// $Id: tk.c 12965 2014-01-28 20:23:52Z arjenmarkus $
//
//	PLplot Tcl/Tk and Tcl-DP device drivers.
//	Should be broken up somewhat better to allow use of DP w/o X.
//
//	Maurice LeBrun
//	30-Apr-93
//
// Copyright (C) 2004  Maurice LeBrun
// Copyright (C) 2004  Joao Cardoso
// Copyright (C) 2004  Andrew Ross
//
// This file is part of PLplot.
//
// PLplot is free software; you can redistribute it and/or modify
// it under the terms of the GNU Library General Public License as published
// by the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// PLplot 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 Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with PLplot; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//

//
// #define DEBUG_ENTER
//

#define DEBUG

#include "plDevs.h"

#ifdef PLD_tk

#define NEED_PLDEBUG
#include "pltkd.h"
#include "pltcl.h"
#include "tcpip.h"
#include "drivers.h"
#include "metadefs.h"
#include "plevent.h"
#include <X11/keysym.h>

#if PL_HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <sys/types.h>
#if HAVE_SYS_WAIT_H
# include <sys/wait.h>
#endif
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>

#ifdef PLD_dp
# include <dp.h>
#endif

// Device info
PLDLLIMPEXP_DRIVER const char* plD_DEVICE_INFO_tk = "tk:Tcl/TK Window:1:tk:7:tk\n";


// Number of instructions to skip between updates

#define MAX_INSTR    100

// Pixels/mm

#define PHYSICAL    0                   // Enables physical scaling..

// These need to be distinguished since the handling is slightly different.

#define LOCATE_INVOKED_VIA_API       1
#define LOCATE_INVOKED_VIA_DRIVER    2

#define STR_LEN                      10
#define CMD_LEN                      100

// A handy command wrapper

#define tk_wr( code ) \
    if ( code ) { abort_session( pls, "Unable to write to PDFstrm" ); }

//--------------------------------------------------------------------------
// Function prototypes

// Driver entry and dispatch setup

void plD_dispatch_init_tk( PLDispatchTable *pdt );

void plD_init_tk( PLStream * );
void plD_line_tk( PLStream *, short, short, short, short );
void plD_polyline_tk( PLStream *, short *, short *, PLINT );
void plD_eop_tk( PLStream * );
void plD_bop_tk( PLStream * );
void plD_tidy_tk( PLStream * );
void plD_state_tk( PLStream *, PLINT );
void plD_esc_tk( PLStream *, PLINT, void * );
void plD_init_dp( PLStream *pls );

// various

static void  init( PLStream *pls );
static void  tk_start( PLStream *pls );
static void  tk_stop( PLStream *pls );
static void  tk_di( PLStream *pls );
static void  tk_fill( PLStream *pls );
static void  WaitForPage( PLStream *pls );
static void  CheckForEvents( PLStream *pls );
static void  HandleEvents( PLStream *pls );
static void  init_server( PLStream *pls );
static void  launch_server( PLStream *pls );
static void  flush_output( PLStream *pls );
static void  plwindow_init( PLStream *pls );
static void  link_init( PLStream *pls );
static void  GetCursor( PLStream *pls, PLGraphicsIn *ptr );
static void  tk_XorMod( PLStream *pls, PLINT *ptr );
static void  set_windowname( PLStream *pls );

// performs Tk-driver-specific initialization

static int   pltkdriver_Init( PLStream *pls );

// Tcl/TK utility commands

static void  tk_wait( PLStream *pls, const char * );
static void  abort_session( PLStream *pls, const char * );
static void  server_cmd( PLStream *pls, const char *, int );
static void  tcl_cmd( PLStream *pls, const char * );
static void  copybuf( PLStream *pls, const char *cmd );
static int   pltk_toplevel( Tk_Window *w, Tcl_Interp *interp );

static void  ProcessKey( PLStream *pls );
static void  ProcessButton( PLStream *pls );
static void  LocateKey( PLStream *pls );
static void  LocateButton( PLStream *pls );
static void  Locate( PLStream *pls );

// These are internal TCL commands

static int   Abort( ClientData, Tcl_Interp *, int, char ** );
static int   Plfinfo( ClientData, Tcl_Interp *, int, char ** );
static int   KeyEH( ClientData, Tcl_Interp *, int, char ** );
static int   ButtonEH( ClientData, Tcl_Interp *, int, char ** );
static int   LookupTkKeyEvent( PLStream *pls, Tcl_Interp *interp,
                               int argc, char **argv );
static int   LookupTkButtonEvent( PLStream *pls, Tcl_Interp *interp,
                                  int argc, char **argv );

static char   *drvoptcmd = NULL;  // tcl command from command line option parsing

static DrvOpt tk_options[] = { { "tcl_cmd", DRV_STR, &drvoptcmd, "Execute tcl command" },
                               { NULL,      DRV_INT, NULL,       NULL                  } };

void plD_dispatch_init_tk( PLDispatchTable *pdt )
{
#ifndef ENABLE_DYNDRIVERS
    pdt->pl_MenuStr = "Tcl/TK Window";
    pdt->pl_DevName = "tk";
#endif
    pdt->pl_type     = plDevType_Interactive;
    pdt->pl_seq      = 7;
    pdt->pl_init     = (plD_init_fp) plD_init_tk;
    pdt->pl_line     = (plD_line_fp) plD_line_tk;
    pdt->pl_polyline = (plD_polyline_fp) plD_polyline_tk;
    pdt->pl_eop      = (plD_eop_fp) plD_eop_tk;
    pdt->pl_bop      = (plD_bop_fp) plD_bop_tk;
    pdt->pl_tidy     = (plD_tidy_fp) plD_tidy_tk;
    pdt->pl_state    = (plD_state_fp) plD_state_tk;
    pdt->pl_esc      = (plD_esc_fp) plD_esc_tk;
}

//--------------------------------------------------------------------------
// plD_init_dp()
// plD_init_tk()
// init_tk()
//
// Initialize device.
// TK-dependent stuff done in tk_start().  You can set the display by
// calling plsfnam() with the display name as the (string) argument.
//--------------------------------------------------------------------------

void
plD_init_tk( PLStream *pls )
{
    pls->dp = 0;
    plParseDrvOpts( tk_options );
    init( pls );
}

void
plD_init_dp( PLStream *pls )
{
#ifdef PLD_dp
    pls->dp = 1;
#else
    fprintf( stderr, "The Tcl-DP driver hasn't been installed!\n" );
    pls->dp = 0;
#endif
    init( pls );
}

static void
tk_wr_header( PLStream *pls, const char *header )
{
    tk_wr( pdf_wr_header( pls->pdfs, header ) );
}

static void
init( PLStream *pls )
{
    U_CHAR c = (U_CHAR) INITIALIZE;
    TkDev  *dev;
    PLFLT  pxlx, pxly;
    int    xmin = 0;
    int    xmax = PIXELS_X - 1;
    int    ymin = 0;
    int    ymax = PIXELS_Y - 1;

    dbug_enter( "plD_init_tk" );

    pls->color         = 1;     // Is a color device
    pls->termin        = 1;     // Is an interactive terminal
    pls->dev_di        = 1;     // Handle driver interface commands
    pls->dev_flush     = 1;     // Handle our own flushes
    pls->dev_fill0     = 1;     // Handle solid fills
    pls->dev_fill1     = 1;     // Driver handles pattern fills
    pls->server_nokill = 1;     // don't kill if ^C
    pls->dev_xor       = 1;     // device support xor mode

// Activate plot buffer. To programmatically save a file we can't call
// plreplot(), but instead one must send a command to plserver. As there is
// no API call for this, the user must use the plserver "save/print" menu
// entries. Activating the plot buffer enables the normal
// plmkstrm/plcpstrm/plreplot/plend1 way of saving plots.
//
    pls->plbuf_write = 1;

// Specify buffer size if not yet set (can be changed by -bufmax option).
// A small buffer works best for socket communication

    if ( pls->bufmax == 0 )
    {
        if ( pls->dp )
            pls->bufmax = 450;
        else
            pls->bufmax = 3500;
    }

// Allocate and initialize device-specific data

    if ( pls->dev != NULL )
        free( (void *) pls->dev );

    pls->dev = calloc( 1, (size_t) sizeof ( TkDev ) );
    if ( pls->dev == NULL )
        plexit( "plD_init_tk: Out of memory." );

    dev = (TkDev *) pls->dev;

    dev->iodev = (PLiodev *) calloc( 1, (size_t) sizeof ( PLiodev ) );
    if ( dev->iodev == NULL )
        plexit( "plD_init_tk: Out of memory." );

    dev->exit_eventloop = FALSE;

// Variables used in querying plserver for events

    dev->instr     = 0;
    dev->max_instr = MAX_INSTR;

// Start interpreter and spawn server process

    tk_start( pls );

// Get ready for plotting

    dev->xold = PL_UNDEFINED;
    dev->yold = PL_UNDEFINED;

#if PHYSICAL
    pxlx = (double) PIXELS_X / dev->width * DPMM;
    pxly = (double) PIXELS_Y / dev->height * DPMM;
#else
    pxlx = (double) PIXELS_X / LPAGE_X;
    pxly = (double) PIXELS_Y / LPAGE_Y;
#endif

    plP_setpxl( pxlx, pxly );
    plP_setphy( xmin, xmax, ymin, ymax );

// Send init info

    tk_wr( pdf_wr_1byte( pls->pdfs, c ) );

// The header and version fields are useful when the client & server
// reside on different machines

    tk_wr_header( pls, PLSERV_HEADER );
    tk_wr_header( pls, PLSERV_VERSION );

    tk_wr_header( pls, "xmin" );
    tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) xmin ) );

    tk_wr_header( pls, "xmax" );
    tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) xmax ) );

    tk_wr_header( pls, "ymin" );
    tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) ymin ) );

    tk_wr_header( pls, "ymax" );
    tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) ymax ) );

    tk_wr_header( pls, "" );

// Write color map state info
    plD_state_tk( pls, PLSTATE_CMAP0 );
    plD_state_tk( pls, PLSTATE_CMAP1 );

// Good place to make sure the data transfer is working OK

    flush_output( pls );
}

//--------------------------------------------------------------------------
// plD_line_tk()
//
// Draw a line in the current color from (x1,y1) to (x2,y2).
//--------------------------------------------------------------------------

void
plD_line_tk( PLStream *pls, short x1, short y1, short x2, short y2 )
{
    U_CHAR  c;
    U_SHORT xy[4];
    TkDev   *dev = (TkDev *) pls->dev;

    CheckForEvents( pls );

    if ( x1 == dev->xold && y1 == dev->yold )
    {
        c = (U_CHAR) LINETO;
        tk_wr( pdf_wr_1byte( pls->pdfs, c ) );

        xy[0] = (U_SHORT) x2;
        xy[1] = (U_SHORT) y2;
        tk_wr( pdf_wr_2nbytes( pls->pdfs, xy, 2 ) );
    }
    else
    {
        c = (U_CHAR) LINE;
        tk_wr( pdf_wr_1byte( pls->pdfs, c ) );

        xy[0] = (U_SHORT) x1;
        xy[1] = (U_SHORT) y1;
        xy[2] = (U_SHORT) x2;
        xy[3] = (U_SHORT) y2;
        tk_wr( pdf_wr_2nbytes( pls->pdfs, xy, 4 ) );
    }
    dev->xold = x2;
    dev->yold = y2;

    if ( pls->pdfs->bp > (size_t) pls->bufmax )
        flush_output( pls );
}

//--------------------------------------------------------------------------
// plD_polyline_tk()
//
// Draw a polyline in the current color from (x1,y1) to (x2,y2).
//--------------------------------------------------------------------------

void
plD_polyline_tk( PLStream *pls, short *xa, short *ya, PLINT npts )
{
    U_CHAR c    = (U_CHAR) POLYLINE;
    TkDev  *dev = (TkDev *) pls->dev;

    CheckForEvents( pls );

    tk_wr( pdf_wr_1byte( pls->pdfs, c ) );
    tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) npts ) );

    tk_wr( pdf_wr_2nbytes( pls->pdfs, (U_SHORT *) xa, npts ) );
    tk_wr( pdf_wr_2nbytes( pls->pdfs, (U_SHORT *) ya, npts ) );

    dev->xold = xa[npts - 1];
    dev->yold = ya[npts - 1];

    if ( pls->pdfs->bp > (size_t) pls->bufmax )
        flush_output( pls );
}

//--------------------------------------------------------------------------
// plD_eop_tk()
//
// End of page.
// User must hit <RETURN> to continue.
//--------------------------------------------------------------------------

void
plD_eop_tk( PLStream *pls )
{
    U_CHAR c = (U_CHAR) EOP;

    dbug_enter( "plD_eop_tk" );

    tk_wr( pdf_wr_1byte( pls->pdfs, c ) );
    flush_output( pls );
    if ( !pls->nopause )
        WaitForPage( pls );
}

//--------------------------------------------------------------------------
// plD_bop_tk()
//
// Set up for the next page.
//--------------------------------------------------------------------------

void
plD_bop_tk( PLStream *pls )
{
    U_CHAR c    = (U_CHAR) BOP;
    TkDev  *dev = (TkDev *) pls->dev;

    dbug_enter( "plD_bop_tk" );

    dev->xold = PL_UNDEFINED;
    dev->yold = PL_UNDEFINED;
    pls->page++;
    tk_wr( pdf_wr_1byte( pls->pdfs, c ) );
}

//--------------------------------------------------------------------------
// plD_tidy_tk()
//
// Close graphics file
//--------------------------------------------------------------------------

void
plD_tidy_tk( PLStream *pls )
{
    TkDev *dev = (TkDev *) pls->dev;

    dbug_enter( "plD_tidy_tk" );

    if ( dev != NULL )
        tk_stop( pls );
}

//--------------------------------------------------------------------------
// plD_state_tk()
//
// Handle change in PLStream state (color, pen width, fill attribute, etc).
//--------------------------------------------------------------------------

void
plD_state_tk( PLStream *pls, PLINT op )
{
    U_CHAR c = (U_CHAR) CHANGE_STATE;
    int    i;

    dbug_enter( "plD_state_tk" );

    tk_wr( pdf_wr_1byte( pls->pdfs, c ) );
    tk_wr( pdf_wr_1byte( pls->pdfs, (U_CHAR) op ) );

    switch ( op )
    {
    case PLSTATE_WIDTH:
        tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) ( pls->width ) ) );
        break;

    case PLSTATE_COLOR0:
        tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) pls->icol0 ) );

        if ( pls->icol0 == PL_RGB_COLOR )
        {
            tk_wr( pdf_wr_1byte( pls->pdfs, pls->curcolor.r ) );
            tk_wr( pdf_wr_1byte( pls->pdfs, pls->curcolor.g ) );
            tk_wr( pdf_wr_1byte( pls->pdfs, pls->curcolor.b ) );
        }
        break;

    case PLSTATE_COLOR1:
        tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) pls->icol1 ) );
        break;

    case PLSTATE_FILL:
        tk_wr( pdf_wr_1byte( pls->pdfs, (U_CHAR) pls->patt ) );
        break;

    case PLSTATE_CMAP0:
        tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) pls->ncol0 ) );
        for ( i = 0; i < pls->ncol0; i++ )
        {
            tk_wr( pdf_wr_1byte( pls->pdfs, pls->cmap0[i].r ) );
            tk_wr( pdf_wr_1byte( pls->pdfs, pls->cmap0[i].g ) );
            tk_wr( pdf_wr_1byte( pls->pdfs, pls->cmap0[i].b ) );
        }
        break;

    case PLSTATE_CMAP1:
        tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) pls->ncol1 ) );
        for ( i = 0; i < pls->ncol1; i++ )
        {
            tk_wr( pdf_wr_1byte( pls->pdfs, pls->cmap1[i].r ) );
            tk_wr( pdf_wr_1byte( pls->pdfs, pls->cmap1[i].g ) );
            tk_wr( pdf_wr_1byte( pls->pdfs, pls->cmap1[i].b ) );
        }
        // Need to send over the control points too!
        tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) pls->ncp1 ) );
        for ( i = 0; i < pls->ncp1; i++ )
        {
            tk_wr( pdf_wr_ieeef( pls->pdfs, (float) pls->cmap1cp[i].h ) );
            tk_wr( pdf_wr_ieeef( pls->pdfs, (float) pls->cmap1cp[i].l ) );
            tk_wr( pdf_wr_ieeef( pls->pdfs, (float) pls->cmap1cp[i].s ) );
            tk_wr( pdf_wr_1byte( pls->pdfs, (U_CHAR) pls->cmap1cp[i].alt_hue_path ) );
        }
        break;
    }

    if ( pls->pdfs->bp > (size_t) pls->bufmax )
        flush_output( pls );
}

//--------------------------------------------------------------------------
// plD_esc_tk()
//
// Escape function.
// Functions:
//
//	PLESC_EXPOSE	Force an expose (just passes token)
//	PLESC_RESIZE	Force a resize (just passes token)
//	PLESC_REDRAW	Force a redraw
//	PLESC_FLUSH	Flush X event buffer
//	PLESC_FILL	Fill polygon
//	PLESC_EH	Handle events only
//	PLESC_XORMOD	Xor mode
//
//--------------------------------------------------------------------------

void
plD_esc_tk( PLStream *pls, PLINT op, void *ptr )
{
    U_CHAR c = (U_CHAR) ESCAPE;

    dbug_enter( "plD_esc_tk" );

    switch ( op )
    {
    case PLESC_DI:
        tk_wr( pdf_wr_1byte( pls->pdfs, c ) );
        tk_wr( pdf_wr_1byte( pls->pdfs, (U_CHAR) op ) );
        tk_di( pls );
        break;

    case PLESC_EH:
        tk_wr( pdf_wr_1byte( pls->pdfs, c ) );
        tk_wr( pdf_wr_1byte( pls->pdfs, (U_CHAR) op ) );
        HandleEvents( pls );
        break;

    case PLESC_FLUSH:
        tk_wr( pdf_wr_1byte( pls->pdfs, c ) );
        tk_wr( pdf_wr_1byte( pls->pdfs, (U_CHAR) op ) );
        flush_output( pls );
        break;

    case PLESC_FILL:
        tk_wr( pdf_wr_1byte( pls->pdfs, c ) );
        tk_wr( pdf_wr_1byte( pls->pdfs, (U_CHAR) op ) );
        tk_fill( pls );
        break;

    case PLESC_GETC:
        GetCursor( pls, (PLGraphicsIn *) ptr );
        break;

    case PLESC_XORMOD:
        tk_XorMod( pls, (PLINT *) ptr );
        break;

    default:
        tk_wr( pdf_wr_1byte( pls->pdfs, c ) );
        tk_wr( pdf_wr_1byte( pls->pdfs, (U_CHAR) op ) );
    }
}

//--------------------------------------------------------------------------
// tk_XorMod()
//
// enter (mod = 1) or leave (mod = 0) xor mode
//
//--------------------------------------------------------------------------

static void
tk_XorMod( PLStream *pls, PLINT *ptr )
{
    if ( *ptr != 0 )
        server_cmd( pls, "$plwidget cmd plxormod 1 st", 1 );
    else
        server_cmd( pls, "$plwidget cmd plxormod 0 st", 1 );
}


//--------------------------------------------------------------------------
// GetCursor()
//
// Waits for a graphics input event and returns coordinates.
//--------------------------------------------------------------------------

static void
GetCursor( PLStream *pls, PLGraphicsIn *ptr )
{
    TkDev        *dev = (TkDev *) pls->dev;
    PLGraphicsIn *gin = &( dev->gin );

// Initialize

    plGinInit( gin );
    dev->locate_mode = LOCATE_INVOKED_VIA_API;
    plD_esc_tk( pls, PLESC_FLUSH, NULL );
    server_cmd( pls, "$plwidget configure -xhairs on", 1 );

// Run event loop until a point is selected

    while ( gin->pX < 0 && dev->locate_mode )
    {
        Tk_DoOneEvent( 0 );
    }

// Clean up

    server_cmd( pls, "$plwidget configure -xhairs off", 1 );
    *ptr = *gin;
}

//--------------------------------------------------------------------------
// tk_di
//
// Process driver interface command.
// Just send the command to the remote PLplot library.
//--------------------------------------------------------------------------

static void
tk_di( PLStream *pls )
{
    TkDev *dev = (TkDev *) pls->dev;
    char  str[STR_LEN];

    dbug_enter( "tk_di" );

// Safety feature, should never happen

    if ( dev == NULL )
    {
        plabort( "tk_di: Illegal call to driver (not yet initialized)" );
        return;
    }

// Flush the buffer before proceeding

    flush_output( pls );

// Change orientation

    if ( pls->difilt & PLDI_ORI )
    {
        snprintf( str, STR_LEN, "%f", pls->diorot );
        Tcl_SetVar( dev->interp, "rot", str, 0 );

        server_cmd( pls, "$plwidget cmd plsetopt -ori $rot", 1 );
        pls->difilt &= ~PLDI_ORI;
    }

// Change window into plot space

    if ( pls->difilt & PLDI_PLT )
    {
        snprintf( str, STR_LEN, "%f", pls->dipxmin );
        Tcl_SetVar( dev->interp, "xl", str, 0 );
        snprintf( str, STR_LEN, "%f", pls->dipymin );
        Tcl_SetVar( dev->interp, "yl", str, 0 );
        snprintf( str, STR_LEN, "%f", pls->dipxmax );
        Tcl_SetVar( dev->interp, "xr", str, 0 );
        snprintf( str, STR_LEN, "%f", pls->dipymax );
        Tcl_SetVar( dev->interp, "yr", str, 0 );

        server_cmd( pls, "$plwidget cmd plsetopt -wplt $xl,$yl,$xr,$yr", 1 );
        pls->difilt &= ~PLDI_PLT;
    }

// Change window into device space

    if ( pls->difilt & PLDI_DEV )
    {
        snprintf( str, STR_LEN, "%f", pls->mar );
        Tcl_SetVar( dev->interp, "mar", str, 0 );
        snprintf( str, STR_LEN, "%f", pls->aspect );
        Tcl_SetVar( dev->interp, "aspect", str, 0 );
        snprintf( str, STR_LEN, "%f", pls->jx );
        Tcl_SetVar( dev->interp, "jx", str, 0 );
        snprintf( str, STR_LEN, "%f", pls->jy );
        Tcl_SetVar( dev->interp, "jy", str, 0 );

        server_cmd( pls, "$plwidget cmd plsetopt -mar $mar", 1 );
        server_cmd( pls, "$plwidget cmd plsetopt -a $aspect", 1 );
        server_cmd( pls, "$plwidget cmd plsetopt -jx $jx", 1 );
        server_cmd( pls, "$plwidget cmd plsetopt -jy $jy", 1 );
        pls->difilt &= ~PLDI_DEV;
    }

// Update view

    server_cmd( pls, "update", 1 );
    server_cmd( pls, "plw::update_view $plwindow", 1 );
}

//--------------------------------------------------------------------------
// tk_fill()
//
// Fill polygon described in points pls->dev_x[] and pls->dev_y[].
//--------------------------------------------------------------------------

static void
tk_fill( PLStream *pls )
{
    PLDev *dev = (PLDev *) pls->dev;

    dbug_enter( "tk_fill" );

    tk_wr( pdf_wr_2bytes( pls->pdfs, (U_SHORT) pls->dev_npts ) );

    tk_wr( pdf_wr_2nbytes( pls->pdfs, (U_SHORT *) pls->dev_x, pls->dev_npts ) );
    tk_wr( pdf_wr_2nbytes( pls->pdfs, (U_SHORT *) pls->dev_y, pls->dev_npts ) );

    dev->xold = PL_UNDEFINED;
    dev->yold = PL_UNDEFINED;
}

//--------------------------------------------------------------------------
// tk_start
//
// Create TCL interpreter and spawn off server process.
// Each stream that uses the tk driver gets its own interpreter.
//--------------------------------------------------------------------------

static void
tk_start( PLStream *pls )
{
    TkDev *dev = (TkDev *) pls->dev;

    dbug_enter( "tk_start" );

// Instantiate a TCL interpreter, and get rid of the exec command

    dev->interp = Tcl_CreateInterp();

    if ( Tcl_Init( dev->interp ) != TCL_OK )
    {
        fprintf( stderr, "%s\n", Tcl_GetStringResult( dev->interp ) );
        abort_session( pls, "Unable to initialize Tcl" );
    }

    tcl_cmd( pls, "rename exec {}" );

// Set top level window name & initialize

    set_windowname( pls );
    if ( pls->dp )
    {
        Tcl_SetVar( dev->interp, "dp", "1", TCL_GLOBAL_ONLY );
        dev->updatecmd = "dp_update";
    }
    else
    {
        Tcl_SetVar( dev->interp, "dp", "0", TCL_GLOBAL_ONLY );

        // tk_init needs this. Use pls->FileName first, then DISPLAY, then :0.0

        if ( pls->FileName != NULL )
            Tcl_SetVar2( dev->interp, "env", "DISPLAY", pls->FileName, TCL_GLOBAL_ONLY );
        else if ( getenv( "DISPLAY" ) != NULL )
            Tcl_SetVar2( dev->interp, "env", "DISPLAY", getenv( "DISPLAY" ), TCL_GLOBAL_ONLY ); // tk_init need this
        else
            Tcl_SetVar2( dev->interp, "env", "DISPLAY", "unix:0.0", TCL_GLOBAL_ONLY );          // tk_init need this

        dev->updatecmd = "update";
        if ( pltk_toplevel( &dev->w, dev->interp ) )
            abort_session( pls, "Unable to create top-level window" );
    }

// Eval startup procs

    if ( pltkdriver_Init( pls ) != TCL_OK )
    {
        abort_session( pls, "" );
    }

    if ( pls->debug )
        tcl_cmd( pls, "global auto_path; puts \"auto_path: $auto_path\"" );

// Other initializations.
// Autoloaded, so the user can customize it if desired

    tcl_cmd( pls, "plclient_init" );

// A different way to customize the interface.
// E.g. used by plrender to add a back page button.

    if ( drvoptcmd )
        tcl_cmd( pls, drvoptcmd );

// Initialize server process

    init_server( pls );

// By now we should be done with all autoloaded procs, so blow away
// the open command just in case security has been compromised

    tcl_cmd( pls, "rename open {}" );
    tcl_cmd( pls, "rename rename {}" );

// Initialize widgets

    plwindow_init( pls );

// Initialize data link

    link_init( pls );

    return;
}

//--------------------------------------------------------------------------
// tk_stop
//
// Normal termination & cleanup.
//--------------------------------------------------------------------------

static void
tk_stop( PLStream *pls )
{
    TkDev *dev = (TkDev *) pls->dev;

    dbug_enter( "tk_stop" );

// Safety check for out of control code

    if ( dev->pass_thru )
        return;

    dev->pass_thru = 1;

// Kill plserver

    tcl_cmd( pls, "plclient_link_end" );

// Wait for child process to complete

    if ( dev->child_pid )
    {
        waitpid( dev->child_pid, NULL, 0 );
//
//      problems if parent has not caught/ignore SIGCHLD. Returns -1 and errno=EINTR
//      if (waitpid(dev->child_pid, NULL, 0) != dev->child_pid)
//          fprintf(stderr, "tk_stop: waidpid error");
//
    }

// Blow away interpreter

    Tcl_DeleteInterp( dev->interp );
    dev->interp = NULL;

// Free up memory and other miscellanea

    pdf_close( pls->pdfs );
    if ( dev->iodev != NULL )
    {
        if ( dev->iodev->file != NULL )
            plCloseFile( pls );

        free( (void *) dev->iodev );
    }
    free_mem( dev->cmdbuf );
}

//--------------------------------------------------------------------------
// abort_session
//
// Terminates with an error.
// Cleanup is done here, and once pls->level is cleared the driver will
// never be called again.
//--------------------------------------------------------------------------

static void
abort_session( PLStream *pls, const char *msg )
{
    TkDev *dev = (TkDev *) pls->dev;

    dbug_enter( "abort_session" );

// Safety check for out of control code

    if ( dev->pass_thru )
        return;

    tk_stop( pls );
    pls->level = 0;

    plexit( msg );
}

//--------------------------------------------------------------------------
// pltkdriver_Init
//
// Performs PLplot/TK driver-specific Tcl initialization.
//--------------------------------------------------------------------------

static int
pltkdriver_Init( PLStream *pls )
{
    TkDev      *dev    = (TkDev *) pls->dev;
    Tcl_Interp *interp = (Tcl_Interp *) dev->interp;

//
// Call the init procedures for included packages.  Each call should
// look like this:
//
// if (Mod_Init(interp) == TCL_ERROR) {
//     return TCL_ERROR;
// }
//
// where "Mod" is the name of the module.
//

    if ( Tcl_Init( interp ) == TCL_ERROR )
    {
        return TCL_ERROR;
    }
#ifdef PLD_dp
    if ( pls->dp )
    {
        if ( Tdp_Init( interp ) == TCL_ERROR )
        {
            return TCL_ERROR;
        }
    }
#endif

//
// Call Tcl_CreateCommand for application-specific commands, if
// they weren't already created by the init procedures called above.
//

    Tcl_CreateCommand( interp, "wait_until", (Tcl_CmdProc *) plWait_Until,
        (ClientData) NULL, (Tcl_CmdDeleteProc *) NULL );

#ifdef PLD_dp
    if ( pls->dp )
    {
        Tcl_CreateCommand( interp, "host_id", (Tcl_CmdProc *) plHost_ID,
            (ClientData) NULL, (Tcl_CmdDeleteProc *) NULL );
    }
#endif

    Tcl_CreateCommand( interp, "abort", (Tcl_CmdProc *) Abort,
        (ClientData) pls, (Tcl_CmdDeleteProc *) NULL );

    Tcl_CreateCommand( interp, "plfinfo", (Tcl_CmdProc *) Plfinfo,
        (ClientData) pls, (Tcl_CmdDeleteProc *) NULL );

    Tcl_CreateCommand( interp, "keypress", (Tcl_CmdProc *) KeyEH,
        (ClientData) pls, (Tcl_CmdDeleteProc *) NULL );

    Tcl_CreateCommand( interp, "buttonpress", (Tcl_CmdProc *) ButtonEH,
        (ClientData) pls, (Tcl_CmdDeleteProc *) NULL );

// Set some relevant interpreter variables

    if ( !pls->dp )
        tcl_cmd( pls, "set client_name [winfo name .]" );

    if ( pls->server_name != NULL )
        Tcl_SetVar( interp, "server_name", pls->server_name, 0 );

    if ( pls->server_host != NULL )
        Tcl_SetVar( interp, "server_host", pls->server_host, 0 );

    if ( pls->server_port != NULL )
        Tcl_SetVar( interp, "server_port", pls->server_port, 0 );

// Set up auto_path

    if ( pls_auto_path( interp ) == TCL_ERROR )
        return TCL_ERROR;

    return TCL_OK;
}

//--------------------------------------------------------------------------
// init_server
//
// Starts interaction with server process, launching it if necessary.
//
// There are several possibilities we must account for, depending on the
// message protocol, input flags, and whether plserver is already running
// or not.  From the point of view of the code, they are:
//
//    1. Driver: tk
//	 Flags: <none>
//	 Meaning: need to start up plserver (same host)
//	 Actions: fork plserver, passing it our TK main window name
//		  for communication.  Once started, plserver will send
//		  back its main window name.
//
//    2. Driver: dp
//	 Flags: <none>
//	 Meaning: need to start up plserver (same host)
//	 Actions: fork plserver, passing it our Tcl-DP communication port
//		  for communication. Once started, plserver will send
//		  back its created message port number.
//
//    3. Driver: tk
//	 Flags: -server_name
//	 Meaning: plserver already running (same host)
//	 Actions: communicate to plserver our TK main window name.
//
//    4. Driver: dp
//	 Flags: -server_port
//	 Meaning: plserver already running (same host)
//	 Actions: communicate to plserver our Tcl-DP port number.
//
//    5. Driver: dp
//	 Flags: -server_host
//	 Meaning: need to start up plserver (remote host)
//	 Actions: rsh (remsh) plserver, passing it our host ID and Tcl-DP
//		  port for communication. Once started, plserver will send
//		  back its created message port number.
//
//    6. Driver: dp
//	 Flags: -server_host -server_port
//	 Meaning: plserver already running (remote host)
//	 Actions: communicate to remote plserver our host ID and Tcl-DP
//		  port number.
//
// For a bit more flexibility, you can change the name of the process
// invoked from "plserver" to something else, using the -plserver flag.
//
// The startup procedure involves some rather involved handshaking between
// client and server.  This is made easier by using the Tcl variables:
//
//	client_host client_port server_host server_port
//
// when using Tcl-DP sends and
//
//	client_name server_name
//
// when using TK sends.  The global Tcl variables
//
//	client server
//
// are used as the defining identification for the client and server
// respectively -- they denote the main window name when TK sends are used
// and the respective process's listening socket when Tcl-DP sends are
// used.  Note that in the former case, $client is just the same as
// $client_name.  In addition, since the server may need to communicate
// with many different client processes, every command to the server
// contains the sender's client id (so it knows how to report back if
// necessary).  Thus the Tk driver's interpreter must know both $server as
// well as $client.  It is most convenient to set $client from the server,
// as a way to signal that communication has been set up and it is safe to
// proceed.
//
// Often it is necessary to use constructs such as [list $server] instead
// of just $server.  This occurs since you could have multiple copies
// running on the display (resulting in names of the form "plserver #2",
// etc).  Embedding such a string in a "[list ...]" construct prevents the
// string from being interpreted as two separate strings.
//--------------------------------------------------------------------------

static void
init_server( PLStream *pls )
{
    int server_exists = 0;

    dbug_enter( "init_server" );

    pldebug( "init_server", "%s -- PID: %d, PGID: %d, PPID: %d\n",
        __FILE__, (int) getpid(), (int) getpgrp(), (int) getppid() );

// If no means of communication provided, need to launch plserver

    if ( ( !pls->dp && pls->server_name != NULL ) ||
         ( pls->dp && pls->server_port != NULL ) )
        server_exists = 1;

// So launch it

    if ( !server_exists )
        launch_server( pls );

// Set up communication channel to server

    if ( pls->dp )
    {
        tcl_cmd( pls,
            "set server [dp_MakeRPCClient $server_host $server_port]" );
    }
    else
    {
        tcl_cmd( pls, "set server $server_name" );
    }

// If server didn't need launching, contact it here

    if ( server_exists )
        tcl_cmd( pls, "plclient_link_init" );
}

//--------------------------------------------------------------------------
// launch_server
//
// Launches plserver, locally or remotely.
//--------------------------------------------------------------------------

static void
launch_server( PLStream *pls )
{
    TkDev      *dev = (TkDev *) pls->dev;
    const char *argv[20];
    char       *plserver_exec = NULL, *ptr;
    char       *tmp           = NULL;
    int        i;

    dbug_enter( "launch_server" );

    if ( pls->plserver == NULL )
        pls->plserver = plstrdup( "plserver" );

// Build argument list

    i = 0;

// If we're doing a rsh, need to set up its arguments first.

    if ( pls->dp && pls->server_host != NULL )
    {
        argv[i++] = pls->server_host;   // Host name for rsh

        if ( pls->user != NULL )
        {
            argv[i++] = "-l";
            argv[i++] = pls->user;      // User name on remote node
        }
    }

// The invoked executable name comes next

    argv[i++] = pls->plserver;

// The rest are arguments to plserver

    argv[i++] = "-child";               // Tell plserver its ancestry

    argv[i++] = "-e";                   // Startup script
    argv[i++] = "plserver_init";

// aaahhh. This is it! Without the next statements, control is either
// in tk or octave, because tcl/tk was in interative mode (I think).
// This had the inconvenient of having to press the enter key or cliking a
// mouse button in the plot window after every plot.
//
// This couldn't be done with
//	Tcl_SetVar(dev->interp, "tcl_interactive", "0", TCL_GLOBAL_ONLY);
// after plserver has been launched? It doesnt work, hoewever.
// Tk_CreateFileHandler (0, TK_READABLE, NULL, 0) doesnt work also
//

    argv[i++] = "-file";                        // Startup file
    if ( pls->tk_file )
        argv[i++] = pls->tk_file;
    else
        argv[i++] = "/dev/null";


//
// Give interpreter the base name of the plwindow.
// Useful to know the interpreter name
//

    if ( pls->plwindow != NULL )
    {
        char *t;
        argv[i++] = "-name";                       // plserver name
        tmp       = plstrdup( pls->plwindow + 1 ); // get rid of the initial dot
        argv[i++] = tmp;
        if ( ( t = strchr( tmp, '.' ) ) != NULL )
            *t = '\0';                  // and keep only the base name
    }
    else
    {
        argv[i++] = "-name";            // plserver name
        argv[i++] = pls->program;
    }

    if ( pls->auto_path != NULL )
    {
        argv[i++] = "-auto_path";       // Additional directory(s)
        argv[i++] = pls->auto_path;     // to autoload
    }

    if ( pls->geometry != NULL )
    {
        argv[i++] = "-geometry";        // Top level window geometry
        argv[i++] = pls->geometry;
    }

// If communicating via Tcl-DP, specify communications port id
// If communicating via TK send, specify main window name

    if ( pls->dp )
    {
        argv[i++] = "-client_host";
        argv[i++] = Tcl_GetVar( dev->interp, "client_host", TCL_GLOBAL_ONLY );

        argv[i++] = "-client_port";
        argv[i++] = Tcl_GetVar( dev->interp, "client_port", TCL_GLOBAL_ONLY );

        if ( pls->user != NULL )
        {
            argv[i++] = "-l";
            argv[i++] = pls->user;
        }
    }
    else
    {
        argv[i++] = "-client_name";
        argv[i++] = Tcl_GetVar( dev->interp, "client_name", TCL_GLOBAL_ONLY );
    }

// The display absolutely must be set if invoking a remote server (by rsh)
// Use the DISPLAY environmental, if set.  Otherwise use the remote host.

    if ( pls->FileName != NULL )
    {
        argv[i++] = "-display";
        argv[i++] = pls->FileName;
    }
    else if ( pls->dp && pls->server_host != NULL )
    {
        argv[i++] = "-display";
        if ( ( ptr = getenv( "DISPLAY" ) ) != NULL )
            argv[i++] = ptr;
        else
            argv[i++] = "unix:0.0";
    }

// Add terminating null

    argv[i++] = NULL;
#ifdef DEBUG
    if ( pls->debug )
    {
        int j;
        fprintf( stderr, "argument list: \n   " );
        for ( j = 0; j < i; j++ )
            fprintf( stderr, "%s ", argv[j] );
        fprintf( stderr, "\n" );
    }
#endif

// Start server process
// It's a fork/rsh if on a remote machine

    if ( pls->dp && pls->server_host != NULL )
    {
        if ( ( dev->child_pid = fork() ) < 0 )
        {
            abort_session( pls, "Unable to fork server process" );
        }
        else if ( dev->child_pid == 0 )
        {
            fprintf( stderr, "Starting up %s on node %s\n", pls->plserver,
                pls->server_host );

            if ( execvp( "rsh", (char * const *) argv ) )
            {
                perror( "Unable to exec server process" );
                _exit( 1 );
            }
        }
    }

// Running locally, so its a fork/exec

    else
    {
        plserver_exec = plFindCommand( pls->plserver );
        if ( ( plserver_exec == NULL ) || ( dev->child_pid = fork() ) < 0 )
        {
            abort_session( pls, "Unable to fork server process" );
        }
        else if ( dev->child_pid == 0 )
        {
            // Don't kill plserver on a ^C if pls->server_nokill is set

            if ( pls->server_nokill )
            {
                sigset_t set;
                sigemptyset( &set );
                sigaddset( &set, SIGINT );
                if ( sigprocmask( SIG_BLOCK, &set, 0 ) < 0 )
                    fprintf( stderr, "PLplot: sigprocmask failure\n" );
            }

            pldebug( "launch_server", "Starting up %s\n", plserver_exec );
            if ( execv( plserver_exec, (char * const *) argv ) )
            {
                fprintf( stderr, "Unable to exec server process.\n" );
                _exit( 1 );
            }
        }
        free_mem( plserver_exec );
    }
    free_mem( tmp );

// Wait for server to set up return communication channel

    tk_wait( pls, "[info exists client]" );
}

//--------------------------------------------------------------------------
// plwindow_init
//
// Configures the widget hierarchy we are sending the data stream to.
//
// If a widget name (identifying the actual widget or a container widget)
// hasn't been supplied already we assume it needs to be created.
//
// In order to achieve maximum flexibility, the PLplot tk driver requires
// only that certain TCL procs must be defined in the server interpreter.
// These can be used to set up the desired widget configuration.  The procs
// invoked from this driver currently include:
//
//    $plw_create_proc		Creates the widget environment
//    $plw_start_proc		Does any remaining startup necessary
//    $plw_end_proc		Prepares for shutdown
//    $plw_flash_proc		Invoked when waiting for page advance
//
// Since all of these are interpreter variables, they can be trivially
// changed by the user.
//
// Each of these utility procs is called with a widget name ($plwindow)
// as argument.  "plwindow" is set from the value of pls->plwindow, and
// if null is generated from the name of the client main window (to
// ensure uniqueness).  $plwindow usually indicates the container frame
// for the actual PLplot widget, but can be arbitrary -- as long as the
// usage in all the TCL procs is consistent.
//
// In order that the TK driver be able to invoke the actual PLplot
// widget, the proc "$plw_create_proc" deposits the widget name in the local
// interpreter variable "plwidget".
//--------------------------------------------------------------------------

static void
plwindow_init( PLStream *pls )
{
    TkDev        *dev = (TkDev *) pls->dev;
    char         command[CMD_LEN];
    unsigned int bg;
    char         *tmp;
    int          i, n;

    dbug_enter( "plwindow_init" );

    // Set tcl plwindow variable to be pls->plwindow with a . prepended and
    // and with ' ' replaced by '_' and all other '.' by '_' to avoid
    // quoting and bad window name problems. Also avoid name starting with
    // an upper case letter.
    n   = (int) strlen( pls->plwindow ) + 1;
    tmp = (char *) malloc( sizeof ( char ) * (size_t) ( n + 1 ) );
    sprintf( tmp, ".%s", pls->plwindow );
    for ( i = 1; i < n; i++ )
    {
        if ( ( tmp[i] == ' ' ) || ( tmp[i] == '.' ) )
            tmp[i] = '_';
    }
    if ( isupper( tmp[1] ) )
        tmp[1] = tolower( tmp[1] );
    Tcl_SetVar( dev->interp, "plwindow", tmp, 0 );
    free( tmp );

// Create the plframe widget & anything else you want with it.

    server_cmd( pls,
        "$plw_create_proc $plwindow [list $client]", 1 );

    tk_wait( pls, "[info exists plwidget]" );

// Now we should have the actual PLplot widget name in $plwidget
// Configure remote PLplot stream.

// Configure background color if anything other than black
// The default color is handled from a resource setting in plconfig.tcl

    bg = (unsigned int) ( pls->cmap0[0].b | ( pls->cmap0[0].g << 8 ) | ( pls->cmap0[0].r << 16 ) );
    if ( bg > 0 )
    {
        snprintf( command, CMD_LEN, "$plwidget configure -plbg #%06x", bg );
        server_cmd( pls, command, 0 );
    }

// nopixmap option

    if ( pls->nopixmap )
        server_cmd( pls, "$plwidget cmd plsetopt -nopixmap", 0 );

// debugging

    if ( pls->debug )
        server_cmd( pls, "$plwidget cmd plsetopt -debug", 0 );

// double buffering

    if ( pls->db )
        server_cmd( pls, "$plwidget cmd plsetopt -db", 0 );

// color map options

    if ( pls->ncol0 )
    {
        snprintf( command, CMD_LEN, "$plwidget cmd plsetopt -ncol0 %d", pls->ncol0 );
        server_cmd( pls, command, 0 );
    }

    if ( pls->ncol1 )
    {
        snprintf( command, CMD_LEN, "$plwidget cmd plsetopt -ncol1 %d", pls->ncol1 );
        server_cmd( pls, command, 0 );
    }

// Start up remote PLplot

    server_cmd( pls, "$plw_start_proc $plwindow", 1 );
    tk_wait( pls, "[info exists widget_is_ready]" );
}

//--------------------------------------------------------------------------
// set_windowname
//
// Set up top level window name.  Use pls->program, modified appropriately.
//--------------------------------------------------------------------------

static void
set_windowname( PLStream *pls )
{
    const char *pname;
    int        i;
    size_t     maxlen;

    // Set to "plclient" if not initialized via plargs or otherwise

    if ( pls->program == NULL )
        pls->program = plstrdup( "plclient" );

    // Eliminate any leading path specification

    pname = strrchr( pls->program, '/' );
    if ( pname )
        pname++;
    else
        pname = pls->program;

    if ( pls->plwindow == NULL ) // dont override -plwindow cmd line option
    {
        maxlen        = strlen( pname ) + 10;
        pls->plwindow = (char *) malloc( maxlen * sizeof ( char ) );

        // Allow for multiple widgets created by multiple streams

        if ( pls->ipls == 0 )
            snprintf( pls->plwindow, maxlen, ".%s", pname );
        else
            snprintf( pls->plwindow, maxlen, ".%s_%d", pname, (int) pls->ipls );

        // Replace any ' 's with '_'s to avoid quoting problems.
        // Replace any '.'s (except leading) with '_'s to avoid bad window names.

        for ( i = 0; i < (int) strlen( pls->plwindow ); i++ )
        {
            if ( pls->plwindow[i] == ' ' )
                pls->plwindow[i] = '_';
            if ( i == 0 )
                continue;
            if ( pls->plwindow[i] == '.' )
                pls->plwindow[i] = '_';
        }
    }
}

//--------------------------------------------------------------------------
// link_init
//
// Initializes the link between the client and the PLplot widget for
// data transfer.  Defaults to a FIFO when the TK driver is selected and
// a socket when the DP driver is selected.
//--------------------------------------------------------------------------

static void
link_init( PLStream *pls )
{
    TkDev      *dev     = (TkDev *) pls->dev;
    PLiodev    *iodev   = (PLiodev *) dev->iodev;
    size_t     bufmax   = (size_t) ( pls->bufmax * 1.2 );
    const char *dirname = NULL;

    dbug_enter( "link_init" );

// Create FIFO for data transfer to the plframe widget

    if ( !pls->dp )
    {
        // This uses the pl_create_tempfifo function to create
        // the fifo in a safe manner by first creating a private
        // temporary directory.
        iodev->fileName = pl_create_tempfifo( (const char **) &iodev->fileName, &dirname );
        if ( dirname == NULL || iodev->fileName == NULL )
            abort_session( pls, "mkfifo error" );

        // Tell plframe widget to open FIFO (for reading).

        Tcl_SetVar( dev->interp, "fifoname", iodev->fileName, 0 );
        server_cmd( pls, "$plwidget openlink fifo $fifoname", 1 );

        // Open the FIFO for writing
        // This will block until the server opens it for reading

        if ( ( iodev->fd = open( iodev->fileName, O_WRONLY ) ) == -1 )
            abort_session( pls, "Error opening fifo for write" );

        // Create stream interface (C file handle) to FIFO

        iodev->type     = 0;
        iodev->typeName = "fifo";
        iodev->file     = fdopen( iodev->fd, "wb" );

// Unlink FIFO so that it isn't left around if program crashes.
// This also ensures no other program can mess with it.

        if ( unlink( iodev->fileName ) == -1 )
            abort_session( pls, "Error removing fifo" );
        free( (void *) iodev->fileName );
        iodev->fileName = NULL;
        if ( rmdir( dirname ) == -1 )
            abort_session( pls, "Error removing temporary directory" );
        free( (void *) dirname );
    }

// Create socket for data transfer to the plframe widget

    else
    {
        iodev->type     = 1;
        iodev->typeName = "socket";
        tcl_cmd( pls, "plclient_dp_init" );
        iodev->fileHandle = Tcl_GetVar( dev->interp, "data_sock", 0 );

        if ( Tcl_GetOpenFile( dev->interp, iodev->fileHandle,
                 0, 1, ( ClientData ) & iodev->file ) != TCL_OK )
        {
            fprintf( stderr, "Cannot get file info:\n\t %s\n",
                Tcl_GetStringResult( dev->interp ) );
            abort_session( pls, "" );
        }
        iodev->fd = fileno( iodev->file );
    }

// Create data buffer

    pls->pdfs = pdf_bopen( NULL, (size_t) bufmax );
}

//--------------------------------------------------------------------------
// WaitForPage()
//
// Waits for a page advance.
//--------------------------------------------------------------------------

static void
WaitForPage( PLStream *pls )
{
    TkDev *dev = (TkDev *) pls->dev;

    dbug_enter( "WaitForPage" );

    while ( !dev->exit_eventloop )
    {
        Tk_DoOneEvent( 0 );
    }
    dev->exit_eventloop = 0;
}

//--------------------------------------------------------------------------
// CheckForEvents()
//
// A front-end to HandleEvents(), which is only called if certain conditions
// are satisfied:
//
// - only check for events and process them every dev->max_instr times this
//   function is called (good for performance since performing an update is
//   a nontrivial performance hit).
//--------------------------------------------------------------------------

static void
CheckForEvents( PLStream *pls )
{
    TkDev *dev = (TkDev *) pls->dev;

    if ( ++dev->instr % dev->max_instr == 0 )
    {
        dev->instr = 0;
        HandleEvents( pls );
    }
}

//--------------------------------------------------------------------------
// HandleEvents()
//
// Just a front-end to the update command, for use when not actually waiting
// for an event but only checking the event queue.
//--------------------------------------------------------------------------

static void
HandleEvents( PLStream *pls )
{
    TkDev *dev = (TkDev *) pls->dev;

    dbug_enter( "HandleEvents" );

    Tcl_VarEval( dev->interp, dev->updatecmd, (char **) NULL );
}

//--------------------------------------------------------------------------
// flush_output()
//
// Sends graphics instructions to the {FIFO|socket} via a packet send.
//
// The packet i/o routines are modified versions of the ones from the
// Tcl-DP package.  They have been altered to take a pointer to a PDFstrm
// struct, and read-to or write-from pdfs->buffer.  The length of the
// buffer is stored in pdfs->bp (the original Tcl-DP routine assumes the
// message is character data and uses strlen).  Also, they can
// send/receive from either a fifo or a socket.
//--------------------------------------------------------------------------

static void
flush_output( PLStream *pls )
{
    TkDev   *dev  = (TkDev *) pls->dev;
    PDFstrm *pdfs = (PDFstrm *) pls->pdfs;

    dbug_enter( "flush_output" );

    HandleEvents( pls );

// Send packet -- plserver filehandler will be invoked automatically.

    if ( pdfs->bp > 0 )
    {
#ifdef DEBUG_ENTER
        pldebug( "flush_output", "%s: Flushing buffer, bytes = %ld\n",
            __FILE__, pdfs->bp );
#endif
        if ( pl_PacketSend( dev->interp, dev->iodev, pls->pdfs ) )
        {
            fprintf( stderr, "Packet send failed:\n\t %s\n",
                Tcl_GetStringResult( dev->interp ) );
            abort_session( pls, "" );
        }
        pdfs->bp = 0;
    }
}

//--------------------------------------------------------------------------
// Abort
//
// Just a TCL front-end to abort_session().
//--------------------------------------------------------------------------

static int
Abort( ClientData clientData, Tcl_Interp *PL_UNUSED( interp ), int PL_UNUSED( argc ), char **PL_UNUSED( argv ) )
{
    PLStream *pls = (PLStream *) clientData;

    dbug_enter( "Abort" );

    abort_session( pls, "" );
    return TCL_OK;
}

//--------------------------------------------------------------------------
// Plfinfo
//
// Sends info about the server plframe.  Usually issued after some
// modification to the plframe is made by the user, such as a resize.
//--------------------------------------------------------------------------

static int
Plfinfo( ClientData clientData, Tcl_Interp *interp, int argc, char **argv )
{
    PLStream *pls   = (PLStream *) clientData;
    TkDev    *dev   = (TkDev *) pls->dev;
    int      result = TCL_OK;

    dbug_enter( "Plfinfo" );

    if ( argc < 3 )
    {
        Tcl_AppendResult( interp, "wrong # args: should be \"",
            " plfinfo wx wy\"", (char *) NULL );
        result = TCL_ERROR;
    }
    else
    {
        dev->width  = (unsigned int) atoi( argv[1] );
        dev->height = (unsigned int) atoi( argv[2] );
#if PHYSICAL
        {
            PLFLT pxlx = (double) PIXELS_X / dev->width * DPMM;
            PLFLT pxly = (double) PIXELS_Y / dev->height * DPMM;
            plP_setpxl( pxlx, pxly );
        }
#endif
    }

    return result;
}

//--------------------------------------------------------------------------
// KeyEH()
//
// This TCL command handles keyboard events.
//--------------------------------------------------------------------------

static int
KeyEH( ClientData clientData, Tcl_Interp *interp, int argc, char **argv )
{
    PLStream *pls = (PLStream *) clientData;
    TkDev    *dev = (TkDev *) pls->dev;
    int      result;

    dbug_enter( "KeyEH" );

    if ( ( result = LookupTkKeyEvent( pls, interp, argc, argv ) ) != TCL_OK )
        return result;

    if ( dev->locate_mode )
        LocateKey( pls );
    else
        ProcessKey( pls );

    return result;
}

//--------------------------------------------------------------------------
// ButtonEH()
//
// This TCL command handles button events.
//--------------------------------------------------------------------------

static int
ButtonEH( ClientData clientData, Tcl_Interp *interp, int argc, char **argv )
{
    PLStream *pls = (PLStream *) clientData;
    TkDev    *dev = (TkDev *) pls->dev;
    int      result;

    dbug_enter( "ButtonEH" );

    if ( ( result = LookupTkButtonEvent( pls, interp, argc, argv ) ) != TCL_OK )
        return result;

    if ( dev->locate_mode )
        LocateButton( pls );
    else
        ProcessButton( pls );

    return result;
}

//--------------------------------------------------------------------------
// LookupTkKeyEvent()
//
// Fills in the PLGraphicsIn from a Tk KeyEvent.
//
// Contents of argv array:
//	command name
//	keysym value
//	keysym state
//	absolute x coordinate of cursor
//	absolute y coordinate of cursor
//	relative x coordinate (normalized to [0.0 1.0])
//	relative y coordinate (normalized to [0.0 1.0])
//	keysym name
//	ASCII equivalent (optional)
//
// Note that the keysym name is only used for debugging, and the string is
// not always passed (i.e. the character may not have an ASCII
// representation).
//--------------------------------------------------------------------------

static int
LookupTkKeyEvent( PLStream *pls, Tcl_Interp *interp, int argc, char **argv )
{
    TkDev        *dev = (TkDev *) pls->dev;
    PLGraphicsIn *gin = &( dev->gin );
    char         *keyname;

    dbug_enter( "LookupTkKeyEvent" );

    if ( argc < 8 )
    {
        Tcl_AppendResult( interp, "wrong # args: should be \"",
            argv[0], " key-value state pX pY dX dY key-name ?ascii-value?\"",
            (char *) NULL );
        return TCL_ERROR;
    }

    gin->keysym = (unsigned int) atol( argv[1] );
    gin->state  = (unsigned int) atol( argv[2] );
    gin->pX     = atoi( argv[3] );
    gin->pY     = atoi( argv[4] );
    gin->dX     = atof( argv[5] );
    gin->dY     = atof( argv[6] );

    keyname = argv[7];

    gin->string[0] = '\0';
    if ( argc > 8 )
    {
        gin->string[0] = argv[8][0];
        gin->string[1] = '\0';
    }

// Fix up keysym value -- see notes in xwin.c about key representation

    switch ( gin->keysym )
    {
    case XK_BackSpace:
    case XK_Tab:
    case XK_Linefeed:
    case XK_Return:
    case XK_Escape:
    case XK_Delete:
        gin->keysym &= 0xFF;
        break;
    }

    pldebug( "LookupTkKeyEvent",
        "KeyEH: stream: %d, Keyname %s, hex %x, ASCII: %s\n",
        (int) pls->ipls, keyname, (unsigned int) gin->keysym, gin->string );

    return TCL_OK;
}

//--------------------------------------------------------------------------
// LookupTkButtonEvent()
//
// Fills in the PLGraphicsIn from a Tk ButtonEvent.
//
// Contents of argv array:
//	command name
//	button number
//	state (decimal string)
//	absolute x coordinate
//	absolute y coordinate
//	relative x coordinate (normalized to [0.0 1.0])
//	relative y coordinate (normalized to [0.0 1.0])
//--------------------------------------------------------------------------

static int
LookupTkButtonEvent( PLStream *pls, Tcl_Interp *interp, int argc, char **argv )
{
    TkDev        *dev = (TkDev *) pls->dev;
    PLGraphicsIn *gin = &( dev->gin );

    dbug_enter( "LookupTkButtonEvent" );

    if ( argc != 7 )
    {
        Tcl_AppendResult( interp, "wrong # args: should be \"",
            argv[0], " button-number state pX pY dX dY\"", (char *) NULL );
        return TCL_ERROR;
    }

    gin->button = (unsigned int) atol( argv[1] );
    gin->state  = (unsigned int) atol( argv[2] );
    gin->pX     = atoi( argv[3] );
    gin->pY     = atoi( argv[4] );
    gin->dX     = atof( argv[5] );
    gin->dY     = atof( argv[6] );
    gin->keysym = 0x20;

    pldebug( "LookupTkButtonEvent",
        "button %d, state %d, pX: %d, pY: %d, dX: %f, dY: %f\n",
        gin->button, gin->state, gin->pX, gin->pY, gin->dX, gin->dY );

    return TCL_OK;
}

//--------------------------------------------------------------------------
// ProcessKey()
//
// Process keyboard events other than locate input.
//--------------------------------------------------------------------------

static void
ProcessKey( PLStream *pls )
{
    TkDev        *dev = (TkDev *) pls->dev;
    PLGraphicsIn *gin = &( dev->gin );

    dbug_enter( "ProcessKey" );

// Call user keypress event handler.  Since this is called first, the user
// can disable all internal event handling by setting key.keysym to 0.
//
    if ( pls->KeyEH != NULL )
        ( *pls->KeyEH )( gin, pls->KeyEH_data, &dev->exit_eventloop );

// Handle internal events

    switch ( gin->keysym )
    {
    case PLK_Return:
    case PLK_Linefeed:
    case PLK_Next:
        // Advance to next page (i.e. terminate event loop) on a <eol>
        // Check for both <CR> and <LF> for portability, also a <Page Down>
        dev->exit_eventloop = TRUE;
        break;

    case 'Q':
        // Terminate on a 'Q' (not 'q', since it's too easy to hit by mistake)
        tcl_cmd( pls, "abort" );
        break;

    case 'L':
        // Begin locate mode
        dev->locate_mode = LOCATE_INVOKED_VIA_DRIVER;
        server_cmd( pls, "$plwidget configure -xhairs on", 1 );
        break;
    }
}

//--------------------------------------------------------------------------
// ProcessButton()
//
// Process ButtonPress events other than locate input.
// On:
//   Button1: nothing (except when in locate mode, see ButtonLocate)
//   Button2: nothing
//   Button3: set page advance flag
//--------------------------------------------------------------------------

static void
ProcessButton( PLStream *pls )
{
    TkDev        *dev = (TkDev *) pls->dev;
    PLGraphicsIn *gin = &( dev->gin );

    dbug_enter( "ButtonEH" );

// Call user event handler.  Since this is called first, the user can
// disable all PLplot internal event handling by setting gin->button to 0.
//
    if ( pls->ButtonEH != NULL )
        ( *pls->ButtonEH )( gin, pls->ButtonEH_data, &dev->exit_eventloop );

// Handle internal events

    switch ( gin->button )
    {
    case Button3:
        dev->exit_eventloop = TRUE;
        break;
    }
}

//--------------------------------------------------------------------------
// LocateKey()
//
// Front-end to locate handler for KeyPress events.
// Only provides for:
//
//  <Escape>		Ends locate mode
//--------------------------------------------------------------------------

static void
LocateKey( PLStream *pls )
{
    TkDev        *dev = (TkDev *) pls->dev;
    PLGraphicsIn *gin = &( dev->gin );

// End locate mode on <Escape>

    if ( gin->keysym == PLK_Escape )
    {
        dev->locate_mode = 0;
        server_cmd( pls, "$plwidget configure -xhairs off", 1 );
        plGinInit( gin );
    }
    else
    {
        Locate( pls );
    }
}

//--------------------------------------------------------------------------
// LocateButton()
//
// Front-end to locate handler for ButtonPress events.
// Only passes control to Locate() for Button1 presses.
//--------------------------------------------------------------------------

static void
LocateButton( PLStream *pls )
{
    TkDev        *dev = (TkDev *) pls->dev;
    PLGraphicsIn *gin = &( dev->gin );

    switch ( gin->button )
    {
    case Button1:
        Locate( pls );
        break;
    }
}

//--------------------------------------------------------------------------
// Locate()
//
// Handles locate mode events.
//
// In locate mode: move cursor to desired location and select by pressing a
// key or by clicking on the mouse (if available).  Typically the world
// coordinates of the selected point are reported.
//
// There are two ways to enter Locate mode -- via the API, or via a driver
// command.  The API entry point is the call plGetCursor(), which initiates
// locate mode and does not return until input has been obtained.  The
// driver entry point is by entering a 'L' while the driver is waiting for
// events.
//
// Locate mode input is reported in one of three ways:
// 1. Through a returned PLGraphicsIn structure, when user has specified a
//    locate handler via (*pls->LocateEH).
// 2. Through a returned PLGraphicsIn structure, when locate mode is invoked
//    by a plGetCursor() call.
// 3. Through writes to stdout, when locate mode is invoked by a driver
//    command and the user has not supplied a locate handler.
//
// Hitting <Escape> will at all times end locate mode.  Other keys will
// typically be interpreted as locator input.  Selecting a point out of
// bounds will end locate mode unless the user overrides with a supplied
// Locate handler.
//--------------------------------------------------------------------------

static void
Locate( PLStream *pls )
{
    TkDev        *dev = (TkDev *) pls->dev;
    PLGraphicsIn *gin = &( dev->gin );

// Call user locate mode handler if provided

    if ( pls->LocateEH != NULL )
        ( *pls->LocateEH )( gin, pls->LocateEH_data, &dev->locate_mode );

// Use default procedure

    else
    {
        // Try to locate cursor

        if ( plTranslateCursor( gin ) )
        {
            // If invoked by the API, we're done
            // Otherwise send report to stdout

            if ( dev->locate_mode == LOCATE_INVOKED_VIA_DRIVER )
            {
                pltext();
                if ( gin->keysym < 0xFF && isprint( gin->keysym ) )
                    printf( "%f %f %c\n", gin->wX, gin->wY, gin->keysym );
                else
                    printf( "%f %f 0x%02x\n", gin->wX, gin->wY, gin->keysym );

                plgra();
            }
        }
        else
        {
            // Selected point is out of bounds, so end locate mode

            dev->locate_mode = 0;
            server_cmd( pls, "$plwidget configure -xhairs off", 1 );
        }
    }
}

//--------------------------------------------------------------------------
//
// pltk_toplevel --
//
//	Create top level window without mapping it.
//
// Results:
//	Returns 1 on error.
//
// Side effects:
//	Returns window ID as *w.
//
//--------------------------------------------------------------------------

static int
pltk_toplevel( Tk_Window *PL_UNUSED( w ), Tcl_Interp *interp )
{
    static char wcmd[] = "wm withdraw .";

// Create the main window without mapping it

    if ( Tk_Init( interp ) )
    {
        fprintf( stderr, "tk_init:%s\n", Tcl_GetStringResult( interp ) );
        return 1;
    }

    Tcl_VarEval( interp, wcmd, (char *) NULL );

    return 0;
}

//--------------------------------------------------------------------------
// tk_wait()
//
// Waits for the specified expression to evaluate to true before
// proceeding.  While we are waiting to proceed, all events (for this
// or other interpreters) are handled.
//
// Use a static string buffer to hold the command, to ensure it's in
// writable memory (grrr...).
//--------------------------------------------------------------------------

static void
tk_wait( PLStream *pls, const char *cmd )
{
    TkDev *dev   = (TkDev *) pls->dev;
    int   result = 0;

    dbug_enter( "tk_wait" );

    copybuf( pls, cmd );
    for (;; )
    {
        if ( Tcl_ExprBoolean( dev->interp, dev->cmdbuf, &result ) )
        {
            fprintf( stderr, "tk_wait command \"%s\" failed:\n\t %s\n",
                cmd, Tcl_GetStringResult( dev->interp ) );
            break;
        }
        if ( result )
            break;

        Tk_DoOneEvent( 0 );
    }
}

//--------------------------------------------------------------------------
// server_cmd
//
// Sends specified command to server, aborting on an error.
// If nowait is set, the command is issued in the background.
//
// If commands MUST proceed in a certain order (e.g. initialization), it
// is safest to NOT run them in the background.
//
// In order to protect args that have embedded spaces in them, I enclose
// the entire command in a [list ...], but for TK sends ONLY.  If done with
// Tcl-DP RPC, the sent command is no longer recognized.  Evidently an
// extra scan of the line is done with TK sends for some reason.
//--------------------------------------------------------------------------

static void
server_cmd( PLStream *pls, const char *cmd, int nowait )
{
    TkDev       *dev          = (TkDev *) pls->dev;
    static char dpsend_cmd0[] = "dp_RPC $server ";
    static char dpsend_cmd1[] = "dp_RDO $server ";
    static char tksend_cmd0[] = "send $server ";
    static char tksend_cmd1[] = "send $server after 1 ";
    int         result;

    dbug_enter( "server_cmd" );
    pldebug( "server_cmd", "Sending command: %s\n", cmd );

    if ( pls->dp )
    {
        if ( nowait )
            result = Tcl_VarEval( dev->interp, dpsend_cmd1, cmd,
                (char **) NULL );
        else
            result = Tcl_VarEval( dev->interp, dpsend_cmd0, cmd,
                (char **) NULL );
    }
    else
    {
        if ( nowait )
            result = Tcl_VarEval( dev->interp, tksend_cmd1, "[list ",
                cmd, "]", (char **) NULL );
        else
            result = Tcl_VarEval( dev->interp, tksend_cmd0, "[list ",
                cmd, "]", (char **) NULL );
    }

    if ( result != TCL_OK )
    {
        fprintf( stderr, "Server command \"%s\" failed:\n\t %s\n",
            cmd, Tcl_GetStringResult( dev->interp ) );
        abort_session( pls, "" );
    }
}

//--------------------------------------------------------------------------
// tcl_cmd
//
// Evals the specified command, aborting on an error.
//--------------------------------------------------------------------------

static void
tcl_cmd( PLStream *pls, const char *cmd )
{
    TkDev *dev = (TkDev *) pls->dev;

    dbug_enter( "tcl_cmd" );

    pldebug( "tcl_cmd", "Evaluating command: %s\n", cmd );
    if ( Tcl_VarEval( dev->interp, cmd, (char **) NULL ) != TCL_OK )
    {
        fprintf( stderr, "TCL command \"%s\" failed:\n\t %s\n",
            cmd, Tcl_GetStringResult( dev->interp ) );
        abort_session( pls, "" );
    }
}

//--------------------------------------------------------------------------
// copybuf
//
// Puts command in a static string buffer, to ensure it's in writable
// memory (grrr...).
//--------------------------------------------------------------------------

static void
copybuf( PLStream *pls, const char *cmd )
{
    TkDev *dev = (TkDev *) pls->dev;

    if ( dev->cmdbuf == NULL )
    {
        dev->cmdbuf_len = 100;
        dev->cmdbuf     = (char *) malloc( dev->cmdbuf_len );
    }

    if ( strlen( cmd ) >= dev->cmdbuf_len )
    {
        free( (void *) dev->cmdbuf );
        dev->cmdbuf_len = strlen( cmd ) + 20;
        dev->cmdbuf     = (char *) malloc( dev->cmdbuf_len );
    }

    strcpy( dev->cmdbuf, cmd );
}

//--------------------------------------------------------------------------
#else
int
pldummy_tk()
{
    return 0;
}

#endif                          // PLD_tk