Initial revision

1 files changed, 1716 insertions, 0 deletions

diff --git a/generic/tkCanvArc.c b/generic/tkCanvArc.c
new file mode 100644
index 0000000..26b62e7
--- /dev/null
+++ b/generic/tkCanvArc.c
@@ -0,0 +1,1716 @@
+/* 
+ * tkCanvArc.c --
+ *
+ *	This file implements arc items for canvas widgets.
+ *
+ * Copyright (c) 1992-1994 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.
+ *
+ * SCCS: @(#) tkCanvArc.c 1.34 97/04/25 16:50:56
+ */
+
+#include <stdio.h>
+#include "tkPort.h"
+#include "tkInt.h"
+
+/*
+ * The structure below defines the record for each arc item.
+ */
+
+typedef struct ArcItem  {
+    Tk_Item header;		/* Generic stuff that's the same for all
+				 * types.  MUST BE FIRST IN STRUCTURE. */
+    double bbox[4];		/* Coordinates (x1, y1, x2, y2) of bounding
+				 * box for oval of which arc is a piece. */
+    double start;		/* Angle at which arc begins, in degrees
+				 * between 0 and 360. */
+    double extent;		/* Extent of arc (angular distance from
+				 * start to end of arc) in degrees between
+				 * -360 and 360. */
+    double *outlinePtr;		/* Points to (x,y) coordinates for points
+				 * that define one or two closed polygons
+				 * representing the portion of the outline
+				 * that isn't part of the arc (the V-shape
+				 * for a pie slice or a line-like segment
+				 * for a chord).  Malloc'ed. */
+    int numOutlinePoints;	/* Number of points at outlinePtr.  Zero
+				 * means no space allocated. */
+    int width;			/* Width of outline (in pixels). */
+    XColor *outlineColor;	/* Color for outline.  NULL means don't
+				 * draw outline. */
+    XColor *fillColor;		/* Color for filling arc (used for drawing
+				 * outline too when style is "arc").  NULL
+				 * means don't fill arc. */
+    Pixmap fillStipple;		/* Stipple bitmap for filling item. */
+    Pixmap outlineStipple;	/* Stipple bitmap for outline. */
+    Tk_Uid style;		/* How to draw arc: arc, chord, or pieslice. */
+    GC outlineGC;		/* Graphics context for outline. */
+    GC fillGC;			/* Graphics context for filling item. */
+    double center1[2];		/* Coordinates of center of arc outline at
+				 * start (see ComputeArcOutline). */
+    double center2[2];		/* Coordinates of center of arc outline at
+				 * start+extent (see ComputeArcOutline). */
+} ArcItem;
+
+/*
+ * The definitions below define the sizes of the polygons used to
+ * display outline information for various styles of arcs:
+ */
+
+#define CHORD_OUTLINE_PTS	7
+#define PIE_OUTLINE1_PTS	6
+#define PIE_OUTLINE2_PTS	7
+
+/*
+ * Information used for parsing configuration specs:
+ */
+
+static Tk_CustomOption tagsOption = {Tk_CanvasTagsParseProc,
+    Tk_CanvasTagsPrintProc, (ClientData) NULL
+};
+
+static Tk_ConfigSpec configSpecs[] = {
+    {TK_CONFIG_DOUBLE, "-extent", (char *) NULL, (char *) NULL,
+	"90", Tk_Offset(ArcItem, extent), TK_CONFIG_DONT_SET_DEFAULT},
+    {TK_CONFIG_COLOR, "-fill", (char *) NULL, (char *) NULL,
+	(char *) NULL, Tk_Offset(ArcItem, fillColor), TK_CONFIG_NULL_OK},
+    {TK_CONFIG_COLOR, "-outline", (char *) NULL, (char *) NULL,
+	"black", Tk_Offset(ArcItem, outlineColor), TK_CONFIG_NULL_OK},
+    {TK_CONFIG_BITMAP, "-outlinestipple", (char *) NULL, (char *) NULL,
+	(char *) NULL, Tk_Offset(ArcItem, outlineStipple), TK_CONFIG_NULL_OK},
+    {TK_CONFIG_DOUBLE, "-start", (char *) NULL, (char *) NULL,
+	"0", Tk_Offset(ArcItem, start), TK_CONFIG_DONT_SET_DEFAULT},
+    {TK_CONFIG_BITMAP, "-stipple", (char *) NULL, (char *) NULL,
+	(char *) NULL, Tk_Offset(ArcItem, fillStipple), TK_CONFIG_NULL_OK},
+    {TK_CONFIG_UID, "-style", (char *) NULL, (char *) NULL,
+	"pieslice", Tk_Offset(ArcItem, style), TK_CONFIG_DONT_SET_DEFAULT},
+    {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(ArcItem, 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		ComputeArcBbox _ANSI_ARGS_((Tk_Canvas canvas,
+			    ArcItem *arcPtr));
+static int		ConfigureArc _ANSI_ARGS_((Tcl_Interp *interp,
+			    Tk_Canvas canvas, Tk_Item *itemPtr, int argc,
+			    char **argv, int flags));
+static int		CreateArc _ANSI_ARGS_((Tcl_Interp *interp,
+			    Tk_Canvas canvas, struct Tk_Item *itemPtr,
+			    int argc, char **argv));
+static void		DeleteArc _ANSI_ARGS_((Tk_Canvas canvas,
+			    Tk_Item *itemPtr, Display *display));
+static void		DisplayArc _ANSI_ARGS_((Tk_Canvas canvas,
+			    Tk_Item *itemPtr, Display *display, Drawable dst,
+			    int x, int y, int width, int height));
+static int		ArcCoords _ANSI_ARGS_((Tcl_Interp *interp,
+			    Tk_Canvas canvas, Tk_Item *itemPtr, int argc,
+			    char **argv));
+static int		ArcToArea _ANSI_ARGS_((Tk_Canvas canvas,
+			    Tk_Item *itemPtr, double *rectPtr));
+static double		ArcToPoint _ANSI_ARGS_((Tk_Canvas canvas,
+			    Tk_Item *itemPtr, double *coordPtr));
+static int		ArcToPostscript _ANSI_ARGS_((Tcl_Interp *interp,
+			    Tk_Canvas canvas, Tk_Item *itemPtr, int prepass));
+static void		ScaleArc _ANSI_ARGS_((Tk_Canvas canvas,
+			    Tk_Item *itemPtr, double originX, double originY,
+			    double scaleX, double scaleY));
+static void		TranslateArc _ANSI_ARGS_((Tk_Canvas canvas,
+			    Tk_Item *itemPtr, double deltaX, double deltaY));
+static int		AngleInRange _ANSI_ARGS_((double x, double y,
+			    double start, double extent));
+static void		ComputeArcOutline _ANSI_ARGS_((ArcItem *arcPtr));
+static int		HorizLineToArc _ANSI_ARGS_((double x1, double x2,
+			    double y, double rx, double ry,
+			    double start, double extent));
+static int		VertLineToArc _ANSI_ARGS_((double x, double y1,
+			    double y2, double rx, double ry,
+			    double start, double extent));
+
+/*
+ * The structures below defines the arc item types by means of procedures
+ * that can be invoked by generic item code.
+ */
+
+Tk_ItemType tkArcType = {
+    "arc",				/* name */
+    sizeof(ArcItem),			/* itemSize */
+    CreateArc,				/* createProc */
+    configSpecs,			/* configSpecs */
+    ConfigureArc,			/* configureProc */
+    ArcCoords,				/* coordProc */
+    DeleteArc,				/* deleteProc */
+    DisplayArc,				/* displayProc */
+    0,					/* alwaysRedraw */
+    ArcToPoint,				/* pointProc */
+    ArcToArea,				/* areaProc */
+    ArcToPostscript,			/* postscriptProc */
+    ScaleArc,				/* scaleProc */
+    TranslateArc,			/* 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 */
+};
+
+#ifndef PI
+#    define PI 3.14159265358979323846
+#endif
+
+/*
+ * The uid's below comprise the legal values for the "-style"
+ * option for arcs.
+ */
+
+static Tk_Uid arcUid =  NULL;
+static Tk_Uid chordUid =  NULL;
+static Tk_Uid pieSliceUid = NULL;
+
+/*
+ *--------------------------------------------------------------
+ *
+ * CreateArc --
+ *
+ *	This procedure is invoked to create a new arc 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 arc item is created.
+ *
+ *--------------------------------------------------------------
+ */
+
+static int
+CreateArc(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 arc. */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+
+    if (argc < 4) {
+	Tcl_AppendResult(interp, "wrong # args: should be \"",
+		Tk_PathName(Tk_CanvasTkwin(canvas)), " create ",
+		itemPtr->typePtr->name, " x1 y1 x2 y2 ?options?\"",
+		(char *) NULL);
+	return TCL_ERROR;
+    }
+
+    /*
+     * Carry out once-only initialization.
+     */
+
+    if (arcUid == NULL) {
+	arcUid = Tk_GetUid("arc");
+	chordUid = Tk_GetUid("chord");
+	pieSliceUid = Tk_GetUid("pieslice");
+    }
+
+    /*
+     * Carry out initialization that is needed in order to clean
+     * up after errors during the the remainder of this procedure.
+     */
+
+    arcPtr->start = 0;
+    arcPtr->extent = 90;
+    arcPtr->outlinePtr = NULL;
+    arcPtr->numOutlinePoints = 0;
+    arcPtr->width = 1;
+    arcPtr->outlineColor = NULL;
+    arcPtr->fillColor = NULL;
+    arcPtr->fillStipple = None;
+    arcPtr->outlineStipple = None;
+    arcPtr->style = pieSliceUid;
+    arcPtr->outlineGC = None;
+    arcPtr->fillGC = None;
+
+    /*
+     * Process the arguments to fill in the item record.
+     */
+
+    if ((Tk_CanvasGetCoord(interp, canvas, argv[0], &arcPtr->bbox[0]) != TCL_OK)
+	    || (Tk_CanvasGetCoord(interp, canvas, argv[1],
+		&arcPtr->bbox[1]) != TCL_OK)
+	    || (Tk_CanvasGetCoord(interp, canvas, argv[2],
+		    &arcPtr->bbox[2]) != TCL_OK)
+	    || (Tk_CanvasGetCoord(interp, canvas, argv[3],
+		    &arcPtr->bbox[3]) != TCL_OK)) {
+	return TCL_ERROR;
+    }
+
+    if (ConfigureArc(interp, canvas, itemPtr, argc-4, argv+4, 0) != TCL_OK) {
+	DeleteArc(canvas, itemPtr, Tk_Display(Tk_CanvasTkwin(canvas)));
+	return TCL_ERROR;
+    }
+    return TCL_OK;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * ArcCoords --
+ *
+ *	This procedure is invoked to process the "coords" widget
+ *	command on arcs.  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
+ArcCoords(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, ... */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+    char c0[TCL_DOUBLE_SPACE], c1[TCL_DOUBLE_SPACE];
+    char c2[TCL_DOUBLE_SPACE], c3[TCL_DOUBLE_SPACE];
+
+    if (argc == 0) {
+	Tcl_PrintDouble(interp, arcPtr->bbox[0], c0);
+	Tcl_PrintDouble(interp, arcPtr->bbox[1], c1);
+	Tcl_PrintDouble(interp, arcPtr->bbox[2], c2);
+	Tcl_PrintDouble(interp, arcPtr->bbox[3], c3);
+	Tcl_AppendResult(interp, c0, " ", c1, " ", c2, " ", c3,
+		(char *) NULL);
+    } else if (argc == 4) {
+	if ((Tk_CanvasGetCoord(interp, canvas, argv[0],
+		    &arcPtr->bbox[0]) != TCL_OK)
+		|| (Tk_CanvasGetCoord(interp, canvas, argv[1],
+		    &arcPtr->bbox[1]) != TCL_OK)
+		|| (Tk_CanvasGetCoord(interp, canvas, argv[2],
+			&arcPtr->bbox[2]) != TCL_OK)
+		|| (Tk_CanvasGetCoord(interp, canvas, argv[3],
+			&arcPtr->bbox[3]) != TCL_OK)) {
+	    return TCL_ERROR;
+	}
+	ComputeArcBbox(canvas, arcPtr);
+    } else {
+	sprintf(interp->result,
+		"wrong # coordinates: expected 0 or 4, got %d",
+		argc);
+	return TCL_ERROR;
+    }
+    return TCL_OK;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * ConfigureArc --
+ *
+ *	This procedure is invoked to configure various aspects
+ *	of a arc item, such as its outline and fill colors.
+ *
+ * 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
+ConfigureArc(interp, canvas, itemPtr, argc, argv, flags)
+    Tcl_Interp *interp;		/* Used for error reporting. */
+    Tk_Canvas canvas;		/* Canvas containing itemPtr. */
+    Tk_Item *itemPtr;		/* Arc 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. */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+    XGCValues gcValues;
+    GC newGC;
+    unsigned long mask;
+    int i;
+    Tk_Window tkwin;
+
+    tkwin = Tk_CanvasTkwin(canvas);
+    if (Tk_ConfigureWidget(interp, tkwin, configSpecs, argc, argv,
+	    (char *) arcPtr, flags) != TCL_OK) {
+	return TCL_ERROR;
+    }
+
+    /*
+     * A few of the options require additional processing, such as
+     * style and graphics contexts.
+     */
+
+    i = (int) (arcPtr->start/360.0);
+    arcPtr->start -= i*360.0;
+    if (arcPtr->start < 0) {
+	arcPtr->start += 360.0;
+    }
+    i = (int) (arcPtr->extent/360.0);
+    arcPtr->extent -= i*360.0;
+
+    if ((arcPtr->style != arcUid) && (arcPtr->style != chordUid)
+	    && (arcPtr->style != pieSliceUid)) {
+	Tcl_AppendResult(interp, "bad -style option \"",
+		arcPtr->style, "\": must be arc, chord, or pieslice",
+		(char *) NULL);
+	arcPtr->style = pieSliceUid;
+	return TCL_ERROR;
+    }
+
+    if (arcPtr->width < 0) {
+	arcPtr->width = 1;
+    }
+    if (arcPtr->outlineColor == NULL) {
+	newGC = None;
+    } else {
+	gcValues.foreground = arcPtr->outlineColor->pixel;
+	gcValues.cap_style = CapButt;
+	gcValues.line_width = arcPtr->width;
+	mask = GCForeground|GCCapStyle|GCLineWidth;
+	if (arcPtr->outlineStipple != None) {
+	    gcValues.stipple = arcPtr->outlineStipple;
+	    gcValues.fill_style = FillStippled;
+	    mask |= GCStipple|GCFillStyle;
+	}
+	newGC = Tk_GetGC(tkwin, mask, &gcValues);
+    }
+    if (arcPtr->outlineGC != None) {
+	Tk_FreeGC(Tk_Display(tkwin), arcPtr->outlineGC);
+    }
+    arcPtr->outlineGC = newGC;
+
+    if ((arcPtr->fillColor == NULL) || (arcPtr->style == arcUid)) {
+	newGC = None;
+    } else {
+	gcValues.foreground = arcPtr->fillColor->pixel;
+	if (arcPtr->style == chordUid) {
+	    gcValues.arc_mode = ArcChord;
+	} else {
+	    gcValues.arc_mode = ArcPieSlice;
+	}
+	mask = GCForeground|GCArcMode;
+	if (arcPtr->fillStipple != None) {
+	    gcValues.stipple = arcPtr->fillStipple;
+	    gcValues.fill_style = FillStippled;
+	    mask |= GCStipple|GCFillStyle;
+	}
+	newGC = Tk_GetGC(tkwin, mask, &gcValues);
+    }
+    if (arcPtr->fillGC != None) {
+	Tk_FreeGC(Tk_Display(tkwin), arcPtr->fillGC);
+    }
+    arcPtr->fillGC = newGC;
+
+    ComputeArcBbox(canvas, arcPtr);
+    return TCL_OK;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * DeleteArc --
+ *
+ *	This procedure is called to clean up the data structure
+ *	associated with a arc item.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Resources associated with itemPtr are released.
+ *
+ *--------------------------------------------------------------
+ */
+
+static void
+DeleteArc(canvas, itemPtr, display)
+    Tk_Canvas canvas;			/* Info about overall canvas. */
+    Tk_Item *itemPtr;			/* Item that is being deleted. */
+    Display *display;			/* Display containing window for
+					 * canvas. */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+
+    if (arcPtr->numOutlinePoints != 0) {
+	ckfree((char *) arcPtr->outlinePtr);
+    }
+    if (arcPtr->outlineColor != NULL) {
+	Tk_FreeColor(arcPtr->outlineColor);
+    }
+    if (arcPtr->fillColor != NULL) {
+	Tk_FreeColor(arcPtr->fillColor);
+    }
+    if (arcPtr->fillStipple != None) {
+	Tk_FreeBitmap(display, arcPtr->fillStipple);
+    }
+    if (arcPtr->outlineStipple != None) {
+	Tk_FreeBitmap(display, arcPtr->outlineStipple);
+    }
+    if (arcPtr->outlineGC != None) {
+	Tk_FreeGC(display, arcPtr->outlineGC);
+    }
+    if (arcPtr->fillGC != None) {
+	Tk_FreeGC(display, arcPtr->fillGC);
+    }
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * ComputeArcBbox --
+ *
+ *	This procedure is invoked to compute the bounding box of
+ *	all the pixels that may be drawn as part of an arc.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The fields x1, y1, x2, and y2 are updated in the header
+ *	for itemPtr.
+ *
+ *--------------------------------------------------------------
+ */
+
+	/* ARGSUSED */
+static void
+ComputeArcBbox(canvas, arcPtr)
+    Tk_Canvas canvas;			/* Canvas that contains item. */
+    ArcItem *arcPtr;			/* Item whose bbox is to be
+					 * recomputed. */
+{
+    double tmp, center[2], point[2];
+
+    /*
+     * Make sure that the first coordinates are the lowest ones.
+     */
+
+    if (arcPtr->bbox[1] > arcPtr->bbox[3]) {
+	double tmp;
+	tmp = arcPtr->bbox[3];
+	arcPtr->bbox[3] = arcPtr->bbox[1];
+	arcPtr->bbox[1] = tmp;
+    }
+    if (arcPtr->bbox[0] > arcPtr->bbox[2]) {
+	double tmp;
+	tmp = arcPtr->bbox[2];
+	arcPtr->bbox[2] = arcPtr->bbox[0];
+	arcPtr->bbox[0] = tmp;
+    }
+
+    ComputeArcOutline(arcPtr);
+
+    /*
+     * To compute the bounding box, start with the the bbox formed
+     * by the two endpoints of the arc.  Then add in the center of
+     * the arc's oval (if relevant) and the 3-o'clock, 6-o'clock,
+     * 9-o'clock, and 12-o'clock positions, if they are relevant.
+     */
+
+    arcPtr->header.x1 = arcPtr->header.x2 = (int) arcPtr->center1[0];
+    arcPtr->header.y1 = arcPtr->header.y2 = (int) arcPtr->center1[1];
+    TkIncludePoint((Tk_Item *) arcPtr, arcPtr->center2);
+    center[0] = (arcPtr->bbox[0] + arcPtr->bbox[2])/2;
+    center[1] = (arcPtr->bbox[1] + arcPtr->bbox[3])/2;
+    if (arcPtr->style != arcUid) {
+	TkIncludePoint((Tk_Item *) arcPtr, center);
+    }
+
+    tmp = -arcPtr->start;
+    if (tmp < 0) {
+	tmp += 360.0;
+    }
+    if ((tmp < arcPtr->extent) || ((tmp-360) > arcPtr->extent)) {
+	point[0] = arcPtr->bbox[2];
+	point[1] = center[1];
+	TkIncludePoint((Tk_Item *) arcPtr, point);
+    }
+    tmp = 90.0 - arcPtr->start;
+    if (tmp < 0) {
+	tmp += 360.0;
+    }
+    if ((tmp < arcPtr->extent) || ((tmp-360) > arcPtr->extent)) {
+	point[0] = center[0];
+	point[1] = arcPtr->bbox[1];
+	TkIncludePoint((Tk_Item *) arcPtr, point);
+    }
+    tmp = 180.0 - arcPtr->start;
+    if (tmp < 0) {
+	tmp += 360.0;
+    }
+    if ((tmp < arcPtr->extent) || ((tmp-360) > arcPtr->extent)) {
+	point[0] = arcPtr->bbox[0];
+	point[1] = center[1];
+	TkIncludePoint((Tk_Item *) arcPtr, point);
+    }
+    tmp = 270.0 - arcPtr->start;
+    if (tmp < 0) {
+	tmp += 360.0;
+    }
+    if ((tmp < arcPtr->extent) || ((tmp-360) > arcPtr->extent)) {
+	point[0] = center[0];
+	point[1] = arcPtr->bbox[3];
+	TkIncludePoint((Tk_Item *) arcPtr, point);
+    }
+
+    /*
+     * Lastly, expand by the width of the arc (if the arc's outline is
+     * being drawn) and add one extra pixel just for safety.
+     */
+
+    if (arcPtr->outlineColor == NULL) {
+	tmp = 1;
+    } else {
+	tmp = (arcPtr->width + 1)/2 + 1;
+    }
+    arcPtr->header.x1 -= (int) tmp;
+    arcPtr->header.y1 -= (int) tmp;
+    arcPtr->header.x2 += (int) tmp;
+    arcPtr->header.y2 += (int) tmp;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * DisplayArc --
+ *
+ *	This procedure is invoked to draw an arc item in a given
+ *	drawable.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	ItemPtr is drawn in drawable using the transformation
+ *	information in canvas.
+ *
+ *--------------------------------------------------------------
+ */
+
+static void
+DisplayArc(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). */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+    short x1, y1, x2, y2;
+    int start, extent;
+
+    /*
+     * Compute the screen coordinates of the bounding box for the item,
+     * plus integer values for the angles.
+     */
+
+    Tk_CanvasDrawableCoords(canvas, arcPtr->bbox[0], arcPtr->bbox[1],
+	    &x1, &y1);
+    Tk_CanvasDrawableCoords(canvas, arcPtr->bbox[2], arcPtr->bbox[3],
+	    &x2, &y2);
+    if (x2 <= x1) {
+	x2 = x1+1;
+    }
+    if (y2 <= y1) {
+	y2 = y1+1;
+    }
+    start = (int) ((64*arcPtr->start) + 0.5);
+    extent = (int) ((64*arcPtr->extent) + 0.5);
+
+    /*
+     * Display filled arc first (if wanted), then outline.  If the extent
+     * is zero then don't invoke XFillArc or XDrawArc, since this causes
+     * some window servers to crash and should be a no-op anyway.
+     */
+
+    if ((arcPtr->fillGC != None) && (extent != 0)) {
+	if (arcPtr->fillStipple != None) {
+	    Tk_CanvasSetStippleOrigin(canvas, arcPtr->fillGC);
+	}
+	XFillArc(display, drawable, arcPtr->fillGC, x1, y1, (unsigned) (x2-x1),
+		(unsigned) (y2-y1), start, extent);
+	if (arcPtr->fillStipple != None) {
+	    XSetTSOrigin(display, arcPtr->fillGC, 0, 0);
+	}
+    }
+    if (arcPtr->outlineGC != None) {
+	if (arcPtr->outlineStipple != None) {
+	    Tk_CanvasSetStippleOrigin(canvas, arcPtr->outlineGC);
+	}
+	if (extent != 0) {
+	    XDrawArc(display, drawable, arcPtr->outlineGC, x1, y1,
+		    (unsigned) (x2-x1), (unsigned) (y2-y1), start, extent);
+	}
+
+	/*
+	 * If the outline width is very thin, don't use polygons to draw
+	 * the linear parts of the outline (this often results in nothing
+	 * being displayed); just draw lines instead.
+	 */
+
+	if (arcPtr->width <= 2) {
+	    Tk_CanvasDrawableCoords(canvas, arcPtr->center1[0],
+		    arcPtr->center1[1], &x1, &y1);
+	    Tk_CanvasDrawableCoords(canvas, arcPtr->center2[0],
+		    arcPtr->center2[1], &x2, &y2);
+
+	    if (arcPtr->style == chordUid) {
+		XDrawLine(display, drawable, arcPtr->outlineGC,
+			x1, y1, x2, y2);
+	    } else if (arcPtr->style == pieSliceUid) {
+		short cx, cy;
+
+		Tk_CanvasDrawableCoords(canvas,
+			(arcPtr->bbox[0] + arcPtr->bbox[2])/2.0,
+			(arcPtr->bbox[1] + arcPtr->bbox[3])/2.0, &cx, &cy);
+		XDrawLine(display, drawable, arcPtr->outlineGC,
+			cx, cy, x1, y1);
+		XDrawLine(display, drawable, arcPtr->outlineGC,
+			cx, cy, x2, y2);
+	    }
+	} else {
+	    if (arcPtr->style == chordUid) {
+		TkFillPolygon(canvas, arcPtr->outlinePtr, CHORD_OUTLINE_PTS,
+			display, drawable, arcPtr->outlineGC, None);
+	    } else if (arcPtr->style == pieSliceUid) {
+		TkFillPolygon(canvas, arcPtr->outlinePtr, PIE_OUTLINE1_PTS,
+			display, drawable, arcPtr->outlineGC, None);
+		TkFillPolygon(canvas, arcPtr->outlinePtr + 2*PIE_OUTLINE1_PTS,
+			PIE_OUTLINE2_PTS, display, drawable, arcPtr->outlineGC,
+			None);
+	    }
+	}
+	if (arcPtr->outlineStipple != None) {
+	    XSetTSOrigin(display, arcPtr->outlineGC, 0, 0);
+	}
+    }
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * ArcToPoint --
+ *
+ *	Computes the distance from a given point to a given
+ *	arc, in canvas units.
+ *
+ * Results:
+ *	The return value is 0 if the point whose x and y coordinates
+ *	are coordPtr[0] and coordPtr[1] is inside the arc.  If the
+ *	point isn't inside the arc then the return value is the
+ *	distance from the point to the arc.  If itemPtr is filled,
+ *	then anywhere in the interior is considered "inside"; if
+ *	itemPtr isn't filled, then "inside" means only the area
+ *	occupied by the outline.
+ *
+ * Side effects:
+ *	None.
+ *
+ *--------------------------------------------------------------
+ */
+
+	/* ARGSUSED */
+static double
+ArcToPoint(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. */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+    double vertex[2], pointAngle, diff, dist, newDist;
+    double poly[8], polyDist, width, t1, t2;
+    int filled, angleInRange;
+
+    /*
+     * See if the point is within the angular range of the arc.
+     * Remember, X angles are backwards from the way we'd normally
+     * think of them.  Also, compensate for any eccentricity of
+     * the oval.
+     */
+
+    vertex[0] = (arcPtr->bbox[0] + arcPtr->bbox[2])/2.0;
+    vertex[1] = (arcPtr->bbox[1] + arcPtr->bbox[3])/2.0;
+    t1 = (pointPtr[1] - vertex[1])/(arcPtr->bbox[3] - arcPtr->bbox[1]);
+    t2 = (pointPtr[0] - vertex[0])/(arcPtr->bbox[2] - arcPtr->bbox[0]);
+    if ((t1 == 0.0) && (t2 == 0.0)) {
+	pointAngle = 0;
+    } else {
+	pointAngle = -atan2(t1, t2)*180/PI;
+    }
+    diff = pointAngle - arcPtr->start;
+    diff -= ((int) (diff/360.0) * 360.0);
+    if (diff < 0) {
+	diff += 360.0;
+    }
+    angleInRange = (diff <= arcPtr->extent) ||
+	    ((arcPtr->extent < 0) && ((diff - 360.0) >= arcPtr->extent));
+
+    /*
+     * Now perform different tests depending on what kind of arc
+     * we're dealing with.
+     */
+
+    if (arcPtr->style == arcUid) {
+	if (angleInRange) {
+	    return TkOvalToPoint(arcPtr->bbox, (double) arcPtr->width,
+		    0, pointPtr);
+	}
+	dist = hypot(pointPtr[0] - arcPtr->center1[0],
+		pointPtr[1] - arcPtr->center1[1]);
+	newDist = hypot(pointPtr[0] - arcPtr->center2[0],
+		pointPtr[1] - arcPtr->center2[1]);
+	if (newDist < dist) {
+	    return newDist;
+	}
+	return dist;
+    }
+
+    if ((arcPtr->fillGC != None) || (arcPtr->outlineGC == None)) {
+	filled = 1;
+    } else {
+	filled = 0;
+    }
+    if (arcPtr->outlineGC == None) {
+	width = 0.0;
+    } else {
+	width = arcPtr->width;
+    }
+
+    if (arcPtr->style == pieSliceUid) {
+	if (width > 1.0) {
+	    dist = TkPolygonToPoint(arcPtr->outlinePtr, PIE_OUTLINE1_PTS,
+		    pointPtr);
+	    newDist = TkPolygonToPoint(arcPtr->outlinePtr + 2*PIE_OUTLINE1_PTS,
+			PIE_OUTLINE2_PTS, pointPtr);
+	} else {
+	    dist = TkLineToPoint(vertex, arcPtr->center1, pointPtr);
+	    newDist = TkLineToPoint(vertex, arcPtr->center2, pointPtr);
+	}
+	if (newDist < dist) {
+	    dist = newDist;
+	}
+	if (angleInRange) {
+	    newDist = TkOvalToPoint(arcPtr->bbox, width, filled, pointPtr);
+	    if (newDist < dist) {
+		dist = newDist;
+	    }
+	}
+	return dist;
+    }
+
+    /*
+     * This is a chord-style arc.  We have to deal specially with the
+     * triangular piece that represents the difference between a
+     * chord-style arc and a pie-slice arc (for small angles this piece
+     * is excluded here where it would be included for pie slices;
+     * for large angles the piece is included here but would be
+     * excluded for pie slices).
+     */
+
+    if (width > 1.0) {
+	dist = TkPolygonToPoint(arcPtr->outlinePtr, CHORD_OUTLINE_PTS,
+		    pointPtr);
+    } else {
+	dist = TkLineToPoint(arcPtr->center1, arcPtr->center2, pointPtr);
+    }
+    poly[0] = poly[6] = vertex[0];
+    poly[1] = poly[7] = vertex[1];
+    poly[2] = arcPtr->center1[0];
+    poly[3] = arcPtr->center1[1];
+    poly[4] = arcPtr->center2[0];
+    poly[5] = arcPtr->center2[1];
+    polyDist = TkPolygonToPoint(poly, 4, pointPtr);
+    if (angleInRange) {
+	if ((arcPtr->extent < -180.0) || (arcPtr->extent > 180.0)
+		|| (polyDist > 0.0)) {
+	    newDist = TkOvalToPoint(arcPtr->bbox, width, filled, pointPtr);
+	    if (newDist < dist) {
+		dist = newDist;
+	    }
+	}
+    } else {
+	if ((arcPtr->extent < -180.0) || (arcPtr->extent > 180.0)) {
+	    if (filled && (polyDist < dist)) {
+		dist = polyDist;
+	    }
+	}
+    }
+    return dist;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * ArcToArea --
+ *
+ *	This procedure is called to determine whether an item
+ *	lies entirely inside, entirely outside, or overlapping
+ *	a given 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
+ArcToArea(canvas, itemPtr, rectPtr)
+    Tk_Canvas canvas;		/* Canvas containing item. */
+    Tk_Item *itemPtr;		/* Item to check against arc. */
+    double *rectPtr;		/* Pointer to array of four coordinates
+				 * (x1, y1, x2, y2) describing rectangular
+				 * area.  */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+    double rx, ry;		/* Radii for transformed oval:  these define
+				 * an oval centered at the origin. */
+    double tRect[4];		/* Transformed version of x1, y1, x2, y2,
+				 * for coord. system where arc is centered
+				 * on the origin. */
+    double center[2], width, angle, tmp;
+    double points[20], *pointPtr;
+    int numPoints, filled;
+    int inside;			/* Non-zero means every test so far suggests
+				 * that arc is inside rectangle.  0 means
+				 * every test so far shows arc to be outside
+				 * of rectangle. */
+    int newInside;
+
+    if ((arcPtr->fillGC != None) || (arcPtr->outlineGC == None)) {
+	filled = 1;
+    } else {
+	filled = 0;
+    }
+    if (arcPtr->outlineGC == None) {
+	width = 0.0;
+    } else {
+	width = arcPtr->width;
+    }
+
+    /*
+     * Transform both the arc and the rectangle so that the arc's oval
+     * is centered on the origin.
+     */
+
+    center[0] = (arcPtr->bbox[0] + arcPtr->bbox[2])/2.0;
+    center[1] = (arcPtr->bbox[1] + arcPtr->bbox[3])/2.0;
+    tRect[0] = rectPtr[0] - center[0];
+    tRect[1] = rectPtr[1] - center[1];
+    tRect[2] = rectPtr[2] - center[0];
+    tRect[3] = rectPtr[3] - center[1];
+    rx = arcPtr->bbox[2] - center[0] + width/2.0;
+    ry = arcPtr->bbox[3] - center[1] + width/2.0;
+
+    /*
+     * Find the extreme points of the arc and see whether these are all
+     * inside the rectangle (in which case we're done), partly in and
+     * partly out (in which case we're done), or all outside (in which
+     * case we have more work to do).  The extreme points include the
+     * following, which are checked in order:
+     *
+     * 1. The outside points of the arc, corresponding to start and
+     *	  extent.
+     * 2. The center of the arc (but only in pie-slice mode).
+     * 3. The 12, 3, 6, and 9-o'clock positions (but only if the arc
+     *    includes those angles).
+     */
+
+    pointPtr = points;
+    angle = -arcPtr->start*(PI/180.0);
+    pointPtr[0] = rx*cos(angle);
+    pointPtr[1] = ry*sin(angle);
+    angle += -arcPtr->extent*(PI/180.0);
+    pointPtr[2] = rx*cos(angle);
+    pointPtr[3] = ry*sin(angle);
+    numPoints = 2;
+    pointPtr += 4;
+
+    if ((arcPtr->style == pieSliceUid) && (arcPtr->extent < 180.0)) {
+	pointPtr[0] = 0.0;
+	pointPtr[1] = 0.0;
+	numPoints++;
+	pointPtr += 2;
+    }
+
+    tmp = -arcPtr->start;
+    if (tmp < 0) {
+	tmp += 360.0;
+    }
+    if ((tmp < arcPtr->extent) || ((tmp-360) > arcPtr->extent)) {
+	pointPtr[0] = rx;
+	pointPtr[1] = 0.0;
+	numPoints++;
+	pointPtr += 2;
+    }
+    tmp = 90.0 - arcPtr->start;
+    if (tmp < 0) {
+	tmp += 360.0;
+    }
+    if ((tmp < arcPtr->extent) || ((tmp-360) > arcPtr->extent)) {
+	pointPtr[0] = 0.0;
+	pointPtr[1] = -ry;
+	numPoints++;
+	pointPtr += 2;
+    }
+    tmp = 180.0 - arcPtr->start;
+    if (tmp < 0) {
+	tmp += 360.0;
+    }
+    if ((tmp < arcPtr->extent) || ((tmp-360) > arcPtr->extent)) {
+	pointPtr[0] = -rx;
+	pointPtr[1] = 0.0;
+	numPoints++;
+	pointPtr += 2;
+    }
+    tmp = 270.0 - arcPtr->start;
+    if (tmp < 0) {
+	tmp += 360.0;
+    }
+    if ((tmp < arcPtr->extent) || ((tmp-360) > arcPtr->extent)) {
+	pointPtr[0] = 0.0;
+	pointPtr[1] = ry;
+	numPoints++;
+    }
+
+    /*
+     * Now that we've located the extreme points, loop through them all
+     * to see which are inside the rectangle.
+     */
+
+    inside = (points[0] > tRect[0]) && (points[0] < tRect[2])
+	    && (points[1] > tRect[1]) && (points[1] < tRect[3]);
+    for (pointPtr = points+2; numPoints > 1; pointPtr += 2, numPoints--) {
+	newInside = (pointPtr[0] > tRect[0]) && (pointPtr[0] < tRect[2])
+		&& (pointPtr[1] > tRect[1]) && (pointPtr[1] < tRect[3]);
+	if (newInside != inside) {
+	    return 0;
+	}
+    }
+
+    if (inside) {
+	return 1;
+    }
+
+    /*
+     * So far, oval appears to be outside rectangle, but can't yet tell
+     * for sure.  Next, test each of the four sides of the rectangle
+     * against the bounding region for the arc.  If any intersections
+     * are found, then return "overlapping".  First, test against the
+     * polygon(s) forming the sides of a chord or pie-slice.
+     */
+
+    if (arcPtr->style == pieSliceUid) {
+	if (width >= 1.0) {
+	    if (TkPolygonToArea(arcPtr->outlinePtr, PIE_OUTLINE1_PTS,
+		    rectPtr) != -1)  {
+		return 0;
+	    }
+	    if (TkPolygonToArea(arcPtr->outlinePtr + 2*PIE_OUTLINE1_PTS,
+		    PIE_OUTLINE2_PTS, rectPtr) != -1) {
+		return 0;
+	    }
+	} else {
+	    if ((TkLineToArea(center, arcPtr->center1, rectPtr) != -1) ||
+		    (TkLineToArea(center, arcPtr->center2, rectPtr) != -1)) {
+		return 0;
+	    }
+	}
+    } else if (arcPtr->style == chordUid) {
+	if (width >= 1.0) {
+	    if (TkPolygonToArea(arcPtr->outlinePtr, CHORD_OUTLINE_PTS,
+		    rectPtr) != -1) {
+		return 0;
+	    }
+	} else {
+	    if (TkLineToArea(arcPtr->center1, arcPtr->center2,
+		    rectPtr) != -1) {
+		return 0;
+	    }
+	}
+    }
+
+    /*
+     * Next check for overlap between each of the four sides and the
+     * outer perimiter of the arc.  If the arc isn't filled, then also
+     * check the inner perimeter of the arc.
+     */
+
+    if (HorizLineToArc(tRect[0], tRect[2], tRect[1], rx, ry, arcPtr->start,
+		arcPtr->extent)
+	    || HorizLineToArc(tRect[0], tRect[2], tRect[3], rx, ry,
+		arcPtr->start, arcPtr->extent)
+	    || VertLineToArc(tRect[0], tRect[1], tRect[3], rx, ry,
+		arcPtr->start, arcPtr->extent)
+	    || VertLineToArc(tRect[2], tRect[1], tRect[3], rx, ry,
+		arcPtr->start, arcPtr->extent)) {
+	return 0;
+    }
+    if ((width > 1.0) && !filled) {
+	rx -= width;
+	ry -= width;
+	if (HorizLineToArc(tRect[0], tRect[2], tRect[1], rx, ry, arcPtr->start,
+		    arcPtr->extent)
+		|| HorizLineToArc(tRect[0], tRect[2], tRect[3], rx, ry,
+		    arcPtr->start, arcPtr->extent)
+		|| VertLineToArc(tRect[0], tRect[1], tRect[3], rx, ry,
+		    arcPtr->start, arcPtr->extent)
+		|| VertLineToArc(tRect[2], tRect[1], tRect[3], rx, ry,
+		    arcPtr->start, arcPtr->extent)) {
+	    return 0;
+	}
+    }
+
+    /*
+     * The arc still appears to be totally disjoint from the rectangle,
+     * but it's also possible that the rectangle is totally inside the arc.
+     * Do one last check, which is to check one point of the rectangle
+     * to see if it's inside the arc.  If it is, we've got overlap.  If
+     * it isn't, the arc's really outside the rectangle.
+     */
+
+    if (ArcToPoint(canvas, itemPtr, rectPtr) == 0.0) {
+	return 0;
+    }
+    return -1;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * ScaleArc --
+ *
+ *	This procedure is invoked to rescale an arc item.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The arc 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
+ScaleArc(canvas, itemPtr, originX, originY, scaleX, scaleY)
+    Tk_Canvas canvas;			/* Canvas containing arc. */
+    Tk_Item *itemPtr;			/* Arc 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. */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+
+    arcPtr->bbox[0] = originX + scaleX*(arcPtr->bbox[0] - originX);
+    arcPtr->bbox[1] = originY + scaleY*(arcPtr->bbox[1] - originY);
+    arcPtr->bbox[2] = originX + scaleX*(arcPtr->bbox[2] - originX);
+    arcPtr->bbox[3] = originY + scaleY*(arcPtr->bbox[3] - originY);
+    ComputeArcBbox(canvas, arcPtr);
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * TranslateArc --
+ *
+ *	This procedure is called to move an arc by a given amount.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The position of the arc is offset by (xDelta, yDelta), and
+ *	the bounding box is updated in the generic part of the item
+ *	structure.
+ *
+ *--------------------------------------------------------------
+ */
+
+static void
+TranslateArc(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. */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+
+    arcPtr->bbox[0] += deltaX;
+    arcPtr->bbox[1] += deltaY;
+    arcPtr->bbox[2] += deltaX;
+    arcPtr->bbox[3] += deltaY;
+    ComputeArcBbox(canvas, arcPtr);
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * ComputeArcOutline --
+ *
+ *	This procedure creates a polygon describing everything in
+ *	the outline for an arc except what's in the curved part.
+ *	For a "pie slice" arc this is a V-shaped chunk, and for
+ *	a "chord" arc this is a linear chunk (with cutaway corners).
+ *	For "arc" arcs, this stuff isn't relevant.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The information at arcPtr->outlinePtr gets modified, and
+ *	storage for arcPtr->outlinePtr may be allocated or freed.
+ *
+ *--------------------------------------------------------------
+ */
+
+static void
+ComputeArcOutline(arcPtr)
+    ArcItem *arcPtr;			/* Information about arc. */
+{
+    double sin1, cos1, sin2, cos2, angle, halfWidth;
+    double boxWidth, boxHeight;
+    double vertex[2], corner1[2], corner2[2];
+    double *outlinePtr;
+
+    /*
+     * Make sure that the outlinePtr array is large enough to hold
+     * either a chord or pie-slice outline.
+     */
+
+    if (arcPtr->numOutlinePoints == 0) {
+	arcPtr->outlinePtr = (double *) ckalloc((unsigned)
+		(26 * sizeof(double)));
+	arcPtr->numOutlinePoints = 22;
+    }
+    outlinePtr = arcPtr->outlinePtr;
+
+    /*
+     * First compute the two points that lie at the centers of
+     * the ends of the curved arc segment, which are marked with
+     * X's in the figure below:
+     *
+     *
+     *				  * * *
+     *			      *          *
+     *			   *      * *      *
+     *			 *    *         *    *
+     *			*   *             *   *
+     *			 X *               * X
+     *
+     * The code is tricky because the arc can be ovular in shape.
+     * It computes the position for a unit circle, and then
+     * scales to fit the shape of the arc's bounding box.
+     *
+     * Also, watch out because angles go counter-clockwise like you
+     * might expect, but the y-coordinate system is inverted.  To
+     * handle this, just negate the angles in all the computations.
+     */
+
+    boxWidth = arcPtr->bbox[2] - arcPtr->bbox[0];
+    boxHeight = arcPtr->bbox[3] - arcPtr->bbox[1];
+    angle = -arcPtr->start*PI/180.0;
+    sin1 = sin(angle);
+    cos1 = cos(angle);
+    angle -= arcPtr->extent*PI/180.0;
+    sin2 = sin(angle);
+    cos2 = cos(angle);
+    vertex[0] = (arcPtr->bbox[0] + arcPtr->bbox[2])/2.0;
+    vertex[1] = (arcPtr->bbox[1] + arcPtr->bbox[3])/2.0;
+    arcPtr->center1[0] = vertex[0] + cos1*boxWidth/2.0;
+    arcPtr->center1[1] = vertex[1] + sin1*boxHeight/2.0;
+    arcPtr->center2[0] = vertex[0] + cos2*boxWidth/2.0;
+    arcPtr->center2[1] = vertex[1] + sin2*boxHeight/2.0;
+
+    /*
+     * Next compute the "outermost corners" of the arc, which are
+     * marked with X's in the figure below:
+     *
+     *				  * * *
+     *			      *          *
+     *			   *      * *      *
+     *			 *    *         *    *
+     *			X   *             *   X
+     *			   *               *
+     *
+     * The code below is tricky because it has to handle eccentricity
+     * in the shape of the oval.  The key in the code below is to
+     * realize that the slope of the line from arcPtr->center1 to corner1
+     * is (boxWidth*sin1)/(boxHeight*cos1), and similarly for arcPtr->center2
+     * and corner2.  These formulas can be computed from the formula for
+     * the oval.
+     */
+
+    halfWidth = arcPtr->width/2.0;
+    if (((boxWidth*sin1) == 0.0) && ((boxHeight*cos1) == 0.0)) {
+	angle = 0.0;
+    } else {
+	angle = atan2(boxWidth*sin1, boxHeight*cos1);
+    }
+    corner1[0] = arcPtr->center1[0] + cos(angle)*halfWidth;
+    corner1[1] = arcPtr->center1[1] + sin(angle)*halfWidth;
+    if (((boxWidth*sin2) == 0.0) && ((boxHeight*cos2) == 0.0)) {
+	angle = 0.0;
+    } else {
+	angle = atan2(boxWidth*sin2, boxHeight*cos2);
+    }
+    corner2[0] = arcPtr->center2[0] + cos(angle)*halfWidth;
+    corner2[1] = arcPtr->center2[1] + sin(angle)*halfWidth;
+
+    /*
+     * For a chord outline, generate a six-sided polygon with three
+     * points for each end of the chord.  The first and third points
+     * for each end are butt points generated on either side of the
+     * center point.  The second point is the corner point.
+     */
+
+    if (arcPtr->style == chordUid) {
+	outlinePtr[0] = outlinePtr[12] = corner1[0];
+	outlinePtr[1] = outlinePtr[13] = corner1[1];
+	TkGetButtPoints(arcPtr->center2, arcPtr->center1,
+		(double) arcPtr->width, 0, outlinePtr+10, outlinePtr+2);
+	outlinePtr[4] = arcPtr->center2[0] + outlinePtr[2]
+		- arcPtr->center1[0];
+	outlinePtr[5] = arcPtr->center2[1] + outlinePtr[3]
+		- arcPtr->center1[1];
+	outlinePtr[6] = corner2[0];
+	outlinePtr[7] = corner2[1];
+	outlinePtr[8] = arcPtr->center2[0] + outlinePtr[10]
+		- arcPtr->center1[0];
+	outlinePtr[9] = arcPtr->center2[1] + outlinePtr[11]
+		- arcPtr->center1[1];
+    } else if (arcPtr->style == pieSliceUid) {
+	/*
+	 * For pie slices, generate two polygons, one for each side
+	 * of the pie slice.  The first arm has a shape like this,
+	 * where the center of the oval is X, arcPtr->center1 is at Y, and
+	 * corner1 is at Z:
+	 *
+	 *	 _____________________
+	 *	|		      \
+	 *	|		       \
+	 *	X		     Y  Z
+	 *	|		       /
+	 *	|_____________________/
+	 *
+	 */
+
+	TkGetButtPoints(arcPtr->center1, vertex, (double) arcPtr->width, 0,
+		outlinePtr, outlinePtr+2);
+	outlinePtr[4] = arcPtr->center1[0] + outlinePtr[2] - vertex[0];
+	outlinePtr[5] = arcPtr->center1[1] + outlinePtr[3] - vertex[1];
+	outlinePtr[6] = corner1[0];
+	outlinePtr[7] = corner1[1];
+	outlinePtr[8] = arcPtr->center1[0] + outlinePtr[0] - vertex[0];
+	outlinePtr[9] = arcPtr->center1[1] + outlinePtr[1] - vertex[1];
+	outlinePtr[10] = outlinePtr[0];
+	outlinePtr[11] = outlinePtr[1];
+
+	/*
+	 * The second arm has a shape like this:
+	 *
+	 *
+	 *	   ______________________
+	 *	  /			  \
+	 *	 /			   \
+	 *	Z  Y			X  /
+	 *	 \			  /
+	 *	  \______________________/
+	 *
+	 * Similar to above X is the center of the oval/circle, Y is
+	 * arcPtr->center2, and Z is corner2.  The extra jog out to the left
+	 * of X is needed in or to produce a butted joint with the
+	 * first arm;  the corner to the right of X is one of the
+	 * first two points of the first arm, depending on extent.
+	 */
+
+	TkGetButtPoints(arcPtr->center2, vertex, (double) arcPtr->width, 0,
+		outlinePtr+12, outlinePtr+16);
+	if ((arcPtr->extent > 180) ||
+		((arcPtr->extent < 0) && (arcPtr->extent > -180))) {
+	    outlinePtr[14] = outlinePtr[0];
+	    outlinePtr[15] = outlinePtr[1];
+	} else {
+	    outlinePtr[14] = outlinePtr[2];
+	    outlinePtr[15] = outlinePtr[3];
+	}
+	outlinePtr[18] = arcPtr->center2[0] + outlinePtr[16] - vertex[0];
+	outlinePtr[19] = arcPtr->center2[1] + outlinePtr[17] - vertex[1];
+	outlinePtr[20] = corner2[0];
+	outlinePtr[21] = corner2[1];
+	outlinePtr[22] = arcPtr->center2[0] + outlinePtr[12] - vertex[0];
+	outlinePtr[23] = arcPtr->center2[1] + outlinePtr[13] - vertex[1];
+	outlinePtr[24] = outlinePtr[12];
+	outlinePtr[25] = outlinePtr[13];
+    }
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * HorizLineToArc --
+ *
+ *	Determines whether a horizontal line segment intersects
+ *	a given arc.
+ *
+ * Results:
+ *	The return value is 1 if the given line intersects the
+ *	infinitely-thin arc section defined by rx, ry, start,
+ *	and extent, and 0 otherwise.  Only the perimeter of the
+ *	arc is checked: interior areas (e.g. pie-slice or chord)
+ *	are not checked.
+ *
+ * Side effects:
+ *	None.
+ *
+ *--------------------------------------------------------------
+ */
+
+static int
+HorizLineToArc(x1, x2, y, rx, ry, start, extent)
+    double x1, x2;		/* X-coords of endpoints of line segment. 
+				 * X1 must be <= x2. */
+    double y;			/* Y-coordinate of line segment. */
+    double rx, ry;		/* These x- and y-radii define an oval
+				 * centered at the origin. */
+    double start, extent;	/* Angles that define extent of arc, in
+				 * the standard fashion for this module. */
+{
+    double tmp;
+    double tx, ty;		/* Coordinates of intersection point in
+				 * transformed coordinate system. */
+    double x;
+
+    /*
+     * Compute the x-coordinate of one possible intersection point
+     * between the arc and the line.  Use a transformed coordinate
+     * system where the oval is a unit circle centered at the origin.
+     * Then scale back to get actual x-coordinate.
+     */
+
+    ty = y/ry;
+    tmp = 1 - ty*ty;
+    if (tmp < 0) {
+	return 0;
+    }
+    tx = sqrt(tmp);
+    x = tx*rx;
+
+    /*
+     * Test both intersection points.
+     */
+
+    if ((x >= x1) && (x <= x2) && AngleInRange(tx, ty, start, extent)) {
+	return 1;
+    }
+    if ((-x >= x1) && (-x <= x2) && AngleInRange(-tx, ty, start, extent)) {
+	return 1;
+    }
+    return 0;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * VertLineToArc --
+ *
+ *	Determines whether a vertical line segment intersects
+ *	a given arc.
+ *
+ * Results:
+ *	The return value is 1 if the given line intersects the
+ *	infinitely-thin arc section defined by rx, ry, start,
+ *	and extent, and 0 otherwise.  Only the perimeter of the
+ *	arc is checked: interior areas (e.g. pie-slice or chord)
+ *	are not checked.
+ *
+ * Side effects:
+ *	None.
+ *
+ *--------------------------------------------------------------
+ */
+
+static int
+VertLineToArc(x, y1, y2, rx, ry, start, extent)
+    double x;			/* X-coordinate of line segment. */
+    double y1, y2;		/* Y-coords of endpoints of line segment. 
+				 * Y1 must be <= y2. */
+    double rx, ry;		/* These x- and y-radii define an oval
+				 * centered at the origin. */
+    double start, extent;	/* Angles that define extent of arc, in
+				 * the standard fashion for this module. */
+{
+    double tmp;
+    double tx, ty;		/* Coordinates of intersection point in
+				 * transformed coordinate system. */
+    double y;
+
+    /*
+     * Compute the y-coordinate of one possible intersection point
+     * between the arc and the line.  Use a transformed coordinate
+     * system where the oval is a unit circle centered at the origin.
+     * Then scale back to get actual y-coordinate.
+     */
+
+    tx = x/rx;
+    tmp = 1 - tx*tx;
+    if (tmp < 0) {
+	return 0;
+    }
+    ty = sqrt(tmp);
+    y = ty*ry;
+
+    /*
+     * Test both intersection points.
+     */
+
+    if ((y > y1) && (y < y2) && AngleInRange(tx, ty, start, extent)) {
+	return 1;
+    }
+    if ((-y > y1) && (-y < y2) && AngleInRange(tx, -ty, start, extent)) {
+	return 1;
+    }
+    return 0;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * AngleInRange --
+ *
+ *	Determine whether the angle from the origin to a given
+ *	point is within a given range.
+ *
+ * Results:
+ *	The return value is 1 if the angle from (0,0) to (x,y)
+ *	is in the range given by start and extent, where angles
+ *	are interpreted in the standard way for ovals (meaning
+ *	backwards from normal interpretation).  Otherwise the
+ *	return value is 0.
+ *
+ * Side effects:
+ *	None.
+ *
+ *--------------------------------------------------------------
+ */
+
+static int
+AngleInRange(x, y, start, extent)
+    double x, y;		/* Coordinate of point;  angle measured
+				 * from origin to here, relative to x-axis. */
+    double start;		/* First angle, degrees, >=0, <=360. */
+    double extent;		/* Size of arc in degrees >=-360, <=360. */
+{
+    double diff;
+
+    if ((x == 0.0) && (y == 0.0)) {
+	return 1;
+    }
+    diff = -atan2(y, x);
+    diff = diff*(180.0/PI) - start;
+    while (diff > 360.0) {
+	diff -= 360.0;
+    }
+    while (diff < 0.0) {
+	diff += 360.0;
+    }
+    if (extent >= 0) {
+	return diff <= extent;
+    }
+    return (diff-360.0) >= extent;
+}
+
+/*
+ *--------------------------------------------------------------
+ *
+ * ArcToPostscript --
+ *
+ *	This procedure is called to generate Postscript for
+ *	arc 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
+ArcToPostscript(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. */
+{
+    ArcItem *arcPtr = (ArcItem *) itemPtr;
+    char buffer[400];
+    double y1, y2, ang1, ang2;
+
+    y1 = Tk_CanvasPsY(canvas, arcPtr->bbox[1]);
+    y2 = Tk_CanvasPsY(canvas, arcPtr->bbox[3]);
+    ang1 = arcPtr->start;
+    ang2 = ang1 + arcPtr->extent;
+    if (ang2 < ang1) {
+	ang1 = ang2;
+	ang2 = arcPtr->start;
+    }
+
+    /*
+     * If the arc is filled, output Postscript for the interior region
+     * of the arc.
+     */
+
+    if (arcPtr->fillGC != None) {
+	sprintf(buffer, "matrix currentmatrix\n%.15g %.15g translate %.15g %.15g scale\n",
+		(arcPtr->bbox[0] + arcPtr->bbox[2])/2, (y1 + y2)/2,
+		(arcPtr->bbox[2] - arcPtr->bbox[0])/2, (y1 - y2)/2);
+	Tcl_AppendResult(interp, buffer, (char *) NULL);
+	if (arcPtr->style == chordUid) {
+	    sprintf(buffer, "0 0 1 %.15g %.15g arc closepath\nsetmatrix\n",
+		    ang1, ang2);
+	} else {
+	    sprintf(buffer,
+		    "0 0 moveto 0 0 1 %.15g %.15g arc closepath\nsetmatrix\n",
+		    ang1, ang2);
+	}
+	Tcl_AppendResult(interp, buffer, (char *) NULL);
+	if (Tk_CanvasPsColor(interp, canvas, arcPtr->fillColor) != TCL_OK) {
+	    return TCL_ERROR;
+	};
+	if (arcPtr->fillStipple != None) {
+	    Tcl_AppendResult(interp, "clip ", (char *) NULL);
+	    if (Tk_CanvasPsStipple(interp, canvas, arcPtr->fillStipple)
+		    != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    if (arcPtr->outlineGC != None) {
+		Tcl_AppendResult(interp, "grestore gsave\n", (char *) NULL);
+	    }
+	} else {
+	    Tcl_AppendResult(interp, "fill\n", (char *) NULL);
+	}
+    }
+
+    /*
+     * If there's an outline for the arc, draw it.
+     */
+
+    if (arcPtr->outlineGC != None) {
+	sprintf(buffer, "matrix currentmatrix\n%.15g %.15g translate %.15g %.15g scale\n",
+		(arcPtr->bbox[0] + arcPtr->bbox[2])/2, (y1 + y2)/2,
+		(arcPtr->bbox[2] - arcPtr->bbox[0])/2, (y1 - y2)/2);
+	Tcl_AppendResult(interp, buffer, (char *) NULL);
+	sprintf(buffer, "0 0 1 %.15g %.15g arc\nsetmatrix\n", ang1, ang2);
+	Tcl_AppendResult(interp, buffer, (char *) NULL);
+	sprintf(buffer, "%d setlinewidth\n0 setlinecap\n", arcPtr->width);
+	Tcl_AppendResult(interp, buffer, (char *) NULL);
+	if (Tk_CanvasPsColor(interp, canvas, arcPtr->outlineColor)
+		!= TCL_OK) {
+	    return TCL_ERROR;
+	}
+	if (arcPtr->outlineStipple != None) {
+	    Tcl_AppendResult(interp, "StrokeClip ", (char *) NULL);
+	    if (Tk_CanvasPsStipple(interp, canvas,
+		    arcPtr->outlineStipple) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	} else {
+	    Tcl_AppendResult(interp, "stroke\n", (char *) NULL);
+	}
+	if (arcPtr->style != arcUid) {
+	    Tcl_AppendResult(interp, "grestore gsave\n", (char *) NULL);
+	    if (arcPtr->style == chordUid) {
+		Tk_CanvasPsPath(interp, canvas, arcPtr->outlinePtr,
+			CHORD_OUTLINE_PTS);
+	    } else {
+		Tk_CanvasPsPath(interp, canvas, arcPtr->outlinePtr,
+			PIE_OUTLINE1_PTS);
+		if (Tk_CanvasPsColor(interp, canvas, arcPtr->outlineColor)
+			!= TCL_OK) {
+		    return TCL_ERROR;
+		}
+		if (arcPtr->outlineStipple != None) {
+		    Tcl_AppendResult(interp, "clip ", (char *) NULL);
+		    if (Tk_CanvasPsStipple(interp, canvas,
+			    arcPtr->outlineStipple) != TCL_OK) {
+			return TCL_ERROR;
+		    }
+		} else {
+		    Tcl_AppendResult(interp, "fill\n", (char *) NULL);
+		}
+		Tcl_AppendResult(interp, "grestore gsave\n", (char *) NULL);
+		Tk_CanvasPsPath(interp, canvas,
+			arcPtr->outlinePtr + 2*PIE_OUTLINE1_PTS,
+			PIE_OUTLINE2_PTS);
+	    }
+	    if (Tk_CanvasPsColor(interp, canvas, arcPtr->outlineColor)
+		    != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    if (arcPtr->outlineStipple != None) {
+		Tcl_AppendResult(interp, "clip ", (char *) NULL);
+		if (Tk_CanvasPsStipple(interp, canvas,
+			arcPtr->outlineStipple) != TCL_OK) {
+		    return TCL_ERROR;
+		}
+	    } else {
+		Tcl_AppendResult(interp, "fill\n", (char *) NULL);
+	    }
+	}
+    }
+
+    return TCL_OK;
+}