[pangomm] Add the CairoFontMapImpl class

[Kjell Ahlstedt <kjellahl src gnome org>]

commit c27227177a19fb8d5095cc24ce974dd00a88c1bf
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Mon Oct 11 15:48:46 2021 +0200

    Add the CairoFontMapImpl class
    
    * pango/pangomm/.gitignore:
    * pango/pangomm/filelist.am:
    * pango/pangomm/meson.build: Add cairofontmapimpl.
    * pango/src/cairofontmap.hg: Improve the documentation of get_default().
    * pango/src/fontmap.[ccg|hg]: Add a custom wrap_new(). Wrap in a
    CairoFontMapImpl if the PangoFontMap object implements PangoCairoFontMap.
    * pango/pangomm/cairofontmapimpl.[cc|h]: New files. A CairoFontMapImpl
    derives from FontMap and implements CairoFontMap.
    
    Fixes #15

 pango/pangomm/.gitignore          |  2 ++
 pango/pangomm/cairofontmapimpl.cc | 41 +++++++++++++++++++++++++
 pango/pangomm/cairofontmapimpl.h  | 63 +++++++++++++++++++++++++++++++++++++++
 pango/pangomm/filelist.am         | 10 +++++--
 pango/pangomm/meson.build         |  2 ++
 pango/src/cairofontmap.hg         | 33 +++++++++++++++++++-
 pango/src/fontmap.ccg             | 12 +++++++-
 pango/src/fontmap.hg              | 16 ++++++----
 8 files changed, 170 insertions(+), 9 deletions(-)
---
diff --git a/pango/pangomm/.gitignore b/pango/pangomm/.gitignore
index 05b228b..29f0415 100644
--- a/pango/pangomm/.gitignore
+++ b/pango/pangomm/.gitignore
@@ -1,6 +1,8 @@
 /*.cc
+!/cairofontmapimpl.cc
 !/init.cc
 /*.h
+!/cairofontmapimpl.h
 !/init.h
 !/types.h
 !/wrap_init.h
diff --git a/pango/pangomm/cairofontmapimpl.cc b/pango/pangomm/cairofontmapimpl.cc
new file mode 100644
index 0000000..a76441b
--- /dev/null
+++ b/pango/pangomm/cairofontmapimpl.cc
@@ -0,0 +1,41 @@
+/* Copyright (C) 2021 The gtkmm Development Team
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <pangomm/cairofontmapimpl.h>
+#include <utility> // std::move()
+
+namespace Pango
+{
+CairoFontMapImpl::CairoFontMapImpl(PangoFontMap* castitem)
+: Glib::ObjectBase(nullptr), FontMap(castitem)
+{}
+
+CairoFontMapImpl::CairoFontMapImpl(CairoFontMapImpl&& src) noexcept
+: CairoFontMap(std::move(src)),
+  FontMap(std::move(src))
+{}
+
+CairoFontMapImpl& CairoFontMapImpl::operator=(CairoFontMapImpl&& src) noexcept
+{
+  CairoFontMap::operator=(std::move(src));
+  FontMap::operator=(std::move(src));
+  return *this;
+}
+
+CairoFontMapImpl::~CairoFontMapImpl() noexcept
+{}
+
+} // namespace Pango
diff --git a/pango/pangomm/cairofontmapimpl.h b/pango/pangomm/cairofontmapimpl.h
new file mode 100644
index 0000000..9b06122
--- /dev/null
+++ b/pango/pangomm/cairofontmapimpl.h
@@ -0,0 +1,63 @@
+#ifndef _PANGO_CAIROFONTMAPIMPL_H
+#define _PANGO_CAIROFONTMAPIMPL_H
+
+/* Copyright (C) 2021 The gtkmm Development Team
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <pangommconfig.h>
+#include <pangomm/cairofontmap.h>
+#include <pangomm/fontmap.h>
+
+namespace Pango
+{
+
+/** %Gdk::CairoFontMapImpl is a Pango::FontMap that implements the Pango::CairoFontMap interface.
+ *
+ * The PangoCairoFontMap interface can be implemented by C classes that
+ * derive from PangoFontMap. No public %Pango class implements PangoCairoFontMap.
+ * Some %Pango functions, such as pango_cairo_font_map_get_default(), return an object
+ * of a class which is derived from PangoFontMap and implements PangoCairoFontMap.
+ * Since that C class is not public, it's not wrapped in a C++ class.
+ * A C object of such a class can be wrapped in a %Pango::CairoFontMapImpl object.
+ * %Pango::CairoFontMapImpl does not directly correspond to any %Pango class.
+ *
+ * This class is intended only for wrapping C objects returned from %Pango functions.
+ *
+ * @see Pango::CairoFontMap::get_default()
+ * @newin{2,50}
+ */
+class PANGOMM_API CairoFontMapImpl : public CairoFontMap, public FontMap
+{
+#ifndef DOXYGEN_SHOULD_SKIP_THIS
+protected:
+  explicit CairoFontMapImpl(PangoFontMap* castitem);
+  friend class FontMap_Class;
+
+  // noncopyable
+  CairoFontMapImpl(const CairoFontMapImpl&) = delete;
+  CairoFontMapImpl& operator=(const CairoFontMapImpl&) = delete;
+#endif /* DOXYGEN_SHOULD_SKIP_THIS */
+
+public:
+  CairoFontMapImpl(CairoFontMapImpl&& src) noexcept;
+  CairoFontMapImpl& operator=(CairoFontMapImpl&& src) noexcept;
+
+  ~CairoFontMapImpl() noexcept override;
+};
+
+} // namespace Pango
+
+#endif /* _PANGO_CAIROFONTMAPIMPL_H */
diff --git a/pango/pangomm/filelist.am b/pango/pangomm/filelist.am
index 9bf9b89..2138b30 100644
--- a/pango/pangomm/filelist.am
+++ b/pango/pangomm/filelist.am
@@ -2,6 +2,12 @@
 
 files_built_cc = $(files_hg:.hg=.cc) wrap_init.cc
 files_built_h  = $(files_hg:.hg=.h)
-files_extra_cc = init.cc
-files_extra_h  = init.h types.h wrap_init.h
+files_extra_cc = \
+  cairofontmapimpl.cc \
+  init.cc
+files_extra_h = \
+  cairofontmapimpl.h \
+  init.h \
+  types.h \
+  wrap_init.h
 files_extra_ph =
diff --git a/pango/pangomm/meson.build b/pango/pangomm/meson.build
index e6c869a..76deea7 100644
--- a/pango/pangomm/meson.build
+++ b/pango/pangomm/meson.build
@@ -51,10 +51,12 @@ hg_ccg_basenames = [
 ]
 
 extra_cc_files = [
+  'cairofontmapimpl.cc',
   'init.cc',
 ]
 
 extra_h_files = [
+  'cairofontmapimpl.h',
   'init.h',
   'types.h',
   'wrap_init.h',
diff --git a/pango/src/cairofontmap.hg b/pango/src/cairofontmap.hg
index a500c0b..40f303d 100644
--- a/pango/src/cairofontmap.hg
+++ b/pango/src/cairofontmap.hg
@@ -34,14 +34,45 @@ typedef struct _PangoCairoFontMapIface PangoCairoFontMapIface;
 namespace Pango
 {
 
-/** A Pango::CairoFontMap represents the set of fonts available for a particular rendering system.
+/** %Pango::CairoFontMap is an interface implemented by font maps for use with Cairo.
+ *
+ * The actual type of the font map will depend on the particular
+ * font technology Cairo was compiled to use.
  */
 class PANGOMM_API CairoFontMap : public Glib::Interface
 {
    _CLASS_INTERFACE(CairoFontMap, PangoCairoFontMap, PANGO_CAIRO_FONT_MAP, PangoCairoFontMapIface, , , 
PANGOMM_API)
 
 public:
+  /** Gets a default %Pango::CairoFontMap to use with Cairo.
+   *
+   * Note that the type of the returned object will depend
+   * on the particular font backend Cairo was compiled to use.
+   * You generally should only use the Pango::FontMap and
+   * %Pango::CairoFontMap API on the returned object.
+   *
+   * The default Cairo fontmap can be changed by using
+   * set_default(). This can be used to change the Cairo font backend
+   * that the default fontmap uses for example.
+   *
+   * Note that since %Pango 1.32.6, the default fontmap is per-thread.
+   * Each thread gets its own default fontmap. In this way,
+   * PangoCairo can be used safely from multiple threads.
+   *
+   * To use %Pango::CairoFontMap API, do something like
+   * @code
+   * auto font_map = Pango::CairoFontMap::get_default();
+   * auto cairo_font_map = std::dynamic_pointer_cast<Pango::CairoFontMap>(font_map);
+   * if (cairo_font_map)
+   *   cairo_font_map->do_something();
+   * @endcode
+   *
+   * @newin{1,10}
+   *
+   * @return The default PangoCairo fontmap for the current thread.
+   */
   _WRAP_METHOD(static Glib::RefPtr<FontMap> get_default(), pango_cairo_font_map_get_default, refreturn)
+
   _WRAP_METHOD(void set_default(), pango_cairo_font_map_set_default)
 
 #m4 _CONVERSION(`cairo_font_type_t',`Cairo::FontType',`static_cast<Cairo::FontType>($3)')
diff --git a/pango/src/fontmap.ccg b/pango/src/fontmap.ccg
index 0dae2af..e4d9ea6 100644
--- a/pango/src/fontmap.ccg
+++ b/pango/src/fontmap.ccg
@@ -16,11 +16,22 @@
  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+#include <pangomm/cairofontmapimpl.h>
 #include <pangomm/context.h>
+#include <pango/pangocairo.h>
 
 namespace Pango
 {
 
+// Custom wrap_new() because we want to create
+// a CairoFontMapImpl if the underlying C class implements the PangoCairoFontMap interface.
+Glib::ObjectBase* FontMap_Class::wrap_new(GObject* object)
+{
+  if (PANGO_IS_CAIRO_FONT_MAP(object))
+     return new CairoFontMapImpl((PangoFontMap*)object);
+  return new FontMap((PangoFontMap*)object);
+}
+
 std::vector<Glib::RefPtr<FontFamily>> FontMap::list_families() const
 {
   //Get the array:
@@ -33,4 +44,3 @@ std::vector<Glib::RefPtr<FontFamily>> FontMap::list_families() const
 }
 
 } /* namespace Pango */
-
diff --git a/pango/src/fontmap.hg b/pango/src/fontmap.hg
index 353f559..79526d8 100644
--- a/pango/src/fontmap.hg
+++ b/pango/src/fontmap.hg
@@ -32,13 +32,19 @@ namespace Pango
 
 class PANGOMM_API Context;
 
-/** A Pango::FontMap represents the set of fonts available for a particular rendering system.
+/** A %Pango::FontMap represents the set of fonts available for a particular rendering system.
+ *
+ * This is an abstract base class with implementations being specific to
+ * particular rendering systems.
+ *
+ * @see Pango::CairoFontMap::get_default()
  */
 class PANGOMM_API FontMap : public Glib::Object, public Gio::ListModel
 {
-   _CLASS_GOBJECT(FontMap, PangoFontMap, PANGO_FONT_MAP, Glib::Object, GObject, , , PANGOMM_API)
-   _IMPLEMENTS_INTERFACE(Gio::ListModel)
-   _IGNORE(pango_font_map_list_families)
+  _CLASS_GOBJECT(FontMap, PangoFontMap, PANGO_FONT_MAP, Glib::Object, GObject, , , PANGOMM_API)
+  _IMPLEMENTS_INTERFACE(Gio::ListModel)
+  _CUSTOM_WRAP_NEW
+  _IGNORE(pango_font_map_list_families)
 
 public:
   _WRAP_METHOD(Glib::RefPtr<Font> load_font(const Glib::RefPtr<Context>& context, const FontDescription& 
desc) const, pango_font_map_load_font)
@@ -53,7 +59,7 @@ public:
 
   _WRAP_METHOD(guint get_serial() const, pango_font_map_get_serial)
 
-  _IGNORE(pango_font_map_changed)
+  _IGNORE(pango_font_map_changed)dnl// Shall not be used by applications
 };
 
 } /* namespace Pango */