button to load the default preset 2

data/key-mapper.glade

@@ -483,7 +483,7 @@
               </packing>
             </child>
             <child>
-              <object class="GtkButton" id="apply_defaults">
+              <object class="GtkButton" id="apply_system_layout">
                 <property name="label" translatable="yes">Apply Defaults</property>
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
@@ -494,7 +494,7 @@
                 <property name="margin_bottom">10</property>
                 <property name="border_width">0</property>
                 <property name="image">gtk-redo-icon-2</property>
-                <signal name="clicked" handler="on_apply_defaults_clicked" swapped="no"/>
+                <signal name="clicked" handler="on_apply_system_layout_clicked" swapped="no"/>
               </object>
               <packing>
                 <property name="expand">False</property>

keymapper/X.py

@@ -164,23 +164,48 @@ def apply_preset(device, preset):
     setxkbmap(device, layout)
 
 
+def get_system_layout():
+    """Get the system wide configured default keyboard layout."""
+    localectl = subprocess.check_output(
+        ['localectl', 'status']
+    ).decode().split('\n')
+    # example:
+    # System Locale: LANG=en_GB.UTF-8
+    # VC Keymap: tmp
+    # X11 Layout: de
+    # X11 Model: pc105
+    return [
+        line for line in localectl
+        if 'X11 Layout' in line
+    ][0].split(': ')[-1]
+
+
 def setxkbmap(device, layout):
     """Apply a preset to the device.
 
     Parameters
     ----------
     device : string
-    layout : string
-        For example 'de', passed to setxkbmap unmodified
+    layout : string or None
+        For example 'de', passed to setxkbmap unmodified. If None, will
+        load the system default
     """
-    with open(os.path.join(X11_SYMBOLS, layout), 'r') as f:
-        if f.read() == '':
-            logger.error('Tried to load empty config')
+    if layout is not None:
+        path = os.path.join(X11_SYMBOLS, layout)
+        if not os.path.exists(path):
+            logger.error('Symbols %s don\'t exist', path)
             return
+        with open(path, 'r') as f:
+            if f.read() == '':
+                logger.error('Tried to load empty symbols %s', path)
+                return
 
     logger.info('Applying layout "%s" on device %s', layout, device)
     group = get_devices()[device]
 
+    keycodes = None if layout is None else 'key-mapper'
+    layout = layout or get_system_layout()
+
     # apply it to every device that hangs on the same usb port, because I
     # have no idea how to figure out which one of those 3 devices that are
     # all named after my mouse to use.
@@ -191,10 +216,13 @@ def setxkbmap(device, layout):
 
         cmd = [
             'setxkbmap',
-            '-layout', layout,
-            '-keycodes', 'key-mapper',
             '-device', str(xinput_id)
         ]
+        if layout is not None:
+            cmd += ['-layout', layout]
+        if keycodes is not None:
+            cmd += ['-keycodes', keycodes]
+
         logger.debug('Running `%s`', ' '.join(cmd))
         subprocess.run(cmd)
 

keymapper/gtk/window.py

@@ -29,8 +29,7 @@ from gi.repository import Gtk, Gdk, GLib
 
 from keymapper.data import get_data_path
 from keymapper.X import create_setxkbmap_config, apply_preset, \
-    create_preset, custom_mapping, parse_symbols_file, setxkbmap, \
-    DEFAULT_SYMBOLS_NAME
+    create_preset, custom_mapping, parse_symbols_file, setxkbmap
 from keymapper.presets import get_presets, find_newest_preset, \
     delete_preset, rename_preset
 from keymapper.logger import logger
@@ -171,9 +170,9 @@ class Window:
         key_list.forall(key_list.remove)
         custom_mapping.empty()
 
-    def on_apply_defaults_clicked(self, button):
-        """Load the mapping that was known to be used before key-mapper."""
-        setxkbmap(self.selected_device, DEFAULT_SYMBOLS_NAME)
+    def on_apply_system_layout_clicked(self, button):
+        """Load the mapping."""
+        setxkbmap(self.selected_device, None)
 
     def on_save_preset_clicked(self, button):
         """Save changes to a preset to the file system."""

tests/testcases/X.py

@@ -0,0 +1,39 @@
+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+# key-mapper - GUI for device specific keyboard mappings
+# Copyright (C) 2020 sezanzeb <proxima@hip70890b.de>
+#
+# This file is part of key-mapper.
+#
+# key-mapper is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# key-mapper is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with key-mapper.  If not, see <https://www.gnu.org/licenses/>.
+
+
+import re
+import unittest
+
+from keymapper.X import get_system_layout
+
+
+class Test(unittest.TestCase):
+    def test_get_system_layout(self):
+        layout = get_system_layout()
+        self.assertGreater(len(layout), 0)
+        # should be all alphanumeric
+        match = re.findall(r'\w+', layout)
+        self.assertEqual(len(match), 1)
+        self.assertEqual(match[0], layout)
+
+
+if __name__ == "__main__":
+    unittest.main()