Import Micropolis from http://www.donhopkins.com/home/micropolis/

[micropolis] / src / tk / tktext.c

/* 
 * tkText.c --
 *
 *      This module provides a big chunk of the implementation of
 *      multi-line editable text widgets for Tk.  Among other things,
 *      it provides the Tcl command interfaces to text widgets and
 *      the display code.  The B-tree representation of text is
 *      implemented elsewhere.
 *
 * Copyright 1992 Regents of the University of California.
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies.  The University of California
 * makes no representations about the suitability of this
 * software for any purpose.  It is provided "as is" without
 * express or implied warranty.
 */

#ifndef lint
static char rcsid[] = "$Header: /user6/ouster/wish/RCS/tkText.c,v 1.23 92/08/14 14:45:44 ouster Exp $ SPRITE (Berkeley)";
#endif

#include "default.h"
#include "tkconfig.h"
#include "tk.h"
#include "tktext.h"

/*
 * Information used to parse text configuration options:
 */

static Tk_ConfigSpec configSpecs[] = {
    {TK_CONFIG_BORDER, "-background", "background", "Background",
        DEF_TEXT_BG_COLOR, Tk_Offset(TkText, border), TK_CONFIG_COLOR_ONLY},
    {TK_CONFIG_BORDER, "-background", "background", "Background",
        DEF_TEXT_BG_MONO, Tk_Offset(TkText, border), TK_CONFIG_MONO_ONLY},
    {TK_CONFIG_SYNONYM, "-bd", "borderWidth", (char *) NULL,
        (char *) NULL, 0, 0},
    {TK_CONFIG_SYNONYM, "-bg", "background", (char *) NULL,
        (char *) NULL, 0, 0},
    {TK_CONFIG_PIXELS, "-borderwidth", "borderWidth", "BorderWidth",
        DEF_TEXT_BORDER_WIDTH, Tk_Offset(TkText, borderWidth), 0},
    {TK_CONFIG_ACTIVE_CURSOR, "-cursor", "cursor", "Cursor",
        DEF_TEXT_CURSOR, Tk_Offset(TkText, cursor), TK_CONFIG_NULL_OK},
    {TK_CONFIG_BOOLEAN, "-exportselection", "exportSelection",
        "ExportSelection", DEF_TEXT_EXPORT_SELECTION,
        Tk_Offset(TkText, exportSelection), 0},
    {TK_CONFIG_SYNONYM, "-fg", "foreground", (char *) NULL,
        (char *) NULL, 0, 0},
    {TK_CONFIG_FONT, "-font", "font", "Font",
        DEF_TEXT_FONT, Tk_Offset(TkText, fontPtr), 0},
    {TK_CONFIG_COLOR, "-foreground", "foreground", "Foreground",
        DEF_TEXT_FG, Tk_Offset(TkText, fgColor), 0},
    {TK_CONFIG_INT, "-height", "height", "Height",
        DEF_TEXT_HEIGHT, Tk_Offset(TkText, height), 0},
    {TK_CONFIG_BORDER, "-insertbackground", "insertBackground", "Foreground",
        DEF_TEXT_INSERT_BG, Tk_Offset(TkText, insertBorder), 0},
    {TK_CONFIG_PIXELS, "-insertborderwidth", "insertBorderWidth", "BorderWidth",
        DEF_TEXT_INSERT_BD_COLOR, Tk_Offset(TkText, insertBorderWidth),
        TK_CONFIG_COLOR_ONLY},
    {TK_CONFIG_PIXELS, "-insertborderwidth", "insertBorderWidth", "BorderWidth",
        DEF_TEXT_INSERT_BD_MONO, Tk_Offset(TkText, insertBorderWidth),
        TK_CONFIG_MONO_ONLY},
    {TK_CONFIG_INT, "-insertofftime", "insertOffTime", "OffTime",
        DEF_TEXT_INSERT_OFF_TIME, Tk_Offset(TkText, insertOffTime), 0},
    {TK_CONFIG_INT, "-insertontime", "insertOnTime", "OnTime",
        DEF_TEXT_INSERT_ON_TIME, Tk_Offset(TkText, insertOnTime), 0},
    {TK_CONFIG_PIXELS, "-insertwidth", "insertWidth", "InsertWidth",
        DEF_TEXT_INSERT_WIDTH, Tk_Offset(TkText, insertWidth), 0},
    {TK_CONFIG_PIXELS, "-padx", "padX", "Pad",
        DEF_TEXT_PADX, Tk_Offset(TkText, padX), 0},
    {TK_CONFIG_PIXELS, "-pady", "padY", "Pad",
        DEF_TEXT_PADY, Tk_Offset(TkText, padY), 0},
    {TK_CONFIG_RELIEF, "-relief", "relief", "Relief",
        DEF_TEXT_RELIEF, Tk_Offset(TkText, relief), 0},
    {TK_CONFIG_BORDER, "-selectbackground", "selectBackground", "Foreground",
        DEF_ENTRY_SELECT_COLOR, Tk_Offset(TkText, selBorder),
        TK_CONFIG_COLOR_ONLY},
    {TK_CONFIG_BORDER, "-selectbackground", "selectBackground", "Foreground",
        DEF_TEXT_SELECT_MONO, Tk_Offset(TkText, selBorder),
        TK_CONFIG_MONO_ONLY},
    {TK_CONFIG_PIXELS, "-selectborderwidth", "selectBorderWidth", "BorderWidth",
        DEF_TEXT_SELECT_BD_COLOR, Tk_Offset(TkText, selBorderWidth),
        TK_CONFIG_COLOR_ONLY},
    {TK_CONFIG_PIXELS, "-selectborderwidth", "selectBorderWidth", "BorderWidth",
        DEF_TEXT_SELECT_BD_MONO, Tk_Offset(TkText, selBorderWidth),
        TK_CONFIG_MONO_ONLY},
    {TK_CONFIG_COLOR, "-selectforeground", "selectForeground", "Background",
        DEF_TEXT_SELECT_FG_COLOR, Tk_Offset(TkText, selFgColorPtr),
        TK_CONFIG_COLOR_ONLY},
    {TK_CONFIG_COLOR, "-selectforeground", "selectForeground", "Background",
        DEF_TEXT_SELECT_FG_MONO, Tk_Offset(TkText, selFgColorPtr),
        TK_CONFIG_MONO_ONLY},
    {TK_CONFIG_BOOLEAN, "-setgrid", "setGrid", "SetGrid",
        DEF_TEXT_SET_GRID, Tk_Offset(TkText, setGrid), 0},
    {TK_CONFIG_UID, "-state", "state", "State",
        DEF_TEXT_STATE, Tk_Offset(TkText, state), 0},
    {TK_CONFIG_INT, "-width", "width", "Width",
        DEF_TEXT_WIDTH, Tk_Offset(TkText, width), 0},
    {TK_CONFIG_UID, "-wrap", "wrap", "Wrap",
        DEF_TEXT_WRAP, Tk_Offset(TkText, wrapMode), 0},
    {TK_CONFIG_STRING, "-yscrollcommand", "yScrollCommand", "ScrollCommand",
        DEF_TEXT_YSCROLL_COMMAND, Tk_Offset(TkText, yScrollCmd),
        TK_CONFIG_NULL_OK},
    {TK_CONFIG_END, (char *) NULL, (char *) NULL, (char *) NULL,
        (char *) NULL, 0, 0}
};

/*
 * The following definition specifies the maximum number of characters
 * needed in a string to hold a position specifier.
 */

#define POS_CHARS 30

/*
 * Tk_Uid's used to represent text states:
 */

Tk_Uid tkTextCharUid = NULL;
Tk_Uid tkTextDisabledUid = NULL;
Tk_Uid tkTextNoneUid = NULL;
Tk_Uid tkTextNormalUid = NULL;
Tk_Uid tkTextWordUid = NULL;

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

static int              ConfigureText _ANSI_ARGS_((Tcl_Interp *interp,
                            TkText *textPtr, int argc, char **argv, int flags));
static void             DeleteChars _ANSI_ARGS_((TkText *textPtr, int line1,
                            int ch1, int line2, int ch2));
static void             DestroyText _ANSI_ARGS_((ClientData clientData));
static void             InsertChars _ANSI_ARGS_((TkText *textPtr, int line,
                            int ch, char *string));
static void             TextBlinkProc _ANSI_ARGS_((ClientData clientData));
static void             TextEventProc _ANSI_ARGS_((ClientData clientData,
                            XEvent *eventPtr));
static int              TextFetchSelection _ANSI_ARGS_((ClientData clientData,
                            int offset, char *buffer, int maxBytes));
static void             TextFocusProc _ANSI_ARGS_((ClientData clientData,
                            int gotFocus));
static int              TextMarkCmd _ANSI_ARGS_((TkText *textPtr,
                            Tcl_Interp *interp, int argc, char **argv));
static int              TextScanCmd _ANSI_ARGS_((TkText *textPtr,
                            Tcl_Interp *interp, int argc, char **argv));
static int              TextWidgetCmd _ANSI_ARGS_((ClientData clientData,
                            Tcl_Interp *interp, int argc, char **argv));
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_TextCmd --
 *
 *      This procedure is invoked to process the "text" Tcl command.
 *      See the user documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *--------------------------------------------------------------
 */

int
Tk_TextCmd(clientData, interp, argc, argv)
    ClientData clientData;      /* Main window associated with
                                 * interpreter. */
    Tcl_Interp *interp;         /* Current interpreter. */
    int argc;                   /* Number of arguments. */
    char **argv;                /* Argument strings. */
{
    Tk_Window tkwin = (Tk_Window) clientData;
    Tk_Window new;
    register TkText *textPtr;

    if (argc < 2) {
        Tcl_AppendResult(interp, "wrong # args: should be \"",
                argv[0], " pathName ?options?\"", (char *) NULL);
        return TCL_ERROR;
    }

    /*
     * Perform once-only initialization:
     */

    if (tkTextNormalUid == NULL) {
        tkTextCharUid = Tk_GetUid("char");
        tkTextDisabledUid = Tk_GetUid("disabled");
        tkTextNoneUid = Tk_GetUid("none");
        tkTextNormalUid = Tk_GetUid("normal");
        tkTextWordUid = Tk_GetUid("word");
    }

    /*
     * Create the window.
     */

    new = Tk_CreateWindowFromPath(interp, tkwin, argv[1], (char *) NULL);
    if (new == NULL) {
        return TCL_ERROR;
    }

    textPtr = (TkText *) ckalloc(sizeof(TkText));
    textPtr->tkwin = new;
    textPtr->interp = interp;
    textPtr->tree = TkBTreeCreate();
    Tcl_InitHashTable(&textPtr->tagTable, TCL_STRING_KEYS);
    textPtr->numTags = 0;
    Tcl_InitHashTable(&textPtr->markTable, TCL_STRING_KEYS);
    textPtr->state = tkTextNormalUid;
    textPtr->border = NULL;
    textPtr->cursor = None;
    textPtr->fgColor = NULL;
    textPtr->fontPtr = NULL;
    textPtr->prevWidth = Tk_Width(new);
    textPtr->prevHeight = Tk_Height(new);
    textPtr->topLinePtr = NULL;
// Moved down so flags were set right.
//    TkTextCreateDInfo(textPtr);
//    TkTextSetView(textPtr, 0, 0);
    textPtr->selBorder = NULL;
    textPtr->selFgColorPtr = NULL;
    textPtr->exportSelection = 1;
    textPtr->selOffset = -1;
    textPtr->insertAnnotPtr = NULL;
    textPtr->insertBorder = NULL;
    textPtr->insertBlinkHandler = (Tk_TimerToken) NULL;
    textPtr->bindingTable = NULL;
    textPtr->pickEvent.type = LeaveNotify;
    textPtr->yScrollCmd = NULL;
    textPtr->scanMarkLine = 0;
    textPtr->scanMarkY = 0;
    textPtr->flags = 0;
    textPtr->updateTimerToken = 0; // Added by Don to optimize rapid updates.
    TkTextCreateDInfo(textPtr);
    TkTextSetView(textPtr, 0, 0);

    /*
     * Create the "sel" tag and the "current" and "insert" marks.
     */

    textPtr->selTagPtr = TkTextCreateTag(textPtr, "sel");
    textPtr->selTagPtr->relief = TK_RELIEF_RAISED;
    textPtr->currentAnnotPtr = TkTextSetMark(textPtr, "current", 0, 0);
    textPtr->insertAnnotPtr = TkTextSetMark(textPtr, "insert", 0, 0);

    Tk_SetClass(new, "Text");
    Tk_CreateEventHandler(textPtr->tkwin, ExposureMask|StructureNotifyMask,
            TextEventProc, (ClientData) textPtr);
    Tk_CreateEventHandler(textPtr->tkwin, KeyPressMask|KeyReleaseMask
            |ButtonPressMask|ButtonReleaseMask|EnterWindowMask
            |LeaveWindowMask|PointerMotionMask, TkTextBindProc,
            (ClientData) textPtr);
    Tk_CreateSelHandler(textPtr->tkwin, XA_STRING, TextFetchSelection,
            (ClientData) textPtr, XA_STRING);
    Tcl_CreateCommand(interp, Tk_PathName(textPtr->tkwin),
            TextWidgetCmd, (ClientData) textPtr, (void (*)()) NULL);
    if (ConfigureText(interp, textPtr, argc-2, argv+2, 0) != TCL_OK) {
        Tk_DestroyWindow(textPtr->tkwin);
        return TCL_ERROR;
    }
    Tk_CreateFocusHandler(textPtr->tkwin, TextFocusProc, (ClientData) textPtr);
    interp->result = Tk_PathName(textPtr->tkwin);

    return TCL_OK;
}
\f
/*
 *--------------------------------------------------------------
 *
 * TextWidgetCmd --
 *
 *      This procedure is invoked to process the Tcl command
 *      that corresponds to a text widget.  See the user
 *      documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *--------------------------------------------------------------
 */

static int
TextWidgetCmd(clientData, interp, argc, argv)
    ClientData clientData;      /* Information about text widget. */
    Tcl_Interp *interp;         /* Current interpreter. */
    int argc;                   /* Number of arguments. */
    char **argv;                /* Argument strings. */
{
    register TkText *textPtr = (TkText *) clientData;
    int result = TCL_OK;
    int length;
    char c;
    int line1, line2, ch1, ch2;

    if (argc < 2) {
        Tcl_AppendResult(interp, "wrong # args: should be \"",
                argv[0], " option ?arg arg ...?\"", (char *) NULL);
        return TCL_ERROR;
    }
    Tk_Preserve((ClientData) textPtr);
    c = argv[1][0];
    length = strlen(argv[1]);
    if ((c == 'c') && (strncmp(argv[1], "compare", length) == 0)
            && (length >= 3)) {
        int less, equal, greater, value;
        char *p;

        if (argc != 5) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " compare index1 op index2\"", (char *) NULL);
            result = TCL_ERROR;
            goto done;
        }
        if ((TkTextGetIndex(interp, textPtr, argv[2], &line1, &ch1) != TCL_OK)
                || (TkTextGetIndex(interp, textPtr, argv[4], &line2, &ch2)
                != TCL_OK)) {
            result = TCL_ERROR;
            goto done;
        }
        less = equal = greater = 0;
        if (line1 < line2) {
            less = 1;
        } else if (line1 > line2) {
            greater = 1;
        } else {
            if (ch1 < ch2) {
                less = 1;
            } else if (ch1 > ch2) {
                greater = 1;
            } else {
                equal = 1;
            }
        }
        p = argv[3];
        if (p[0] == '<') {
                value = less;
            if ((p[1] == '=') && (p[2] == 0)) {
                value = less || equal;
            } else if (p[1] != 0) {
                compareError:
                Tcl_AppendResult(interp, "bad comparison operator \"",
                        argv[3], "\": must be <, <=, ==, >=, >, or !=",
                        (char *) NULL);
                result = TCL_ERROR;
                goto done;
            }
        } else if (p[0] == '>') {
                value = greater;
            if ((p[1] == '=') && (p[2] == 0)) {
                value = greater || equal;
            } else if (p[1] != 0) {
                goto compareError;
            }
        } else if ((p[0] == '=') && (p[1] == '=') && (p[2] == 0)) {
            value = equal;
        } else if ((p[0] == '!') && (p[1] == '=') && (p[2] == 0)) {
            value = !equal;
        } else {
            goto compareError;
        }
        interp->result = (value) ? "1" : "0";
    } else if ((c == 'c') && (strncmp(argv[1], "configure", length) == 0)
            && (length >= 3)) {
        if (argc == 2) {
            result = Tk_ConfigureInfo(interp, textPtr->tkwin, configSpecs,
                    (char *) textPtr, (char *) NULL, 0);
        } else if (argc == 3) {
            result = Tk_ConfigureInfo(interp, textPtr->tkwin, configSpecs,
                    (char *) textPtr, argv[2], 0);
        } else {
            result = ConfigureText(interp, textPtr, argc-2, argv+2,
                    TK_CONFIG_ARGV_ONLY);
        }
    } else if ((c == 'd') && (strncmp(argv[1], "debug", length) == 0)
            && (length >= 3)) {
        if (argc > 3) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " debug ?on|off?\"", (char *) NULL);
            result = TCL_ERROR;
            goto done;
        }
        if (argc == 2) {
            interp->result = (tkBTreeDebug) ? "on" : "off";
        } else {
            if (Tcl_GetBoolean(interp, argv[2], &tkBTreeDebug) != TCL_OK) {
                result = TCL_ERROR;
                goto done;
            }
        }
    } else if ((c == 'd') && (strncmp(argv[1], "delete", length) == 0)
            && (length >= 3)) {
        if ((argc != 3) && (argc != 4)) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " delete index1 ?index2?\"", (char *) NULL);
            result = TCL_ERROR;
            goto done;
        }
        if (TkTextGetIndex(interp, textPtr, argv[2], &line1, &ch1) != TCL_OK) {
            result = TCL_ERROR;
            goto done;
        }
        if (argc == 3) {
            line2 = line1;
            ch2 = ch1+1;
        } else if (TkTextGetIndex(interp, textPtr, argv[3], &line2, &ch2)
                != TCL_OK) {
            result = TCL_ERROR;
            goto done;
        }
        if (textPtr->state == tkTextNormalUid) {
            DeleteChars(textPtr, line1, ch1, line2, ch2);
        }
    } else if ((c == 'g') && (strncmp(argv[1], "get", length) == 0)) {
        register TkTextLine *linePtr;

        if ((argc != 3) && (argc != 4)) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " get index1 ?index2?\"", (char *) NULL);
            result = TCL_ERROR;
            goto done;
        }
        if (TkTextGetIndex(interp, textPtr, argv[2], &line1, &ch1) != TCL_OK) {
            result = TCL_ERROR;
            goto done;
        }
        if (argc == 3) {
            line2 = line1;
            ch2 = ch1+1;
        } else if (TkTextGetIndex(interp, textPtr, argv[3], &line2, &ch2)
                != TCL_OK) {
            result = TCL_ERROR;
            goto done;
        }
        if (line1 < 0) {
            line1 = 0;
            ch1 = 0;
        }
        for (linePtr = TkBTreeFindLine(textPtr->tree, line1);
                (linePtr != NULL) && (line1 <= line2);
                linePtr = TkBTreeNextLine(linePtr), line1++, ch1 = 0) {
            int savedChar, last;

            if (line1 == line2) {
                last = ch2;
                if (last > linePtr->numBytes) {
                    last = linePtr->numBytes;
                }
            } else {
                last = linePtr->numBytes;
            }
            if (ch1 >= last) {
                continue;
            }
            savedChar = linePtr->bytes[last];
            linePtr->bytes[last] = 0;
            Tcl_AppendResult(interp, linePtr->bytes+ch1, (char *) NULL);
            linePtr->bytes[last] = savedChar;
        }
    } else if ((c == 'i') && (strncmp(argv[1], "index", length) == 0)
            && (length >= 3)) {
        if (argc != 3) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " index index\"",
                    (char *) NULL);
            result = TCL_ERROR;
            goto done;
        }
        if (TkTextGetIndex(interp, textPtr, argv[2], &line1, &ch1) != TCL_OK) {
            result = TCL_ERROR;
            goto done;
        }
        TkTextPrintIndex(line1, ch1, interp->result);
    } else if ((c == 'i') && (strncmp(argv[1], "insert", length) == 0)
            && (length >= 3)) {
        if (argc != 4) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " insert index chars ?chars ...?\"",
                    (char *) NULL);
            result = TCL_ERROR;
            goto done;
        }
        if (TkTextGetIndex(interp, textPtr, argv[2], &line1, &ch1) != TCL_OK) {
            result = TCL_ERROR;
            goto done;
        }
        if (textPtr->state == tkTextNormalUid) {
            InsertChars(textPtr, line1, ch1, argv[3]);
        }
    } else if ((c == 'm') && (strncmp(argv[1], "mark", length) == 0)) {
        result = TextMarkCmd(textPtr, interp, argc, argv);
    } else if ((c == 's') && (strcmp(argv[1], "scan") == 0)) {
        result = TextScanCmd(textPtr, interp, argc, argv);
    } else if ((c == 't') && (strcmp(argv[1], "tag") == 0)) {
        result = TkTextTagCmd(textPtr, interp, argc, argv);
    } else if ((c == 'y') && (strncmp(argv[1], "yview", length) == 0)) {
        int numLines, pickPlace;

        if (argc < 3) {
            yviewSyntax:
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " yview ?-pickplace? lineNum|index\"",
                    (char *) NULL);
            result = TCL_ERROR;
            goto done;
        }
        pickPlace = 0;
        if (argv[2][0] == '-') {
            int switchLength;

            switchLength = strlen(argv[2]);
            if ((switchLength >= 2)
                    && (strncmp(argv[2], "-pickplace", switchLength) == 0)) {
                pickPlace = 1;
            }
        }
        if ((pickPlace+3) != argc) {
            goto yviewSyntax;
        }
        if (Tcl_GetInt(interp, argv[2+pickPlace], &line1) != TCL_OK) {
            Tcl_ResetResult(interp);
            if (TkTextGetIndex(interp, textPtr, argv[2+pickPlace],
                    &line1, &ch1) != TCL_OK) {
                result = TCL_ERROR;
                goto done;
            }
        }
        numLines = TkBTreeNumLines(textPtr->tree);
        if (line1 >= numLines) {
            line1 = numLines-1;
        }
        if (line1 < 0) {
            line1 = 0;
        }
        TkTextSetView(textPtr, line1, pickPlace);
    } else {
        Tcl_AppendResult(interp, "bad option \"", argv[1],
                "\":  must be compare, configure, debug, delete, get, ",
                "index, insert, mark, scan, tag, or yview",
                (char *) NULL);
        result = TCL_ERROR;
    }

    done:
    Tk_Release((ClientData) textPtr);
    return result;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * DestroyText --
 *
 *      This procedure is invoked by Tk_EventuallyFree or Tk_Release
 *      to clean up the internal structure of a text at a safe time
 *      (when no-one is using it anymore).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Everything associated with the text is freed up.
 *
 *----------------------------------------------------------------------
 */

static void
DestroyText(clientData)
    ClientData clientData;      /* Info about text widget. */
{
    register TkText *textPtr = (TkText *) clientData;
    Tcl_HashSearch search;
    Tcl_HashEntry *hPtr;
    TkTextTag *tagPtr;

    TkBTreeDestroy(textPtr->tree);
    for (hPtr = Tcl_FirstHashEntry(&textPtr->tagTable, &search);
            hPtr != NULL; hPtr = Tcl_NextHashEntry(&search)) {
        tagPtr = (TkTextTag *) Tcl_GetHashValue(hPtr);
        TkTextFreeTag(tagPtr);
    }
    Tcl_DeleteHashTable(&textPtr->tagTable);
    for (hPtr = Tcl_FirstHashEntry(&textPtr->markTable, &search);
            hPtr != NULL; hPtr = Tcl_NextHashEntry(&search)) {
        ckfree((char *) Tcl_GetHashValue(hPtr));
    }
    Tcl_DeleteHashTable(&textPtr->markTable);
    if (textPtr->border != NULL) {
        Tk_Free3DBorder(textPtr->border);
    }
    if (textPtr->cursor != None) {
        Tk_FreeCursor(textPtr->cursor);
    }
    if (textPtr->fgColor != NULL) {
        Tk_FreeColor(textPtr->fgColor);
    }
    if (textPtr->fontPtr != NULL) {
        Tk_FreeFontStruct(textPtr->fontPtr);
    }
    TkTextFreeDInfo(textPtr);

    /*
     * NOTE: do NOT free up selBorder or selFgColorPtr:  they are
     * duplicates of information in the "sel" tag, which was freed
     * up as part of deleting the tags above.
     */

    if (textPtr->insertBorder != NULL) {
        Tk_Free3DBorder(textPtr->insertBorder);
    }
    if (textPtr->insertBlinkHandler != NULL) {
        Tk_DeleteTimerHandler(textPtr->insertBlinkHandler);
    }
    if (textPtr->updateTimerToken != NULL) {
        Tk_DeleteTimerHandler(textPtr->updateTimerToken);
        textPtr->updateTimerToken = 0;
    }
    if (textPtr->bindingTable != NULL) {
        Tk_DeleteBindingTable(textPtr->bindingTable);
    }
    if (textPtr->yScrollCmd != NULL) {
        ckfree(textPtr->yScrollCmd);
    }
    ckfree((char *) textPtr);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * ConfigureText --
 *
 *      This procedure is called to process an argv/argc list, plus
 *      the Tk option database, in order to configure (or
 *      reconfigure) a text widget.
 *
 * Results:
 *      The return value is a standard Tcl result.  If TCL_ERROR is
 *      returned, then interp->result contains an error message.
 *
 * Side effects:
 *      Configuration information, such as text string, colors, font,
 *      etc. get set for textPtr;  old resources get freed, if there
 *      were any.
 *
 *----------------------------------------------------------------------
 */

static int
ConfigureText(interp, textPtr, argc, argv, flags)
    Tcl_Interp *interp;         /* Used for error reporting. */
    register TkText *textPtr;   /* Information about widget;  may or may
                                 * not already have values for some fields. */
    int argc;                   /* Number of valid entries in argv. */
    char **argv;                /* Arguments. */
    int flags;                  /* Flags to pass to Tk_ConfigureWidget. */
{
    int oldExport = textPtr->exportSelection;
    int charWidth, charHeight;

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

    /*
     * A few other options also need special processing, such as parsing
     * the geometry and setting the background from a 3-D border.
     */

    if ((textPtr->state != tkTextNormalUid)
            && (textPtr->state != tkTextDisabledUid)) {
        Tcl_AppendResult(interp, "bad state value \"", textPtr->state,
                "\":  must be normal or disabled", (char *) NULL);
        textPtr->state = tkTextNormalUid;
        return TCL_ERROR;
    }

    if ((textPtr->wrapMode != tkTextCharUid)
            && (textPtr->wrapMode != tkTextNoneUid)
            && (textPtr->wrapMode != tkTextWordUid)) {
        Tcl_AppendResult(interp, "bad wrap mode \"", textPtr->state,
                "\":  must be char, none, or word", (char *) NULL);
        textPtr->wrapMode = tkTextCharUid;
        return TCL_ERROR;
    }

    Tk_SetBackgroundFromBorder(textPtr->tkwin, textPtr->border);
    Tk_SetInternalBorder(textPtr->tkwin, textPtr->borderWidth);
    Tk_GeometryRequest(textPtr->tkwin, 200, 100);

    /*
     * Make sure that configuration options are properly mirrored
     * between the widget record and the "sel" tags.  NOTE: we don't
     * have to free up information during the mirroring;  old
     * information was freed when it was replaced in the widget
     * record.
     */

    textPtr->selTagPtr->border = textPtr->selBorder;
    textPtr->selTagPtr->borderWidth = textPtr->selBorderWidth;
    textPtr->selTagPtr->fgColor = textPtr->selFgColorPtr;

    /*
     * Claim the selection if we've suddenly started exporting it and there
     * are tagged characters.
     */

    if (textPtr->exportSelection && (!oldExport)) {
        TkTextSearch search;

        TkBTreeStartSearch(textPtr->tree, 0, 0, TkBTreeNumLines(textPtr->tree),
                0, textPtr->selTagPtr, &search);
        if (TkBTreeNextTag(&search)) {
            Tk_OwnSelection(textPtr->tkwin, TkTextLostSelection,
                    (ClientData) textPtr);
            textPtr->flags |= GOT_SELECTION;
        }
    }

    /*
     * Register the desired geometry for the window, and arrange for
     * the window to be redisplayed.
     */

    if (textPtr->width <= 0) {
        textPtr->width = 1;
    }
    if (textPtr->height <= 0) {
        textPtr->height = 1;
    }
    charWidth = XTextWidth(textPtr->fontPtr, "0", 1);
    charHeight = (textPtr->fontPtr->ascent + textPtr->fontPtr->descent);
    Tk_GeometryRequest(textPtr->tkwin,
            textPtr->width * charWidth + 2*textPtr->borderWidth
                    + 2*textPtr->padX,
            textPtr->height * charHeight + 2*textPtr->borderWidth
                    + 2*textPtr->padX);
    Tk_SetInternalBorder(textPtr->tkwin, textPtr->borderWidth);
    if (textPtr->setGrid) {
        Tk_SetGrid(textPtr->tkwin, textPtr->width, textPtr->height,
                charWidth, charHeight);
    }

    TkTextRelayoutWindow(textPtr);
    return TCL_OK;
}
\f
/*
 *--------------------------------------------------------------
 *
 * TextEventProc --
 *
 *      This procedure is invoked by the Tk dispatcher on
 *      structure changes to a text.  For texts with 3D
 *      borders, this procedure is also invoked for exposures.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      When the window gets deleted, internal structures get
 *      cleaned up.  When it gets exposed, it is redisplayed.
 *
 *--------------------------------------------------------------
 */

static void
TextEventProc(clientData, eventPtr)
    ClientData clientData;      /* Information about window. */
    register XEvent *eventPtr;  /* Information about event. */
{
    register TkText *textPtr = (TkText *) clientData;

    if (eventPtr->type == Expose) {
        TkTextRedrawRegion(textPtr, eventPtr->xexpose.x,
                eventPtr->xexpose.y, eventPtr->xexpose.width,
                eventPtr->xexpose.height);
    } else if (eventPtr->type == ConfigureNotify) {
        if ((textPtr->prevWidth != Tk_Width(textPtr->tkwin))
                || (textPtr->prevHeight != Tk_Height(textPtr->tkwin))) {
            TkTextRelayoutWindow(textPtr);
        }
    } else if (eventPtr->type == DestroyNotify) {
        Tcl_DeleteCommand(textPtr->interp, Tk_PathName(textPtr->tkwin));
        textPtr->tkwin = NULL;
        Tk_EventuallyFree((ClientData) textPtr, DestroyText);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * InsertChars --
 *
 *      This procedure implements most of the functionality of the
 *      "insert" widget command.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The characters in "string" get added to the text just before
 *      the character indicated by "line" and "ch".
 *
 *----------------------------------------------------------------------
 */

static void
InsertChars(textPtr, line, ch, string)
    TkText *textPtr;            /* Overall information about text widget. */
    int line, ch;               /* Identifies character just before which
                                 * new information is to be inserted. */
    char *string;               /* Null-terminated string containing new
                                 * information to add to text. */
{
    register TkTextLine *linePtr;

    /*
     * Locate the line where the insertion will occur.
     */

    linePtr = TkTextRoundIndex(textPtr, &line, &ch);

    /*
     * Notify the display module that lines are about to change, then do
     * the insertion.
     */

    TkTextLinesChanged(textPtr, line, line);
    TkBTreeInsertChars(textPtr->tree, linePtr, ch, string);

    /*
     * If the line containing the insertion point was textPtr->topLinePtr,
     * we must reset this pointer since the line structure was re-allocated.
     */

    if (linePtr == textPtr->topLinePtr) {
        TkTextSetView(textPtr, line, 0);
    }

    /*
     * Invalidate any selection retrievals in progress.
     */

    textPtr->selOffset = -1;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * DeleteChars --
 *
 *      This procedure implements most of the functionality of the
 *      "delete" widget command.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static void
DeleteChars(textPtr, line1, ch1, line2, ch2)
    TkText *textPtr;            /* Overall information about text widget. */
    int line1, ch1;             /* Position of first character to delete. */
    int line2, ch2;             /* Position of character just after last
                                 * one to delete. */
{
    register TkTextLine *line1Ptr, *line2Ptr;
    int numLines, topLine;

    /*
     * The loop below is needed because a LeaveNotify event may be
     * generated on the current charcter if it's about to be deleted.
     * If this happens, then the bindings that trigger could modify
     * the text, invalidating the range information computed here.
     * So, go back and recompute all the range information after
     * synthesizing a leave event.
     */

    while (1) {

        /*
         * Locate the starting and ending lines for the deletion and adjust
         * the endpoints if necessary to ensure that they are within valid
         * ranges.  Adjust the deletion range if necessary to ensure that the
         * text (and each invidiual line) always ends in a newline.
         */
    
        numLines = TkBTreeNumLines(textPtr->tree);
        line1Ptr = TkTextRoundIndex(textPtr, &line1, &ch1);
        if (line2 < 0) {
            return;
        } else if (line2 >= numLines) {
            line2 = numLines-1;
            line2Ptr = TkBTreeFindLine(textPtr->tree, line2);
            ch2 = line2Ptr->numBytes;
        } else {
            line2Ptr = TkBTreeFindLine(textPtr->tree, line2);
            if (ch2 < 0) {
                ch2 = 0;
            }
        }
    
        /*
         * If the deletion range ends after the last character of a line,
         * do one of three things:
         *
         * (a) if line2Ptr isn't the last line of the text, just adjust the
         *     ending point to be just before the 0th character of the next
         *     line.
         * (b) if ch1 is at the beginning of a line, then adjust line1Ptr and
         *     ch1 to point just after the last character of the previous line.
         * (c) otherwise, adjust ch2 so the final newline isn't deleted.
         */
    
        if (ch2 >= line2Ptr->numBytes) {
            if (line2 < (numLines-1)) {
                line2++;
                line2Ptr = TkBTreeNextLine(line2Ptr);
                ch2 = 0;
            } else {
                ch2 = line2Ptr->numBytes-1;
                if ((ch1 == 0) && (line1 > 0)) {
                    line1--;
                    line1Ptr = TkBTreeFindLine(textPtr->tree, line1);
                    ch1 = line1Ptr->numBytes;
                    ch2 = line2Ptr->numBytes;
                } else {
                    ch2 = line2Ptr->numBytes-1;
                }
            }
        }

        if ((line1 > line2) || ((line1 == line2) && (ch1 >= ch2))) {
            return;
        }

        /*
         * If the current character is within the range being deleted,
         * unpick it and synthesize a leave event for its tags, then
         * go back and recompute the range ends.
         */

        if (!(textPtr->flags & IN_CURRENT)) {
            break;
        }
        if ((textPtr->currentAnnotPtr->linePtr == line1Ptr)
                && (textPtr->currentAnnotPtr->ch < ch1)) {
            break;
        }
        if ((textPtr->currentAnnotPtr->linePtr == line2Ptr)
                && (textPtr->currentAnnotPtr->ch >= ch2)) {
            break;
        }
        if (line2 > (line1+1)) {
            int currentLine;

            currentLine = TkBTreeLineIndex(textPtr->currentAnnotPtr->linePtr);
            if ((currentLine <= line1) || (currentLine >= line2)) {
                break;
            }
        }
        TkTextUnpickCurrent(textPtr);
    }

    /*
     * Tell the display what's about to happen so it can discard
     * obsolete display information, then do the deletion.  Also,
     * check to see if textPtr->topLinePtr is in the range of
     * characters deleted.  If so, call the display module to reset
     * it after doing the deletion.
     */

    topLine = TkBTreeLineIndex(textPtr->topLinePtr);
    TkTextLinesChanged(textPtr, line1, line2);
    TkBTreeDeleteChars(textPtr->tree, line1Ptr, ch1, line2Ptr, ch2);
    if ((topLine >= line1) && (topLine <= line2)) {
        numLines = TkBTreeNumLines(textPtr->tree);
        TkTextSetView(textPtr, (line1 > (numLines-1)) ? (numLines-1) : line1,
                0);
    }

    /*
     * Invalidate any selection retrievals in progress.
     */

    textPtr->selOffset = -1;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TextFetchSelection --
 *
 *      This procedure is called back by Tk when the selection is
 *      requested by someone.  It returns part or all of the selection
 *      in a buffer provided by the caller.
 *
 * 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
TextFetchSelection(clientData, offset, buffer, maxBytes)
    ClientData clientData;              /* Information about text widget. */
    int offset;                         /* 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. */
{
    register TkText *textPtr = (TkText *) clientData;
    register TkTextLine *linePtr;
    int count, chunkSize;
    TkTextSearch search;

    if (!textPtr->exportSelection) {
        return -1;
    }

    /*
     * Find the beginning of the next range of selected text.  Note:  if
     * the selection is being retrieved in multiple pieces (offset != 0)
     * and some modification has been made to the text that affects the
     * selection (textPtr->selOffset != offset) then reject the selection
     * request (make 'em start over again).
     */

    if (offset == 0) {
        textPtr->selLine = 0;
        textPtr->selCh = 0;
        textPtr->selOffset = 0;
    } else if (textPtr->selOffset != offset) {
        return 0;
    }
    TkBTreeStartSearch(textPtr->tree, textPtr->selLine, textPtr->selCh+1,
            TkBTreeNumLines(textPtr->tree), 0, textPtr->selTagPtr, &search);
    if (!TkBTreeCharTagged(search.linePtr, textPtr->selCh,
            textPtr->selTagPtr)) {
        if (!TkBTreeNextTag(&search)) {
            if (offset == 0) {
                return -1;
            } else {
                return 0;
            }
        }
        textPtr->selLine = search.line1;
        textPtr->selCh = search.ch1;
    }

    /*
     * Each iteration through the outer loop below scans one selected range.
     * Each iteration through the nested loop scans one line in the
     * selected range.
     */

    count = 0;
    while (1) {
        linePtr = search.linePtr;

        /*
         * Find the end of the current range of selected text.
         */

        if (!TkBTreeNextTag(&search)) {
            panic("TextFetchSelection couldn't find end of range");
        }

        /*
         * Copy information from text lines into the buffer until
         * either we run out of space in the buffer or we get to
         * the end of this range of text.
         */

        while (1) {
            chunkSize = ((linePtr == search.linePtr) ? search.ch1
                    : linePtr->numBytes) - textPtr->selCh;
            if (chunkSize > maxBytes) {
                chunkSize = maxBytes;
            }
            memcpy((VOID *) buffer, (VOID *) (linePtr->bytes + textPtr->selCh),
                    chunkSize);
            buffer += chunkSize;
            maxBytes -= chunkSize;
            count += chunkSize;
            textPtr->selOffset += chunkSize;
            if (maxBytes == 0) {
                textPtr->selCh += chunkSize;
                goto done;
            }
            if (linePtr == search.linePtr) {
                break;
            }
            textPtr->selCh = 0;
            textPtr->selLine++;
            linePtr = TkBTreeNextLine(linePtr);
        }

        /*
         * Find the beginning of the next range of selected text.
         */

        if (!TkBTreeNextTag(&search)) {
            break;
        }
        textPtr->selLine = search.line1;
        textPtr->selCh = search.ch1;
    }

    done:
    *buffer = 0;
    return count;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkTextLostSelection --
 *
 *      This procedure is called back by Tk when the selection is
 *      grabbed away from a text widget.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The "sel" tag is cleared from the window.
 *
 *----------------------------------------------------------------------
 */

void
TkTextLostSelection(clientData)
    ClientData clientData;              /* Information about text widget. */
{
    register TkText *textPtr = (TkText *) clientData;

    if (!textPtr->exportSelection) {
        return;
    }

    /*
     * Just remove the "sel" tag from everything in the widget.
     */

    TkTextRedrawTag(textPtr, 0, 0, TkBTreeNumLines(textPtr->tree),
            0, textPtr->selTagPtr, 1);
    TkBTreeTag(textPtr->tree, 0, 0, TkBTreeNumLines(textPtr->tree),
            0, textPtr->selTagPtr, 0);
    textPtr->flags &= ~GOT_SELECTION;
}
\f
/*
 *--------------------------------------------------------------
 *
 * TextMarkCmd --
 *
 *      This procedure is invoked to process the "mark" options of
 *      the widget command for text widgets. See the user documentation
 *      for details on what it does.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *--------------------------------------------------------------
 */

static int
TextMarkCmd(textPtr, interp, argc, argv)
    register TkText *textPtr;   /* Information about text widget. */
    Tcl_Interp *interp;         /* Current interpreter. */
    int argc;                   /* Number of arguments. */
    char **argv;                /* Argument strings.  Someone else has already
                                 * parsed this command enough to know that
                                 * argv[1] is "mark". */
{
    int length, line, ch, i;
    char c;
    Tcl_HashEntry *hPtr;
    TkAnnotation *markPtr;
    Tcl_HashSearch search;

    if (argc < 3) {
        Tcl_AppendResult(interp, "wrong # args: should be \"",
                argv[0], " mark option ?arg arg ...?\"", (char *) NULL);
        return TCL_ERROR;
    }
    c = argv[2][0];
    length = strlen(argv[2]);
    if ((c == 'n') && (strncmp(argv[2], "names", length) == 0)) {
        if (argc != 3) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " mark names\"", (char *) NULL);
            return TCL_ERROR;
        }
        for (hPtr = Tcl_FirstHashEntry(&textPtr->markTable, &search);
                hPtr != NULL; hPtr = Tcl_NextHashEntry(&search)) {
            Tcl_AppendElement(interp,
                    Tcl_GetHashKey(&textPtr->markTable, hPtr), 0);
        }
    } else if ((c == 's') && (strncmp(argv[2], "set", length) == 0)) {
        if (argc != 5) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " mark set markName index\"", (char *) NULL);
            return TCL_ERROR;
        }
        if (TkTextGetIndex(interp, textPtr, argv[4], &line, &ch) != TCL_OK) {
            return TCL_ERROR;
        }
        TkTextSetMark(textPtr, argv[3], line, ch);
    } else if ((c == 'u') && (strncmp(argv[2], "unset", length) == 0)) {
        if (argc < 4) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " mark unset markName ?markName ...?\"",
                    (char *) NULL);
            return TCL_ERROR;
        }
        for (i = 3; i < argc; i++) {
            hPtr = Tcl_FindHashEntry(&textPtr->markTable, argv[i]);
            if (hPtr != NULL) {
                markPtr = (TkAnnotation *) Tcl_GetHashValue(hPtr);
                if (markPtr == textPtr->insertAnnotPtr) {
                    interp->result = "can't delete \"insert\" mark";
                    return TCL_ERROR;
                }
                if (markPtr == textPtr->currentAnnotPtr) {
                    interp->result = "can't delete \"current\" mark";
                    return TCL_ERROR;
                }
                TkBTreeRemoveAnnotation(markPtr);
                Tcl_DeleteHashEntry(hPtr);
                ckfree((char *) markPtr);
            }
        }
    } else {
        Tcl_AppendResult(interp, "bad mark option \"", argv[2],
                "\":  must be names, set, or unset",
                (char *) NULL);
        return TCL_ERROR;
    }
    return TCL_OK;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TkTextSetMark --
 *
 *      Set a mark to a particular position, creating a new mark if
 *      one doesn't already exist.
 *
 * Results:
 *      The return value is a pointer to the mark that was just set.
 *
 * Side effects:
 *      A new mark is created, or an existing mark is moved.
 *
 *----------------------------------------------------------------------
 */

TkAnnotation *
TkTextSetMark(textPtr, name, line, ch)
    TkText *textPtr;            /* Text widget in which to create mark. */
    char *name;                 /* Name of mark to set. */
    int line;                   /* Index of line at which to place mark. */
    int ch;                     /* Index of character within line at which
                                 * to place mark. */
{
    Tcl_HashEntry *hPtr;
    TkAnnotation *markPtr;
    int new;

    hPtr = Tcl_CreateHashEntry(&textPtr->markTable, name, &new);
    markPtr = (TkAnnotation *) Tcl_GetHashValue(hPtr);
    if (!new) {
        /*
         * If this is the insertion point that's being moved, be sure
         * to force a display update at the old position.
         */

        if (markPtr == textPtr->insertAnnotPtr) {
            int oldLine;

            oldLine = TkBTreeLineIndex(markPtr->linePtr);
            TkTextLinesChanged(textPtr, oldLine, oldLine);
        }
        TkBTreeRemoveAnnotation(markPtr);
    } else {
        markPtr = (TkAnnotation *) ckalloc(sizeof(TkAnnotation));
        markPtr->type = TK_ANNOT_MARK;
        markPtr->info.hPtr = hPtr;
        Tcl_SetHashValue(hPtr, markPtr);
    }
    if (line < 0) {
        line = 0;
        markPtr->ch = 0;
    } else if (ch < 0) {
        markPtr->ch = 0;
    } else {
        markPtr->ch = ch;
    }
    markPtr->linePtr = TkBTreeFindLine(textPtr->tree, line);
    if (markPtr->linePtr == NULL) {
        line = TkBTreeNumLines(textPtr->tree)-1;
        markPtr->linePtr = TkBTreeFindLine(textPtr->tree, line);
        markPtr->ch = markPtr->linePtr->numBytes-1;
    } else {
        if (markPtr->ch >= markPtr->linePtr->numBytes) {
            TkTextLine *nextLinePtr;

            nextLinePtr = TkBTreeNextLine(markPtr->linePtr);
            if (nextLinePtr == NULL) {
                markPtr->ch = markPtr->linePtr->numBytes-1;
            } else {
                markPtr->linePtr = nextLinePtr;
                line++;
                markPtr->ch = 0;
            }
        }
    }
    TkBTreeAddAnnotation(markPtr);

    /*
     * If the mark is the insertion cursor, then update the screen at the
     * mark's new location.
     */

    if (markPtr == textPtr->insertAnnotPtr) {
        TkTextLinesChanged(textPtr, line, line);
    }
    return markPtr;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TextBlinkProc --
 *
 *      This procedure is called as a timer handler to blink the
 *      insertion cursor off and on.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The cursor gets turned on or off, redisplay gets invoked,
 *      and this procedure reschedules itself.
 *
 *----------------------------------------------------------------------
 */

static void
TextBlinkProc(clientData)
    ClientData clientData;      /* Pointer to record describing text. */
{
    register TkText *textPtr = (TkText *) clientData;
    int lineNum;

    if (!(textPtr->flags & GOT_FOCUS) || (textPtr->insertOffTime == 0)) {
        return;
    }
    if (textPtr->flags & INSERT_ON) {
        textPtr->flags &= ~INSERT_ON;
        textPtr->insertBlinkHandler = Tk_CreateTimerHandler(
                textPtr->insertOffTime, TextBlinkProc, (ClientData) textPtr);
    } else {
        textPtr->flags |= INSERT_ON;
        textPtr->insertBlinkHandler = Tk_CreateTimerHandler(
                textPtr->insertOnTime, TextBlinkProc, (ClientData) textPtr);
    }
    lineNum = TkBTreeLineIndex(textPtr->insertAnnotPtr->linePtr);
    TkTextLinesChanged(textPtr, lineNum, lineNum);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * TextFocusProc --
 *
 *      This procedure is called whenever the entry gets or loses the
 *      input focus.  It's also called whenever the window is reconfigured
 *      while it has the focus.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The cursor gets turned on or off.
 *
 *----------------------------------------------------------------------
 */

static void
TextFocusProc(clientData, gotFocus)
    ClientData clientData;      /* Pointer to structure describing text. */
    int gotFocus;               /* 1 means window is getting focus, 0 means
                                 * it's losing it. */
{
    register TkText *textPtr = (TkText *) clientData;
    int lineNum;

    Tk_DeleteTimerHandler(textPtr->insertBlinkHandler);
    if (gotFocus) {
        textPtr->flags |= GOT_FOCUS | INSERT_ON;
        if (textPtr->insertOffTime != 0) {
            textPtr->insertBlinkHandler = Tk_CreateTimerHandler(
                    textPtr->insertOnTime, TextBlinkProc,
                    (ClientData) textPtr);
        }
    } else {
        textPtr->flags &= ~(GOT_FOCUS | INSERT_ON);
        textPtr->insertBlinkHandler = (Tk_TimerToken) NULL;
    }
    lineNum = TkBTreeLineIndex(textPtr->insertAnnotPtr->linePtr);
    TkTextLinesChanged(textPtr, lineNum, lineNum);
}
\f
/*
 *--------------------------------------------------------------
 *
 * TextScanCmd --
 *
 *      This procedure is invoked to process the "scan" options of
 *      the widget command for text widgets. See the user documentation
 *      for details on what it does.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *--------------------------------------------------------------
 */

static int
TextScanCmd(textPtr, interp, argc, argv)
    register TkText *textPtr;   /* Information about text widget. */
    Tcl_Interp *interp;         /* Current interpreter. */
    int argc;                   /* Number of arguments. */
    char **argv;                /* Argument strings.  Someone else has already
                                 * parsed this command enough to know that
                                 * argv[1] is "tag". */
{
    int length, y, line, lastLine;
    char c;

    if (argc != 4) {
        Tcl_AppendResult(interp, "wrong # args: should be \"",
                argv[0], " scan mark|dragto y\"", (char *) NULL);
        return TCL_ERROR;
    }
    if (Tcl_GetInt(interp, argv[3], &y) != TCL_OK) {
        return TCL_ERROR;
    }
    c = argv[2][0];
    length = strlen(argv[2]);
    if ((c == 'd') && (strncmp(argv[2], "dragto", length) == 0)) {
        /*
         * Amplify the difference between the current y position and the
         * mark position to compute how many lines up or down the view
         * should shift, then update the mark position to correspond to
         * the new view.  If we run off the top or bottom of the text,
         * reset the mark point so that the current position continues
         * to correspond to the edge of the window.  This means that the
         * picture will start dragging as soon as the mouse reverses
         * direction (without this reset, might have to slide mouse a
         * long ways back before the picture starts moving again).
         */

        line = textPtr->scanMarkLine + (10*(textPtr->scanMarkY - y))
                / (textPtr->fontPtr->ascent + textPtr->fontPtr->descent);
        lastLine = TkBTreeNumLines(textPtr->tree) - 1;
        if (line < 0) {
            textPtr->scanMarkLine = line = 0;
            textPtr->scanMarkY = y;
        } else if (line > lastLine) {
            textPtr->scanMarkLine = line = lastLine;
            textPtr->scanMarkY = y;
        }
        TkTextSetView(textPtr, line, 0);
    } else if ((c == 'm') && (strncmp(argv[2], "mark", length) == 0)) {
        textPtr->scanMarkLine = TkBTreeLineIndex(textPtr->topLinePtr);
        textPtr->scanMarkY = y;
    } else {
        Tcl_AppendResult(interp, "bad scan option \"", argv[2],
                "\":  must be mark or dragto", (char *) NULL);
        return TCL_ERROR;
    }
    return TCL_OK;
}