path: root/generic/tkCanvText.c

/* 
 * tkCanvText.c --
 *
 *	This file implements text items for canvas widgets.
 *
 * Copyright (c) 1991-1994 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: tkCanvText.c,v 1.5 1999/04/20 22:28:52 rjohnson Exp $
 */

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

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

typedef struct TextItem  {
    Tk_Item header;		/* Generic stuff that's the same for all
				 * types.  MUST BE FIRST IN STRUCTURE. */
    Tk_CanvasTextInfo *textInfoPtr;
				/* Pointer to a structure containing
				 * information about the selection and
				 * insertion cursor.  The structure is owned
				 * by (and shared with) the generic canvas
				 * code. */
    /*
     * Fields that are set by widget commands other than "configure".
     */
     
    double x, y;		/* Positioning point for text. */
    int insertPos;		/* Character index of character just before
				 * which the insertion cursor is displayed. */

    /*
     * Configuration settings that are updated by Tk_ConfigureWidget.
     */

    Tk_Anchor anchor;		/* Where to anchor text relative to (x,y). */
    XColor *color;		/* Color for text. */
    Tk_Font tkfont;		/* Font for drawing text. */
    Tk_Justify justify;		/* Justification mode for text. */
    Pixmap stipple;		/* Stipple bitmap for text, or None. */
    char *text;			/* Text for item (malloc-ed). */
    int width;			/* Width of lines for word-wrap, pixels.
				 * Zero means no word-wrap. */

    /*
     * Fields whose values are derived from the current values of the
     * configuration settings above.
     */

    int numChars;		/* Length of text in characters. */
    int numBytes;		/* Length of text in bytes. */
    Tk_TextLayout textLayout;	/* Cached text layout information. */
    int leftEdge;		/* Pixel location of the left edge of the
				 * text item; where the left border of the
				 * text layout is drawn. */
    int rightEdge;		/* Pixel just to right of right edge of
				 * area of text item.  Used for selecting up
				 * to end of line. */
    GC gc;			/* Graphics context for drawing text. */
    GC selTextGC;		/* Graphics context for selected text. */
    GC cursorOffGC;		/* If not None, this gives a graphics context
				 * to use to draw the insertion cursor when
				 * it's off.  Used if the selection and
				 * insertion cursor colors are the same.  */
} TextItem;

/*
 * 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(TextItem, anchor),
	TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_COLOR, "-fill", (char *) NULL, (char *) NULL,
	"black", Tk_Offset(TextItem, color), TK_CONFIG_NULL_OK},
    {TK_CONFIG_FONT, "-font", (char *) NULL, (char *) NULL,
	DEF_CANVTEXT_FONT, Tk_Offset(TextItem, tkfont), 0},
    {TK_CONFIG_JUSTIFY, "-justify", (char *) NULL, (char *) NULL,
	"left", Tk_Offset(TextItem, justify),
	TK_CONFIG_DONT_SET_DEFAULT},
    {TK_CONFIG_BITMAP, "-stipple", (char *) NULL, (char *) NULL,
	(char *) NULL, Tk_Offset(TextItem, stipple), TK_CONFIG_NULL_OK},
    {TK_CONFIG_CUSTOM, "-tags", (char *) NULL, (char *) NULL,
	(char *) NULL, 0, TK_CONFIG_NULL_OK, &tagsOption},
    {TK_CONFIG_STRING, "-text", (char *) NULL, (char *) NULL,
	"", Tk_Offset(TextItem, text), 0},
    {TK_CONFIG_PIXELS, "-width", (char *) NULL, (char *) NULL,
	"0", Tk_Offset(TextItem, 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		ComputeTextBbox _ANSI_ARGS_((Tk_Canvas canvas,
			    TextItem *textPtr));
static int		ConfigureText _ANSI_ARGS_((Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr, int argc,
			    char **argv, int flags));
static int		CreateText _ANSI_ARGS_((Tcl_Interp *interp,
			    Tk_Canvas canvas, struct Tk_Item *itemPtr,
			    int argc, char **argv));
static void		DeleteText _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, Display *display));
static void		DisplayCanvText _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, Display *display, Drawable dst,
			    int x, int y, int width, int height));
static int		GetSelText _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, int offset, char *buffer,
			    int maxBytes));
static int		GetTextIndex _ANSI_ARGS_((Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr,
			    char *indexString, int *indexPtr));
static void		ScaleText _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, double originX, double originY,
			    double scaleX, double scaleY));
static void		SetTextCursor _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, int index));
static int		TextCoords _ANSI_ARGS_((Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr,
			    int argc, char **argv));
static void		TextDeleteChars _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, int first, int last));
static void		TextInsert _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, int beforeThis, char *string));
static int		TextToArea _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, double *rectPtr));
static double		TextToPoint _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, double *pointPtr));
static int		TextToPostscript _ANSI_ARGS_((Tcl_Interp *interp,
			    Tk_Canvas canvas, Tk_Item *itemPtr, int prepass));
static void		TranslateText _ANSI_ARGS_((Tk_Canvas canvas,
			    Tk_Item *itemPtr, double deltaX, double deltaY));

/*
 * The structures below defines the rectangle and oval item types
 * by means of procedures that can be invoked by generic item code.
 */

Tk_ItemType tkTextType = {
    "text",			/* name */
    sizeof(TextItem),		/* itemSize */
    CreateText,			/* createProc */
    configSpecs,		/* configSpecs */
    ConfigureText,		/* configureProc */
    TextCoords,			/* coordProc */
    DeleteText,			/* deleteProc */
    DisplayCanvText,		/* displayProc */
    0,				/* alwaysRedraw */
    TextToPoint,		/* pointProc */
    TextToArea,			/* areaProc */
    TextToPostscript,		/* postscriptProc */
    ScaleText,			/* scaleProc */
    TranslateText,		/* translateProc */
    GetTextIndex,		/* indexProc */
    SetTextCursor,		/* icursorProc */
    GetSelText,			/* selectionProc */
    TextInsert,			/* insertProc */
    TextDeleteChars,		/* dTextProc */
    (Tk_ItemType *) NULL	/* nextPtr */
};

/*
 *--------------------------------------------------------------
 *
 * CreateText --
 *
 *	This procedure is invoked to create a new text 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 text item is created.
 *
 *--------------------------------------------------------------
 */

static int
CreateText(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. */
{
    TextItem *textPtr = (TextItem *) 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;
    }

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

    textPtr->textInfoPtr = Tk_CanvasGetTextInfo(canvas);

    textPtr->insertPos	= 0;

    textPtr->anchor	= TK_ANCHOR_CENTER;
    textPtr->color	= NULL;
    textPtr->tkfont	= NULL;
    textPtr->justify	= TK_JUSTIFY_LEFT;
    textPtr->stipple	= None;
    textPtr->text	= NULL;
    textPtr->width	= 0;

    textPtr->numChars	= 0;
    textPtr->numBytes	= 0;
    textPtr->textLayout = NULL;
    textPtr->leftEdge	= 0;
    textPtr->rightEdge	= 0;
    textPtr->gc		= None;
    textPtr->selTextGC	= None;
    textPtr->cursorOffGC = None;

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

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

    if (ConfigureText(interp, canvas, itemPtr, argc-2, argv+2, 0) != TCL_OK) {
	DeleteText(canvas, itemPtr, Tk_Display(Tk_CanvasTkwin(canvas)));
	return TCL_ERROR;
    }
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * TextCoords --
 *
 *	This procedure is invoked to process the "coords" widget
 *	command on text 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
TextCoords(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, ... */
{
    TextItem *textPtr = (TextItem *) itemPtr;
    char x[TCL_DOUBLE_SPACE], y[TCL_DOUBLE_SPACE];

    if (argc == 0) {
	Tcl_PrintDouble(interp, textPtr->x, x);
	Tcl_PrintDouble(interp, textPtr->y, y);
	Tcl_AppendResult(interp, x, " ", y, (char *) NULL);
    } else if (argc == 2) {
	if ((Tk_CanvasGetCoord(interp, canvas, argv[0], &textPtr->x) != TCL_OK)
		|| (Tk_CanvasGetCoord(interp, canvas, argv[1],
		    &textPtr->y) != TCL_OK)) {
	    return TCL_ERROR;
	}
	ComputeTextBbox(canvas, textPtr);
    } 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;
}

/*
 *--------------------------------------------------------------
 *
 * ConfigureText --
 *
 *	This procedure is invoked to configure various aspects
 *	of a text item, such as its border and background colors.
 *
 * Results:
 *	A standard Tcl result code.  If an error occurs, then
 *	an error message is left in the interp's result.
 *
 * Side effects:
 *	Configuration information, such as colors and stipple
 *	patterns, may be set for itemPtr.
 *
 *--------------------------------------------------------------
 */

static int
ConfigureText(interp, canvas, itemPtr, argc, argv, flags)
    Tcl_Interp *interp;		/* Interpreter for error reporting. */
    Tk_Canvas canvas;		/* Canvas containing itemPtr. */
    Tk_Item *itemPtr;		/* Rectangle 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. */
{
    TextItem *textPtr = (TextItem *) itemPtr;
    XGCValues gcValues;
    GC newGC, newSelGC;
    unsigned long mask;
    Tk_Window tkwin;
    Tk_CanvasTextInfo *textInfoPtr = textPtr->textInfoPtr;
    XColor *selBgColorPtr;

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

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

    newGC = newSelGC = None;
    if ((textPtr->color != NULL) && (textPtr->tkfont != NULL)) {
	gcValues.foreground = textPtr->color->pixel;
	gcValues.font = Tk_FontId(textPtr->tkfont);
	mask = GCForeground|GCFont;
	if (textPtr->stipple != None) {
	    gcValues.stipple = textPtr->stipple;
	    gcValues.fill_style = FillStippled;
	    mask |= GCForeground|GCStipple|GCFillStyle;
	}
	newGC = Tk_GetGC(tkwin, mask, &gcValues);
	gcValues.foreground = textInfoPtr->selFgColorPtr->pixel;
	newSelGC = Tk_GetGC(tkwin, mask, &gcValues);
    }
    if (textPtr->gc != None) {
	Tk_FreeGC(Tk_Display(tkwin), textPtr->gc);
    }
    textPtr->gc = newGC;
    if (textPtr->selTextGC != None) {
	Tk_FreeGC(Tk_Display(tkwin), textPtr->selTextGC);
    }
    textPtr->selTextGC = newSelGC;

    selBgColorPtr = Tk_3DBorderColor(textInfoPtr->selBorder);
    if (Tk_3DBorderColor(textInfoPtr->insertBorder)->pixel
	    == selBgColorPtr->pixel) {
	if (selBgColorPtr->pixel == BlackPixelOfScreen(Tk_Screen(tkwin))) {
	    gcValues.foreground = WhitePixelOfScreen(Tk_Screen(tkwin));
	} else {
	    gcValues.foreground = BlackPixelOfScreen(Tk_Screen(tkwin));
	}
	newGC = Tk_GetGC(tkwin, GCForeground, &gcValues);
    } else {
	newGC = None;
    }
    if (textPtr->cursorOffGC != None) {
	Tk_FreeGC(Tk_Display(tkwin), textPtr->cursorOffGC);
    }
    textPtr->cursorOffGC = newGC;


    /*
     * If the text was changed, move the selection and insertion indices
     * to keep them inside the item.
     */

    textPtr->numBytes = strlen(textPtr->text);
    textPtr->numChars = Tcl_NumUtfChars(textPtr->text, textPtr->numBytes);
    if (textInfoPtr->selItemPtr == itemPtr) {
	
	if (textInfoPtr->selectFirst >= textPtr->numChars) {
	    textInfoPtr->selItemPtr = NULL;
	} else {
	    if (textInfoPtr->selectLast >= textPtr->numChars) {
		textInfoPtr->selectLast = textPtr->numChars - 1;
	    }
	    if ((textInfoPtr->anchorItemPtr == itemPtr)
		    && (textInfoPtr->selectAnchor >= textPtr->numChars)) {
		textInfoPtr->selectAnchor = textPtr->numChars - 1;
	    }
	}
    }
    if (textPtr->insertPos >= textPtr->numChars) {
	textPtr->insertPos = textPtr->numChars;
    }

    ComputeTextBbox(canvas, textPtr);
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * DeleteText --
 *
 *	This procedure is called to clean up the data structure
 *	associated with a text item.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Resources associated with itemPtr are released.
 *
 *--------------------------------------------------------------
 */

static void
DeleteText(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. */
{
    TextItem *textPtr = (TextItem *) itemPtr;

    if (textPtr->color != NULL) {
	Tk_FreeColor(textPtr->color);
    }
    Tk_FreeFont(textPtr->tkfont);
    if (textPtr->stipple != None) {
	Tk_FreeBitmap(display, textPtr->stipple);
    }
    if (textPtr->text != NULL) {
	ckfree(textPtr->text);
    }

    Tk_FreeTextLayout(textPtr->textLayout);
    if (textPtr->gc != None) {
	Tk_FreeGC(display, textPtr->gc);
    }
    if (textPtr->selTextGC != None) {
	Tk_FreeGC(display, textPtr->selTextGC);
    }
    if (textPtr->cursorOffGC != None) {
	Tk_FreeGC(display, textPtr->cursorOffGC);
    }
}

/*
 *--------------------------------------------------------------
 *
 * ComputeTextBbox --
 *
 *	This procedure is invoked to compute the bounding box of
 *	all the pixels that may be drawn as part of a text item.
 *	In addition, it recomputes all of the geometry information
 *	used to display a text item or check for mouse hits.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The fields x1, y1, x2, and y2 are updated in the header
 *	for itemPtr, and the linePtr structure is regenerated
 *	for itemPtr.
 *
 *--------------------------------------------------------------
 */

static void
ComputeTextBbox(canvas, textPtr)
    Tk_Canvas canvas;		/* Canvas that contains item. */
    TextItem *textPtr;		/* Item whose bbox is to be recomputed. */
{
    Tk_CanvasTextInfo *textInfoPtr;
    int leftX, topY, width, height, fudge;

    Tk_FreeTextLayout(textPtr->textLayout);
    textPtr->textLayout = Tk_ComputeTextLayout(textPtr->tkfont,
	    textPtr->text, textPtr->numChars, textPtr->width,
	    textPtr->justify, 0, &width, &height);

    /*
     * Use overall geometry information to compute the top-left corner
     * of the bounding box for the text item.
     */

    leftX = (int) (textPtr->x + 0.5);
    topY = (int) (textPtr->y + 0.5);
    switch (textPtr->anchor) {
	case TK_ANCHOR_NW:
	case TK_ANCHOR_N:
	case TK_ANCHOR_NE:
	    break;

	case TK_ANCHOR_W:
	case TK_ANCHOR_CENTER:
	case TK_ANCHOR_E:
	    topY -= height / 2;
	    break;

	case TK_ANCHOR_SW:
	case TK_ANCHOR_S:
	case TK_ANCHOR_SE:
	    topY -= height;
	    break;
    }
    switch (textPtr->anchor) {
	case TK_ANCHOR_NW:
	case TK_ANCHOR_W:
	case TK_ANCHOR_SW:
	    break;

	case TK_ANCHOR_N:
	case TK_ANCHOR_CENTER:
	case TK_ANCHOR_S:
	    leftX -= width / 2;
	    break;

	case TK_ANCHOR_NE:
	case TK_ANCHOR_E:
	case TK_ANCHOR_SE:
	    leftX -= width;
	    break;
    }

    textPtr->leftEdge  = leftX;
    textPtr->rightEdge = leftX + width;

    /*
     * Last of all, update the bounding box for the item.  The item's
     * bounding box includes the bounding box of all its lines, plus
     * an extra fudge factor for the cursor border (which could
     * potentially be quite large).
     */

    textInfoPtr = textPtr->textInfoPtr;
    fudge = (textInfoPtr->insertWidth + 1) / 2;
    if (textInfoPtr->selBorderWidth > fudge) {
	fudge = textInfoPtr->selBorderWidth;
    }
    textPtr->header.x1 = leftX - fudge;
    textPtr->header.y1 = topY;
    textPtr->header.x2 = leftX + width + fudge;
    textPtr->header.y2 = topY + height;
}

/*
 *--------------------------------------------------------------
 *
 * DisplayCanvText --
 *
 *	This procedure is invoked to draw a text item in a given
 *	drawable.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	ItemPtr is drawn in drawable using the transformation
 *	information in canvas.
 *
 *--------------------------------------------------------------
 */

static void
DisplayCanvText(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). */
{
    TextItem *textPtr;
    Tk_CanvasTextInfo *textInfoPtr;
    int selFirstChar, selLastChar;
    short drawableX, drawableY;

    textPtr = (TextItem *) itemPtr;
    textInfoPtr = textPtr->textInfoPtr;

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

    /*
     * If we're stippling, then modify the stipple offset in the GC.  Be
     * sure to reset the offset when done, since the GC is supposed to be
     * read-only.
     */

    if (textPtr->stipple != None) {
	Tk_CanvasSetStippleOrigin(canvas, textPtr->gc);
    }

    selFirstChar = -1;
    selLastChar = 0;		/* lint. */

    if (textInfoPtr->selItemPtr == itemPtr) {
	char *text;

	text = textPtr->text;
	selFirstChar = textInfoPtr->selectFirst;
	selLastChar = textInfoPtr->selectLast;
	if (selLastChar > textPtr->numChars) {
	    selLastChar = textPtr->numChars - 1;
	}
	if ((selFirstChar >= 0) && (selFirstChar <= selLastChar)) {
	    int xFirst, yFirst, hFirst;
	    int xLast, yLast;

	    /*
	     * Draw a special background under the selection.
	     */

	    Tk_CharBbox(textPtr->textLayout, selFirstChar, &xFirst, &yFirst,
		    NULL, &hFirst);
	    Tk_CharBbox(textPtr->textLayout, selLastChar, &xLast, &yLast,
		    NULL, NULL);

	    /*
	     * If the selection spans the end of this line, then display
	     * selection background all the way to the end of the line.
	     * However, for the last line we only want to display up to the
	     * last character, not the end of the line.
	     */

	    x = xFirst;
	    height = hFirst;
	    for (y = yFirst ; y <= yLast; y += height) {
		if (y == yLast) {
		    width = xLast - x;
		} else {	    
		    width = textPtr->rightEdge - textPtr->leftEdge - x;
		}
		Tk_CanvasDrawableCoords(canvas,
			(double) (textPtr->leftEdge + x
				- textInfoPtr->selBorderWidth),
			(double) (textPtr->header.y1 + y),
			&drawableX, &drawableY);
		Tk_Fill3DRectangle(Tk_CanvasTkwin(canvas), drawable,
			textInfoPtr->selBorder, drawableX, drawableY,
			width + 2 * textInfoPtr->selBorderWidth,
			height, textInfoPtr->selBorderWidth, TK_RELIEF_RAISED);
		x = 0;
	    }
	}
    }

    /*
     * If the insertion point should be displayed, then draw a special
     * background for the cursor before drawing the text.  Note:  if
     * we're the cursor item but the cursor is turned off, then redraw
     * background over the area of the cursor.  This guarantees that
     * the selection won't make the cursor invisible on mono displays,
     * where both are drawn in the same color.
     */

    if ((textInfoPtr->focusItemPtr == itemPtr) && (textInfoPtr->gotFocus)) {
	if (Tk_CharBbox(textPtr->textLayout, textPtr->insertPos,
		&x, &y, NULL, &height)) {
	    Tk_CanvasDrawableCoords(canvas,
		    (double) (textPtr->leftEdge + x
			    - (textInfoPtr->insertWidth / 2)),
		    (double) (textPtr->header.y1 + y),
		    &drawableX, &drawableY);
	    if (textInfoPtr->cursorOn) {
		Tk_Fill3DRectangle(Tk_CanvasTkwin(canvas), drawable,
			textInfoPtr->insertBorder,
			drawableX, drawableY,
			textInfoPtr->insertWidth, height,
			textInfoPtr->insertBorderWidth, TK_RELIEF_RAISED);
	    } else if (textPtr->cursorOffGC != None) {
		/*
		 * Redraw the background over the area of the cursor,
		 * even though the cursor is turned off.  This
		 * guarantees that the selection won't make the cursor
		 * invisible on mono displays, where both may be drawn
		 * in the same color.
		 */

		XFillRectangle(display, drawable, textPtr->cursorOffGC,
			drawableX, drawableY,
			(unsigned) textInfoPtr->insertWidth,
			(unsigned) height);
	    }
	}
    }


    /*
     * Display the text in two pieces: draw the entire text item, then
     * draw the selected text on top of it.  The selected text then
     * will only need to be drawn if it has different attributes (such
     * as foreground color) than regular text.
     */

    Tk_CanvasDrawableCoords(canvas, (double) textPtr->leftEdge,
	    (double) textPtr->header.y1, &drawableX, &drawableY);
    Tk_DrawTextLayout(display, drawable, textPtr->gc, textPtr->textLayout,
	    drawableX, drawableY, 0, -1);

    if ((selFirstChar >= 0) && (textPtr->selTextGC != textPtr->gc)) {
	Tk_DrawTextLayout(display, drawable, textPtr->selTextGC,
	    textPtr->textLayout, drawableX, drawableY, selFirstChar,
	    selLastChar + 1);
    }

    if (textPtr->stipple != None) {
	XSetTSOrigin(display, textPtr->gc, 0, 0);
    }
}

/*
 *--------------------------------------------------------------
 *
 * TextInsert --
 *
 *	Insert characters into a text item at a given position.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The text in the given item is modified.  The cursor and
 *	selection positions are also modified to reflect the
 *	insertion.
 *
 *--------------------------------------------------------------
 */

static void
TextInsert(canvas, itemPtr, index, string)
    Tk_Canvas canvas;		/* Canvas containing text item. */
    Tk_Item *itemPtr;		/* Text item to be modified. */
    int index;			/* Character index before which string is
				 * to be inserted. */
    char *string;		/* New characters to be inserted. */
{
    TextItem *textPtr = (TextItem *) itemPtr;
    int byteIndex, byteCount, charsAdded;
    char *new, *text;
    Tk_CanvasTextInfo *textInfoPtr = textPtr->textInfoPtr;

    text = textPtr->text;

    if (index < 0) {
	index = 0;
    }
    if (index > textPtr->numChars) {
	index = textPtr->numChars;
    }
    byteIndex = Tcl_UtfAtIndex(text, index) - text;
    byteCount = strlen(string);
    if (byteCount == 0) {
	return;
    }

    new = (char *) ckalloc((unsigned) textPtr->numBytes + byteCount + 1);
    memcpy(new, text, (size_t) byteIndex);
    strcpy(new + byteIndex, string);
    strcpy(new + byteIndex + byteCount, text + byteIndex);

    ckfree(text);
    textPtr->text = new;
    charsAdded = Tcl_NumUtfChars(string, byteCount);
    textPtr->numChars += charsAdded;
    textPtr->numBytes += byteCount;

    /*
     * Inserting characters invalidates indices such as those for the
     * selection and cursor.  Update the indices appropriately.
     */

    if (textInfoPtr->selItemPtr == itemPtr) {
	if (textInfoPtr->selectFirst >= index) {
	    textInfoPtr->selectFirst += charsAdded;
	}
	if (textInfoPtr->selectLast >= index) {
	    textInfoPtr->selectLast += charsAdded;
	}
	if ((textInfoPtr->anchorItemPtr == itemPtr)
		&& (textInfoPtr->selectAnchor >= index)) {
	    textInfoPtr->selectAnchor += charsAdded;
	}
    }
    if (textPtr->insertPos >= index) {
	textPtr->insertPos += charsAdded;
    }
    ComputeTextBbox(canvas, textPtr);
}

/*
 *--------------------------------------------------------------
 *
 * TextDeleteChars --
 *
 *	Delete one or more characters from a text item.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Characters between "first" and "last", inclusive, get
 *	deleted from itemPtr, and things like the selection
 *	position get updated.
 *
 *--------------------------------------------------------------
 */

static void
TextDeleteChars(canvas, itemPtr, first, last)
    Tk_Canvas canvas;		/* Canvas containing itemPtr. */
    Tk_Item *itemPtr;		/* Item in which to delete characters. */
    int first;			/* Character index of first character to
				 * delete. */
    int last;			/* Character index of last character to
				 * delete (inclusive). */
{
    TextItem *textPtr = (TextItem *) itemPtr;
    int byteIndex, byteCount, charsRemoved;
    char *new, *text;
    Tk_CanvasTextInfo *textInfoPtr = textPtr->textInfoPtr;

    text = textPtr->text;
    if (first < 0) {
	first = 0;
    }
    if (last >= textPtr->numChars) {
	last = textPtr->numChars - 1;
    }
    if (first > last) {
	return;
    }
    charsRemoved = last + 1 - first;

    byteIndex = Tcl_UtfAtIndex(text, first) - text;
    byteCount = Tcl_UtfAtIndex(text + byteIndex, charsRemoved)
	- (text + byteIndex);
    
    new = (char *) ckalloc((unsigned) (textPtr->numBytes + 1 - byteCount));
    memcpy(new, text, (size_t) byteIndex);
    strcpy(new + byteIndex, text + byteIndex + byteCount);

    ckfree(text);
    textPtr->text = new;
    textPtr->numChars -= charsRemoved;
    textPtr->numBytes -= byteCount;

    /*
     * Update indexes for the selection and cursor to reflect the
     * renumbering of the remaining characters.
     */

    if (textInfoPtr->selItemPtr == itemPtr) {
	if (textInfoPtr->selectFirst > first) {
	    textInfoPtr->selectFirst -= charsRemoved;
	    if (textInfoPtr->selectFirst < first) {
		textInfoPtr->selectFirst = first;
	    }
	}
	if (textInfoPtr->selectLast >= first) {
	    textInfoPtr->selectLast -= charsRemoved;
	    if (textInfoPtr->selectLast < first - 1) {
		textInfoPtr->selectLast = first - 1;
	    }
	}
	if (textInfoPtr->selectFirst > textInfoPtr->selectLast) {
	    textInfoPtr->selItemPtr = NULL;
	}
	if ((textInfoPtr->anchorItemPtr == itemPtr)
		&& (textInfoPtr->selectAnchor > first)) {
	    textInfoPtr->selectAnchor -= charsRemoved;
	    if (textInfoPtr->selectAnchor < first) {
		textInfoPtr->selectAnchor = first;
	    }
	}
    }
    if (textPtr->insertPos > first) {
	textPtr->insertPos -= charsRemoved;
	if (textPtr->insertPos < first) {
	    textPtr->insertPos = first;
	}
    }
    ComputeTextBbox(canvas, textPtr);
    return;
}

/*
 *--------------------------------------------------------------
 *
 * TextToPoint --
 *
 *	Computes the distance from a given point to a given
 *	text item, in canvas units.
 *
 * Results:
 *	The return value is 0 if the point whose x and y coordinates
 *	are pointPtr[0] and pointPtr[1] is inside the text item.  If
 *	the point isn't inside the text item then the return value
 *	is the distance from the point to the text item.
 *
 * Side effects:
 *	None.
 *
 *--------------------------------------------------------------
 */

static double
TextToPoint(canvas, itemPtr, pointPtr)
    Tk_Canvas canvas;		/* Canvas containing itemPtr. */
    Tk_Item *itemPtr;		/* Item to check against point. */
    double *pointPtr;		/* Pointer to x and y coordinates. */
{
    TextItem *textPtr;

    textPtr = (TextItem *) itemPtr;
    return (double) Tk_DistanceToTextLayout(textPtr->textLayout,
	    (int) pointPtr[0] - textPtr->leftEdge,
	    (int) pointPtr[1] - textPtr->header.y1);
}

/*
 *--------------------------------------------------------------
 *
 * TextToArea --
 *
 *	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.
 *
 *--------------------------------------------------------------
 */

static int
TextToArea(canvas, itemPtr, rectPtr)
    Tk_Canvas canvas;		/* Canvas containing itemPtr. */
    Tk_Item *itemPtr;		/* Item to check against rectangle. */
    double *rectPtr;		/* Pointer to array of four coordinates
				 * (x1, y1, x2, y2) describing rectangular
				 * area.  */
{
    TextItem *textPtr;

    textPtr = (TextItem *) itemPtr;
    return Tk_IntersectTextLayout(textPtr->textLayout,
	    (int) (rectPtr[0] + 0.5) - textPtr->leftEdge,
	    (int) (rectPtr[1] + 0.5) - textPtr->header.y1,
	    (int) (rectPtr[2] - rectPtr[0] + 0.5),
	    (int) (rectPtr[3] - rectPtr[1] + 0.5));
}

/*
 *--------------------------------------------------------------
 *
 * ScaleText --
 *
 *	This procedure is invoked to rescale a text item.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Scales the position of the text, but not the size
 *	of the font for the text.
 *
 *--------------------------------------------------------------
 */

	/* ARGSUSED */
static void
ScaleText(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 rect. */
    double scaleX;		/* Amount to scale in X direction. */
    double scaleY;		/* Amount to scale in Y direction. */
{
    TextItem *textPtr = (TextItem *) itemPtr;

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

static void
TranslateText(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. */
{
    TextItem *textPtr = (TextItem *) itemPtr;

    textPtr->x += deltaX;
    textPtr->y += deltaY;
    ComputeTextBbox(canvas, textPtr);
}

/*
 *--------------------------------------------------------------
 *
 * GetTextIndex --
 *
 *	Parse an index into a text item and return either its value
 *	or an error.
 *
 * Results:
 *	A standard Tcl result.  If all went well, then *indexPtr is
 *	filled in with the index (into itemPtr) corresponding to
 *	string.  Otherwise an error message is left in
 *	the interp's result.
 *
 * Side effects:
 *	None.
 *
 *--------------------------------------------------------------
 */

static int
GetTextIndex(interp, canvas, itemPtr, string, indexPtr)
    Tcl_Interp *interp;		/* Used for error reporting. */
    Tk_Canvas canvas;		/* Canvas containing item. */
    Tk_Item *itemPtr;		/* Item for which the index is being
				 * specified. */
    char *string;		/* Specification of a particular character
				 * in itemPtr's text. */
    int *indexPtr;		/* Where to store converted character
				 * index. */
{
    TextItem *textPtr = (TextItem *) itemPtr;
    size_t length;
    int c;
    TkCanvas *canvasPtr = (TkCanvas *) canvas;
    Tk_CanvasTextInfo *textInfoPtr = textPtr->textInfoPtr;

    c = string[0];
    length = strlen(string);

    if ((c == 'e') && (strncmp(string, "end", length) == 0)) {
	*indexPtr = textPtr->numChars;
    } else if ((c == 'i') && (strncmp(string, "insert", length) == 0)) {
	*indexPtr = textPtr->insertPos;
    } else if ((c == 's') && (strncmp(string, "sel.first", length) == 0)
	    && (length >= 5)) {
	if (textInfoPtr->selItemPtr != itemPtr) {
	    Tcl_SetResult(interp, "selection isn't in item", TCL_STATIC);
	    return TCL_ERROR;
	}
	*indexPtr = textInfoPtr->selectFirst;
    } else if ((c == 's') && (strncmp(string, "sel.last", length) == 0)
	    && (length >= 5)) {
	if (textInfoPtr->selItemPtr != itemPtr) {
	    Tcl_SetResult(interp, "selection isn't in item", TCL_STATIC);
	    return TCL_ERROR;
	}
	*indexPtr = textInfoPtr->selectLast;
    } else if (c == '@') {
	int x, y;
	double tmp;
	char *end, *p;

	p = string+1;
	tmp = strtod(p, &end);
	if ((end == p) || (*end != ',')) {
	    goto badIndex;
	}
	x = (int) ((tmp < 0) ? tmp - 0.5 : tmp + 0.5);
	p = end+1;
	tmp = strtod(p, &end);
	if ((end == p) || (*end != 0)) {
	    goto badIndex;
	}
	y = (int) ((tmp < 0) ? tmp - 0.5 : tmp + 0.5);
	*indexPtr = Tk_PointToChar(textPtr->textLayout,
		x + canvasPtr->scrollX1 - textPtr->leftEdge,
		y + canvasPtr->scrollY1 - textPtr->header.y1);
    } else if (Tcl_GetInt(interp, string, indexPtr) == TCL_OK) {
	if (*indexPtr < 0){
	    *indexPtr = 0;
	} else if (*indexPtr > textPtr->numChars) {
	    *indexPtr = textPtr->numChars;
	}
    } else {
	/*
	 * Some of the paths here leave messages in the interp's result,
	 * so we have to clear it out before storing our own message.
	 */

	badIndex:
	Tcl_SetResult(interp, (char *) NULL, TCL_STATIC);
	Tcl_AppendResult(interp, "bad index \"", string, "\"",
		(char *) NULL);
	return TCL_ERROR;
    }
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * SetTextCursor --
 *
 *	Set the position of the insertion cursor in this item.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The cursor position will change.
 *
 *--------------------------------------------------------------
 */

	/* ARGSUSED */
static void
SetTextCursor(canvas, itemPtr, index)
    Tk_Canvas canvas;		/* Record describing canvas widget. */
    Tk_Item *itemPtr;		/* Text item in which cursor position is to
				 * be set. */
    int index;			/* Character index of character just before
				 * which cursor is to be positioned. */
{
    TextItem *textPtr = (TextItem *) itemPtr;

    if (index < 0) {
	textPtr->insertPos = 0;
    } else  if (index > textPtr->numChars) {
	textPtr->insertPos = textPtr->numChars;
    } else {
	textPtr->insertPos = index;
    }
}

/*
 *--------------------------------------------------------------
 *
 * GetSelText --
 *
 *	This procedure is invoked to return the selected portion
 *	of a text item.  It is only called when this item has
 *	the selection.
 *
 * Results:
 *	The return value is the number of non-NULL bytes stored
 *	at buffer.  Buffer is filled (or partially filled) with a
 *	NULL-terminated string containing part or all of the selection,
 *	as given by offset and maxBytes.
 *
 * Side effects:
 *	None.
 *
 *--------------------------------------------------------------
 */

static int
GetSelText(canvas, itemPtr, offset, buffer, maxBytes)
    Tk_Canvas canvas;		/* Canvas containing selection. */
    Tk_Item *itemPtr;		/* Text item containing selection. */
    int offset;			/* Byte offset within selection of first
				 * character to be returned. */
    char *buffer;		/* Location in which to place selection. */
    int maxBytes;		/* Maximum number of bytes to place at
				 * buffer, not including terminating NULL
				 * character. */
{
    TextItem *textPtr = (TextItem *) itemPtr;
    int byteCount; 
    char *text, *selStart, *selEnd;
    Tk_CanvasTextInfo *textInfoPtr = textPtr->textInfoPtr;

    if ((textInfoPtr->selectFirst < 0) ||
	    (textInfoPtr->selectFirst > textInfoPtr->selectLast)) {
	return 0;
    }
    text = textPtr->text;
    selStart = Tcl_UtfAtIndex(text, textInfoPtr->selectFirst);
    selEnd = Tcl_UtfAtIndex(selStart,
	    textInfoPtr->selectLast + 1 - textInfoPtr->selectFirst);
    byteCount = selEnd - selStart - offset;
    if (byteCount > maxBytes) {
	byteCount = maxBytes;
    }
    if (byteCount <= 0) {
	return 0;
    }
    memcpy(buffer, selStart + offset, (size_t) byteCount);
    buffer[byteCount] = '\0';
    return byteCount;
}

/*
 *--------------------------------------------------------------
 *
 * TextToPostscript --
 *
 *	This procedure is called to generate Postscript for
 *	text 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
TextToPostscript(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. */
{
    TextItem *textPtr = (TextItem *) itemPtr;
    int x, y;
    Tk_FontMetrics fm;
    char *justify;
    char buffer[500];

    if (textPtr->color == NULL) {
	return TCL_OK;
    }

    if (Tk_CanvasPsFont(interp, canvas, textPtr->tkfont) != TCL_OK) {
	return TCL_ERROR;
    }
    if (prepass != 0) {
	return TCL_OK;
    }
    if (Tk_CanvasPsColor(interp, canvas, textPtr->color) != TCL_OK) {
	return TCL_ERROR;
    }
    if (textPtr->stipple != None) {
	Tcl_AppendResult(interp, "/StippleText {\n    ",
		(char *) NULL);
	Tk_CanvasPsStipple(interp, canvas, textPtr->stipple);
	Tcl_AppendResult(interp, "} bind def\n", (char *) NULL);
    }

    sprintf(buffer, "%.15g %.15g [\n", textPtr->x,
	    Tk_CanvasPsY(canvas, textPtr->y));
    Tcl_AppendResult(interp, buffer, (char *) NULL);

    Tk_TextLayoutToPostscript(interp, textPtr->textLayout);

    x = 0;  y = 0;  justify = NULL;	/* lint. */
    switch (textPtr->anchor) {
	case TK_ANCHOR_NW:	x = 0; y = 0;	break;
	case TK_ANCHOR_N:	x = 1; y = 0;	break;
	case TK_ANCHOR_NE:	x = 2; y = 0;	break;
	case TK_ANCHOR_E:	x = 2; y = 1;	break;
	case TK_ANCHOR_SE:	x = 2; y = 2;	break;
	case TK_ANCHOR_S:	x = 1; y = 2;	break;
	case TK_ANCHOR_SW:	x = 0; y = 2;	break;
	case TK_ANCHOR_W:	x = 0; y = 1;	break;
	case TK_ANCHOR_CENTER:	x = 1; y = 1;	break;
    }
    switch (textPtr->justify) {
        case TK_JUSTIFY_LEFT:	justify = "0";	break;
	case TK_JUSTIFY_CENTER: justify = "0.5";break;
	case TK_JUSTIFY_RIGHT:  justify = "1";	break;
    }

    Tk_GetFontMetrics(textPtr->tkfont, &fm);
    sprintf(buffer, "] %d %g %g %s %s DrawText\n",
	    fm.linespace, x / -2.0, y / 2.0, justify,
	    ((textPtr->stipple == None) ? "false" : "true"));
    Tcl_AppendResult(interp, buffer, (char *) NULL);

    return TCL_OK;
}