Changed the logic of app.quit accelerator, introduced a dialog in it.

Also made functions such is_save_senstive() and save_overwrite()
publicly accessible for logic building.

Part-of: <https://gitlab.gnome.org/GNOME/loupe/-/merge_requests/576>

src/application.rs

@@ -169,7 +169,8 @@ impl LpApplication {
                                                 app_clone.quit();
                                             }
                                             "save" => {
-                                                edit_window_clone.save_as();
+                                                edit_window_clone
+                                                    .save_as_and_quit(app_clone.clone());
                                             }
                                             _ => {}
                                         }

src/widgets/edit_window.rs

@@ -25,6 +25,7 @@ use glycin::Operations;
 
 use super::LpImage;
 use super::edit::LpEditCrop;
+use crate::LpApplication;
 use crate::deps::*;
 use crate::util::ErrorType;
 use crate::util::gettext::*;
@@ -489,12 +490,15 @@ impl LpEditWindow {
         self.imp().is_save_sensitive()
     }
 
-    pub fn save_as(&self) {
+    pub fn save_as_and_quit(&self, app: LpApplication) {
         glib::spawn_future_local(glib::clone!(
             #[weak(rename_to=win)]
             self,
+            #[strong]
+            app,
             async move {
                 win.imp().save_overwrite().await;
+                app.quit()
             }
         ));
     }

src/widgets/window.rs

@@ -168,6 +168,13 @@ impl LpWindow {
         self.set_fullscreened(fullscreen);
     }
 
+    pub fn edit_window(&self) -> Option<LpEditWindow> {
+        self.imp()
+            .edit_window_child
+            .child()
+            .and_then(|w| w.downcast::<LpEditWindow>().ok())
+    }
+
     pub fn resize_default(&self) {
         let imp = self.imp();
 
@@ -268,13 +275,6 @@ impl LpWindow {
         }
     }
 
-    pub fn edit_window(&self) -> Option<LpEditWindow> {
-        self.imp()
-            .edit_window_child
-            .child()
-            .and_then(|w| w.downcast::<LpEditWindow>().ok())
-    }
-
     pub fn image_view(&self) -> LpImageView {
         self.imp().image_window.image_view()
     }