/* 
 * tkFocus.c --
 *
 *	This file contains procedures that manage the input
 *	focus for Tk.
 *
 * Copyright (c) 1990-1994 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tkFocus.c,v 1.1.1.1 1999/06/25 17:35:57 damon Exp $
 */

#include "tkInt.h"
#include "tkPort.h"


/*
 * For each top-level window that has ever received the focus, there
 * is a record of the following type:
 */

typedef struct TkToplevelFocusInfo {
    TkWindow *topLevelPtr;	/* Information about top-level window. */
    TkWindow *focusWinPtr;	/* The next time the focus comes to this
				 * top-level, it will be given to this
				 * window. */
    struct TkToplevelFocusInfo *nextPtr;
				/* Next in list of all toplevel focus records
				 * for a given application. */
} ToplevelFocusInfo;

/*
 * One of the following structures exists for each display used by
 * each application.  These are linked together from the TkMainInfo
 * structure.  These structures are needed because it isn't
 * sufficient to store a single piece of focus information in each
 * display or in each application: we need the cross-product.
 * There needs to be separate information for each display, because
 * it's possible to have multiple focus windows active simultaneously
 * on different displays.  There also needs to be separate information
 * for each application, because of embedding: if an embedded
 * application has the focus, its container application also has
 * the focus.  Thus we keep a list of structures for each application:
 * the same display can appear in structures for several applications
 * at once.
 */

typedef struct TkDisplayFocusInfo {
    TkDisplay *dispPtr;		/* Display that this information pertains
				 * to. */
    struct TkWindow *focusWinPtr;
				/* Window that currently has the focus for
				 * this application on this display, or NULL
				 * if none. */
    struct TkWindow *focusOnMapPtr;
				/* This points to a toplevel window that is
				 * supposed to receive the X input focus as
				 * soon as it is mapped (needed to handle the
				 * fact that X won't allow the focus on an
				 * unmapped window).  NULL means no delayed
				 * focus op in progress for this display. */
    int forceFocus;		/* Associated with focusOnMapPtr:  non-zero
				 * means claim the focus even if some other
				 * application currently has it. */
    unsigned long focusSerial;	/* Serial number of last request this
				 * application made to change the focus on
				 * this display.  Used to identify stale
				 * focus notifications coming from the
				 * X server. */
    struct TkDisplayFocusInfo *nextPtr;
				/* Next in list of all display focus
				 * records for a given application. */
} DisplayFocusInfo;

/*
 * The following magic value is stored in the "send_event" field of
 * FocusIn and FocusOut events that are generated in this file.  This
 * allows us to separate "real" events coming from the server from
 * those that we generated.
 */

#define GENERATED_EVENT_MAGIC ((Bool) 0x547321ac)

/*
 * Forward declarations for procedures defined in this file:
 */


static DisplayFocusInfo *FindDisplayFocusInfo _ANSI_ARGS_((TkMainInfo *mainPtr,
			    TkDisplay *dispPtr));
static void		FocusMapProc _ANSI_ARGS_((ClientData clientData,
			    XEvent *eventPtr));
static void		GenerateFocusEvents _ANSI_ARGS_((TkWindow *sourcePtr,
			    TkWindow *destPtr));
static void		SetFocus _ANSI_ARGS_((TkWindow *winPtr, int force));

/*
 *--------------------------------------------------------------
 *
 * Tk_FocusObjCmd --
 *
 *	This procedure is invoked to process the "focus" Tcl command.
 *	See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *--------------------------------------------------------------
 */

int
Tk_FocusObjCmd(clientData, interp, objc, objv)
    ClientData clientData;	/* Main window associated with
				 * interpreter. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    static char *focusOptions[] = {"-displayof", "-force", "-lastfor",
				   (char *) NULL};
    Tk_Window tkwin = (Tk_Window) clientData;
    TkWindow *winPtr = (TkWindow *) clientData;
    TkWindow *newPtr, *focusWinPtr, *topLevelPtr;
    ToplevelFocusInfo *tlFocusPtr;
    char *windowName;
    int index;

    /*
     * If invoked with no arguments, just return the current focus window.
     */

    if (objc == 1) {
	focusWinPtr = TkGetFocusWin(winPtr);
	if (focusWinPtr != NULL) {
	    Tcl_SetResult(interp, focusWinPtr->pathName, TCL_STATIC);
	}
	return TCL_OK;
    }

    /*
     * If invoked with a single argument beginning with "." then focus
     * on that window.
     */

    if (objc == 2) {
	windowName = Tcl_GetStringFromObj(objv[1], (int *) NULL);

	/*
	 * The empty string case exists for backwards compatibility.
	 */
	
	if (windowName[0] == '\0') {
	    return TCL_OK;
	}
	if (windowName[0] == '.') {
	    newPtr = (TkWindow *) Tk_NameToWindow(interp, windowName, tkwin);
	    if (newPtr == NULL) {
		return TCL_ERROR;
	    }
	    if (!(newPtr->flags & TK_ALREADY_DEAD)) {
		SetFocus(newPtr, 0);
	    }
	    return TCL_OK;
	}
    }

    if (Tcl_GetIndexFromObj(interp, objv[1], focusOptions, "option", 0,
	    &index) != TCL_OK) {
    	return TCL_ERROR;
    }
    if (objc != 3) {
	Tcl_WrongNumArgs(interp, 2, objv, "window");
	return TCL_ERROR;
    }
    switch (index) {
        case 0: {        /* -displayof */
	    windowName = Tcl_GetStringFromObj(objv[2], (int *) NULL);
	    newPtr = (TkWindow *) Tk_NameToWindow(interp, windowName, tkwin);
	    if (newPtr == NULL) {
		return TCL_ERROR;
	    }
	    newPtr = TkGetFocusWin(newPtr);
	    if (newPtr != NULL) {
		Tcl_SetResult(interp, newPtr->pathName, TCL_STATIC);
	    }
	    break;
	}
        case 1: {        /* -force */
	    windowName = Tcl_GetStringFromObj(objv[2], (int *) NULL);

	    /*
	     * The empty string case exists for backwards compatibility.
	     */
	
	    if (windowName[0] == '\0') {
		return TCL_OK;
	    }
	    newPtr = (TkWindow *) Tk_NameToWindow(interp, windowName, tkwin);
	    if (newPtr == NULL) {
		return TCL_ERROR;
	    }
	    SetFocus(newPtr, 1);
	    break;
	}
        case 2: {        /* -lastfor */
	    windowName = Tcl_GetStringFromObj(objv[2], (int *) NULL);
	    newPtr = (TkWindow *) Tk_NameToWindow(interp, windowName, tkwin);
	    if (newPtr == NULL) {
		return TCL_ERROR;
	    }
	    for (topLevelPtr = newPtr; topLevelPtr != NULL;
		    topLevelPtr = topLevelPtr->parentPtr)  {
		if (topLevelPtr->flags & TK_TOP_LEVEL) {
		    for (tlFocusPtr = newPtr->mainPtr->tlFocusPtr;
			    tlFocusPtr != NULL;
			    tlFocusPtr = tlFocusPtr->nextPtr) {
		        if (tlFocusPtr->topLevelPtr == topLevelPtr) {
			    Tcl_SetResult(interp,
				    tlFocusPtr->focusWinPtr->pathName,
				    TCL_STATIC);
			    return TCL_OK;
			}
		    }
		    Tcl_SetResult(interp, topLevelPtr->pathName, TCL_STATIC);
		    return TCL_OK;
		}
	    }
	    break;
	}
	default: {
	    panic("bad const entries to focusOptions in focus command");
	}
    }
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * TkFocusFilterEvent --
 *
 *	This procedure is invoked by Tk_HandleEvent when it encounters
 *	a FocusIn, FocusOut, Enter, or Leave event.
 *
 * Results:
 *	A return value of 1 means that Tk_HandleEvent should process
 *	the event normally (i.e. event handlers should be invoked).
 *	A return value of 0 means that this event should be ignored.
 *
 * Side effects:
 *	Additional events may be generated, and the focus may switch.
 *
 *--------------------------------------------------------------
 */

int
TkFocusFilterEvent(winPtr, eventPtr)
    TkWindow *winPtr;		/* Window that focus event is directed to. */
    XEvent *eventPtr;		/* FocusIn, FocusOut, Enter, or Leave
				 * event. */
{
    /*
     * Design notes: the window manager and X server work together to
     * transfer the focus among top-level windows.  This procedure takes
     * care of transferring the focus from a top-level or wrapper window
     * to the actual window within that top-level that has the focus. 
     * We do this by synthesizing X events to move the focus around. 
     * None of the FocusIn and FocusOut events generated by X are ever
     * used outside of this procedure;  only the synthesized events get
     * through to the rest of the application.  At one point (e.g.
     * Tk4.0b1) Tk used to call X to move the focus from a top-level to
     * one of its descendants, then just pass through the events
     * generated by X. This approach didn't work very well, for a
     * variety of reasons. For example, if X generates the events they
     * go at the back of the event queue, which could cause problems if
     * other things have already happened, such as moving the focus to
     * yet another window.
     */

    ToplevelFocusInfo *tlFocusPtr;
    DisplayFocusInfo *displayFocusPtr;
    TkDisplay *dispPtr = winPtr->dispPtr;
    TkWindow *newFocusPtr;
    int retValue, delta;

    /*
     * If this was a generated event, just turn off the generated
     * flag and pass the event through to Tk bindings.
     */

    if (eventPtr->xfocus.send_event == GENERATED_EVENT_MAGIC) {
	eventPtr->xfocus.send_event = 0;
	return 1;
    }

    /*
     * Check for special events generated by embedded applications to
     * request the input focus.  If this is one of those events, make
     * the change in focus and return without any additional processing
     * of the event (note: the "detail" field of the event indicates
     * whether to claim the focus even if we don't already have it).
     */

    if ((eventPtr->xfocus.mode == EMBEDDED_APP_WANTS_FOCUS)
	    && (eventPtr->type == FocusIn)) {
	SetFocus(winPtr, eventPtr->xfocus.detail);
	return 0;
    }

    /*
     * This was not a generated event.  We'll return 1 (so that the
     * event will be processed) if it's an Enter or Leave event, and
     * 0 (so that the event won't be processed) if it's a FocusIn or
     * FocusOut event.
     */

    retValue = 0;
    displayFocusPtr = FindDisplayFocusInfo(winPtr->mainPtr, winPtr->dispPtr);
    if (eventPtr->type == FocusIn) {
	/*
	 * Skip FocusIn events that cause confusion
	 * NotifyVirtual and NotifyNonlinearVirtual - Virtual events occur
	 *	on windows in between the origin and destination of the
	 *	focus change.  For FocusIn we may see this when focus
	 *	goes into an embedded child.  We don't care about this,
	 *	although we may end up getting a NotifyPointer later.
	 * NotifyInferior - focus is coming to us from an embedded child.
	 *	When focus is on an embeded focus, we still think we have
	 *	the focus, too, so this message doesn't change our state.
	 * NotifyPointerRoot - should never happen because this is sent
	 *	to the root window.
	 *
	 * Interesting FocusIn events are
	 * NotifyAncestor - focus is coming from our parent, probably the root.
	 * NotifyNonlinear - focus is coming from a different branch, probably
	 *	another toplevel.
	 * NotifyPointer - implicit focus because of the mouse position.
	 *	This is	only interesting on toplevels, when it means that the
	 *	focus has been set to the root window but the mouse is over
	 *	this toplevel.  We take the focus implicitly (probably no
	 *	window manager)
	 */

	if ((eventPtr->xfocus.detail == NotifyVirtual)
		|| (eventPtr->xfocus.detail == NotifyNonlinearVirtual)
		|| (eventPtr->xfocus.detail == NotifyPointerRoot)
		|| (eventPtr->xfocus.detail == NotifyInferior)) {
	    return retValue;
	}
    } else if (eventPtr->type == FocusOut) {
	/*
	 * Skip FocusOut events that cause confusion.
	 * NotifyPointer - the pointer is in us or a child, and we are losing
	 *	focus because of an XSetInputFocus.  Other focus events
	 *	will set our state properly.
	 * NotifyPointerRoot - should never happen because this is sent
	 *	to the root window.
	 * NotifyInferior - focus leaving us for an embedded child.  We
	 *	retain a notion of focus when an embedded child has focus.
	 *
	 * Interesting events are:
	 * NotifyAncestor - focus is going to root.
	 * NotifyNonlinear - focus is going to another branch, probably
	 *	another toplevel.
	 * NotifyVirtual, NotifyNonlinearVirtual - focus is passing through,
	 *	and we need to make sure we track this.
	 */

	if ((eventPtr->xfocus.detail == NotifyPointer)
		|| (eventPtr->xfocus.detail == NotifyPointerRoot)
		|| (eventPtr->xfocus.detail == NotifyInferior)) {
	    return retValue;
	}
    } else {
	retValue = 1;
	if (eventPtr->xcrossing.detail == NotifyInferior) {
	    return retValue;
	}
    }

    /*
     * If winPtr isn't a top-level window than just ignore the event.
     */

    winPtr = TkWmFocusToplevel(winPtr);
    if (winPtr == NULL) {
	return retValue;
    }

    /*
     * If there is a grab in effect and this window is outside the
     * grabbed tree, then ignore the event.
     */

    if (TkGrabState(winPtr) == TK_GRAB_EXCLUDED)  {
	return retValue;
    }

    /*
     * It is possible that there were outstanding FocusIn and FocusOut
     * events on their way to us at the time the focus was changed
     * internally with the "focus" command.  If so, these events could
     * potentially cause us to lose the focus (switch it to the window
     * of the last FocusIn event) even though the focus change occurred
     * after those events.  The following code detects this and ignores
     * the stale events.
     *
     * Note: the focusSerial is only generated by TkpChangeFocus,
     * whereas in Tk 4.2 there was always a nop marker generated.
     */

    delta = eventPtr->xfocus.serial - displayFocusPtr->focusSerial;
    if (delta < 0) {
	return retValue;
    }

    /*
     * Find the ToplevelFocusInfo structure for the window, and make a new one
     * if there isn't one already.
     */

    for (tlFocusPtr = winPtr->mainPtr->tlFocusPtr; tlFocusPtr != NULL;
	    tlFocusPtr = tlFocusPtr->nextPtr) {
	if (tlFocusPtr->topLevelPtr == winPtr) {
	    break;
	}
    }
    if (tlFocusPtr == NULL) {
	tlFocusPtr = (ToplevelFocusInfo *) ckalloc(sizeof(ToplevelFocusInfo));
	tlFocusPtr->topLevelPtr = tlFocusPtr->focusWinPtr = winPtr;
	tlFocusPtr->nextPtr = winPtr->mainPtr->tlFocusPtr;
	winPtr->mainPtr->tlFocusPtr = tlFocusPtr;
    }
    newFocusPtr = tlFocusPtr->focusWinPtr;

    if (eventPtr->type == FocusIn) {
	GenerateFocusEvents(displayFocusPtr->focusWinPtr, newFocusPtr);
	displayFocusPtr->focusWinPtr = newFocusPtr;
	dispPtr->focusPtr = newFocusPtr;

	/*
	 * NotifyPointer gets set when the focus has been set to the root window
	 * but we have the pointer.  We'll treat this like an implicit
	 * focus in event so that upon Leave events we release focus.
	 */

	if (!(winPtr->flags & TK_EMBEDDED)) {
	    if (eventPtr->xfocus.detail == NotifyPointer) {
		dispPtr->implicitWinPtr = winPtr;
	    } else {
		dispPtr->implicitWinPtr = NULL;
	    }
	}
    } else if (eventPtr->type == FocusOut) {
	GenerateFocusEvents(displayFocusPtr->focusWinPtr, (TkWindow *) NULL);

	/*
	 * Reset dispPtr->focusPtr, but only if it currently is the same
	 * as this application's focusWinPtr: this check is needed to
	 * handle embedded applications in the same process.
	 */

	if (dispPtr->focusPtr == displayFocusPtr->focusWinPtr) {
	    dispPtr->focusPtr = NULL;
	}
	displayFocusPtr->focusWinPtr = NULL;
    } else if (eventPtr->type == EnterNotify) {
	/*
	 * If there is no window manager, or if the window manager isn't
	 * moving the focus around (e.g. the disgusting "NoTitleFocus"
	 * option has been selected in twm), then we won't get FocusIn
	 * or FocusOut events.  Instead, the "focus" field will be set
	 * in an Enter event to indicate that we've already got the focus
	 * when the mouse enters the window (even though we didn't get
	 * a FocusIn event).  Watch for this and grab the focus when it
	 * happens.  Note: if this is an embedded application then don't
	 * accept the focus implicitly like this;  the container
	 * application will give us the focus explicitly if it wants us
	 * to have it.
	 */

	if (eventPtr->xcrossing.focus &&
                (displayFocusPtr->focusWinPtr == NULL)
		&& !(winPtr->flags & TK_EMBEDDED)) {
	    if (dispPtr->focusDebug) {
		printf("Focussed implicitly on %s\n",
			newFocusPtr->pathName);
	    }

	    GenerateFocusEvents(displayFocusPtr->focusWinPtr, newFocusPtr);
	    displayFocusPtr->focusWinPtr = newFocusPtr;
	    dispPtr->implicitWinPtr = winPtr;
	    dispPtr->focusPtr = newFocusPtr;
	}
    } else if (eventPtr->type == LeaveNotify) {
	/*
	 * If the pointer just left a window for which we automatically
	 * claimed the focus on enter, move the focus back to the root
	 * window, where it was before we claimed it above.  Note:
	 * dispPtr->implicitWinPtr may not be the same as
	 * displayFocusPtr->focusWinPtr (e.g. because the "focus"
	 * command was used to redirect the focus after it arrived at
	 * dispPtr->implicitWinPtr)!!  In addition, we generate events
	 * because the window manager won't give us a FocusOut event when
	 * we focus on the root. 
	 */

	if ((dispPtr->implicitWinPtr != NULL)
		&& !(winPtr->flags & TK_EMBEDDED)) {
	    if (dispPtr->focusDebug) {
		printf("Defocussed implicit Async\n");
	    }
	    GenerateFocusEvents(displayFocusPtr->focusWinPtr,
		    (TkWindow *) NULL);
	    XSetInputFocus(dispPtr->display, PointerRoot, RevertToPointerRoot,
		    CurrentTime);
	    displayFocusPtr->focusWinPtr = NULL;
	    dispPtr->implicitWinPtr = NULL;
	}
    }
    return retValue;
}

/*
 *----------------------------------------------------------------------
 *
 * SetFocus --
 *
 *	This procedure is invoked to change the focus window for a
 *	given display in a given application.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Event handlers may be invoked to process the change of
 *	focus.
 *
 *----------------------------------------------------------------------
 */

static void
SetFocus(winPtr, force)
    TkWindow *winPtr;		/* Window that is to be the new focus for
				 * its display and application. */
    int force;			/* If non-zero, set the X focus to this
				 * window even if the application doesn't
				 * currently have the X focus. */
{
    ToplevelFocusInfo *tlFocusPtr;
    DisplayFocusInfo *displayFocusPtr;
    TkWindow *topLevelPtr;
    int allMapped, serial;

    displayFocusPtr = FindDisplayFocusInfo(winPtr->mainPtr, winPtr->dispPtr);

    /*
     * If force is set, we should make sure we grab the focus regardless
     * of the current focus window since under Windows, we may need to
     * take control away from another application.
     */

    if (winPtr == displayFocusPtr->focusWinPtr && !force) {
	return;
    }

    /*
     * Find the top-level window for winPtr, then find (or create)
     * a record for the top-level.  Also see whether winPtr and all its
     * ancestors are mapped.
     */

    allMapped = 1;
    for (topLevelPtr = winPtr; ; topLevelPtr = topLevelPtr->parentPtr)  {
	if (topLevelPtr == NULL) {
	    /*
	     * The window is being deleted.  No point in worrying about
	     * giving it the focus.
	     */
	    return;
	}
	if (!(topLevelPtr->flags & TK_MAPPED)) {
	    allMapped = 0;
	}
	if (topLevelPtr->flags & TK_TOP_LEVEL) {
	    break;
	}
    }

    /*
     * If the new focus window isn't mapped, then we can't focus on it
     * (X will generate an error, for example).  Instead, create an
     * event handler that will set the focus to this window once it gets
     * mapped.  At the same time, delete any old handler that might be
     * around;  it's no longer relevant.
     */

    if (displayFocusPtr->focusOnMapPtr != NULL) {
	Tk_DeleteEventHandler(
		(Tk_Window) displayFocusPtr->focusOnMapPtr,
		StructureNotifyMask, FocusMapProc,
		(ClientData) displayFocusPtr->focusOnMapPtr);
	displayFocusPtr->focusOnMapPtr = NULL;
    }
    if (!allMapped) {
	Tk_CreateEventHandler((Tk_Window) winPtr,
		VisibilityChangeMask, FocusMapProc,
		(ClientData) winPtr);
	displayFocusPtr->focusOnMapPtr = winPtr;
	displayFocusPtr->forceFocus = force;
	return;
    }

    for (tlFocusPtr = winPtr->mainPtr->tlFocusPtr; tlFocusPtr != NULL;
	    tlFocusPtr = tlFocusPtr->nextPtr) {
	if (tlFocusPtr->topLevelPtr == topLevelPtr) {
	    break;
	}
    }
    if (tlFocusPtr == NULL) {
	tlFocusPtr = (ToplevelFocusInfo *) ckalloc(sizeof(ToplevelFocusInfo));
	tlFocusPtr->topLevelPtr = topLevelPtr;
	tlFocusPtr->nextPtr = winPtr->mainPtr->tlFocusPtr;
	winPtr->mainPtr->tlFocusPtr = tlFocusPtr;
    }
    tlFocusPtr->focusWinPtr = winPtr;

    /*
     * Reset the window system's focus window and generate focus events,
     * with two special cases:
     *
     * 1. If the application is embedded and doesn't currently have the
     *    focus, don't set the focus directly.  Instead, see if the
     *    embedding code can claim the focus from the enclosing
     *    container.
     * 2. Otherwise, if the application doesn't currently have the
     *    focus, don't change the window system's focus unless it was
     *    already in this application or "force" was specified.
     */

    if ((topLevelPtr->flags & TK_EMBEDDED)
	    && (displayFocusPtr->focusWinPtr == NULL)) {
	TkpClaimFocus(topLevelPtr, force);
    } else if ((displayFocusPtr->focusWinPtr != NULL) || force) {
	/*
	 * Generate events to shift focus between Tk windows.
	 * We do this regardless of what TkpChangeFocus does with
	 * the real X focus so that Tk widgets track focus commands
	 * when there is no window manager.  GenerateFocusEvents will
	 * set up a serial number marker so we discard focus events
	 * that are triggered by the ChangeFocus.
	 */

	serial = TkpChangeFocus(TkpGetWrapperWindow(topLevelPtr), force);
	if (serial != 0) {
	    displayFocusPtr->focusSerial = serial;
	}
	GenerateFocusEvents(displayFocusPtr->focusWinPtr, winPtr);
	displayFocusPtr->focusWinPtr = winPtr;
	winPtr->dispPtr->focusPtr = winPtr;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TkGetFocusWin --
 *
 *	Given a window, this procedure returns the current focus
 *	window for its application and display.
 *
 * Results:
 *	The return value is a pointer to the window that currently
 *	has the input focus for the specified application and
 *	display, or NULL if none.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

TkWindow *
TkGetFocusWin(winPtr)
    TkWindow *winPtr;		/* Window that selects an application
				 * and a display. */
{
    DisplayFocusInfo *displayFocusPtr;

    if (winPtr == NULL) {
	return (TkWindow *) NULL;
    }

    displayFocusPtr = FindDisplayFocusInfo(winPtr->mainPtr, winPtr->dispPtr);
    return displayFocusPtr->focusWinPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * TkFocusKeyEvent --
 *
 *	Given a window and a key press or release event that arrived for
 *	the window, use information about the keyboard focus to compute
 *	which window should really get the event.  In addition, update
 *	the event to refer to its new window.
 *
 * Results:
 *	The return value is a pointer to the window that has the input
 *	focus in winPtr's application, or NULL if winPtr's application
 *	doesn't have the input focus.  If a non-NULL value is returned,
 *	eventPtr will be updated to refer properly to the focus window.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

TkWindow *
TkFocusKeyEvent(winPtr, eventPtr)
    TkWindow *winPtr;		/* Window that selects an application
				 * and a display. */
    XEvent *eventPtr;		/* X event to redirect (should be KeyPress
				 * or KeyRelease). */
{
    DisplayFocusInfo *displayFocusPtr;
    TkWindow *focusWinPtr;
    int focusX, focusY, vRootX, vRootY, vRootWidth, vRootHeight;

    displayFocusPtr = FindDisplayFocusInfo(winPtr->mainPtr, winPtr->dispPtr);
    focusWinPtr = displayFocusPtr->focusWinPtr;

    /*
     * The code below is a debugging aid to make sure that dispPtr->focusPtr
     * is kept properly in sync with the "truth", which is the value in
     * displayFocusPtr->focusWinPtr.
     */

#ifdef TCL_MEM_DEBUG
    if (focusWinPtr != winPtr->dispPtr->focusPtr) {
	printf("TkFocusKeyEvent found dispPtr->focusPtr out of sync:\n");
	printf("expected %s, got %s\n",
		(focusWinPtr != NULL) ? focusWinPtr->pathName : "??",
		(winPtr->dispPtr->focusPtr != NULL) ?
		winPtr->dispPtr->focusPtr->pathName : "??");
    }
#endif

    if ((focusWinPtr != NULL) && (focusWinPtr->mainPtr == winPtr->mainPtr)) {
	/*
	 * Map the x and y coordinates to make sense in the context of
	 * the focus window, if possible (make both -1 if the map-from
	 * and map-to windows don't share the same screen).
	 */

	if ((focusWinPtr->display != winPtr->display)
		|| (focusWinPtr->screenNum != winPtr->screenNum)) {
	    eventPtr->xkey.x = -1;
	    eventPtr->xkey.y = -1;
	} else {
	    Tk_GetVRootGeometry((Tk_Window) focusWinPtr, &vRootX, &vRootY,
		    &vRootWidth, &vRootHeight);
	    Tk_GetRootCoords((Tk_Window) focusWinPtr, &focusX, &focusY);
	    eventPtr->xkey.x = eventPtr->xkey.x_root - vRootX - focusX;
	    eventPtr->xkey.y = eventPtr->xkey.y_root - vRootY - focusY;
	}
	eventPtr->xkey.window = focusWinPtr->window;
	return focusWinPtr;
    }

    /*
     * The event doesn't belong to us.  Perhaps, due to embedding, it
     * really belongs to someone else.  Give the embedding code a chance
     * to redirect the event.
     */

    TkpRedirectKeyEvent(winPtr, eventPtr);
    return (TkWindow *) NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * TkFocusDeadWindow --
 *
 *	This procedure is invoked when it is determined that
 *	a window is dead.  It cleans up focus-related information
 *	about the window.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Various things get cleaned up and recycled.
 *
 *----------------------------------------------------------------------
 */

void
TkFocusDeadWindow(winPtr)
    register TkWindow *winPtr;		/* Information about the window
					 * that is being deleted. */
{
    ToplevelFocusInfo *tlFocusPtr, *prevPtr;
    DisplayFocusInfo *displayFocusPtr;
    TkDisplay *dispPtr = winPtr->dispPtr;

    /*
     * Search for focus records that refer to this window either as
     * the top-level window or the current focus window.
     */

    displayFocusPtr = FindDisplayFocusInfo(winPtr->mainPtr, winPtr->dispPtr);
    for (prevPtr = NULL, tlFocusPtr = winPtr->mainPtr->tlFocusPtr;
	    tlFocusPtr != NULL;
	    prevPtr = tlFocusPtr, tlFocusPtr = tlFocusPtr->nextPtr) {
	if (winPtr == tlFocusPtr->topLevelPtr) {
	    /*
	     * The top-level window is the one being deleted: free
	     * the focus record and release the focus back to PointerRoot
	     * if we acquired it implicitly.
	     */

	    if (dispPtr->implicitWinPtr == winPtr) {
		if (dispPtr->focusDebug) {
		    printf("releasing focus to root after %s died\n",
			    tlFocusPtr->topLevelPtr->pathName);
		}
		dispPtr->implicitWinPtr = NULL;
		displayFocusPtr->focusWinPtr = NULL;
		dispPtr->focusPtr = NULL;
	    }
	    if (displayFocusPtr->focusWinPtr == tlFocusPtr->focusWinPtr) {
		displayFocusPtr->focusWinPtr = NULL;
		dispPtr->focusPtr = NULL;
	    }
	    if (prevPtr == NULL) {
		winPtr->mainPtr->tlFocusPtr = tlFocusPtr->nextPtr;
	    } else {
		prevPtr->nextPtr = tlFocusPtr->nextPtr;
	    }
	    ckfree((char *) tlFocusPtr);
	    break;
	} else if (winPtr == tlFocusPtr->focusWinPtr) {
	    /*
	     * The deleted window had the focus for its top-level:
	     * move the focus to the top-level itself.
	     */

	    tlFocusPtr->focusWinPtr = tlFocusPtr->topLevelPtr;
	    if ((displayFocusPtr->focusWinPtr == winPtr)
		    && !(tlFocusPtr->topLevelPtr->flags & TK_ALREADY_DEAD)) {
		if (dispPtr->focusDebug) {
		    printf("forwarding focus to %s after %s died\n",
			    tlFocusPtr->topLevelPtr->pathName,
			    winPtr->pathName);
		}
		GenerateFocusEvents(displayFocusPtr->focusWinPtr,
			tlFocusPtr->topLevelPtr);
		displayFocusPtr->focusWinPtr = tlFocusPtr->topLevelPtr;
		dispPtr->focusPtr = tlFocusPtr->topLevelPtr;
	    }
	    break;
	}
    }

    if (displayFocusPtr->focusOnMapPtr == winPtr) {
	displayFocusPtr->focusOnMapPtr = NULL;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * GenerateFocusEvents --
 *
 *	This procedure is called to create FocusIn and FocusOut events to
 *	move the input focus from one window to another.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	FocusIn and FocusOut events are generated.
 *
 *----------------------------------------------------------------------
 */

static void
GenerateFocusEvents(sourcePtr, destPtr)
    TkWindow *sourcePtr;	/* Window that used to have the focus (may
				 * be NULL). */
    TkWindow *destPtr;		/* New window to have the focus (may be
				 * NULL). */

{
    XEvent event;
    TkWindow *winPtr;

    winPtr = sourcePtr;
    if (winPtr == NULL) {
	winPtr = destPtr;
	if (winPtr == NULL) {
	    return;
	}
    }

    event.xfocus.serial = LastKnownRequestProcessed(winPtr->display);
    event.xfocus.send_event = GENERATED_EVENT_MAGIC;
    event.xfocus.display = winPtr->display;
    event.xfocus.mode = NotifyNormal;
    TkInOutEvents(&event, sourcePtr, destPtr, FocusOut, FocusIn,
	    TCL_QUEUE_MARK);
}

/*
 *----------------------------------------------------------------------
 *
 * FocusMapProc --
 *
 *	This procedure is called as an event handler for VisibilityNotify
 *	events, if a window receives the focus at a time when its
 *	toplevel isn't mapped.  The procedure is needed because X
 *	won't allow the focus to be set to an unmapped window;  we
 *	detect when the toplevel is mapped and set the focus to it then.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	If this is a map event, the focus gets set to the toplevel
 *	given by clientData.
 *
 *----------------------------------------------------------------------
 */

static void
FocusMapProc(clientData, eventPtr)
    ClientData clientData;	/* Toplevel window. */
    XEvent *eventPtr;		/* Information about event. */
{
    TkWindow *winPtr = (TkWindow *) clientData;
    DisplayFocusInfo *displayFocusPtr;

    if (eventPtr->type == VisibilityNotify) {
	displayFocusPtr = FindDisplayFocusInfo(winPtr->mainPtr,
		winPtr->dispPtr);
	if (winPtr->dispPtr->focusDebug) {
	    printf("auto-focussing on %s, force %d\n", winPtr->pathName,
		    displayFocusPtr->forceFocus);
	}
	Tk_DeleteEventHandler((Tk_Window) winPtr, VisibilityChangeMask,
		FocusMapProc, clientData);
	displayFocusPtr->focusOnMapPtr = NULL;
	SetFocus(winPtr, displayFocusPtr->forceFocus);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * FindDisplayFocusInfo --
 *
 *	Given an application and a display, this procedure locate the
 *	focus record for that combination.  If no such record exists,
 *	it creates a new record and initializes it.
 *
 * Results:
 *	The return value is a pointer to the record.
 *
 * Side effects:
 *	A new record will be allocated if there wasn't one already.
 *
 *----------------------------------------------------------------------
 */

static DisplayFocusInfo *
FindDisplayFocusInfo(mainPtr, dispPtr)
    TkMainInfo *mainPtr;	/* Record that identifies a particular
				 * application. */
    TkDisplay *dispPtr;		/* Display whose focus information is
				 * needed. */
{
    DisplayFocusInfo *displayFocusPtr;

    for (displayFocusPtr = mainPtr->displayFocusPtr;
	    displayFocusPtr != NULL;
	    displayFocusPtr = displayFocusPtr->nextPtr) {
	if (displayFocusPtr->dispPtr == dispPtr) {
	    return displayFocusPtr;
	}
    }

    /*
     * The record doesn't exist yet.  Make a new one.
     */

    displayFocusPtr = (DisplayFocusInfo *) ckalloc(sizeof(DisplayFocusInfo));
    displayFocusPtr->dispPtr = dispPtr;
    displayFocusPtr->focusWinPtr = NULL;
    displayFocusPtr->focusOnMapPtr = NULL;
    displayFocusPtr->forceFocus = 0;
    displayFocusPtr->focusSerial = 0;
    displayFocusPtr->nextPtr = mainPtr->displayFocusPtr;
    mainPtr->displayFocusPtr = displayFocusPtr;
    return displayFocusPtr;
}
