enterleave.c   [plain text]

/*
 * Copyright © 2008 Red Hat, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Authors: Peter Hutterer
 *
 */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include <X11/X.h>
#include "windowstr.h"
#include "scrnintstr.h"
#include "exglobals.h"
#include "enterleave.h"

/* @file This file describes the model for sending core enter/leave events and
 * focus in/out in the case of multiple pointers/keyboard foci
 * Since we can't send more than one Enter or Leave/Focus in or out event per
 * window to a core client without confusing it, this is a rather complicated
 * approach.
 *
 * For a full description of the enter/leave model from a window's
 * perspective, see
 * http://lists.freedesktop.org/archives/xorg/2008-August/037606.html
 *
 * For a full description of the focus in/out model from a window's
 * perspective, see
 * http://lists.freedesktop.org/archives/xorg/2008-December/041740.html
 *
 * Additional notes:
 * -) The core protocol spec says that "In a LeaveNotify event, if a child of the
 * event window contains the initial position of the pointer, then the child
 * component is set to that child. Otherwise, it is None.  For an EnterNotify
 * event, if a child of the event window contains the final pointer position,
 * then the child component is set to that child. Otherwise, it is None."
 *
 * By inference, this means that only NotifyVirtual or NotifyNonlinearVirtual
 * events may have a subwindow set to other than None.
 *
 * -) NotifyPointer events may be sent if the focus changes from window A to
 * B. The assumption used in this model is that NotifyPointer events are only
 * sent for the pointer paired with the keyboard that is involved in the focus
 * events. For example, if F(W) changes because of keyboard 2, then
 * NotifyPointer events are only sent for pointer 2.
 */

static WindowPtr PointerWindows[MAXDEVICES];
static WindowPtr FocusWindows[MAXDEVICES];

/**
 * Return TRUE if @win has a pointer within its boundaries, excluding child
 * window.
 */
static BOOL
HasPointer(WindowPtr win)
{
    int i;

    for (i = 0; i < MAXDEVICES; i++)
        if (PointerWindows[i] == win)
            return TRUE;

    return FALSE;
}

/**
 * Return TRUE if at least one keyboard focus is set to @win (excluding
 * descendants of win).
 */
static BOOL
HasFocus(WindowPtr win)
{
    int i;
    for (i = 0; i < MAXDEVICES; i++)
        if (FocusWindows[i] == win)
            return TRUE;

    return FALSE;
}

/**
 * Return the window the device @dev is currently on.
 */
static WindowPtr
PointerWin(DeviceIntPtr dev)
{
    return PointerWindows[dev->id];
}

/**
 * Search for the first window below @win that has a pointer directly within
 * it's boundaries (excluding boundaries of its own descendants).
 *
 * @return The child window that has the pointer within its boundaries or
 *         NULL.
 */
static WindowPtr
FirstPointerChild(WindowPtr win)
{
    int i;
    for (i = 0; i < MAXDEVICES; i++)
    {
        if (PointerWindows[i] && IsParent(win, PointerWindows[i]))
            return PointerWindows[i];
    }

    return NULL;
}

/**
 * Search for the first window below @win that has a focus directly within
 * it's boundaries (excluding boundaries of its own descendants).
 *
 * @return The child window that has the pointer within its boundaries or
 *         NULL.
 */
static WindowPtr
FirstFocusChild(WindowPtr win)
{
    int i;
    for (i = 0; i < MAXDEVICES; i++)
    {
        if (FocusWindows[i] && FocusWindows[i] != PointerRootWin &&
            IsParent(win, FocusWindows[i]))
            return FocusWindows[i];
    }

    return NULL;
}

/**
 * Set the presence flag for @dev to mark that it is now in @win.
 */
void
EnterWindow(DeviceIntPtr dev, WindowPtr win, int mode)
{
    PointerWindows[dev->id] = win;
}

/**
 * Unset the presence flag for @dev to mark that it is not in @win anymore.
 */
static void
LeaveWindow(DeviceIntPtr dev, WindowPtr win, int mode)
{
    PointerWindows[dev->id] = NULL;
}

/**
 * Set the presence flag for @dev to mark that it is now in @win.
 */
void
SetFocusIn(DeviceIntPtr dev, WindowPtr win)
{
    FocusWindows[dev->id] = win;
}

/**
 * Unset the presence flag for @dev to mark that it is not in @win anymore.
 */
void
SetFocusOut(DeviceIntPtr dev, WindowPtr win)
{
    FocusWindows[dev->id] = NULL;
}




/**
 * @return The window that is the first ancestor of both a and b.
 */
WindowPtr
CommonAncestor(
    WindowPtr a,
    WindowPtr b)
{
    for (b = b->parent; b; b = b->parent)
	if (IsParent(b, a)) return b;
    return NullWindow;
}


#if 0
/**
 * Send enter notifies to all windows between @ancestor and @child (excluding
 * both). Events are sent running up the window hierarchy. This function
 * recurses.
 * If @core is TRUE, core events are sent, otherwise XI events will be sent.
 */
static void
DeviceEnterNotifies(DeviceIntPtr dev,
              WindowPtr ancestor,
              WindowPtr child,
              int mode,
              int detail)
{
    WindowPtr	parent = child->parent;

    if (ancestor == parent)
	return;
    DeviceEnterNotifies(dev, ancestor, parent, mode, detail);
    DeviceEnterLeaveEvent(dev, DeviceEnterNotify, mode, detail, parent,
                          child->drawable.id);
}
#endif

/**
 * Send enter notifies to all windows between @ancestor and @child (excluding
 * both). Events are sent running down the window hierarchy. This function
 * recurses.
 */
static void
CoreEnterNotifies(DeviceIntPtr dev,
                  WindowPtr ancestor,
                  WindowPtr child,
                  int mode,
                  int detail)
{
    WindowPtr	parent = child->parent;
    if (ancestor == parent)
	return;
    CoreEnterNotifies(dev, ancestor, parent, mode, detail);


    /* Case 3:
     A is above W, B is a descendant

      Classically: The move generates an EnterNotify on W with a detail of
        Virtual or NonlinearVirtual

     MPX:
        Case 3A: There is at least one other pointer on W itself
          P(W) doesn't change, so the event should be suppressed
        Case 3B: Otherwise, if there is at least one other pointer in a
          descendant
          P(W) stays on the same descendant, or changes to a different
          descendant. The event should be suppressed.
        Case 3C: Otherwise:
          P(W) moves from a window above W to a descendant. The subwindow
          field is set to the child containing the descendant. The detail
          may need to be changed from Virtual to NonlinearVirtual depending
          on the previous P(W). */

    if (!HasPointer(parent) && !FirstPointerChild(parent))
            CoreEnterLeaveEvent(dev, EnterNotify, mode, detail, parent,
                                child->drawable.id);
}

static void
CoreLeaveNotifies(DeviceIntPtr dev,
                  WindowPtr child,
                  WindowPtr ancestor,
                  int mode,
                  int detail)
{
    WindowPtr  win;

    if (ancestor == child)
        return;

    for (win = child->parent; win != ancestor; win = win->parent)
    {
        /*Case 7:
        A is a descendant of W, B is above W

        Classically: A LeaveNotify is generated on W with a detail of Virtual
          or NonlinearVirtual.

        MPX:
            Case 3A: There is at least one other pointer on W itself
              P(W) doesn't change, the event should be suppressed.
            Case 3B: Otherwise, if there is at least one other pointer in a
            descendant
             P(W) stays on the same descendant, or changes to a different
              descendant. The event should be suppressed.
            Case 3C: Otherwise:
              P(W) changes from the descendant of W to a window above W.
              The detail may need to be changed from Virtual to NonlinearVirtual
              or vice-versa depending on the new P(W).*/

        /* If one window has a pointer or a child with a pointer, skip some
         * work and exit. */
        if (HasPointer(win) || FirstPointerChild(win))
            return;

        CoreEnterLeaveEvent(dev, LeaveNotify, mode, detail, win, child->drawable.id);

        child = win;
    }
}

#if 0
/**
 * Send leave notifies to all windows between @child and @ancestor.
 * Events are sent running up the hierarchy.
 */
static void
DeviceLeaveNotifies(DeviceIntPtr dev,
              WindowPtr child,
              WindowPtr ancestor,
              int mode,
              int detail)
{
    WindowPtr  win;

    if (ancestor == child)
	return;
    for (win = child->parent; win != ancestor; win = win->parent)
    {
        DeviceEnterLeaveEvent(dev, DeviceLeaveNotify, mode, detail, win,
                                  child->drawable.id);
        child = win;
    }
}
#endif

/**
 * Pointer @dev moves from @A to @B and @A neither a descendant of @B nor is
 * @B a descendant of @A.
 */
static void
CoreEnterLeaveNonLinear(DeviceIntPtr dev,
                        WindowPtr A,
                        WindowPtr B,
                        int mode)
{
    WindowPtr X = CommonAncestor(A, B);
    /* Case 4:
     A is W, B is above W

    Classically: The move generates a LeaveNotify on W with a detail of
       Ancestor or Nonlinear

     MPX:
        Case 3A: There is at least one other pointer on W itself
          P(W) doesn't change, the event should be suppressed
        Case 3B: Otherwise, if there is at least one other pointer in a
        descendant of W
          P(W) changes from W to a descendant of W. The subwindow field
          is set to the child containing the new P(W), the detail field
          is set to Inferior
        Case 3C: Otherwise:
          The pointer window moves from W to a window above W.
          The detail may need to be changed from Ancestor to Nonlinear or
          vice versa depending on the the new P(W)
     */

    if (!HasPointer(A))
    {
        WindowPtr child = FirstPointerChild(A);
        if (child)
            CoreEnterLeaveEvent(dev, LeaveNotify, mode, NotifyInferior, A, None);
        else
            CoreEnterLeaveEvent(dev, LeaveNotify, mode, NotifyNonlinear, A, None);
    }


    CoreLeaveNotifies(dev, A, X, mode, NotifyNonlinearVirtual);

    /*
      Case 9:
        A is a descendant of W, B is a descendant of W

        Classically: No events are generated on W
        MPX: The pointer window stays the same or moves to a different
          descendant of W. No events should be generated on W.


       Therefore, no event to X.
    */

    CoreEnterNotifies(dev, X, B, mode, NotifyNonlinearVirtual);

    /* Case 2:
      A is above W, B=W

      Classically: The move generates an EnterNotify on W with a detail of
        Ancestor or Nonlinear

      MPX:
        Case 2A: There is at least one other pointer on W itself
          P(W) doesn't change, so the event should be suppressed
        Case 2B: Otherwise, if there is at least one other pointer in a
          descendant
          P(W) moves from a descendant to W. detail is changed to Inferior,
          subwindow is set to the child containing the previous P(W)
        Case 2C: Otherwise:
          P(W) changes from a window above W to W itself.
          The detail may need to be changed from Ancestor to Nonlinear
          or vice-versa depending on the previous P(W). */

     if (!HasPointer(B))
     {
         WindowPtr child = FirstPointerChild(B);
         if (child)
             CoreEnterLeaveEvent(dev, EnterNotify, mode, NotifyInferior, B, None);
         else
             CoreEnterLeaveEvent(dev, EnterNotify, mode, NotifyNonlinear, B, None);
     }
}

/**
 * Pointer @dev moves from @A to @B and @A is a descendant of @B.
 */
static void
CoreEnterLeaveToAncestor(DeviceIntPtr dev,
                         WindowPtr A,
                         WindowPtr B,
                         int mode)
{
    /* Case 4:
     A is W, B is above W

    Classically: The move generates a LeaveNotify on W with a detail of
       Ancestor or Nonlinear

     MPX:
        Case 3A: There is at least one other pointer on W itself
          P(W) doesn't change, the event should be suppressed
        Case 3B: Otherwise, if there is at least one other pointer in a
        descendant of W
          P(W) changes from W to a descendant of W. The subwindow field
          is set to the child containing the new P(W), the detail field
          is set to Inferior
        Case 3C: Otherwise:
          The pointer window moves from W to a window above W.
          The detail may need to be changed from Ancestor to Nonlinear or
          vice versa depending on the the new P(W)
     */
    if (!HasPointer(A))
    {
        WindowPtr child = FirstPointerChild(A);
        if (child)
            CoreEnterLeaveEvent(dev, LeaveNotify, mode, NotifyInferior, A, None);
        else
            CoreEnterLeaveEvent(dev, LeaveNotify, mode, NotifyAncestor, A, None);
    }

    CoreLeaveNotifies(dev, A, B, mode, NotifyVirtual);

    /* Case 8:
    A is a descendant of W, B is W

    Classically: A EnterNotify is generated on W with a detail of
        NotifyInferior

    MPX:
        Case 3A: There is at least one other pointer on W itself
          P(W) doesn't change, the event should be suppressed
        Case 3B: Otherwise:
          P(W) changes from a descendant to W itself. The subwindow
          field should be set to the child containing the old P(W) <<< WRONG */

    if (!HasPointer(B))
        CoreEnterLeaveEvent(dev, EnterNotify, mode, NotifyInferior, B, None);

}


/**
 * Pointer @dev moves from @A to @B and @B is a descendant of @A.
 */
static void
CoreEnterLeaveToDescendant(DeviceIntPtr dev,
                           WindowPtr A,
                           WindowPtr B,
                           int mode)
{
    /* Case 6:
    A is W, B is a descendant of W

    Classically: A LeaveNotify is generated on W with a detail of
       NotifyInferior

    MPX:
        Case 3A: There is at least one other pointer on W itself
          P(W) doesn't change, the event should be suppressed
        Case 3B: Otherwise:
          P(W) changes from W to a descendant of W. The subwindow field
          is set to the child containing the new P(W) <<< THIS IS WRONG */

    if (!HasPointer(A))
        CoreEnterLeaveEvent(dev, LeaveNotify, mode, NotifyInferior, A, None);


    CoreEnterNotifies(dev, A, B, mode, NotifyVirtual);

    /* Case 2:
      A is above W, B=W

      Classically: The move generates an EnterNotify on W with a detail of
        Ancestor or Nonlinear

      MPX:
        Case 2A: There is at least one other pointer on W itself
          P(W) doesn't change, so the event should be suppressed
        Case 2B: Otherwise, if there is at least one other pointer in a
          descendant
          P(W) moves from a descendant to W. detail is changed to Inferior,
          subwindow is set to the child containing the previous P(W)
        Case 2C: Otherwise:
          P(W) changes from a window above W to W itself.
          The detail may need to be changed from Ancestor to Nonlinear
          or vice-versa depending on the previous P(W). */

     if (!HasPointer(B))
     {
         WindowPtr child = FirstPointerChild(B);
         if (child)
             CoreEnterLeaveEvent(dev, EnterNotify, mode, NotifyInferior, B, None);
         else
             CoreEnterLeaveEvent(dev, EnterNotify, mode, NotifyAncestor, B, None);
     }
}

static void
CoreEnterLeaveEvents(DeviceIntPtr dev,
                     WindowPtr from,
                     WindowPtr to,
                     int mode)
{
    if (!dev->isMaster)
        return;

    LeaveWindow(dev, from, mode);

    if (IsParent(from, to))
        CoreEnterLeaveToDescendant(dev, from, to, mode);
    else if (IsParent(to, from))
        CoreEnterLeaveToAncestor(dev, from, to, mode);
    else
        CoreEnterLeaveNonLinear(dev, from, to, mode);

    EnterWindow(dev, to, mode);
}

#if 0
static void
DeviceEnterLeaveEvents(DeviceIntPtr dev,
                       WindowPtr    from,
                       WindowPtr    to,
                       int          mode)
{
    if (IsParent(from, to))
    {
        DeviceEnterLeaveEvent(dev, DeviceLeaveNotify, mode, NotifyInferior, from, None);
        DeviceEnterNotifies(dev, from, to, mode, NotifyVirtual);
        DeviceEnterLeaveEvent(dev, DeviceEnterNotify, mode, NotifyAncestor, to, None);
    }
    else if (IsParent(to, from))
    {
	DeviceEnterLeaveEvent(dev, DeviceLeaveNotify, mode, NotifyAncestor, from, None);
	DeviceLeaveNotifies(dev, from, to, mode, NotifyVirtual);
	DeviceEnterLeaveEvent(dev, DeviceEnterNotify, mode, NotifyInferior, to, None);
    }
    else
    { /* neither from nor to is descendent of the other */
	WindowPtr common = CommonAncestor(to, from);
	/* common == NullWindow ==> different screens */
        DeviceEnterLeaveEvent(dev, DeviceLeaveNotify, mode, NotifyNonlinear, from, None);
        DeviceLeaveNotifies(dev, from, common, mode, NotifyNonlinearVirtual);
        DeviceEnterNotifies(dev, common, to, mode, NotifyNonlinearVirtual);
        DeviceEnterLeaveEvent(dev, DeviceEnterNotify, mode, NotifyNonlinear, to, None);
    }
}
#endif

/**
 * Figure out if enter/leave events are necessary and send them to the
 * appropriate windows.
 *
 * @param fromWin Window the sprite moved out of.
 * @param toWin Window the sprite moved into.
 */
void
DoEnterLeaveEvents(DeviceIntPtr pDev,
        WindowPtr fromWin,
        WindowPtr toWin,
        int mode)
{
    if (!IsPointerDevice(pDev))
        return;

    if (fromWin == toWin)
	return;

    CoreEnterLeaveEvents(pDev, fromWin, toWin, mode);
#if 0
    DeviceEnterLeaveEvents(pDev, fromWin, toWin, mode);
#endif
}

/**
 * Send focus out events to all windows between @child and @ancestor.
 * Events are sent running up the hierarchy.
 */
static void
DeviceFocusOutEvents(DeviceIntPtr dev,
                     WindowPtr child,
                     WindowPtr ancestor,
                     int mode,
                     int detail)
{
    WindowPtr  win;

    if (ancestor == child)
	return;
    for (win = child->parent; win != ancestor; win = win->parent)
        DeviceFocusEvent(dev, DeviceFocusOut, mode, detail, win);
}


/**
 * Send enter notifies to all windows between @ancestor and @child (excluding
 * both). Events are sent running up the window hierarchy. This function
 * recurses.
 */
static void
DeviceFocusInEvents(DeviceIntPtr dev,
                    WindowPtr ancestor,
                    WindowPtr child,
                    int mode,
                    int detail)
{
    WindowPtr	parent = child->parent;

    if (ancestor == parent || !parent)
	return;
    DeviceFocusInEvents(dev, ancestor, parent, mode, detail);
    DeviceFocusEvent(dev, DeviceFocusIn, mode, detail, parent);
}

/**
 * Send FocusIn events to all windows between @ancestor and @child (excluding
 * both). Events are sent running down the window hierarchy. This function
 * recurses.
 */
static void
CoreFocusInEvents(DeviceIntPtr dev,
                  WindowPtr ancestor,
                  WindowPtr child,
                  int mode,
                  int detail)
{
    WindowPtr	parent = child->parent;
    if (ancestor == parent)
	return;
    CoreFocusInEvents(dev, ancestor, parent, mode, detail);


    /* Case 3:
     A is above W, B is a descendant

      Classically: The move generates an FocusIn on W with a detail of
        Virtual or NonlinearVirtual

     MPX:
        Case 3A: There is at least one other focus on W itself
          F(W) doesn't change, so the event should be suppressed
        Case 3B: Otherwise, if there is at least one other focus in a
          descendant
          F(W) stays on the same descendant, or changes to a different
          descendant. The event should be suppressed.
        Case 3C: Otherwise:
          F(W) moves from a window above W to a descendant. The detail may
          need to be changed from Virtual to NonlinearVirtual depending
          on the previous F(W). */

    if (!HasFocus(parent) && !FirstFocusChild(parent))
            CoreFocusEvent(dev, FocusIn, mode, detail, parent);
}

static void
CoreFocusOutEvents(DeviceIntPtr dev,
                   WindowPtr child,
                   WindowPtr ancestor,
                   int mode,
                   int detail)
{
    WindowPtr  win;

    if (ancestor == child)
        return;

    for (win = child->parent; win != ancestor; win = win->parent)
    {
        /*Case 7:
        A is a descendant of W, B is above W

        Classically: A FocusOut is generated on W with a detail of Virtual
          or NonlinearVirtual.

        MPX:
            Case 3A: There is at least one other focus on W itself
              F(W) doesn't change, the event should be suppressed.
            Case 3B: Otherwise, if there is at least one other focus in a
            descendant
             F(W) stays on the same descendant, or changes to a different
              descendant. The event should be suppressed.
            Case 3C: Otherwise:
              F(W) changes from the descendant of W to a window above W.
              The detail may need to be changed from Virtual to NonlinearVirtual
              or vice-versa depending on the new P(W).*/

        /* If one window has a focus or a child with a focuspointer, skip some
         * work and exit. */
        if (HasFocus(win) || FirstFocusChild(win))
            return;

        CoreFocusEvent(dev, FocusOut, mode, detail, win);
    }
}

/**
 * Send FocusOut(NotifyPointer) events from the current pointer window (which
 * is a descendant of @pwin_parent) up to (excluding) @pwin_parent.
 *
 * NotifyPointer events are only sent for the device paired with @dev.
 *
 * If the current pointer window is a descendat of @exclude or an ancestor of
 * @exclude, no events are sent. Note: If the current pointer IS @exclude,
 * events are sent!
 */
static void
CoreFocusOutNotifyPointerEvents(DeviceIntPtr dev,
                                WindowPtr pwin_parent,
                                WindowPtr exclude,
                                int mode,
                                int inclusive)
{
    WindowPtr P, stopAt;

    P = PointerWin(GetPairedDevice(dev));

    if (!P)
        return;
    if (!IsParent(pwin_parent, P))
        if (!(pwin_parent == P && inclusive))
            return;

    if (exclude != None && exclude != PointerRootWin &&
        (IsParent(exclude, P) || IsParent(P, exclude)))
        return;

    stopAt = (inclusive) ? pwin_parent->parent : pwin_parent;

    for (; P && P != stopAt; P = P->parent)
        CoreFocusEvent(dev, FocusOut, mode, NotifyPointer, P);
}

/**
 * DO NOT CALL DIRECTLY.
 * Recursion helper for CoreFocusInNotifyPointerEvents.
 */
static void
CoreFocusInRecurse(DeviceIntPtr dev,
                   WindowPtr win,
                   WindowPtr stopAt,
                   int mode,
                   int inclusive)
{
    if ((!inclusive && win == stopAt) || !win)
        return;

    CoreFocusInRecurse(dev, win->parent, stopAt, mode, inclusive);
    CoreFocusEvent(dev, FocusIn, mode, NotifyPointer, win);
}


/**
 * Send FocusIn(NotifyPointer) events from @pwin_parent down to
 * including the current pointer window (which is a descendant of @pwin_parent).
 * If @inclusive is TRUE, @pwin_parent will receive the event too.
 *
 * @pwin is the pointer window.
 *
 * If the current pointer window is a child of @exclude, no events are sent.
 */
static void
CoreFocusInNotifyPointerEvents(DeviceIntPtr dev,
                               WindowPtr pwin_parent,
                               WindowPtr exclude,
                               int mode,
                               int inclusive)
{
    WindowPtr P;

    P = PointerWin(GetPairedDevice(dev));

    if (!P || P == exclude || (pwin_parent != P && !IsParent(pwin_parent, P)))
        return;

    if (exclude != None && (IsParent(exclude, P) || IsParent(P, exclude)))
        return;

    CoreFocusInRecurse(dev, P, pwin_parent, mode, inclusive);
}


/**
 * Focus of @dev moves from @A to @B and @A neither a descendant of @B nor is
 * @B a descendant of @A.
 */
static void
CoreFocusNonLinear(DeviceIntPtr dev,
                   WindowPtr A,
                   WindowPtr B,
                   int mode)
{
    WindowPtr X = CommonAncestor(A, B);

    /* Case 4:
     A is W, B is above W

    Classically: The change generates a FocusOut on W with a detail of
       Ancestor or Nonlinear

     MPX:
        Case 3A: There is at least one other focus on W itself
          F(W) doesn't change, the event should be suppressed
        Case 3B: Otherwise, if there is at least one other focus in a
        descendant of W
          F(W) changes from W to a descendant of W. The detail field
          is set to Inferior
        Case 3C: Otherwise:
          The focus window moves from W to a window above W.
          The detail may need to be changed from Ancestor to Nonlinear or
          vice versa depending on the the new F(W)
     */

    if (!HasFocus(A))
    {
        WindowPtr child = FirstFocusChild(A);
        if (child)
        {
            /* NotifyPointer P-A unless P is child or below*/
            CoreFocusOutNotifyPointerEvents(dev, A, child, mode, FALSE);
            CoreFocusEvent(dev, FocusOut, mode, NotifyInferior, A);
        } else
        {
            /* NotifyPointer P-A */
            CoreFocusOutNotifyPointerEvents(dev, A, None, mode, FALSE);
            CoreFocusEvent(dev, FocusOut, mode, NotifyNonlinear, A);
        }
    }


    CoreFocusOutEvents(dev, A, X, mode, NotifyNonlinearVirtual);

    /*
      Case 9:
        A is a descendant of W, B is a descendant of W

        Classically: No events are generated on W
        MPX: The focus window stays the same or moves to a different
          descendant of W. No events should be generated on W.


       Therefore, no event to X.
    */

    CoreFocusInEvents(dev, X, B, mode, NotifyNonlinearVirtual);

    /* Case 2:
      A is above W, B=W

      Classically: The move generates an EnterNotify on W with a detail of
        Ancestor or Nonlinear

      MPX:
        Case 2A: There is at least one other focus on W itself
          F(W) doesn't change, so the event should be suppressed
        Case 2B: Otherwise, if there is at least one other focus in a
          descendant
          F(W) moves from a descendant to W. detail is changed to Inferior.
        Case 2C: Otherwise:
          F(W) changes from a window above W to W itself.
          The detail may need to be changed from Ancestor to Nonlinear
          or vice-versa depending on the previous F(W). */

     if (!HasFocus(B))
     {
         WindowPtr child = FirstFocusChild(B);
         if (child)
         {
             CoreFocusEvent(dev, FocusIn, mode, NotifyInferior, B);
             /* NotifyPointer B-P unless P is child or below. */
             CoreFocusInNotifyPointerEvents(dev, B, child, mode, FALSE);
         } else {
             CoreFocusEvent(dev, FocusIn, mode, NotifyNonlinear, B);
             /* NotifyPointer B-P unless P is child or below. */
             CoreFocusInNotifyPointerEvents(dev, B, None, mode, FALSE);
         }
     }
}


/**
 * Focus of @dev moves from @A to @B and @A is a descendant of @B.
 */
static void
CoreFocusToAncestor(DeviceIntPtr dev,
                    WindowPtr A,
                    WindowPtr B,
                    int mode)
{
    /* Case 4:
     A is W, B is above W

    Classically: The change generates a FocusOut on W with a detail of
       Ancestor or Nonlinear

     MPX:
        Case 3A: There is at least one other focus on W itself
          F(W) doesn't change, the event should be suppressed
        Case 3B: Otherwise, if there is at least one other focus in a
        descendant of W
          F(W) changes from W to a descendant of W. The detail field
          is set to Inferior
        Case 3C: Otherwise:
          The focus window moves from W to a window above W.
          The detail may need to be changed from Ancestor to Nonlinear or
          vice versa depending on the the new F(W)
     */
    if (!HasFocus(A))
    {
        WindowPtr child = FirstFocusChild(A);
        if (child)
        {
            /* NotifyPointer P-A unless P is child or below*/
            CoreFocusOutNotifyPointerEvents(dev, A, child, mode, FALSE);
            CoreFocusEvent(dev, FocusOut, mode, NotifyInferior, A);
        } else
            CoreFocusEvent(dev, FocusOut, mode, NotifyAncestor, A);
    }

    CoreFocusOutEvents(dev, A, B, mode, NotifyVirtual);

    /* Case 8:
    A is a descendant of W, B is W

    Classically: A FocusOut is generated on W with a detail of
        NotifyInferior

    MPX:
        Case 3A: There is at least one other focus on W itself
          F(W) doesn't change, the event should be suppressed
        Case 3B: Otherwise:
          F(W) changes from a descendant to W itself. */

    if (!HasFocus(B))
    {
        CoreFocusEvent(dev, FocusIn, mode, NotifyInferior, B);
        /* NotifyPointer B-P unless P is A or below. */
        CoreFocusInNotifyPointerEvents(dev, B, A, mode, FALSE);
    }
}

/**
 * Focus of @dev moves from @A to @B and @B is a descendant of @A.
 */
static void
CoreFocusToDescendant(DeviceIntPtr dev,
                      WindowPtr A,
                      WindowPtr B,
                      int mode)
{
    /* Case 6:
    A is W, B is a descendant of W

    Classically: A FocusOut is generated on W with a detail of
       NotifyInferior

    MPX:
        Case 3A: There is at least one other focus on W itself
          F(W) doesn't change, the event should be suppressed
        Case 3B: Otherwise:
          F(W) changes from W to a descendant of W. */

    if (!HasFocus(A))
    {
        /* NotifyPointer P-A unless P is B or below*/
        CoreFocusOutNotifyPointerEvents(dev, A, B, mode, FALSE);
        CoreFocusEvent(dev, FocusOut, mode, NotifyInferior, A);
    }


    CoreFocusInEvents(dev, A, B, mode, NotifyVirtual);

    /* Case 2:
      A is above W, B=W

      Classically: The move generates an FocusIn on W with a detail of
        Ancestor or Nonlinear

      MPX:
        Case 2A: There is at least one other focus on W itself
          F(W) doesn't change, so the event should be suppressed
        Case 2B: Otherwise, if there is at least one other focus in a
          descendant
          F(W) moves from a descendant to W. detail is changed to Inferior.
        Case 2C: Otherwise:
          F(W) changes from a window above W to W itself.
          The detail may need to be changed from Ancestor to Nonlinear
          or vice-versa depending on the previous F(W). */

     if (!HasFocus(B))
     {
         WindowPtr child = FirstFocusChild(B);
         if (child)
         {
             CoreFocusEvent(dev, FocusIn, mode, NotifyInferior, B);
             /* NotifyPointer B-P unless P is child or below. */
             CoreFocusInNotifyPointerEvents(dev, B, child, mode, FALSE);
         } else
             CoreFocusEvent(dev, FocusIn, mode, NotifyAncestor, B);
     }
}

static BOOL
HasOtherPointer(WindowPtr win, DeviceIntPtr exclude)
{
    int i;

    for (i = 0; i < MAXDEVICES; i++)
        if (i != exclude->id && PointerWindows[i] == win)
            return TRUE;

    return FALSE;
}

/**
 * Focus moves from PointerRoot to None or from None to PointerRoot.
 * Assumption: Neither A nor B are valid windows.
 */
static void
CoreFocusPointerRootNoneSwitch(DeviceIntPtr dev,
                               WindowPtr A, /* PointerRootWin or NoneWin */
                               WindowPtr B, /* NoneWin or PointerRootWin */
                               int mode)
{
    WindowPtr root;
    int i;
    int nscreens = screenInfo.numScreens;

#ifdef PANORAMIX
    if (!noPanoramiXExtension)
        nscreens = 1;
#endif

    for (i = 0; i < nscreens; i++)
    {
        root = WindowTable[i];
        if (!HasOtherPointer(root, GetPairedDevice(dev)) && !FirstFocusChild(root))
        {
            /* If pointer was on PointerRootWin and changes to NoneWin, and
             * the pointer paired with @dev is below the current root window,
             * do a NotifyPointer run. */
            if (dev->focus && dev->focus->win == PointerRootWin &&
                B != PointerRootWin)
            {
                WindowPtr ptrwin = PointerWin(GetPairedDevice(dev));
                if (ptrwin && IsParent(root, ptrwin))
                    CoreFocusOutNotifyPointerEvents(dev, root, None, mode, TRUE);
            }
            CoreFocusEvent(dev, FocusOut, mode, ((int)A) ? NotifyPointerRoot : NotifyDetailNone, root);
            CoreFocusEvent(dev, FocusIn, mode, ((int)B) ? NotifyPointerRoot : NotifyDetailNone, root);
            if (B == PointerRootWin)
                CoreFocusInNotifyPointerEvents(dev, root, None, mode, TRUE);
        }

    }
}

/**
 * Focus moves from window @A to PointerRoot or to None.
 * Assumption: @A is a valid window and not PointerRoot or None.
 */
static void
CoreFocusToPointerRootOrNone(DeviceIntPtr dev,
                       WindowPtr A,
                       WindowPtr B, /* PointerRootWin or NoneWin */
                       int mode)
{
    WindowPtr root;
    int i;
    int nscreens = screenInfo.numScreens;

#ifdef PANORAMIX
    if (!noPanoramiXExtension)
        nscreens = 1;
#endif

    if (!HasFocus(A))
    {
        WindowPtr child = FirstFocusChild(A);
        if (child)
        {
            /* NotifyPointer P-A unless P is B or below*/
            CoreFocusOutNotifyPointerEvents(dev, A, B, mode, FALSE);
            CoreFocusEvent(dev, FocusOut, mode, NotifyInferior, A);
        } else {
            /* NotifyPointer P-A */
            CoreFocusOutNotifyPointerEvents(dev, A, None, mode, FALSE);
            CoreFocusEvent(dev, FocusOut, mode, NotifyNonlinear, A);
        }
    }

    /* NullWindow means we include the root window */
    CoreFocusOutEvents(dev, A, NullWindow, mode, NotifyNonlinearVirtual);

    for (i = 0; i < nscreens; i++)
    {
        root = WindowTable[i];
        if (!HasFocus(root) && !FirstFocusChild(root))
        {
            CoreFocusEvent(dev, FocusIn, mode, ((int)B) ? NotifyPointerRoot : NotifyDetailNone, root);
            if (B == PointerRootWin)
                CoreFocusInNotifyPointerEvents(dev, root, None, mode, TRUE);
        }
    }
}

/**
 * Focus moves from PointerRoot or None to a window @to.
 * Assumption: @to is a valid window and not PointerRoot or None.
 */
static void
CoreFocusFromPointerRootOrNone(DeviceIntPtr dev,
                               WindowPtr A, /* PointerRootWin or NoneWin */
                               WindowPtr B,
                               int mode)
{
    WindowPtr root;
    int i;
    int nscreens = screenInfo.numScreens;

#ifdef PANORAMIX
    if (!noPanoramiXExtension)
        nscreens = 1;
#endif

    for (i = 0; i < nscreens; i++)
    {
        root = WindowTable[i];
        if (!HasFocus(root) && !FirstFocusChild(root))
        {
            /* If pointer was on PointerRootWin and changes to NoneWin, and
             * the pointer paired with @dev is below the current root window,
             * do a NotifyPointer run. */
            if (dev->focus && dev->focus->win == PointerRootWin &&
                B != PointerRootWin)
            {
                WindowPtr ptrwin = PointerWin(GetPairedDevice(dev));
                if (ptrwin)
                    CoreFocusOutNotifyPointerEvents(dev, root, None, mode, TRUE);
            }
            CoreFocusEvent(dev, FocusOut, mode, ((int)A) ? NotifyPointerRoot : NotifyDetailNone, root);
        }
    }

    root = B; /* get B's root window */
    while(root->parent)
        root = root->parent;

    if (B != root)
    {
        CoreFocusEvent(dev, FocusIn, mode, NotifyNonlinearVirtual, root);
        CoreFocusInEvents(dev, root, B, mode, NotifyNonlinearVirtual);
    }


    if (!HasFocus(B))
    {
        WindowPtr child = FirstFocusChild(B);
        if (child)
        {
             CoreFocusEvent(dev, FocusIn, mode, NotifyInferior, B);
             /* NotifyPointer B-P unless P is child or below. */
             CoreFocusInNotifyPointerEvents(dev, B, child, mode, FALSE);
        } else {
            CoreFocusEvent(dev, FocusIn, mode, NotifyNonlinear, B);
            /* NotifyPointer B-P unless P is child or below. */
            CoreFocusInNotifyPointerEvents(dev, B, None, mode, FALSE);
        }
    }

}

static void
CoreFocusEvents(DeviceIntPtr dev,
                WindowPtr from,
                WindowPtr to,
                int mode)
{
    if (!dev->isMaster)
        return;

    SetFocusOut(dev, from);

    if (((to == NullWindow) || (to == PointerRootWin)) &&
        ((from == NullWindow) || (from == PointerRootWin)))
        CoreFocusPointerRootNoneSwitch(dev, from, to, mode);
    else if ((to == NullWindow) || (to == PointerRootWin))
        CoreFocusToPointerRootOrNone(dev, from, to, mode);
    else if ((from == NullWindow) || (from == PointerRootWin))
        CoreFocusFromPointerRootOrNone(dev, from, to, mode);
    else if (IsParent(from, to))
        CoreFocusToDescendant(dev, from, to, mode);
    else if (IsParent(to, from))
        CoreFocusToAncestor(dev, from, to, mode);
    else
        CoreFocusNonLinear(dev, from, to, mode);

    SetFocusIn(dev, to);
}

#define RootWindow(dev) dev->spriteInfo->sprite->spriteTrace[0]

static void
DeviceFocusEvents(DeviceIntPtr dev,
                  WindowPtr from,
                  WindowPtr to,
                  int mode)
{
    int out, in;		       /* for holding details for to/from
                                          PointerRoot/None */
    int i;
    int nscreens = screenInfo.numScreens;
    SpritePtr sprite  = dev->spriteInfo->sprite;

    if (from == to)
        return;
    out = (from == NoneWin) ? NotifyDetailNone : NotifyPointerRoot;
    in = (to == NoneWin) ? NotifyDetailNone : NotifyPointerRoot;
    /* wrong values if neither, but then not referenced */

#ifdef PANORAMIX
    if (!noPanoramiXExtension)
        nscreens = 1;
#endif

    if ((to == NullWindow) || (to == PointerRootWin))
    {
        if ((from == NullWindow) || (from == PointerRootWin))
        {
            if (from == PointerRootWin)
                DeviceFocusOutEvents(dev, sprite->win, RootWindow(dev), mode,
                        NotifyPointer);
            /* Notify all the roots */
            for (i = 0; i < nscreens; i++)
                DeviceFocusEvent(dev, FocusOut, mode, out, WindowTable[i]);
        }
        else
        {
            if (IsParent(from, sprite->win))
                DeviceFocusOutEvents(dev, sprite->win, from, mode,
                        NotifyPointer);
            DeviceFocusEvent(dev, FocusOut, mode, NotifyNonlinear, from);
            /* next call catches the root too, if the screen changed */
            DeviceFocusOutEvents(dev, from->parent, NullWindow, mode,
                    NotifyNonlinearVirtual);
        }
        /* Notify all the roots */
        for (i = 0; i < nscreens; i++)
            DeviceFocusEvent(dev, FocusIn, mode, in, WindowTable[i]);
        if (to == PointerRootWin)
            DeviceFocusInEvents(dev, RootWindow(dev), sprite->win, mode, NotifyPointer);
    }
    else
    {
        if ((from == NullWindow) || (from == PointerRootWin))
        {
            if (from == PointerRootWin)
                DeviceFocusOutEvents(dev, sprite->win, RootWindow(dev), mode,
                        NotifyPointer);
            for (i = 0; i < nscreens; i++)
                DeviceFocusEvent(dev, FocusOut, mode, out, WindowTable[i]);
            if (to->parent != NullWindow)
                DeviceFocusInEvents(dev, RootWindow(dev), to, mode, NotifyNonlinearVirtual);
            DeviceFocusEvent(dev, FocusIn, mode, NotifyNonlinear, to);
            if (IsParent(to, sprite->win))
                DeviceFocusInEvents(dev, to, sprite->win, mode, NotifyPointer);
        }
        else
        {
            if (IsParent(to, from))
            {
                DeviceFocusEvent(dev, FocusOut, mode, NotifyAncestor, from);
                DeviceFocusOutEvents(dev, from->parent, to, mode,
                        NotifyVirtual);
                DeviceFocusEvent(dev, FocusIn, mode, NotifyInferior, to);
                if ((IsParent(to, sprite->win)) &&
                        (sprite->win != from) &&
                        (!IsParent(from, sprite->win)) &&
                        (!IsParent(sprite->win, from)))
                    DeviceFocusInEvents(dev, to, sprite->win, mode, NotifyPointer);
            }
            else
                if (IsParent(from, to))
                {
                    if ((IsParent(from, sprite->win)) &&
                            (sprite->win != from) &&
                            (!IsParent(to, sprite->win)) &&
                            (!IsParent(sprite->win, to)))
                        DeviceFocusOutEvents(dev, sprite->win, from, mode,
                                NotifyPointer);
                    DeviceFocusEvent(dev, FocusOut, mode, NotifyInferior, from);
                    DeviceFocusInEvents(dev, from, to, mode, NotifyVirtual);
                    DeviceFocusEvent(dev, FocusIn, mode, NotifyAncestor, to);
                }
                else
                {
                    /* neither from or to is child of other */
                    WindowPtr common = CommonAncestor(to, from);
                    /* common == NullWindow ==> different screens */
                    if (IsParent(from, sprite->win))
                        DeviceFocusOutEvents(dev, sprite->win, from, mode,
                                NotifyPointer);
                    DeviceFocusEvent(dev, FocusOut, mode, NotifyNonlinear, from);
                    if (from->parent != NullWindow)
                        DeviceFocusOutEvents(dev, from->parent, common, mode,
                                NotifyNonlinearVirtual);
                    if (to->parent != NullWindow)
                        DeviceFocusInEvents(dev, common, to, mode, NotifyNonlinearVirtual);
                    DeviceFocusEvent(dev, FocusIn, mode, NotifyNonlinear, to);
                    if (IsParent(to, sprite->win))
                        DeviceFocusInEvents(dev, to, sprite->win, mode, NotifyPointer);
                }
        }
    }
}

/**
 * Figure out if focus events are necessary and send them to the
 * appropriate windows.
 *
 * @param from Window the focus moved out of.
 * @param to Window the focus moved into.
 */
void
DoFocusEvents(DeviceIntPtr pDev,
              WindowPtr from,
              WindowPtr to,
              int mode)
{
    if (!IsKeyboardDevice(pDev))
        return;

    if (from == to)
	return;

    CoreFocusEvents(pDev, from, to, mode);
    DeviceFocusEvents(pDev, from, to, mode);
}