/* 
 * tkImgBmap.c --
 *
 *	This procedure implements images of type "bitmap" for Tk.
 *
 * Copyright (c) 1994 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 * Copyright (c) 1999 by Scriptics Corporation.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tkImgBmap.c,v 1.1.1.1 1999/06/25 17:35:57 damon Exp $
 */

#include "tkInt.h"
#include "tkPort.h"

/*
 * The following data structure represents the master for a bitmap
 * image:
 */

typedef struct BitmapMaster {
    Tk_ImageMaster tkMaster;	/* Tk's token for image master.  NULL means
				 * the image is being deleted. */
    Tcl_Interp *interp;		/* Interpreter for application that is
				 * using image. */
    Tcl_Command imageCmd;	/* Token for image command (used to delete
				 * it when the image goes away).  NULL means
				 * the image command has already been
				 * deleted. */
    int width, height;		/* Dimensions of image. */
    char *data;			/* Data comprising bitmap (suitable for
				 * input to XCreateBitmapFromData).   May
				 * be NULL if no data.  Malloc'ed. */
    char *maskData;		/* Data for bitmap's mask (suitable for
				 * input to XCreateBitmapFromData).
				 * Malloc'ed. */
    Tk_Uid fgUid;		/* Value of -foreground option (malloc'ed). */
    Tk_Uid bgUid;		/* Value of -background option (malloc'ed). */
    char *fileString;		/* Value of -file option (malloc'ed). */
    char *dataString;		/* Value of -data option (malloc'ed). */
    char *maskFileString;	/* Value of -maskfile option (malloc'ed). */
    char *maskDataString;	/* Value of -maskdata option (malloc'ed). */
    struct BitmapInstance *instancePtr;
				/* First in list of all instances associated
				 * with this master. */
} BitmapMaster;

/*
 * The following data structure represents all of the instances of an
 * image that lie within a particular window:
 */

typedef struct BitmapInstance {
    int refCount;		/* Number of instances that share this
				 * data structure. */
    BitmapMaster *masterPtr;	/* Pointer to master for image. */
    Tk_Window tkwin;		/* Window in which the instances will be
				 * displayed. */
    XColor *fg;			/* Foreground color for displaying image. */
    XColor *bg;			/* Background color for displaying image. */
    Pixmap bitmap;		/* The bitmap to display. */
    Pixmap mask;		/* Mask: only display bitmap pixels where
				 * there are 1's here. */
    GC gc;			/* Graphics context for displaying bitmap.
				 * None means there was an error while
				 * setting up the instance, so it cannot
				 * be displayed. */
    struct BitmapInstance *nextPtr;
				/* Next in list of all instance structures
				 * associated with masterPtr (NULL means
				 * end of list). */
} BitmapInstance;

/*
 * The type record for bitmap images:
 */

static int		GetByte _ANSI_ARGS_((Tcl_Channel chan));
static int		ImgBmapCreate _ANSI_ARGS_((Tcl_Interp *interp,
			    char *name, int argc, char **argv,
			    Tk_ImageType *typePtr, Tk_ImageMaster master,
			    ClientData *clientDataPtr));
static ClientData	ImgBmapGet _ANSI_ARGS_((Tk_Window tkwin,
			    ClientData clientData));
static void		ImgBmapDisplay _ANSI_ARGS_((ClientData clientData,
			    Display *display, Drawable drawable, 
			    int imageX, int imageY, int width, int height,
			    int drawableX, int drawableY));
static void		ImgBmapFree _ANSI_ARGS_((ClientData clientData,
			    Display *display));
static void		ImgBmapDelete _ANSI_ARGS_((ClientData clientData));

Tk_ImageType tkBitmapImageType = {
    "bitmap",			/* name */
    ImgBmapCreate,		/* createProc */
    ImgBmapGet,			/* getProc */
    ImgBmapDisplay,		/* displayProc */
    ImgBmapFree,		/* freeProc */
    ImgBmapDelete,		/* deleteProc */
    (Tk_ImageType *) NULL	/* nextPtr */
};

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

static Tk_ConfigSpec configSpecs[] = {
    {TK_CONFIG_UID, "-background", (char *) NULL, (char *) NULL,
	"", Tk_Offset(BitmapMaster, bgUid), 0},
    {TK_CONFIG_STRING, "-data", (char *) NULL, (char *) NULL,
	(char *) NULL, Tk_Offset(BitmapMaster, dataString), TK_CONFIG_NULL_OK},
    {TK_CONFIG_STRING, "-file", (char *) NULL, (char *) NULL,
	(char *) NULL, Tk_Offset(BitmapMaster, fileString), TK_CONFIG_NULL_OK},
    {TK_CONFIG_UID, "-foreground", (char *) NULL, (char *) NULL,
	"#000000", Tk_Offset(BitmapMaster, fgUid), 0},
    {TK_CONFIG_STRING, "-maskdata", (char *) NULL, (char *) NULL,
	(char *) NULL, Tk_Offset(BitmapMaster, maskDataString),
	TK_CONFIG_NULL_OK},
    {TK_CONFIG_STRING, "-maskfile", (char *) NULL, (char *) NULL,
	(char *) NULL, Tk_Offset(BitmapMaster, maskFileString),
	TK_CONFIG_NULL_OK},
    {TK_CONFIG_END, (char *) NULL, (char *) NULL, (char *) NULL,
	(char *) NULL, 0, 0}
};

/*
 * The following data structure is used to describe the state of
 * parsing a bitmap file or string.  It is used for communication
 * between TkGetBitmapData and NextBitmapWord.
 */

#define MAX_WORD_LENGTH 100
typedef struct ParseInfo {
    char *string;		/* Next character of string data for bitmap,
				 * or NULL if bitmap is being read from
				 * file. */
    Tcl_Channel chan;		/* File containing bitmap data, or NULL
				 * if no file. */
    char word[MAX_WORD_LENGTH+1];
				/* Current word of bitmap data, NULL
				 * terminated. */
    int wordLength;		/* Number of non-NULL bytes in word. */
} ParseInfo;

/*
 * Prototypes for procedures used only locally in this file:
 */

static int		ImgBmapCmd _ANSI_ARGS_((ClientData clientData,
			    Tcl_Interp *interp, int argc, char **argv));
static void		ImgBmapCmdDeletedProc _ANSI_ARGS_((
			    ClientData clientData));
static void		ImgBmapConfigureInstance _ANSI_ARGS_((
			    BitmapInstance *instancePtr));
static int		ImgBmapConfigureMaster _ANSI_ARGS_((
			    BitmapMaster *masterPtr, int argc, char **argv,
			    int flags));
static int		NextBitmapWord _ANSI_ARGS_((ParseInfo *parseInfoPtr));

/*
 *----------------------------------------------------------------------
 *
 * ImgBmapCreate --
 *
 *	This procedure is called by the Tk image code to create "test"
 *	images.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	The data structure for a new image is allocated.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
static int
ImgBmapCreate(interp, name, argc, argv, typePtr, master, clientDataPtr)
    Tcl_Interp *interp;		/* Interpreter for application containing
				 * image. */
    char *name;			/* Name to use for image. */
    int argc;			/* Number of arguments. */
    char **argv;		/* Argument strings for options (doesn't
				 * include image name or type). */
    Tk_ImageType *typePtr;	/* Pointer to our type record (not used). */
    Tk_ImageMaster master;	/* Token for image, to be used by us in
				 * later callbacks. */
    ClientData *clientDataPtr;	/* Store manager's token for image here;
				 * it will be returned in later callbacks. */
{
    BitmapMaster *masterPtr;

    masterPtr = (BitmapMaster *) ckalloc(sizeof(BitmapMaster));
    masterPtr->tkMaster = master;
    masterPtr->interp = interp;
    masterPtr->imageCmd = Tcl_CreateCommand(interp, name, ImgBmapCmd,
	    (ClientData) masterPtr, ImgBmapCmdDeletedProc);
    masterPtr->width = masterPtr->height = 0;
    masterPtr->data = NULL;
    masterPtr->maskData = NULL;
    masterPtr->fgUid = NULL;
    masterPtr->bgUid = NULL;
    masterPtr->fileString = NULL;
    masterPtr->dataString = NULL;
    masterPtr->maskFileString = NULL;
    masterPtr->maskDataString = NULL;
    masterPtr->instancePtr = NULL;
    if (ImgBmapConfigureMaster(masterPtr, argc, argv, 0) != TCL_OK) {
	ImgBmapDelete((ClientData) masterPtr);
	return TCL_ERROR;
    }
    *clientDataPtr = (ClientData) masterPtr;
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ImgBmapConfigureMaster --
 *
 *	This procedure is called when a bitmap image is created or
 *	reconfigured.  It process configuration options and resets
 *	any instances of the image.
 *
 * Results:
 *	A standard Tcl return value.  If TCL_ERROR is returned then
 *	an error message is left in the masterPtr->interp's result.
 *
 * Side effects:
 *	Existing instances of the image will be redisplayed to match
 *	the new configuration options.
 *
 *----------------------------------------------------------------------
 */

static int
ImgBmapConfigureMaster(masterPtr, argc, argv, flags)
    BitmapMaster *masterPtr;	/* Pointer to data structure describing
				 * overall bitmap image to (reconfigure). */
    int argc;			/* Number of entries in argv. */
    char **argv;		/* Pairs of configuration options for image. */
    int flags;			/* Flags to pass to Tk_ConfigureWidget,
				 * such as TK_CONFIG_ARGV_ONLY. */
{
    BitmapInstance *instancePtr;
    int maskWidth, maskHeight, dummy1, dummy2;

    if (Tk_ConfigureWidget(masterPtr->interp, Tk_MainWindow(masterPtr->interp),
	    configSpecs, argc, argv, (char *) masterPtr, flags)
	    != TCL_OK) {
	return TCL_ERROR;
    }

    /*
     * Parse the bitmap and/or mask to create binary data.  Make sure that
     * the bitmap and mask have the same dimensions.
     */

    if (masterPtr->data != NULL) {
	ckfree(masterPtr->data);
	masterPtr->data = NULL;
    }
    if ((masterPtr->fileString != NULL) || (masterPtr->dataString != NULL)) {
	masterPtr->data = TkGetBitmapData(masterPtr->interp,
		masterPtr->dataString, masterPtr->fileString,
		&masterPtr->width, &masterPtr->height, &dummy1, &dummy2);
	if (masterPtr->data == NULL) {
	    return TCL_ERROR;
	}
    }
    if (masterPtr->maskData != NULL) {
	ckfree(masterPtr->maskData);
	masterPtr->maskData = NULL;
    }
    if ((masterPtr->maskFileString != NULL)
	    || (masterPtr->maskDataString != NULL)) {
	if (masterPtr->data == NULL) {
	    Tcl_SetResult(masterPtr->interp, "can't have mask without bitmap",
		    TCL_STATIC);
	    return TCL_ERROR;
	}
	masterPtr->maskData = TkGetBitmapData(masterPtr->interp,
		masterPtr->maskDataString, masterPtr->maskFileString,
		&maskWidth, &maskHeight, &dummy1, &dummy2);
	if (masterPtr->maskData == NULL) {
	    return TCL_ERROR;
	}
	if ((maskWidth != masterPtr->width)
		|| (maskHeight != masterPtr->height)) {
	    ckfree(masterPtr->maskData);
	    masterPtr->maskData = NULL;
	    Tcl_SetResult(masterPtr->interp,
		    "bitmap and mask have different sizes", TCL_STATIC);
	    return TCL_ERROR;
	}
    }

    /*
     * Cycle through all of the instances of this image, regenerating
     * the information for each instance.  Then force the image to be
     * redisplayed everywhere that it is used.
     */

    for (instancePtr = masterPtr->instancePtr; instancePtr != NULL;
	    instancePtr = instancePtr->nextPtr) {
	ImgBmapConfigureInstance(instancePtr);
    }
    Tk_ImageChanged(masterPtr->tkMaster, 0, 0, masterPtr->width,
	    masterPtr->height, masterPtr->width, masterPtr->height);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ImgBmapConfigureInstance --
 *
 *	This procedure is called to create displaying information for
 *	a bitmap image instance based on the configuration information
 *	in the master.  It is invoked both when new instances are
 *	created and when the master is reconfigured.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Generates errors via Tcl_BackgroundError if there are problems
 *	in setting up the instance.
 *
 *----------------------------------------------------------------------
 */

static void
ImgBmapConfigureInstance(instancePtr)
    BitmapInstance *instancePtr;	/* Instance to reconfigure. */
{
    BitmapMaster *masterPtr = instancePtr->masterPtr;
    XColor *colorPtr;
    XGCValues gcValues;
    GC gc;
    unsigned int mask;
    Pixmap oldMask;

    /*
     * For each of the options in masterPtr, translate the string
     * form into an internal form appropriate for instancePtr.
     */

    if (*masterPtr->bgUid != 0) {
	colorPtr = Tk_GetColor(masterPtr->interp, instancePtr->tkwin,
		masterPtr->bgUid);
	if (colorPtr == NULL) {
	    goto error;
	}
    } else {
	colorPtr = NULL;
    }
    if (instancePtr->bg != NULL) {
	Tk_FreeColor(instancePtr->bg);
    }
    instancePtr->bg = colorPtr;

    colorPtr = Tk_GetColor(masterPtr->interp, instancePtr->tkwin,
	    masterPtr->fgUid);
    if (colorPtr == NULL) {
	goto error;
    }
    if (instancePtr->fg != NULL) {
	Tk_FreeColor(instancePtr->fg);
    }
    instancePtr->fg = colorPtr;

    if (instancePtr->bitmap != None) {
	Tk_FreePixmap(Tk_Display(instancePtr->tkwin), instancePtr->bitmap);
	instancePtr->bitmap = None;
    }
    if (masterPtr->data != NULL) {
	instancePtr->bitmap = XCreateBitmapFromData(
		Tk_Display(instancePtr->tkwin),
		RootWindowOfScreen(Tk_Screen(instancePtr->tkwin)),
		masterPtr->data, (unsigned) masterPtr->width,
		(unsigned) masterPtr->height);
    }

    /*
     * Careful:  We have to allocate a new mask Pixmap before deleting
     * the old one.  Otherwise, The XID allocator will always return
     * the same XID for the new Pixmap as was used for the old Pixmap.
     * And that will prevent the mask from changing in the GC below.
     */
    oldMask = instancePtr->mask;
    instancePtr->mask = None;
    if (masterPtr->maskData != NULL) {
	instancePtr->mask = XCreateBitmapFromData(
		Tk_Display(instancePtr->tkwin),
		RootWindowOfScreen(Tk_Screen(instancePtr->tkwin)),
		masterPtr->maskData, (unsigned) masterPtr->width,
		(unsigned) masterPtr->height);
    }
    if (oldMask != None) {
      Tk_FreePixmap(Tk_Display(instancePtr->tkwin), oldMask);
    }

    if (masterPtr->data != NULL) {
	gcValues.foreground = instancePtr->fg->pixel;
	gcValues.graphics_exposures = False;
	mask = GCForeground|GCGraphicsExposures;
	if (instancePtr->bg != NULL) {
	    gcValues.background = instancePtr->bg->pixel;
	    mask |= GCBackground;
	    if (instancePtr->mask != None) {
		gcValues.clip_mask = instancePtr->mask;
		mask |= GCClipMask;
	    }
	} else {
	    gcValues.clip_mask = instancePtr->bitmap;
	    mask |= GCClipMask;
	}
	gc = Tk_GetGC(instancePtr->tkwin, mask, &gcValues);
    } else {
	gc = None;
    }
    if (instancePtr->gc != None) {
	Tk_FreeGC(Tk_Display(instancePtr->tkwin), instancePtr->gc);
    }
    instancePtr->gc = gc;
    return;

    error:
    /*
     * An error occurred: clear the graphics context in the instance to
     * make it clear that this instance cannot be displayed.  Then report
     * the error.
     */

    if (instancePtr->gc != None) {
	Tk_FreeGC(Tk_Display(instancePtr->tkwin), instancePtr->gc);
    }
    instancePtr->gc = None;
    Tcl_AddErrorInfo(masterPtr->interp, "\n    (while configuring image \"");
    Tcl_AddErrorInfo(masterPtr->interp, Tk_NameOfImage(masterPtr->tkMaster));
    Tcl_AddErrorInfo(masterPtr->interp, "\")");
    Tcl_BackgroundError(masterPtr->interp);
}

/*
 *----------------------------------------------------------------------
 *
 * TkGetBitmapData --
 *
 *	Given a file name or ASCII string, this procedure parses the
 *	file or string contents to produce binary data for a bitmap.
 *
 * Results:
 *	If the bitmap description was parsed successfully then the
 *	return value is a malloc-ed array containing the bitmap data.
 *	The dimensions of the data are stored in *widthPtr and
 *	*heightPtr.  *hotXPtr and *hotYPtr are set to the bitmap
 *	hotspot if one is defined, otherwise they are set to -1, -1.
 *	If an error occurred, NULL is returned and an error message is
 *	left in the interp's result.
 *
 * Side effects:
 *	A bitmap is created.
 *
 *----------------------------------------------------------------------
 */

char *
TkGetBitmapData(interp, string, fileName, widthPtr, heightPtr,
	hotXPtr, hotYPtr)
    Tcl_Interp *interp;			/* For reporting errors, or NULL. */
    char *string;			/* String describing bitmap.  May
					 * be NULL. */
    char *fileName;			/* Name of file containing bitmap
					 * description.  Used only if string
					 * is NULL.  Must not be NULL if
					 * string is NULL. */
    int *widthPtr, *heightPtr;		/* Dimensions of bitmap get returned
					 * here. */
    int *hotXPtr, *hotYPtr;		/* Position of hot spot or -1,-1. */
{
    int width, height, numBytes, hotX, hotY;
    char *p, *end, *expandedFileName;
    ParseInfo pi;
    char *data = NULL;
    Tcl_DString buffer;

    pi.string = string;
    if (string == NULL) {
        if ((interp != NULL) && Tcl_IsSafe(interp)) {
            Tcl_AppendResult(interp, "can't get bitmap data from a file in a",
                    " safe interpreter", (char *) NULL);
            return NULL;
        }
	expandedFileName = Tcl_TranslateFileName(interp, fileName, &buffer);
	if (expandedFileName == NULL) {
	    return NULL;
	}
	pi.chan = Tcl_OpenFileChannel(interp, expandedFileName, "r", 0);
	Tcl_DStringFree(&buffer);
	if (pi.chan == NULL) {
	    if (interp != NULL) {
		Tcl_ResetResult(interp);
		Tcl_AppendResult(interp, "couldn't read bitmap file \"",
			fileName, "\": ", Tcl_PosixError(interp),
			(char *) NULL);
	    }
	    return NULL;
	}
	
        if (Tcl_SetChannelOption(interp, pi.chan, "-translation", "binary")
		!= TCL_OK) {
            return NULL;
        }
        if (Tcl_SetChannelOption(interp, pi.chan, "-encoding", "binary")
		!= TCL_OK) {
            return NULL;
        }
    } else {
	pi.chan = NULL;
    }

    /*
     * Parse the lines that define the dimensions of the bitmap,
     * plus the first line that defines the bitmap data (it declares
     * the name of a data variable but doesn't include any actual
     * data).  These lines look something like the following:
     *
     *		#define foo_width 16
     *		#define foo_height 16
     *		#define foo_x_hot 3
     *		#define foo_y_hot 3
     *		static char foo_bits[] = {
     *
     * The x_hot and y_hot lines may or may not be present.  It's
     * important to check for "char" in the last line, in order to
     * reject old X10-style bitmaps that used shorts.
     */

    width = 0;
    height = 0;
    hotX = -1;
    hotY = -1;
    while (1) {
	if (NextBitmapWord(&pi) != TCL_OK) {
	    goto error;
	}
	if ((pi.wordLength >= 6) && (pi.word[pi.wordLength-6] == '_')
		&& (strcmp(pi.word+pi.wordLength-6, "_width") == 0)) {
	    if (NextBitmapWord(&pi) != TCL_OK) {
		goto error;
	    }
	    width = strtol(pi.word, &end, 0);
	    if ((end == pi.word) || (*end != 0)) {
		goto error;
	    }
	} else if ((pi.wordLength >= 7) && (pi.word[pi.wordLength-7] == '_')
		&& (strcmp(pi.word+pi.wordLength-7, "_height") == 0)) {
	    if (NextBitmapWord(&pi) != TCL_OK) {
		goto error;
	    }
	    height = strtol(pi.word, &end, 0);
	    if ((end == pi.word) || (*end != 0)) {
		goto error;
	    }
	} else if ((pi.wordLength >= 6) && (pi.word[pi.wordLength-6] == '_')
		&& (strcmp(pi.word+pi.wordLength-6, "_x_hot") == 0)) {
	    if (NextBitmapWord(&pi) != TCL_OK) {
		goto error;
	    }
	    hotX = strtol(pi.word, &end, 0);
	    if ((end == pi.word) || (*end != 0)) {
		goto error;
	    }
	} else if ((pi.wordLength >= 6) && (pi.word[pi.wordLength-6] == '_')
		&& (strcmp(pi.word+pi.wordLength-6, "_y_hot") == 0)) {
	    if (NextBitmapWord(&pi) != TCL_OK) {
		goto error;
	    }
	    hotY = strtol(pi.word, &end, 0);
	    if ((end == pi.word) || (*end != 0)) {
		goto error;
	    }
	} else if ((pi.word[0] == 'c') && (strcmp(pi.word, "char") == 0)) {
	    while (1) {
		if (NextBitmapWord(&pi) != TCL_OK) {
		    goto error;
		}
		if ((pi.word[0] == '{') && (pi.word[1] == 0)) {
		    goto getData;
		}
	    }
	} else if ((pi.word[0] == '{') && (pi.word[1] == 0)) {
	    if (interp != NULL) {
		Tcl_AppendResult(interp, "format error in bitmap data; ",
			"looks like it's an obsolete X10 bitmap file",
			(char *) NULL);
	    }
	    goto errorCleanup;
	}
    }

    /*
     * Now we've read everything but the data.  Allocate an array
     * and read in the data.
     */

    getData:
    if ((width <= 0) || (height <= 0)) {
	goto error;
    }
    numBytes = ((width+7)/8) * height;
    data = (char *) ckalloc((unsigned) numBytes);
    for (p = data; numBytes > 0; p++, numBytes--) {
	if (NextBitmapWord(&pi) != TCL_OK) {
	    goto error;
	}
	*p = (char) strtol(pi.word, &end, 0);
	if (end == pi.word) {
	    goto error;
	}
    }

    /*
     * All done.  Clean up and return.
     */

    if (pi.chan != NULL) {
	Tcl_Close(NULL, pi.chan);
    }
    *widthPtr = width;
    *heightPtr = height;
    *hotXPtr = hotX;
    *hotYPtr = hotY;
    return data;

    error:
    if (interp != NULL) {
	Tcl_SetResult(interp, "format error in bitmap data", TCL_STATIC);
    }
    
    errorCleanup:
    if (data != NULL) {
	ckfree(data);
    }
    if (pi.chan != NULL) {
	Tcl_Close(NULL, pi.chan);
    }
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * NextBitmapWord --
 *
 *	This procedure retrieves the next word of information (stuff
 *	between commas or white space) from a bitmap description.
 *
 * Results:
 *	Returns TCL_OK if all went well.  In this case the next word,
 *	and its length, will be availble in *parseInfoPtr.  If the end
 *	of the bitmap description was reached then TCL_ERROR is returned.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
NextBitmapWord(parseInfoPtr)
    ParseInfo *parseInfoPtr;		/* Describes what we're reading
					 * and where we are in it. */
{
    char *src, *dst;
    int c;

    parseInfoPtr->wordLength = 0;
    dst = parseInfoPtr->word;
    if (parseInfoPtr->string != NULL) {
	for (src = parseInfoPtr->string; isspace(UCHAR(*src)) || (*src == ',');
		src++) {
	    if (*src == 0) {
		return TCL_ERROR;
	    }
	}
	for ( ; !isspace(UCHAR(*src)) && (*src != ',') && (*src != 0); src++) {
	    *dst = *src;
	    dst++;
	    parseInfoPtr->wordLength++;
	    if (parseInfoPtr->wordLength > MAX_WORD_LENGTH) {
		return TCL_ERROR;
	    }
	}
	parseInfoPtr->string = src;
    } else {
	for (c = GetByte(parseInfoPtr->chan); isspace(UCHAR(c)) || (c == ',');
		c = GetByte(parseInfoPtr->chan)) {
	    if (c == EOF) {
		return TCL_ERROR;
	    }
	}
	for ( ; !isspace(UCHAR(c)) && (c != ',') && (c != EOF);
		c = GetByte(parseInfoPtr->chan)) {
	    *dst = c;
	    dst++;
	    parseInfoPtr->wordLength++;
	    if (parseInfoPtr->wordLength > MAX_WORD_LENGTH) {
		return TCL_ERROR;
	    }
	}
    }
    if (parseInfoPtr->wordLength == 0) {
	return TCL_ERROR;
    }
    parseInfoPtr->word[parseInfoPtr->wordLength] = 0;
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * ImgBmapCmd --
 *
 *	This procedure is invoked to process the Tcl command
 *	that corresponds to an image managed by this module.
 *	See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *--------------------------------------------------------------
 */

static int
ImgBmapCmd(clientData, interp, argc, argv)
    ClientData clientData;	/* Information about the image master. */
    Tcl_Interp *interp;		/* Current interpreter. */
    int argc;			/* Number of arguments. */
    char **argv;		/* Argument strings. */
{
    BitmapMaster *masterPtr = (BitmapMaster *) clientData;
    int c, code;
    size_t length;

    if (argc < 2) {
	Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
		" option ?arg arg ...?\"", (char *) NULL);
	return TCL_ERROR;
    }
    c = argv[1][0];
    length = strlen(argv[1]);
    if ((c == 'c') && (strncmp(argv[1], "cget", length) == 0)
	    && (length >= 2)) {
	if (argc != 3) {
	    Tcl_AppendResult(interp, "wrong # args: should be \"",
		    argv[0], " cget option\"",
		    (char *) NULL);
	    return TCL_ERROR;
	}
	return Tk_ConfigureValue(interp, Tk_MainWindow(interp), configSpecs,
		(char *) masterPtr, argv[2], 0);
    } else if ((c == 'c') && (strncmp(argv[1], "configure", length) == 0)
	    && (length >= 2)) {
	if (argc == 2) {
	    code = Tk_ConfigureInfo(interp, Tk_MainWindow(interp),
		    configSpecs, (char *) masterPtr, (char *) NULL, 0);
	} else if (argc == 3) {
	    code = Tk_ConfigureInfo(interp, Tk_MainWindow(interp),
		    configSpecs, (char *) masterPtr, argv[2], 0);
	} else {
	    code = ImgBmapConfigureMaster(masterPtr, argc-2, argv+2,
		    TK_CONFIG_ARGV_ONLY);
	}
	return code;
    } else {
	Tcl_AppendResult(interp, "bad option \"", argv[1],
		"\": must be cget or configure", (char *) NULL);
	return TCL_ERROR;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ImgBmapGet --
 *
 *	This procedure is called for each use of a bitmap image in a
 *	widget.
 *
 * Results:
 *	The return value is a token for the instance, which is passed
 *	back to us in calls to ImgBmapDisplay and ImgBmapFree.
 *
 * Side effects:
 *	A data structure is set up for the instance (or, an existing
 *	instance is re-used for the new one).
 *
 *----------------------------------------------------------------------
 */

static ClientData
ImgBmapGet(tkwin, masterData)
    Tk_Window tkwin;		/* Window in which the instance will be
				 * used. */
    ClientData masterData;	/* Pointer to our master structure for the
				 * image. */
{
    BitmapMaster *masterPtr = (BitmapMaster *) masterData;
    BitmapInstance *instancePtr;

    /*
     * See if there is already an instance for this window.  If so
     * then just re-use it.
     */

    for (instancePtr = masterPtr->instancePtr; instancePtr != NULL;
	    instancePtr = instancePtr->nextPtr) {
	if (instancePtr->tkwin == tkwin) {
	    instancePtr->refCount++;
	    return (ClientData) instancePtr;
	}
    }

    /*
     * The image isn't already in use in this window.  Make a new
     * instance of the image.
     */

    instancePtr = (BitmapInstance *) ckalloc(sizeof(BitmapInstance));
    instancePtr->refCount = 1;
    instancePtr->masterPtr = masterPtr;
    instancePtr->tkwin = tkwin;
    instancePtr->fg = NULL;
    instancePtr->bg = NULL;
    instancePtr->bitmap = None;
    instancePtr->mask = None;
    instancePtr->gc = None;
    instancePtr->nextPtr = masterPtr->instancePtr;
    masterPtr->instancePtr = instancePtr;
    ImgBmapConfigureInstance(instancePtr);

    /*
     * If this is the first instance, must set the size of the image.
     */

    if (instancePtr->nextPtr == NULL) {
	Tk_ImageChanged(masterPtr->tkMaster, 0, 0, 0, 0, masterPtr->width,
		masterPtr->height);
    }

    return (ClientData) instancePtr;
}

/*
 *----------------------------------------------------------------------
 *
 * ImgBmapDisplay --
 *
 *	This procedure is invoked to draw a bitmap image.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	A portion of the image gets rendered in a pixmap or window.
 *
 *----------------------------------------------------------------------
 */

static void
ImgBmapDisplay(clientData, display, drawable, imageX, imageY, width,
	height, drawableX, drawableY)
    ClientData clientData;	/* Pointer to BitmapInstance structure for
				 * for instance to be displayed. */
    Display *display;		/* Display on which to draw image. */
    Drawable drawable;		/* Pixmap or window in which to draw image. */
    int imageX, imageY;		/* Upper-left corner of region within image
				 * to draw. */
    int width, height;		/* Dimensions of region within image to draw. */
    int drawableX, drawableY;	/* Coordinates within drawable that
				 * correspond to imageX and imageY. */
{
    BitmapInstance *instancePtr = (BitmapInstance *) clientData;
    int masking;

    /*
     * If there's no graphics context, it means that an error occurred
     * while creating the image instance so it can't be displayed.
     */

    if (instancePtr->gc == None) {
	return;
    }

    /*
     * If masking is in effect, must modify the mask origin within
     * the graphics context to line up with the image's origin.
     * Then draw the image and reset the clip origin, if there's
     * a mask.
     */

    masking = (instancePtr->mask != None) || (instancePtr->bg == NULL);
    if (masking) {
	XSetClipOrigin(display, instancePtr->gc, drawableX - imageX,
		drawableY - imageY);
    }
    XCopyPlane(display, instancePtr->bitmap, drawable, instancePtr->gc,
	    imageX, imageY, (unsigned) width, (unsigned) height,
	    drawableX, drawableY, 1);
    if (masking) {
	XSetClipOrigin(display, instancePtr->gc, 0, 0);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ImgBmapFree --
 *
 *	This procedure is called when a widget ceases to use a
 *	particular instance of an image.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Internal data structures get cleaned up.
 *
 *----------------------------------------------------------------------
 */

static void
ImgBmapFree(clientData, display)
    ClientData clientData;	/* Pointer to BitmapInstance structure for
				 * for instance to be displayed. */
    Display *display;		/* Display containing window that used image. */
{
    BitmapInstance *instancePtr = (BitmapInstance *) clientData;
    BitmapInstance *prevPtr;

    instancePtr->refCount--;
    if (instancePtr->refCount > 0) {
	return;
    }

    /*
     * There are no more uses of the image within this widget.  Free
     * the instance structure.
     */

    if (instancePtr->fg != NULL) {
	Tk_FreeColor(instancePtr->fg);
    }
    if (instancePtr->bg != NULL) {
	Tk_FreeColor(instancePtr->bg);
    }
    if (instancePtr->bitmap != None) {
	Tk_FreePixmap(display, instancePtr->bitmap);
    }
    if (instancePtr->mask != None) {
	Tk_FreePixmap(display, instancePtr->mask);
    }
    if (instancePtr->gc != None) {
	Tk_FreeGC(display, instancePtr->gc);
    }
    if (instancePtr->masterPtr->instancePtr == instancePtr) {
	instancePtr->masterPtr->instancePtr = instancePtr->nextPtr;
    } else {
	for (prevPtr = instancePtr->masterPtr->instancePtr;
		prevPtr->nextPtr != instancePtr; prevPtr = prevPtr->nextPtr) {
	    /* Empty loop body */
	}
	prevPtr->nextPtr = instancePtr->nextPtr;
    }
    ckfree((char *) instancePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * ImgBmapDelete --
 *
 *	This procedure is called by the image code to delete the
 *	master structure for an image.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Resources associated with the image get freed.
 *
 *----------------------------------------------------------------------
 */

static void
ImgBmapDelete(masterData)
    ClientData masterData;	/* Pointer to BitmapMaster structure for
				 * image.  Must not have any more instances. */
{
    BitmapMaster *masterPtr = (BitmapMaster *) masterData;

    if (masterPtr->instancePtr != NULL) {
	panic("tried to delete bitmap image when instances still exist");
    }
    masterPtr->tkMaster = NULL;
    if (masterPtr->imageCmd != NULL) {
	Tcl_DeleteCommandFromToken(masterPtr->interp, masterPtr->imageCmd);
    }
    if (masterPtr->data != NULL) {
	ckfree(masterPtr->data);
    }
    if (masterPtr->maskData != NULL) {
	ckfree(masterPtr->maskData);
    }
    Tk_FreeOptions(configSpecs, (char *) masterPtr, (Display *) NULL, 0);
    ckfree((char *) masterPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * ImgBmapCmdDeletedProc --
 *
 *	This procedure is invoked when the image command for an image
 *	is deleted.  It deletes the image.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The image is deleted.
 *
 *----------------------------------------------------------------------
 */

static void
ImgBmapCmdDeletedProc(clientData)
    ClientData clientData;	/* Pointer to BitmapMaster structure for
				 * image. */
{
    BitmapMaster *masterPtr = (BitmapMaster *) clientData;

    masterPtr->imageCmd = NULL;
    if (masterPtr->tkMaster != NULL) {
	Tk_DeleteImage(masterPtr->interp, Tk_NameOfImage(masterPtr->tkMaster));
    }
}

/*
 *----------------------------------------------------------------------
 *
 * GetByte --
 *
 *	Get the next byte from the open channel.
 *
 * Results:
 *	The next byte or EOF.
 *
 * Side effects:
 *	We read from the channel.
 *
 *----------------------------------------------------------------------
 */

static int
GetByte(chan)
    Tcl_Channel chan;	/* The channel we read from. */
{
    char buffer;
    int size;

    size = Tcl_Read(chan, &buffer, 1);
    if (size <= 0) {
	return EOF;
    } else {
	return buffer;
    }
}
