Merge branch 'feature-draw-through' into develop

source/gui/detail/basic_window.cpp

@@ -292,6 +292,13 @@ namespace nana
 				return false;
 			}
 
+			bool basic_window::is_draw_through() const
+			{
+				if (::nana::category::flags::root == this->other.category)
+					return static_cast<bool>(other.attribute.root->draw_through);
+				return false;
+			}
+
 			void basic_window::_m_init_pos_and_size(basic_window* parent, const rectangle& r)
 			{
 				pos_owner = pos_root = r;

source/gui/detail/win32/bedrock.cpp

@@ -1286,6 +1286,15 @@ namespace detail
 				brock.event_move(msgwnd, (int)(short) LOWORD(lParam), (int)(short) HIWORD(lParam));
 				break;
 			case WM_PAINT:
+				if (msgwnd->is_draw_through())
+				{
+					msgwnd->other.attribute.root->draw_through();
+
+					::PAINTSTRUCT ps;
+					::BeginPaint(root_window, &ps);
+					::EndPaint(root_window, &ps);
+				}
+				else
 				{
 					::PAINTSTRUCT ps;
 					::HDC dc = ::BeginPaint(root_window, &ps);
@@ -1602,6 +1611,26 @@ namespace detail
 		return impl_->estore;
 	}
 
+	void bedrock::map_through_widgets(core_window_t* wd, native_drawable_type drawable)
+	{
+#if defined(NANA_WINDOWS)
+		auto graph_context = reinterpret_cast<HDC>(wd->root_graph->handle()->context);
+
+		for (auto child : wd->children)
+		{
+			if (!child->visible) continue;
+
+			if (::nana::category::flags::widget == child->other.category)
+			{
+				::BitBlt(reinterpret_cast<HDC>(drawable), child->pos_root.x, child->pos_root.y, static_cast<int>(child->dimension.width), static_cast<int>(child->dimension.height),
+					graph_context, child->pos_root.x, child->pos_root.y, SRCCOPY);
+			}
+			else if (::nana::category::flags::lite_widget == child->other.category)
+				map_through_widgets(child, drawable);
+		}
+#endif	
+	}
+
 	bool bedrock::emit(event_code evt_code, core_window_t* wd, const arg_mouse& arg, bool ask_update, thread_context* thrd)
 	{
 		if (evt_code != arg.evt_code)

source/gui/detail/window_manager.cpp

@@ -675,7 +675,7 @@ namespace detail
 		{
 			//Thread-Safe Required!
 			std::lock_guard<decltype(mutex_)> lock(mutex_);
-			if (impl_->wd_register.available(wd))
+			if (impl_->wd_register.available(wd) && !wd->is_draw_through())
 			{
 				//Copy the root buffer that wd specified into DeviceContext
 #if defined(NANA_LINUX)
@@ -739,7 +739,7 @@ namespace detail
 			if (false == impl_->wd_register.available(wd))
 				return false;
 
-			if(wd->visible)
+			if(wd->visible && (!wd->is_draw_through()))
 			{
 				if (wd->visible_parents())
 				{

source/gui/drawing.cpp

@@ -20,19 +20,27 @@ namespace nana
 	//@brief:	This name is only visible for this compiling-unit
 	namespace restrict
 	{
-		typedef detail::bedrock::core_window_t core_window_t;
-		extern detail::bedrock& bedrock;
-
-		inline detail::drawer& get_drawer(window wd)
+		namespace
 		{
-			return reinterpret_cast<core_window_t*>(wd)->drawer;
+			using core_window_t = detail::bedrock::core_window_t;
+
+			inline detail::drawer& get_drawer(window wd)
+			{
+				return reinterpret_cast<core_window_t*>(wd)->drawer;
+			}
 		}
 	}
     
     //class drawing
   		drawing::drawing(window wd)
 			:handle_(wd)
-  		{}
+  		{
+			if (!API::is_window(wd))
+				throw std::invalid_argument("drawing: invalid window parameter");
+
+			if (reinterpret_cast<restrict::core_window_t*>(wd)->is_draw_through())
+				throw std::invalid_argument("drawing: the window is draw_through enabled");
+		}
   		
   		drawing::~drawing(){} //Just for polymorphism
 

source/gui/programming_interface.cpp

@@ -354,6 +354,11 @@ namespace API
 		return (restrict::window_manager.available(reinterpret_cast<restrict::core_window_t*>(wd)) == false);
 	}
 
+	bool is_window(window wd)
+	{
+		return restrict::window_manager.available(reinterpret_cast<restrict::core_window_t*>(wd));
+	}
+
 	void enable_dropfiles(window wd, bool enb)
 	{
 		internal_scope_guard lock;
@@ -569,6 +574,27 @@ namespace API
 		return false;
 	}
 
+	void draw_through(window wd, std::function<void()> draw_fn)
+	{
+		auto iwd = reinterpret_cast<restrict::core_window_t*>(wd);
+		internal_scope_guard lock;
+		if (!restrict::bedrock.wd_manager.available(iwd))
+			throw std::invalid_argument("draw_through: invalid window parameter");
+
+		if (::nana::category::flags::root != iwd->other.category)
+			throw std::invalid_argument("draw_through: the window is not a root widget");
+
+		iwd->other.attribute.root->draw_through.swap(draw_fn);
+	}
+
+	void map_through_widgets(window wd, native_drawable_type drawable)
+	{
+		auto iwd = reinterpret_cast<::nana::detail::basic_window*>(wd);
+		internal_scope_guard lock;
+		if (restrict::bedrock.wd_manager.available(iwd) && iwd->is_draw_through() )
+			restrict::bedrock.map_through_widgets(iwd, drawable);
+	}
+
 	nana::size window_size(window wd)
 	{
 		nana::rectangle r;