button to load the default preset

data/key-mapper.glade

@@ -244,11 +244,15 @@
       <placeholder/>
     </child>
   </object>
+  <object class="GtkImage" id="gtk-redo-icon-2">
+    <property name="visible">True</property>
+    <property name="can_focus">False</property>
+    <property name="stock">gtk-redo</property>
+  </object>
   <object class="GtkWindow" id="window">
     <property name="width_request">450</property>
     <property name="can_focus">False</property>
     <property name="title" translatable="yes">Key Mapper</property>
-    <property name="default_height">280</property>
     <property name="icon_name">mouse</property>
     <signal name="delete-event" handler="on_close" swapped="no"/>
     <child>
@@ -478,6 +482,26 @@
                 <property name="position">2</property>
               </packing>
             </child>
+            <child>
+              <object class="GtkButton" id="apply_defaults">
+                <property name="label" translatable="yes">Apply Defaults</property>
+                <property name="visible">True</property>
+                <property name="can_focus">True</property>
+                <property name="receives_default">True</property>
+                <property name="tooltip_text" translatable="yes">To give your keys back their original mapping.</property>
+                <property name="halign">end</property>
+                <property name="margin_end">10</property>
+                <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"/>
+              </object>
+              <packing>
+                <property name="expand">False</property>
+                <property name="fill">False</property>
+                <property name="position">3</property>
+              </packing>
+            </child>
             <child>
               <object class="GtkSeparator">
                 <property name="visible">True</property>
@@ -486,7 +510,7 @@
               <packing>
                 <property name="expand">False</property>
                 <property name="fill">True</property>
-                <property name="position">3</property>
+                <property name="position">4</property>
               </packing>
             </child>
             <child>
@@ -505,7 +529,7 @@
               <packing>
                 <property name="expand">False</property>
                 <property name="fill">True</property>
-                <property name="position">4</property>
+                <property name="position">5</property>
               </packing>
             </child>
           </object>

keymapper/X.py

@@ -153,8 +153,32 @@ DEFAULT_SYMBOLS_NAME = get_preset_name('default')
 
 
 def apply_preset(device, preset):
-    """Apply a preset to the device."""
+    """Apply a preset to the device.
-    logger.info('Applying preset "%s" on device %s', preset, device)
+
+    Parameters
+    ----------
+    device : string
+    preset : string
+    """
+    layout = get_preset_name(device, preset)
+    setxkbmap(device, layout)
+
+
+def setxkbmap(device, layout):
+    """Apply a preset to the device.
+
+    Parameters
+    ----------
+    device : string
+    layout : string
+        For example 'de', passed to setxkbmap unmodified
+    """
+    with open(os.path.join(X11_SYMBOLS, layout), 'r') as f:
+        if f.read() == '':
+            logger.error('Tried to load empty config')
+            return
+
+    logger.info('Applying layout "%s" on device %s', layout, device)
     group = get_devices()[device]
 
     # apply it to every device that hangs on the same usb port, because I
@@ -165,15 +189,9 @@ def apply_preset(device, preset):
             # only all virtual devices of the same hardware device
             continue
 
-        layout_path = get_usr_path(device, preset)
-        with open(layout_path, 'r') as f:
-            if f.read() == '':
-                logger.error('Tried to load empty config')
-                return
-
         cmd = [
             'setxkbmap',
-            '-layout', get_preset_name(device, preset),
+            '-layout', layout,
             '-keycodes', 'key-mapper',
             '-device', str(xinput_id)
         ]
@@ -314,8 +332,8 @@ def parse_symbols_file(device, preset):
         result = re.findall(r'\n\s+?key <(.+?)>.+?\[\s+(\w+)', f.read())
         logger.debug('Found %d mappings in this preset', len(result))
         for keycode, character in result:
-            custom_mapping.changed = False
             custom_mapping.change(None, int(keycode), character)
+        custom_mapping.changed = False
 
 
 def create_default_symbols():

keymapper/gtk/unsaved.py

@@ -0,0 +1,46 @@
+#!/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/>.
+
+
+"""Error dialog."""
+
+
+import gi
+gi.require_version('Gtk', '3.0')
+gi.require_version('GLib', '2.0')
+from gi.repository import Gtk
+
+from keymapper.data import get_data_path
+
+
+CONTINUE = True
+GO_BACK = False
+
+
+def unsavedChangesDialog():
+    gladefile = get_data_path('key-mapper.glade')
+    builder = Gtk.Builder()
+    builder.add_from_file(gladefile)
+    dialog = builder.get_object('unsaved_changes')
+    dialog.show()
+    dialog.run()
+    dialog.hide()
+    # TODO do something meaningful
+    return GO_BACK

keymapper/gtk/window.py

@@ -29,12 +29,14 @@ 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
+    create_preset, custom_mapping, parse_symbols_file, setxkbmap, \
+    DEFAULT_SYMBOLS_NAME
 from keymapper.presets import get_presets, find_newest_preset, \
     delete_preset, rename_preset
 from keymapper.logger import logger
 from keymapper.linux import get_devices, keycode_reader
 from keymapper.gtk.row import Row
+from keymapper.gtk.unsaved import unsavedChangesDialog, GO_BACK
 
 
 def gtk_iteration():
@@ -169,6 +171,10 @@ 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_save_preset_clicked(self, button):
         """Save changes to a preset to the file system."""
         new_name = self.get('preset_name_input').get_text()
@@ -215,7 +221,9 @@ class Window:
 
     def on_select_device(self, dropdown):
         """List all presets, create one if none exist yet."""
-        # TODO unsaved changes dialog
+        if custom_mapping.changed:
+            if unsavedChangesDialog() == GO_BACK:
+                return
 
         device = dropdown.get_active_text()
 
@@ -231,7 +239,9 @@ class Window:
 
     def on_create_preset_clicked(self, button):
         """Create a new preset and select it."""
-        # TODO unsaved changes dialog
+        if custom_mapping.changed:
+            if unsavedChangesDialog() == GO_BACK:
+                return
 
         new_preset = create_preset(self.selected_device)
         self.get('preset_selection').append(new_preset, new_preset)
@@ -240,7 +250,9 @@ class Window:
 
     def on_select_preset(self, dropdown):
         """Show the mappings of the preset."""
-        # TODO unsaved changes dialog
+        if custom_mapping.changed:
+            if unsavedChangesDialog() == GO_BACK:
+                return
 
         self.clear_mapping_table()
 
@@ -296,3 +308,5 @@ class Window:
             self.selected_device,
             self.selected_preset
         )
+
+        custom_mapping.changed = False