gel.window: Add support for a Gtk window.

4-high/gel/source/platform/gtk/gel-window-gtk.ads

@@ -0,0 +1,72 @@
+with
+     gtk.glArea;
+
+private
+with
+     gdk.glContext;
+
+
+package gel.Window.gtk
+--
+-- Provides a GTK implementation of a window.
+--
+is
+   type Item is new gel.Window.item with private;
+   type View is access all Item'Class;
+
+
+
+   ---------
+   --- Forge
+   --
+
+   procedure define  (Self : access Item;   Title  : in String;
+                                            Width  : in Natural;
+                                            Height : in Natural);
+   overriding
+   procedure destroy (Self : in out Item);
+
+
+   package Forge
+   is
+      function new_Window (Title  : in String;
+                           Width  : in Natural;
+                           Height : in Natural) return Window.gtk.view;
+   end Forge;
+
+
+
+   --------------
+   --- Attributes
+   --
+
+   package std_gtk renames standard.GTK;
+
+   function gl_Area (Self : in Item) return std_gtk.GLArea.Gtk_GLArea;
+
+
+
+   --------------
+   --- Operations
+   --
+
+   overriding
+   procedure enable_GL   (Self : in     Item);
+   overriding
+   procedure disable_GL  (Self : in     Item);
+   overriding
+   procedure swap_GL     (Self : in out Item);
+   overriding
+   procedure freshen     (Self : in     Item);
+
+
+
+private
+
+   type Item is new gel.Window.item with
+      record
+         gl_Area    : std_gtk.glArea   .gtk_glArea;
+         gl_Context :     gdk.glContext.gdk_glContext;
+      end record;
+
+end gel.Window.gtk;