window: Limit HeaderBar to min width as nat width

Before we were doing the same with just the title in the HeaderBar. This
gave problems with correctly measuring for ADW_CENTERING_POLICY_LOOSE.

src/widgets/shy_bin.rs

@@ -0,0 +1,79 @@
+// Copyright (c) 2023 Sophie Herold
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+//! A bin that only has min width as natural width
+//!
+//! This bin does not claim its complete width as natural width. The HeaderBar
+//! is wrapped in with this widget. This prevents the window from growing based
+//! on a long file name in the title instead of just fitting to the image
+//! size.
+
+use adw::prelude::*;
+use adw::subclass::prelude::*;
+
+use crate::deps::*;
+
+mod imp {
+    use super::*;
+
+    #[derive(Debug, Default)]
+    pub struct LpShyBin {}
+
+    #[glib::object_subclass]
+    impl ObjectSubclass for LpShyBin {
+        const NAME: &'static str = "LpShyBin";
+        type Type = super::LpShyBin;
+        type ParentType = adw::Bin;
+    }
+
+    impl ObjectImpl for LpShyBin {
+        fn constructed(&self) {
+            self.parent_constructed();
+            let obj = self.obj();
+
+            obj.set_layout_manager(None::<gtk::LayoutManager>);
+            obj.set_hexpand(true);
+        }
+    }
+
+    impl WidgetImpl for LpShyBin {
+        fn measure(&self, orientation: gtk::Orientation, for_size: i32) -> (i32, i32, i32, i32) {
+            let mut measure = self.obj().child().unwrap().measure(orientation, for_size);
+
+            if orientation == gtk::Orientation::Horizontal {
+                // Set natural size to minimal size
+                measure.1 = measure.0;
+            }
+
+            measure
+        }
+
+        fn size_allocate(&self, width: i32, height: i32, baseline: i32) {
+            self.obj()
+                .child()
+                .unwrap()
+                .allocate(width, height, baseline, None);
+        }
+    }
+
+    impl BinImpl for LpShyBin {}
+}
+
+glib::wrapper! {
+    pub struct LpShyBin(ObjectSubclass<imp::LpShyBin>)
+        @extends gtk::Widget, adw::Bin;
+}