Make Layer shifting two-dimensional

src/button.rs

@@ -29,12 +29,24 @@ pub enum Button {
     Key(Key),
     ModTap(Key, Modifier),
     Compose(Key, Key, Option<Key>),
-    NextLayer,
-    PrevLayer,
-    HoldLayer(u16),
+    Layer(LayerShift, LayerDir, u16),
     None,
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub enum LayerDir {
+    Left,
+    Right,
+    Up,
+    Down,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub enum LayerShift {
+    Move,
+    Peek,
+}
+
 impl Display for Button {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
@@ -43,9 +55,7 @@ impl Display for Button {
             Button::ModTap(key, modifier) => write!(f, "{key:?}/{modifier}"),
             Button::Compose(k1, k2, None) => write!(f, "⎄ {k1:?} {k2:?}"),
             Button::Compose(k1, k2, Some(k3)) => write!(f, "⎄ {k1:?} {k2:?} {k3:?}"),
-            Button::NextLayer => write!(f, "↘"),
-            Button::PrevLayer => write!(f, "↖"),
-            Button::HoldLayer(layer) => write!(f, "HL{layer}"),
+            Button::Layer(..) => write!(f, "Lr"),
             Button::None => write!(f, "Ø"),
         }
     }