func (c *Client) newClientState() clientState {
	s := clientState{
		geom:      xrect.New(xrect.Pieces(c.frame.Geom())),
		headGeom:  nil,
		frame:     c.frame,
		maximized: c.maximized,
	}
	if c.workspace.IsVisible() {
		s.headGeom = xrect.New(xrect.Pieces(c.workspace.HeadGeom()))
	}
	return s
}

func (c *Client) maybeInitPlace(presumedWorkspace workspace.Workspacer) {
	// This is a hack. Before a client gets sucked into some layout, we
	// always want to have some floating state to fall back on to. However,
	// by the time we're "allowed" to save the client's state, it will have
	// already been placed in the hands of some layout---which may or may
	// not be floating. So we inject our own state forcefully here.
	defer func() {
		wrk := presumedWorkspace
		if wrk.IsVisible() {
			c.states["last-floating"] = clientState{
				geom:      xrect.New(xrect.Pieces(c.frame.Geom())),
				headGeom:  xrect.New(xrect.Pieces(wrk.HeadGeom())),
				frame:     c.frame,
				maximized: c.maximized,
			}
		}
	}()

	// Any client that isn't normal doesn't get placed.
	// Let it do what it do, baby.
	if c.PrimaryType() != TypeNormal {
		return
	}

	// If it's sticky, let it do what it do.
	if _, ok := presumedWorkspace.(*workspace.Sticky); ok {
		return
	}

	// Transients never get placed.
	if c.transientFor != nil {
		return
	}

	// If a user/program position is specified, do not place.
	if c.nhints.Flags&icccm.SizeHintUSPosition > 0 ||
		c.nhints.Flags&icccm.SizeHintPPosition > 0 {

		return
	}

	// We're good, do a placement unless we're already mapped or on a
	// hidden workspace..
	if !presumedWorkspace.IsVisible() || !c.isAttrsUnmapped() {
		return
	}
	w := presumedWorkspace.(*workspace.Workspace)
	w.LayoutFloater().InitialPlacement(c)
}

func (c *Client) DragMoveBegin(rx, ry, ex, ey int) {
	f := c.frame
	moving := f.MovingState()
	moving.Moving = true
	moving.RootX, moving.RootY = rx, ry

	// call for side-effect; makes sure parent window has a valid geometry
	f.Parent().Geometry()

	// unmax!
	c.EnsureUnmax()

	c.dragGeom = xrect.New(xrect.Pieces(f.Geom()))
}

// Convert takes a source and a destination rect, along with a rect
// in the source's rectangle, and returns a new rect translated into the
// destination rect.
func Convert(rect, src, dest xrect.Rect) xrect.Rect {
	nx, ny, nw, nh := xrect.Pieces(rect)

	rectRatio := func(r xrect.Rect) float64 {
		return float64(r.Width()) / float64(r.Height())
	}
	ratio := rectRatio(dest) / rectRatio(src)

	nx = int(ratio*float64(nx-src.X())) + dest.X()
	ny = int(ratio*float64(ny-src.Y())) + dest.Y()

	// XXX: Allow window scaling as a config option.

	return xrect.New(nx, ny, nw, nh)
}

func (c *Client) DragMoveBegin(rx, ry, ex, ey int) bool {
	if c.IsMaximized() {
		return false
	}

	f := c.frame
	moving := f.MovingState()
	moving.Moving = true
	moving.RootX, moving.RootY = rx, ry

	// call for side-effect; makes sure parent window has a valid geometry
	f.Parent().Geometry()

	c.dragGeom = xrect.New(xrect.Pieces(f.Geom()))
	return true
}

//.........这里部分代码省略.........
	// (ex, ey) is the position of the mouse.
	// We basically split the window into something like a tic-tac-toe board:
	// -------------------------
	// |       |       |       |
	// |   A   |       |   F   |
	// |       |   D   |       |
	// ---------       |--------
	// |       |       |       |
	// |   B   |-------|   G   |
	// |       |       |       |
	// ---------       |--------
	// |       |   E   |       |
	// |   C   |       |   H   |
	// |       |       |       |
	// -------------------------
	// Where A, B, C correspond to 'ex < w / 3'
	// and F, G, H correspond to 'ex > w * 2 / 3'
	// and D and E correspond to 'ex >= w / 3 && ex <= w * 2 / 3'
	// The direction is not only important for assigning which cursor to display
	// (where each of the above blocks gets its own cursor), but it is also
	// important for choosing which parts of the geometry to change.
	// For example, if the mouse is in 'H', then the width and height could
	// be changed, but x and y cannot. Conversely, if the mouse is in 'A',
	// all parts of the geometry can change: x, y, width and height.
	// As one last example, if the mouse is in 'D', only y and height of the
	// window can change.
	if dir == ewmh.Infer {
		if ex < w/3 {
			switch {
			case ey < h/3:
				dir = ewmh.SizeTopLeft
			case ey > h*2/3:
				dir = ewmh.SizeBottomLeft
			default: // ey >= h / 3 && ey <= h * 2 / 3
				dir = ewmh.SizeLeft
			}
		} else if ex > w*2/3 {
			switch {
			case ey < h/3:
				dir = ewmh.SizeTopRight
			case ey > h*2/3:
				dir = ewmh.SizeBottomRight
			default: // ey >= h / 3 && ey <= h * 2 / 3
				dir = ewmh.SizeRight
			}
		} else { // ex >= w / 3 && ex <= w * 2 / 3
			switch {
			case ey < h/2:
				dir = ewmh.SizeTop
			default: // ey >= h / 2
				dir = ewmh.SizeBottom
			}
		}
	}

	// Find the right cursor
	var cursor xproto.Cursor = 0
	switch dir {
	case ewmh.SizeTop:
		cursor = cursors.TopSide
	case ewmh.SizeTopRight:
		cursor = cursors.TopRightCorner
	case ewmh.SizeRight:
		cursor = cursors.RightSide
	case ewmh.SizeBottomRight:
		cursor = cursors.BottomRightCorner
	case ewmh.SizeBottom:
		cursor = cursors.BottomSide
	case ewmh.SizeBottomLeft:
		cursor = cursors.BottomLeftCorner
	case ewmh.SizeLeft:
		cursor = cursors.LeftSide
	case ewmh.SizeTopLeft:
		cursor = cursors.TopLeftCorner
	}

	// Save some state that we'll need when computing a window's new geometry
	resizing.Resizing = true
	resizing.RootX, resizing.RootY = rx, ry
	resizing.X, resizing.Y = f.Geom().X(), f.Geom().Y()
	resizing.Width, resizing.Height = f.Geom().Width(), f.Geom().Height()

	// Our geometry calculations depend upon which direction we're resizing.
	// Namely, the direction determines which parts of the geometry need to
	// be modified. Pre-compute those parts (i.e., x, y, width and/or height)
	resizing.Xs = dir == ewmh.SizeLeft || dir == ewmh.SizeTopLeft ||
		dir == ewmh.SizeBottomLeft
	resizing.Ys = dir == ewmh.SizeTop || dir == ewmh.SizeTopLeft ||
		dir == ewmh.SizeTopRight
	resizing.Ws = dir == ewmh.SizeTopLeft || dir == ewmh.SizeTopRight ||
		dir == ewmh.SizeRight || dir == ewmh.SizeBottomRight ||
		dir == ewmh.SizeBottomLeft || dir == ewmh.SizeLeft
	resizing.Hs = dir == ewmh.SizeTopLeft || dir == ewmh.SizeTop ||
		dir == ewmh.SizeTopRight || dir == ewmh.SizeBottomRight ||
		dir == ewmh.SizeBottom || dir == ewmh.SizeBottomLeft

	c.dragGeom = xrect.New(xrect.Pieces(f.Geom()))

	return true, cursor
}

func (c *Client) maybeInitPlace(presumedWorkspace workspace.Workspacer) {
	// This is a hack. Before a client gets sucked into some layout, we
	// always want to have some floating state to fall back on to. However,
	// by the time we're "allowed" to save the client's state, it will have
	// already been placed in the hands of some layout---which may or may
	// not be floating. So we inject our own state forcefully here.
	defer func() {
		wrk := presumedWorkspace
		if wrk.IsVisible() {
			c.states["last-floating"] = clientState{
				geom:      xrect.New(xrect.Pieces(c.frame.Geom())),
				headGeom:  xrect.New(xrect.Pieces(wrk.HeadGeom())),
				frame:     c.frame,
				maximized: c.maximized,
			}
		} else if wm.Startup {
			// This is a bit tricky. If the window manager is starting up and
			// has to manage existing clients, then we need to find which
			// head the client is on and save its state. This is so future
			// workspace switches will be able to place the client
			// appropriately.
			// (This is most common on a Wingo restart.)
			// We refer to detected workspace as "fake" because the client
			// isn't on a visible workspace (see above), and therefore the
			// visible workspace returned by FindMostOverlap *cannot* contain
			// this client. Therefore, we're only using the fake workspace
			// to get the geometry.
			// (This would make more sense if FindMostOverlap returned a head
			// geometry, but it turns out that a workspace geometry is more
			// useful.)
			cgeom := c.frame.Geom()
			if fakeWrk := wm.Heads.FindMostOverlap(cgeom); fakeWrk != nil {
				c.states["last-floating"] = clientState{
					geom:      xrect.New(xrect.Pieces(c.frame.Geom())),
					headGeom:  xrect.New(xrect.Pieces(fakeWrk.HeadGeom())),
					frame:     c.frame,
					maximized: c.maximized,
				}
			}
		}
	}()

	// Any client that isn't normal doesn't get placed.
	// Let it do what it do, baby.
	if c.PrimaryType() != TypeNormal {
		return
	}

	// If it's sticky, let it do what it do.
	if _, ok := presumedWorkspace.(*workspace.Sticky); ok {
		return
	}

	// Transients never get placed.
	if c.transientFor != nil {
		return
	}

	// If a user/program position is specified, do not place.
	if c.nhints.Flags&icccm.SizeHintUSPosition > 0 ||
		c.nhints.Flags&icccm.SizeHintPPosition > 0 {

		return
	}

	// We're good, do a placement unless we're already mapped or on a
	// hidden workspace..
	if !presumedWorkspace.IsVisible() || !c.isAttrsUnmapped() {
		return
	}
	w := presumedWorkspace.(*workspace.Workspace)
	w.LayoutFloater().InitialPlacement(c)
}

func Maximize(f Frame) {
	hg := xrect.New(xrect.Pieces(f.Client().HeadGeom()))
	f.MoveResize(false, hg.X(), hg.Y(), hg.Width(), hg.Height())
}