
       /* Now, we should loop over the layers of each image */
       for (j = 0; j < n_layers; j++)
         {
-          if (show_progress)
-            /* Progression is showed per image, and would restart at 0
-             * if you open several images.
-             */
-            gimp_progress_update ((gdouble) j / n_layers);
-
           if (! draw_layer (layers, n_layers, j, cr, x_res, y_res,
                             gimp_procedure_get_name (procedure),
+                            show_progress,
+                            /* Progression is showed per image, and would restart at 0
+                             * if you open several images.
+                             */
+                            (gdouble) j / n_layers,
+                            (gdouble) (j + 1) / n_layers,
                             &error))
             {
               /* free the resources */
@@ -1916,6 +1919,9 @@ draw_layer (GimpLayer   **layers,
             gdouble       x_res,
             gdouble       y_res,
             const gchar  *name,
+            gboolean      show_progress,
+            gdouble       progress_start,
+            gdouble       progress_end,
             GError      **error)
 {
   GimpLayer *layer;
@@ -1941,7 +1947,11 @@ draw_layer (GimpLayer   **layers,
       for (i = 0; i < children_num; i++)
         {
           if (! draw_layer ((GimpLayer **) children, children_num, i,
-                            cr, x_res, y_res, name, error))
+                            cr, x_res, y_res, name,
+                            show_progress,
+                            progress_start + i * (progress_end - progress_start) / children_num,
+                            progress_end,
+                            error))
             {
               g_free (children);
               return FALSE;
@@ -1955,6 +1965,9 @@ draw_layer (GimpLayer   **layers,
       GimpLayerMask   *mask       = NULL;
       gint             x, y;
 
+      if (show_progress)
+        gimp_progress_update (progress_start);
+
       mask = gimp_layer_get_mask (layer);
       if (mask)
         {