path: root/generic/tkCanvBmap.c

/* 
 * tkCanvBmap.c --
 *
 *	This file implements bitmap items for canvas widgets.
 *
 * Copyright (c) 1992-1994 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tkCanvBmap.c,v 1.1.4.2 1998/09/30 02:16:42 stanton Exp $
 */

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

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

typedef struct BitmapItem  {
    Tk_Item header;		/* Generic stuff that's the same for all
				 * types.  MUST BE FIRST IN STRUCTURE. */
    double x, y;		/* Coordinates of positioning point for
				 * bitmap. */
    Tk_Anchor anchor;		/* Where to anchor bitmap relative to
				 * (x,y). */
    Pixmap bitmap;		/* Bitmap to display in window. */
    XColor *fgColor;		/* Foreground color to use for bitmap. */
    XColor *bgColor;		/* Background color to use for bitmap. */
    GC gc;			/* Graphics context to use for drawing
				 * bitmap on screen. */
} BitmapItem;

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

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

static Tk_ConfigSpec configSpecs[] = {
    {TK_CONFIG_ANCHOR, "-anchor", (char *) NULL, (char *) NULL,
	"center", Tk_Offset(BitmapItem, anchor), TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_COLOR, "-background", (char *) NULL, (char *) NULL,
	(char *) NULL, Tk_Offset(BitmapItem, bgColor), TK_CONFIG_NULL_OK},
    {TK_CONFIG_BITMAP, "-bitmap", (char *) NULL, (char *) NULL,
	(char *) NULL, Tk_Offset(BitmapItem, bitmap), TK_CONFIG_NULL_OK},
    {TK_CONFIG_COLOR, "-foreground", (char *) NULL, (char *) NULL,
	"black", Tk_Offset(BitmapItem, fgColor), 0},
    {TK_CONFIG_CUSTOM, "-tags", (char *) NULL, (char *) NULL,
	(char *) NULL, 0, TK_CONFIG_NULL_OK, &tagsOption},
    {TK_CONFIG_END, (char *) NULL, (char *) NULL, (char *) NULL,
	(char *) NULL, 0, 0}
};

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

static int		BitmapCoords _ANSI_ARGS_((Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr, int argc,
			    char **argv));
static int		BitmapToArea _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, double *rectPtr));
static double		BitmapToPoint _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, double *coordPtr));
static int		BitmapToPostscript _ANSI_ARGS_((Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr, int prepass));
static void		ComputeBitmapBbox _ANSI_ARGS_((Tk_Canvas canvas,
			    BitmapItem *bmapPtr));
static int		ConfigureBitmap _ANSI_ARGS_((Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr, int argc,
			    char **argv, int flags));
static int		CreateBitmap _ANSI_ARGS_((Tcl_Interp *interp,
			    Tk_Canvas canvas, struct Tk_Item *itemPtr,
			    int argc, char **argv));
static void		DeleteBitmap _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, Display *display));
static void		DisplayBitmap _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, Display *display, Drawable dst,
			    int x, int y, int width, int height));
static void		ScaleBitmap _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, double originX, double originY,
			    double scaleX, double scaleY));
static void		TranslateBitmap _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, double deltaX, double deltaY));

/*
 * The structures below defines the bitmap item type in terms of
 * procedures that can be invoked by generic item code.
 */

Tk_ItemType tkBitmapType = {
    "bitmap",				/* name */
    sizeof(BitmapItem),			/* itemSize */
    CreateBitmap,			/* createProc */
    configSpecs,			/* configSpecs */
    ConfigureBitmap,			/* configureProc */
    BitmapCoords,			/* coordProc */
    DeleteBitmap,			/* deleteProc */
    DisplayBitmap,			/* displayProc */
    0,					/* alwaysRedraw */
    BitmapToPoint,			/* pointProc */
    BitmapToArea,			/* areaProc */
    BitmapToPostscript,			/* postscriptProc */
    ScaleBitmap,			/* scaleProc */
    TranslateBitmap,			/* 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 */
};

/*
 *--------------------------------------------------------------
 *
 * CreateBitmap --
 *
 *	This procedure is invoked to create a new bitmap
 *	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 bitmap item is created.
 *
 *--------------------------------------------------------------
 */

static int
CreateBitmap(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 rectangle. */
{
    BitmapItem *bmapPtr = (BitmapItem *) itemPtr;

    if (argc < 2) {
	Tcl_AppendResult(interp, "wrong # args: should be \"",
		Tk_PathName(Tk_CanvasTkwin(canvas)), " create ",
		itemPtr->typePtr->name, " x y ?options?\"",
		(char *) NULL);
	return TCL_ERROR;
    }

    /*
     * Initialize item's record.
     */

    bmapPtr->anchor = TK_ANCHOR_CENTER;
    bmapPtr->bitmap = None;
    bmapPtr->fgColor = NULL;
    bmapPtr->bgColor = NULL;
    bmapPtr->gc = None;

    /*
     * Process the arguments to fill in the item record.
     */

    if ((Tk_CanvasGetCoord(interp, canvas, argv[0], &bmapPtr->x) != TCL_OK)
	    || (Tk_CanvasGetCoord(interp, canvas, argv[1], &bmapPtr->y)
		!= TCL_OK)) {
	return TCL_ERROR;
    }

    if (ConfigureBitmap(interp, canvas, itemPtr, argc-2, argv+2, 0) != TCL_OK) {
	DeleteBitmap(canvas, itemPtr, Tk_Display(Tk_CanvasTkwin(canvas)));
	return TCL_ERROR;
    }
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * BitmapCoords --
 *
 *	This procedure is invoked to process the "coords" widget
 *	command on bitmap items.  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
BitmapCoords(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, ... */
{
    BitmapItem *bmapPtr = (BitmapItem *) itemPtr;
    char x[TCL_DOUBLE_SPACE], y[TCL_DOUBLE_SPACE];

    if (argc == 0) {
	Tcl_PrintDouble(interp, bmapPtr->x, x);
	Tcl_PrintDouble(interp, bmapPtr->y, y);
	Tcl_AppendResult(interp, x, " ", y, (char *) NULL);
    } else if (argc == 2) {
	if ((Tk_CanvasGetCoord(interp, canvas, argv[0], &bmapPtr->x) != TCL_OK)
		|| (Tk_CanvasGetCoord(interp, canvas, argv[1], &bmapPtr->y)
		    != TCL_OK)) {
	    return TCL_ERROR;
	}
	ComputeBitmapBbox(canvas, bmapPtr);
    } else {
	char buf[64 + TCL_INTEGER_SPACE];

	sprintf(buf, "wrong # coordinates: expected 0 or 2, got %d", argc);
	Tcl_SetResult(interp, buf, TCL_VOLATILE);
	return TCL_ERROR;
    }
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * ConfigureBitmap --
 *
 *	This procedure is invoked to configure various aspects
 *	of a bitmap item, such as its anchor position.
 *
 * 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 may be set for itemPtr.
 *
 *--------------------------------------------------------------
 */

static int
ConfigureBitmap(interp, canvas, itemPtr, argc, argv, flags)
    Tcl_Interp *interp;		/* Used for error reporting. */
    Tk_Canvas canvas;		/* Canvas containing itemPtr. */
    Tk_Item *itemPtr;		/* Bitmap 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. */
{
    BitmapItem *bmapPtr = (BitmapItem *) itemPtr;
    XGCValues gcValues;
    GC newGC;
    Tk_Window tkwin;
    unsigned long mask;

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

    /*
     * A few of the options require additional processing, such as those
     * that determine the graphics context.
     */

    gcValues.foreground = bmapPtr->fgColor->pixel;
    mask = GCForeground;
    if (bmapPtr->bgColor != NULL) {
	gcValues.background = bmapPtr->bgColor->pixel;
	mask |= GCBackground;
    } else {
	gcValues.clip_mask = bmapPtr->bitmap;
	mask |= GCClipMask;
    }
    newGC = Tk_GetGC(tkwin, mask, &gcValues);
    if (bmapPtr->gc != None) {
	Tk_FreeGC(Tk_Display(tkwin), bmapPtr->gc);
    }
    bmapPtr->gc = newGC;

    ComputeBitmapBbox(canvas, bmapPtr);

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

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

    if (bmapPtr->bitmap != None) {
	Tk_FreeBitmap(display, bmapPtr->bitmap);
    }
    if (bmapPtr->fgColor != NULL) {
	Tk_FreeColor(bmapPtr->fgColor);
    }
    if (bmapPtr->bgColor != NULL) {
	Tk_FreeColor(bmapPtr->bgColor);
    }
    if (bmapPtr->gc != NULL) {
	Tk_FreeGC(display, bmapPtr->gc);
    }
}

/*
 *--------------------------------------------------------------
 *
 * ComputeBitmapBbox --
 *
 *	This procedure is invoked to compute the bounding box of
 *	all the pixels that may be drawn as part of a bitmap item.
 *	This procedure is where the child bitmap's placement is
 *	computed.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The fields x1, y1, x2, and y2 are updated in the header
 *	for itemPtr.
 *
 *--------------------------------------------------------------
 */

	/* ARGSUSED */
static void
ComputeBitmapBbox(canvas, bmapPtr)
    Tk_Canvas canvas;			/* Canvas that contains item. */
    BitmapItem *bmapPtr;		/* Item whose bbox is to be
					 * recomputed. */
{
    int width, height;
    int x, y;

    x = (int) (bmapPtr->x + ((bmapPtr->x >= 0) ? 0.5 : - 0.5));
    y = (int) (bmapPtr->y + ((bmapPtr->y >= 0) ? 0.5 : - 0.5));

    if (bmapPtr->bitmap == None) {
	bmapPtr->header.x1 = bmapPtr->header.x2 = x;
	bmapPtr->header.y1 = bmapPtr->header.y2 = y;
	return;
    }

    /*
     * Compute location and size of bitmap, using anchor information.
     */

    Tk_SizeOfBitmap(Tk_Display(Tk_CanvasTkwin(canvas)), bmapPtr->bitmap,
	    &width, &height);
    switch (bmapPtr->anchor) {
	case TK_ANCHOR_N:
	    x -= width/2;
	    break;
	case TK_ANCHOR_NE:
	    x -= width;
	    break;
	case TK_ANCHOR_E:
	    x -= width;
	    y -= height/2;
	    break;
	case TK_ANCHOR_SE:
	    x -= width;
	    y -= height;
	    break;
	case TK_ANCHOR_S:
	    x -= width/2;
	    y -= height;
	    break;
	case TK_ANCHOR_SW:
	    y -= height;
	    break;
	case TK_ANCHOR_W:
	    y -= height/2;
	    break;
	case TK_ANCHOR_NW:
	    break;
	case TK_ANCHOR_CENTER:
	    x -= width/2;
	    y -= height/2;
	    break;
    }

    /*
     * Store the information in the item header.
     */

    bmapPtr->header.x1 = x;
    bmapPtr->header.y1 = y;
    bmapPtr->header.x2 = x + width;
    bmapPtr->header.y2 = y + height;
}

/*
 *--------------------------------------------------------------
 *
 * DisplayBitmap --
 *
 *	This procedure is invoked to draw a bitmap item in a given
 *	drawable.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	ItemPtr is drawn in drawable using the transformation
 *	information in canvas.
 *
 *--------------------------------------------------------------
 */

static void
DisplayBitmap(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). */
{
    BitmapItem *bmapPtr = (BitmapItem *) itemPtr;
    int bmapX, bmapY, bmapWidth, bmapHeight;
    short drawableX, drawableY;

    /*
     * If the area being displayed doesn't cover the whole bitmap,
     * then only redisplay the part of the bitmap that needs
     * redisplay.
     */

    if (bmapPtr->bitmap != None) {
	if (x > bmapPtr->header.x1) {
	    bmapX = x - bmapPtr->header.x1;
	    bmapWidth = bmapPtr->header.x2 - x;
	} else {
	    bmapX = 0;
	    if ((x+width) < bmapPtr->header.x2) {
		bmapWidth = x + width - bmapPtr->header.x1;
	    } else {
		bmapWidth = bmapPtr->header.x2 - bmapPtr->header.x1;
	    }
	}
	if (y > bmapPtr->header.y1) {
	    bmapY = y - bmapPtr->header.y1;
	    bmapHeight = bmapPtr->header.y2 - y;
	} else {
	    bmapY = 0;
	    if ((y+height) < bmapPtr->header.y2) {
		bmapHeight = y + height - bmapPtr->header.y1;
	    } else {
		bmapHeight = bmapPtr->header.y2 - bmapPtr->header.y1;
	    }
	}
	Tk_CanvasDrawableCoords(canvas,
		(double) (bmapPtr->header.x1 + bmapX),
		(double) (bmapPtr->header.y1 + bmapY),
		&drawableX, &drawableY);

	/*
	 * Must modify the mask origin within the graphics context
	 * to line up with the bitmap's origin (in order to make
	 * bitmaps with "-background {}" work right).
	 */
 
	XSetClipOrigin(display, bmapPtr->gc, drawableX - bmapX,
		drawableY - bmapY);
	XCopyPlane(display, bmapPtr->bitmap, drawable,
		bmapPtr->gc, bmapX, bmapY, (unsigned int) bmapWidth,
		(unsigned int) bmapHeight, drawableX, drawableY, 1);
    }
}

/*
 *--------------------------------------------------------------
 *
 * BitmapToPoint --
 *
 *	Computes the distance from a given point to a given
 *	rectangle, 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 bitmap.  If the
 *	point isn't inside the bitmap then the return value is the
 *	distance from the point to the bitmap.
 *
 * Side effects:
 *	None.
 *
 *--------------------------------------------------------------
 */

	/* ARGSUSED */
static double
BitmapToPoint(canvas, itemPtr, coordPtr)
    Tk_Canvas canvas;		/* Canvas containing item. */
    Tk_Item *itemPtr;		/* Item to check against point. */
    double *coordPtr;		/* Pointer to x and y coordinates. */
{
    BitmapItem *bmapPtr = (BitmapItem *) itemPtr;
    double x1, x2, y1, y2, xDiff, yDiff;

    x1 = bmapPtr->header.x1;
    y1 = bmapPtr->header.y1;
    x2 = bmapPtr->header.x2;
    y2 = bmapPtr->header.y2;

    /*
     * Point is outside rectangle.
     */

    if (coordPtr[0] < x1) {
	xDiff = x1 - coordPtr[0];
    } else if (coordPtr[0] > x2)  {
	xDiff = coordPtr[0] - x2;
    } else {
	xDiff = 0;
    }

    if (coordPtr[1] < y1) {
	yDiff = y1 - coordPtr[1];
    } else if (coordPtr[1] > y2)  {
	yDiff = coordPtr[1] - y2;
    } else {
	yDiff = 0;
    }

    return hypot(xDiff, yDiff);
}

/*
 *--------------------------------------------------------------
 *
 * BitmapToArea --
 *
 *	This procedure is called to determine whether an item
 *	lies entirely inside, entirely outside, or overlapping
 *	a given rectangle.
 *
 * 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
BitmapToArea(canvas, itemPtr, rectPtr)
    Tk_Canvas canvas;		/* Canvas containing item. */
    Tk_Item *itemPtr;		/* Item to check against rectangle. */
    double *rectPtr;		/* Pointer to array of four coordinates
				 * (x1, y1, x2, y2) describing rectangular
				 * area.  */
{
    BitmapItem *bmapPtr = (BitmapItem *) itemPtr;

    if ((rectPtr[2] <= bmapPtr->header.x1)
	    || (rectPtr[0] >= bmapPtr->header.x2)
	    || (rectPtr[3] <= bmapPtr->header.y1)
	    || (rectPtr[1] >= bmapPtr->header.y2)) {
	return -1;
    }
    if ((rectPtr[0] <= bmapPtr->header.x1)
	    && (rectPtr[1] <= bmapPtr->header.y1)
	    && (rectPtr[2] >= bmapPtr->header.x2)
	    && (rectPtr[3] >= bmapPtr->header.y2)) {
	return 1;
    }
    return 0;
}

/*
 *--------------------------------------------------------------
 *
 * ScaleBitmap --
 *
 *	This procedure is invoked to rescale a bitmap item in a
 *	canvas.  It is one of the standard item procedures for
 *	bitmap items, and is invoked by the generic canvas code.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The item 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
ScaleBitmap(canvas, itemPtr, originX, originY, scaleX, scaleY)
    Tk_Canvas canvas;			/* Canvas containing rectangle. */
    Tk_Item *itemPtr;			/* Rectangle to be scaled. */
    double originX, originY;		/* Origin about which to scale item. */
    double scaleX;			/* Amount to scale in X direction. */
    double scaleY;			/* Amount to scale in Y direction. */
{
    BitmapItem *bmapPtr = (BitmapItem *) itemPtr;

    bmapPtr->x = originX + scaleX*(bmapPtr->x - originX);
    bmapPtr->y = originY + scaleY*(bmapPtr->y - originY);
    ComputeBitmapBbox(canvas, bmapPtr);
}

/*
 *--------------------------------------------------------------
 *
 * TranslateBitmap --
 *
 *	This procedure is called to move an item by a given amount.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The position of the item is offset by (xDelta, yDelta), and
 *	the bounding box is updated in the generic part of the item
 *	structure.
 *
 *--------------------------------------------------------------
 */

static void
TranslateBitmap(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. */
{
    BitmapItem *bmapPtr = (BitmapItem *) itemPtr;

    bmapPtr->x += deltaX;
    bmapPtr->y += deltaY;
    ComputeBitmapBbox(canvas, bmapPtr);
}

/*
 *--------------------------------------------------------------
 *
 * BitmapToPostscript --
 *
 *	This procedure is called to generate Postscript for
 *	bitmap 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
BitmapToPostscript(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. */
{
    BitmapItem *bmapPtr = (BitmapItem *) itemPtr;
    double x, y;
    int width, height, rowsAtOnce, rowsThisTime;
    int curRow;
    char buffer[100 + TCL_DOUBLE_SPACE * 2 + TCL_INTEGER_SPACE * 4];

    if (bmapPtr->bitmap == None) {
	return TCL_OK;
    }

    /*
     * Compute the coordinates of the lower-left corner of the bitmap,
     * taking into account the anchor position for the bitmp.
     */

    x = bmapPtr->x;
    y = Tk_CanvasPsY(canvas, bmapPtr->y);
    Tk_SizeOfBitmap(Tk_Display(Tk_CanvasTkwin(canvas)), bmapPtr->bitmap,
	    &width, &height);
    switch (bmapPtr->anchor) {
	case TK_ANCHOR_NW:			y -= height;		break;
	case TK_ANCHOR_N:	x -= width/2.0; y -= height;		break;
	case TK_ANCHOR_NE:	x -= width;	y -= height;		break;
	case TK_ANCHOR_E:	x -= width;	y -= height/2.0;	break;
	case TK_ANCHOR_SE:	x -= width;				break;
	case TK_ANCHOR_S:	x -= width/2.0;				break;
	case TK_ANCHOR_SW:						break;
	case TK_ANCHOR_W:			y -= height/2.0;	break;
	case TK_ANCHOR_CENTER:	x -= width/2.0; y -= height/2.0;	break;
    }

    /*
     * Color the background, if there is one.
     */

    if (bmapPtr->bgColor != NULL) {
	sprintf(buffer,
		"%.15g %.15g moveto %d 0 rlineto 0 %d rlineto %d %s\n",
		x, y, width, height, -width, "0 rlineto closepath");
	Tcl_AppendResult(interp, buffer, (char *) NULL);
	if (Tk_CanvasPsColor(interp, canvas, bmapPtr->bgColor) != TCL_OK) {
	    return TCL_ERROR;
	}
	Tcl_AppendResult(interp, "fill\n", (char *) NULL);
    }

    /*
     * Draw the bitmap, if there is a foreground color.  If the bitmap
     * is very large, then chop it up into multiple bitmaps, each
     * consisting of one or more rows.  This is needed because Postscript
     * can't handle single strings longer than 64 KBytes long.
     */

    if (bmapPtr->fgColor != NULL) {
	if (Tk_CanvasPsColor(interp, canvas, bmapPtr->fgColor) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (width > 60000) {
	    Tcl_ResetResult(interp);
	    Tcl_AppendResult(interp, "can't generate Postscript",
		    " for bitmaps more than 60000 pixels wide",
		    (char *) NULL);
	    return TCL_ERROR;
	}
	rowsAtOnce = 60000/width;
	if (rowsAtOnce < 1) {
	    rowsAtOnce = 1;
	}
	sprintf(buffer, "%.15g %.15g translate\n", x, y+height);
	Tcl_AppendResult(interp, buffer, (char *) NULL);
	for (curRow = 0; curRow < height; curRow += rowsAtOnce) {
	    rowsThisTime = rowsAtOnce;
	    if (rowsThisTime > (height - curRow)) {
		rowsThisTime = height - curRow;
	    }
	    sprintf(buffer, "0 -%.15g translate\n%d %d true matrix {\n",
		    (double) rowsThisTime, width, rowsThisTime);
	    Tcl_AppendResult(interp, buffer, (char *) NULL);
	    if (Tk_CanvasPsBitmap(interp, canvas, bmapPtr->bitmap,
		    0, curRow, width, rowsThisTime) != TCL_OK) {
		return TCL_ERROR;
	    }
	    Tcl_AppendResult(interp, "\n} imagemask\n", (char *) NULL);
	}
    }
    return TCL_OK;
}