init dragdrop

contains a new class simple_dragdrop and changes of listbox for dragdrop

include/nana/gui/basis.hpp

@@ -65,6 +65,13 @@ namespace nana
 		blend
 	};
 
+	enum class dragdrop_status
+	{
+		not_ready,
+		ready,
+		in_progress
+	};
+
 	namespace category
 	{
 		enum class flags

include/nana/gui/detail/basic_window.hpp

@@ -1,7 +1,7 @@
 /**
  *	A Basic Window Widget Definition
  *	Nana C++ Library(http://www.nanapro.org)
- *	Copyright(C) 2003-2017 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2018 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0.
  *	(See accompanying file LICENSE_1_0.txt or copy at
@@ -179,7 +179,8 @@ namespace detail
 			bool ignore_menubar_focus	: 1;	///< A flag indicates whether the menubar sets the focus.
 			bool ignore_mouse_focus		: 1;	///< A flag indicates whether the widget accepts focus when clicking on it
 			bool space_click_enabled : 1;		///< A flag indicates whether enable mouse_down/click/mouse_up when pressing and releasing whitespace key.
-			unsigned Reserved	:18;
+			bool draggable : 1;
+			unsigned Reserved	:17;
 			unsigned char tab;		///< indicate a window that can receive the keyboard TAB
 			mouse_action	action;
 			mouse_action	action_before;
@@ -234,6 +235,7 @@ namespace detail
 											///< if the active_window is null, the parent of this window keeps focus.
 			paint::graphics glass_buffer;	///< if effect.bground is avaiable. Refer to window_layout::make_bground.
 			update_state	upd_state;
+			dragdrop_status	dnd_state{ dragdrop_status::not_ready };
 
 			union
 			{

include/nana/gui/dragdrop.hpp

@@ -0,0 +1,45 @@
+/**
+*	Drag and Drop Implementation
+*	Nana C++ Library(http://www.nanapro.org)
+*	Copyright(C) 2018 Jinhao(cnjinhao@hotmail.com)
+*
+*	Distributed under the Boost Software License, Version 1.0.
+*	(See accompanying file LICENSE_1_0.txt or copy at
+*	http://www.boost.org/LICENSE_1_0.txt)
+*
+*	@file: nana/gui/dragdrop.hpp
+*	@author: Jinhao(cnjinhao@hotmail.com)
+*/
+#ifndef NANA_GUI_DRAGDROP_INCLUDED
+#define NANA_GUI_DRAGDROP_INCLUDED
+
+#include <nana/push_ignore_diagnostic>
+#include <functional>
+#include "basis.hpp"
+
+#include <memory>
+
+namespace nana
+{
+	class simple_dragdrop
+	{
+		struct implementation;
+
+		simple_dragdrop(const simple_dragdrop&) = delete;
+		simple_dragdrop& operator=(const simple_dragdrop&) = delete;
+
+		simple_dragdrop(simple_dragdrop&&) = delete;
+		simple_dragdrop& operator=(simple_dragdrop&&) = delete;
+	public:
+		simple_dragdrop(window drag_wd);
+		~simple_dragdrop();
+
+		/// Sets a condition that determines whether the drag&drop can start
+		void condition(std::function<bool()> predicate_fn);
+		void make_drop(window target, std::function<void()> drop_fn);
+	private:
+		implementation* const impl_;
+	};
+}
+
+#endif

include/nana/gui/programming_interface.hpp

@@ -1,7 +1,7 @@
 /*
  *	Nana GUI Programming Interface Implementation
  *	Nana C++ Library(http://www.nanapro.org)
- *	Copyright(C) 2003-2017 Jinhao(cnjinhao@hotmail.com)
+ *	Copyright(C) 2003-2018 Jinhao(cnjinhao@hotmail.com)
  *
  *	Distributed under the Boost Software License, Version 1.0.
  *	(See accompanying file LICENSE_1_0.txt or copy at
@@ -117,6 +117,9 @@ namespace API
 		void lazy_refresh();
 
 		void draw_shortkey_underline(paint::graphics&, const std::string& text, wchar_t shortkey, std::size_t shortkey_position, const point& text_pos, const color&);
+
+		void window_draggable(window, bool enabled);
+		bool window_draggable(window);
 	}//end namespace dev
 
 
@@ -476,6 +479,8 @@ namespace API
 	::std::optional<std::pair<::nana::size, ::nana::size>> content_extent(window wd, unsigned limited_px, bool limit_width);
 
 	unsigned screen_dpi(bool x_requested);
+
+	dragdrop_status window_dragdrop_status(::nana::window);
 }//end namespace API
 
 }//end namespace nana

include/nana/gui/widgets/listbox.hpp

@@ -1497,6 +1497,9 @@ the nana::detail::basic_window member pointer scheme
 		void erase(index_pairs indexes);	///<Erases specified items.
 		item_proxy erase(item_proxy);
 
+		/// Returns the item which is hovered
+		index_pair hovered() const;
+
 		bool sortable() const;
 		void sortable(bool enable);