Stub DndProvider for dummy platform

src/platform/dummy.rs

@@ -1,6 +1,9 @@
-use crate::ClipboardProvider;
+use crate::{dnd::DndProvider, ClipboardProvider};
 
+use dnd::{DndAction, DndDestinationRectangle, DndSurface, Icon};
+use mime::{AllowedMimeTypes, AsMimeTypes};
 use raw_window_handle::HasDisplayHandle;
+use std::borrow::Cow;
 
 pub struct Clipboard;
 
@@ -23,6 +26,45 @@ impl ClipboardProvider for Clipboard {
     }
 }
 
+impl DndProvider for Clipboard {
+    fn init_dnd(
+        &self,
+        _tx: Box<dyn dnd::Sender<DndSurface> + Send + Sync + 'static>,
+    ) {
+    }
+
+    fn start_dnd<D: AsMimeTypes + Send + 'static>(
+        &self,
+        _internal: bool,
+        _source_surface: DndSurface,
+        _icon_surface: Option<Icon>,
+        _content: D,
+        _actions: DndAction,
+    ) {
+    }
+
+    fn end_dnd(&self) {}
+
+    fn register_dnd_destination(
+        &self,
+        _surface: DndSurface,
+        _rectangles: Vec<DndDestinationRectangle>,
+    ) {
+    }
+
+    fn set_action(&self, _action: DndAction) {}
+
+    fn peek_offer<D: AllowedMimeTypes + 'static>(
+        &self,
+        _mime_type: Option<Cow<'static, str>>,
+    ) -> std::io::Result<D> {
+        Err(std::io::Error::new(
+            std::io::ErrorKind::Other,
+            "DnD not supported",
+        ))
+    }
+}
+
 #[derive(Debug, Clone, Copy, thiserror::Error)]
 enum Error {
     #[error("unimplemented")]