a_group_impl.cpp

#include <nana/gui/wvl.hpp>
#include <nana/gui/place.hpp>
#include <nana/gui/widgets/button.hpp>
#include <nana/gui/widgets/panel.hpp>
#include <nana/gui/widgets/form.hpp>
#include <nana/gui/widgets/label.hpp>
#include <nana/gui/drawing.hpp>

using namespace nana;
namespace dm
{
    class group
	    : public panel<true>
    {
    public:
	    template<typename T, typename ...Args>
	    T* create_widget(Args&&... args)
	    {
		    widgets_.emplace_back(new T(*this, std::forward<Args>(args)...)); // warning C4800: 'const wchar_t *': forcing value to bool 'true' or 'false'  

		    plc_["abc"] << widgets_.back()->handle();
		    plc_.collocate();
		    return static_cast<T*>(widgets_.back().get());
	    }
    private:
	    void _m_complete_creation() override
	    {
		    //define an etiquete
		    plc_.bind(*this);
		    plc_.div("abc vert gap=5 margin=3");

		    //draw a simple border.
		    drawing dw(*this);
		    dw.draw([](paint::graphics& graph)
		    {
			    graph.rectangle(false, colors::gray_border);
		    });
	    }
    private:
	    place plc_;
	    std::vector<std::unique_ptr<widget>> widgets_;
    };

    class group1: public panel<true>
    {
    public:
        place           plc   {*this};
        label           titel/*  {*this}*/;
        std::string     fmt;

        group1 ( widget &owner, 
                 std::string titel_={}, 
                 bool format=false, 
                 unsigned gap=2, 
                 rectangle r={})
        : panel (owner, r),
          titel (*this, titel_)
        {
            titel.format(format);
            nana::size sz = titel.measure(1000);
            std::stringstream ft;

            ft << "vertical margin=[0," << gap << "," << gap << "," << gap << "]"
               << " <weight=" << sz.height << " <weight=5> <titel weight=" << sz.width+1 << "> >";
            fmt = ft.str();

            plc["titel"] << titel;

            color obg = owner.bgcolor();
            titel.bgcolor(obg.blend(colors::black, 0.975) );
            color bg=obg.blend(colors::black, 0.950 );
            bgcolor(bg);

            drawing dw(*this);
		    dw.draw([gap,sz,bg,obg](paint::graphics& graph)
		    {
			    graph.rectangle(true, obg);
                graph.round_rectangle(rectangle(       point ( gap-1,   sz.height/2), 
                                                 nana::size  (graph.width()-2*(gap-1),   graph.height()-sz.height/2-(gap-1))),
                                      3,3, colors::gray_border,     true, bg);
           });

           plc.div(fmt.c_str());
        }
    };

}

int main()
{

	form fm;
    fm.bgcolor(colors::mint_cream );
    place plc(fm);


	dm::group grp;
	grp.create(fm );
    grp.create_widget<label>("Group:");

    plc["left_field"] << grp;

    dm::group1 grp_1(fm, "A new <bold=true, color=0xff0000, font=\"Consolas\">Group:</>", true );
    label lab{grp_1, "A label "};
    button b1{grp_1, "add button"};
    button b2{grp_1, "button2"};
    button b3{grp_1, "button3"};
    grp_1.fmt += "<vertical margin=2 gap= 2 <lab> | 70% < <left_field> | 70% <right_field>> >";
    grp_1.plc["lab"] << lab.text_align(align::right)  ;
    grp_1.plc["left_field"] << b1  ;
    grp_1.plc["right_field"] << b2 << b3;
    grp_1.plc.div(grp_1.fmt.c_str());
    //grp1.plc.collocate();    // problem !!!!!!!!!!!!!!

    plc["right_field"] << grp_1;
    plc.div("horizontal gap=3 margin=30  < <left_field> | 70% <right_field>> ");
    plc.collocate();
    grp_1.plc.collocate();    // OK

	b1.events().click([&grp]
	{
		auto p = grp.create_widget<button>();
		p->caption("Button");
	});

	fm.show();

	::nana::exec();
}
///