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tkCanvLine.c

/* 
 * tkCanvLine.c --
 *
 *    This file implements line items for canvas widgets.
 *
 * Copyright (c) 1991-1994 The Regents of the University of California.
 * Copyright (c) 1994-1995 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tkCanvLine.c,v 1.2 1998/09/14 18:23:05 stanton Exp $
 */

#include <stdio.h>
#include "tkInt.h"
#include "tkPort.h"

/*
 * The structure below defines the record for each line item.
 */

typedef struct LineItem  {
    Tk_Item header;           /* Generic stuff that's the same for all
                         * types.  MUST BE FIRST IN STRUCTURE. */
    Tk_Canvas canvas;         /* Canvas containing item.  Needed for
                         * parsing arrow shapes. */
    int numPoints;            /* Number of points in line (always >= 2). */
    double *coordPtr;         /* Pointer to malloc-ed array containing
                         * x- and y-coords of all points in line.
                         * X-coords are even-valued indices, y-coords
                         * are corresponding odd-valued indices. If
                         * the line has arrowheads then the first
                         * and last points have been adjusted to refer
                         * to the necks of the arrowheads rather than
                         * their tips.  The actual endpoints are
                         * stored in the *firstArrowPtr and
                         * *lastArrowPtr, if they exist. */
    int width;                /* Width of line. */
    XColor *fg;               /* Foreground color for line. */
    Pixmap fillStipple;       /* Stipple bitmap for filling line. */
    int capStyle;       /* Cap style for line. */
    int joinStyle;            /* Join style for line. */
    GC gc;              /* Graphics context for filling line. */
    GC arrowGC;               /* Graphics context for drawing arrowheads. */
    Tk_Uid arrow;       /* Indicates whether or not to draw arrowheads:
                         * "none", "first", "last", or "both". */
    float arrowShapeA;        /* Distance from tip of arrowhead to center. */
    float arrowShapeB;        /* Distance from tip of arrowhead to trailing
                         * point, measured along shaft. */
    float arrowShapeC;        /* Distance of trailing points from outside
                         * edge of shaft. */
    double *firstArrowPtr;    /* Points to array of PTS_IN_ARROW points
                         * describing polygon for arrowhead at first
                         * point in line.  First point of arrowhead
                         * is tip.  Malloc'ed.  NULL means no arrowhead
                         * at first point. */
    double *lastArrowPtr;     /* Points to polygon for arrowhead at last
                         * point in line (PTS_IN_ARROW points, first
                         * of which is tip).  Malloc'ed.  NULL means
                         * no arrowhead at last point. */
    int smooth;               /* Non-zero means draw line smoothed (i.e.
                         * with Bezier splines). */
    int splineSteps;          /* Number of steps in each spline segment. */
} LineItem;

/*
 * Number of points in an arrowHead:
 */

#define PTS_IN_ARROW 6

/*
 * Prototypes for procedures defined in this file:
 */

static int        ArrowheadPostscript _ANSI_ARGS_((Tcl_Interp *interp,
                      Tk_Canvas canvas, LineItem *linePtr,
                      double *arrowPtr));
static void       ComputeLineBbox _ANSI_ARGS_((Tk_Canvas canvas,
                      LineItem *linePtr));
static int        ConfigureLine _ANSI_ARGS_((Tcl_Interp *interp,
                      Tk_Canvas canvas, Tk_Item *itemPtr, int argc,
                      char **argv, int flags));
static int        ConfigureArrows _ANSI_ARGS_((Tk_Canvas canvas,
                      LineItem *linePtr));
static int        CreateLine _ANSI_ARGS_((Tcl_Interp *interp,
                      Tk_Canvas canvas, struct Tk_Item *itemPtr,
                      int argc, char **argv));
static void       DeleteLine _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, Display *display));
static void       DisplayLine _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, Display *display, Drawable dst,
                      int x, int y, int width, int height));
static int        LineCoords _ANSI_ARGS_((Tcl_Interp *interp,
                      Tk_Canvas canvas, Tk_Item *itemPtr,
                      int argc, char **argv));
static int        LineToArea _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, double *rectPtr));
static double           LineToPoint _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, double *coordPtr));
static int        LineToPostscript _ANSI_ARGS_((Tcl_Interp *interp,
                      Tk_Canvas canvas, Tk_Item *itemPtr, int prepass));
static int        ParseArrowShape _ANSI_ARGS_((ClientData clientData,
                      Tcl_Interp *interp, Tk_Window tkwin, char *value,
                      char *recordPtr, int offset));
static char *           PrintArrowShape _ANSI_ARGS_((ClientData clientData,
                      Tk_Window tkwin, char *recordPtr, int offset,
                      Tcl_FreeProc **freeProcPtr));
static void       ScaleLine _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, double originX, double originY,
                      double scaleX, double scaleY));
static void       TranslateLine _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, double deltaX, double deltaY));

/*
 * Information used for parsing configuration specs.  If you change any
 * of the default strings, be sure to change the corresponding default
 * values in CreateLine.
 */

static Tk_CustomOption arrowShapeOption = {ParseArrowShape,
      PrintArrowShape, (ClientData) NULL};
static Tk_CustomOption tagsOption = {Tk_CanvasTagsParseProc,
    Tk_CanvasTagsPrintProc, (ClientData) NULL
};

static Tk_ConfigSpec configSpecs[] = {
    {TK_CONFIG_UID, "-arrow", (char *) NULL, (char *) NULL,
      "none", Tk_Offset(LineItem, arrow), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_CUSTOM, "-arrowshape", (char *) NULL, (char *) NULL,
      "8 10 3", Tk_Offset(LineItem, arrowShapeA),
      TK_CONFIG_DONT_SET_DEFAULT, &arrowShapeOption},
    {TK_CONFIG_CAP_STYLE, "-capstyle", (char *) NULL, (char *) NULL,
      "butt", Tk_Offset(LineItem, capStyle), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_COLOR, "-fill", (char *) NULL, (char *) NULL,
      "black", Tk_Offset(LineItem, fg), TK_CONFIG_NULL_OK},
    {TK_CONFIG_JOIN_STYLE, "-joinstyle", (char *) NULL, (char *) NULL,
      "round", Tk_Offset(LineItem, joinStyle), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_BOOLEAN, "-smooth", (char *) NULL, (char *) NULL,
      "0", Tk_Offset(LineItem, smooth), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_INT, "-splinesteps", (char *) NULL, (char *) NULL,
      "12", Tk_Offset(LineItem, splineSteps), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_BITMAP, "-stipple", (char *) NULL, (char *) NULL,
      (char *) NULL, Tk_Offset(LineItem, fillStipple), TK_CONFIG_NULL_OK},
    {TK_CONFIG_CUSTOM, "-tags", (char *) NULL, (char *) NULL,
      (char *) NULL, 0, TK_CONFIG_NULL_OK, &tagsOption},
    {TK_CONFIG_PIXELS, "-width", (char *) NULL, (char *) NULL,
      "1", Tk_Offset(LineItem, width), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_END, (char *) NULL, (char *) NULL, (char *) NULL,
      (char *) NULL, 0, 0}
};

/*
 * The structures below defines the line item type by means
 * of procedures that can be invoked by generic item code.
 */

Tk_ItemType tkLineType = {
    "line",                   /* name */
    sizeof(LineItem),               /* itemSize */
    CreateLine,                     /* createProc */
    configSpecs,              /* configSpecs */
    ConfigureLine,                  /* configureProc */
    LineCoords,                     /* coordProc */
    DeleteLine,                     /* deleteProc */
    DisplayLine,              /* displayProc */
    0,                              /* alwaysRedraw */
    LineToPoint,              /* pointProc */
    LineToArea,                     /* areaProc */
    LineToPostscript,               /* postscriptProc */
    ScaleLine,                      /* scaleProc */
    TranslateLine,                  /* translateProc */
    (Tk_ItemIndexProc *) NULL,            /* indexProc */
    (Tk_ItemCursorProc *) NULL,           /* icursorProc */
    (Tk_ItemSelectionProc *) NULL,  /* selectionProc */
    (Tk_ItemInsertProc *) NULL,           /* insertProc */
    (Tk_ItemDCharsProc *) NULL,           /* dTextProc */
    (Tk_ItemType *) NULL            /* nextPtr */
};

/*
 * The Tk_Uid's below refer to uids for the various arrow types:
 */

static Tk_Uid noneUid = NULL;
static Tk_Uid firstUid = NULL;
static Tk_Uid lastUid = NULL;
static Tk_Uid bothUid = NULL;

/*
 * The definition below determines how large are static arrays
 * used to hold spline points (splines larger than this have to
 * have their arrays malloc-ed).
 */

#define MAX_STATIC_POINTS 200

/*
 *--------------------------------------------------------------
 *
 * CreateLine --
 *
 *    This procedure is invoked to create a new line item in
 *    a canvas.
 *
 * Results:
 *    A standard Tcl return value.  If an error occurred in
 *    creating the item, then an error message is left in
 *    interp->result;  in this case itemPtr is left uninitialized,
 *    so it can be safely freed by the caller.
 *
 * Side effects:
 *    A new line item is created.
 *
 *--------------------------------------------------------------
 */

static int
CreateLine(interp, canvas, itemPtr, argc, argv)
    Tcl_Interp *interp;             /* Interpreter for error reporting. */
    Tk_Canvas canvas;               /* Canvas to hold new item. */
    Tk_Item *itemPtr;               /* Record to hold new item;  header
                               * has been initialized by caller. */
    int argc;                       /* Number of arguments in argv. */
    char **argv;              /* Arguments describing line. */
{
    LineItem *linePtr = (LineItem *) itemPtr;
    int i;

    if (argc < 4) {
      Tcl_AppendResult(interp, "wrong # args: should be \"",
            Tk_PathName(Tk_CanvasTkwin(canvas)), " create ",
            itemPtr->typePtr->name, " x1 y1 x2 y2 ?x3 y3 ...? ?options?\"",
            (char *) NULL);
      return TCL_ERROR;
    }

    /*
     * Carry out initialization that is needed to set defaults and to
     * allow proper cleanup after errors during the the remainder of
     * this procedure.
     */

    linePtr->canvas = canvas;
    linePtr->numPoints = 0;
    linePtr->coordPtr = NULL;
    linePtr->width = 1;
    linePtr->fg = None;
    linePtr->fillStipple = None;
    linePtr->capStyle = CapButt;
    linePtr->joinStyle = JoinRound;
    linePtr->gc = None;
    linePtr->arrowGC = None;
    if (noneUid == NULL) {
      noneUid = Tk_GetUid("none");
      firstUid = Tk_GetUid("first");
      lastUid = Tk_GetUid("last");
      bothUid = Tk_GetUid("both");
    }
    linePtr->arrow = noneUid;
    linePtr->arrowShapeA = (float)8.0;
    linePtr->arrowShapeB = (float)10.0;
    linePtr->arrowShapeC = (float)3.0;
    linePtr->firstArrowPtr = NULL;
    linePtr->lastArrowPtr = NULL;
    linePtr->smooth = 0;
    linePtr->splineSteps = 12;

    /*
     * Count the number of points and then parse them into a point
     * array.  Leading arguments are assumed to be points if they
     * start with a digit or a minus sign followed by a digit.
     */

    for (i = 4; i < (argc-1); i+=2) {
      if ((!isdigit(UCHAR(argv[i][0]))) &&
            ((argv[i][0] != '-')
            || ((argv[i][1] != '.') && !isdigit(UCHAR(argv[i][1]))))) {
          break;
      }
    }
    if (LineCoords(interp, canvas, itemPtr, i, argv) != TCL_OK) {
      goto error;
    }
    if (ConfigureLine(interp, canvas, itemPtr, argc-i, argv+i, 0) == TCL_OK) {
      return TCL_OK;
    }

    error:
    DeleteLine(canvas, itemPtr, Tk_Display(Tk_CanvasTkwin(canvas)));
    return TCL_ERROR;
}

/*
 *--------------------------------------------------------------
 *
 * LineCoords --
 *
 *    This procedure is invoked to process the "coords" widget
 *    command on lines.  See the user documentation for details
 *    on what it does.
 *
 * Results:
 *    Returns TCL_OK or TCL_ERROR, and sets interp->result.
 *
 * Side effects:
 *    The coordinates for the given item may be changed.
 *
 *--------------------------------------------------------------
 */

static int
LineCoords(interp, canvas, itemPtr, argc, argv)
    Tcl_Interp *interp;             /* Used for error reporting. */
    Tk_Canvas canvas;               /* Canvas containing item. */
    Tk_Item *itemPtr;               /* Item whose coordinates are to be
                               * read or modified. */
    int argc;                       /* Number of coordinates supplied in
                               * argv. */
    char **argv;              /* Array of coordinates: x1, y1,
                               * x2, y2, ... */
{
    LineItem *linePtr = (LineItem *) itemPtr;
    char buffer[TCL_DOUBLE_SPACE];
    int i, numPoints;

    if (argc == 0) {
      double *coordPtr;
      int numCoords;

      numCoords = 2*linePtr->numPoints;
      if (linePtr->firstArrowPtr != NULL) {
          coordPtr = linePtr->firstArrowPtr;
      } else {
          coordPtr = linePtr->coordPtr;
      }
      for (i = 0; i < numCoords; i++, coordPtr++) {
          if (i == 2) {
            coordPtr = linePtr->coordPtr+2;
          }
          if ((linePtr->lastArrowPtr != NULL) && (i == (numCoords-2))) {
            coordPtr = linePtr->lastArrowPtr;
          }
          Tcl_PrintDouble(interp, *coordPtr, buffer);
          Tcl_AppendElement(interp, buffer);
      }
    } else if (argc < 4) {
      Tcl_AppendResult(interp,
            "too few coordinates for line: must have at least 4",
            (char *) NULL);
      return TCL_ERROR;
    } else if (argc & 1) {
      Tcl_AppendResult(interp,
            "odd number of coordinates specified for line",
            (char *) NULL);
      return TCL_ERROR;
    } else {
      numPoints = argc/2;
      if (linePtr->numPoints != numPoints) {
          if (linePtr->coordPtr != NULL) {
            ckfree((char *) linePtr->coordPtr);
          }
          linePtr->coordPtr = (double *) ckalloc((unsigned)
                (sizeof(double) * argc));
          linePtr->numPoints = numPoints;
      }
      for (i = argc-1; i >= 0; i--) {
          if (Tk_CanvasGetCoord(interp, canvas, argv[i],
                &linePtr->coordPtr[i]) != TCL_OK) {
            return TCL_ERROR;
          }
      }

      /*
       * Update arrowheads by throwing away any existing arrow-head
       * information and calling ConfigureArrows to recompute it.
       */

      if (linePtr->firstArrowPtr != NULL) {
          ckfree((char *) linePtr->firstArrowPtr);
          linePtr->firstArrowPtr = NULL;
      }
      if (linePtr->lastArrowPtr != NULL) {
          ckfree((char *) linePtr->lastArrowPtr);
          linePtr->lastArrowPtr = NULL;
      }
      if (linePtr->arrow != noneUid) {
          ConfigureArrows(canvas, linePtr);
      }
      ComputeLineBbox(canvas, linePtr);
    }
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * ConfigureLine --
 *
 *    This procedure is invoked to configure various aspects
 *    of a line item such as its background color.
 *
 * Results:
 *    A standard Tcl result code.  If an error occurs, then
 *    an error message is left in interp->result.
 *
 * Side effects:
 *    Configuration information, such as colors and stipple
 *    patterns, may be set for itemPtr.
 *
 *--------------------------------------------------------------
 */

static int
ConfigureLine(interp, canvas, itemPtr, argc, argv, flags)
    Tcl_Interp *interp;       /* Used for error reporting. */
    Tk_Canvas canvas;         /* Canvas containing itemPtr. */
    Tk_Item *itemPtr;         /* Line item to reconfigure. */
    int argc;                 /* Number of elements in argv.  */
    char **argv;        /* Arguments describing things to configure. */
    int flags;                /* Flags to pass to Tk_ConfigureWidget. */
{
    LineItem *linePtr = (LineItem *) itemPtr;
    XGCValues gcValues;
    GC newGC, arrowGC;
    unsigned long mask;
    Tk_Window tkwin;

    tkwin = Tk_CanvasTkwin(canvas);
    if (Tk_ConfigureWidget(interp, tkwin, configSpecs, argc, argv,
          (char *) linePtr, flags) != TCL_OK) {
      return TCL_ERROR;
    }

    /*
     * A few of the options require additional processing, such as
     * graphics contexts.
     */

    if (linePtr->fg == NULL) {
      newGC = arrowGC = None;
    } else {
      gcValues.foreground = linePtr->fg->pixel;
      gcValues.join_style = linePtr->joinStyle;
      if (linePtr->width < 0) {
          linePtr->width = 1;
      }
      gcValues.line_width = linePtr->width;
      mask = GCForeground|GCJoinStyle|GCLineWidth;
      if (linePtr->fillStipple != None) {
          gcValues.stipple = linePtr->fillStipple;
          gcValues.fill_style = FillStippled;
          mask |= GCStipple|GCFillStyle;
      }
      if (linePtr->arrow == noneUid) {
          gcValues.cap_style = linePtr->capStyle;
          mask |= GCCapStyle;
      }
      newGC = Tk_GetGC(tkwin, mask, &gcValues);
      gcValues.line_width = 0;
      arrowGC = Tk_GetGC(tkwin, mask, &gcValues);
    }
    if (linePtr->gc != None) {
      Tk_FreeGC(Tk_Display(tkwin), linePtr->gc);
    }
    if (linePtr->arrowGC != None) {
      Tk_FreeGC(Tk_Display(tkwin), linePtr->arrowGC);
    }
    linePtr->gc = newGC;
    linePtr->arrowGC = arrowGC;

    /*
     * Keep spline parameters within reasonable limits.
     */

    if (linePtr->splineSteps < 1) {
      linePtr->splineSteps = 1;
    } else if (linePtr->splineSteps > 100) {
      linePtr->splineSteps = 100;
    }

    /*
     * Setup arrowheads, if needed.  If arrowheads are turned off,
     * restore the line's endpoints (they were shortened when the
     * arrowheads were added).
     */

    if ((linePtr->firstArrowPtr != NULL) && (linePtr->arrow != firstUid)
          && (linePtr->arrow != bothUid)) {
      linePtr->coordPtr[0] = linePtr->firstArrowPtr[0];
      linePtr->coordPtr[1] = linePtr->firstArrowPtr[1];
      ckfree((char *) linePtr->firstArrowPtr);
      linePtr->firstArrowPtr = NULL;
    }
    if ((linePtr->lastArrowPtr != NULL) && (linePtr->arrow != lastUid)
          && (linePtr->arrow != bothUid)) {
      int i;

      i = 2*(linePtr->numPoints-1);
      linePtr->coordPtr[i] = linePtr->lastArrowPtr[0];
      linePtr->coordPtr[i+1] = linePtr->lastArrowPtr[1];
      ckfree((char *) linePtr->lastArrowPtr);
      linePtr->lastArrowPtr = NULL;
    }
    if (linePtr->arrow != noneUid) {
      if ((linePtr->arrow != firstUid) && (linePtr->arrow != lastUid)
            && (linePtr->arrow != bothUid)) {
          Tcl_AppendResult(interp, "bad arrow spec \"",
                linePtr->arrow, "\": must be none, first, last, or both",
                (char *) NULL);
          linePtr->arrow = noneUid;
          return TCL_ERROR;
      }
      ConfigureArrows(canvas, linePtr);
    }

    /*
     * Recompute bounding box for line.
     */

    ComputeLineBbox(canvas, linePtr);

    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * DeleteLine --
 *
 *    This procedure is called to clean up the data structure
 *    associated with a line item.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    Resources associated with itemPtr are released.
 *
 *--------------------------------------------------------------
 */

static void
DeleteLine(canvas, itemPtr, display)
    Tk_Canvas canvas;               /* Info about overall canvas widget. */
    Tk_Item *itemPtr;               /* Item that is being deleted. */
    Display *display;               /* Display containing window for
                               * canvas. */
{
    LineItem *linePtr = (LineItem *) itemPtr;

    if (linePtr->coordPtr != NULL) {
      ckfree((char *) linePtr->coordPtr);
    }
    if (linePtr->fg != NULL) {
      Tk_FreeColor(linePtr->fg);
    }
    if (linePtr->fillStipple != None) {
      Tk_FreeBitmap(display, linePtr->fillStipple);
    }
    if (linePtr->gc != None) {
      Tk_FreeGC(display, linePtr->gc);
    }
    if (linePtr->arrowGC != None) {
      Tk_FreeGC(display, linePtr->arrowGC);
    }
    if (linePtr->firstArrowPtr != NULL) {
      ckfree((char *) linePtr->firstArrowPtr);
    }
    if (linePtr->lastArrowPtr != NULL) {
      ckfree((char *) linePtr->lastArrowPtr);
    }
}

/*
 *--------------------------------------------------------------
 *
 * ComputeLineBbox --
 *
 *    This procedure is invoked to compute the bounding box of
 *    all the pixels that may be drawn as part of a line.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    The fields x1, y1, x2, and y2 are updated in the header
 *    for itemPtr.
 *
 *--------------------------------------------------------------
 */

static void
ComputeLineBbox(canvas, linePtr)
    Tk_Canvas canvas;               /* Canvas that contains item. */
    LineItem *linePtr;              /* Item whose bbos is to be
                               * recomputed. */
{
    double *coordPtr;
    int i, width;

    coordPtr = linePtr->coordPtr;
    linePtr->header.x1 = linePtr->header.x2 = (int) *coordPtr;
    linePtr->header.y1 = linePtr->header.y2 = (int) coordPtr[1];

    /*
     * Compute the bounding box of all the points in the line,
     * then expand in all directions by the line's width to take
     * care of butting or rounded corners and projecting or
     * rounded caps.  This expansion is an overestimate (worst-case
     * is square root of two over two) but it's simple.  Don't do
     * anything special for curves.  This causes an additional
     * overestimate in the bounding box, but is faster.
     */

    for (i = 1, coordPtr = linePtr->coordPtr+2; i < linePtr->numPoints;
          i++, coordPtr += 2) {
      TkIncludePoint((Tk_Item *) linePtr, coordPtr);
    }
    width = linePtr->width;
    if (width < 1) {
      width = 1;
    }
    linePtr->header.x1 -= width;
    linePtr->header.x2 += width;
    linePtr->header.y1 -= width;
    linePtr->header.y2 += width;

    /*
     * For mitered lines, make a second pass through all the points.
     * Compute the locations of the two miter vertex points and add
     * those into the bounding box.
     */

    if (linePtr->joinStyle == JoinMiter) {
      for (i = linePtr->numPoints, coordPtr = linePtr->coordPtr; i >= 3;
            i--, coordPtr += 2) {
          double miter[4];
          int j;
    
          if (TkGetMiterPoints(coordPtr, coordPtr+2, coordPtr+4,
                (double) width, miter, miter+2)) {
            for (j = 0; j < 4; j += 2) {
                TkIncludePoint((Tk_Item *) linePtr, miter+j);
            }
          }
      }
    }

    /*
     * Add in the sizes of arrowheads, if any.
     */

    if (linePtr->arrow != noneUid) {
      if (linePtr->arrow != lastUid) {
          for (i = 0, coordPtr = linePtr->firstArrowPtr; i < PTS_IN_ARROW;
                i++, coordPtr += 2) {
            TkIncludePoint((Tk_Item *) linePtr, coordPtr);
          }
      }
      if (linePtr->arrow != firstUid) {
          for (i = 0, coordPtr = linePtr->lastArrowPtr; i < PTS_IN_ARROW;
                i++, coordPtr += 2) {
            TkIncludePoint((Tk_Item *) linePtr, coordPtr);
          }
      }
    }

    /*
     * Add one more pixel of fudge factor just to be safe (e.g.
     * X may round differently than we do).
     */

    linePtr->header.x1 -= 1;
    linePtr->header.x2 += 1;
    linePtr->header.y1 -= 1;
    linePtr->header.y2 += 1;
}

/*
 *--------------------------------------------------------------
 *
 * DisplayLine --
 *
 *    This procedure is invoked to draw a line item in a given
 *    drawable.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    ItemPtr is drawn in drawable using the transformation
 *    information in canvas.
 *
 *--------------------------------------------------------------
 */

static void
DisplayLine(canvas, itemPtr, display, drawable, x, y, width, height)
    Tk_Canvas canvas;               /* Canvas that contains item. */
    Tk_Item *itemPtr;               /* Item to be displayed. */
    Display *display;               /* Display on which to draw item. */
    Drawable drawable;              /* Pixmap or window in which to draw
                               * item. */
    int x, y, width, height;        /* Describes region of canvas that
                               * must be redisplayed (not used). */
{
    LineItem *linePtr = (LineItem *) itemPtr;
    XPoint staticPoints[MAX_STATIC_POINTS];
    XPoint *pointPtr;
    XPoint *pPtr;
    double *coordPtr;
    int i, numPoints;

    if (linePtr->gc == None) {
      return;
    }

    /*
     * Build up an array of points in screen coordinates.  Use a
     * static array unless the line has an enormous number of points;
     * in this case, dynamically allocate an array.  For smoothed lines,
     * generate the curve points on each redisplay.
     */

    if ((linePtr->smooth) && (linePtr->numPoints > 2)) {
      numPoints = 1 + linePtr->numPoints*linePtr->splineSteps;
    } else {
      numPoints = linePtr->numPoints;
    }

    if (numPoints <= MAX_STATIC_POINTS) {
      pointPtr = staticPoints;
    } else {
      pointPtr = (XPoint *) ckalloc((unsigned) (numPoints * sizeof(XPoint)));
    }

    if ((linePtr->smooth) && (linePtr->numPoints > 2)) {
      numPoints = TkMakeBezierCurve(canvas, linePtr->coordPtr,
            linePtr->numPoints, linePtr->splineSteps, pointPtr,
            (double *) NULL);
    } else {
      for (i = 0, coordPtr = linePtr->coordPtr, pPtr = pointPtr;
            i < linePtr->numPoints;  i += 1, coordPtr += 2, pPtr++) {
          Tk_CanvasDrawableCoords(canvas, coordPtr[0], coordPtr[1],
                &pPtr->x, &pPtr->y);
      }
    }

    /*
     * Display line, the free up line storage if it was dynamically
     * allocated.  If we're stippling, then modify the stipple offset
     * in the GC.  Be sure to reset the offset when done, since the
     * GC is supposed to be read-only.
     */

    if (linePtr->fillStipple != None) {
      Tk_CanvasSetStippleOrigin(canvas, linePtr->gc);
      Tk_CanvasSetStippleOrigin(canvas, linePtr->arrowGC);
    }
    XDrawLines(display, drawable, linePtr->gc, pointPtr, numPoints,
          CoordModeOrigin);
    if (pointPtr != staticPoints) {
      ckfree((char *) pointPtr);
    }

    /*
     * Display arrowheads, if they are wanted.
     */

    if (linePtr->firstArrowPtr != NULL) {
      TkFillPolygon(canvas, linePtr->firstArrowPtr, PTS_IN_ARROW,
            display, drawable, linePtr->gc, NULL);
    }
    if (linePtr->lastArrowPtr != NULL) {
      TkFillPolygon(canvas, linePtr->lastArrowPtr, PTS_IN_ARROW,
            display, drawable, linePtr->gc, NULL);
    }
    if (linePtr->fillStipple != None) {
      XSetTSOrigin(display, linePtr->gc, 0, 0);
      XSetTSOrigin(display, linePtr->arrowGC, 0, 0);
    }
}

/*
 *--------------------------------------------------------------
 *
 * LineToPoint --
 *
 *    Computes the distance from a given point to a given
 *    line, in canvas units.
 *
 * Results:
 *    The return value is 0 if the point whose x and y coordinates
 *    are pointPtr[0] and pointPtr[1] is inside the line.  If the
 *    point isn't inside the line then the return value is the
 *    distance from the point to the line.
 *
 * Side effects:
 *    None.
 *
 *--------------------------------------------------------------
 */

      /* ARGSUSED */
static double
LineToPoint(canvas, itemPtr, pointPtr)
    Tk_Canvas canvas;         /* Canvas containing item. */
    Tk_Item *itemPtr;         /* Item to check against point. */
    double *pointPtr;         /* Pointer to x and y coordinates. */
{
    LineItem *linePtr = (LineItem *) itemPtr;
    double *coordPtr, *linePoints;
    double staticSpace[2*MAX_STATIC_POINTS];
    double poly[10];
    double bestDist, dist;
    int numPoints, count;
    int changedMiterToBevel;  /* Non-zero means that a mitered corner
                         * had to be treated as beveled after all
                         * because the angle was < 11 degrees. */

    bestDist = 1.0e36;

    /*
     * Handle smoothed lines by generating an expanded set of points
     * against which to do the check.
     */

    if ((linePtr->smooth) && (linePtr->numPoints > 2)) {
      numPoints = 1 + linePtr->numPoints*linePtr->splineSteps;
      if (numPoints <= MAX_STATIC_POINTS) {
          linePoints = staticSpace;
      } else {
          linePoints = (double *) ckalloc((unsigned)
                (2*numPoints*sizeof(double)));
      }
      numPoints = TkMakeBezierCurve(canvas, linePtr->coordPtr,
            linePtr->numPoints, linePtr->splineSteps, (XPoint *) NULL,
            linePoints);
    } else {
      numPoints = linePtr->numPoints;
      linePoints = linePtr->coordPtr;
    }

    /*
     * The overall idea is to iterate through all of the edges of
     * the line, computing a polygon for each edge and testing the
     * point against that polygon.  In addition, there are additional
     * tests to deal with rounded joints and caps.
     */

    changedMiterToBevel = 0;
    for (count = numPoints, coordPtr = linePoints; count >= 2;
          count--, coordPtr += 2) {

      /*
       * If rounding is done around the first point then compute
       * the distance between the point and the point.
       */

      if (((linePtr->capStyle == CapRound) && (count == numPoints))
            || ((linePtr->joinStyle == JoinRound)
                  && (count != numPoints))) {
          dist = hypot(coordPtr[0] - pointPtr[0], coordPtr[1] - pointPtr[1])
                - linePtr->width/2.0;
          if (dist <= 0.0) {
            bestDist = 0.0;
            goto done;
          } else if (dist < bestDist) {
            bestDist = dist;
          }
      }

      /*
       * Compute the polygonal shape corresponding to this edge,
       * consisting of two points for the first point of the edge
       * and two points for the last point of the edge.
       */

      if (count == numPoints) {
          TkGetButtPoints(coordPtr+2, coordPtr, (double) linePtr->width,
                linePtr->capStyle == CapProjecting, poly, poly+2);
      } else if ((linePtr->joinStyle == JoinMiter) && !changedMiterToBevel) {
          poly[0] = poly[6];
          poly[1] = poly[7];
          poly[2] = poly[4];
          poly[3] = poly[5];
      } else {
          TkGetButtPoints(coordPtr+2, coordPtr, (double) linePtr->width, 0,
                poly, poly+2);

          /*
           * If this line uses beveled joints, then check the distance
           * to a polygon comprising the last two points of the previous
           * polygon and the first two from this polygon;  this checks
           * the wedges that fill the mitered joint.
           */

          if ((linePtr->joinStyle == JoinBevel) || changedMiterToBevel) {
            poly[8] = poly[0];
            poly[9] = poly[1];
            dist = TkPolygonToPoint(poly, 5, pointPtr);
            if (dist <= 0.0) {
                bestDist = 0.0;
                goto done;
            } else if (dist < bestDist) {
                bestDist = dist;
            }
            changedMiterToBevel = 0;
          }
      }
      if (count == 2) {
          TkGetButtPoints(coordPtr, coordPtr+2, (double) linePtr->width,
                linePtr->capStyle == CapProjecting, poly+4, poly+6);
      } else if (linePtr->joinStyle == JoinMiter) {
          if (TkGetMiterPoints(coordPtr, coordPtr+2, coordPtr+4,
                (double) linePtr->width, poly+4, poly+6) == 0) {
            changedMiterToBevel = 1;
            TkGetButtPoints(coordPtr, coordPtr+2, (double) linePtr->width,
                  0, poly+4, poly+6);
          }
      } else {
          TkGetButtPoints(coordPtr, coordPtr+2, (double) linePtr->width, 0,
                poly+4, poly+6);
      }
      poly[8] = poly[0];
      poly[9] = poly[1];
      dist = TkPolygonToPoint(poly, 5, pointPtr);
      if (dist <= 0.0) {
          bestDist = 0.0;
          goto done;
      } else if (dist < bestDist) {
          bestDist = dist;
      }
    }

    /*
     * If caps are rounded, check the distance to the cap around the
     * final end point of the line.
     */

    if (linePtr->capStyle == CapRound) {
      dist = hypot(coordPtr[0] - pointPtr[0], coordPtr[1] - pointPtr[1])
            - linePtr->width/2.0;
      if (dist <= 0.0) {
          bestDist = 0.0;
          goto done;
      } else if (dist < bestDist) {
          bestDist = dist;
      }
    }

    /*
     * If there are arrowheads, check the distance to the arrowheads.
     */

    if (linePtr->arrow != noneUid) {
      if (linePtr->arrow != lastUid) {
          dist = TkPolygonToPoint(linePtr->firstArrowPtr, PTS_IN_ARROW,
                pointPtr);
          if (dist <= 0.0) {
            bestDist = 0.0;
            goto done;
          } else if (dist < bestDist) {
            bestDist = dist;
          }
      }
      if (linePtr->arrow != firstUid) {
          dist = TkPolygonToPoint(linePtr->lastArrowPtr, PTS_IN_ARROW,
                pointPtr);
          if (dist <= 0.0) {
            bestDist = 0.0;
            goto done;
          } else if (dist < bestDist) {
            bestDist = dist;
          }
      }
    }

    done:
    if ((linePoints != staticSpace) && (linePoints != linePtr->coordPtr)) {
      ckfree((char *) linePoints);
    }
    return bestDist;
}

/*
 *--------------------------------------------------------------
 *
 * LineToArea --
 *
 *    This procedure is called to determine whether an item
 *    lies entirely inside, entirely outside, or overlapping
 *    a given rectangular area.
 *
 * Results:
 *    -1 is returned if the item is entirely outside the
 *    area, 0 if it overlaps, and 1 if it is entirely
 *    inside the given area.
 *
 * Side effects:
 *    None.
 *
 *--------------------------------------------------------------
 */

      /* ARGSUSED */
static int
LineToArea(canvas, itemPtr, rectPtr)
    Tk_Canvas canvas;         /* Canvas containing item. */
    Tk_Item *itemPtr;         /* Item to check against line. */
    double *rectPtr;
{
    LineItem *linePtr = (LineItem *) itemPtr;
    double staticSpace[2*MAX_STATIC_POINTS];
    double *linePoints;
    int numPoints, result;

    /*
     * Handle smoothed lines by generating an expanded set of points
     * against which to do the check.
     */

    if ((linePtr->smooth) && (linePtr->numPoints > 2)) {
      numPoints = 1 + linePtr->numPoints*linePtr->splineSteps;
      if (numPoints <= MAX_STATIC_POINTS) {
          linePoints = staticSpace;
      } else {
          linePoints = (double *) ckalloc((unsigned)
                (2*numPoints*sizeof(double)));
      }
      numPoints = TkMakeBezierCurve(canvas, linePtr->coordPtr,
            linePtr->numPoints, linePtr->splineSteps, (XPoint *) NULL,
            linePoints);
    } else {
      numPoints = linePtr->numPoints;
      linePoints = linePtr->coordPtr;
    }

    /*
     * Check the segments of the line.
     */

    result = TkThickPolyLineToArea(linePoints, numPoints, 
          (double) linePtr->width, linePtr->capStyle, linePtr->joinStyle,
          rectPtr);
    if (result == 0) {
      goto done;
    }

    /*
     * Check arrowheads, if any.
     */

    if (linePtr->arrow != noneUid) {
      if (linePtr->arrow != lastUid) {
          if (TkPolygonToArea(linePtr->firstArrowPtr, PTS_IN_ARROW,
                rectPtr) != result) {
            result = 0;
            goto done;
          }
      }
      if (linePtr->arrow != firstUid) {
          if (TkPolygonToArea(linePtr->lastArrowPtr, PTS_IN_ARROW,
                rectPtr) != result) {
            result = 0;
            goto done;
          }
      }
    }

    done:
    if ((linePoints != staticSpace) && (linePoints != linePtr->coordPtr)) {
      ckfree((char *) linePoints);
    }
    return result;
}

/*
 *--------------------------------------------------------------
 *
 * ScaleLine --
 *
 *    This procedure is invoked to rescale a line item.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    The line referred to by itemPtr is rescaled so that the
 *    following transformation is applied to all point
 *    coordinates:
 *          x' = originX + scaleX*(x-originX)
 *          y' = originY + scaleY*(y-originY)
 *
 *--------------------------------------------------------------
 */

static void
ScaleLine(canvas, itemPtr, originX, originY, scaleX, scaleY)
    Tk_Canvas canvas;               /* Canvas containing line. */
    Tk_Item *itemPtr;               /* Line to be scaled. */
    double originX, originY;        /* Origin about which to scale rect. */
    double scaleX;                  /* Amount to scale in X direction. */
    double scaleY;                  /* Amount to scale in Y direction. */
{
    LineItem *linePtr = (LineItem *) itemPtr;
    double *coordPtr;
    int i;

    /*
     * Delete any arrowheads before scaling all the points (so that
     * the end-points of the line get restored).
     */

    if (linePtr->firstArrowPtr != NULL) {
      linePtr->coordPtr[0] = linePtr->firstArrowPtr[0];
      linePtr->coordPtr[1] = linePtr->firstArrowPtr[1];
      ckfree((char *) linePtr->firstArrowPtr);
      linePtr->firstArrowPtr = NULL;
    }
    if (linePtr->lastArrowPtr != NULL) {
      int i;

      i = 2*(linePtr->numPoints-1);
      linePtr->coordPtr[i] = linePtr->lastArrowPtr[0];
      linePtr->coordPtr[i+1] = linePtr->lastArrowPtr[1];
      ckfree((char *) linePtr->lastArrowPtr);
      linePtr->lastArrowPtr = NULL;
    }
    for (i = 0, coordPtr = linePtr->coordPtr; i < linePtr->numPoints;
          i++, coordPtr += 2) {
      coordPtr[0] = originX + scaleX*(*coordPtr - originX);
      coordPtr[1] = originY + scaleY*(coordPtr[1] - originY);
    }
    if (linePtr->arrow != noneUid) {
      ConfigureArrows(canvas, linePtr);
    }
    ComputeLineBbox(canvas, linePtr);
}

/*
 *--------------------------------------------------------------
 *
 * TranslateLine --
 *
 *    This procedure is called to move a line by a given amount.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    The position of the line is offset by (xDelta, yDelta), and
 *    the bounding box is updated in the generic part of the item
 *    structure.
 *
 *--------------------------------------------------------------
 */

static void
TranslateLine(canvas, itemPtr, deltaX, deltaY)
    Tk_Canvas canvas;               /* Canvas containing item. */
    Tk_Item *itemPtr;               /* Item that is being moved. */
    double deltaX, deltaY;          /* Amount by which item is to be
                               * moved. */
{
    LineItem *linePtr = (LineItem *) itemPtr;
    double *coordPtr;
    int i;

    for (i = 0, coordPtr = linePtr->coordPtr; i < linePtr->numPoints;
          i++, coordPtr += 2) {
      coordPtr[0] += deltaX;
      coordPtr[1] += deltaY;
    }
    if (linePtr->firstArrowPtr != NULL) {
      for (i = 0, coordPtr = linePtr->firstArrowPtr; i < PTS_IN_ARROW;
            i++, coordPtr += 2) {
          coordPtr[0] += deltaX;
          coordPtr[1] += deltaY;
      }
    }
    if (linePtr->lastArrowPtr != NULL) {
      for (i = 0, coordPtr = linePtr->lastArrowPtr; i < PTS_IN_ARROW;
            i++, coordPtr += 2) {
          coordPtr[0] += deltaX;
          coordPtr[1] += deltaY;
      }
    }
    ComputeLineBbox(canvas, linePtr);
}

/*
 *--------------------------------------------------------------
 *
 * ParseArrowShape --
 *
 *    This procedure is called back during option parsing to
 *    parse arrow shape information.
 *
 * Results:
 *    The return value is a standard Tcl result:  TCL_OK means
 *    that the arrow shape information was parsed ok, and
 *    TCL_ERROR means it couldn't be parsed.
 *
 * Side effects:
 *    Arrow information in recordPtr is updated.
 *
 *--------------------------------------------------------------
 */

      /* ARGSUSED */
static int
ParseArrowShape(clientData, interp, tkwin, value, recordPtr, offset)
    ClientData clientData;    /* Not used. */
    Tcl_Interp *interp;       /* Used for error reporting. */
    Tk_Window tkwin;          /* Not used. */
    char *value;        /* Textual specification of arrow shape. */
    char *recordPtr;          /* Pointer to item record in which to
                         * store arrow information. */
    int offset;               /* Offset of shape information in widget
                         * record. */
{
    LineItem *linePtr = (LineItem *) recordPtr;
    double a, b, c;
    int argc;
    char **argv = NULL;

    if (offset != Tk_Offset(LineItem, arrowShapeA)) {
      panic("ParseArrowShape received bogus offset");
    }

    if (Tcl_SplitList(interp, value, &argc, &argv) != TCL_OK) {
      syntaxError:
      Tcl_ResetResult(interp);
      Tcl_AppendResult(interp, "bad arrow shape \"", value,
            "\": must be list with three numbers", (char *) NULL);
      if (argv != NULL) {
          ckfree((char *) argv);
      }
      return TCL_ERROR;
    }
    if (argc != 3) {
      goto syntaxError;
    }
    if ((Tk_CanvasGetCoord(interp, linePtr->canvas, argv[0], &a) != TCL_OK)
          || (Tk_CanvasGetCoord(interp, linePtr->canvas, argv[1], &b)
            != TCL_OK)
          || (Tk_CanvasGetCoord(interp, linePtr->canvas, argv[2], &c)
            != TCL_OK)) {
      goto syntaxError;
    }
    linePtr->arrowShapeA = (float)a;
    linePtr->arrowShapeB = (float)b;
    linePtr->arrowShapeC = (float)c;
    ckfree((char *) argv);
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * PrintArrowShape --
 *
 *    This procedure is a callback invoked by the configuration
 *    code to return a printable value describing an arrow shape.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    None.
 *
 *--------------------------------------------------------------
 */

    /* ARGSUSED */
static char *
PrintArrowShape(clientData, tkwin, recordPtr, offset, freeProcPtr)
    ClientData clientData;    /* Not used. */
    Tk_Window tkwin;          /* Window associated with linePtr's widget. */
    char *recordPtr;          /* Pointer to item record containing current
                         * shape information. */
    int offset;               /* Offset of arrow information in record. */
    Tcl_FreeProc **freeProcPtr;     /* Store address of procedure to call to
                         * free string here. */
{
    LineItem *linePtr = (LineItem *) recordPtr;
    char *buffer;

    buffer = (char *) ckalloc(120);
    sprintf(buffer, "%.5g %.5g %.5g", linePtr->arrowShapeA,
          linePtr->arrowShapeB, linePtr->arrowShapeC);
    *freeProcPtr = TCL_DYNAMIC;
    return buffer;
}

/*
 *--------------------------------------------------------------
 *
 * ConfigureArrows --
 *
 *    If arrowheads have been requested for a line, this
 *    procedure makes arrangements for the arrowheads.
 *
 * Results:
 *    Always returns TCL_OK.
 *
 * Side effects:
 *    Information in linePtr is set up for one or two arrowheads.
 *    the firstArrowPtr and lastArrowPtr polygons are allocated
 *    and initialized, if need be, and the end points of the line
 *    are adjusted so that a thick line doesn't stick out past
 *    the arrowheads.
 *
 *--------------------------------------------------------------
 */

      /* ARGSUSED */
static int
ConfigureArrows(canvas, linePtr)
    Tk_Canvas canvas;               /* Canvas in which arrows will be
                               * displayed (interp and tkwin
                               * fields are needed). */
    LineItem *linePtr;              /* Item to configure for arrows. */
{
    double *poly, *coordPtr;
    double dx, dy, length, sinTheta, cosTheta, temp;
    double fracHeight;              /* Line width as fraction of
                               * arrowhead width. */
    double backup;                  /* Distance to backup end points
                               * so the line ends in the middle
                               * of the arrowhead. */
    double vertX, vertY;            /* Position of arrowhead vertex. */
    double shapeA, shapeB, shapeC;  /* Adjusted coordinates (see
                               * explanation below). */

    /*
     * The code below makes a tiny increase in the shape parameters
     * for the line.  This is a bit of a hack, but it seems to result
     * in displays that more closely approximate the specified parameters.
     * Without the adjustment, the arrows come out smaller than expected.
     */

    shapeA = linePtr->arrowShapeA + 0.001;
    shapeB = linePtr->arrowShapeB + 0.001;
    shapeC = linePtr->arrowShapeC + linePtr->width/2.0 + 0.001;

    /*
     * If there's an arrowhead on the first point of the line, compute
     * its polygon and adjust the first point of the line so that the
     * line doesn't stick out past the leading edge of the arrowhead.
     */

    fracHeight = (linePtr->width/2.0)/shapeC;
    backup = fracHeight*shapeB + shapeA*(1.0 - fracHeight)/2.0;
    if (linePtr->arrow != lastUid) {
      poly = linePtr->firstArrowPtr;
      if (poly == NULL) {
          poly = (double *) ckalloc((unsigned)
                (2*PTS_IN_ARROW*sizeof(double)));
          poly[0] = poly[10] = linePtr->coordPtr[0];
          poly[1] = poly[11] = linePtr->coordPtr[1];
          linePtr->firstArrowPtr = poly;
      }
      dx = poly[0] - linePtr->coordPtr[2];
      dy = poly[1] - linePtr->coordPtr[3];
      length = hypot(dx, dy);
      if (length == 0) {
          sinTheta = cosTheta = 0.0;
      } else {
          sinTheta = dy/length;
          cosTheta = dx/length;
      }
      vertX = poly[0] - shapeA*cosTheta;
      vertY = poly[1] - shapeA*sinTheta;
      temp = shapeC*sinTheta;
      poly[2] = poly[0] - shapeB*cosTheta + temp;
      poly[8] = poly[2] - 2*temp;
      temp = shapeC*cosTheta;
      poly[3] = poly[1] - shapeB*sinTheta - temp;
      poly[9] = poly[3] + 2*temp;
      poly[4] = poly[2]*fracHeight + vertX*(1.0-fracHeight);
      poly[5] = poly[3]*fracHeight + vertY*(1.0-fracHeight);
      poly[6] = poly[8]*fracHeight + vertX*(1.0-fracHeight);
      poly[7] = poly[9]*fracHeight + vertY*(1.0-fracHeight);

      /*
       * Polygon done.  Now move the first point towards the second so
       * that the corners at the end of the line are inside the
       * arrowhead.
       */

      linePtr->coordPtr[0] = poly[0] - backup*cosTheta;
      linePtr->coordPtr[1] = poly[1] - backup*sinTheta;
    }

    /*
     * Similar arrowhead calculation for the last point of the line.
     */

    if (linePtr->arrow != firstUid) {
      coordPtr = linePtr->coordPtr + 2*(linePtr->numPoints-2);
      poly = linePtr->lastArrowPtr;
      if (poly == NULL) {
          poly = (double *) ckalloc((unsigned)
                (2*PTS_IN_ARROW*sizeof(double)));
          poly[0] = poly[10] = coordPtr[2];
          poly[1] = poly[11] = coordPtr[3];
          linePtr->lastArrowPtr = poly;
      }
      dx = poly[0] - coordPtr[0];
      dy = poly[1] - coordPtr[1];
      length = hypot(dx, dy);
      if (length == 0) {
          sinTheta = cosTheta = 0.0;
      } else {
          sinTheta = dy/length;
          cosTheta = dx/length;
      }
      vertX = poly[0] - shapeA*cosTheta;
      vertY = poly[1] - shapeA*sinTheta;
      temp = shapeC*sinTheta;
      poly[2] = poly[0] - shapeB*cosTheta + temp;
      poly[8] = poly[2] - 2*temp;
      temp = shapeC*cosTheta;
      poly[3] = poly[1] - shapeB*sinTheta - temp;
      poly[9] = poly[3] + 2*temp;
      poly[4] = poly[2]*fracHeight + vertX*(1.0-fracHeight);
      poly[5] = poly[3]*fracHeight + vertY*(1.0-fracHeight);
      poly[6] = poly[8]*fracHeight + vertX*(1.0-fracHeight);
      poly[7] = poly[9]*fracHeight + vertY*(1.0-fracHeight);
      coordPtr[2] = poly[0] - backup*cosTheta;
      coordPtr[3] = poly[1] - backup*sinTheta;
    }

    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * LineToPostscript --
 *
 *    This procedure is called to generate Postscript for
 *    line items.
 *
 * Results:
 *    The return value is a standard Tcl result.  If an error
 *    occurs in generating Postscript then an error message is
 *    left in interp->result, replacing whatever used
 *    to be there.  If no error occurs, then Postscript for the
 *    item is appended to the result.
 *
 * Side effects:
 *    None.
 *
 *--------------------------------------------------------------
 */

static int
LineToPostscript(interp, canvas, itemPtr, prepass)
    Tcl_Interp *interp;             /* Leave Postscript or error message
                               * here. */
    Tk_Canvas canvas;               /* Information about overall canvas. */
    Tk_Item *itemPtr;               /* Item for which Postscript is
                               * wanted. */
    int prepass;              /* 1 means this is a prepass to
                               * collect font information;  0 means
                               * final Postscript is being created. */
{
    LineItem *linePtr = (LineItem *) itemPtr;
    char buffer[200];
    char *style;

    if (linePtr->fg == NULL) {
      return TCL_OK;
    }

    /*
     * Generate a path for the line's center-line (do this differently
     * for straight lines and smoothed lines).
     */

    if ((!linePtr->smooth) || (linePtr->numPoints <= 2)) {
      Tk_CanvasPsPath(interp, canvas, linePtr->coordPtr, linePtr->numPoints);
    } else {
      if (linePtr->fillStipple == None) {
          TkMakeBezierPostscript(interp, canvas, linePtr->coordPtr,
                linePtr->numPoints);
      } else {
          /*
           * Special hack: Postscript printers don't appear to be able
           * to turn a path drawn with "curveto"s into a clipping path
           * without exceeding resource limits, so TkMakeBezierPostscript
           * won't work for stippled curves.  Instead, generate all of
           * the intermediate points here and output them into the
           * Postscript file with "lineto"s instead.
           */

          double staticPoints[2*MAX_STATIC_POINTS];
          double *pointPtr;
          int numPoints;

          numPoints = 1 + linePtr->numPoints*linePtr->splineSteps;
          pointPtr = staticPoints;
          if (numPoints > MAX_STATIC_POINTS) {
            pointPtr = (double *) ckalloc((unsigned)
                  (numPoints * 2 * sizeof(double)));
          }
          numPoints = TkMakeBezierCurve(canvas, linePtr->coordPtr,
                linePtr->numPoints, linePtr->splineSteps, (XPoint *) NULL,
                pointPtr);
          Tk_CanvasPsPath(interp, canvas, pointPtr, numPoints);
          if (pointPtr != staticPoints) {
            ckfree((char *) pointPtr);
          }
      }
    }

    /*
     * Set other line-drawing parameters and stroke out the line.
     */

    sprintf(buffer, "%d setlinewidth\n", linePtr->width);
    Tcl_AppendResult(interp, buffer, (char *) NULL);
    style = "0 setlinecap\n";
    if (linePtr->capStyle == CapRound) {
      style = "1 setlinecap\n";
    } else if (linePtr->capStyle == CapProjecting) {
      style = "2 setlinecap\n";
    }
    Tcl_AppendResult(interp, style, (char *) NULL);
    style = "0 setlinejoin\n";
    if (linePtr->joinStyle == JoinRound) {
      style = "1 setlinejoin\n";
    } else if (linePtr->joinStyle == JoinBevel) {
      style = "2 setlinejoin\n";
    }
    Tcl_AppendResult(interp, style, (char *) NULL);
    if (Tk_CanvasPsColor(interp, canvas, linePtr->fg) != TCL_OK) {
      return TCL_ERROR;
    };
    if (linePtr->fillStipple != None) {
      Tcl_AppendResult(interp, "StrokeClip ", (char *) NULL);
      if (Tk_CanvasPsStipple(interp, canvas, linePtr->fillStipple)
            != TCL_OK) {
          return TCL_ERROR;
      }
    } else {
      Tcl_AppendResult(interp, "stroke\n", (char *) NULL);
    }

    /*
     * Output polygons for the arrowheads, if there are any.
     */

    if (linePtr->firstArrowPtr != NULL) {
      if (linePtr->fillStipple != None) {
          Tcl_AppendResult(interp, "grestore gsave\n",
                (char *) NULL);
      }
      if (ArrowheadPostscript(interp, canvas, linePtr,
            linePtr->firstArrowPtr) != TCL_OK) {
          return TCL_ERROR;
      }
    }
    if (linePtr->lastArrowPtr != NULL) {
      if (linePtr->fillStipple != None) {
          Tcl_AppendResult(interp, "grestore gsave\n", (char *) NULL);
      }
      if (ArrowheadPostscript(interp, canvas, linePtr,
            linePtr->lastArrowPtr) != TCL_OK) {
          return TCL_ERROR;
      }
    }
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * ArrowheadPostscript --
 *
 *    This procedure is called to generate Postscript for
 *    an arrowhead for a line item.
 *
 * Results:
 *    The return value is a standard Tcl result.  If an error
 *    occurs in generating Postscript then an error message is
 *    left in interp->result, replacing whatever used
 *    to be there.  If no error occurs, then Postscript for the
 *    arrowhead is appended to the result.
 *
 * Side effects:
 *    None.
 *
 *--------------------------------------------------------------
 */

static int
ArrowheadPostscript(interp, canvas, linePtr, arrowPtr)
    Tcl_Interp *interp;             /* Leave Postscript or error message
                               * here. */
    Tk_Canvas canvas;               /* Information about overall canvas. */
    LineItem *linePtr;              /* Line item for which Postscript is
                               * being generated. */
    double *arrowPtr;               /* Pointer to first of five points
                               * describing arrowhead polygon. */
{
    Tk_CanvasPsPath(interp, canvas, arrowPtr, PTS_IN_ARROW);
    if (linePtr->fillStipple != None) {
      Tcl_AppendResult(interp, "clip ", (char *) NULL);
      if (Tk_CanvasPsStipple(interp, canvas, linePtr->fillStipple)
            != TCL_OK) {
          return TCL_ERROR;
      }
    } else {
      Tcl_AppendResult(interp, "fill\n", (char *) NULL);
    }
    return TCL_OK;
}

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