curses and use_default_colors()

Discussion in 'Python' started by Brian Victor, Jul 29, 2003.

  1. Brian Victor

    Brian Victor Guest

    I am attempting to write a curses-based program. I would like to use
    the default terminal background rather than a black one (a significant
    difference with transluscent terminals, regardless of one's opinion of

    It appears that in the C ncurses interface, this is accomplished via
    use_default_colors() and assume_default_colors(). However, these
    functions don't seem to have parallels in the python binding. Is there
    some way to accomplish what I want?

    Brian Victor, Jul 29, 2003
    1. Advertisements

  2. Brian Victor

    Chris Reay Guest


    I don't know how much this'll help, but my home-brewed curses TextApp
    class has a white-on-blue default, and TextApp.startWin() contains
    these lines (inter alia) ...

    # ... blah, blah, blah.
    curses.init_pair(1, curses.COLOR_WHITE, curses.COLOR_BLUE)
    # ... blah, blah, blah ...
    self.scrn = self.stdscr.subwin(self.height, self.width, 0, 0)
    # Blah, blah, blah ...


    Chris Reay, Jul 30, 2003
    1. Advertisements

  3. Brian Victor

    Brian Victor Guest


    Thanks, but that's not quite what I'm looking for. Getting a solid
    background isn't a problem. Getting a subtly textured background to
    show through (or other windows on Mac) seems to be a bit tricker.

    Still hoping someone will hop in with "just use this curses extension"
    or "you can write a wrapper around that one function and integrate it
    with python's curses like this." But thanks for the input, anyway!
    Brian Victor, Jul 30, 2003
  4. Brian Victor

    Brian Victor Guest

    I guess that someone is me. I love replying to my own posts...

    I just hacked this bit of code up and it seems to do the trick.
    importing usedefault and calling usedefault.use_default_colors() sets
    color pair 0 to use the default colors for the terminal. This allows
    translucency on terminals that support it. The packaging could use some
    work, but the following should be enough to get future readers going.

    This is the first C extension I've written, and it's almost straight
    from the docs. If anyone has any pointers, I'd be happy to hear them.

    #include <Python.h>
    #include <ncurses.h>

    static PyObject *
    pyuse_default_colors(PyObject *self, PyObject *args)
    return Py_None;

    static PyMethodDef SpamMethods[] = {
    {"use_default_colors", pyuse_default_colors, METH_VARARGS,
    "Use Default Colors."},
    {NULL, NULL, 0, NULL} /* Sentinel */

    /* PyMODINIT_FUNC */
    /* The docs say to use the above, but it doesn't exist in my copy of
    * Python.h. */
    void initusedefault()
    (void) Py_InitModule("usedefault", SpamMethods);
    from distutils.core import setup, Extension

    module1 = Extension('usedefault',
    libraries = ["ncurses"],
    sources = ['usedefault.c'])

    setup (name = 'usedefault',
    version = '1.0',
    description = 'Use default colors in curses',
    ext_modules = [module1])
    Brian Victor, Jul 30, 2003
  5. Use METH_NOARGS instead of METH_VARARGS; as written, this code will accept
    any number of arguments to the Python use_default_colors() method and not
    raise any error. An alternative would be to leave METH_VARARGS and put "if
    (!PyArg_NoArgs(args)) return NULL;" in pyuse_default_colors(); this would
    work with older versions of Python at the cost of being slightly slower.

    I'll add this function to the curses module, so at least it'll be in 2.4;
    thanks for writing it. Anyone know if it's possible to test it on MacOS X?
    Does the Terminal support transparency?

    A.M. Kuchling, Jul 31, 2003
  6. Brian Victor

    Brian Victor Guest

    I forgot to mention that I hit a compile error on OSX's ncurses header
    file. I believe it came from the December dev tools. It dealt with
    redefining wchar_t:

    #ifndef _WCHAR_T
    typedef unsigned long wchar_t;
    #endif /* _WCHAR_T */

    I have no idea why the mac version does that (fink's does also). My
    linux copy of the headers has nothing like that. #defining _WCHAR_T
    before including ncurses.h fixed that, but I don't know if that's a
    permanent solution. FWIW, I was doing this with python 2.3a1.
    Brian Victor, Aug 1, 2003
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.