Function refreshMultiLine

tools/shell/linenoise.cpp:2269–2440

Multi line low level line refresh. * * Rewrite the currently edited line accordingly to the buffer content, * cursor position, and number of columns of the terminal. */

 * Rewrite the currently edited line accordingly to the buffer content,
 * cursor position, and number of columns of the terminal. */
static void refreshMultiLine(struct linenoiseState* l) {
    if (!l->render) {
        return;
    }
    char seq[64];
    int plen = linenoiseComputeRenderWidth(l->prompt, strlen(l->prompt));
    // utf8 in prompt, get render width
    size_t rows, cols;
    int new_cursor_row, new_cursor_x;
    positionToColAndRow(l->pos, new_cursor_row, new_cursor_x, rows, cols, l);
    int col; /* colum position, zero-based. */
    int old_rows = l->maxrows ? l->maxrows : 1;
    int fd = l->ofd;
    auto render_buf = l->buf;
    auto render_len = l->len;
    uint64_t render_start = 0;
    uint64_t render_end = render_len;
    if (l->clear_screen) {
        l->oldpos = 0;
        old_rows = 0;
        l->clear_screen = false;
    }
    if (rows > l->rows) {
        // the text does not fit in the terminal (too many rows)
        // enable scrolling mode
        // check if, given the current y_scroll, the cursor is visible
        // display range is [y_scroll, y_scroll + l->rows]
        if (new_cursor_row < int(l->y_scroll) + 1) {
            l->y_scroll = new_cursor_row - 1;
        } else if (new_cursor_row > int(l->y_scroll) + int(l->rows)) {
            l->y_scroll = new_cursor_row - l->rows;
        }
        // display only characters up to the current scroll position
        if (l->y_scroll == 0) {
            render_start = 0;
        } else {
            render_start = colAndRowToPosition(l->y_scroll, 0, l);
        }
        if (l->y_scroll + l->rows >= rows) {
            render_end = l->len;
        } else {
            render_end = colAndRowToPosition(l->y_scroll + l->rows, 99999, l);
        }
        new_cursor_row -= l->y_scroll;
        render_buf += render_start;
        render_len = render_end - render_start;
        lndebug("truncate to rows %d - %d (render bytes %d to %d)", l->y_scroll,
            l->y_scroll + l->rows, render_start, render_end);
        rows = l->rows;
    } else {
        l->y_scroll = 0;
    }

    /* Update maxrows if needed. */
    if (rows > l->maxrows) {
        l->maxrows = rows;
    }