Add a new `last_used_layout` function that can be mapped to a shortcut to switch to the previously used window layout

Fixes #870

docs/changelog.rst

@@ -3,6 +3,13 @@ Changelog
 
 |kitty| is a feature full, cross-platform, *fast*, GPU based terminal emulator.
 
+0.12.2 [future]
+------------------------------
+
+- Add a new ``last_used_layout`` function that can be mapped to a shortcut to
+  switch to the previously used window layout (:iss:`870`)
+
+
 0.12.1 [2018-09-08]
 ------------------------------
 

kitty/cmds.py

@@ -282,7 +282,7 @@ def set_tab_title(boss, window, payload):
 # }}}
 
 
-# set_layout {{{
+# goto_layout {{{
 @cmd(
     'Set the window layout',
     'Set the window layout in the specified tab (or the active tab if not specified).'
@@ -317,6 +317,34 @@ def goto_layout(boss, window, payload):
 # }}}
 
 
+# last_used_layout {{{
+@cmd(
+    'Switch to the last used layout',
+    'Switch to the last used window layout in the specified tab (or the active tab if not specified).'
+    ' You can use special match value :italic:`all` to set the layout in all tabs.',
+    options_spec=MATCH_TAB_OPTION,
+)
+def cmd_last_used_layout(global_opts, opts, args):
+    return {'match': opts.match}
+
+
+def last_used_layout(boss, window, payload):
+    match = payload['match']
+    if match:
+        if match == 'all':
+            tabs = tuple(boss.all_tabs)
+        else:
+            tabs = tuple(boss.match_tabs(match))
+        if not tabs:
+            raise MatchError(match, 'tabs')
+    else:
+        tabs = [boss.tab_for_window(window) if window else boss.active_tab]
+    for tab in tabs:
+        if tab:
+            tab.last_used_layout()
+# }}}
+
+
 # close_window {{{
 @cmd(
     'Close the specified window(s)',

kitty/config_data.py

@@ -155,6 +155,11 @@ You can also create shortcuts to switch to specific layouts::
 
     map ctrl+alt+t goto_layout tall
     map ctrl+alt+s goto_layout stack
+
+Similarly, to switch back to the previous layout::
+
+   map ctrl+alt+p last_used_layout
+
 ''')],
     'shortcuts.fonts': [
         _('Font sizes'), _('''\

kitty/tabs.py

@@ -46,10 +46,11 @@ class Tab:  # {{{
         self.windows = deque()
         for i, which in enumerate('first second third fourth fifth sixth seventh eighth ninth tenth'.split()):
             setattr(self, which + '_window', partial(self.nth_window, num=i))
+        self._last_used_layout = self._current_layout_name = None
         if session_tab is None:
             self.cwd = self.args.directory
             sl = self.enabled_layouts[0]
-            self.current_layout = self.create_layout_object(sl)
+            self._set_current_layout(sl)
             if special_window is None:
                 self.new_window(cwd_from=cwd_from)
             else:
@@ -57,9 +58,14 @@ class Tab:  # {{{
         else:
             self.cwd = session_tab.cwd or self.args.directory
             l0 = session_tab.layout
-            self.current_layout = self.create_layout_object(l0)
+            self._set_current_layout(l0)
             self.startup(session_tab)
 
+    def _set_current_layout(self, layout_name):
+        self._last_used_layout = self._current_layout_name
+        self.current_layout = self.create_layout_object(layout_name)
+        self._current_layout_name = layout_name
+
     def startup(self, session_tab):
         for cmd in session_tab.windows:
             if isinstance(cmd, (SpecialWindowInstance,)):
@@ -154,7 +160,12 @@ class Tab:  # {{{
             else:
                 idx = -1
             nl = self.enabled_layouts[(idx + 1) % len(self.enabled_layouts)]
-            self.current_layout = self.create_layout_object(nl)
+            self._set_current_layout(nl)
+            self.relayout()
+
+    def last_used_layout(self):
+        if len(self.enabled_layouts) > 1 and self._last_used_layout and self._last_used_layout != self._current_layout_name:
+            self._set_current_layout(self._last_used_layout)
             self.relayout()
 
     def goto_layout(self, layout_name, raise_exception=False):
@@ -164,7 +175,7 @@ class Tab:  # {{{
                 raise ValueError(layout_name)
             log_error('Unknown or disabled layout: {}'.format(layout_name))
             return
-        self.current_layout = self.create_layout_object(layout_name)
+        self._set_current_layout(layout_name)
         self.relayout()
 
     def resize_window_by(self, window_id, increment, is_horizontal):