comparison mercurial/crecord.py @ 38047:dabc2237963c

crecord: fallback to text mode if diffs are too big for curses mode

crecord uses curses.newpad to create a region that we can then scroll around in
by moving the main 'screen' as a veiwport into the (probably larger than the
actual screen) pad.  Internally, at least in ncurses, pads are implemented using
windows, which have their dimensions limited to a certain size.  Depending on
compilation options for ncurses, this size might be pretty small: (signed)
short, or it might be larger ((signed) int).

crecord wants to have enough room to have all of the contents of the main area
of the chunkselector in the pad; this means that the full size with everything
expanded must be less than these (undocumented, afaict) limits.

It's not easy to write tests for this because the limits are platform- and
installation- dependent and undocumented / unqueryable, as far as I can tell.

Differential Revision: https://phab.mercurial-scm.org/D3577

38046:ee7b6fa52d9d

        curses.error
    except ImportError:
        # wcurses is not shipped on Windows by default, or python is not
        # compiled with curses
        curses = False

def checkcurses(ui):
    """Return True if the user wants to use curses

    This method returns True if curses is found (and that python is built with

    origsigtstp = sentinel = object()
    if util.safehasattr(signal, 'SIGTSTP'):
        origsigtstp = signal.getsignal(signal.SIGTSTP)
    try:
        curses.wrapper(chunkselector.main)
        if chunkselector.initerr is not None:
            raise error.Abort(chunkselector.initerr)
        # ncurses does not restore signal handler for SIGTSTP
    finally:
        if origsigtstp is not sentinel:
            signal.signal(signal.SIGTSTP, origsigtstp)
    return chunkselector.opts

    def _main(self, stdscr):
        self.stdscr = stdscr
        # error during initialization, cannot be printed in the curses
        # interface, it should be printed by the calling code
        self.initerr = None
        self.yscreensize, self.xscreensize = self.stdscr.getmaxyx()

        curses.start_color()
        try:
            curses.use_default_colors()

        self.numpadlines = self.getnumlinesdisplayed(ignorefolding=True) + 1

        try:
            self.chunkpad = curses.newpad(self.numpadlines, self.xscreensize)
        except curses.error:
            self.initerr = _('this diff is too large to be displayed')
            return
        # initialize selecteditemendline (initial start-line is 0)
        self.selecteditemendline = self.getnumlinesdisplayed(
            self.currentselecteditem, recursechildren=False)

38047:dabc2237963c

        curses.error
    except ImportError:
        # wcurses is not shipped on Windows by default, or python is not
        # compiled with curses
        curses = False

class fallbackerror(error.Abort):
    """Error that indicates the client should try to fallback to text mode."""
    # Inherits from error.Abort so that existing behavior is preserved if the
    # calling code does not know how to fallback.

def checkcurses(ui):
    """Return True if the user wants to use curses

    This method returns True if curses is found (and that python is built with

    origsigtstp = sentinel = object()
    if util.safehasattr(signal, 'SIGTSTP'):
        origsigtstp = signal.getsignal(signal.SIGTSTP)
    try:
        curses.wrapper(chunkselector.main)
        if chunkselector.initexc is not None:
            raise chunkselector.initexc
        # ncurses does not restore signal handler for SIGTSTP
    finally:
        if origsigtstp is not sentinel:
            signal.signal(signal.SIGTSTP, origsigtstp)
    return chunkselector.opts

    def _main(self, stdscr):
        self.stdscr = stdscr
        # error during initialization, cannot be printed in the curses
        # interface, it should be printed by the calling code
        self.initexc = None
        self.yscreensize, self.xscreensize = self.stdscr.getmaxyx()

        curses.start_color()
        try:
            curses.use_default_colors()

        self.numpadlines = self.getnumlinesdisplayed(ignorefolding=True) + 1

        try:
            self.chunkpad = curses.newpad(self.numpadlines, self.xscreensize)
        except curses.error:
            self.initexc = fallbackerror(
                _('this diff is too large to be displayed'))
            return
        # initialize selecteditemendline (initial start-line is 0)
        self.selecteditemendline = self.getnumlinesdisplayed(
            self.currentselecteditem, recursechildren=False)