textbox.c

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/*
 *  textbox.c -- implements the text box
 *
 *  ORIGINAL AUTHOR: Savio Lam (lam836@cs.cuhk.hk)
 *  MODIFIED FOR LINUX KERNEL CONFIG BY: William Roadcap (roadcap@cfw.com)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "dialog.h"

static void back_lines (int n);
static void print_page (WINDOW * win, int height, int width);
static void print_line (WINDOW * win, int row, int width);
static char *get_line (void);
static void print_position (WINDOW * win, int height, int width);

static int hscroll = 0, fd, file_size, bytes_read;
static int begin_reached = 1, end_reached = 0, page_length;
static char *buf, *page;

/*
 * Display text from a file in a dialog box.
 */
int
dialog_textbox (const char *title, const char *file, int height, int width)
{
    int i, x, y, cur_x, cur_y, fpos, key = 0;
    int passed_end;
    char search_term[MAX_LEN + 1];
    WINDOW *dialog, *text;

    search_term[0] = '\0';      /* no search term entered yet */

    /* Open input file for reading */
    if ((fd = open (file, O_RDONLY)) == -1) {
        endwin ();
        fprintf (stderr,
                 "\nCan't open input file in dialog_textbox().\n");
        exit (-1);
    }
    /* Get file size. Actually, 'file_size' is the real file size - 1,
       since it's only the last byte offset from the beginning */
    if ((file_size = lseek (fd, 0, SEEK_END)) == -1) {
        endwin ();
        fprintf (stderr, "\nError getting file size in dialog_textbox().\n");
        exit (-1);
    }
    /* Restore file pointer to beginning of file after getting file size */
    if (lseek (fd, 0, SEEK_SET) == -1) {
        endwin ();
        fprintf (stderr, "\nError moving file pointer in dialog_textbox().\n");
        exit (-1);
    }
    /* Allocate space for read buffer */
    if ((buf = malloc (BUF_SIZE + 1)) == NULL) {
        endwin ();
        fprintf (stderr, "\nCan't allocate memory in dialog_textbox().\n");
        exit (-1);
    }
    if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
        endwin ();
        fprintf (stderr, "\nError reading file in dialog_textbox().\n");
        exit (-1);
    }
    buf[bytes_read] = '\0';     /* mark end of valid data */
    page = buf;                 /* page is pointer to start of page to be displayed */

    /* center dialog box on screen */
    x = (COLS - width) / 2;
    y = (LINES - height) / 2;


    draw_shadow (stdscr, y, x, height, width);

    dialog = newwin (height, width, y, x);
    keypad (dialog, TRUE);

    /* Create window for text region, used for scrolling text */
    text = subwin (dialog, height - 4, width - 2, y + 1, x + 1);
    wattrset (text, dialog_attr);
    wbkgdset (text, dialog_attr & A_COLOR);

    keypad (text, TRUE);

    /* register the new window, along with its borders */
    draw_box (dialog, 0, 0, height, width, dialog_attr, border_attr);

    wattrset (dialog, border_attr);
    mvwaddch (dialog, height-3, 0, ACS_LTEE);
    for (i = 0; i < width - 2; i++)
        waddch (dialog, ACS_HLINE);
    wattrset (dialog, dialog_attr);
    wbkgdset (dialog, dialog_attr & A_COLOR);
    waddch (dialog, ACS_RTEE);

    if (title != NULL && strlen(title) >= width-2 ) {
        /* truncate long title -- mec */
        char * title2 = malloc(width-2+1);
        memcpy( title2, title, width-2 );
        title2[width-2] = '\0';
        title = title2;
    }

    if (title != NULL) {
        wattrset (dialog, title_attr);
        mvwaddch (dialog, 0, (width - strlen(title))/2 - 1, ' ');
        waddstr (dialog, (char *)title);
        waddch (dialog, ' ');
    }
    print_button (dialog, " Exit ", height - 2, width / 2 - 4, TRUE);
    wnoutrefresh (dialog);
    getyx (dialog, cur_y, cur_x);       /* Save cursor position */

    /* Print first page of text */
    attr_clear (text, height - 4, width - 2, dialog_attr);
    print_page (text, height - 4, width - 2);
    print_position (dialog, height, width);
    wmove (dialog, cur_y, cur_x);       /* Restore cursor position */
    wrefresh (dialog);

    while ((key != ESC) && (key != '\n')) {
        key = wgetch (dialog);
        switch (key) {
        case 'E':               /* Exit */
        case 'e':
        case 'X':
        case 'x':
            delwin (dialog);
            free (buf);
            close (fd);
            return 0;
        case 'g':               /* First page */
        case KEY_HOME:
            if (!begin_reached) {
                begin_reached = 1;
                /* First page not in buffer? */
                if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
                    endwin ();
                    fprintf (stderr,
                      "\nError moving file pointer in dialog_textbox().\n");
                    exit (-1);
                }
                if (fpos > bytes_read) {        /* Yes, we have to read it in */
                    if (lseek (fd, 0, SEEK_SET) == -1) {
                        endwin ();
                        fprintf (stderr, "\nError moving file pointer in "
                                 "dialog_textbox().\n");
                        exit (-1);
                    }
                    if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                        endwin ();
                        fprintf (stderr,
                             "\nError reading file in dialog_textbox().\n");
                        exit (-1);
                    }
                    buf[bytes_read] = '\0';
                }
                page = buf;
                print_page (text, height - 4, width - 2);
                print_position (dialog, height, width);
                wmove (dialog, cur_y, cur_x);   /* Restore cursor position */
                wrefresh (dialog);
            }
            break;
        case 'G':               /* Last page */
        case KEY_END:

            end_reached = 1;
            /* Last page not in buffer? */
            if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
                endwin ();
                fprintf (stderr,
                      "\nError moving file pointer in dialog_textbox().\n");
                exit (-1);
            }
            if (fpos < file_size) {     /* Yes, we have to read it in */
                if (lseek (fd, -BUF_SIZE, SEEK_END) == -1) {
                    endwin ();
                    fprintf (stderr,
                      "\nError moving file pointer in dialog_textbox().\n");
                    exit (-1);
                }
                if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                    endwin ();
                    fprintf (stderr,
                             "\nError reading file in dialog_textbox().\n");
                    exit (-1);
                }
                buf[bytes_read] = '\0';
            }
            page = buf + bytes_read;
            back_lines (height - 4);
            print_page (text, height - 4, width - 2);
            print_position (dialog, height, width);
            wmove (dialog, cur_y, cur_x);       /* Restore cursor position */
            wrefresh (dialog);
            break;
        case 'K':               /* Previous line */
        case 'k':
        case KEY_UP:
            if (!begin_reached) {
                back_lines (page_length + 1);

                /* We don't call print_page() here but use scrolling to ensure
                   faster screen update. However, 'end_reached' and
                   'page_length' should still be updated, and 'page' should
                   point to start of next page. This is done by calling
                   get_line() in the following 'for' loop. */
                scrollok (text, TRUE);
                wscrl (text, -1);       /* Scroll text region down one line */
                scrollok (text, FALSE);
                page_length = 0;
                passed_end = 0;
                for (i = 0; i < height - 4; i++) {
                    if (!i) {
                        /* print first line of page */
                        print_line (text, 0, width - 2);
                        wnoutrefresh (text);
                    } else
                        /* Called to update 'end_reached' and 'page' */
                        get_line ();
                    if (!passed_end)
                        page_length++;
                    if (end_reached && !passed_end)
                        passed_end = 1;
                }

                print_position (dialog, height, width);
                wmove (dialog, cur_y, cur_x);   /* Restore cursor position */
                wrefresh (dialog);
            }
            break;
        case 'B':               /* Previous page */
        case 'b':
        case KEY_PPAGE:
            if (begin_reached)
                break;
            back_lines (page_length + height - 4);
            print_page (text, height - 4, width - 2);
            print_position (dialog, height, width);
            wmove (dialog, cur_y, cur_x);
            wrefresh (dialog);
            break;
        case 'J':               /* Next line */
        case 'j':
        case KEY_DOWN:
            if (!end_reached) {
                begin_reached = 0;
                scrollok (text, TRUE);
                scroll (text);  /* Scroll text region up one line */
                scrollok (text, FALSE);
                print_line (text, height - 5, width - 2);
                wnoutrefresh (text);
                print_position (dialog, height, width);
                wmove (dialog, cur_y, cur_x);   /* Restore cursor position */
                wrefresh (dialog);
            }
            break;
        case KEY_NPAGE:         /* Next page */
        case ' ':
            if (end_reached)
                break;

            begin_reached = 0;
            print_page (text, height - 4, width - 2);
            print_position (dialog, height, width);
            wmove (dialog, cur_y, cur_x);
            wrefresh (dialog);
            break;
        case '0':               /* Beginning of line */
        case 'H':               /* Scroll left */
        case 'h':
        case KEY_LEFT:
            if (hscroll <= 0)
                break;

            if (key == '0')
                hscroll = 0;
            else
                hscroll--;
            /* Reprint current page to scroll horizontally */
            back_lines (page_length);
            print_page (text, height - 4, width - 2);
            wmove (dialog, cur_y, cur_x);
            wrefresh (dialog);
            break;
        case 'L':               /* Scroll right */
        case 'l':
        case KEY_RIGHT:
            if (hscroll >= MAX_LEN)
                break;
            hscroll++;
            /* Reprint current page to scroll horizontally */
            back_lines (page_length);
            print_page (text, height - 4, width - 2);
            wmove (dialog, cur_y, cur_x);
            wrefresh (dialog);
            break;
        case ESC:
            break;
        }
    }

    delwin (dialog);
    free (buf);
    close (fd);
    return -1;                  /* ESC pressed */
}

/*
 * Go back 'n' lines in text file. Called by dialog_textbox().
 * 'page' will be updated to point to the desired line in 'buf'.
 */
static void
back_lines (int n)
{
    int i, fpos;

    begin_reached = 0;
    /* We have to distinguish between end_reached and !end_reached
       since at end of file, the line is not ended by a '\n'.
       The code inside 'if' basically does a '--page' to move one
       character backward so as to skip '\n' of the previous line */
    if (!end_reached) {
        /* Either beginning of buffer or beginning of file reached? */
        if (page == buf) {
            if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
                endwin ();
                fprintf (stderr, "\nError moving file pointer in "
                         "back_lines().\n");
                exit (-1);
            }
            if (fpos > bytes_read) {    /* Not beginning of file yet */
                /* We've reached beginning of buffer, but not beginning of
                   file yet, so read previous part of file into buffer.
                   Note that we only move backward for BUF_SIZE/2 bytes,
                   but not BUF_SIZE bytes to avoid re-reading again in
                   print_page() later */
                /* Really possible to move backward BUF_SIZE/2 bytes? */
                if (fpos < BUF_SIZE / 2 + bytes_read) {
                    /* No, move less then */
                    if (lseek (fd, 0, SEEK_SET) == -1) {
                        endwin ();
                        fprintf (stderr, "\nError moving file pointer in "
                                 "back_lines().\n");
                        exit (-1);
                    }
                    page = buf + fpos - bytes_read;
                } else {        /* Move backward BUF_SIZE/2 bytes */
                    if (lseek (fd, -(BUF_SIZE / 2 + bytes_read), SEEK_CUR)
                        == -1) {
                        endwin ();
                        fprintf (stderr, "\nError moving file pointer "
                                 "in back_lines().\n");
                        exit (-1);
                    }
                    page = buf + BUF_SIZE / 2;
                }
                if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                    endwin ();
                    fprintf (stderr, "\nError reading file in back_lines().\n");
                    exit (-1);
                }
                buf[bytes_read] = '\0';
            } else {            /* Beginning of file reached */
                begin_reached = 1;
                return;
            }
        }
        if (*(--page) != '\n') {        /* '--page' here */
            /* Something's wrong... */
            endwin ();
            fprintf (stderr, "\nInternal error in back_lines().\n");
            exit (-1);
        }
    }
    /* Go back 'n' lines */
    for (i = 0; i < n; i++)
        do {
            if (page == buf) {
                if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
                    endwin ();
                    fprintf (stderr,
                          "\nError moving file pointer in back_lines().\n");
                    exit (-1);
                }
                if (fpos > bytes_read) {
                    /* Really possible to move backward BUF_SIZE/2 bytes? */
                    if (fpos < BUF_SIZE / 2 + bytes_read) {
                        /* No, move less then */
                        if (lseek (fd, 0, SEEK_SET) == -1) {
                            endwin ();
                            fprintf (stderr, "\nError moving file pointer "
                                     "in back_lines().\n");
                            exit (-1);
                        }
                        page = buf + fpos - bytes_read;
                    } else {    /* Move backward BUF_SIZE/2 bytes */
                        if (lseek (fd, -(BUF_SIZE / 2 + bytes_read),
                                   SEEK_CUR) == -1) {
                            endwin ();
                            fprintf (stderr, "\nError moving file pointer"
                                     " in back_lines().\n");
                            exit (-1);
                        }
                        page = buf + BUF_SIZE / 2;
                    }
                    if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                        endwin ();
                        fprintf (stderr, "\nError reading file in "
                                 "back_lines().\n");
                        exit (-1);
                    }
                    buf[bytes_read] = '\0';
                } else {        /* Beginning of file reached */
                    begin_reached = 1;
                    return;
                }
            }
        } while (*(--page) != '\n');
    page++;
}

/*
 * Print a new page of text. Called by dialog_textbox().
 */
static void
print_page (WINDOW * win, int height, int width)
{
    int i, passed_end = 0;

    page_length = 0;
    for (i = 0; i < height; i++) {
        print_line (win, i, width);
        if (!passed_end)
            page_length++;
        if (end_reached && !passed_end)
            passed_end = 1;
    }
    wnoutrefresh (win);
}

/*
 * Print a new line of text. Called by dialog_textbox() and print_page().
 */
static void
print_line (WINDOW * win, int row, int width)
{
    int y, x;
    char *line;

    line = get_line ();
    line += MIN (strlen (line), hscroll);       /* Scroll horizontally */
    wmove (win, row, 0);        /* move cursor to correct line */
    waddch (win, ' ');
    waddnstr (win, line, MIN (strlen (line), width - 2));

    getyx (win, y, x);
    /* Clear 'residue' of previous line */
#if OLD_NCURSES
    {
        int i;
        for (i = 0; i < width - x; i++)
            waddch (win, ' ');
    }
#else
    wclrtoeol(win);
#endif
}

/*
 * Return current line of text. Called by dialog_textbox() and print_line().
 * 'page' should point to start of current line before calling, and will be
 * updated to point to start of next line.
 */
static char *
get_line (void)
{
    int i = 0, fpos;
    static char line[MAX_LEN + 1];

    end_reached = 0;
    while (*page != '\n') {
        if (*page == '\0') {
            /* Either end of file or end of buffer reached */
            if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
                endwin ();
                fprintf (stderr, "\nError moving file pointer in "
                         "get_line().\n");
                exit (-1);
            }
            if (fpos < file_size) {     /* Not end of file yet */
                /* We've reached end of buffer, but not end of file yet,
                   so read next part of file into buffer */
                if ((bytes_read = read (fd, buf, BUF_SIZE)) == -1) {
                    endwin ();
                    fprintf (stderr, "\nError reading file in get_line().\n");
                    exit (-1);
                }
                buf[bytes_read] = '\0';
                page = buf;
            } else {
                if (!end_reached)
                    end_reached = 1;
                break;
            }
        } else if (i < MAX_LEN)
            line[i++] = *(page++);
        else {
            /* Truncate lines longer than MAX_LEN characters */
            if (i == MAX_LEN)
                line[i++] = '\0';
            page++;
        }
    }
    if (i <= MAX_LEN)
        line[i] = '\0';
    if (!end_reached)
        page++;                 /* move pass '\n' */

    return line;
}

/*
 * Print current position
 */
static void
print_position (WINDOW * win, int height, int width)
{
    int fpos, percent;

    if ((fpos = lseek (fd, 0, SEEK_CUR)) == -1) {
        endwin ();
        fprintf (stderr, "\nError moving file pointer in print_position().\n");
        exit (-1);
    }
    wattrset (win, position_indicator_attr);
    wbkgdset (win, position_indicator_attr & A_COLOR);
    percent = !file_size ?
        100 : ((fpos - bytes_read + page - buf) * 100) / file_size;
    wmove (win, height - 3, width - 9);
    wprintw (win, "(%3d%%)", percent);
}

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