Mouse wheel in python curses

Question

Does anyone know if it is possible to process the mouse wheel movements in curses? I suppose they should be the same as the arrow keys. An example would be much appreciated.

Thank you.

Answer 1

I'd guess it's system- and terminal-dependent. I wrote the following -- it just captures mouse states and prints them to the screen. I was able to receive mouse scroll events in Mac OSX using xterm. (Scrolling up registered as button 4 for me; down as button 2 -- but it didn't work using the native Terminal app.)

As will become clear if you look over this code, you have to use scr.getch() first, and test if it returns curses.KEY_MOUSE. If so, you can then call curses.getmouse(), which returns a tuple containing a device id, coordinates, and a state flag.

import curses
from contextlib import contextmanager

@contextmanager
def open_screen():
    scr = curses.initscr()
    curses.noecho()
    curses.cbreak()
    scr.keypad(1)
    try:
        yield scr
    finally:
        curses.nocbreak()
        scr.keypad(0)
        curses.echo()
        curses.endwin()

curses_mouse_states = {
    curses.BUTTON1_PRESSED: 'Button 1 Pressed', 
    curses.BUTTON1_RELEASED: 'Button 1 Released', 
    curses.BUTTON1_CLICKED: 'Button 1 Clicked',
    curses.BUTTON1_DOUBLE_CLICKED: 'Button 1 Double-Clicked',
    curses.BUTTON1_TRIPLE_CLICKED: 'Button 1 Triple-Clicked',

    curses.BUTTON2_PRESSED: 'Button 2 Pressed', 
    curses.BUTTON2_RELEASED: 'Button 2 Released', 
    curses.BUTTON2_CLICKED: 'Button 2 Clicked',
    curses.BUTTON2_DOUBLE_CLICKED: 'Button 2 Double-Clicked',
    curses.BUTTON2_TRIPLE_CLICKED: 'Button 2 Triple-Clicked',

    curses.BUTTON3_PRESSED: 'Button 3 Pressed', 
    curses.BUTTON3_RELEASED: 'Button 3 Released', 
    curses.BUTTON3_CLICKED: 'Button 3 Clicked',
    curses.BUTTON3_DOUBLE_CLICKED: 'Button 3 Double-Clicked',
    curses.BUTTON3_TRIPLE_CLICKED: 'Button 3 Triple-Clicked',

    curses.BUTTON4_PRESSED: 'Button 4 Pressed', 
    curses.BUTTON4_RELEASED: 'Button 4 Released', 
    curses.BUTTON4_CLICKED: 'Button 4 Clicked',
    curses.BUTTON4_DOUBLE_CLICKED: 'Button 4 Double-Clicked',
    curses.BUTTON4_TRIPLE_CLICKED: 'Button 4 Triple-Clicked',

    curses.BUTTON_SHIFT: 'Button Shift', 
    curses.BUTTON_CTRL: 'Button Ctrl', 
    curses.BUTTON_ALT: 'Button Alt'
}

with open_screen() as scr:
    curses.mousemask(-1)
    while True:
        c = scr.getch()
        if c == curses.KEY_MOUSE:
            mouse_state = curses.getmouse()[4]
            states = '; '.join(state_string for state, state_string 
                               in curses_mouse_states.viewitems() 
                               if mouse_state & state)
            scr.addstr(0, 0, states)
            scr.clrtoeol()
            scr.refresh()
        elif c == ord('q'):
            break