macos: add key binding for equalizing split sizes

macos/Sources/AppDelegate.swift

@@ -38,6 +38,7 @@ class AppDelegate: NSObject, ObservableObject, NSApplicationDelegate, GhosttyApp
     @IBOutlet private var menuResetFontSize: NSMenuItem?
     @IBOutlet private var menuTerminalInspector: NSMenuItem?
 
+    @IBOutlet private var menuEqualizeSplits: NSMenuItem?
     @IBOutlet private var menuMoveSplitDividerUp: NSMenuItem?
     @IBOutlet private var menuMoveSplitDividerDown: NSMenuItem?
     @IBOutlet private var menuMoveSplitDividerLeft: NSMenuItem?
@@ -215,6 +216,7 @@ class AppDelegate: NSObject, ObservableObject, NSApplicationDelegate, GhosttyApp
         syncMenuShortcut(action: "resize_split:down,10", menuItem: self.menuMoveSplitDividerDown)
         syncMenuShortcut(action: "resize_split:right,10", menuItem: self.menuMoveSplitDividerRight)
         syncMenuShortcut(action: "resize_split:left,10", menuItem: self.menuMoveSplitDividerLeft)
+        syncMenuShortcut(action: "equalize_splits", menuItem: self.menuEqualizeSplits)
 
         syncMenuShortcut(action: "increase_font_size:1", menuItem: self.menuIncreaseFontSize)
         syncMenuShortcut(action: "decrease_font_size:1", menuItem: self.menuDecreaseFontSize)

macos/Sources/Features/Terminal/TerminalController.swift

@@ -271,6 +271,11 @@ class TerminalController: NSWindowController, NSWindowDelegate,
         splitMoveFocus(direction: .right)
     }
 
+    @IBAction func equalizeSplits(_ sender: Any) {
+        guard let surface = focusedSurface?.surface else { return }
+        ghostty.splitEqualize(surface: surface)
+    }
+
     @IBAction func moveSplitDividerUp(_ sender: Any) {
         guard let surface = focusedSurface?.surface else { return }
         ghostty.splitResize(surface: surface, direction: .up, amount: 10)

macos/Sources/Ghostty/AppState.swift

@@ -160,6 +160,8 @@ extension Ghostty {
                 focus_split_cb: { userdata, direction in AppState.focusSplit(userdata, direction: direction) },
                 resize_split_cb: { userdata, direction, amount in
                     AppState.resizeSplit(userdata, direction: direction, amount: amount) },
+                equalize_splits_cb: { userdata in
+                    AppState.equalizeSplits(userdata) },
                 toggle_split_zoom_cb: { userdata in AppState.toggleSplitZoom(userdata) },
                 goto_tab_cb: { userdata, n in AppState.gotoTab(userdata, n: n) },
                 toggle_fullscreen_cb: { userdata, nonNativeFullscreen in AppState.toggleFullscreen(userdata, nonNativeFullscreen: nonNativeFullscreen) },
@@ -298,6 +300,10 @@ extension Ghostty {
             ghostty_surface_split_resize(surface, direction.toNative(), amount)
         }
 
+        func splitEqualize(surface: ghostty_surface_t) {
+            ghostty_surface_split_equalize(surface)
+        }
+
         func splitToggleZoom(surface: ghostty_surface_t) {
             let action = "toggle_split_zoom"
             if (!ghostty_surface_binding_action(surface, action, UInt(action.count))) {
@@ -383,6 +389,11 @@ extension Ghostty {
             )
         }
 
+        static func equalizeSplits(_ userdata: UnsafeMutableRawPointer?) {
+            guard let surface = self.surfaceUserdata(from: userdata) else { return }
+            NotificationCenter.default.post(name: Notification.didEqualizeSplits, object: surface)
+        }
+
         static func toggleSplitZoom(_ userdata: UnsafeMutableRawPointer?) {
             guard let surface = self.surfaceUserdata(from: userdata) else { return }
 

macos/Sources/Ghostty/Ghostty.SplitNode.swift

@@ -171,7 +171,31 @@ extension Ghostty {
                 }
             }
 
-            
+            /// Equalize the splits in this container. Each split is equalized
+            /// based on its weight, i.e. the number of leaves it contains.
+            /// This function returns the weight of this container.
+            func equalize() -> UInt {
+                let topLeftWeight: UInt
+                switch (topLeft) {
+                case .leaf:
+                    topLeftWeight = 1
+                case .split(let c):
+                    topLeftWeight = c.equalize()
+                }
+
+                let bottomRightWeight: UInt
+                switch (bottomRight) {
+                case .leaf:
+                    bottomRightWeight = 1
+                case .split(let c):
+                    bottomRightWeight = c.equalize()
+                }
+
+                let weight = topLeftWeight + bottomRightWeight
+                split = Double(topLeftWeight) / Double(weight)
+                return weight
+            }
+
             // MARK: - Hashable
             
             func hash(into hasher: inout Hasher) {

macos/Sources/Ghostty/Ghostty.TerminalSplit.swift

@@ -50,6 +50,7 @@ extension Ghostty {
         var body: some View {
             let center = NotificationCenter.default
             let pubZoom = center.publisher(for: Notification.didToggleSplitZoom)
+            let pubEqualize = center.publisher(for: Notification.didEqualizeSplits)
 
             // If we're zoomed, we don't render anything, we are transparent. This
             // ensures that the View stays around so we don't lose our state, but
@@ -75,6 +76,7 @@ extension Ghostty {
                             container: container
                         )
                         .onReceive(pubZoom) { onZoom(notification: $0) }
+                        .onReceive(pubEqualize) { onEqualize(notification: $0) }
                     }
                 }
                 .navigationTitle(surfaceTitle ?? "Ghostty")
@@ -135,8 +137,18 @@ extension Ghostty {
                 }
             }
         }
+
+        func onEqualize(notification: SwiftUI.Notification) {
+            // If there are no splits then there is nothing to do
+            switch (node) {
+            case .split(let c):
+                _ = c.equalize()
+            default:
+                return
+            }
+        }
     }
-    
+
     /// A noSplit leaf node of a split tree.
     private struct TerminalSplitLeaf: View {
         /// The leaf to draw the surface for.

macos/Sources/Ghostty/Package.swift

@@ -150,6 +150,9 @@ extension Ghostty.Notification {
     static let didResizeSplit = Notification.Name("com.mitchellh.ghostty.didResizeSplit")
     static let ResizeSplitDirectionKey = didResizeSplit.rawValue + ".direction"
     static let ResizeSplitAmountKey = didResizeSplit.rawValue + ".amount"
+
+    /// Notification sent to the split root to equalize split sizes
+    static let didEqualizeSplits = Notification.Name("com.mitchellh.ghostty.didEqualizeSplits")
 }
 
 // Make the input enum hashable.

macos/Sources/MainMenu.xib

@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="22155" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES" customObjectInstantitationMethod="direct">
+<document type="com.apple.InterfaceBuilder3.Cocoa.XIB" version="3.0" toolsVersion="22154" targetRuntime="MacOSX.Cocoa" propertyAccessControl="none" useAutolayout="YES" customObjectInstantitationMethod="direct">
     <dependencies>
         <deployment identifier="macosx"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="22155"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.CocoaPlugin" version="22154"/>
     </dependencies>
     <objects>
         <customObject id="-2" userLabel="File's Owner" customClass="NSApplication">
@@ -18,6 +18,7 @@
                 <outlet property="menuCloseWindow" destination="W5w-UZ-crk" id="6ff-BT-ENV"/>
                 <outlet property="menuCopy" destination="Jqf-pv-Zcu" id="bKd-1C-oy9"/>
                 <outlet property="menuDecreaseFontSize" destination="kzb-SZ-dOA" id="Y1B-Vh-6Z2"/>
+                <outlet property="menuEqualizeSplits" destination="3gH-VD-vL9" id="SiZ-ce-FOF"/>
                 <outlet property="menuIncreaseFontSize" destination="CIH-ey-Z6x" id="hkc-9C-80E"/>
                 <outlet property="menuMoveSplitDividerDown" destination="Zj7-2W-fdF" id="997-LL-nlN"/>
                 <outlet property="menuMoveSplitDividerLeft" destination="wSR-ny-j1a" id="HCZ-CI-2ob"/>
@@ -270,6 +271,13 @@
                                 <modifierMask key="keyEquivalentModifierMask"/>
                                 <menu key="submenu" title="Resize Split" id="t7T-Ti-0im">
                                     <items>
+                                        <menuItem title="Equalize Splits" id="3gH-VD-vL9">
+                                            <modifierMask key="keyEquivalentModifierMask"/>
+                                            <connections>
+                                                <action selector="equalizeSplits:" target="-1" id="RE0-hS-YLf"/>
+                                            </connections>
+                                        </menuItem>
+                                        <menuItem isSeparatorItem="YES" id="XKA-Jd-h9t"/>
                                         <menuItem title="Move Divider Up" id="h9Y-40-3oo">
                                             <modifierMask key="keyEquivalentModifierMask"/>
                                             <connections>