apprt/gtk-ng: helper for getAncestor

src/apprt/gtk-ng/class/application.zig

@@ -22,6 +22,7 @@ const xev = @import("../../../global.zig").xev;
 const CoreConfig = configpkg.Config;
 const CoreSurface = @import("../../../Surface.zig");
 
+const ext = @import("../ext.zig");
 const adw_version = @import("../adw_version.zig");
 const gtk_version = @import("../gtk_version.zig");
 const winprotopkg = @import("../winproto.zig");
@@ -1285,13 +1286,13 @@ const Action = struct {
                 // be aware they might be in windows but at the app level we
                 // can do this.
                 const surface = core.rt_surface.surface;
-                const window_widget = surface
-                    .as(gtk.Widget)
-                    .getAncestor(gobject.ext.typeFor(Window)) orelse {
+                const window = ext.getAncestor(
+                    Window,
+                    surface.as(gtk.Widget),
+                ) orelse {
                     log.warn("surface is not in a window, ignoring new_tab", .{});
                     return false;
                 };
-                const window = gobject.ext.cast(Window, window_widget).?;
                 window.newTab(core);
                 return true;
             },

src/apprt/gtk-ng/class/window.zig

@@ -11,6 +11,7 @@ const i18n = @import("../../../os/main.zig").i18n;
 const apprt = @import("../../../apprt.zig");
 const input = @import("../../../input.zig");
 const CoreSurface = @import("../../../Surface.zig");
+const ext = @import("../ext.zig");
 const gtk_version = @import("../gtk_version.zig");
 const adw_version = @import("../adw_version.zig");
 const gresource = @import("../build/gresource.zig");
@@ -719,17 +720,13 @@ pub const Window = extern struct {
         _: *CloseConfirmationDialog,
         page: *adw.TabPage,
     ) callconv(.c) void {
-        const tab_view_widget = page
-            .getChild()
-            .as(gtk.Widget)
-            .getAncestor(gobject.ext.typeFor(adw.TabView)) orelse {
+        const tab_view = ext.getAncestor(
+            adw.TabView,
+            page.getChild().as(gtk.Widget),
+        ) orelse {
             log.warn("close confirmation called for non-existent page", .{});
             return;
         };
-        const tab_view = gobject.ext.cast(
-            adw.TabView,
-            tab_view_widget,
-        ).?;
         tab_view.closePageFinish(page, @intFromBool(true));
     }
 
@@ -737,17 +734,13 @@ pub const Window = extern struct {
         _: *CloseConfirmationDialog,
         page: *adw.TabPage,
     ) callconv(.c) void {
-        const tab_view_widget = page
-            .getChild()
-            .as(gtk.Widget)
-            .getAncestor(gobject.ext.typeFor(adw.TabView)) orelse {
+        const tab_view = ext.getAncestor(
+            adw.TabView,
+            page.getChild().as(gtk.Widget),
+        ) orelse {
             log.warn("close confirmation called for non-existent page", .{});
             return;
         };
-        const tab_view = gobject.ext.cast(
-            adw.TabView,
-            tab_view_widget,
-        ).?;
         tab_view.closePageFinish(page, @intFromBool(false));
     }
 

src/apprt/gtk-ng/ext.zig

@@ -0,0 +1,19 @@
+//! Extensions/helpers for GTK objects, following a similar naming
+//! style to zig-gobject. These should, wherever possible, be Zig-friendly
+//! wrappers around existing GTK functionality, rather than complex new
+//! helpers.
+
+const std = @import("std");
+const assert = std.debug.assert;
+
+const gobject = @import("gobject");
+const gtk = @import("gtk");
+
+/// Wrapper around `gtk.Widget.getAncestor` to get the widget ancestor
+/// of the given type `T`, or null if it doesn't exist.
+pub fn getAncestor(comptime T: type, widget: *gtk.Widget) ?*T {
+    const ancestor_ = widget.getAncestor(gobject.ext.typeFor(T));
+    const ancestor = ancestor_ orelse return null;
+    // We can assert the unwrap because getAncestor above
+    return gobject.ext.cast(T, ancestor).?;
+}