xref: /dports/x11-toolkits/xforms/xforms-1.2.4/lib/events.c

/*
 *  This file is part of the XForms library package.
 *
 *  XForms is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU Lesser General Public License as
 *  published by the Free Software Foundation; either version 2.1, or
 *  (at your option) any later version.
 *
 *  XForms is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with XForms.  If not, see <http://www.gnu.org/licenses/>.
 */


/**
 * \file events.c
 *
 *  This file is part of the XForms library package.
 *  Copyright (c) 1996-2002  T.C. Zhao and Mark Overmars
 *  All rights reserved.
 *
 *  Events handlers for the application window
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "include/forms.h"
#include "flinternal.h"
#include "private/flsnprintf.h"


static void handle_input_object( FL_OBJECT * obj,
                                 int         event );

/*** Global event handlers for all windows ******/

static FL_APPEVENT_CB fli_event_callback;
static void *fli_user_data;

FL_OBJECT *fli_handled_obj = NULL;
FL_OBJECT *fli_handled_parent = NULL;


/***************************************
 * Function returns 1 if the event is consumed so it will never
 * reach the application window event queue
 ***************************************/

int
fli_handle_event_callbacks( XEvent * xev )
{
    Window win = ( ( XAnyEvent * ) xev )->window;
    FLI_WIN *fwin = fli_app_win;

    while ( fwin && fwin->win != win )
        fwin = fwin->next;

    if ( ! fwin )
    {
        /* If there's a callback for events for independendly created user
           windows that returns 0 the event has been handled, otherwise
           ignore it */

        if ( fli_event_callback && ! fli_event_callback( xev, fli_user_data ) )
            return 1;

        M_warn( "fli_handle_event_callbacks", "Unknown window = %ld",
                xev->xany.window );
        fli_xevent_name( "Ignored", xev );
        return 1;
    }

    if (    fwin->pre_emptive
         && fwin->pre_emptive( xev, fwin->pre_emptive_data ) == FL_PREEMPT )
        return 1;

    if ( fwin->callback[ xev->type ] )
    {
        fwin->callback[ xev->type ]( xev, fwin->user_data[ xev->type ] );
        return 1;
    }

    return 0;
}


/***************************************
 * Sets the callback routine for the events
 ***************************************/

FL_APPEVENT_CB
fl_set_event_callback( FL_APPEVENT_CB callback,
                       void *         user_data )
{
    FL_APPEVENT_CB old = fli_event_callback;

    fli_event_callback = callback;
    fli_user_data = user_data;
    return old;
}


/********* End of Application Window management ***********}*****/


/*************** THE OBJECT EVENTS *************{******/
/*************** CALL-BACK ROUTINE HANDLING ***********/

/* Normally, the object queue doesn't have to be large and a default
   size is sufficient. In the case that more objects need to be
   stored the queue isn't increased by just another element but
   instead by the same number of objects we started with, reducing
   the number of calls of malloc() a bit */

#define FLI_QSIZE         64            /* chunk size of object queue */

typedef struct FLI_OBJECT_QUEUE_ENTRY_ {
    FL_OBJECT *                      obj;
    int                              ret;
    int                              event;
    struct FLI_OBJECT_QUEUE_ENTRY_ * next;
} FLI_OBJECT_QUEUE_ENTRY;

typedef struct FLI_OBJECT_QUEUE_ {
    FLI_OBJECT_QUEUE_ENTRY * head;       /* here objects get added to */
    FLI_OBJECT_QUEUE_ENTRY * tail;       /* and here they get removed from */
    FLI_OBJECT_QUEUE_ENTRY * empty;      /* linked list of empty entries */
    FLI_OBJECT_QUEUE_ENTRY * blocks;     /* pointer to linked list of blocks */
} FLI_OBJECT_QUEUE;

static FLI_OBJECT_QUEUE obj_queue = { NULL, NULL, NULL, NULL };


/***************************************************
 * Function for creating/extending the object queue
 * (gets called automatically the first time an
 * object gets pushed on the queue, so no previous
 * call, e.g. from fl_initialize(), is necessary)
 ***************************************************/

static void
extend_obj_queue( void )
{
    FLI_OBJECT_QUEUE_ENTRY *p = fl_malloc( ( FLI_QSIZE + 1 ) * sizeof *p );
    size_t i;

    /* The first element of the (new) area is used for book-keeping purposes */

    p->next = obj_queue.blocks;
    obj_queue.blocks = p++;

    /* The rest gets added to (or makes up) the empty list */

    obj_queue.empty = p;

    for ( i = 0; i < FLI_QSIZE - 1; p++, i++ )
        p->next = p + 1;

    p->next = NULL;
}


/******************************************************
 * Fuction for removing the object queue, should be
 * called when all forms and application windows have
 * been closed to get rid of allocated memory.
 ******************************************************/

void
fli_obj_queue_delete( void )
{
    FLI_OBJECT_QUEUE_ENTRY *b;

    while ( ( b = obj_queue.blocks ) != NULL )
    {
        obj_queue.blocks = b->next;
        fl_free( b );
    }

    obj_queue.tail = obj_queue.head = obj_queue.empty = NULL;
}


/***********************************************************
 * Function for appending a new element to the object queue
 ***********************************************************/

static void
add_to_obj_queue( FL_OBJECT * obj,
                  int         event )
{
    if ( obj == NULL )
        return;

    if ( obj_queue.empty == NULL )
        extend_obj_queue( );

    if ( obj_queue.head )
        obj_queue.head = obj_queue.head->next = obj_queue.empty;
    else
        obj_queue.tail = obj_queue.head = obj_queue.empty;

    obj_queue.empty = obj_queue.empty->next;

    obj_queue.head->next = NULL;
    obj_queue.head->obj = obj;
    obj_queue.head->event = event;
    if ( obj != FL_EVENT )
        obj_queue.head->ret = obj->returned;
}


/*****************************************************************
 * Function for fetching the oldest element from the object queue
 *****************************************************************/

static FL_OBJECT *
get_from_obj_queue( int * event )
{
    FLI_OBJECT_QUEUE_ENTRY *t = obj_queue.tail;

    if ( t == NULL )
        return NULL;

    if ( t->next == NULL )
        obj_queue.tail = obj_queue.head = NULL;
    else
        obj_queue.tail = t->next;

    t->next = obj_queue.empty;
    obj_queue.empty = t;

    if ( t->obj != FL_EVENT )
        t->obj->returned = t->ret;

    if ( event )
        *event = t->event;

    return t->obj;
}


/*************************************************************************
 * Function for removing all entries for a certain object from the queue.
 * This routine is called as part of hiding and deletion of an object.
 *************************************************************************/

void
fli_object_qflush_object( FL_OBJECT * obj )
{
    FLI_OBJECT_QUEUE_ENTRY *c,
                           *p;

    while ( obj_queue.tail && obj_queue.tail->obj == obj )
        get_from_obj_queue( NULL );

    if ( ! obj_queue.tail )
        return;

    p = obj_queue.tail;
    c = p->next;

    while ( c )
    {
        if ( c->obj == obj )
        {
            p->next = c->next;
            c->next = obj_queue.empty;
            obj_queue.empty = c;
        }
        else
            p = c;

        c = p->next;
    }
}


/**********************************************************************
 * Function for removing all entries for a certain form from the queue
 * - here the object handler must be executed for FL_INPUT objects.
 * This should be called as part of free_form process.
 **********************************************************************/

void
fli_object_qflush( FL_FORM * form )
{
    FLI_OBJECT_QUEUE_ENTRY *c,
                           *p;

    while (    obj_queue.tail
            && obj_queue.tail->obj != FL_EVENT
            && obj_queue.tail->obj->form == form )
    {
        if ( obj_queue.tail->obj->objclass == FL_INPUT )
            handle_input_object( obj_queue.tail->obj,
                                 obj_queue.tail->event );
        get_from_obj_queue( NULL );
    }

    if ( ! obj_queue.tail )
        return;

    for ( p = obj_queue.tail, c = p->next; c != NULL; c = p->next )
        if ( c->obj != FL_EVENT && c->obj->form == form )
        {
            if ( c->obj->objclass == FL_INPUT )
                handle_input_object( c->obj, c->event );

            p->next = c->next;
            c->next = obj_queue.empty;
            obj_queue.empty = c;
        }
        else
            p = c;
}


/***************************************
 * Adds an object to the queue
 ***************************************/

void
fli_object_qenter( FL_OBJECT * obj,
                   int         event )
{
    if ( ! obj )
    {
        M_err( "fli_object_qenter", "NULL object" );
        return;
    }

#ifndef DELAYED_ACTION
    if (    obj != FL_EVENT
         && ( ! obj->form || ! obj->visible || obj->active <= 0 ) )
    {
#if FL_DEBUG >= ML_DEBUG
        M_err( "fli_object_qenter", "Bad object" );
#endif
        return;
    }

    /* Please note: if 'DELAYED_ACTION' should ever be switched on don't
       forget to deal correctly with also handling callbacks of parent
       objects (if the object entered is a child object) */

    if ( obj != FL_EVENT )
    {
        if ( obj->object_callback )
        {
            XFlush( flx->display );
            fli_context->last_event = event;
            obj->object_callback( obj, obj->argument );
            fli_context->last_event = FL_NOEVENT;
            return;
        }
        else if ( obj->form->form_callback )
        {
            XFlush( flx->display );
            fli_context->last_event = event;
            obj->form->form_callback( obj, obj->form->form_cb_data );
            fli_context->last_event = FL_NOEVENT;
            return;
        }
    }
#endif /* ! DELAYED_ACTION */

    add_to_obj_queue( obj, event );
}


/***************************************
 * Returns a pointer to the oldest element in the object queue
 ***************************************/

FL_OBJECT *
fli_object_qtest( void )
{
    return obj_queue.tail ? obj_queue.tail->obj : NULL;
}


/***************************************
 * Filter out result bits that don't fit what the object is set up to
 * return, and make sure the FL_RETURN_END_CHANGED bit is set correctly,
 * which requires that both FL_RETURN_CHANGED and FL_RETURN_END are set
 ***************************************/

void
fli_filter_returns( FL_OBJECT * obj )
{
    if (    obj->how_return & FL_RETURN_END_CHANGED
         && obj->returned & FL_RETURN_CHANGED
         && obj->returned & FL_RETURN_END )
    {
        obj->returned |= FL_RETURN_END_CHANGED;
        obj->returned &= ~ ( FL_RETURN_CHANGED | FL_RETURN_END );
    }

    if ( obj->how_return != FL_RETURN_NONE )
        obj->returned &= obj->how_return | FL_RETURN_TRIGGERED;
    else
        obj->returned = FL_RETURN_NONE;
}


/***************************************
 * Reads an object from the queue, calls callbacks for the object (if
 * they exist) or passes it on to the user via fl_do_forms() etc.
 ***************************************/

FL_OBJECT *
fli_object_qread( void )
{
    int event = -1;
    FL_OBJECT *obj = get_from_obj_queue( &event );

    if ( obj == FL_EVENT )
        return obj;

    if ( ! obj || ! obj->form )
        return NULL;

    /* If the object has a callback execute it and return NULL unless the
       object is a child object (in that case we're supposed to also check
       for callbacks for the parent etc.). It's also important to make
       sure the object didn't get deleted within its callback - if that's
       the case it would be catastrophic to check for the parent... */

    if ( obj->object_callback )
    {
        fli_handled_obj = obj;

        fli_context->last_event = event;
        obj->object_callback( obj, obj->argument );
        fli_context->last_event = FL_NOEVENT;

        if ( fli_handled_obj )
            obj->returned = FL_RETURN_NONE;

        if ( ! fli_handled_obj || ! obj->parent )
            return NULL;
    }

    /* If the object is a child object check if there is a callback for
       the parent and execute that (and return NULL in that case). In
       between also check if there are further events for other childs
       of the same parent in the queue and also execute their callbacks.
       And keep in mind that execution of one of these callbacks may
       delete the object (and even its parent...) */

    if ( obj->parent )
    {
        obj = obj->parent;
        fli_filter_returns( obj );

        while ( obj->parent )
        {
            if ( ! obj->returned )
                return NULL;

            if ( obj->object_callback )
            {
                fli_handled_obj = obj;
                fli_context->last_event = event;
                obj->object_callback( obj, obj->argument );
                fli_context->last_event = FL_NOEVENT;
                if ( fli_handled_obj )
                    obj->returned = FL_RETURN_NONE;
                else
                    return NULL;
            }

            obj = obj->parent;
            fli_filter_returns( obj );
        }

        fli_handled_parent = obj;

        while ( fli_handled_parent )
        {
            FL_OBJECT *n,
                      *p;

            if (    ! ( n = fli_object_qtest( ) )
                 || n == FL_EVENT
                 || ! n->parent )
                break;

            p = n->parent;
            while ( p->parent )
                p = p->parent;

            if ( p != obj )
                break;

            n = get_from_obj_queue( &event );
            do
            {
                fli_filter_returns( n );
                if ( ! n->returned )
                    break;

                if ( n->object_callback )
                {
                    fli_handled_obj = n;
                    fli_context->last_event = event;
                    n->object_callback( n, n->argument );
                    fli_context->last_event = FL_NOEVENT;
                    if ( fli_handled_obj )
                        n->returned = FL_RETURN_NONE;
                    else
                        break;
                }
            } while ( fli_handled_parent && ( n = n->parent ) != obj );

            fli_filter_returns( obj );
        }

        if ( ! fli_handled_parent )
            return NULL;
    }

    /* If we arrive here the original object either was a child object
       or it had no callback. Run either the parents callback or the forms
       callback (if there's one). */

    if ( ! obj->returned )
        return NULL;
    else if ( obj->object_callback  )
    {
        fli_handled_obj = obj;
        fli_context->last_event = event;
        obj->object_callback( obj, obj->argument );
        fli_context->last_event = FL_NOEVENT;
        if ( fli_handled_obj )
            obj->returned = FL_RETURN_NONE;
        return NULL;
    }
    else if ( obj->form->form_callback )
    {
        fli_handled_obj = obj;
        fli_context->last_event = event;
        obj->form->form_callback( obj, obj->form->form_cb_data );
        fli_context->last_event = FL_NOEVENT;
        if ( fli_handled_obj )
            obj->returned = FL_RETURN_NONE;
        return NULL;
    }

    if ( obj->child && obj->returned == FL_RETURN_NONE)
        return NULL;

    return obj;
}


/***************************************
 * This is mainly used to handle the input correctly when a form
 * is being hidden
 ***************************************/

static void
handle_input_object( FL_OBJECT * obj,
                     int         event )
{
    if ( obj != FL_EVENT || ! obj->form )
        return;

    fli_context->last_event = event;
    if ( obj->object_callback )
        obj->object_callback( obj, obj->argument );
    else if ( obj->form->form_callback )
        obj->form->form_callback( obj, obj->form->form_cb_data );
    fli_context->last_event = FL_NOEVENT;
}


/***************** End of object queue handling *****************/



/**************** Normal Events ********************/


typedef struct FL_EVENT_QUEUE_ENTRY_ {
    XEvent                         xev;
    struct FL_EVENT_QUEUE_ENTRY_ * next;
} FL_EVENT_QUEUE_ENTRY;


typedef struct FL_EVENT_QUEUE_ {
    FL_EVENT_QUEUE_ENTRY * head;       /* here events get added to */
    FL_EVENT_QUEUE_ENTRY * tail;       /* and here they get removed from */
    FL_EVENT_QUEUE_ENTRY * empty;      /* linked list of empty entries */
    FL_EVENT_QUEUE_ENTRY * blocks;     /* pointer to linked list of blocks */
    unsigned long          count;
} FL_EVENT_QUEUE;

static FL_EVENT_QUEUE event_queue = { NULL, NULL, NULL, NULL, 0 };


/***************************************************
 * Function for creating/extending the event queue
 * (gets called automatically the first time an
 * event gets pushed onto the queue, so no initia-
 * lization, e.g. from fl_initialize(), is needed)
 ***************************************************/

static void
extend_event_queue( void )
{
    FL_EVENT_QUEUE_ENTRY *p = fl_malloc( ( FLI_QSIZE + 1 ) * sizeof *p );
    size_t i;

    /* The first element of the area gets used for book-keeping purposes */

    p->next = event_queue.blocks;
    event_queue.blocks = p++;

    /* The rest gets added to (or makes up) the empty list */

    event_queue.empty = p;

    for ( i = 0; i < FLI_QSIZE - 1; p++, i++ )
        p->next = p + 1;

    p->next = NULL;
}


/******************************************************
 * Fuction for removing the event queue, should be
 * called when all forms and application windows have
 * been closed to get rid of allocated memory.
 ******************************************************/

void
fli_event_queue_delete( void )
{
    FL_EVENT_QUEUE_ENTRY *b;

    while ( ( b = event_queue.blocks ) != NULL )
    {
        event_queue.blocks = b->next;
        fl_free( b );
    }

    event_queue.tail = event_queue.head = event_queue.empty = NULL;
}


/***********************************************************
 * Function for appending a new element to the event queue
 ***********************************************************/

static void
add_to_event_queue( XEvent * xev )
{
    if ( event_queue.empty == NULL )
        extend_event_queue( );

    if ( event_queue.head )
        event_queue.head = event_queue.head->next = event_queue.empty;
    else
        event_queue.tail = event_queue.head = event_queue.empty;

    event_queue.empty = event_queue.empty->next;

    event_queue.head->next = NULL;
    event_queue.head->xev = *xev;
    event_queue.count++;
}


/****************************************************************
 * Function for removing the oldest element form the event queue
 ****************************************************************/

static XEvent
get_from_event_queue( void )
{
    FL_EVENT_QUEUE_ENTRY *t = event_queue.tail;

    if ( t->next == NULL )
        event_queue.tail = event_queue.head = NULL;
    else
        event_queue.tail = t->next;

    t->next = event_queue.empty;
    event_queue.empty = t;

    return t->xev;
}


/***************************************
 * Replacement for the Xlib XPutBackEvent() function:
 * allows to push back an event onto the queue
 ***************************************/

void
fl_XPutBackEvent( XEvent * xev )
{
    static int mm;

    if ( xev->type != ClientMessage && fli_handle_event_callbacks( xev ) )
        return;

    /* These must have come from simulating double buffering, throw them away */

    if ( xev->type == NoExpose )
    {
        if ( ++mm % 20 == 0 )
        {
            M_warn( "fl_XPutbackEvent", "20 NoExpose discarded" );
            mm = 0;
        }

        return;
    }

    fli_xevent_name( "fl_XPutBackEvent", xev );
    add_to_event_queue( xev );
}


/***************************************
 * Replacement for the Xlib XEventsQueued() function: returns
 * if there are any events in the event queue.
 ***************************************/

int
fl_XEventsQueued( int mode  FL_UNUSED_ARG )
{
    if ( event_queue.tail == NULL )
    {
        if ( fl_display == None )
            return 0;

        fli_treat_interaction_events( 0 );
        fli_treat_user_events( );
    }

    return event_queue.tail != NULL;
}


/***************************************
 * Replacement for the Xlib XNextEvent() function: copies the oldest
 * event into the XEvent structure and removes it from the queue. If
 * the queue is empty it blocks until an event has been received.
 ***************************************/

int
fl_XNextEvent( XEvent * xev )
{
    if ( fl_display == None )
        return 0;

    while ( event_queue.tail == NULL )
    {
        if ( fl_display == None )
            return 0;

        fli_treat_interaction_events( 1 );
        fli_treat_user_events( );
    }

    *xev = get_from_event_queue( );
    return 1;
}


/***************************************
 * Replacement for the Xlib XPeekEvent() function: returns a copy
 * of the first event avaialable but does not remove it. Blocks
 * if there is no event until a new one has arrived.
 ***************************************/

int
fl_XPeekEvent( XEvent * xev )
{
    if ( fl_display == None )
        return 0;

    while ( event_queue.tail == NULL )
    {
        if ( fl_display == None )
            return 0;

        fli_treat_interaction_events( 1 );
        fli_treat_user_events( );
    }

    *xev = event_queue.tail->xev;
    return 1;
}


/***************************************
 * Get all user events and treat them: either "consume" them by
 * calling the callback routine or put them onto the internal
 * object queue for later retrival
 ***************************************/

void
fli_treat_user_events( void )
{
    XEvent xev;

    while ( fl_display != None && event_queue.count )
    {
        if ( fli_event_callback )
        {
            fl_XNextEvent( &xev );
            fli_event_callback( &xev, fli_user_data );
        }
        else
            fli_object_qenter( FL_EVENT, FL_NOEVENT );

        event_queue.count--;
    }
}


/******************** DEBUG use only *****************/


#define NV( a ) { #a, a }

typedef struct
{
    const char * name;
    int          type;
} ev_name;


static ev_name evname[ ] =
{
    NV( 0 ),
    NV( 1 ),
    NV( KeyPress ),
    NV( KeyRelease ),
    NV( ButtonPress ),
    NV( ButtonRelease ),
    NV( MotionNotify ),
    NV( EnterNotify ),
    NV( LeaveNotify ),
    NV( FocusIn ),
    NV( FocusOut ),
    NV( KeymapNotify ),
    NV( Expose ),
    NV( GraphicsExpose ),
    NV( NoExpose ),
    NV( VisibilityNotify ),
    NV( CreateNotify ),
    NV( DestroyNotify ),
    NV( UnmapNotify ),
    NV( MapNotify ),
    NV( MapRequest ),
    NV( ReparentNotify ),
    NV( ConfigureNotify ),
    NV( ConfigureRequest ),
    NV( GravityNotify ),
    NV( ResizeRequest ),
    NV( CirculateNotify ),
    NV( CirculateRequest ),
    NV( PropertyNotify ),
    NV( SelectionClear ),
    NV( SelectionRequest ),
    NV( SelectionNotify ),
    NV( ColormapNotify ),
    NV( ClientMessage ),
    NV( MappingNotify )
};


/***************************************
 ***************************************/

const char *
fli_get_xevent_name( const XEvent *xev )
{
      size_t i;
      static char buf[ 128 ];

      for ( i = KeyPress; i < LASTEvent; i++ )
      {
          if ( evname[ i ].type == xev->type )
          {
              fli_snprintf( buf, sizeof buf, "%s(0x%x)",
                            evname[ i ].name, xev->type );
              return buf;
          }
      }

      return "unknown event";
}


/***************************************
 ***************************************/

XEvent *
fl_print_xevent_name( const char *   where,
                      const XEvent * xev )
{
    size_t i,
           known;
    Window win = ( ( XAnyEvent * ) xev )->window;

    for ( i = KeyPress, known = 0; ! known && i < LASTEvent; i++ )
        if ( evname[ i ].type == xev->type )
        {
            fprintf( stderr, "%s Event (%d, win = %ld serial = %ld) %s ",
                     where ? where : "",
                     xev->type, win, ( ( XAnyEvent * ) xev)->serial,
                     evname[ i ].name );

            if ( xev->type == Expose )
                fprintf( stderr, "count = %d serial = %ld\n",
                         xev->xexpose.count, xev->xexpose.serial );
            else if ( xev->type == LeaveNotify || xev->type == EnterNotify )
                fprintf(stderr, "Mode %s\n", xev->xcrossing.mode == NotifyGrab ?
                        "Grab" :
                        ( xev->xcrossing.mode == NotifyNormal ?
                          "Normal" : "UnGrab" ) );
            else if ( xev->type == MotionNotify )
                fprintf(stderr, "Mode %s\n",
                        xev->xmotion.is_hint ? "Hint" : "Normal" );
            else if ( xev->type == ConfigureNotify )
                fprintf( stderr, "(x = %d y = %d w = %d h = %d) %s\n",
                         xev->xconfigure.x, xev->xconfigure.y,
                         xev->xconfigure.width, xev->xconfigure.height,
                         xev->xconfigure.send_event ? "Syn" : "Non-Syn" );
            else if ( xev->type == ButtonPress )
                fprintf( stderr, "button: %d\n", xev->xbutton.button );
            else if ( xev->type == ButtonRelease )
                fprintf( stderr, "button: %d\n", xev->xbutton.button );
            else
                fputc( '\n', stderr );
            known = 1;
        }

    if ( ! known )
        fprintf( stderr, "Unknown event %d, win = %ld\n", xev->type, win );

    return ( XEvent * ) xev;
}


/***************************************
 ***************************************/

XEvent *
fli_xevent_name( const char *   where,
                const XEvent * xev )
{

    if ( fli_cntl.debug >= 2 )
        fl_print_xevent_name( where, xev );

    return ( XEvent * ) xev;
}


/***************************************
 ***************************************/

static int
badwin_handler( Display *     dpy  FL_UNUSED_ARG,
                XErrorEvent * xev )
{
    if ( xev->type != BadWindow && xev->type != BadDrawable )
        M_err( "badwin_handler",
               "X error happened when expecting only BadWindow/Drawable\n" );
    return 0;
}


/***********************************************************************
 * Received an Expose event ev, see if next event is the same as the
 * the current one, drop it if it is, but we need consolidate all the
 * dirty rectangles into one.
 *
 * Must not block.
 ************************************************************************/

static void
compress_redraw( XEvent * ev )
{
    XEvent expose_ev;
    Window win = ev->xexpose.window;
    Region reg = XCreateRegion( );
    XRectangle rec;

    /* Original comment: this is theoretically not correct as we can't peek
       ahead and ignore the events in between, but it works in XForms as we
       always update the form size and position when dealing with Expose event.

       This has been changed a bit since 1.0.90: There was a problem with
       e.g. KDE or Gnome when they were set up to redraw also during resizing
       and the mouse was moved around rather fast. We collect now not only
       Expose events, compressing them to a single one, covering the combined
       area of all of them, but also ConfigureNotify events. If there was one
       or more ConfigureNotify events we put back the "consolidated" Expose
       event onto the event queue and return the last ConfigureNotify event
       instead of the original Expose event we got started with. This hope-
       fully is not only a solution that covers all cases but also keeps
       the numbers of redraws to a minimum. The only drawback is that in the
       do_interaction_step() function, handling the Expose event, one has to
       check if the area specified by the event isn't larger than the (new)
       size of the window and prune it if necessary.                  JTT */

    /* Collect all Expose events, combining their areas */

    do {
        rec.x      = ev->xexpose.x;
        rec.y      = ev->xexpose.y;
        rec.width  = ev->xexpose.width;
        rec.height = ev->xexpose.height;

        XUnionRectWithRegion( &rec, reg, reg );

    } while ( XCheckTypedWindowEvent( flx->display, win, Expose, ev ) );

    /* Set the area of the last events to that of the "consolidated" event
       and make a backup copy */

    XClipBox( reg, &rec );

    ev->xexpose.x = rec.x;
    ev->xexpose.y = rec.y;
    ev->xexpose.width = rec.width;
    ev->xexpose.height = rec.height;

    expose_ev = *ev;

    XDestroyRegion( reg );

    /* Now get all ConfigureNotify events */

    while ( XCheckTypedWindowEvent( flx->display, win, ConfigureNotify, ev ) )
        /*empty */ ;

    /* If there was at least one ConfigureNotify event put the "consolidated"
       Expose event back onto the event queue and return the last
       ConfigureNotify event we got, otherwise the Expose event itself.

       Since e.g. KDE and Gnome can send the ConfigureNotify event artificially
       to achieve an update of the display while resizing is still going on,
       the 'send_event' member of the XEvent structure might be set. On the
       other hand, in do_interaction_step(), where the events are handled,
       this member is checked for to get around a bug in mwm. So we got to
       reset it here to avoid the event getting flagged as spurious. This
       hopefully won't interfere with the mwm bug detection since it's for
       cases were a ConfigureNotify gets send, but no corresponding Expose
       events, and in this case we wouldn't have ended up here... */

    if ( ev->type == ConfigureNotify )
    {
        XPutBackEvent( flx->display, &expose_ev );
        ev->xconfigure.send_event = 0;
    }
}


/***************************************
 ***************************************/

static void
compress_motion( XEvent * xme )
{
    Window win = xme->xmotion.window;
    unsigned long evm = PointerMotionMask | ButtonMotionMask;

    if ( xme->type != MotionNotify )
        return;

    do
    {
#if FL_DEBUG >= ML_DEBUG
        M_info2( "compress_motion", "win = %ld (%d, %d) %s",
                 xme->xany.window, xme->xmotion.x, xme->xmotion.y,
                 xme->xmotion.is_hint ? "hint" : "" )
#endif
            /* empty */ ;
    } while ( XCheckWindowEvent( flx->display, win, evm, xme ) );

    if ( xme->xmotion.is_hint )
    {
        int ( *old )( Display *, XErrorEvent * );

        /* We must protect against BadWindow here, because we have only
           looked for Motion events, and there could be a Destroy event
           which makes the XQueryPointer fail as the window is deleted. */

        old = XSetErrorHandler( badwin_handler );
        fl_get_win_mouse( xme->xmotion.window,
                          &xme->xmotion.x, &xme->xmotion.y,
                          &xme->xmotion.state );
        XSetErrorHandler( old );
        xme->xmotion.is_hint = 0;
    }
}


/***************************************
 ***************************************/

void
fli_compress_event( XEvent *      xev,
                    unsigned long mask )
{
    if ( xev->type == Expose && mask & ExposureMask )
        compress_redraw( xev );
    else if (    xev->type == MotionNotify
              && mask & ( PointerMotionMask | ButtonMotionMask ) )
        compress_motion( xev );
}


/***************************************
 ***************************************/

int
fl_keysym_pressed( KeySym k )
{
    char kvec[ 32 ];
    KeyCode code;

    if ( ( code = XKeysymToKeycode( flx->display, k ) ) == NoSymbol )
    {
        M_warn( "fl_keysym_pressed", "Bad KeySym %d", ( int ) k );
        return 0;
    }

    XQueryKeymap( flx->display, kvec );
    return 1 & ( kvec[ code / 8 ] >> ( code & 7 ) );
}


/***************************************
 * Add an event
 ***************************************/

long
fl_addto_selected_xevent( Window win,
                          long   mask )
{
    XWindowAttributes xwa;

    XGetWindowAttributes( flx->display, win, &xwa );
    xwa.your_event_mask |= mask;

    /* On some SGI machines, 'your_event_mask' has bogus value 0x80??????,
       causing an X protocol error. Fix this here */

    xwa.your_event_mask &= AllEventsMask;
    XSelectInput( flx->display, win, xwa.your_event_mask );

    return xwa.your_event_mask;
}


/***************************************
 ***************************************/

long
fl_remove_selected_xevent( Window win,
                           long   mask )
{
    XWindowAttributes xwa;

    XGetWindowAttributes( flx->display, win, &xwa );
    xwa.your_event_mask &= ~mask;

    /* On some SGI machines 'your_event_mask' has bogus value of 0x80??????,
       causing an X protocol error. Fix this here */

    xwa.your_event_mask &= AllEventsMask;
    XSelectInput( flx->display, win, xwa.your_event_mask );

    return xwa.your_event_mask;
}


/*
 * Local variables:
 * tab-width: 4
 * indent-tabs-mode: nil
 * End:
 */