Splits layout: Allow setting the split_axis option to auto so that all new windows have their split axis chosen automatically unless explicitly specified in the launch command

Fixes #7887

docs/changelog.rst

@@ -93,6 +93,8 @@ Detailed list of changes
 
 - Remote control: Fix ``--match state:self`` not working (:disc:`7886`)
 
+- Splits layout: Allow setting the ``split_axis`` option to ``auto`` so that all new windows have their split axis chosen automatically unless explicitly specified in the launch command (:iss:`7887`)
+
 0.36.2 [2024-09-06]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

docs/layouts.rst

@@ -184,11 +184,13 @@ in a split using the ``rotate`` action with an argument of ``180`` and rotate
 and swap with an argument of ``270``.
 
 This layout takes one option, ``split_axis`` that controls whether new windows
-are placed into vertical or horizontal splits when a :option:`--location <launch
+are placed into vertical or horizontal splits when a :option:`--location
---location>` is not specified. A value of ``horizontal`` (same as
+<launch --location>` is not specified. A value of ``horizontal`` (same as
-``--location=vsplit``) means when a new split is created the two windows will be
+``--location=vsplit``) means when a new split is created the two windows will
-placed side by side and a value of ``vertical`` (same as ``--location=hsplit``)
+be placed side by side and a value of ``vertical`` (same as
-means the two windows will be placed one on top of the other. By default::
+``--location=hsplit``) means the two windows will be placed one on top of the
+other. A value of ``auto`` means the axis of the split is chosen automatically
+(same as ``--location=split``). By default::
 
     enabled_layouts splits:split_axis=horizontal
 

kitty/layout/splits.py

@@ -423,10 +423,14 @@ class Pair:
 
 class SplitsLayoutOpts(LayoutOpts):
 
-    default_axis_is_horizontal: bool = True
+    default_axis_is_horizontal: bool | None = True
 
     def __init__(self, data: Dict[str, str]):
-        self.default_axis_is_horizontal = data.get('split_axis', 'horizontal') == 'horizontal'
+        q = data.get('split_axis', 'horizontal')
+        if q == 'auto':
+            self.default_axis_is_horizontal = None
+        else:
+            self.default_axis_is_horizontal = q == 'horizontal'
 
     def serialized(self) -> Dict[str, Any]:
         return {'default_axis_is_horizontal': self.default_axis_is_horizontal}
@@ -439,14 +443,17 @@ class Splits(Layout):
     no_minimal_window_borders = True
 
     @property
-    def default_axis_is_horizontal(self) -> bool:
+    def default_axis_is_horizontal(self) -> bool | None:
         return self.layout_opts.default_axis_is_horizontal
 
     @property
     def pairs_root(self) -> Pair:
         root: Optional[Pair] = getattr(self, '_pairs_root', None)
         if root is None:
-            self._pairs_root = root = Pair(horizontal=self.default_axis_is_horizontal)
+            horizontal = self.default_axis_is_horizontal
+            if horizontal is None:
+                horizontal = True
+            self._pairs_root = root = Pair(horizontal=horizontal)
         return root
 
     @pairs_root.setter
@@ -508,7 +515,7 @@ class Splits(Layout):
             group_id = ag.id
             pair = self.pairs_root.pair_for_window(group_id)
             if pair is not None:
-                if location == 'split':
+                if location == 'split' or horizontal is None:
                     wwidth = aw.geometry.right - aw.geometry.left
                     wheight = aw.geometry.bottom - aw.geometry.top
                     horizontal = wwidth >= wheight