How to change mouse wheel scroll speed per application

Question

Is it possible to have different mouse wheel scroll speed based on application running on top (focused).

Like slower scroll speed for guake for easy reading and higher for web browser to scroll faster.

Answer 1

Introduction

The following script dynamic_mouse_speed.py allows specifying what mouse pointer and/or scroll speed should be when user-defined window has focus.

Important: the script requires imwheel program to increase scrolling speed. Please install it via sudo apt-get install imwheel

Usage

As shown by -h flag:

usage: dynamic_mouse_speed.py [-h] [-q] [-p POINTER] [-s SCROLL] [-v]

Sets mouse pointer and scroll speed per window

optional arguments:
  -h, --help            show this help message and exit
  -q, --quiet           Blocks GUI dialogs.
  -p POINTER, --pointer POINTER
                        mouse pointer speed,floating point number from -1 to 1
  -s SCROLL, --scroll SCROLL
                        mouse scroll speed,integer value , -10 to 10
                        recommended
  -v, --verbose         prints debugging information on command line

The script allows user to select the window they want to track with mouse click. The mouse pointer will turn into cross and user can select a window they want.

Running python3 dynamic_mouse_speed.py alone only shows popup dialog and does nothing by itself.

Running python3 dynamic_mouse_speed.py -s 5 increases scroll speed, while python3 dynamic_mouse_speed.py -s -5 slows scroll speed down. python3 dynamic_mouse_speed.py -p -0.9 decreases pointer speed, while python3 dynamic_mouse_speed.py -p 0.9 increases pointer speed. -s and -p options can be mixed. -v produces debugging information on command line.

Source

Also available as GitHub gist

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Author: Sergiy Kolodyazhnyy
Date:  August 2nd, 2016
Written for: https://askubuntu.com/q/806212/295286
Tested on Ubuntu 16.04 LTS

usage: dynamic_mouse_speed.py [-h] [-q] [-p POINTER] [-s SCROLL] [-v]

Sets mouse pointer and scroll speed per window

optional arguments:
  -h, --help            show this help message and exit
  -q, --quiet           Blocks GUI dialogs.
  -p POINTER, --pointer POINTER
                        mouse pointer speed,floating point number from -1 to 1
  -s SCROLL, --scroll SCROLL
                        mouse scroll speed,integer value , -10 to 10
                        recommended
  -v, --verbose         prints debugging information on command line


"""
from __future__ import print_function
import gi
gi.require_version('Gdk', '3.0')
gi.require_version('Gtk', '3.0')
from gi.repository import Gdk, Gtk,Gio
import time
import subprocess
import sys
import os
import argparse


def run_cmd(cmdlist):
    """ Reusable function for running shell commands"""
    try:
        stdout = subprocess.check_output(cmdlist)
    except subprocess.CalledProcessError:
        print(">>> subprocess:",cmdlist)
        sys.exit(1)
    else:
        if stdout:
            return stdout



def get_user_window():
    """Select two windows via mouse. 
       Returns integer value of window's id"""
    window_id = None
    while not window_id:
        for line in run_cmd(['xwininfo', '-int']).decode().split('\n'):
            if 'Window id:' in line:
                window_id = line.split()[3]
    return int(window_id)

def gsettings_get(schema,path,key):
    """Get value of gsettings schema"""
    if path is None:
        gsettings = Gio.Settings.new(schema)
    else:
        gsettings = Gio.Settings.new_with_path(schema,path)
    return gsettings.get_value(key)

def gsettings_set(schema,path,key,value):
    """Set value of gsettings schema"""
    if path is None:
        gsettings = Gio.Settings.new(schema)
    else:
        gsettings = Gio.Settings.new_with_path(schema,path)
    return gsettings.set_double(key,value)

def parse_args():
    """ Parse command line arguments"""
    arg_parser = argparse.ArgumentParser(
                 description="""Sets mouse pointer and scroll """ + 
                             """speed per window """)
    arg_parser.add_argument(
                '-q','--quiet', action='store_true',
                help='Blocks GUI dialogs.',
                required=False)

    arg_parser.add_argument(
                '-p','--pointer',action='store',
                type=float, help=' mouse pointer speed,' + 
                'floating point number from -1 to 1', required=False)

    arg_parser.add_argument(
                '-s','--scroll',action='store',
                type=int, help=' mouse scroll speed,' + 
                'integer value , -10 to 10 recommended', required=False)

    arg_parser.add_argument(
                '-v','--verbose', action='store_true',
                help=' prints debugging information on command line',
                required=False)
    return arg_parser.parse_args()

def get_mouse_id():
    """ returns id of the mouse as understood by
        xinput command. This works only with one
        mouse attatched to the system"""
    devs = run_cmd( ['xinput','list','--id-only']   ).decode().strip()
    for dev_id in devs.split('\n'):
        props = run_cmd( [ 'xinput','list-props', dev_id  ]   ).decode()
        if "Evdev Scrolling Distance" in props:
            return dev_id


def write_rcfile(scroll_speed):
    """ Writes out user-defined scroll speed
        to ~/.imwheelrc file. Necessary for
        speed increase"""

    number = str(scroll_speed)
    user_home = os.path.expanduser('~')
    with open( os.path.join(user_home,".imwheelrc") ,'w'  ) as rcfile:
        rcfile.write( '".*"\n' )
        rcfile.write("None, Up, Button4, " + number + "\n"   )   
        rcfile.write("None, Down, Button5, " + number + "\n")
        rcfile.write("Control_L, Up,   Control_L|Button4 \n" +
                     "Control_L, Down, Control_L|Button5 \n" +
                     "Shift_L,   Up,   Shift_L|Button4 \n" +
                     "Shift_L,   Down, Shift_L|Button5 \n" )



def set_configs(mouse_speed,scroll_speed,mouse_id):
    """ sets user-defined values
        when the desired window is in focus"""
    if mouse_speed:
        gsettings_set('org.gnome.desktop.peripherals.mouse',None, 'speed', mouse_speed)

    if scroll_speed:
       if scroll_speed > 0:
           subprocess.call(['killall','imwheel'])
           # Is it better to write config here
           # or in main ?
           write_rcfile(scroll_speed)
           subprocess.call(['imwheel'])
       else:
           prop="Evdev Scrolling Distance"
           scroll_speed = str(abs(scroll_speed))
           run_cmd(['xinput','set-prop',mouse_id,prop,scroll_speed,'1','1']) 



def set_defaults(mouse_speed,scroll_speed,mouse_id):
    """ restore values , when user-defined window
        looses focus"""
    if mouse_speed:
        gsettings_set('org.gnome.desktop.peripherals.mouse', None, 
                      'speed', mouse_speed)

    if scroll_speed:
        if scroll_speed > 0:
           subprocess.call(['killall','imwheel'])
        if scroll_speed < 0:
           prop="Evdev Scrolling Distance"
           run_cmd(['xinput','set-prop',mouse_id,prop,'1','1','1'])


def main():
    """Entry point for when program is executed directly"""
    args = parse_args()

    # Get a default configs
    # gsettings returns GVariant, but
    # setting same schema and key requires 
    # floating point number
    screen = Gdk.Screen.get_default()
    default_pointer_speed = gsettings_get('org.gnome.desktop.peripherals.mouse', 
                                          None, 
                                          'speed')
    default_pointer_speed = float(str(default_pointer_speed))


    # Ask user for values , or check if those are provided via command line
    if not args.quiet:
       text='--text="Select window to track"'
       mouse_speed = run_cmd(['zenity','--info',text])

    user_window = get_user_window() 

    scroll_speed = args.scroll    
    pointer_speed = args.pointer
    mouse_id = get_mouse_id()

    if pointer_speed: 
        if pointer_speed > 1 or pointer_speed < -1:

           run_cmd(['zenity','--error',
                    '--text="Value out of range:' + 
                    str(pointer_speed) + '"'])
           sys.exit(1)

    # ensure that we will raise the user selected window
    # and activate all the preferences 
    flag = True
    for window in screen.get_window_stack():
        if user_window == window.get_xid():
            window.focus(time.time())
            window.get_update_area()
    try:
        while True:
            time.sleep(0.25) # Necessary for script to catch active window
            if  screen.get_active_window().get_xid() == user_window:
                if flag:
                    set_configs(pointer_speed,scroll_speed,mouse_id) 
                    flag=False

            else:
               if not flag:
                  set_defaults(default_pointer_speed, scroll_speed,mouse_id)
                  flag = True

            if args.verbose: 
                print('ACTIVE WINDOW:',str(screen.get_active_window().get_xid()))
                print('MOUSE_SPEED:', str(gsettings_get(
                                          'org.gnome.desktop.peripherals.mouse',
                                           None, 'speed')))
                print('Mouse ID:',str(mouse_id))
                print("----------------------")
    except:
        print(">>> Exiting main, resetting values")
        set_defaults(default_pointer_speed,scroll_speed,mouse_id)

if __name__ == "__main__":
    main()

Notes

• multiple instances of script allow for setting speed per each separate window.
• When running from command line, popup dialogs produce the following message: Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged. These can be ignored.
• Consult How can I edit/create new launcher items in Unity by hand? for creating a launcher or desktop shortcut for this script , if you desire to launch it with double-click
• In order to link this script to a keyboard shortcut for easy access, consult How to add keyboard shortcuts?
• It is recommended to use only one mouse when script is running, since it operates on the first device that is found to have Evdev Scrolling Distance property
• Multiple instances can be started to control multiple windows, but it is not recommended for the sake of performance