The Big Programming Thread - Page 556

#define XK_LATIN1
#include<X11/Xlib.h>
#include<X11/keysymdef.h>

namespace xlib{

struct application{
	Display* display{XOpenDisplay(nullptr)};
	Window root_window{XDefaultRootWindow(display)};
	int 
		screen_number{XDefaultScreen(display)},
		depth{XDefaultDepth(display,screen_number)},
		xcoord{0},
		ycoord{0};
	unsigned long 
		black_pixel{XBlackPixel(display,screen_number)},
		white_pixel{XWhitePixel(display,screen_number)},
		border{white_pixel},
		background{black_pixel};
	unsigned int
		width{640},
		heigth{480},
		border_width{4},
		window_class{InputOutput};
	GC gc{XDefaultGC(display,screen_number)};
	Visual* visual{XDefaultVisual(display,screen_number)};
	Window window{
		XCreateSimpleWindow(display,root_window,xcoord,ycoord,width,heigth,border_width,border,background)
	};
	application(){
		XSelectInput(
			display,
			window,
			KeyPressMask|PointerMotionMask
		);
		XSetForeground(display,gc,white_pixel);
		XMapWindow(display,window);
		XFlush(display);
	}
	~application(){
		XUnmapWindow(display,window);
		XDestroyWindow(display,window);
		XCloseDisplay(display);
	}
};

}

xlib::application application;

struct chalkboard
{
	struct not_drawing{};
	struct drawing{};
	using states=seq::sequence<not_drawing,drawing>;
	static constexpr not_drawing initial{};

	struct close{};
	struct toggle_pause{};
	struct mouse_position{int x; int y;};
	using symbols=seq::sequence<close,toggle_pause,mouse_position>;

	bool done{false};

	//transitions
		//syntax: to_state operator()(const from_state&,const symbol&)

	//draw a point
	drawing	
		operator()(const drawing&,const mouse_position& m)
	{ XDrawPoint(application.display,application.window,application.gc,m.x,m.y); }

	template<class state>
	using other_state=seq::element<states,(seq::index<states,state>()+1)%2>;

	//toggle to other state
	template<class state>
	other_state<state>
		operator()(const state&,const toggle_pause&)
	{}

	//notify finished
	template<class state>
	state
		operator()(const state&,const close& c)
	{ done=true; }

	//catch all
	template<class state,class symbol>
	state
		operator()(const state&,const symbol&)
	{}

};

int 
	main(int argc,char** argv)
{
	try{
		fsm::machine<chalkboard> fsm;
		XEvent event;
		do{
			XNextEvent(application.display,&event);
			switch(event.type){
			case KeyPress:
				switch(XLookupKeysym(&event.xkey,0)){
				case XK_q:
					fsm|chalkboard::close{};
					break;
				case XK_p:
					fsm|chalkboard::toggle_pause{};
					break;
				}
			case MotionNotify:
				fsm|chalkboard::mouse_position{event.xmotion.x,event.xmotion.y};
				break;
			}
		}while(!fsm.done);
	}catch(const std::exception& e){
		std::cerr<<e.what()<<std::endl;
	}
}