core: add resize_split binding with default keys

On macOS, use Cmd+Ctrl+Arrow keys as default bindings for resizing by 10
points in the given direction.

src/Surface.zig

@@ -2426,6 +2426,14 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
             } else log.warn("runtime doesn't implement gotoSplit", .{});
         },
 
+        .resize_split => |param| {
+            if (@hasDecl(apprt.Surface, "resizeSplit")) {
+                const direction = param[0];
+                const amount = param[1];
+                self.rt_surface.resizeSplit(direction, amount);
+            } else log.warn("runtime doesn't implement resizeSplit", .{});
+        },
+
         .toggle_split_zoom => {
             if (@hasDecl(apprt.Surface, "toggleSplitZoom")) {
                 self.rt_surface.toggleSplitZoom();

src/config/Config.zig

@@ -956,6 +956,26 @@ pub fn default(alloc_gpa: Allocator) Allocator.Error!Config {
             .{ .key = .right, .mods = .{ .super = true, .alt = true } },
             .{ .goto_split = .right },
         );
+        try result.keybind.set.put(
+            alloc,
+            .{ .key = .up, .mods = .{ .super = true, .ctrl = true } },
+            .{ .resize_split = .{ .up, 10 } },
+        );
+        try result.keybind.set.put(
+            alloc,
+            .{ .key = .down, .mods = .{ .super = true, .ctrl = true } },
+            .{ .resize_split = .{ .down, 10 } },
+        );
+        try result.keybind.set.put(
+            alloc,
+            .{ .key = .left, .mods = .{ .super = true, .ctrl = true } },
+            .{ .resize_split = .{ .left, 10 } },
+        );
+        try result.keybind.set.put(
+            alloc,
+            .{ .key = .right, .mods = .{ .super = true, .ctrl = true } },
+            .{ .resize_split = .{ .right, 10 } },
+        );
 
         // Inspector, matching Chromium
         try result.keybind.set.put(

src/input.zig

@@ -11,6 +11,7 @@ pub const KeyEncoder = @import("input/KeyEncoder.zig");
 pub const InspectorMode = Binding.Action.InspectorMode;
 pub const SplitDirection = Binding.Action.SplitDirection;
 pub const SplitFocusDirection = Binding.Action.SplitFocusDirection;
+pub const SplitResizeDirection = Binding.Action.SplitResizeDirection;
 
 // Keymap is only available on macOS right now. We could implement it
 // in theory for XKB too on Linux but we don't need it right now.

src/input/Binding.zig

@@ -179,6 +179,10 @@ pub const Action = union(enum) {
     /// zoom/unzoom the current split.
     toggle_split_zoom: void,
 
+    /// Resize the current split by moving the split divider in the given
+    /// direction
+    resize_split: SplitResizeParameter,
+
     /// Show, hide, or toggle the terminal inspector for the currently
     /// focused terminal.
     inspector: InspectorMode,
@@ -227,6 +231,19 @@ pub const Action = union(enum) {
         right,
     };
 
+    // Extern because it is used in the embedded runtime ABI.
+    pub const SplitResizeDirection = enum(c_int) {
+        up,
+        down,
+        left,
+        right,
+    };
+
+    pub const SplitResizeParameter = struct {
+        SplitResizeDirection,
+        u16,
+    };
+
     // Extern because it is used in the embedded runtime ABI.
     pub const InspectorMode = enum(c_int) {
         toggle,