[gimp] Issue #4425: Saving to PDF changes text's font and size.

[Jehan <jehanp src gnome org>]

commit 1b0606716488dfd8839396fecd7e1f5c95cb95b7
Author: Jehan <jehan girinstud io>
Date:   Wed Jan 1 17:53:02 2020 +0100

    Issue #4425: Saving to PDF changes text's font and size.
    
    Adds a new PDF export option "Convert text layers to image", which
    defaults to FALSE (because text staying text is obviously usually
    prefered).
    Also loop through text layers to detect missing fonts. In case any are
    found, add a warning in the export dialog, below the new option,
    advising to enable this option if design matters (if fonts are missing,
    PangoCairo seems to select any other random font and embed it into the
    PDF instead of the expected one).

 plug-ins/common/file-pdf-save.c | 137 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 134 insertions(+), 3 deletions(-)
---
diff --git a/plug-ins/common/file-pdf-save.c b/plug-ins/common/file-pdf-save.c
index 276d4dad86..088c4fa81e 100644
--- a/plug-ins/common/file-pdf-save.c
+++ b/plug-ins/common/file-pdf-save.c
@@ -144,7 +144,8 @@ typedef enum
   SA_IGNORE_HIDDEN,
   SA_APPLY_MASKS,
   SA_LAYERS_AS_PAGES,
-  SA_REVERSE_ORDER
+  SA_REVERSE_ORDER,
+  SA_CONVERT_TEXT
 } SaveArgs;
 
 typedef enum
@@ -165,6 +166,7 @@ typedef struct
   gboolean apply_masks;
   gboolean layers_as_pages;
   gboolean reverse_order;
+  gboolean convert_text;
 } PdfOptimize;
 
 typedef struct
@@ -297,7 +299,8 @@ static PdfOptimize optimize =
   TRUE,  /* ignore_hidden */
   TRUE,  /* apply_masks */
   FALSE, /* layers_as_pages */
-  FALSE  /* reverse_order */
+  FALSE, /* reverse_order */
+  FALSE  /* convert text layers to raster */
 };
 
 static GtkTreeModel *model;
@@ -396,6 +399,12 @@ pdf_create_procedure (GimpPlugIn  *plug_in,
                              "Reverse the pages order (top layers first).",
                              FALSE,
                              G_PARAM_READWRITE);
+
+      GIMP_PROC_ARG_BOOLEAN (procedure, "convert-text-layers",
+                             "Convert text layers to image",
+                             "Convert text layers to raster graphics",
+                             FALSE,
+                             G_PARAM_READWRITE);
     }
   else if (! strcmp (name, SAVE_MULTI_PROC))
     {
@@ -499,6 +508,7 @@ pdf_save (GimpProcedure        *procedure,
       optimize.ignore_hidden   = GIMP_VALUES_GET_BOOLEAN (args, SA_IGNORE_HIDDEN);
       optimize.layers_as_pages = GIMP_VALUES_GET_BOOLEAN (args, SA_LAYERS_AS_PAGES);
       optimize.reverse_order   = GIMP_VALUES_GET_BOOLEAN (args, SA_REVERSE_ORDER);
+      optimize.convert_text    = GIMP_VALUES_GET_BOOLEAN (args, SA_CONVERT_TEXT);
     }
   else
     defaults = TRUE;
@@ -631,6 +641,62 @@ write_func (void                *fp,
                                             : CAIRO_STATUS_WRITE_ERROR;
 }
 
+static GList *
+get_missing_fonts (GList *layers)
+{
+  GList *missing_fonts = NULL;
+  GList *iter;
+
+  for (iter = layers; iter; iter = iter->next)
+    {
+      GimpLayer *layer = iter->data;
+
+      if (gimp_item_is_group (GIMP_ITEM (layer)))
+        {
+          missing_fonts = g_list_concat (missing_fonts,
+                                         get_missing_fonts (gimp_item_list_children (GIMP_ITEM (layer))));
+        }
+      else if (gimp_item_is_text_layer (GIMP_ITEM (layer)))
+        {
+          gchar                *font_family;
+          PangoFontDescription *font_description;
+          PangoFontDescription *font_description2;
+          PangoFontMap         *fontmap;
+          PangoFont            *font;
+          PangoContext         *context;
+
+          fontmap = pango_cairo_font_map_new_for_font_type (CAIRO_FONT_TYPE_FT);
+          context = pango_font_map_create_context (fontmap);
+
+          font_family = gimp_text_layer_get_font (layer);
+          font_description = pango_font_description_from_string (font_family);
+
+          font = pango_font_map_load_font (fontmap, context, font_description);
+          font_description2 = pango_font_describe (font);
+          if (g_strcmp0 (pango_font_description_get_family (font_description),
+                         pango_font_description_get_family (font_description2)) != 0)
+            {
+              const gchar *missing = pango_font_description_get_family (font_description);
+
+              if (g_list_find_custom (missing_fonts, missing, (GCompareFunc) g_strcmp0) == NULL)
+                missing_fonts = g_list_prepend (missing_fonts,
+                                                g_strdup (missing));
+            }
+
+          g_object_unref (font);
+          pango_font_description_free (font_description);
+          pango_font_description_free (font_description2);
+          g_free (font_family);
+          g_object_unref (context);
+          g_object_unref (fontmap);
+        }
+    }
+
+  g_list_free (layers);
+
+  return missing_fonts;
+}
+
 static GimpValueArray *
 pdf_save_image (GimpProcedure *procedure,
                 gboolean       single_image,
@@ -864,11 +930,13 @@ gui_single (void)
   GtkWidget *vbox;
   GtkWidget *vectorize_c;
   GtkWidget *ignore_hidden_c;
+  GtkWidget *convert_text_c;
   GtkWidget *apply_c;
   GtkWidget *layers_as_pages_c;
   GtkWidget *reverse_order_c;
   GtkWidget *frame;
   gchar     *text;
+  GList     *missing_fonts;
   gboolean   run;
   gint32     n_layers;
 
@@ -882,6 +950,67 @@ gui_single (void)
 
   gtk_container_set_border_width (GTK_CONTAINER (window), 12);
 
+  convert_text_c = gtk_check_button_new_with_mnemonic (_("_Convert text layers to image"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (convert_text_c),
+                                optimize.convert_text);
+  missing_fonts = get_missing_fonts (gimp_image_list_layers (multi_page.images[0]));
+  if (missing_fonts != NULL)
+    {
+      GtkWidget *label;
+      GtkWidget *image;
+      GtkWidget *warn_box;
+      GList     *iter;
+      gchar     *font_list = NULL;
+
+      frame = gtk_frame_new (NULL);
+      gtk_box_pack_end (GTK_BOX (vbox), frame, TRUE, TRUE, 0);
+
+      /* Checkbox is frame label. */
+      gtk_frame_set_label_widget (GTK_FRAME (frame), convert_text_c);
+
+      /* Show warning inside the frame. */
+      warn_box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 4);
+      gtk_container_add (GTK_CONTAINER (frame), warn_box);
+
+      image = gtk_image_new_from_icon_name (GIMP_ICON_WILBER_EEK,
+                                            GTK_ICON_SIZE_BUTTON);
+      gtk_box_pack_start (GTK_BOX (warn_box), image, FALSE, FALSE, 0);
+      gtk_widget_show (image);
+
+      for (iter = missing_fonts; iter; iter = iter->next)
+        {
+          gchar *fontname = iter->data;
+
+          if (font_list == NULL)
+            {
+              font_list = g_strdup (fontname);
+            }
+          else
+            {
+              gchar *tmp = font_list;
+
+              font_list = g_strjoin (", ", tmp, fontname, NULL);
+              g_free (tmp);
+            }
+        }
+
+      text = g_strdup_printf (_("The following fonts cannot be found: %s.\n"
+                                "It is recommended to convert your text layers to image "
+                                "or to install the missing fonts before exporting, "
+                                "otherwise your design may not look right."),
+                              font_list);
+      label = gtk_label_new (text);
+      gtk_label_set_line_wrap (GTK_LABEL (label), TRUE);
+      g_free (text);
+      gtk_box_pack_start (GTK_BOX (warn_box), label, TRUE, TRUE, 0);
+
+      g_list_free_full (missing_fonts, g_free);
+    }
+  else
+    {
+      gtk_box_pack_end (GTK_BOX (vbox), convert_text_c, TRUE, TRUE, 0);
+    }
+
   ignore_hidden_c = gtk_check_button_new_with_mnemonic (_("_Omit hidden layers and layers with zero 
opacity"));
   gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (ignore_hidden_c),
                                 optimize.ignore_hidden);
@@ -935,6 +1064,8 @@ gui_single (void)
 
   run = gtk_dialog_run (GTK_DIALOG (window)) == GTK_RESPONSE_OK;
 
+  optimize.convert_text =
+    gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (convert_text_c));
   optimize.ignore_hidden =
     gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (ignore_hidden_c));
   optimize.vectorize =
@@ -1802,7 +1933,7 @@ draw_layer (GimpLayer   **layers,
 
           gimp_drawable_offsets (GIMP_DRAWABLE (layer), &x, &y);
 
-          if (! gimp_item_is_text_layer (GIMP_ITEM (layer)))
+          if (! gimp_item_is_text_layer (GIMP_ITEM (layer)) || optimize.convert_text)
             {
               /* For raster layers */