path: root/generic/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.
 * Copyright (c) 1998-2000 Ajuba Solutions.
 *
 * 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 1.28 2010/11/19 14:48:00 nijtmans Exp $
 */

#include "tkInt.h"
#include "tkCanvas.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. */
    Tk_Outline outline;		/* Outline structure */
    int numPoints;		/* Number of points in polygon. 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 joinStyle;		/* Join style for outline */
    Tk_TSOffset tsoffset;
    XColor *fillColor;		/* Foreground color for polygon. */
    XColor *activeFillColor;	/* Foreground color for polygon if state is
				 * active. */
    XColor *disabledFillColor;	/* Foreground color for polygon if state is
				 * disabled. */
    Pixmap fillStipple;		/* Stipple bitmap for filling polygon. */
    Pixmap activeFillStipple;	/* Stipple bitmap for filling polygon if state
				 * is active. */
    Pixmap disabledFillStipple;	/* Stipple bitmap for filling polygon if state
				 * is disabled. */
    GC fillGC;			/* Graphics context for filling polygon. */
    const Tk_SmoothMethod *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 const Tk_CustomOption smoothOption = {
    TkSmoothParseProc, TkSmoothPrintProc, NULL
};
static const Tk_CustomOption stateOption = {
    TkStateParseProc, TkStatePrintProc, INT2PTR(2)
};
static const Tk_CustomOption tagsOption = {
    Tk_CanvasTagsParseProc, Tk_CanvasTagsPrintProc, NULL
};
static const Tk_CustomOption dashOption = {
    TkCanvasDashParseProc, TkCanvasDashPrintProc, NULL
};
static const Tk_CustomOption offsetOption = {
    TkOffsetParseProc, TkOffsetPrintProc,
    INT2PTR(TK_OFFSET_RELATIVE|TK_OFFSET_INDEX)
};
static const Tk_CustomOption pixelOption = {
    TkPixelParseProc, TkPixelPrintProc, NULL
};

static const Tk_ConfigSpec configSpecs[] = {
    {TK_CONFIG_CUSTOM, "-activedash", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, outline.activeDash),
	TK_CONFIG_NULL_OK, &dashOption},
    {TK_CONFIG_COLOR, "-activefill", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, activeFillColor), TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_COLOR, "-activeoutline", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, outline.activeColor), TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_BITMAP, "-activeoutlinestipple", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, outline.activeStipple),
	TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_BITMAP, "-activestipple", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, activeFillStipple), TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_CUSTOM, "-activewidth", NULL, NULL,
	"0.0", Tk_Offset(PolygonItem, outline.activeWidth),
	TK_CONFIG_DONT_SET_DEFAULT, &pixelOption},
    {TK_CONFIG_CUSTOM, "-dash", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, outline.dash),
	TK_CONFIG_NULL_OK, &dashOption},
    {TK_CONFIG_PIXELS, "-dashoffset", NULL, NULL,
	"0", Tk_Offset(PolygonItem, outline.offset),
	TK_CONFIG_DONT_SET_DEFAULT, NULL},
    {TK_CONFIG_CUSTOM, "-disableddash", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, outline.disabledDash),
	TK_CONFIG_NULL_OK, &dashOption},
    {TK_CONFIG_COLOR, "-disabledfill", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, disabledFillColor), TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_COLOR, "-disabledoutline", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, outline.disabledColor),
	TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_BITMAP, "-disabledoutlinestipple", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, outline.disabledStipple),
	TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_BITMAP, "-disabledstipple", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, disabledFillStipple), TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_CUSTOM, "-disabledwidth", NULL, NULL,
	"0.0", Tk_Offset(PolygonItem, outline.disabledWidth),
	TK_CONFIG_DONT_SET_DEFAULT, &pixelOption},
    {TK_CONFIG_COLOR, "-fill", NULL, NULL,
	"black", Tk_Offset(PolygonItem, fillColor), TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_JOIN_STYLE, "-joinstyle", NULL, NULL,
	"round", Tk_Offset(PolygonItem, joinStyle), TK_CONFIG_DONT_SET_DEFAULT, NULL},
    {TK_CONFIG_CUSTOM, "-offset", NULL, NULL,
	"0,0", Tk_Offset(PolygonItem, tsoffset),
	TK_CONFIG_NULL_OK, &offsetOption},
    {TK_CONFIG_COLOR, "-outline", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, outline.color), TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_CUSTOM, "-outlineoffset", NULL, NULL,
	"0,0", Tk_Offset(PolygonItem, outline.tsoffset),
	TK_CONFIG_NULL_OK, &offsetOption},
    {TK_CONFIG_BITMAP, "-outlinestipple", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, outline.stipple), TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_CUSTOM, "-smooth", NULL, NULL,
	"0", Tk_Offset(PolygonItem, smooth),
	TK_CONFIG_DONT_SET_DEFAULT, &smoothOption},
    {TK_CONFIG_INT, "-splinesteps", NULL, NULL,
	"12", Tk_Offset(PolygonItem, splineSteps), TK_CONFIG_DONT_SET_DEFAULT, NULL},
    {TK_CONFIG_CUSTOM, "-state", NULL, NULL,
	NULL, Tk_Offset(Tk_Item, state), TK_CONFIG_NULL_OK, &stateOption},
    {TK_CONFIG_BITMAP, "-stipple", NULL, NULL,
	NULL, Tk_Offset(PolygonItem, fillStipple), TK_CONFIG_NULL_OK, NULL},
    {TK_CONFIG_CUSTOM, "-tags", NULL, NULL,
	NULL, 0, TK_CONFIG_NULL_OK, &tagsOption},
    {TK_CONFIG_CUSTOM, "-width", NULL, NULL,
	"1.0", Tk_Offset(PolygonItem, outline.width),
	TK_CONFIG_DONT_SET_DEFAULT, &pixelOption},
    {TK_CONFIG_END, NULL, NULL, NULL, NULL, 0, 0, NULL}
};

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

static void		ComputePolygonBbox(Tk_Canvas canvas,
			    PolygonItem *polyPtr);
static int		ConfigurePolygon(Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr, int objc,
			    Tcl_Obj *const objv[], int flags);
static int		CreatePolygon(Tcl_Interp *interp,
			    Tk_Canvas canvas, struct Tk_Item *itemPtr,
			    int objc, Tcl_Obj *const objv[]);
static void		DeletePolygon(Tk_Canvas canvas,
			    Tk_Item *itemPtr,  Display *display);
static void		DisplayPolygon(Tk_Canvas canvas,
			    Tk_Item *itemPtr, Display *display, Drawable dst,
			    int x, int y, int width, int height);
static int		GetPolygonIndex(Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr,
			    Tcl_Obj *obj, int *indexPtr);
static int		PolygonCoords(Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr,
			    int objc, Tcl_Obj *const objv[]);
static void		PolygonDeleteCoords(Tk_Canvas canvas,
			    Tk_Item *itemPtr, int first, int last);
static void		PolygonInsert(Tk_Canvas canvas,
			    Tk_Item *itemPtr, int beforeThis, Tcl_Obj *obj);
static int		PolygonToArea(Tk_Canvas canvas,
			    Tk_Item *itemPtr, double *rectPtr);
static double		PolygonToPoint(Tk_Canvas canvas,
			    Tk_Item *itemPtr, double *pointPtr);
static int		PolygonToPostscript(Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr, int prepass);
static void		ScalePolygon(Tk_Canvas canvas,
			    Tk_Item *itemPtr, double originX, double originY,
			    double scaleX, double scaleY);
static void		TranslatePolygon(Tk_Canvas canvas,
			    Tk_Item *itemPtr, double deltaX, double deltaY);

/*
 * The structures below defines the polygon item type by means of functions
 * 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 */
    TK_CONFIG_OBJS | TK_MOVABLE_POINTS,	/* flags */
    PolygonToPoint,			/* pointProc */
    PolygonToArea,			/* areaProc */
    PolygonToPostscript,		/* postscriptProc */
    ScalePolygon,			/* scaleProc */
    TranslatePolygon,			/* translateProc */
    GetPolygonIndex,	/* indexProc */
    NULL,				/* icursorProc */
    NULL,				/* selectionProc */
    PolygonInsert,		/* insertProc */
    PolygonDeleteCoords,		/* dTextProc */
    NULL,				/* nextPtr */
    NULL, 0, NULL, 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

/*
 *--------------------------------------------------------------
 *
 * CreatePolygon --
 *
 *	This function 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 the interp's 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(
    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 objc,			/* Number of arguments in objv. */
    Tcl_Obj *const objv[])	/* Arguments describing polygon. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    int i;

    if (objc == 0) {
	Tcl_Panic("canvas did not pass any coords");
    }

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

    Tk_CreateOutline(&polyPtr->outline);
    polyPtr->numPoints = 0;
    polyPtr->pointsAllocated = 0;
    polyPtr->coordPtr = NULL;
    polyPtr->joinStyle = JoinRound;
    polyPtr->tsoffset.flags = 0;
    polyPtr->tsoffset.xoffset = 0;
    polyPtr->tsoffset.yoffset = 0;
    polyPtr->fillColor = NULL;
    polyPtr->activeFillColor = NULL;
    polyPtr->disabledFillColor = NULL;
    polyPtr->fillStipple = None;
    polyPtr->activeFillStipple = None;
    polyPtr->disabledFillStipple = None;
    polyPtr->fillGC = None;
    polyPtr->smooth = NULL;
    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 = 0; i < objc; i++) {
	const char *arg = Tcl_GetString(objv[i]);

	if ((arg[0] == '-') && (arg[1] >= 'a') && (arg[1] <= 'z')) {
	    break;
	}
    }
    if (i && PolygonCoords(interp, canvas, itemPtr, i, objv) != TCL_OK) {
	goto error;
    }

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

  error:
    DeletePolygon(canvas, itemPtr, Tk_Display(Tk_CanvasTkwin(canvas)));
    return TCL_ERROR;
}

/*
 *--------------------------------------------------------------
 *
 * PolygonCoords --
 *
 *	This function 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 the interp's result.
 *
 * Side effects:
 *	The coordinates for the given item may be changed.
 *
 *--------------------------------------------------------------
 */

static int
PolygonCoords(
    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 objc,			/* Number of coordinates supplied in objv. */
    Tcl_Obj *const objv[])	/* Array of coordinates: x1, y1, x2, y2, ... */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    int i, numPoints;

    if (objc == 0) {
	/*
	 * Print the coords used to create the polygon. If we auto closed the
	 * polygon then we don't report the last point.
	 */

	Tcl_Obj *subobj, *obj = Tcl_NewObj();

	for (i = 0; i < 2*(polyPtr->numPoints - polyPtr->autoClosed); i++) {
	    subobj = Tcl_NewDoubleObj(polyPtr->coordPtr[i]);
	    Tcl_ListObjAppendElement(interp, obj, subobj);
	}
	Tcl_SetObjResult(interp, obj);
	return TCL_OK;
    }
    if (objc == 1) {
	if (Tcl_ListObjGetElements(interp, objv[0], &objc,
		(Tcl_Obj ***) &objv) != TCL_OK) {
	    return TCL_ERROR;
	}
    }
    if (objc & 1) {
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"wrong # coordinates: expected an even number, got %d",
		objc));
	return TCL_ERROR;
    }

    numPoints = objc/2;
    if (polyPtr->pointsAllocated <= numPoints) {
	if (polyPtr->coordPtr != NULL) {
	    ckfree((char *) polyPtr->coordPtr);
	}

	/*
	 * One extra point gets allocated here, because we always add
	 * another point to close the polygon.
	 */

	polyPtr->coordPtr = (double *)
		ckalloc(sizeof(double) * (unsigned)(objc+2));
	polyPtr->pointsAllocated = numPoints+1;
    }
    for (i = objc-1; i >= 0; i--) {
	if (Tk_CanvasGetCoordFromObj(interp, canvas, objv[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 (objc>2 && ((polyPtr->coordPtr[objc-2] != polyPtr->coordPtr[0])
	    || (polyPtr->coordPtr[objc-1] != polyPtr->coordPtr[1]))) {
	polyPtr->autoClosed = 1;
	polyPtr->numPoints++;
	polyPtr->coordPtr[objc] = polyPtr->coordPtr[0];
	polyPtr->coordPtr[objc+1] = polyPtr->coordPtr[1];
    }

    ComputePolygonBbox(canvas, polyPtr);
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * ConfigurePolygon --
 *
 *	This function 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 the interp's result.
 *
 * Side effects:
 *	Configuration information, such as colors and stipple patterns, may be
 *	set for itemPtr.
 *
 *--------------------------------------------------------------
 */

static int
ConfigurePolygon(
    Tcl_Interp *interp,		/* Interpreter for error reporting. */
    Tk_Canvas canvas,		/* Canvas containing itemPtr. */
    Tk_Item *itemPtr,		/* Polygon item to reconfigure. */
    int objc,			/* Number of elements in objv.  */
    Tcl_Obj *const objv[],	/* 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;
    XColor *color;
    Pixmap stipple;
    Tk_State state;

    tkwin = Tk_CanvasTkwin(canvas);
    if (TCL_OK != Tk_ConfigureWidget(interp, tkwin, configSpecs, objc,
	    (const char **) objv, (char *) polyPtr, flags|TK_CONFIG_OBJS)) {
	return TCL_ERROR;
    }

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

    state = itemPtr->state;

    if (polyPtr->outline.activeWidth > polyPtr->outline.width ||
	    polyPtr->outline.activeDash.number != 0 ||
	    polyPtr->outline.activeColor != NULL ||
	    polyPtr->outline.activeStipple != None ||
	    polyPtr->activeFillColor != NULL ||
	    polyPtr->activeFillStipple != None) {
	itemPtr->redraw_flags |= TK_ITEM_STATE_DEPENDANT;
    } else {
	itemPtr->redraw_flags &= ~TK_ITEM_STATE_DEPENDANT;
    }

    if (state == TK_STATE_NULL) {
	state = Canvas(canvas)->canvas_state;
    }
    if (state == TK_STATE_HIDDEN) {
	ComputePolygonBbox(canvas, polyPtr);
	return TCL_OK;
    }

    mask = Tk_ConfigOutlineGC(&gcValues, canvas, itemPtr, &polyPtr->outline);
    if (mask) {
	gcValues.cap_style = CapRound;
	gcValues.join_style = polyPtr->joinStyle;
	mask |= GCCapStyle|GCJoinStyle;
	newGC = Tk_GetGC(tkwin, mask, &gcValues);
    } else {
	newGC = None;
    }
    if (polyPtr->outline.gc != None) {
	Tk_FreeGC(Tk_Display(tkwin), polyPtr->outline.gc);
    }
    polyPtr->outline.gc = newGC;

    color = polyPtr->fillColor;
    stipple = polyPtr->fillStipple;
    if (Canvas(canvas)->currentItemPtr == itemPtr) {
	if (polyPtr->activeFillColor != NULL) {
	    color = polyPtr->activeFillColor;
	}
	if (polyPtr->activeFillStipple != None) {
	    stipple = polyPtr->activeFillStipple;
	}
    } else if (state == TK_STATE_DISABLED) {
	if (polyPtr->disabledFillColor != NULL) {
	    color = polyPtr->disabledFillColor;
	}
	if (polyPtr->disabledFillStipple != None) {
	    stipple = polyPtr->disabledFillStipple;
	}
    }

    if (color == NULL) {
	newGC = None;
    } else {
	gcValues.foreground = color->pixel;
	mask = GCForeground;
	if (stipple != None) {
	    gcValues.stipple = stipple;
	    gcValues.fill_style = FillStippled;
	    mask |= GCStipple|GCFillStyle;
	}
#ifdef MAC_OSX_TK
	/*
	 * Mac OS X CG drawing needs access to the outline linewidth
	 * even for fills (as linewidth controls antialiasing).
	 */
	gcValues.line_width = polyPtr->outline.gc != None ?
		polyPtr->outline.gc->line_width : 0;
	mask |= GCLineWidth;
#endif
	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 function 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(
    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;

    Tk_DeleteOutline(display, &polyPtr->outline);
    if (polyPtr->coordPtr != NULL) {
	ckfree((char *) polyPtr->coordPtr);
    }
    if (polyPtr->fillColor != NULL) {
	Tk_FreeColor(polyPtr->fillColor);
    }
    if (polyPtr->activeFillColor != NULL) {
	Tk_FreeColor(polyPtr->activeFillColor);
    }
    if (polyPtr->disabledFillColor != NULL) {
	Tk_FreeColor(polyPtr->disabledFillColor);
    }
    if (polyPtr->fillStipple != None) {
	Tk_FreeBitmap(display, polyPtr->fillStipple);
    }
    if (polyPtr->activeFillStipple != None) {
	Tk_FreeBitmap(display, polyPtr->activeFillStipple);
    }
    if (polyPtr->disabledFillStipple != None) {
	Tk_FreeBitmap(display, polyPtr->disabledFillStipple);
    }
    if (polyPtr->fillGC != None) {
	Tk_FreeGC(display, polyPtr->fillGC);
    }
}

/*
 *--------------------------------------------------------------
 *
 * ComputePolygonBbox --
 *
 *	This function 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(
    Tk_Canvas canvas,		/* Canvas that contains item. */
    PolygonItem *polyPtr)	/* Item whose bbox is to be recomputed. */
{
    double *coordPtr;
    int i;
    double width;
    Tk_State state = polyPtr->header.state;
    Tk_TSOffset *tsoffset;

    if (state == TK_STATE_NULL) {
	state = Canvas(canvas)->canvas_state;
    }
    width = polyPtr->outline.width;
    if (polyPtr->coordPtr == NULL || (polyPtr->numPoints < 1)
	    || (state == TK_STATE_HIDDEN)) {
	polyPtr->header.x1 = polyPtr->header.x2 =
		polyPtr->header.y1 = polyPtr->header.y2 = -1;
	return;
    }
    if (Canvas(canvas)->currentItemPtr == (Tk_Item *) polyPtr) {
	if (polyPtr->outline.activeWidth > width) {
	    width = polyPtr->outline.activeWidth;
	}
    } else if (state == TK_STATE_DISABLED) {
	if (polyPtr->outline.disabledWidth > 0.0) {
	    width = polyPtr->outline.disabledWidth;
	}
    }

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

    /*
     * Compute the bounding box of all the points in the polygon, then expand
     * in all directions by the outline'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 = polyPtr->coordPtr+2; i < polyPtr->numPoints-1;
	    i++, coordPtr += 2) {
	TkIncludePoint((Tk_Item *) polyPtr, coordPtr);
    }

    tsoffset = &polyPtr->tsoffset;
    if (tsoffset->flags & TK_OFFSET_INDEX) {
	int index = tsoffset->flags & ~TK_OFFSET_INDEX;

	if (tsoffset->flags == INT_MAX) {
	    index = (polyPtr->numPoints - polyPtr->autoClosed) * 2;
	    if (index < 0) {
		index = 0;
	    }
	}
	index %= (polyPtr->numPoints - polyPtr->autoClosed) * 2;
	if (index < 0) {
	    index += (polyPtr->numPoints - polyPtr->autoClosed) * 2;
	}
 	tsoffset->xoffset = (int) (polyPtr->coordPtr[index] + 0.5);
	tsoffset->yoffset = (int) (polyPtr->coordPtr[index+1] + 0.5);
    } else {
	if (tsoffset->flags & TK_OFFSET_LEFT) {
	    tsoffset->xoffset = polyPtr->header.x1;
	} else if (tsoffset->flags & TK_OFFSET_CENTER) {
	    tsoffset->xoffset = (polyPtr->header.x1 + polyPtr->header.x2)/2;
	} else if (tsoffset->flags & TK_OFFSET_RIGHT) {
	    tsoffset->xoffset = polyPtr->header.x2;
	}
	if (tsoffset->flags & TK_OFFSET_TOP) {
	    tsoffset->yoffset = polyPtr->header.y1;
	} else if (tsoffset->flags & TK_OFFSET_MIDDLE) {
	    tsoffset->yoffset = (polyPtr->header.y1 + polyPtr->header.y2)/2;
	} else if (tsoffset->flags & TK_OFFSET_BOTTOM) {
	    tsoffset->yoffset = polyPtr->header.y2;
	}
    }

    if (polyPtr->outline.gc != None) {
	tsoffset = &polyPtr->outline.tsoffset;
	if (tsoffset) {
	    if (tsoffset->flags & TK_OFFSET_INDEX) {
		int index = tsoffset->flags & ~TK_OFFSET_INDEX;

		if (tsoffset->flags == INT_MAX) {
		    index = (polyPtr->numPoints - 1) * 2;
		}
		index %= (polyPtr->numPoints - 1) * 2;
		if (index < 0) {
		    index += (polyPtr->numPoints - 1) * 2;
		}
		tsoffset->xoffset = (int) (polyPtr->coordPtr[index] + 0.5);
		tsoffset->yoffset = (int) (polyPtr->coordPtr[index+1] + 0.5);
	    } else {
		if (tsoffset->flags & TK_OFFSET_LEFT) {
		    tsoffset->xoffset = polyPtr->header.x1;
		} else if (tsoffset->flags & TK_OFFSET_CENTER) {
		    tsoffset->xoffset =
			    (polyPtr->header.x1 + polyPtr->header.x2) / 2;
		} else if (tsoffset->flags & TK_OFFSET_RIGHT) {
		    tsoffset->xoffset = polyPtr->header.x2;
		}
		if (tsoffset->flags & TK_OFFSET_TOP) {
		    tsoffset->yoffset = polyPtr->header.y1;
		} else if (tsoffset->flags & TK_OFFSET_MIDDLE) {
		    tsoffset->yoffset =
			    (polyPtr->header.y1 + polyPtr->header.y2) / 2;
		} else if (tsoffset->flags & TK_OFFSET_BOTTOM) {
		    tsoffset->yoffset = polyPtr->header.y2;
		}
	    }
	}

	i = (int) ((width+1.5) / 2.0);
	polyPtr->header.x1 -= i;
	polyPtr->header.x2 += i;
	polyPtr->header.y1 -= i;
	polyPtr->header.y2 += i;

	/*
	 * 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 (polyPtr->joinStyle == JoinMiter) {
	    double miter[4];
	    int j;

	    coordPtr = polyPtr->coordPtr;
	    if (polyPtr->numPoints > 3) {
		if (TkGetMiterPoints(coordPtr+2*(polyPtr->numPoints-2),
			coordPtr, coordPtr+2, width, miter, miter+2)) {
		    for (j = 0; j < 4; j += 2) {
			TkIncludePoint((Tk_Item *) polyPtr, miter+j);
		    }
		}
	    }
	    for (i = polyPtr->numPoints ; i >= 3; i--, coordPtr += 2) {
		if (TkGetMiterPoints(coordPtr, coordPtr+2, coordPtr+4, width,
			miter, miter+2)) {
		    for (j = 0; j < 4; j += 2) {
			TkIncludePoint((Tk_Item *) polyPtr, miter+j);
		    }
		}
	    }
	}
    }

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

    polyPtr->header.x1 -= 1;
    polyPtr->header.x2 += 1;
    polyPtr->header.y1 -= 1;
    polyPtr->header.y2 += 1;
}

/*
 *--------------------------------------------------------------
 *
 * TkFillPolygon --
 *
 *	This function 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(
    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 && numPoints > 3) {
	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 function 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(
    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, int y, int width, int height)
				/* Describes region of canvas that must be
				 * redisplayed (not used). */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    Tk_State state = itemPtr->state;
    Pixmap stipple = polyPtr->fillStipple;
    double linewidth = polyPtr->outline.width;

    if (((polyPtr->fillGC == None) && (polyPtr->outline.gc == None)) ||
	    (polyPtr->numPoints < 1) ||
	    (polyPtr->numPoints < 3 && polyPtr->outline.gc == None)) {
	return;
    }

    if (state == TK_STATE_NULL) {
	state = Canvas(canvas)->canvas_state;
    }
    if (Canvas(canvas)->currentItemPtr == itemPtr) {
	if (polyPtr->outline.activeWidth > linewidth) {
	    linewidth = polyPtr->outline.activeWidth;
	}
	if (polyPtr->activeFillStipple != None) {
	    stipple = polyPtr->activeFillStipple;
	}
    } else if (state == TK_STATE_DISABLED) {
	if (polyPtr->outline.disabledWidth > 0.0) {
	    linewidth = polyPtr->outline.disabledWidth;
	}
	if (polyPtr->disabledFillStipple != None) {
	    stipple = polyPtr->disabledFillStipple;
	}
    }

    /*
     * 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 ((stipple != None) && (polyPtr->fillGC != None)) {
	Tk_TSOffset *tsoffset = &polyPtr->tsoffset;
	int w = 0, h = 0;
	int flags = tsoffset->flags;

	if (!(flags & TK_OFFSET_INDEX)
		&& (flags & (TK_OFFSET_CENTER|TK_OFFSET_MIDDLE))) {
	    Tk_SizeOfBitmap(display, stipple, &w, &h);
	    if (flags & TK_OFFSET_CENTER) {
		w /= 2;
	    } else {
		w = 0;
	    }
	    if (flags & TK_OFFSET_MIDDLE) {
		h /= 2;
	    } else {
		h = 0;
	    }
	}
	tsoffset->xoffset -= w;
	tsoffset->yoffset -= h;
	Tk_CanvasSetOffset(canvas, polyPtr->fillGC, tsoffset);
	tsoffset->xoffset += w;
	tsoffset->yoffset += h;
    }
    Tk_ChangeOutlineGC(canvas, itemPtr, &polyPtr->outline);

    if (polyPtr->numPoints < 3) {
	short x, y;
	int intLineWidth = (int) (linewidth + 0.5);

	if (intLineWidth < 1) {
	    intLineWidth = 1;
	}
	Tk_CanvasDrawableCoords(canvas, polyPtr->coordPtr[0],
		polyPtr->coordPtr[1], &x, &y);
	XFillArc(display, drawable, polyPtr->outline.gc,
		x - intLineWidth/2, y - intLineWidth/2,
		(unsigned) intLineWidth+1, (unsigned) intLineWidth+1,
		0, 64*360);
    } else if (!polyPtr->smooth || polyPtr->numPoints < 4) {
	TkFillPolygon(canvas, polyPtr->coordPtr, polyPtr->numPoints,
		    display, drawable, polyPtr->fillGC, polyPtr->outline.gc);
    } 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 = polyPtr->smooth->coordProc(canvas, NULL,
		polyPtr->numPoints, polyPtr->splineSteps, NULL, NULL);
	if (numPoints <= MAX_STATIC_POINTS) {
	    pointPtr = staticPoints;
	} else {
	    pointPtr = (XPoint *)
		    ckalloc((unsigned) numPoints * sizeof(XPoint));
	}
	numPoints = polyPtr->smooth->coordProc(canvas, polyPtr->coordPtr,
		polyPtr->numPoints, polyPtr->splineSteps, pointPtr, NULL);
	if (polyPtr->fillGC != None) {
	    XFillPolygon(display, drawable, polyPtr->fillGC, pointPtr,
		    numPoints, Complex, CoordModeOrigin);
	}
	if (polyPtr->outline.gc != None) {
	    XDrawLines(display, drawable, polyPtr->outline.gc, pointPtr,
		    numPoints, CoordModeOrigin);
	}
	if (pointPtr != staticPoints) {
	    ckfree((char *) pointPtr);
	}
    }
    Tk_ResetOutlineGC(canvas, itemPtr, &polyPtr->outline);
    if ((stipple != None) && (polyPtr->fillGC != None)) {
	XSetTSOrigin(display, polyPtr->fillGC, 0, 0);
    }
}

/*
 *--------------------------------------------------------------
 *
 * PolygonInsert --
 *
 *	Insert coords into a polugon item at a given index.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The coords in the given item is modified.
 *
 *--------------------------------------------------------------
 */

static void
PolygonInsert(
    Tk_Canvas canvas,		/* Canvas containing text item. */
    Tk_Item *itemPtr,		/* Line item to be modified. */
    int beforeThis,		/* Index before which new coordinates are to
				 * be inserted. */
    Tcl_Obj *obj)		/* New coordinates to be inserted. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    int length, objc, i;
    Tcl_Obj **objv;
    double *newCoordPtr;
    Tk_State state = itemPtr->state;

    if (state == TK_STATE_NULL) {
	state = Canvas(canvas)->canvas_state;
    }

    if (!obj || (Tcl_ListObjGetElements(NULL, obj, &objc, &objv) != TCL_OK)
	    || !objc || objc&1) {
	return;
    }
    length = 2*(polyPtr->numPoints - polyPtr->autoClosed);
    while (beforeThis > length) {
	beforeThis -= length;
    }
    while (beforeThis < 0) {
	beforeThis += length;
    }
    newCoordPtr = (double *)
	    ckalloc(sizeof(double) * (unsigned)(length + 2 + objc));
    for (i=0; i<beforeThis; i++) {
	newCoordPtr[i] = polyPtr->coordPtr[i];
    }
    for (i=0; i<objc; i++) {
	if (Tcl_GetDoubleFromObj(NULL, objv[i],
		&newCoordPtr[i+beforeThis]) != TCL_OK){
	    ckfree((char *) newCoordPtr);
	    return;
	}
    }

    for (i=beforeThis; i<length; i++) {
	newCoordPtr[i+objc] = polyPtr->coordPtr[i];
    }
    if (polyPtr->coordPtr) {
	ckfree((char *) polyPtr->coordPtr);
    }
    length += objc;
    polyPtr->coordPtr = newCoordPtr;
    polyPtr->numPoints = (length/2) + polyPtr->autoClosed;

    /*
     * Close the polygon if it isn't already closed, or remove autoclosing if
     * the user's coordinates are now closed.
     */

    if (polyPtr->autoClosed) {
	if ((newCoordPtr[length-2] == newCoordPtr[0])
		&& (newCoordPtr[length-1] == newCoordPtr[1])) {
	    polyPtr->autoClosed = 0;
	    polyPtr->numPoints--;
	}
    } else {
	if ((newCoordPtr[length-2] != newCoordPtr[0])
		|| (newCoordPtr[length-1] != newCoordPtr[1])) {
	    polyPtr->autoClosed = 1;
	    polyPtr->numPoints++;
	}
    }

    newCoordPtr[length] = newCoordPtr[0];
    newCoordPtr[length+1] = newCoordPtr[1];
    if ((length-objc > 3) && (state != TK_STATE_HIDDEN)) {
	/*
	 * This is some optimizing code that will result that only the part of
	 * the polygon that changed (and the objects that are overlapping with
	 * that part) need to be redrawn. A special flag is set that instructs
	 * the general canvas code not to redraw the whole object. If this
	 * flag is not set, the canvas will do the redrawing, otherwise I have
	 * to do it here.
	 */

    	double width;
	int j;

	itemPtr->redraw_flags |= TK_ITEM_DONT_REDRAW;

	/*
	 * The header elements that normally are used for the bounding box,
	 * are now used to calculate the bounding box for only the part that
	 * has to be redrawn. That doesn't matter, because afterwards the
	 * bounding box has to be re-calculated anyway.
	 */

	itemPtr->x1 = itemPtr->x2 = (int) polyPtr->coordPtr[beforeThis];
	itemPtr->y1 = itemPtr->y2 = (int) polyPtr->coordPtr[beforeThis+1];
	beforeThis -= 2;
	objc += 4;
	if (polyPtr->smooth) {
	    beforeThis -= 2;
	    objc += 4;
	}

	/*
	 * Be careful; beforeThis could now be negative
	 */

	for (i=beforeThis; i<beforeThis+objc; i+=2) {
	    j = i;
	    if (j < 0) {
		j += length;
	    } else if (j >= length) {
		j -= length;
	    }
	    TkIncludePoint(itemPtr, polyPtr->coordPtr+j);
	}
	width = polyPtr->outline.width;
	if (Canvas(canvas)->currentItemPtr == itemPtr) {
	    if (polyPtr->outline.activeWidth > width) {
		width = polyPtr->outline.activeWidth;
	    }
	} else if (state == TK_STATE_DISABLED) {
	    if (polyPtr->outline.disabledWidth > 0.0) {
		width = polyPtr->outline.disabledWidth;
	    }
	}
	itemPtr->x1 -= (int) width;
	itemPtr->y1 -= (int) width;
	itemPtr->x2 += (int) width;
	itemPtr->y2 += (int) width;
	Tk_CanvasEventuallyRedraw(canvas,
		itemPtr->x1, itemPtr->y1, itemPtr->x2, itemPtr->y2);
    }

    ComputePolygonBbox(canvas, polyPtr);
}

/*
 *--------------------------------------------------------------
 *
 * PolygonDeleteCoords --
 *
 *	Delete one or more coordinates from a polygon item.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Characters between "first" and "last", inclusive, get deleted from
 *	itemPtr.
 *
 *--------------------------------------------------------------
 */

static void
PolygonDeleteCoords(
    Tk_Canvas canvas,		/* Canvas containing itemPtr. */
    Tk_Item *itemPtr,		/* Item in which to delete characters. */
    int first,			/* Index of first character to delete. */
    int last)			/* Index of last character to delete. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    int count, i;
    int length = 2*(polyPtr->numPoints - polyPtr->autoClosed);

    while (first >= length) {
	first -= length;
    }
    while (first < 0) {
	first += length;
    }
    while (last >= length) {
	last -= length;
    }
    while (last < 0) {
	last += length;
    }

    first &= -2;
    last &= -2;

    count = last + 2 - first;
    if (count <= 0) {
	count += length;
    }

    if (count >= length) {
	polyPtr->numPoints = 0;
	if (polyPtr->coordPtr != NULL) {
	    ckfree((char *) polyPtr->coordPtr);
	}
	ComputePolygonBbox(canvas, polyPtr);
	return;
    }

    if (last >= first) {
	for (i=last+2; i<length; i++) {
	    polyPtr->coordPtr[i-count] = polyPtr->coordPtr[i];
	}
    } else {
	for (i=last; i<=first; i++) {
	    polyPtr->coordPtr[i-last] = polyPtr->coordPtr[i];
	}
    }
    polyPtr->coordPtr[length-count] = polyPtr->coordPtr[0];
    polyPtr->coordPtr[length-count+1] = polyPtr->coordPtr[1];
    polyPtr->numPoints -= count/2;
    ComputePolygonBbox(canvas, polyPtr);
}

/*
 *--------------------------------------------------------------
 *
 * 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(
    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, *polyPoints;
    double staticSpace[2*MAX_STATIC_POINTS];
    double poly[10];
    double radius;
    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. */
    double width;
    Tk_State state = itemPtr->state;

    bestDist = 1.0e36;

    if (state == TK_STATE_NULL) {
	state = Canvas(canvas)->canvas_state;
    }
    width = polyPtr->outline.width;
    if (Canvas(canvas)->currentItemPtr == itemPtr) {
	if (polyPtr->outline.activeWidth > width) {
	    width = polyPtr->outline.activeWidth;
	}
    } else if (state == TK_STATE_DISABLED) {
	if (polyPtr->outline.disabledWidth > 0.0) {
	    width = polyPtr->outline.disabledWidth;
	}
    }
    radius = width/2.0;

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

    if ((polyPtr->smooth) && (polyPtr->numPoints > 2)) {
	numPoints = polyPtr->smooth->coordProc(canvas, NULL,
		polyPtr->numPoints, polyPtr->splineSteps, NULL, NULL);
	if (numPoints <= MAX_STATIC_POINTS) {
	    polyPoints = staticSpace;
	} else {
	    polyPoints = (double *)
		    ckalloc((unsigned) 2*numPoints*sizeof(double));
	}
	numPoints = polyPtr->smooth->coordProc(canvas, polyPtr->coordPtr,
		polyPtr->numPoints, polyPtr->splineSteps, NULL, polyPoints);
    } else {
	numPoints = polyPtr->numPoints;
	polyPoints = polyPtr->coordPtr;
    }

    bestDist = TkPolygonToPoint(polyPoints, numPoints, pointPtr);
    if (bestDist <= 0.0) {
	goto donepoint;
    }
    if ((polyPtr->outline.gc != None) && (polyPtr->joinStyle == JoinRound)) {
	dist = bestDist - radius;
	if (dist <= 0.0) {
	    bestDist = 0.0;
	    goto donepoint;
	} else {
	    bestDist = dist;
	}
    }

    if ((polyPtr->outline.gc == None) || (width <= 1)) {
	goto donepoint;
    }

    /*
     * 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 = polyPoints; count >= 2;
	    count--, coordPtr += 2) {
	/*
	 * If rounding is done around the first point then compute the
	 * distance between the point and the point.
	 */

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

  donepoint:
    if (polyPoints != staticSpace && polyPoints != polyPtr->coordPtr) {
	ckfree((char *) polyPoints);
    }
    return bestDist;
}

/*
 *--------------------------------------------------------------
 *
 * PolygonToArea --
 *
 *	This function 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(
    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;
    double staticSpace[2*MAX_STATIC_POINTS];
    double *polyPoints, poly[10];
    double radius;
    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. */
    int inside;			/* Tentative guess about what to return, based
				 * on all points seen so far: one means
				 * everything seen so far was inside the area;
				 * -1 means everything was outside the area. 0
				 * means overlap has been found. */
    double width;
    Tk_State state = itemPtr->state;

    if (state == TK_STATE_NULL) {
	state = Canvas(canvas)->canvas_state;
    }

    width = polyPtr->outline.width;
    if (Canvas(canvas)->currentItemPtr == itemPtr) {
	if (polyPtr->outline.activeWidth > width) {
	    width = polyPtr->outline.activeWidth;
	}
    } else if (state == TK_STATE_DISABLED) {
	if (polyPtr->outline.disabledWidth > 0.0) {
	    width = polyPtr->outline.disabledWidth;
	}
    }

    radius = width/2.0;
    inside = -1;

    if ((state == TK_STATE_HIDDEN) || polyPtr->numPoints < 2) {
	return -1;
    } else if (polyPtr->numPoints < 3) {
	double oval[4];

	oval[0] = polyPtr->coordPtr[0]-radius;
	oval[1] = polyPtr->coordPtr[1]-radius;
	oval[2] = polyPtr->coordPtr[0]+radius;
	oval[3] = polyPtr->coordPtr[1]+radius;
	return TkOvalToArea(oval, rectPtr);
    }

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

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

    /*
     * Simple test to see if we are in the polygon. Polygons are different
     * from othe canvas items in that they register points being inside even
     * if it isn't filled.
     */

    inside = TkPolygonToArea(polyPoints, numPoints, rectPtr);
    if (inside == 0) {
	goto donearea;
    }

    if (polyPtr->outline.gc == None) {
	goto donearea;
    }

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

    changedMiterToBevel = 0;
    for (count = numPoints, coordPtr = polyPoints; count >= 2;
	    count--, coordPtr += 2) {
	/*
	 * If rounding is done around the first point of the edge then test a
	 * circular region around the point with the area.
	 */

	if (polyPtr->joinStyle == JoinRound) {
	    poly[0] = coordPtr[0] - radius;
	    poly[1] = coordPtr[1] - radius;
	    poly[2] = coordPtr[0] + radius;
	    poly[3] = coordPtr[1] + radius;
	    if (TkOvalToArea(poly, rectPtr) != inside) {
		inside = 0;
		goto donearea;
	    }
	}

	/*
	 * 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, width, 0, poly, poly+2);
	} else if ((polyPtr->joinStyle == JoinMiter) && !changedMiterToBevel) {
	    poly[0] = poly[6];
	    poly[1] = poly[7];
	    poly[2] = poly[4];
	    poly[3] = poly[5];
	} else {
	    TkGetButtPoints(coordPtr+2, coordPtr, width, 0, poly, poly+2);

	    /*
	     * If the last joint was beveled, then also check 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 beveled joint.
	     */

	    if ((polyPtr->joinStyle == JoinBevel) || changedMiterToBevel) {
		poly[8] = poly[0];
		poly[9] = poly[1];
		if (TkPolygonToArea(poly, 5, rectPtr) != inside) {
		    inside = 0;
		    goto donearea;
		}
		changedMiterToBevel = 0;
	    }
	}
	if (count == 2) {
	    TkGetButtPoints(coordPtr, coordPtr+2, width, 0, poly+4, poly+6);
	} else if (polyPtr->joinStyle == JoinMiter) {
	    if (TkGetMiterPoints(coordPtr, coordPtr+2, coordPtr+4, width,
		    poly+4, poly+6) == 0) {
		changedMiterToBevel = 1;
		TkGetButtPoints(coordPtr, coordPtr+2, width,0, poly+4, poly+6);
	    }
	} else {
	    TkGetButtPoints(coordPtr, coordPtr+2, width, 0, poly+4, poly+6);
	}
	poly[8] = poly[0];
	poly[9] = poly[1];
	if (TkPolygonToArea(poly, 5, rectPtr) != inside) {
	    inside = 0;
	    goto donearea;
	}
    }

  donearea:
    if ((polyPoints != staticSpace) && (polyPoints != polyPtr->coordPtr)) {
	ckfree((char *) polyPoints);
    }
    return inside;
}

/*
 *--------------------------------------------------------------
 *
 * ScalePolygon --
 *
 *	This function 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(
    Tk_Canvas canvas,		/* Canvas containing polygon. */
    Tk_Item *itemPtr,		/* Polygon to be scaled. */
    double originX, double 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);
}

/*
 *--------------------------------------------------------------
 *
 * GetPolygonIndex --
 *
 *	Parse an index into a polygon item and return either its value or an
 *	error.
 *
 * Results:
 *	A standard Tcl result. If all went well, then *indexPtr is filled in
 *	with the index (into itemPtr) corresponding to string. Otherwise an
 *	error message is left in interp->result.
 *
 * Side effects:
 *	None.
 *
 *--------------------------------------------------------------
 */

static int
GetPolygonIndex(
    Tcl_Interp *interp,		/* Used for error reporting. */
    Tk_Canvas canvas,		/* Canvas containing item. */
    Tk_Item *itemPtr,		/* Item for which the index is being
				 * specified. */
    Tcl_Obj *obj,		/* Specification of a particular coord in
				 * itemPtr's line. */
    int *indexPtr)		/* Where to store converted index. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    int length;
    const char *string = Tcl_GetStringFromObj(obj, &length);

    if (string[0] == 'e') {
	if (strncmp(string, "end", (unsigned)length) != 0) {
	    goto badIndex;
	}
	*indexPtr = 2*(polyPtr->numPoints - polyPtr->autoClosed);
    } else if (string[0] == '@') {
	int i;
	double x, y, bestDist, dist, *coordPtr;
	char *end;
	const char *p;

	p = string+1;
	x = strtod(p, &end);
	if ((end == p) || (*end != ',')) {
	    goto badIndex;
	}
	p = end+1;
	y = strtod(p, &end);
	if ((end == p) || (*end != 0)) {
	    goto badIndex;
	}
	bestDist = 1.0e36;
	coordPtr = polyPtr->coordPtr;
	*indexPtr = 0;
	for (i=0; i<polyPtr->numPoints-1; i++) {
	    dist = hypot(coordPtr[0] - x, coordPtr[1] - y);
	    if (dist < bestDist) {
		bestDist = dist;
		*indexPtr = 2*i;
	    }
	    coordPtr += 2;
	}
    } else {
	int count = 2*(polyPtr->numPoints - polyPtr->autoClosed);

	if (Tcl_GetIntFromObj(interp, obj, indexPtr) != TCL_OK) {
	    goto badIndex;
	}
	*indexPtr &= -2; /* if odd, make it even */
	if (!count) {
	    *indexPtr = 0;
	} else if (*indexPtr > 0) {
	    *indexPtr = ((*indexPtr - 2) % count) + 2;
	} else {
	    *indexPtr = -((-(*indexPtr)) % count);
	}
    }
    return TCL_OK;

    /*
     * Some of the paths here leave messages in interp->result, so we have to
     * clear it out before storing our own message.
     */

  badIndex:
    Tcl_SetObjResult(interp, Tcl_ObjPrintf("bad index \"%s\"", string));
    return TCL_ERROR;
}

/*
 *--------------------------------------------------------------
 *
 * TranslatePolygon --
 *
 *	This function 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(
    Tk_Canvas canvas,		/* Canvas containing item. */
    Tk_Item *itemPtr,		/* Item that is being moved. */
    double deltaX, double 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 function 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 the interp's
 *	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(
    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. */
{
    PolygonItem *polyPtr = (PolygonItem *) itemPtr;
    const char *style;
    XColor *color;
    XColor *fillColor;
    Pixmap stipple;
    Pixmap fillStipple;
    Tk_State state = itemPtr->state;
    double width;

    if (polyPtr->numPoints < 2 || polyPtr->coordPtr == NULL) {
	return TCL_OK;
    }

    if (state == TK_STATE_NULL) {
	state = Canvas(canvas)->canvas_state;
    }
    width = polyPtr->outline.width;
    color = polyPtr->outline.color;
    stipple = polyPtr->fillStipple;
    fillColor = polyPtr->fillColor;
    fillStipple = polyPtr->fillStipple;
    if (Canvas(canvas)->currentItemPtr == itemPtr) {
	if (polyPtr->outline.activeWidth > width) {
	    width = polyPtr->outline.activeWidth;
	}
	if (polyPtr->outline.activeColor != NULL) {
	    color = polyPtr->outline.activeColor;
	}
	if (polyPtr->outline.activeStipple != None) {
	    stipple = polyPtr->outline.activeStipple;
	}
	if (polyPtr->activeFillColor != NULL) {
	    fillColor = polyPtr->activeFillColor;
	}
	if (polyPtr->activeFillStipple != None) {
	    fillStipple = polyPtr->activeFillStipple;
	}
    } else if (state == TK_STATE_DISABLED) {
	if (polyPtr->outline.disabledWidth > 0.0) {
	    width = polyPtr->outline.disabledWidth;
	}
	if (polyPtr->outline.disabledColor != NULL) {
	    color = polyPtr->outline.disabledColor;
	}
	if (polyPtr->outline.disabledStipple != None) {
	    stipple = polyPtr->outline.disabledStipple;
	}
	if (polyPtr->disabledFillColor != NULL) {
	    fillColor = polyPtr->disabledFillColor;
	}
	if (polyPtr->disabledFillStipple != None) {
	    fillStipple = polyPtr->disabledFillStipple;
	}
    }
    if (polyPtr->numPoints == 2) {
	if (color == NULL) {
	    return TCL_OK;
	}

	/*
	 * Create a point by using a small circle. (Printer pixels are too
	 * tiny to be used directly...)
	 */

	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"matrix currentmatrix\n"	/* save state */
		"%.15g %.15g translate "	/* go to drawing location */
		"%.15g %.15g scale "		/* scale the drawing */
		"1 0 moveto "			/* correct for origin */
		"0 0 1 0 360 arc\n"		/* make the circle */
		"setmatrix\n",			/* restore state */
		polyPtr->coordPtr[0],
		Tk_CanvasPsY(canvas, polyPtr->coordPtr[1]),
		width/2.0, width/2.0));

	/*
	 * Color it in.
	 */

	if (Tk_CanvasPsColor(interp, canvas, color) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (stipple != None) {
	    Tcl_AppendResult(interp, "clip ", NULL);
	    if (Tk_CanvasPsStipple(interp, canvas, stipple) != TCL_OK) {
		return TCL_ERROR;
	    }
	} else {
	    Tcl_AppendResult(interp, "fill\n", NULL);
	}
	return TCL_OK;
    }

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

    if (fillColor != NULL && polyPtr->numPoints > 3) {
	if (!polyPtr->smooth || !polyPtr->smooth->postscriptProc) {
	    Tk_CanvasPsPath(interp, canvas, polyPtr->coordPtr,
		    polyPtr->numPoints);
	} else {
	    polyPtr->smooth->postscriptProc(interp, canvas, polyPtr->coordPtr,
		    polyPtr->numPoints, polyPtr->splineSteps);
	}
	if (Tk_CanvasPsColor(interp, canvas, fillColor) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (fillStipple != None) {
	    Tcl_AppendResult(interp, "eoclip ", NULL);
	    if (Tk_CanvasPsStipple(interp, canvas, fillStipple) != TCL_OK) {
		return TCL_ERROR;
	    }
	    if (color != NULL) {
		Tcl_AppendResult(interp, "grestore gsave\n", NULL);
	    }
	} else {
	    Tcl_AppendResult(interp, "eofill\n", NULL);
	}
    }

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

    if (color != NULL) {
	if (!polyPtr->smooth || !polyPtr->smooth->postscriptProc) {
	    Tk_CanvasPsPath(interp, canvas, polyPtr->coordPtr,
		    polyPtr->numPoints);
	} else {
	    polyPtr->smooth->postscriptProc(interp, canvas, polyPtr->coordPtr,
		    polyPtr->numPoints, polyPtr->splineSteps);
	}

	if (polyPtr->joinStyle == JoinRound) {
	    style = "1";
	} else if (polyPtr->joinStyle == JoinBevel) {
	    style = "2";
	} else {
	    style = "0";
	}
	Tcl_AppendResult(interp, style, " setlinejoin 1 setlinecap\n", NULL);
	if (Tk_CanvasPsOutline(canvas, itemPtr, &polyPtr->outline) != TCL_OK){
	    return TCL_ERROR;
	}
    }
    return TCL_OK;
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */