From 781f8c4661092b97b51f96fe664d7bd34af6ea3c Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <m@mitchellh.com>
Date: Fri, 28 Nov 2025 14:58:58 -0800
Subject: [PATCH] apprt/embedded: expose C APIs for layouts

---
 include/ghostty.h             | 30 +++++++++++++++++++++++++++---
 src/apprt/embedded.zig        | 14 ++++++++++++++
 src/apprt/layout.zig          |  2 +-
 src/datastruct/split_tree.zig |  2 +-
 4 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/include/ghostty.h b/include/ghostty.h
index 1d3db534f..77f7decff 100644
--- a/include/ghostty.h
+++ b/include/ghostty.h
@@ -30,8 +30,19 @@ typedef void* ghostty_app_t;
 typedef void* ghostty_config_t;
 typedef void* ghostty_surface_t;
 typedef void* ghostty_inspector_t;
-typedef void* ghostty_layout_window_t;
-typedef void* ghostty_layout_tab_t;
+
+// Layout API
+typedef void* ghostty_window_layout_t;
+typedef void* ghostty_tab_layout_t;
+typedef void* ghostty_tab_layout_leaf_t;
+typedef uint16_t ghostty_tab_layout_node_t;
+
+typedef struct {
+  bool horizontal;
+  float ratio;
+  ghostty_tab_layout_node_t left;
+  ghostty_tab_layout_node_t right;
+} ghostty_tab_layout_split_s;
 
 // All the types below are fully defined and must be kept in sync with
 // their Zig counterparts. Any changes to these types MUST have an associated
@@ -837,7 +848,7 @@ typedef enum {
 
 typedef union {
   ghostty_action_split_direction_e new_split;
-  ghostty_layout_window_t new_window_layout;
+  ghostty_window_layout_t new_window_layout;
   ghostty_action_fullscreen_e toggle_fullscreen;
   ghostty_action_move_tab_s move_tab;
   ghostty_action_goto_tab_e goto_tab;
@@ -1070,6 +1081,19 @@ void ghostty_inspector_metal_render(ghostty_inspector_t, void*, void*);
 bool ghostty_inspector_metal_shutdown(ghostty_inspector_t);
 #endif
 
+// Layout API
+size_t ghostty_window_layout_get_tabs_len(ghostty_window_layout_t);
+const ghostty_tab_layout_t* ghostty_window_layout_get_tabs(ghostty_window_layout_t);
+bool ghostty_tab_layout_is_empty(ghostty_tab_layout_t);
+size_t ghostty_tab_layout_get_nodes_len(ghostty_tab_layout_t);
+bool ghostty_tab_layout_is_split_node(ghostty_tab_layout_t, ghostty_tab_layout_node_t);
+ghostty_tab_layout_split_s ghostty_tab_layout_get_split_node(ghostty_tab_layout_t,
+                                                              ghostty_tab_layout_node_t);
+ghostty_tab_layout_leaf_t ghostty_tab_layout_get_leaf_node(ghostty_tab_layout_t,
+                                                            ghostty_tab_layout_node_t);
+uint64_t ghostty_tab_layout_leaf_get_id(ghostty_tab_layout_leaf_t);
+ghostty_config_t ghostty_tab_layout_leaf_get_config(ghostty_tab_layout_leaf_t);
+
 // APIs I'd like to get rid of eventually but are still needed for now.
 // Don't use these unless you know what you're doing.
 void ghostty_set_window_background_blur(ghostty_app_t, void*);
diff --git a/src/apprt/embedded.zig b/src/apprt/embedded.zig
index da7a585a5..948a2574d 100644
--- a/src/apprt/embedded.zig
+++ b/src/apprt/embedded.zig
@@ -20,6 +20,7 @@ const CoreInspector = @import("../inspector/main.zig").Inspector;
 const CoreSurface = @import("../Surface.zig");
 const configpkg = @import("../config.zig");
 const Config = configpkg.Config;
+const layout = @import("layout.zig");
 
 const log = std.log.scoped(.embedded_window);
 
@@ -1340,6 +1341,19 @@ pub const CAPI = struct {
         }
     }
 
+    // Layout C API exports
+    comptime {
+        @export(&layout.Window.CApi.get_tabs_len, .{ .name = "ghostty_window_layout_get_tabs_len" });
+        @export(&layout.Window.CApi.get_tabs, .{ .name = "ghostty_window_layout_get_tabs" });
+        @export(&layout.SplitTree.CApi.is_empty, .{ .name = "ghostty_tab_layout_is_empty" });
+        @export(&layout.SplitTree.CApi.len, .{ .name = "ghostty_tab_layout_get_nodes_len" });
+        @export(&layout.SplitTree.CApi.is_split, .{ .name = "ghostty_tab_layout_is_split_node" });
+        @export(&layout.SplitTree.CApi.get_split, .{ .name = "ghostty_tab_layout_get_split_node" });
+        @export(&layout.SplitTree.CApi.get_leaf, .{ .name = "ghostty_tab_layout_get_leaf_node" });
+        @export(&layout.SplitTree.View.CApi.get_id, .{ .name = "ghostty_tab_layout_leaf_get_id" });
+        @export(&layout.SplitTree.View.CApi.get_config, .{ .name = "ghostty_tab_layout_leaf_get_config" });
+    }
+
     /// Create a new app.
     export fn ghostty_app_new(
         opts: *const apprt.runtime.App.Options,
diff --git a/src/apprt/layout.zig b/src/apprt/layout.zig
index 32c1aa145..09a4688d2 100644
--- a/src/apprt/layout.zig
+++ b/src/apprt/layout.zig
@@ -17,7 +17,7 @@ pub const Window = struct {
         }
 
         pub fn get_tabs(self: *const Window) callconv(.c) [*]const SplitTree {
-            return &self.tabs;
+            return self.tabs.ptr;
         }
     };
 };
diff --git a/src/datastruct/split_tree.zig b/src/datastruct/split_tree.zig
index 78a8b691c..a6f8a9511 100644
--- a/src/datastruct/split_tree.zig
+++ b/src/datastruct/split_tree.zig
@@ -1351,7 +1351,7 @@ pub fn SplitTree(comptime V: type) type {
                 };
             }
 
-            pub fn get_leaf(self: *const Self, handle: Node.Handle) *View {
+            pub fn get_leaf(self: *const Self, handle: Node.Handle) callconv(.c) *View {
                 return self.nodes[handle.idx()].leaf;
             }
         };