add scheme for checkbox square box

include/nana/gui/detail/widget_geometrics.hpp

@@ -1,7 +1,7 @@
 /*
 *	Widget Geometrics
 *	Nana C++ Library(http://www.nanapro.org)
-*	Copyright(C) 2003-2016 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
@@ -22,12 +22,17 @@ namespace nana
 	public:
 		color_proxy(const color_proxy&);
 		color_proxy(color_rgb);
+		color_proxy(color_argb);
+		color_proxy(color_rgba);
 		color_proxy(colors);
 		color_proxy& operator=(const color_proxy&);
 		color_proxy& operator=(const ::nana::color&);
 		color_proxy& operator=(color_rgb);
+		color_proxy& operator=(color_argb);
+		color_proxy& operator=(color_rgba);
 		color_proxy& operator=(colors);
 		color get_color() const;
+		color get(const color& default_color) const;
 		operator color() const;
 	private:
 		std::shared_ptr<color> color_;

include/nana/gui/widgets/checkbox.hpp

@@ -37,6 +37,13 @@ namespace drawerbase
 {
 	namespace checkbox
 	{
+		struct scheme
+			: public widget_geometrics
+		{
+			color_proxy square_bgcolor{ static_cast<color_argb>(0x0) };
+			color_proxy square_border_color{ colors::black };
+		};
+
 		struct events_type
 			: public general_events
 		{
@@ -67,7 +74,7 @@ namespace drawerbase
 
 	
     class checkbox
-		: public widget_object<category::widget_tag, drawerbase::checkbox::drawer, drawerbase::checkbox::events_type>
+		: public widget_object<category::widget_tag, drawerbase::checkbox::drawer, drawerbase::checkbox::events_type, drawerbase::checkbox::scheme>
 	{
 	public:
 		checkbox();

source/gui/detail/color_schemes.cpp

@@ -1,7 +1,7 @@
 /*
 *	Color Schemes
 *	Nana C++ Library(http://www.nanapro.org)
-*	Copyright(C) 2003-2016 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
@@ -24,6 +24,14 @@ namespace nana
 			: color_(std::make_shared<color>(clr))
 		{}
 
+		color_proxy::color_proxy(color_argb clr)
+			: color_(std::make_shared<color>(clr))
+		{}
+
+		color_proxy::color_proxy(color_rgba clr)
+			: color_(std::make_shared<color>(clr))
+		{}
+
 		color_proxy::color_proxy(colors clr)
 			: color_(std::make_shared<color>(clr))
 		{}
@@ -47,6 +55,18 @@ namespace nana
 			return *this;
 		}
 
+		color_proxy& color_proxy::operator = (color_argb clr)
+		{
+			color_ = std::make_shared<::nana::color>(clr);
+			return *this;
+		}
+
+		color_proxy& color_proxy::operator = (color_rgba clr)
+		{
+			color_ = std::make_shared<::nana::color>(clr);
+			return *this;
+		}
+
 		color_proxy& color_proxy::operator = (colors clr)
 		{
 			color_ = std::make_shared<::nana::color>(clr);
@@ -58,6 +78,13 @@ namespace nana
 			return *color_;
 		}
 
+		color color_proxy::get(const color& default_color) const
+		{
+			if (color_->invisible())
+				return default_color;
+			return *color_;
+		}
+
 		color_proxy::operator color() const
 		{
 			return *color_;

source/gui/widgets/checkbox.cpp

@@ -24,6 +24,7 @@ namespace nana{ namespace drawerbase
 		struct drawer::implement
 		{
 			widget * widget_ptr;
+			scheme * scheme_ptr;
 			bool react;
 			bool radio;
 			facade<element::crook> crook;
@@ -47,6 +48,7 @@ namespace nana{ namespace drawerbase
 			void drawer::attached(widget_reference widget, graph_reference)
 			{
 				impl_->widget_ptr = &widget;
+				impl_->scheme_ptr =static_cast<scheme*>(API::dev::get_scheme(widget));
 				API::dev::enable_space_click(widget, true);
 			}
 
@@ -78,12 +80,14 @@ namespace nana{ namespace drawerbase
 				}
 
 				//draw crook
-#ifdef _nana_std_has_string_view
+
-				auto txt_px = graph.text_extent_size(std::wstring_view( L"jN", 2 )).height + 2;
+				unsigned txt_px = 0, descent = 0, ileading = 0;
-#else
+				graph.text_metrics(txt_px, descent, ileading);
-				auto txt_px = graph.text_extent_size(L"jN", 2).height + 2;
+				txt_px += (descent + 2);
-#endif
+
-				impl_->crook.draw(graph, wdg->bgcolor(), wdg->fgcolor(), rectangle(0, txt_px > 16 ? (txt_px - 16) / 2 : 0, 16, 16), API::element_state(*wdg));
+				impl_->crook.draw(graph,
+					impl_->scheme_ptr->square_bgcolor.get(wdg->bgcolor()), impl_->scheme_ptr->square_border_color.get(wdg->fgcolor()),
+					rectangle(0, txt_px > 16 ? (txt_px - 16) / 2 : 0, 16, 16), API::element_state(*wdg));
 			}
 
 			void drawer::mouse_down(graph_reference graph, const arg_mouse&)