plug-ins: #5896. add option for reversing order of layers when importing PDF

This feature adds new 'Load in reverse order' toggle box to allow
selection of order of PDF pages before importing them as a layers or
images.

Adds new bool parameter 'reverse-order' to Non-interactive mode.
Order of parameters was also changed from (password, n-pages, pages)
to (password, reverse-order, n-pages, pages)

plug-ins/common/file-pdf-load.c

@@ -197,15 +197,17 @@ typedef struct
   GimpPageSelectorTarget  target;
   gdouble                 resolution;
   gboolean                antialias;
+  gboolean                reverse_order;
   gchar                  *PDF_password;
 } PdfLoadVals;
 
 static PdfLoadVals loadvals =
 {
   GIMP_PAGE_SELECTOR_TARGET_LAYERS,
-  100.00,  /* 100 dpi   */
-  TRUE,
-  NULL
+  100.00,  /* resolution in dpi   */
+  TRUE,    /* antialias */
+  FALSE,   /* reverse_order */
+  NULL     /* pdf_password */
 };
 
 typedef struct
@@ -255,6 +257,7 @@ static GimpImage       * load_image          (PopplerDocument      *doc,
                                               GimpPageSelectorTarget target,
                                               gdouble               resolution,
                                               gboolean              antialias,
+                                              gboolean              reverse_order,
                                               PdfSelectedPages     *pages);
 
 static GimpPDBStatusType load_dialog         (PopplerDocument      *doc,
@@ -354,6 +357,12 @@ pdf_create_procedure (GimpPlugIn  *plug_in,
                             NULL,
                             G_PARAM_READWRITE);
 
+      GIMP_PROC_ARG_BOOLEAN (procedure, "reverse-order",
+                             "Load in reverse order",
+                             "Load PDF pages in reverse order",
+                             FALSE,
+                             G_PARAM_READWRITE);
+
       GIMP_PROC_ARG_INT (procedure, "n-pages",
                          "N pages",
                          "Number of pages to load (0 for all)",
@@ -435,6 +444,8 @@ pdf_load (GimpProcedure        *procedure,
                            GIMP_VALUES_GET_STRING (args, 0),
                            run_mode, &error);
 
+      loadvals.reverse_order = GIMP_VALUES_GET_BOOLEAN (args, 1);
+
       if (doc)
         {
           PopplerPage *test_page = poppler_document_get_page (doc, 0);
@@ -452,7 +463,7 @@ pdf_load (GimpProcedure        *procedure,
                * "pages" argument.
                * Not ceiling this value is *not* an error.
                */
-              pages.n_pages = GIMP_VALUES_GET_INT (args, 1);
+              pages.n_pages = GIMP_VALUES_GET_INT (args, 2);
               if (pages.n_pages <= 0)
                 {
                   pages.n_pages = doc_n_pages;
@@ -462,7 +473,7 @@ pdf_load (GimpProcedure        *procedure,
                 }
               else
                 {
-                  const gint32 *p = GIMP_VALUES_GET_INT32_ARRAY (args, 2);
+                  const gint32 *p = GIMP_VALUES_GET_INT32_ARRAY (args, 3);
 
                   pages.pages = g_new (gint, pages.n_pages);
 
@@ -511,6 +522,7 @@ pdf_load (GimpProcedure        *procedure,
                           loadvals.target,
                           loadvals.resolution,
                           loadvals.antialias,
+                          loadvals.reverse_order,
                           &pages);
     }
 
@@ -785,6 +797,7 @@ load_image (PopplerDocument        *doc,
             GimpPageSelectorTarget  target,
             gdouble                 resolution,
             gboolean                antialias,
+            gboolean                reverse_order,
             PdfSelectedPages       *pages)
 {
   GimpImage  *image = NULL;
@@ -792,6 +805,14 @@ load_image (PopplerDocument        *doc,
   gint        i;
   gdouble     scale;
   gdouble     doc_progress = 0;
+  gint        base_index = 0;
+  gint        sign = 1;
+
+  if (reverse_order && pages->n_pages > 0)
+    {
+      base_index = pages->n_pages - 1;
+      sign = -1;
+    }
 
   if (target == GIMP_PAGE_SELECTOR_TARGET_IMAGES)
     images = g_new0 (GimpImage *, pages->n_pages);
@@ -813,8 +834,11 @@ load_image (PopplerDocument        *doc,
       cairo_surface_t *surface;
       gint             width;
       gint             height;
+      gint             page_index;
 
-      page = poppler_document_get_page (doc, pages->pages[i]);
+      page_index = base_index + sign * i;
+
+      page = poppler_document_get_page (doc, pages->pages[page_index]);
 
       poppler_page_get_size (page, &page_width, &page_height);
       width  = page_width  * scale;
@@ -1020,6 +1044,8 @@ load_dialog (PopplerDocument  *doc,
   GtkWidget  *resolution;
   GtkWidget  *antialias;
   GtkWidget  *hbox;
+  GtkWidget  *reverse_order;
+  GtkWidget  *separator;
 
   ThreadData  thread_data;
   GThread    *thread;
@@ -1109,8 +1135,21 @@ load_dialog (PopplerDocument  *doc,
 
   thread = g_thread_new ("thumbnailer", thumbnail_thread, &thread_data);
 
-  /* Resolution */
+  /* "Load in reverse order" toggle button */
+  reverse_order = gtk_check_button_new_with_mnemonic (_("Load in reverse order"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (reverse_order), loadvals.reverse_order);
+  gtk_box_pack_start (GTK_BOX (vbox), reverse_order, FALSE, FALSE, 0);
+
+  g_signal_connect (reverse_order, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update), &loadvals.reverse_order);
+  gtk_widget_show (reverse_order);
 
+  /* Separator */
+  separator = gtk_separator_new (GTK_ORIENTATION_HORIZONTAL);
+  gtk_box_pack_start (GTK_BOX (vbox), separator, FALSE, FALSE, 0);
+  gtk_widget_show (separator);
+
+  /* Resolution */
   hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
   gtk_box_pack_start (GTK_BOX (vbox), hbox, FALSE, FALSE, 0);
   gtk_widget_show (hbox);