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[micropolis] / src / tk / tk3d.c

/* 
 * tk3D.c --
 *
 *      This module provides procedures to draw borders in
 *      the three-dimensional Motif style.
 *
 * Copyright 1990 Regents of the University of California.
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies.  The University of California
 * makes no representations about the suitability of this
 * software for any purpose.  It is provided "as is" without
 * express or implied warranty.
 */

#ifndef lint
static char rcsid[] = "$Header: /user6/ouster/wish/RCS/tk3d.c,v 1.30 92/06/15 14:28:18 ouster Exp $ SPRITE (Berkeley)";
#endif

#include "tkconfig.h"
#include "tk.h"

/*
 * One of the following data structures is allocated for
 * each 3-D border currently in use.  Structures of this
 * type are indexed by borderTable, so that a single
 * structure can be shared for several uses.
 */

typedef struct {
    Display *display;           /* Display for which the resources
                                 * below are allocated. */
    int refCount;               /* Number of different users of
                                 * this border.  */
    XColor *bgColorPtr;         /* Background color (intensity
                                 * between lightColorPtr and
                                 * darkColorPtr). */
    XColor *lightColorPtr;      /* Color used for lighter areas of
                                 * border (must free this when
                                 * deleting structure). */
    XColor *darkColorPtr;       /* Color for darker areas (must
                                 * free when deleting structure). */
    Pixmap shadow;              /* Stipple pattern to use for drawing
                                 * lighter-shadow-ed areas.  Only used on
                                 * monochrome displays;  on color displays
                                 * this is None. */
    GC lightGC;                 /* Used to draw lighter parts of
                                 * the border. */
    GC darkGC;                  /* Used to draw darker parts of the
                                 * border. */
    GC bgGC;                    /* Used (if necessary) to draw areas in
                                 * the background color. */
    Tcl_HashEntry *hashPtr;     /* Entry in borderTable (needed in
                                 * order to delete structure). */
} Border;

/*
 * Hash table to map from a border's values (color, etc.) to a
 * Border structure for those values.
 */

static Tcl_HashTable borderTable;
typedef struct {
    Tk_Uid colorName;           /* Color for border. */
    Colormap colormap;          /* Colormap used for allocating border
                                 * colors. */
    Screen *screen;             /* Screen on which border will be drawn. */
} BorderKey;

/*
 * Maximum intensity for a color:
 */

#define MAX_INTENSITY 65535


static int initialized = 0;     /* 0 means static structures haven't
                                 * been initialized yet. */

/*
 * Forward declarations for procedures defined in this file:
 */

static void             BorderInit _ANSI_ARGS_((void));
static int              Intersect _ANSI_ARGS_((XPoint *a1Ptr, XPoint *a2Ptr,
                            XPoint *b1Ptr, XPoint *b2Ptr, XPoint *iPtr));
static void             ShiftLine _ANSI_ARGS_((XPoint *p1Ptr, XPoint *p2Ptr,
                            int distance, XPoint *p3Ptr));
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_Get3DBorder --
 *
 *      Create a data structure for displaying a 3-D border.
 *
 * Results:
 *      The return value is a token for a data structure
 *      describing a 3-D border.  This token may be passed
 *      to Tk_Draw3DRectangle and Tk_Free3DBorder.  If an
 *      error prevented the border from being created then
 *      NULL is returned and an error message will be left
 *      in interp->result.
 *
 * Side effects:
 *      Data structures, graphics contexts, etc. are allocated.
 *      It is the caller's responsibility to eventually call
 *      Tk_Free3DBorder to release the resources.
 *
 *--------------------------------------------------------------
 */

Tk_3DBorder
Tk_Get3DBorder(interp, tkwin, colormap, colorName)
    Tcl_Interp *interp;         /* Place to store an error message. */
    Tk_Window tkwin;            /* Token for window in which
                                 * border will be drawn. */
    Colormap colormap;          /* Colormap to use for allocating border
                                 * colors.  None means use default colormap
                                 * for screen. */
    Tk_Uid colorName;           /* String giving name of color
                                 * for window background. */
{
    BorderKey key;
    Tcl_HashEntry *hashPtr;
    register Border *borderPtr;
    int new;
    unsigned long light, dark;
    XGCValues gcValues;
    unsigned long mask;

    if (!initialized) {
        BorderInit();
    }

    /*
     * First, check to see if there's already a border that will work
     * for this request.
     */

    key.colorName = colorName;
    if (colormap == None) {
        colormap = Tk_DefaultColormap(Tk_Screen(tkwin));
    }
    key.colormap = colormap;
    key.screen = Tk_Screen(tkwin);

    hashPtr = Tcl_CreateHashEntry(&borderTable, (char *) &key, &new);
    if (!new) {
        borderPtr = (Border *) Tcl_GetHashValue(hashPtr);
        borderPtr->refCount++;
    } else {

        /*
         * No satisfactory border exists yet.  Initialize a new one.
         */
    
        borderPtr = (Border *) ckalloc(sizeof(Border));
        borderPtr->display = Tk_Display(tkwin);
        borderPtr->refCount = 1;
        borderPtr->bgColorPtr = NULL;
        borderPtr->lightColorPtr = NULL;
        borderPtr->darkColorPtr = NULL;
        borderPtr->shadow = None;
        borderPtr->lightGC = None;
        borderPtr->darkGC = None;
        borderPtr->bgGC = None;
        borderPtr->hashPtr = hashPtr;
        Tcl_SetHashValue(hashPtr, borderPtr);
    
        /*
         * Figure out what colors and GC's to use for the light
         * and dark areas and set up the graphics contexts.
         * Monochrome displays get handled differently than
         * color displays.
         */
    
        borderPtr->bgColorPtr = Tk_GetColor(interp, tkwin,
                key.colormap, colorName);
        if (borderPtr->bgColorPtr == NULL) {
            goto error;
        }
        if (Tk_DefaultDepth(Tk_Screen(tkwin)) == 1) {
            /*
             * Monochrome display.
             */
    
            light = borderPtr->bgColorPtr->pixel;
            if (light == WhitePixelOfScreen(Tk_Screen(tkwin))) {
                dark = BlackPixelOfScreen(Tk_Screen(tkwin));
            } else {
                dark = WhitePixelOfScreen(Tk_Screen(tkwin));
            }
            borderPtr->shadow = Tk_GetBitmap(interp, tkwin,
                    Tk_GetUid("gray50"));
            if (borderPtr->shadow == None) {
                goto error;
            }
        } else {
            XColor lightColor, darkColor;
            int tmp;

            /*
             * Color display.  Compute the colors for the illuminated
             * and shaded portions of the border.
             */
    
            tmp = (14*(int)borderPtr->bgColorPtr->red)/10;
            if (tmp > MAX_INTENSITY) {
                tmp = MAX_INTENSITY;
            }
            lightColor.red = tmp;
            tmp = (14*(int)borderPtr->bgColorPtr->green)/10;
            if (tmp > MAX_INTENSITY) {
                tmp = MAX_INTENSITY;
            }
            lightColor.green = tmp;
            tmp = (14*(int)borderPtr->bgColorPtr->blue)/10;
            if (tmp > MAX_INTENSITY) {
                tmp = MAX_INTENSITY;
            }
            lightColor.blue = tmp;
            darkColor.red = (60*(int)borderPtr->bgColorPtr->red)/100;
            darkColor.green = (60*(int)borderPtr->bgColorPtr->green)/100;
            darkColor.blue = (60*(int)borderPtr->bgColorPtr->blue)/100;
            borderPtr->lightColorPtr = Tk_GetColorByValue(interp, tkwin,
                    key.colormap, &lightColor);
            if (borderPtr->lightColorPtr == NULL) {
                goto error;
            }
            borderPtr->darkColorPtr = Tk_GetColorByValue(interp, tkwin,
                    key.colormap, &darkColor);
            if (borderPtr->darkColorPtr == NULL) {
                goto error;
            }
            light = borderPtr->lightColorPtr->pixel;
            dark = borderPtr->darkColorPtr->pixel;
        }
        gcValues.foreground = light;
        gcValues.background = dark;
        mask = GCForeground|GCBackground;
        if (borderPtr->shadow != None) {
            gcValues.stipple = borderPtr->shadow;
            gcValues.fill_style = FillOpaqueStippled;
            mask |= GCStipple|GCFillStyle;
        }
        borderPtr->lightGC = Tk_GetGC(tkwin, mask, &gcValues);
        gcValues.foreground = dark;
        gcValues.background = light;
        borderPtr->darkGC = Tk_GetGC(tkwin, GCForeground|GCBackground,
                &gcValues);
        gcValues.foreground = borderPtr->bgColorPtr->pixel;
        borderPtr->bgGC = Tk_GetGC(tkwin, GCForeground, &gcValues);
    }
    return (Tk_3DBorder) borderPtr;

    error:
    Tk_Free3DBorder((Tk_3DBorder) borderPtr);
    return NULL;
}
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_Draw3DRectangle --
 *
 *      Draw a 3-D border at a given place in a given window.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      A 3-D border will be drawn in the indicated drawable.
 *      The outside edges of the border will be determined by x,
 *      y, width, and height.  The inside edges of the border
 *      will be determined by the borderWidth argument.
 *
 *--------------------------------------------------------------
 */

void
Tk_Draw3DRectangle(display, drawable, border, x, y, width, height,
        borderWidth, relief)
    Display *display;           /* X display in which to draw. */
    Drawable drawable;          /* X window or pixmap in which to draw. */
    Tk_3DBorder border;         /* Token for border to draw. */
    int x, y, width, height;    /* Outside area of region in
                                 * which border will be drawn. */
    int borderWidth;            /* Desired width for border, in
                                 * pixels. */
    int relief;                 /* Should be either TK_RELIEF_RAISED
                                 * or TK_RELIEF_SUNKEN;  indicates
                                 * position of interior of window relative
                                 * to exterior. */
{
    register Border *borderPtr = (Border *) border;
    GC top, bottom;
    XPoint points[7];

    if ((width < 2*borderWidth) || (height < 2*borderWidth)) {
        return;
    }

    if (relief == TK_RELIEF_RAISED) {
        top = borderPtr->lightGC;
        bottom = borderPtr->darkGC;
    } else if (relief == TK_RELIEF_SUNKEN) {
        top = borderPtr->darkGC;
        bottom = borderPtr->lightGC;
    } else {
        top = bottom = borderPtr->bgGC;
    }
    XFillRectangle(display, drawable, bottom, x, y+height-borderWidth,

            (unsigned int) width, (unsigned int) borderWidth);
    XFillRectangle(display, drawable, bottom, x+width-borderWidth, y,
            (unsigned int) borderWidth, (unsigned int) height);
    points[0].x = points[1].x = points[6].x = x;
    points[0].y = points[6].y = y + height;
    points[1].y = points[2].y = y;
    points[2].x = x + width;
    points[3].x = x + width - borderWidth;
    points[3].y = points[4].y = y + borderWidth;
    points[4].x = points[5].x = x + borderWidth;
    points[5].y = y + height - borderWidth;
    XFillPolygon(display, drawable, top, points, 7, Nonconvex,
            CoordModeOrigin);
}
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_NameOf3DBorder --
 *
 *      Given a border, return a textual string identifying the
 *      border's color.
 *
 * Results:
 *      The return value is the string that was used to create
 *      the border.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

char *
Tk_NameOf3DBorder(border)
    Tk_3DBorder border;         /* Token for border. */
{
    Border *borderPtr = (Border *) border;

    return ((BorderKey *) borderPtr->hashPtr->key.words)->colorName;
}
\f
/*
 *--------------------------------------------------------------------
 *
 * Tk_3DBorderColor --
 *
 *      Given a 3D border, return the X color used for the "flat"
 *      surfaces.
 *
 * Results:
 *      Returns the color used drawing flat surfaces with the border.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------------
 */
XColor *
Tk_3DBorderColor(border)
    Tk_3DBorder border;
{
    return(((Border *) border)->bgColorPtr);
}
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_Free3DBorder --
 *
 *      This procedure is called when a 3D border is no longer
 *      needed.  It frees the resources associated with the
 *      border.  After this call, the caller should never again
 *      use the "border" token.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Resources are freed.
 *
 *--------------------------------------------------------------
 */

void
Tk_Free3DBorder(border)
    Tk_3DBorder border;         /* Token for border to be released. */
{
    register Border *borderPtr = (Border *) border;

    borderPtr->refCount--;
    if (borderPtr->refCount == 0) {
        if (borderPtr->bgColorPtr != NULL) {
            Tk_FreeColor(borderPtr->bgColorPtr);
        }
        if (borderPtr->lightColorPtr != NULL) {
            Tk_FreeColor(borderPtr->lightColorPtr);
        }
        if (borderPtr->darkColorPtr != NULL) {
            Tk_FreeColor(borderPtr->darkColorPtr);
        }
        if (borderPtr->shadow != None) {
            Tk_FreeBitmap(borderPtr->shadow);
        }
        if (borderPtr->lightGC != None) {
            Tk_FreeGC(borderPtr->lightGC);
        }
        if (borderPtr->darkGC != None) {
            Tk_FreeGC(borderPtr->darkGC);
        }
        if (borderPtr->bgGC != None) {
            Tk_FreeGC(borderPtr->bgGC);
        }
        Tcl_DeleteHashEntry(borderPtr->hashPtr);
        ckfree((char *) borderPtr);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * Tk_SetBackgroundFromBorder --
 *
 *      Change the background of a window to one appropriate for a given
 *      3-D border.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Tkwin's background gets modified.
 *
 *----------------------------------------------------------------------
 */

void
Tk_SetBackgroundFromBorder(tkwin, border)
    Tk_Window tkwin;            /* Window whose background is to be set. */
    Tk_3DBorder border;         /* Token for border. */
{
    register Border *borderPtr = (Border *) border;

    Tk_SetWindowBackground(tkwin, borderPtr->bgColorPtr->pixel);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * Tk_GetRelief --
 *
 *      Parse a relief description and return the corresponding
 *      relief value, or an error.
 *
 * Results:
 *      A standard Tcl return value.  If all goes well then
 *      *reliefPtr is filled in with one of the values
 *      TK_RELIEF_RAISED, TK_RELIEF_FLAT, or TK_RELIEF_SUNKEN.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
Tk_GetRelief(interp, name, reliefPtr)
    Tcl_Interp *interp;         /* For error messages. */
    char *name;                 /* Name of a relief type. */
    int *reliefPtr;             /* Where to store converted relief. */
{
    char c;
    int length;

    c = name[0];
    length = strlen(name);
    if ((c == 'f') && (strncmp(name, "flat", length) == 0)) {
        *reliefPtr = TK_RELIEF_FLAT;
    } else if ((c == 'r') && (strncmp(name, "raised", length) == 0)) {
        *reliefPtr = TK_RELIEF_RAISED;
    } else if ((c == 's') && (strncmp(name, "sunken", length) == 0)) {
        *reliefPtr = TK_RELIEF_SUNKEN;
    } else {
        sprintf(interp->result, "bad relief type \"%.50s\":  must be %s",
                name, "flat, raised, or sunken");
        return TCL_ERROR;
    }
    return TCL_OK;
}
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_NameOfRelief --
 *
 *      Given a relief value, produce a string describing that
 *      relief value.
 *
 * Results:
 *      The return value is a static string that is equivalent
 *      to relief.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

char *
Tk_NameOfRelief(relief)
    int relief;         /* One of TK_RELIEF_FLAT, TK_RELIEF_RAISED,
                         * or TK_RELIEF_SUNKEN. */
{
    if (relief == TK_RELIEF_FLAT) {
        return "flat";
    } else if (relief == TK_RELIEF_SUNKEN) {
        return "sunken";
    } else if (relief == TK_RELIEF_RAISED) {
        return "raised";
    } else {
        return "unknown relief";
    }
}
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_Draw3DPolygon --
 *
 *      Draw a border with 3-D appearance around the edge of a
 *      given polygon.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Information is drawn in "drawable" in the form of a
 *      3-D border borderWidth units width wide on the left
 *      of the trajectory given by pointPtr and numPoints (or
 *      -borderWidth units wide on the right side, if borderWidth
 *      is negative.
 *
 *--------------------------------------------------------------
 */

void
Tk_Draw3DPolygon(display, drawable, border, pointPtr, numPoints,
        borderWidth, leftRelief)
    Display *display;           /* X display in which to draw polygon. */
    Drawable drawable;          /* X window or pixmap in which to draw. */
    Tk_3DBorder border;         /* Token for border to draw. */
    XPoint *pointPtr;           /* Array of points describing
                                 * polygon.  All points must be
                                 * absolute (CoordModeOrigin). */
    int numPoints;              /* Number of points at *pointPtr. */
    int borderWidth;            /* Width of border, measured in
                                 * pixels to the left of the polygon's
                                 * trajectory.   May be negative. */
    int leftRelief;             /* TK_RELIEF_RAISED or
                                 * TK_RELIEF_SUNKEN: indicates how
                                 * stuff to left of trajectory looks
                                 * relative to stuff on right. */
{
    XPoint poly[4], b1, b2, newB1, newB2;
    XPoint perp, c, shift1, shift2;     /* Used for handling parallel lines. */
    register XPoint *p1Ptr, *p2Ptr;
    Border *borderPtr = (Border *) border;
    GC gc;
    int i, lightOnLeft, dx, dy, parallel, pointsSeen;

    /*
     * If the polygon is already closed, drop the last point from it
     * (we'll close it automatically).
     */

    p1Ptr = &pointPtr[numPoints-1];
    p2Ptr = &pointPtr[0];
    if ((p1Ptr->x == p2Ptr->x) && (p1Ptr->y == p2Ptr->y)) {
        numPoints--;
    }

    /*
     * The loop below is executed once for each vertex in the polgon.
     * At the beginning of each iteration things look like this:
     *
     *          poly[1]       /
     *             *        /
     *             |      /
     *             b1   * poly[0] (pointPtr[i-1])
     *             |    |
     *             |    |
     *             |    |
     *             |    |
     *             |    |
     *             |    | *p1Ptr            *p2Ptr
     *             b2   *--------------------*
     *             |
     *             |
     *             x-------------------------
     *
     * The job of this iteration is to do the following:
     * (a) Compute x (the border corner corresponding to
     *     pointPtr[i]) and put it in poly[2].  As part of
     *     this, compute a new b1 and b2 value for the next
     *     side of the polygon.
     * (b) Put pointPtr[i] into poly[3].
     * (c) Draw the polygon given by poly[0..3].
     * (d) Advance poly[0], poly[1], b1, and b2 for the
     *     next side of the polygon.
     */

    /*
     * The above situation doesn't first come into existence until
     * two points have been processed;  the first two points are
     * used to "prime the pump", so some parts of the processing
     * are ommitted for these points.  The variable "pointsSeen"
     * keeps track of the priming process;  it has to be separate
     * from i in order to be able to ignore duplicate points in the
     * polygon.
     */

    pointsSeen = 0;
    for (i = -2, p1Ptr = &pointPtr[numPoints-2], p2Ptr = p1Ptr+1;
            i < numPoints; i++, p1Ptr = p2Ptr, p2Ptr++) {
        if ((i == -1) || (i == numPoints-1)) {
            p2Ptr = pointPtr;
        }
        if ((p2Ptr->x == p1Ptr->x) && (p2Ptr->y == p1Ptr->y)) {
            /*
             * Ignore duplicate points (they'd cause core dumps in
             * ShiftLine calls below).
             */
            continue;
        }
        ShiftLine(p1Ptr, p2Ptr, borderWidth, &newB1);
        newB2.x = newB1.x + (p2Ptr->x - p1Ptr->x);
        newB2.y = newB1.y + (p2Ptr->y - p1Ptr->y);
        poly[3] = *p1Ptr;
        parallel = 0;
        if (pointsSeen >= 1) {
            parallel = Intersect(&newB1, &newB2, &b1, &b2, &poly[2]);

            /*
             * If two consecutive segments of the polygon are parallel,
             * then things get more complex.  Consider the following
             * diagram:
             *
             * poly[1]
             *    *----b1-----------b2------a
             *                                \
             *                                  \
             *         *---------*----------*    b
             *        poly[0]  *p2Ptr   *p1Ptr  /
             *                                /
             *              --*--------*----c
             *              newB1    newB2
             *
             * Instead of using x and *p1Ptr for poly[2] and poly[3], as
             * in the original diagram, use a and b as above.  Then instead
             * of using x and *p1Ptr for the new poly[0] and poly[1], use
             * b and c as above.
             *
             * Do the computation in three stages:
             * 1. Compute a point "perp" such that the line p1Ptr-perp
             *    is perpendicular to p1Ptr-p2Ptr.
             * 2. Compute the points a and c by intersecting the lines
             *    b1-b2 and newB1-newB2 with p1Ptr-perp.
             * 3. Compute b by shifting p1Ptr-perp to the right and
             *    intersecting it with p1Ptr-p2Ptr.
             */

            if (parallel) {
                perp.x = p1Ptr->x + (p2Ptr->y - p1Ptr->y);
                perp.y = p1Ptr->y - (p2Ptr->x - p1Ptr->x);
                (void) Intersect(p1Ptr, &perp, &b1, &b2, &poly[2]);
                (void) Intersect(p1Ptr, &perp, &newB1, &newB2, &c);
                ShiftLine(p1Ptr, &perp, borderWidth, &shift1);
                shift2.x = shift1.x + (perp.x - p1Ptr->x);
                shift2.y = shift1.y + (perp.y - p1Ptr->y);
                (void) Intersect(p1Ptr, p2Ptr, &shift1, &shift2, &poly[3]);
            }
        }
        if (pointsSeen >= 2) {
            dx = poly[3].x - poly[0].x;
            dy = poly[3].y - poly[0].y;
            if (dx > 0) {
                lightOnLeft = (dy <= dx);
            } else {
                lightOnLeft = (dy < dx);
            }
            if (lightOnLeft ^ (leftRelief == TK_RELIEF_RAISED)) {
                gc = borderPtr->lightGC;
            } else {
                gc = borderPtr->darkGC;
            }
            XFillPolygon(display, drawable, gc, poly, 4, Convex,
                    CoordModeOrigin);
        }
        b1.x = newB1.x;
        b1.y = newB1.y;
        b2.x = newB2.x;
        b2.y = newB2.y;
        poly[0].x = poly[3].x;
        poly[0].y = poly[3].y;
        if (parallel) {
            poly[1].x = c.x;
            poly[1].y = c.y;
        } else if (pointsSeen >= 1) {
            poly[1].x = poly[2].x;
            poly[1].y = poly[2].y;
        }
        pointsSeen++;
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * Tk_Fill3DRectangle --
 *
 *      Fill a rectangular area, supplying a 3D border if desired.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Information gets drawn on the screen.
 *
 *----------------------------------------------------------------------
 */

void
Tk_Fill3DRectangle(display, drawable, border, x, y, width,
        height, borderWidth, relief)
    Display *display;           /* X display in which to draw rectangle. */
    Drawable drawable;          /* X window or pixmap in which to draw. */
    Tk_3DBorder border;         /* Token for border to draw. */
    int x, y, width, height;    /* Outside area of rectangular region. */
    int borderWidth;            /* Desired width for border, in
                                 * pixels. Border will be *inside* region. */
    int relief;                 /* Indicates 3D effect: TK_RELIEF_FLAT,
                                 * TK_RELIEF_RAISED, or TK_RELIEF_SUNKEN. */
{
    register Border *borderPtr = (Border *) border;

    XFillRectangle(display, drawable, borderPtr->bgGC,
            x, y, (unsigned int) width, (unsigned int) height);
    if (relief != TK_RELIEF_FLAT) {
        Tk_Draw3DRectangle(display, drawable, border, x, y, width,
                height, borderWidth, relief);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * Tk_Fill3DPolygon --
 *
 *      Fill a polygonal area, supplying a 3D border if desired.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Information gets drawn on the screen.
 *
 *----------------------------------------------------------------------
 */

void
Tk_Fill3DPolygon(display, drawable, border, pointPtr, numPoints,
        borderWidth, leftRelief)
    Display *display;           /* X display in which to draw polygon. */
    Drawable drawable;          /* X window or pixmap in which to draw. */
    Tk_3DBorder border;         /* Token for border to draw. */
    XPoint *pointPtr;           /* Array of points describing
                                 * polygon.  All points must be
                                 * absolute (CoordModeOrigin). */
    int numPoints;              /* Number of points at *pointPtr. */
    int borderWidth;            /* Width of border, measured in
                                 * pixels to the left of the polygon's
                                 * trajectory.   May be negative. */
    int leftRelief;                     /* Indicates 3D effect of left side of
                                 * trajectory relative to right:
                                 * TK_RELIEF_FLAT, TK_RELIEF_RAISED,
                                 * or TK_RELIEF_SUNKEN. */
{
    register Border *borderPtr = (Border *) border;

    XFillPolygon(display, drawable, borderPtr->bgGC,
            pointPtr, numPoints, Complex, CoordModeOrigin);
    if (leftRelief != TK_RELIEF_FLAT) {
        Tk_Draw3DPolygon(display, drawable, border, pointPtr, numPoints,
                borderWidth, leftRelief);
    }
}
\f
/*
 *--------------------------------------------------------------
 *
 * BorderInit --
 *
 *      Initialize the structures used for border management.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Read the code.
 *
 *-------------------------------------------------------------
 */

static void
BorderInit()
{
    initialized = 1;
    Tcl_InitHashTable(&borderTable, sizeof(BorderKey)/sizeof(int));
}
\f
/*
 *--------------------------------------------------------------
 *
 * ShiftLine --
 *
 *      Given two points on a line, compute a point on a
 *      new line that is parallel to the given line and
 *      a given distance away from it.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

static void
ShiftLine(p1Ptr, p2Ptr, distance, p3Ptr)
    XPoint *p1Ptr;              /* First point on line. */
    XPoint *p2Ptr;              /* Second point on line. */
    int distance;               /* New line is to be this many
                                 * units to the left of original
                                 * line, when looking from p1 to
                                 * p2.  May be negative. */
    XPoint *p3Ptr;              /* Store coords of point on new
                                 * line here. */
{
    int dx, dy, dxNeg, dyNeg;

    /*
     * The table below is used for a quick approximation in
     * computing the new point.  An index into the table
     * is 128 times the slope of the original line (the slope
     * must always be between 0 and 1).  The value of the table
     * entry is 128 times the amount to displace the new line
     * in y for each unit of perpendicular distance.  In other
     * words, the table maps from the tangent of an angle to
     * the inverse of its cosine.  If the slope of the original
     * line is greater than 1, then the displacement is done in
     * x rather than in y.
     */

    static int shiftTable[129];

    /*
     * Initialize the table if this is the first time it is
     * used.
     */

    if (shiftTable[0] == 0) {
        int i;
        double tangent, cosine;

        for (i = 0; i <= 128; i++) {
            tangent = i/128.0;
            cosine = 128/cos(atan(tangent)) + .5;
            shiftTable[i] = cosine;
        }
    }

    *p3Ptr = *p1Ptr;
    dx = p2Ptr->x - p1Ptr->x;
    dy = p2Ptr->y - p1Ptr->y;
    if (dy < 0) {
        dyNeg = 1;
        dy = -dy;
    } else {
        dyNeg = 0;
    }
    if (dx < 0) {
        dxNeg = 1;
        dx = -dx;
    } else {
        dxNeg = 0;
    }
    if (dy <= dx) {
        dy = ((distance * shiftTable[(dy<<7)/dx]) + 64) >> 7;
        if (!dxNeg) {
            dy = -dy;
        }
        p3Ptr->y += dy;
    } else {
        dx = ((distance * shiftTable[(dx<<7)/dy]) + 64) >> 7;
        if (dyNeg) {
            dx = -dx;
        }
        p3Ptr->x += dx;
    }
}
\f
/*
 *--------------------------------------------------------------
 *
 * Intersect --
 *
 *      Find the intersection point between two lines.
 *
 * Results:
 *      Under normal conditions 0 is returned and the point
 *      at *iPtr is filled in with the intersection between
 *      the two lines.  If the two lines are parallel, then
 *      -1 is returned and *iPtr isn't modified.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

static int
Intersect(a1Ptr, a2Ptr, b1Ptr, b2Ptr, iPtr)
    XPoint *a1Ptr;              /* First point of first line. */
    XPoint *a2Ptr;              /* Second point of first line. */
    XPoint *b1Ptr;              /* First point of second line. */
    XPoint *b2Ptr;              /* Second point of second line. */
    XPoint *iPtr;               /* Filled in with intersection point. */
{
    int dxadyb, dxbdya, dxadxb, dyadyb, p, q;

    /*
     * The code below is just a straightforward manipulation of two
     * equations of the form y = (x-x1)*(y2-y1)/(x2-x1) + y1 to solve
     * for the x-coordinate of intersection, then the y-coordinate.
     */

    dxadyb = (a2Ptr->x - a1Ptr->x)*(b2Ptr->y - b1Ptr->y);
    dxbdya = (b2Ptr->x - b1Ptr->x)*(a2Ptr->y - a1Ptr->y);
    dxadxb = (a2Ptr->x - a1Ptr->x)*(b2Ptr->x - b1Ptr->x);
    dyadyb = (a2Ptr->y - a1Ptr->y)*(b2Ptr->y - b1Ptr->y);

    if (dxadyb == dxbdya) {
        return -1;
    }
    p = (a1Ptr->x*dxbdya - b1Ptr->x*dxadyb + (b1Ptr->y - a1Ptr->y)*dxadxb);
    q = dxbdya - dxadyb;
    if (q < 0) {
        p = -p;
        q = -q;
    }
    if (p < 0) {
        iPtr->x = - ((-p + q/2)/q);
    } else {
        iPtr->x = (p + q/2)/q;
    }
    p = (a1Ptr->y*dxadyb - b1Ptr->y*dxbdya + (b1Ptr->x - a1Ptr->x)*dyadyb);
    q = dxadyb - dxbdya;
    if (q < 0) {
        p = -p;
        q = -q;
    }
    if (p < 0) {
        iPtr->y = - ((-p + q/2)/q);
    } else {
        iPtr->y = (p + q/2)/q;
    }
    return 0;
}