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tkCanvPoly.c

/* 
 * tkCanvPoly.c --
 *
 *    This file implements polygon items for canvas widgets.
 *
 * Copyright (c) 1991-1994 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tkCanvPoly.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 polygon item.
 */

typedef struct PolygonItem  {
    Tk_Item header;           /* Generic stuff that's the same for all
                         * types.  MUST BE FIRST IN STRUCTURE. */
    int numPoints;            /* Number of points in polygon (always >= 3).
                         * Polygon is always closed. */
    int pointsAllocated;      /* Number of points for which space is
                         * allocated at *coordPtr. */
    double *coordPtr;         /* Pointer to malloc-ed array containing
                         * x- and y-coords of all points in polygon.
                         * X-coords are even-valued indices, y-coords
                         * are corresponding odd-valued indices. */
    int width;                /* Width of outline. */
    XColor *outlineColor;     /* Color for outline. */
    GC outlineGC;       /* Graphics context for drawing outline. */
    XColor *fillColor;        /* Foreground color for polygon. */
    Pixmap fillStipple;       /* Stipple bitmap for filling polygon. */
    GC fillGC;                /* Graphics context for filling polygon. */
    int smooth;               /* Non-zero means draw shape smoothed (i.e.
                         * with Bezier splines). */
    int splineSteps;          /* Number of steps in each spline segment. */
    int autoClosed;           /* Zero means the given polygon was closed,
                           one means that we auto closed it. */
} PolygonItem;

/*
 * Information used for parsing configuration specs:
 */

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

static Tk_ConfigSpec configSpecs[] = {
    {TK_CONFIG_COLOR, "-fill", (char *) NULL, (char *) NULL,
      "black", Tk_Offset(PolygonItem, fillColor), TK_CONFIG_NULL_OK},
    {TK_CONFIG_COLOR, "-outline", (char *) NULL, (char *) NULL,
      (char *) NULL, Tk_Offset(PolygonItem, outlineColor), TK_CONFIG_NULL_OK},
    {TK_CONFIG_BOOLEAN, "-smooth", (char *) NULL, (char *) NULL,
      "0", Tk_Offset(PolygonItem, smooth), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_INT, "-splinesteps", (char *) NULL, (char *) NULL,
      "12", Tk_Offset(PolygonItem, splineSteps), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_BITMAP, "-stipple", (char *) NULL, (char *) NULL,
      (char *) NULL, Tk_Offset(PolygonItem, 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(PolygonItem, width), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_END, (char *) NULL, (char *) NULL, (char *) NULL,
      (char *) NULL, 0, 0}
};

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

static void       ComputePolygonBbox _ANSI_ARGS_((Tk_Canvas canvas,
                      PolygonItem *polyPtr));
static int        ConfigurePolygon _ANSI_ARGS_((Tcl_Interp *interp,
                      Tk_Canvas canvas, Tk_Item *itemPtr, int argc,
                      char **argv, int flags));
static int        CreatePolygon _ANSI_ARGS_((Tcl_Interp *interp,
                      Tk_Canvas canvas, struct Tk_Item *itemPtr,
                      int argc, char **argv));
static void       DeletePolygon _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr,  Display *display));
static void       DisplayPolygon _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, Display *display, Drawable dst,
                      int x, int y, int width, int height));
static int        PolygonCoords _ANSI_ARGS_((Tcl_Interp *interp,
                      Tk_Canvas canvas, Tk_Item *itemPtr,
                      int argc, char **argv));
static int        PolygonToArea _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, double *rectPtr));
static double           PolygonToPoint _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, double *pointPtr));
static int        PolygonToPostscript _ANSI_ARGS_((Tcl_Interp *interp,
                      Tk_Canvas canvas, Tk_Item *itemPtr, int prepass));
static void       ScalePolygon _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, double originX, double originY,
                      double scaleX, double scaleY));
static void       TranslatePolygon _ANSI_ARGS_((Tk_Canvas canvas,
                      Tk_Item *itemPtr, double deltaX, double deltaY));

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

Tk_ItemType tkPolygonType = {
    "polygon",                      /* name */
    sizeof(PolygonItem),            /* itemSize */
    CreatePolygon,                  /* createProc */
    configSpecs,              /* configSpecs */
    ConfigurePolygon,               /* configureProc */
    PolygonCoords,                  /* coordProc */
    DeletePolygon,                  /* deleteProc */
    DisplayPolygon,                 /* displayProc */
    0,                              /* alwaysRedraw */
    PolygonToPoint,                 /* pointProc */
    PolygonToArea,                  /* areaProc */
    PolygonToPostscript,            /* postscriptProc */
    ScalePolygon,             /* scaleProc */
    TranslatePolygon,               /* 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 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

/*
 *--------------------------------------------------------------
 *
 * CreatePolygon --
 *
 *    This procedure is invoked to create a new polygon 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 polygon item is created.
 *
 *--------------------------------------------------------------
 */

static int
CreatePolygon(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 polygon. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    int i;

    if (argc < 6) {
      Tcl_AppendResult(interp, "wrong # args: should be \"",
            Tk_PathName(Tk_CanvasTkwin(canvas)), " create ",
            itemPtr->typePtr->name,
            " x1 y1 x2 y2 x3 y3 ?x4 y4 ...? ?options?\"", (char *) NULL);
      return TCL_ERROR;
    }

    /*
     * Carry out initialization that is needed in order to clean
     * up after errors during the the remainder of this procedure.
     */

    polyPtr->numPoints = 0;
    polyPtr->pointsAllocated = 0;
    polyPtr->coordPtr = NULL;
    polyPtr->width = 1;
    polyPtr->outlineColor = NULL;
    polyPtr->outlineGC = None;
    polyPtr->fillColor = NULL;
    polyPtr->fillStipple = None;
    polyPtr->fillGC = None;
    polyPtr->smooth = 0;
    polyPtr->splineSteps = 12;
    polyPtr->autoClosed = 0;

    /*
     * 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] != '-') || (!isdigit(UCHAR(argv[i][1]))))) {
          break;
      }
    }
    if (PolygonCoords(interp, canvas, itemPtr, i, argv) != TCL_OK) {
      goto error;
    }

    if (ConfigurePolygon(interp, canvas, itemPtr, argc-i, argv+i, 0)
          == TCL_OK) {
      return TCL_OK;
    }

    error:
    DeletePolygon(canvas, itemPtr, Tk_Display(Tk_CanvasTkwin(canvas)));
    return TCL_ERROR;
}

/*
 *--------------------------------------------------------------
 *
 * PolygonCoords --
 *
 *    This procedure is invoked to process the "coords" widget
 *    command on polygons.  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
PolygonCoords(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, ... */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    char buffer[TCL_DOUBLE_SPACE];
    int i, numPoints;

    if (argc == 0) {
      /*
       * Print the coords used to create the polygon.  If we auto
       * closed the polygon then we don't report the last point.
       */
      for (i = 0; i < 2*(polyPtr->numPoints - polyPtr->autoClosed); i++) {
          Tcl_PrintDouble(interp, polyPtr->coordPtr[i], buffer);
          Tcl_AppendElement(interp, buffer);
      }
    } else if (argc < 6) {
      Tcl_AppendResult(interp,
            "too few coordinates for polygon: must have at least 6",
            (char *) NULL);
      return TCL_ERROR;
    } else if (argc & 1) {
      Tcl_AppendResult(interp,
            "odd number of coordinates specified for polygon",
            (char *) NULL);
      return TCL_ERROR;
    } else {
      numPoints = argc/2;
      if (polyPtr->pointsAllocated <= numPoints) {
          if (polyPtr->coordPtr != NULL) {
            ckfree((char *) polyPtr->coordPtr);
          }

          /*
           * One extra point gets allocated here, just in case we have
           * to add another point to close the polygon.
           */

          polyPtr->coordPtr = (double *) ckalloc((unsigned)
                (sizeof(double) * (argc+2)));
          polyPtr->pointsAllocated = numPoints+1;
      }
      for (i = argc-1; i >= 0; i--) {
          if (Tk_CanvasGetCoord(interp, canvas, argv[i],
                &polyPtr->coordPtr[i]) != TCL_OK) {
            return TCL_ERROR;
          }
      }
      polyPtr->numPoints = numPoints;
      polyPtr->autoClosed = 0;
    
      /*
       * Close the polygon if it isn't already closed.
       */
    
      if ((polyPtr->coordPtr[argc-2] != polyPtr->coordPtr[0])
            || (polyPtr->coordPtr[argc-1] != polyPtr->coordPtr[1])) {
          polyPtr->autoClosed = 1;
          polyPtr->numPoints++;
          polyPtr->coordPtr[argc] = polyPtr->coordPtr[0];
          polyPtr->coordPtr[argc+1] = polyPtr->coordPtr[1];
      }
      ComputePolygonBbox(canvas, polyPtr);
    }
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * ConfigurePolygon --
 *
 *    This procedure is invoked to configure various aspects
 *    of a polygon 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
ConfigurePolygon(interp, canvas, itemPtr, argc, argv, flags)
    Tcl_Interp *interp;       /* Interpreter for error reporting. */
    Tk_Canvas canvas;         /* Canvas containing itemPtr. */
    Tk_Item *itemPtr;         /* Polygon 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. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    XGCValues gcValues;
    GC newGC;
    unsigned long mask;
    Tk_Window tkwin;

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

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

    if (polyPtr->width < 1) {
      polyPtr->width = 1;
    }
    if (polyPtr->outlineColor == NULL) {
      newGC = None;
    } else {
      gcValues.foreground = polyPtr->outlineColor->pixel;
      gcValues.line_width = polyPtr->width;
      gcValues.cap_style = CapRound;
      gcValues.join_style = JoinRound;
      mask = GCForeground|GCLineWidth|GCCapStyle|GCJoinStyle;
      newGC = Tk_GetGC(tkwin, mask, &gcValues);
    }
    if (polyPtr->outlineGC != None) {
      Tk_FreeGC(Tk_Display(tkwin), polyPtr->outlineGC);
    }
    polyPtr->outlineGC = newGC;

    if (polyPtr->fillColor == NULL) {
      newGC = None;
    } else {
      gcValues.foreground = polyPtr->fillColor->pixel;
      mask = GCForeground;
      if (polyPtr->fillStipple != None) {
          gcValues.stipple = polyPtr->fillStipple;
          gcValues.fill_style = FillStippled;
          mask |= GCStipple|GCFillStyle;
      }
      newGC = Tk_GetGC(tkwin, mask, &gcValues);
    }
    if (polyPtr->fillGC != None) {
      Tk_FreeGC(Tk_Display(tkwin), polyPtr->fillGC);
    }
    polyPtr->fillGC = newGC;

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

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

    ComputePolygonBbox(canvas, polyPtr);
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * DeletePolygon --
 *
 *    This procedure is called to clean up the data structure
 *    associated with a polygon item.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    Resources associated with itemPtr are released.
 *
 *--------------------------------------------------------------
 */

static void
DeletePolygon(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. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;

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

static void
ComputePolygonBbox(canvas, polyPtr)
    Tk_Canvas canvas;               /* Canvas that contains item. */
    PolygonItem *polyPtr;           /* Item whose bbox is to be
                               * recomputed. */
{
    double *coordPtr;
    int i;

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

    for (i = 1, coordPtr = polyPtr->coordPtr+2; i < polyPtr->numPoints;
          i++, coordPtr += 2) {
      TkIncludePoint((Tk_Item *) polyPtr, coordPtr);
    }

    /*
     * Expand bounding box in all directions to account for the outline,
     * which can stick out beyond the polygon.  Add one extra pixel of
     * fudge, just in case X rounds differently than we do.
     */

    i = (polyPtr->width+1)/2 + 1;
    polyPtr->header.x1 -= i;
    polyPtr->header.x2 += i;
    polyPtr->header.y1 -= i;
    polyPtr->header.y2 += i;
}

/*
 *--------------------------------------------------------------
 *
 * TkFillPolygon --
 *
 *    This procedure is invoked to convert a polygon to screen
 *    coordinates and display it using a particular GC.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    ItemPtr is drawn in drawable using the transformation
 *    information in canvas.
 *
 *--------------------------------------------------------------
 */

void
TkFillPolygon(canvas, coordPtr, numPoints, display, drawable, gc, outlineGC)
    Tk_Canvas canvas;               /* Canvas whose coordinate system
                               * is to be used for drawing. */
    double *coordPtr;               /* Array of coordinates for polygon:
                               * x1, y1, x2, y2, .... */
    int numPoints;                  /* Twice this many coordinates are
                               * present at *coordPtr. */
    Display *display;               /* Display on which to draw polygon. */
    Drawable drawable;              /* Pixmap or window in which to draw
                               * polygon. */
    GC gc;                    /* Graphics context for drawing. */
    GC outlineGC;             /* If not None, use this to draw an
                               * outline around the polygon after
                               * filling it. */
{
    XPoint staticPoints[MAX_STATIC_POINTS];
    XPoint *pointPtr;
    XPoint *pPtr;
    int i;

    /*
     * Build up an array of points in screen coordinates.  Use a
     * static array unless the polygon has an enormous number of points;
     * in this case, dynamically allocate an array.
     */

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

    for (i = 0, pPtr = pointPtr; i < numPoints; i += 1, coordPtr += 2, pPtr++) {
      Tk_CanvasDrawableCoords(canvas, coordPtr[0], coordPtr[1], &pPtr->x,
            &pPtr->y);
    }

    /*
     * Display polygon, then free up polygon storage if it was dynamically
     * allocated.
     */

    if (gc != None) {
      XFillPolygon(display, drawable, gc, pointPtr, numPoints, Complex,
            CoordModeOrigin);
    }
    if (outlineGC != None) {
      XDrawLines(display, drawable, outlineGC, pointPtr,
          numPoints, CoordModeOrigin);
    }
    if (pointPtr != staticPoints) {
      ckfree((char *) pointPtr);
    }
}

/*
 *--------------------------------------------------------------
 *
 * DisplayPolygon --
 *
 *    This procedure is invoked to draw a polygon item in a given
 *    drawable.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    ItemPtr is drawn in drawable using the transformation
 *    information in canvas.
 *
 *--------------------------------------------------------------
 */

static void
DisplayPolygon(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). */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;

    if ((polyPtr->fillGC == None) && (polyPtr->outlineGC == None)) {
      return;
    }

    /*
     * 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 ((polyPtr->fillStipple != None) && (polyPtr->fillGC != None)) {
      Tk_CanvasSetStippleOrigin(canvas, polyPtr->fillGC);
    }

    if (!polyPtr->smooth) {
      TkFillPolygon(canvas, polyPtr->coordPtr, polyPtr->numPoints,
            display, drawable, polyPtr->fillGC, polyPtr->outlineGC);
    } else {
      int numPoints;
      XPoint staticPoints[MAX_STATIC_POINTS];
      XPoint *pointPtr;

      /*
       * This is a smoothed polygon.  Display using a set of generated
       * spline points rather than the original points.
       */

      numPoints = 1 + polyPtr->numPoints*polyPtr->splineSteps;
      if (numPoints <= MAX_STATIC_POINTS) {
          pointPtr = staticPoints;
      } else {
          pointPtr = (XPoint *) ckalloc((unsigned)
                (numPoints * sizeof(XPoint)));
      }
      numPoints = TkMakeBezierCurve(canvas, polyPtr->coordPtr,
            polyPtr->numPoints, polyPtr->splineSteps, pointPtr,
            (double *) NULL);
      if (polyPtr->fillGC != None) {
          XFillPolygon(display, drawable, polyPtr->fillGC, pointPtr,
                numPoints, Complex, CoordModeOrigin);
      }
      if (polyPtr->outlineGC != None) {
          XDrawLines(display, drawable, polyPtr->outlineGC, pointPtr,
                numPoints, CoordModeOrigin);
      }
      if (pointPtr != staticPoints) {
          ckfree((char *) pointPtr);
      }
    }
    if ((polyPtr->fillStipple != None) && (polyPtr->fillGC != None)) {
      XSetTSOrigin(display, polyPtr->fillGC, 0, 0);
    }
}

/*
 *--------------------------------------------------------------
 *
 * PolygonToPoint --
 *
 *    Computes the distance from a given point to a given
 *    polygon, 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 polygon.  If the
 *    point isn't inside the polygon then the return value is the
 *    distance from the point to the polygon.
 *
 * Side effects:
 *    None.
 *
 *--------------------------------------------------------------
 */

      /* ARGSUSED */
static double
PolygonToPoint(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. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    double *coordPtr, distance;
    double staticSpace[2*MAX_STATIC_POINTS];
    int numPoints;

    if (!polyPtr->smooth) {
      distance = TkPolygonToPoint(polyPtr->coordPtr, polyPtr->numPoints,
            pointPtr);
    } else {
      /*
       * Smoothed polygon.  Generate a new set of points and use them
       * for comparison.
       */
    
      numPoints = 1 + polyPtr->numPoints*polyPtr->splineSteps;
      if (numPoints <= MAX_STATIC_POINTS) {
          coordPtr = staticSpace;
      } else {
          coordPtr = (double *) ckalloc((unsigned)
                (2*numPoints*sizeof(double)));
      }
      numPoints = TkMakeBezierCurve(canvas, polyPtr->coordPtr,
            polyPtr->numPoints, polyPtr->splineSteps, (XPoint *) NULL,
            coordPtr);
      distance = TkPolygonToPoint(coordPtr, numPoints, pointPtr);
      if (coordPtr != staticSpace) {
          ckfree((char *) coordPtr);
      }
    }
    if (polyPtr->outlineColor != NULL) {
      distance -= polyPtr->width/2.0;
      if (distance < 0) {
          distance = 0;
      }
    }
    return distance;
}

/*
 *--------------------------------------------------------------
 *
 * PolygonToArea --
 *
 *    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
 *    given by rectPtr, 0 if it overlaps, and 1 if it is entirely
 *    inside the given area.
 *
 * Side effects:
 *    None.
 *
 *--------------------------------------------------------------
 */

      /* ARGSUSED */
static int
PolygonToArea(canvas, itemPtr, rectPtr)
    Tk_Canvas canvas;         /* Canvas containing item. */
    Tk_Item *itemPtr;         /* Item to check against polygon. */
    double *rectPtr;          /* Pointer to array of four coordinates
                         * (x1, y1, x2, y2) describing rectangular
                         * area.  */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    double *coordPtr, rect2[4], halfWidth;
    double staticSpace[2*MAX_STATIC_POINTS];
    int numPoints, result;

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

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

    if (polyPtr->width <= 1) {
      /*
       * The outline of the polygon doesn't stick out, so we can
       * do a simple check.
       */

      result = TkPolygonToArea(coordPtr, numPoints, rectPtr);
    } else {
      /*
       * The polygon has a wide outline, so the check is more complicated.
       * First, check the line segments to see if they overlap the area.
       */

      result = TkThickPolyLineToArea(coordPtr, numPoints, 
          (double) polyPtr->width, CapRound, JoinRound, rectPtr);
      if (result >= 0) {
          goto done;
      }

      /*
       * There is no overlap between the polygon's outline and the
       * rectangle.  This means either the rectangle is entirely outside
       * the polygon or entirely inside.  To tell the difference,
       * see whether the polygon (with 0 outline width) overlaps the
       * rectangle bloated by half the outline width.
       */

      halfWidth = polyPtr->width/2.0;
      rect2[0] = rectPtr[0] - halfWidth;
      rect2[1] = rectPtr[1] - halfWidth;
      rect2[2] = rectPtr[2] + halfWidth;
      rect2[3] = rectPtr[3] + halfWidth;
      if (TkPolygonToArea(coordPtr, numPoints, rect2) == -1) {
          result = -1;
      } else {
          result = 0;
      }
    }

    done:
    if ((coordPtr != staticSpace) && (coordPtr != polyPtr->coordPtr)) {
      ckfree((char *) coordPtr);
    }
    return result;
}

/*
 *--------------------------------------------------------------
 *
 * ScalePolygon --
 *
 *    This procedure is invoked to rescale a polygon item.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    The polygon 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
ScalePolygon(canvas, itemPtr, originX, originY, scaleX, scaleY)
    Tk_Canvas canvas;               /* Canvas containing polygon. */
    Tk_Item *itemPtr;               /* Polygon 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. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    double *coordPtr;
    int i;

    for (i = 0, coordPtr = polyPtr->coordPtr; i < polyPtr->numPoints;
          i++, coordPtr += 2) {
      *coordPtr = originX + scaleX*(*coordPtr - originX);
      coordPtr[1] = originY + scaleY*(coordPtr[1] - originY);
    }
    ComputePolygonBbox(canvas, polyPtr);
}

/*
 *--------------------------------------------------------------
 *
 * TranslatePolygon --
 *
 *    This procedure is called to move a polygon by a given
 *    amount.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    The position of the polygon is offset by (xDelta, yDelta),
 *    and the bounding box is updated in the generic part of the
 *    item structure.
 *
 *--------------------------------------------------------------
 */

static void
TranslatePolygon(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. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    double *coordPtr;
    int i;

    for (i = 0, coordPtr = polyPtr->coordPtr; i < polyPtr->numPoints;
          i++, coordPtr += 2) {
      *coordPtr += deltaX;
      coordPtr[1] += deltaY;
    }
    ComputePolygonBbox(canvas, polyPtr);
}

/*
 *--------------------------------------------------------------
 *
 * PolygonToPostscript --
 *
 *    This procedure is called to generate Postscript for
 *    polygon 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
PolygonToPostscript(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. */
{
    char string[100];
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;

    /*
     * Fill the area of the polygon.
     */

    if (polyPtr->fillColor != NULL) {
      if (!polyPtr->smooth) {
          Tk_CanvasPsPath(interp, canvas, polyPtr->coordPtr,
                polyPtr->numPoints);
      } else {
          TkMakeBezierPostscript(interp, canvas, polyPtr->coordPtr,
                polyPtr->numPoints);
      }
      if (Tk_CanvasPsColor(interp, canvas, polyPtr->fillColor) != TCL_OK) {
          return TCL_ERROR;
      }
      if (polyPtr->fillStipple != None) {
          Tcl_AppendResult(interp, "eoclip ", (char *) NULL);
          if (Tk_CanvasPsStipple(interp, canvas, polyPtr->fillStipple)
                != TCL_OK) {
            return TCL_ERROR;
          }
          if (polyPtr->outlineColor != NULL) {
            Tcl_AppendResult(interp, "grestore gsave\n", (char *) NULL);
          }
      } else {
          Tcl_AppendResult(interp, "eofill\n", (char *) NULL);
      }
    }

    /*
     * Now draw the outline, if there is one.
     */

    if (polyPtr->outlineColor != NULL) {
      if (!polyPtr->smooth) {
          Tk_CanvasPsPath(interp, canvas, polyPtr->coordPtr,
            polyPtr->numPoints);
      } else {
          TkMakeBezierPostscript(interp, canvas, polyPtr->coordPtr,
            polyPtr->numPoints);
      }

      sprintf(string, "%d setlinewidth\n", polyPtr->width);
      Tcl_AppendResult(interp, string,
            "1 setlinecap\n1 setlinejoin\n", (char *) NULL);
      if (Tk_CanvasPsColor(interp, canvas, polyPtr->outlineColor)
            != TCL_OK) {
          return TCL_ERROR;
      }
      Tcl_AppendResult(interp, "stroke\n", (char *) NULL);
    }
    return TCL_OK;
}

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