gui2: implement widget groups

Groups are handled on a per-dialog basis, and are currently specialized for tselectable_
inheritors. They provide a convenient vector-of-pairs interface that ensure only one
widget is selected at one time and allows binding of values to widgets which can be
fetched at a later point.

projectfiles/CodeBlocks/wesnoth.cbp

@@ -759,6 +759,7 @@
 		<Unit filename="../../src/gui/widgets/grid.cpp" />
 		<Unit filename="../../src/gui/widgets/grid.hpp" />
 		<Unit filename="../../src/gui/widgets/grid_private.hpp" />
+		<Unit filename="../../src/gui/widgets/group.hpp" />
 		<Unit filename="../../src/gui/widgets/helper.cpp" />
 		<Unit filename="../../src/gui/widgets/helper.hpp" />
 		<Unit filename="../../src/gui/widgets/horizontal_scrollbar.cpp" />

src/gui/widgets/group.hpp

@@ -0,0 +1,118 @@
+/*
+   Copyright (C) 2008 - 2016 The Battle for Wesnoth Project http://www.wesnoth.org/
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY.
+
+   See the COPYING file for more details.
+*/
+
+#ifndef GUI_WIDGETS_GROUP_HPP_INCLUDED
+#define GUI_WIDGETS_GROUP_HPP_INCLUDED
+
+#include "gui/auxiliary/event/dispatcher.hpp"
+#include "gui/widgets/selectable.hpp"
+#include "gui/widgets/widget.hpp"
+#include "utils/foreach.tpp"
+
+#include <vector>
+#include <boost/bind.hpp>
+
+namespace gui2
+{
+
+template <class T>
+class tgroup
+{
+public:
+	typedef typename std::vector<std::pair<tselectable_*, T> > group_list;
+	typedef typename group_list::iterator                      group_iterator;
+	typedef typename group_list::const_iterator                group_iterator_const;
+
+	/**
+	 * Adds a widget/value pair to the group vector. A callback is set
+	 * that sets all members' toggle states to false when clicked. This
+	 * happens before individual widget handlers fire, meaning that the
+	 * clicked widget will remain the only one selected.
+	 */
+	void add_member(tselectable_* widget, const T& value)
+	{
+		members_.push_back(std::make_pair(widget, value));
+
+		dynamic_cast<twidget*>(widget)->connect_signal<event::LEFT_BUTTON_CLICK>(boost::bind(
+			&tgroup::group_operator, this), event::tdispatcher::front_child);
+	}
+
+	/**
+	 * Removes a member from the group vector.
+	 *
+	 * TODO: implement
+	void remove_member(tselectable_* widget)
+	{
+	}*/
+
+	/**
+	 * Group member getters
+	 */
+	std::pair<group_iterator, group_iterator> members()
+	{
+		return std::make_pair(members_.begin(), members_.end());
+	}
+
+	std::pair<group_iterator_const, group_iterator_const> members() const
+	{
+		return std::make_pair(members_.begin(), members_.end());
+	}
+
+	/**
+	 * The default actions to take when clicking on one of the widgets
+	 * in the group.
+	 */
+	void group_operator()
+	{
+		FOREACH(AUTO& member, members())
+		{
+			member.first->set_value(false);
+		}
+	}
+
+	/**
+	 * Returns the value paired with the currently activiely toggled member
+	 * of the group.
+	 */
+	T get_active_member_value()
+	{
+		FOREACH(AUTO& member, members())
+		{
+			if(member.first->get_value_bool()) {
+				return member.second;
+			}
+		}
+
+		return T();
+	}
+
+	/**
+	 * Sets the toggle values for all widgets besides the one associated
+	 * with the specified value to false.
+	 */
+	void set_member_states(const T& value)
+	{
+		FOREACH(AUTO& member, members())
+		{
+			member.first->set_value(member.second == value);
+		}
+	}
+
+private:
+	group_list members_;
+
+};
+
+} // namespace gui2
+
+#endif