[gtkmm] FontChooser: Add set_filter().

[Murray Cumming <murrayc src gnome org>]

commit 4f449263c21173c7e76cc385a230e671e5521716
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Mar 15 08:53:02 2012 +0100

    FontChooser: Add set_filter().
    
    	* gtk/src/fontchooser.[hg|ccg]: Wrap gtk_font_chooser_set_filter_func()
    	and its callback function (as a slot).

 ChangeLog               |    7 +++++++
 gtk/src/fontchooser.ccg |   42 ++++++++++++++++++++++++++++++++++++++++++
 gtk/src/fontchooser.hg  |   31 +++++++++++++++++++++++++------
 3 files changed, 74 insertions(+), 6 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 04bff47..b0f83e7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2012-03-15  Murray Cumming  <murrayc murrayc com>
+
+	FontChooser: Add set_filter().
+
+	* gtk/src/fontchooser.[hg|ccg]: Wrap gtk_font_chooser_set_filter_func()
+	and its callback function (as a slot).
+
 2012-03-14  Murray Cumming  <murrayc murrayc com>
 
 	PaperSize: Correct the PaperSizeTraits pre-declaration.
diff --git a/gtk/src/fontchooser.ccg b/gtk/src/fontchooser.ccg
index 5d7dafa..633cbc0 100644
--- a/gtk/src/fontchooser.ccg
+++ b/gtk/src/fontchooser.ccg
@@ -17,3 +17,45 @@
 
 #include <gtk/gtk.h>
 
+
+namespace
+{
+extern "C"
+{
+static gboolean SignalProxy_Filter_gtk_callback(const PangoFontFamily* family, const PangoFontFace* face, gpointer user_data)
+{
+  Gtk::FontChooser::SlotFontFilter* the_slot = static_cast<Gtk::FontChooser::SlotFontFilter*>(user_data);
+
+  try
+  {
+    // Create suitable C++ instances to pass to the C++ method:
+    const Glib::RefPtr<const Pango::FontFamily> cppFamily = Glib::wrap(const_cast<PangoFontFamily*>(family), true); 
+    const Glib::RefPtr<const Pango::FontFace> cppFace = Glib::wrap(const_cast<PangoFontFace*>(face), true); 
+    return (*the_slot)(cppFamily, cppFace);
+  }
+  catch(...)
+  {
+    Glib::exception_handlers_invoke();
+  }
+
+  return false; // arbitrary value
+}
+
+static void SignalProxy_Filter_gtk_callback_destroy(void* data)
+{
+  delete static_cast<Gtk::FontChooser::SlotFontFilter*>(data);
+}
+
+} // extern "C"
+} // anonymous namespace
+
+namespace Gtk
+{
+
+void FontChooser::set_filter_func(const SlotFontFilter& slot)
+{
+  SlotFontFilter* slot_copy = new SlotFontFilter(slot);
+  gtk_font_chooser_set_filter_func(gobj(), &SignalProxy_Filter_gtk_callback, slot_copy, &SignalProxy_Filter_gtk_callback_destroy);
+}
+
+} //namespace Gtk
diff --git a/gtk/src/fontchooser.hg b/gtk/src/fontchooser.hg
index 5830318..6b02162 100644
--- a/gtk/src/fontchooser.hg
+++ b/gtk/src/fontchooser.hg
@@ -72,12 +72,31 @@ public:
   _WRAP_METHOD(bool get_show_preview_entry() const, gtk_font_chooser_get_show_preview_entry)
   _WRAP_METHOD(void set_show_preview_entry(bool show_preview_entry = true), gtk_font_chooser_set_show_preview_entry)
 
-/* TODO:
-void             gtk_font_chooser_set_filter_func          (GtkFontChooser   *fontchooser,
-                                                            GtkFontFilterFunc filter,
-                                                            gpointer          user_data,
-                                                            GDestroyNotify    destroy);
-*/
+  /** Font filter callback.
+   * For instance,
+   * @code
+   * bool on_font_fitler(const Glib::RefPtr<const Pango::FontFamily>& font_family, const Glib::RefPtr<const Pango::FontFace>& font_face);
+   * @endcode
+   *
+   * @param font_family A Pango FontFamily.
+   * @param font_face A Font Face belonging to the @a font_family.
+   * @result true if the font should be displayed.
+   *
+   * This is used for deciding what fonts should be shown in a FontChooser.
+   * See set_filter_func().
+   *
+   * @newin{3,4}
+   */
+  typedef sigc::slot<bool, const Glib::RefPtr<const Pango::FontFamily>&, const Glib::RefPtr<const Pango::FontFace>&> SlotFontFilter;
+
+  /** Adds a filter function that decides which fonts to display in the font chooser.
+   *
+   * @param slot A callback, to be called for each font.
+   *
+   * @newin{3,4}
+   */
+  void set_filter_func(const SlotFontFilter& slot);
+  _IGNORE(gtk_font_chooser_set_filter_func)
 
   //TODO: Remove no_default_handler when we can break ABI.
   _WRAP_SIGNAL(void font_activated(const Glib::ustring& fontname), "font-activated", no_default_handler)