// Generate is just like New, but generates a new X resource id for you.
// Geom is initialized to (0, 0) 1x1.
// It is possible for id generation to return an error, in which case, an
// error is returned here.
func Generate(xu *xgbutil.XUtil) (*Window, error) {
	wid, err := xproto.NewWindowId(xu.Conn())
	if err != nil {
		return nil, err
	}
	return New(xu, wid), nil
}

func (w *windower) NewWindow() *Window {
	win, err := xproto.NewWindowId(w.conn)
	if err != nil {
		return nil
	}
	return &Window{w.conn, win, w.root, 0, 0}
}

// Replace existing window manager
func usurpWM(X *xgb.Conn, screen *xproto.ScreenInfo) {
	wmName := fmt.Sprintf("WM_S%d", X.DefaultScreen)
	managerAtom, err := xproto.InternAtom(X, true, uint16(len(wmName)), wmName).Reply()
	if err != nil {
		log.Fatal(err)
	}

	fakeWindow, _ := xproto.NewWindowId(X)
	xproto.CreateWindow(X, // Connection
		screen.RootDepth, // Depth
		fakeWindow,       // Window Id
		screen.Root,      // Parent Window
		-1000, -1000,     // x, y
		1, 1, // width, height
		0, // border_width
		xproto.WindowClassInputOutput, // class
		screen.RootVisual,             // visual
		xproto.CwEventMask|xproto.CwOverrideRedirect,
		[]uint32{1, xproto.EventMaskPropertyChange}) // masks
	xproto.MapWindow(X, fakeWindow)
	err = xproto.SetSelectionOwnerChecked(X, fakeWindow, managerAtom.Atom, xproto.TimeCurrentTime).Check()
	if err != nil {
		log.Fatal(err)
	}
}

func (s *screenImpl) initWindow32() error {
	visualid, err := findVisual(s.xsi, 32)
	if err != nil {
		return err
	}
	colormap, err := xproto.NewColormapId(s.xc)
	if err != nil {
		return fmt.Errorf("x11driver: xproto.NewColormapId failed: %v", err)
	}
	if err := xproto.CreateColormapChecked(
		s.xc, xproto.ColormapAllocNone, colormap, s.xsi.Root, visualid).Check(); err != nil {
		return fmt.Errorf("x11driver: xproto.CreateColormap failed: %v", err)
	}
	s.window32, err = xproto.NewWindowId(s.xc)
	if err != nil {
		return fmt.Errorf("x11driver: xproto.NewWindowId failed: %v", err)
	}
	s.gcontext32, err = xproto.NewGcontextId(s.xc)
	if err != nil {
		return fmt.Errorf("x11driver: xproto.NewGcontextId failed: %v", err)
	}
	const depth = 32
	xproto.CreateWindow(s.xc, depth, s.window32, s.xsi.Root,
		0, 0, 1, 1, 0,
		xproto.WindowClassInputOutput, visualid,
		// The CwBorderPixel attribute seems necessary for depth == 32. See
		// http://stackoverflow.com/questions/3645632/how-to-create-a-window-with-a-bit-depth-of-32
		xproto.CwBorderPixel|xproto.CwColormap,
		[]uint32{0, uint32(colormap)},
	)
	xproto.CreateGC(s.xc, s.gcontext32, xproto.Drawable(s.window32), 0, nil)
	return nil
}

func createWindow() xproto.Window {
	wid, err := xproto.NewWindowId(X.Conn())
	if err != nil {
		log.Fatal(err)
	}
	scrn := X.Screen()

	xproto.CreateWindow(X.Conn(), scrn.RootDepth, wid, X.RootWin(),
		0, 0, 400, 400, 0,
		xproto.WindowClassInputOutput, scrn.RootVisual, 0, []uint32{})

	return wid
}

func start_server(c *xgb.Conn, s *xproto.ScreenInfo, rl_execute_atom xproto.Atom) {
	win, err := xproto.NewWindowId(c)
	if err != nil {
		panic(err)
	}

	// Make a window which can be communicated with
	err = xproto.CreateWindowChecked(c, s.RootDepth, win, s.Root, 0, 0, 1, 1, 0, 0, 0, 0, nil).Check()
	if err != nil {
		panic(err)
	}

	err = xproto.ChangePropertyChecked(c, xproto.PropModeReplace, win,
		rl_execute_atom, xproto.AtomString, 8, xproto.PropModeReplace,
		[]byte("\x00")).Check()
	if err != nil {
		panic(err)
	}
	err = xproto.ChangeWindowAttributesChecked(c, win, xproto.CwEventMask, []uint32{xproto.EventMaskPropertyChange}).Check()
	if err != nil {
		panic(err)
	}

	get_execute_value := func() string {
		response, err := xproto.GetProperty(c, false, win, rl_execute_atom,
			xproto.GetPropertyTypeAny, 0, 1024).Reply()
		if err != nil {
			panic(err)
		}
		result := string(response.Value)
		return result
	}

	log.Print("Ready and waiting..")
	// Event loop
	for {
		reply, err := c.WaitForEvent()
		if err != nil {
			log.Panic("Error in event loop:", err)
		}

		switch event := reply.(type) {
		case xproto.PropertyNotifyEvent:
			if event.Window == win && event.Atom == rl_execute_atom {
				values := strings.Split(get_execute_value(), "\x00")
				run(values)
			}
		}
	}
}

func Open(c *xgb.Conn, ctx, title, text string) (*Window, error) {
	gc, ok := ctxs[ctx]
	if !ok {
		return nil, BadContextError(ctx)
	}

	scr := xproto.Setup(c).DefaultScreen(c)
	wdwid, err := xproto.NewWindowId(c)
	if err != nil {
		return nil, err
	}

	lines := cutLines(c, gc.width-2*gc.border, gc.font, text)
	height := uint32(len(lines)) * gc.fontHeight

	var mask uint32 = xproto.CwBackPixel | xproto.CwOverrideRedirect | xproto.CwEventMask
	values := make([]uint32, 3)
	values[0] = scr.WhitePixel
	values[1] = 1
	values[2] = xproto.EventMaskExposure
	err = xproto.CreateWindowChecked(c, xproto.WindowClassCopyFromParent, wdwid, scr.Root,
		0, 0, uint16(gc.width), uint16(height+2*gc.border), 1,
		xproto.WindowClassInputOutput, scr.RootVisual,
		mask, values).Check()
	if err != nil {
		return nil, err
	}
	xproto.ChangeProperty(c, xproto.PropModeReplace, wdwid,
		xproto.AtomWmName, xproto.AtomString,
		8, uint32(len(title)), []byte(title))

	var wdw Window
	wdw.id = wdwid
	wdw.conn = c
	wdw.lines = lines
	wdw.gc = gc
	wdw.geom = types.Geometry{0, 0, int32(gc.width), int32(height + 2*gc.border)}
	return &wdw, nil
}

func default1() {

	X, err := xgb.NewConn()
	if err != nil {
		fmt.Println(err)
		return
	}

	wid, _ := xproto.NewWindowId(X)
	screen := xproto.Setup(X).DefaultScreen(X)
	xproto.CreateWindow(X, screen.RootDepth, wid, screen.Root,
		0, 0, 500, 500, 0,
		xproto.WindowClassInputOutput, screen.RootVisual,
		xproto.CwBackPixel|xproto.CwEventMask,
		[]uint32{
			0xffffffff,
			xproto.EventMaskStructureNotify |
				xproto.EventMaskKeyPress |
				xproto.EventMaskKeyRelease})

	xproto.MapWindow(X, wid)
	for {
		ev, xerr := X.WaitForEvent()
		if ev == nil && xerr == nil {
			fmt.Println("Both event and error are nil. Exiting...")
			return
		}

		if ev != nil {
			fmt.Println("Event: %s\r\n", ev)
		}
		if xerr != nil {
			fmt.Println("Error: %s\r\n", xerr)
		}

	}

}

func mkMotion(s *xproto.ScreenInfo, c *xgb.Conn) (xproto.Window, error) {
	motion, err := xproto.NewWindowId(c)
	if err != nil {
		return motion, err
	}
	xproto.CreateWindow(
		c,
		s.RootDepth,
		motion,
		s.Root,
		0,
		0,
		s.WidthInPixels,
		s.HeightInPixels,
		0,
		xproto.WindowClassInputOnly,
		s.RootVisual,
		xproto.CwEventMask,
		[]uint32{xproto.EventMaskPointerMotion},
	)
	xproto.MapWindow(c, motion)
	return motion, nil
}

func mkMeta(s *xproto.ScreenInfo, c *xgb.Conn) (xproto.Window, error) {
	meta, err := xproto.NewWindowId(c)
	if err != nil {
		return meta, err
	}

	xproto.CreateWindow(
		c,
		s.RootDepth,
		meta,
		s.Root,
		-1,
		-1,
		1,
		1,
		0,
		xproto.WindowClassInputOnly,
		s.RootVisual,
		0,          //xproto.CwEventMask|xproto.CwOverrideRedirect,
		[]uint32{}, //nil, //[]uint32{1, xproto.EventMaskPropertyChange},
	)
	xproto.MapWindow(c, meta)
	return meta, nil
}

func main() {
	// Open the connection to the X server
	X, err := xgb.NewConn()
	if err != nil {
		log.Fatal(err)
	}
	defer X.Close()

	// geometric objects
	points := []xproto.Point{
		{10, 10},
		{10, 20},
		{20, 10},
		{20, 20}}

	polyline := []xproto.Point{
		{50, 10},
		{5, 20}, // rest of points are relative
		{25, -20},
		{10, 10}}

	segments := []xproto.Segment{
		{100, 10, 140, 30},
		{110, 25, 130, 60}}

	rectangles := []xproto.Rectangle{
		{10, 50, 40, 20},
		{80, 50, 10, 40}}

	arcs := []xproto.Arc{
		{10, 100, 60, 40, 0, 90 << 6},
		{90, 100, 55, 40, 0, 270 << 6}}

	setup := xproto.Setup(X)
	// Get the first screen
	screen := setup.DefaultScreen(X)

	// Create black (foreground) graphic context
	foreground, _ := xproto.NewGcontextId(X)
	mask := uint32(xproto.GcForeground | xproto.GcGraphicsExposures)
	values := []uint32{screen.BlackPixel, 0}
	xproto.CreateGC(X, foreground, xproto.Drawable(screen.Root), mask, values)

	// Ask for our window's Id
	win, _ := xproto.NewWindowId(X)
	winDrawable := xproto.Drawable(win)

	// Create the window
	mask = uint32(xproto.CwBackPixel | xproto.CwEventMask)
	values = []uint32{screen.WhitePixel, xproto.EventMaskExposure}
	xproto.CreateWindow(X, // Connection
		screen.RootDepth, // Depth
		win,              // Window Id
		screen.Root,      // Parent Window
		0, 0,             // x, y
		150, 150, // width, height
		10, // border_width
		xproto.WindowClassInputOutput, // class
		screen.RootVisual,             // visual
		mask, values)                  // masks

	// Map the window on the screen
	xproto.MapWindow(X, win)

	// Obey the window-delete protocol
	tp := "WM_PROTOCOLS"
	prp := "WM_DELETE_WINDOW"
	typeAtom, _ := xproto.InternAtom(X, true, uint16(len(tp)), tp).Reply()
	propertyAtom, _ := xproto.InternAtom(X, true, uint16(len(prp)), prp).Reply()

	// It turns out that we need the window ID as a byte-stream... WTF!!
	// xprop.ChangeProp(xu, win, 8, "WM_NAME", "STRING", ([]byte)(name))
	// ChangeProp(xu *xgbutil.XUtil, win xproto.Window, format byte, prop string, typ string, data []byte)
	data := make([]byte, 4)
	xgb.Put32(data, uint32(propertyAtom.Atom))
	xproto.ChangeProperty(X, xproto.PropModeReplace, win, typeAtom.Atom, xproto.AtomAtom, 32, 1, data)

	for {
		evt, err := X.WaitForEvent()
		fmt.Printf("An event of type %T occured.\n", evt)

		if evt == nil && err == nil {
			fmt.Println("Exiting....")
			return
		} else if err != nil {
			log.Fatal(err)
		}

		switch event := evt.(type) {
		case xproto.ExposeEvent:
			/* We draw the points */
			xproto.PolyPoint(X, xproto.CoordModeOrigin, winDrawable, foreground, points)

			/* We draw the polygonal line */
			xproto.PolyLine(X, xproto.CoordModePrevious, winDrawable, foreground, polyline)

			/* We draw the segments */
			xproto.PolySegment(X, winDrawable, foreground, segments)

			/* We draw the rectangles */
//.........这里部分代码省略.........

func (s *screenImpl) NewWindow(opts *screen.NewWindowOptions) (screen.Window, error) {
	// TODO: look at opts.
	const width, height = 1024, 768

	xw, err := xproto.NewWindowId(s.xc)
	if err != nil {
		return nil, fmt.Errorf("x11driver: xproto.NewWindowId failed: %v", err)
	}
	xg, err := xproto.NewGcontextId(s.xc)
	if err != nil {
		return nil, fmt.Errorf("x11driver: xproto.NewGcontextId failed: %v", err)
	}
	xp, err := render.NewPictureId(s.xc)
	if err != nil {
		return nil, fmt.Errorf("x11driver: render.NewPictureId failed: %v", err)
	}
	pictformat := render.Pictformat(0)
	switch s.xsi.RootDepth {
	default:
		return nil, fmt.Errorf("x11driver: unsupported root depth %d", s.xsi.RootDepth)
	case 24:
		pictformat = s.pictformat24
	case 32:
		pictformat = s.pictformat32
	}

	w := &windowImpl{
		s:       s,
		xw:      xw,
		xg:      xg,
		xp:      xp,
		pump:    pump.Make(),
		xevents: make(chan xgb.Event),
	}

	s.mu.Lock()
	s.windows[xw] = w
	s.mu.Unlock()

	xproto.CreateWindow(s.xc, s.xsi.RootDepth, xw, s.xsi.Root,
		0, 0, width, height, 0,
		xproto.WindowClassInputOutput, s.xsi.RootVisual,
		xproto.CwEventMask,
		[]uint32{0 |
			xproto.EventMaskKeyPress |
			xproto.EventMaskKeyRelease |
			xproto.EventMaskButtonPress |
			xproto.EventMaskButtonRelease |
			xproto.EventMaskPointerMotion |
			xproto.EventMaskExposure |
			xproto.EventMaskStructureNotify |
			xproto.EventMaskFocusChange,
		},
	)
	s.setProperty(xw, s.atomWMProtocols, s.atomWMDeleteWindow, s.atomWMTakeFocus)
	xproto.CreateGC(s.xc, xg, xproto.Drawable(xw), 0, nil)
	render.CreatePicture(s.xc, xp, xproto.Drawable(xw), pictformat, 0, nil)
	xproto.MapWindow(s.xc, xw)

	return w, nil
}

func main() {
	X, err := xgb.NewConn()
	if err != nil {
		fmt.Println(err)
		return
	}

	wid, _ := xproto.NewWindowId(X)
	screen := xproto.Setup(X).DefaultScreen(X)
	xproto.CreateWindow(X, screen.RootDepth, wid, screen.Root,
		0, 0, 240, 240, 0,
		xproto.WindowClassInputOutput,
		screen.RootVisual,
		xproto.CwBackPixel|xproto.CwEventMask,
		[]uint32{ // values must be in the order defined by the protocol
			0xffffffff,
			xproto.EventMaskStructureNotify |
				xproto.EventMaskKeyPress |
				xproto.EventMaskKeyRelease})

	xproto.MapWindow(X, wid)
	fmt.Printf("%d %d\n", screen.AllowedDepths[0].Visuals[0].VisualId, screen.RootVisual)

	var (
		ux, uy float64 = 1, 1

		fe                   cairo.FontExtents
		te                   cairo.TextExtents
		text                 = "joy"
		x, y, px, dashlength float64
	)

	surface := cairo.NewSurfaceFromXCB(xproto.Drawable(wid), screen.AllowedDepths[0].Visuals[0], 240, 240)
	surface.Scale(240, 240)
	surface.SetFontSize(0.5)

	/* Drawing code goes here */
	surface.SetSourceRGB(0.0, 0.0, 0.0)
	surface.SelectFontFace("Georgia", cairo.FONT_SLANT_NORMAL, cairo.FONT_WEIGHT_BOLD)
	surface.FontExtents(&fe)

	ux, uy = surface.DeviceToUserDistance(ux, uy)
	if ux > uy {
		px = ux
	} else {
		px = uy
	}

	surface.FontExtents(&fe)
	surface.TextExtents(text, &te)
	x = 0.5 - te.X_bearing - te.Width/2
	y = 0.5 - fe.Descent + fe.Height/2

	/* baseline, descent, ascent, height */
	surface.SetLineWidth(4 * px)
	dashlength = 9 * px
	surface.SetDash([]float64{dashlength}, 0)
	surface.SetSourceRGBA(0, 0.6, 0, 0.5)
	surface.MoveTo(x+te.X_bearing, y)
	surface.RelLineTo(te.Width, 0)
	surface.MoveTo(x+te.X_bearing, y+fe.Descent)
	surface.RelLineTo(te.Width, 0)
	surface.MoveTo(x+te.X_bearing, y-fe.Ascent)
	surface.RelLineTo(te.Width, 0)
	surface.MoveTo(x+te.X_bearing, y-fe.Height)
	surface.RelLineTo(te.Width, 0)
	surface.Stroke()

	/* extents: width & height */
	surface.SetSourceRGBA(0, 0, 0.75, 0.5)
	surface.SetLineWidth(px)
	dashlength = 3 * px
	surface.SetDash([]float64{dashlength}, 0)
	surface.Rectangle(x+te.X_bearing, y+te.Y_bearing, te.Width, te.Height)
	surface.Stroke()

	/* text */
	surface.MoveTo(x, y)
	surface.SetSourceRGB(0, 0, 0)
	surface.ShowText(text)

	/* bearing */
	surface.SetDash(nil, 0)
	surface.SetLineWidth(2 * px)
	surface.SetSourceRGBA(0, 0, 0.75, 0.5)
	surface.MoveTo(x, y)
	surface.RelLineTo(te.X_bearing, te.Y_bearing)
	surface.Stroke()

	/* text's advance */
	surface.SetSourceRGBA(0, 0, 0.75, 0.5)
	surface.Arc(x+te.X_advance, y+te.Y_advance, 5*px, 0, 2*math.Pi)
	surface.Fill()

	/* reference point */
	surface.Arc(x, y, 5*px, 0, 2*math.Pi)
	surface.SetSourceRGBA(0.75, 0, 0, 0.5)
	surface.Fill()

	surface.Finish()
//.........这里部分代码省略.........

func main() {
	// Open the connection to the X server
	X, err := xgb.NewConn()
	if err != nil {
		log.Fatal(err)
	}
	defer X.Close()

	setup := xproto.Setup(X)
	// Get the first screen
	screen := setup.DefaultScreen(X)

	// Replace existing window manager
	wmName := fmt.Sprintf("WM_S%d", X.DefaultScreen)
	managerAtom, err := xproto.InternAtom(X, true, uint16(len(wmName)), wmName).Reply()
	if err != nil {
		log.Fatal(err)
	}

	fakeWindow, _ := xproto.NewWindowId(X)
	xproto.CreateWindow(X, // Connection
		screen.RootDepth, // Depth
		fakeWindow,       // Window Id
		screen.Root,      // Parent Window
		-1000, -1000,     // x, y
		1, 1, // width, height
		0, // border_width
		xproto.WindowClassInputOutput, // class
		screen.RootVisual,             // visual
		xproto.CwEventMask|xproto.CwOverrideRedirect,
		[]uint32{1, xproto.EventMaskPropertyChange}) // masks
	xproto.MapWindow(X, fakeWindow)
	err = xproto.SetSelectionOwnerChecked(X, fakeWindow, managerAtom.Atom, xproto.TimeCurrentTime).Check()
	if err != nil {
		fmt.Println("foo")
		log.Fatal(err)
	}

	arcs := []xproto.Arc{
		{10, 100, 60, 40, 0, 90 << 6},
		{90, 100, 55, 40, 0, 270 << 6}}

	// Create black (foreground) graphic context
	foreground, _ := xproto.NewGcontextId(X)
	mask := uint32(xproto.GcForeground | xproto.GcGraphicsExposures)
	values := []uint32{screen.BlackPixel, 0}
	xproto.CreateGC(X, foreground, xproto.Drawable(screen.Root), mask, values)

	// Ask for our window's Id
	win, _ := xproto.NewWindowId(X)
	winDrawable := xproto.Drawable(win)

	// Create the window
	mask = uint32(xproto.CwBackPixel | xproto.CwEventMask)
	values = []uint32{screen.WhitePixel, xproto.EventMaskExposure}
	xproto.CreateWindow(X, // Connection
		screen.RootDepth, // Depth
		win,              // Window Id
		screen.Root,      // Parent Window
		0, 0,             // x, y
		150, 150, // width, height
		10, // border_width
		xproto.WindowClassInputOutput, // class
		screen.RootVisual,             // visual
		mask, values)                  // masks

	// Map the window on the screen
	xproto.MapWindow(X, win)

	// Obey the window-delete protocol
	tp := "WM_PROTOCOLS"
	prp := "WM_DELETE_WINDOW"
	typeAtom, _ := xproto.InternAtom(X, true, uint16(len(tp)), tp).Reply()
	propertyAtom, _ := xproto.InternAtom(X, true, uint16(len(prp)), prp).Reply()

	data := make([]byte, 4)
	xgb.Put32(data, uint32(propertyAtom.Atom))
	xproto.ChangeProperty(X, xproto.PropModeReplace, win, typeAtom.Atom, xproto.AtomAtom, 32, 1, data)

	// Main loop
	for {
		evt, err := X.WaitForEvent()
		fmt.Printf("An event of type %T occured.\n", evt)

		if evt == nil && err == nil {
			fmt.Println("Exiting....")
			return
		} else if err != nil {
			log.Fatal(err)
		}

		switch event := evt.(type) {
		case xproto.ExposeEvent:
			/* We draw the arcs */
			xproto.PolyArc(X, winDrawable, foreground, arcs)
		case xproto.ClientMessageEvent:
			if len(event.Data.Data32) > 0 {
				data := xproto.Atom(event.Data.Data32[0])
				if data == propertyAtom.Atom {
					return
//.........这里部分代码省略.........

func initDesktop(xScreen *xp.ScreenInfo) {
	xFont, err := xp.NewFontId(xConn)
	if err != nil {
		log.Fatal(err)
	}
	xCursor, err := xp.NewCursorId(xConn)
	if err != nil {
		log.Fatal(err)
	}
	err = xp.OpenFontChecked(xConn, xFont, uint16(len("cursor")), "cursor").Check()
	if err != nil {
		log.Fatal(err)
	}
	const xcLeftPtr = 68 // XC_left_ptr from cursorfont.h.
	err = xp.CreateGlyphCursorChecked(
		xConn, xCursor, xFont, xFont, xcLeftPtr, xcLeftPtr+1,
		0xffff, 0xffff, 0xffff, 0, 0, 0).Check()
	if err != nil {
		log.Fatal(err)
	}
	err = xp.CloseFontChecked(xConn, xFont).Check()
	if err != nil {
		log.Fatal(err)
	}

	desktopXWin, err = xp.NewWindowId(xConn)
	if err != nil {
		log.Fatal(err)
	}
	desktopXGC, err = xp.NewGcontextId(xConn)
	if err != nil {
		log.Fatal(err)
	}
	desktopWidth = xScreen.WidthInPixels
	desktopHeight = xScreen.HeightInPixels

	if err := xp.CreateWindowChecked(
		xConn, xScreen.RootDepth, desktopXWin, xScreen.Root,
		0, 0, desktopWidth, desktopHeight, 0,
		xp.WindowClassInputOutput,
		xScreen.RootVisual,
		xp.CwOverrideRedirect|xp.CwEventMask,
		[]uint32{
			1,
			xp.EventMaskExposure,
		},
	).Check(); err != nil {
		log.Fatal(err)
	}

	if len(xSettings) != 0 {
		initXSettings()
	}

	if err := xp.ConfigureWindowChecked(
		xConn,
		desktopXWin,
		xp.ConfigWindowStackMode,
		[]uint32{
			xp.StackModeBelow,
		},
	).Check(); err != nil {
		log.Fatal(err)
	}

	if err := xp.ChangeWindowAttributesChecked(
		xConn,
		desktopXWin,
		xp.CwBackPixel|xp.CwCursor,
		[]uint32{
			xScreen.BlackPixel,
			uint32(xCursor),
		},
	).Check(); err != nil {
		log.Fatal(err)
	}

	if err := xp.CreateGCChecked(
		xConn,
		desktopXGC,
		xp.Drawable(xScreen.Root),
		0,
		nil,
	).Check(); err != nil {
		log.Fatal(err)
	}

	if err := xp.MapWindowChecked(xConn, desktopXWin).Check(); err != nil {
		log.Fatal(err)
	}
}

// NewConnXgb use the specific xgb.Conn to create a new XUtil.
//
//  NewConn, NewConnDisplay are wrapper of this function.
func NewConnXgb(c *xgb.Conn) (*XUtil, error) {
	setup := xproto.Setup(c)
	screen := setup.DefaultScreen(c)

	// Initialize our central struct that stores everything.
	xu := &XUtil{
		conn:             c,
		Quit:             false,
		Evqueue:          make([]EventOrError, 0, 1000),
		EvqueueLck:       &sync.RWMutex{},
		setup:            setup,
		screen:           screen,
		root:             screen.Root,
		eventTime:        xproto.Timestamp(0), // last event time
		Atoms:            make(map[string]xproto.Atom, 50),
		AtomsLck:         &sync.RWMutex{},
		AtomNames:        make(map[xproto.Atom]string, 50),
		AtomNamesLck:     &sync.RWMutex{},
		Callbacks:        make(map[int]map[xproto.Window][]Callback, 33),
		CallbacksLck:     &sync.RWMutex{},
		Hooks:            make([]CallbackHook, 0),
		HooksLck:         &sync.RWMutex{},
		Keymap:           nil, // we don't have anything yet
		Modmap:           nil,
		KeyRedirect:      0,
		Keybinds:         make(map[KeyKey][]CallbackKey, 10),
		KeybindsLck:      &sync.RWMutex{},
		Keygrabs:         make(map[KeyKey]int, 10),
		Keystrings:       make([]KeyString, 0, 10),
		Mousebinds:       make(map[MouseKey][]CallbackMouse, 10),
		MousebindsLck:    &sync.RWMutex{},
		Mousegrabs:       make(map[MouseKey]int, 10),
		InMouseDrag:      false,
		MouseDragStepFun: nil,
		MouseDragEndFun:  nil,
		ErrorHandler:     func(err xgb.Error) { Logger.Println(err) },
	}

	var err error = nil
	// Create a general purpose graphics context
	xu.gc, err = xproto.NewGcontextId(xu.conn)
	if err != nil {
		return nil, err
	}
	xproto.CreateGC(xu.conn, xu.gc, xproto.Drawable(xu.root),
		xproto.GcForeground, []uint32{xu.screen.WhitePixel})

	// Create a dummy window
	xu.dummy, err = xproto.NewWindowId(xu.conn)
	if err != nil {
		return nil, err
	}
	xproto.CreateWindow(xu.conn, xu.Screen().RootDepth, xu.dummy, xu.RootWin(),
		-1000, -1000, 1, 1, 0,
		xproto.WindowClassInputOutput, xu.Screen().RootVisual,
		xproto.CwEventMask|xproto.CwOverrideRedirect,
		[]uint32{1, xproto.EventMaskPropertyChange})
	xproto.MapWindow(xu.conn, xu.dummy)

	// Register the Xinerama extension... because it doesn't cost much.
	err = xinerama.Init(xu.conn)

	// If we can't register Xinerama, that's okay. Output something
	// and move on.
	if err != nil {
		Logger.Printf("WARNING: %s\n", err)
		Logger.Printf("MESSAGE: The 'xinerama' package cannot be used " +
			"because the XINERAMA extension could not be loaded.")
	}

	return xu, nil
}

func main() {
	X, err := xgb.NewConn()
	if err != nil {
		fmt.Println(err)
		return
	}

	// xproto.Setup retrieves the Setup information from the setup bytes
	// gathered during connection.
	setup := xproto.Setup(X)

	// This is the default screen with all its associated info.
	screen := setup.DefaultScreen(X)

	// Any time a new resource (i.e., a window, pixmap, graphics context, etc.)
	// is created, we need to generate a resource identifier.
	// If the resource is a window, then use xproto.NewWindowId. If it's for
	// a pixmap, then use xproto.NewPixmapId. And so on...
	wid, _ := xproto.NewWindowId(X)

	// CreateWindow takes a boatload of parameters.
	xproto.CreateWindow(X, screen.RootDepth, wid, screen.Root,
		0, 0, 500, 500, 0,
		xproto.WindowClassInputOutput, screen.RootVisual, 0, []uint32{})

	// This call to ChangeWindowAttributes could be factored out and
	// included with the above CreateWindow call, but it is left here for
	// instructive purposes. It tells X to send us events when the 'structure'
	// of the window is changed (i.e., when it is resized, mapped, unmapped,
	// etc.) and when a key press or a key release has been made when the
	// window has focus.
	// We also set the 'BackPixel' to white so that the window isn't butt ugly.
	xproto.ChangeWindowAttributes(X, wid,
		xproto.CwBackPixel|xproto.CwEventMask,
		[]uint32{ // values must be in the order defined by the protocol
			0xffffffff,
			xproto.EventMaskStructureNotify |
				xproto.EventMaskKeyPress |
				xproto.EventMaskKeyRelease})

	// MapWindow makes the window we've created appear on the screen.
	// We demonstrated the use of a 'checked' request here.
	// A checked request is a fancy way of saying, "do error handling
	// synchronously." Namely, if there is a problem with the MapWindow request,
	// we'll get the error *here*. If we were to do a normal unchecked
	// request (like the above CreateWindow and ChangeWindowAttributes
	// requests), then we would only see the error arrive in the main event
	// loop.
	//
	// Typically, checked requests are useful when you need to make sure they
	// succeed. Since they are synchronous, they incur a round trip cost before
	// the program can continue, but this is only going to be noticeable if
	// you're issuing tons of requests in succession.
	//
	// Note that requests without replies are by default unchecked while
	// requests *with* replies are checked by default.
	err = xproto.MapWindowChecked(X, wid).Check()
	if err != nil {
		fmt.Printf("Checked Error for mapping window %d: %s\n", wid, err)
	} else {
		fmt.Printf("Map window %d successful!\n", wid)
	}

	// This is an example of an invalid MapWindow request and what an error
	// looks like.
	err = xproto.MapWindowChecked(X, 0).Check()
	if err != nil {
		fmt.Printf("Checked Error for mapping window 0x1: %s\n", err)
	} else { // neva
		fmt.Printf("Map window 0x1 successful!\n")
	}

	// Start the main event loop.
	for {
		// WaitForEvent either returns an event or an error and never both.
		// If both are nil, then something went wrong and the loop should be
		// halted.
		//
		// An error can only be seen here as a response to an unchecked
		// request.
		ev, xerr := X.WaitForEvent()
		if ev == nil && xerr == nil {
			fmt.Println("Both event and error are nil. Exiting...")
			return
		}

		if ev != nil {
			fmt.Printf("Event: %s\n", ev)
		}
		if xerr != nil {
			fmt.Printf("Error: %s\n", xerr)
		}
	}
}

func main() {
	// Open the connection to the X server
	X, err := xgb.NewConn()
	if err != nil {
		log.Fatal(err)
	}

	// geometric objects
	points := []xproto.Point{
		{10, 10},
		{10, 20},
		{20, 10},
		{20, 20}}

	polyline := []xproto.Point{
		{50, 10},
		{5, 20}, // rest of points are relative
		{25, -20},
		{10, 10}}

	segments := []xproto.Segment{
		{100, 10, 140, 30},
		{110, 25, 130, 60}}

	rectangles := []xproto.Rectangle{
		{10, 50, 40, 20},
		{80, 50, 10, 40}}

	arcs := []xproto.Arc{
		{10, 100, 60, 40, 0, 90 << 6},
		{90, 100, 55, 40, 0, 270 << 6}}

	setup := xproto.Setup(X)
	// Get the first screen
	screen := setup.DefaultScreen(X)

	// Create black (foreground) graphic context
	foreground, _ := xproto.NewGcontextId(X)
	mask := uint32(xproto.GcForeground | xproto.GcGraphicsExposures)
	values := []uint32{screen.BlackPixel, 0}
	xproto.CreateGC(X, foreground, xproto.Drawable(screen.Root), mask, values)

	// Ask for our window's Id
	win, _ := xproto.NewWindowId(X)
	winDrawable := xproto.Drawable(win)

	// Create the window
	mask = uint32(xproto.CwBackPixel | xproto.CwEventMask)
	values = []uint32{screen.WhitePixel, xproto.EventMaskExposure}
	xproto.CreateWindow(X, // Connection
		screen.RootDepth, // Depth
		win,              // Window Id
		screen.Root,      // Parent Window
		0, 0,             // x, y
		150, 150, // width, height
		10, // border_width
		xproto.WindowClassInputOutput, // class
		screen.RootVisual,             // visual
		mask, values)                  // masks

	// Map the window on the screen
	xproto.MapWindow(X, win)

	for {
		evt, err := X.WaitForEvent()
		switch evt.(type) {
		case xproto.ExposeEvent:
			/* We draw the points */
			xproto.PolyPoint(X, xproto.CoordModeOrigin, winDrawable, foreground, points)

			/* We draw the polygonal line */
			xproto.PolyLine(X, xproto.CoordModePrevious, winDrawable, foreground, polyline)

			/* We draw the segments */
			xproto.PolySegment(X, winDrawable, foreground, segments)

			/* We draw the rectangles */
			xproto.PolyRectangle(X, winDrawable, foreground, rectangles)

			/* We draw the arcs */
			xproto.PolyArc(X, winDrawable, foreground, arcs)

		default:
			/* Unknown event type, ignore it */
		}

		if err != nil {
			log.Fatal(err)
		}
	}
	return
}