prototype DnD that works with plank dock

examples/app_library/grid_item/mod.rs

@@ -1,5 +1,11 @@
 use crate::app_group::AppGroup;
+use gdk4::ContentProvider;
+use gdk4::Display;
+use gio::File;
 use gtk4 as gtk;
+use gtk4::traits::WidgetExt;
+use gtk4::DragSource;
+use gtk4::IconTheme;
 mod imp;
 
 use gtk::prelude::*;
@@ -26,8 +32,35 @@ impl GridItem {
     pub fn set_app_info(&self, app_info: &gio::DesktopAppInfo) {
         let self_ = imp::GridItem::from_instance(self);
         self_.name.set_text(&app_info.name());
+
+        let drag = DragSource::builder()
+            .name("application library drag source")
+            .actions(gdk4::DragAction::COPY)
+            // .content()
+            .build();
+        self.add_controller(&drag);
+        if let Some(file) = app_info.filename() {
+            let file = File::for_path(file);
+            let provider = ContentProvider::for_value(&file.to_value());
+            drag.set_content(Some(&provider));
+        }
         if let Some(icon) = app_info.icon() {
             self_.image.set_from_gicon(&icon);
+            // set drag source icon if possible...
+            // gio Icon is not easily converted to a Paintable, but this seems to be the correct method
+            if let Some(default_display) = &Display::default() {
+                if let Some(icon_theme) = IconTheme::for_display(default_display) {
+                    if let Some(paintable_icon) = icon_theme.lookup_by_gicon(
+                        &icon,
+                        64,
+                        1,
+                        gtk4::TextDirection::None,
+                        gtk4::IconLookupFlags::empty(),
+                    ) {
+                        drag.set_icon(Some(&paintable_icon), 0, 0);
+                    }
+                }
+            }
         }
     }
 

examples/app_library/main.rs

@@ -13,12 +13,15 @@ use window::Window;
 
 fn main() {
     let app = gtk::Application::new(Some("com.cosmic.app_library"), Default::default());
-    app.connect_startup(|_app| load_css());
-
-    app.connect_activate(|app| {
-        build_ui(app);
+    app.connect_startup(|app| {
+        load_css();
+        build_ui(&app);
     });
 
+    // app.connect_activate(|app| {
+    //     build_ui(app);
+    // });
+
     app.run();
 }
 

examples/app_library/style.css

@@ -1,15 +1 @@
-description {
-    line-height: 1.5em;
-    background-image: none;
-    background-color: red;
-}
 
-row.row1 {
-    background-image: none;
-    background-color: black;
-}
-
-shortcut {
-    background-image: none;
-    background-color: green;
-}

examples/app_library/window/window.ui

@@ -50,7 +50,6 @@
             <property name="propagate-natural-height">true</property>
             <property name="min-content-height">150</property>
             <property name="max-content-height">300</property>
-            <property name="margin-top">12</property>
             <child>
               <object class="GtkGridView" id="group_grid_view">
                 <property name="min-columns">8</property>