window: Remove default drop target style

The default does not fit well with our new custom one.

This also removes a bunch of code which was not used.

Part-of: <https://gitlab.gnome.org/GNOME/loupe/-/merge_requests/258>

data/gtk/window.ui

@@ -169,12 +169,9 @@
                 <property name="reveal-flap" bind-source="properties_button" bind-property="active" bind-flags="bidirectional|sync-create"/>
                 <property name="content">
                   <object class="LpDragOverlay" id="drag_overlay">
+                    <property name="drop_target">drop_target</property>
                     <property name="overlayed">
                       <object class="AdwBin">
-                        <property name="margin-top">24</property>
-                        <property name="margin-bottom">24</property>
-                        <property name="margin-start">24</property>
-                        <property name="margin-end">24</property>
                         <property name="can-target">false</property>
                         <style>
                           <class name="lp-dragging-area-highlight"/>
@@ -185,6 +182,9 @@
                       <object class="GtkStack" id="stack">
                         <property name="visible-child">status_page</property>
                         <property name="vexpand">True</property>
+                        <style>
+                          <class name="drop-widget" />
+                        </style>
                         <child>
                           <object class="GtkDropTarget" id="drop_target">
                             <property name="actions">copy</property>

data/resources/style.css

@@ -31,13 +31,17 @@ row.property label.subtitle {
   box-shadow: 0 0 10px rgba(0, 0, 0, 200);
 }
 
-.custom-drag-n-drop-highlight {
+/* Remove default adwaita style */
+.drop-widget:drop(active):focus,
+.drop-widget:drop(active) {
   box-shadow: none;
 }
 
+/* Drag overlay */
 .lp-dragging-area-highlight {
   border-radius: 8px;
   background-color: alpha(@blue_2, 0.35);
+  margin: 24px;
 }
 
 lpprintpreview {

src/widgets/drag_overlay.rs

@@ -16,10 +16,11 @@
 //
 // SPDX-License-Identifier: GPL-3.0-or-later
 
-use gtk::{glib, prelude::*};
+use crate::deps::*;
+use adw::prelude::*;
 
 mod imp {
-    use std::cell::RefCell;
+    use once_cell::sync::OnceCell;
 
     use adw::subclass::prelude::*;
     use glib::{ParamSpec, Properties, Value};
@@ -37,9 +38,8 @@ mod imp {
         pub overlayed: Option<gtk::Widget>,
         pub overlay: gtk::Overlay,
         pub revealer: gtk::Revealer,
-        #[property(set = Self::set_drop_target, get, explicit_notify)]
-        pub drop_target: RefCell<Option<gtk::DropTarget>>,
-        pub handler_id: RefCell<Option<glib::SignalHandlerId>>,
+        #[property(set = Self::set_drop_target, get, explicit_notify, construct_only)]
+        pub drop_target: OnceCell<gtk::DropTarget>,
     }
 
     #[glib::object_subclass]
@@ -47,6 +47,10 @@ mod imp {
         const NAME: &'static str = "LpDragOverlay";
         type Type = super::LpDragOverlay;
         type ParentType = adw::Bin;
+
+        fn class_init(klass: &mut Self::Class) {
+            klass.set_css_name("lpdragoverlay");
+        }
     }
 
     impl ObjectImpl for LpDragOverlay {
@@ -88,32 +92,20 @@ mod imp {
             self.revealer.set_child(overlayed.as_ref());
         }
 
-        pub fn set_drop_target(&self, drop_target: &gtk::DropTarget) {
-            if let Some(target) = self.drop_target.borrow_mut().take() {
-                self.obj().remove_controller(&target);
-
-                if let Some(handler_id) = self.handler_id.borrow_mut().take() {
-                    target.disconnect(handler_id);
-                }
-            }
-
-            let handler_id = drop_target.connect_current_drop_notify(
+        pub fn set_drop_target(&self, drop_target: gtk::DropTarget) {
+            drop_target.connect_current_drop_notify(
                 glib::clone!(@weak self.revealer as revealer => move |target| {
                     let reveal = target.current_drop().is_some();
                     revealer.set_reveal_child(reveal);
                 }),
             );
-            self.handler_id.replace(Some(handler_id));
 
-            // avoid `gtk_event_controller_get_widget (controller) == NULL` failing
-            if drop_target.widget().is_visible() {
-                self.obj().add_controller(drop_target.clone());
-                self.drop_target.replace(Some(drop_target.clone()));
+            self.drop_target.set(drop_target).unwrap();
+
             self.obj().notify("drop-target");
         }
     }
 }
-}
 
 glib::wrapper! {
     pub struct LpDragOverlay(ObjectSubclass<imp::LpDragOverlay>)

src/window.rs

@@ -419,7 +419,6 @@ mod imp {
                     true
                 }),
             );
-            self.drag_overlay.set_drop_target(&*self.drop_target);
         }
     }