window: implement window movement by dragging on Wayland

wezterm-gui/src/termwindow/mouseevent.rs

@@ -321,6 +321,7 @@ impl super::TermWindow {
                 TabBarItem::None => {
                     // Potentially starting a drag by the tab bar
                     self.window_drag_position.replace(event.clone());
+                    context.request_drag_move();
                 }
             },
             WMEK::Press(MousePress::Middle) => match self.tab_bar.hit_test(x) {

window/src/lib.rs

@@ -220,9 +220,18 @@ pub trait WindowOps {
     /// Resize the inner or client area of the window
     fn set_inner_size(&self, width: usize, height: usize);
 
+    /// Requests the windowing system to start a window drag.
+    ///
+    /// This is only implemented on backends that handle
+    /// window movement on the server side (Wayland).
+    fn request_drag_move(&self) {}
+
     /// Changes the location of the window on the screen.
     /// The coordinates are of the top left pixel of the
     /// client area.
+    ///
+    /// This is only implemented on backends that allow
+    /// windows to move themselves (not Wayland).
     fn set_window_position(&self, _coords: ScreenPoint) {}
 
     /// inform the windowing system of the current textual

window/src/os/wayland/copy_and_paste.rs

@@ -10,7 +10,7 @@ use wayland_client::Attached;
 #[derive(Default)]
 pub struct CopyAndPaste {
     data_offer: Option<WlDataOffer>,
-    last_serial: u32,
+    pub(crate) last_serial: u32,
 }
 
 impl std::fmt::Debug for CopyAndPaste {

window/src/os/wayland/pointer.rs

@@ -94,6 +94,7 @@ pub struct PointerDispatcher {
     auto_pointer: ThemedPointer,
     #[allow(dead_code)]
     themer: ThemeManager,
+    pub(crate) seat: WlSeat,
 }
 
 #[derive(Clone, Debug)]
@@ -237,6 +238,7 @@ impl PointerDispatcher {
             data_device,
             themer,
             auto_pointer,
+            seat: seat.clone(),
         })
     }
 

window/src/os/wayland/window.rs

@@ -793,9 +793,9 @@ impl WindowOps for WaylandWindow {
         });
     }
 
-    fn set_window_position(&self, coords: ScreenPoint) {
+    fn request_drag_move(&self) {
         WaylandConnection::with_window_inner(self.0, move |inner| {
-            inner.set_window_position(coords);
+            inner.request_drag_move();
             Ok(())
         });
     }
@@ -1000,7 +1000,13 @@ impl WaylandWindowInner {
         }
     }
 
-    fn set_window_position(&self, _coords: ScreenPoint) {}
+    fn request_drag_move(&self) {
+        if let Some(window) = self.window.as_ref() {
+            let serial = self.copy_and_paste.lock().unwrap().last_serial;
+            let conn = Connection::get().unwrap().wayland();
+            window.start_interactive_move(&conn.pointer.seat, serial);
+        }
+    }
 
     /// Change the title for the window manager
     fn set_title(&mut self, title: &str) {

window/src/os/x_and_wayland.rs

@@ -285,6 +285,14 @@ impl WindowOps for Window {
         }
     }
 
+    fn request_drag_move(&self) {
+        match self {
+            Self::X11(x) => x.request_drag_move(),
+            #[cfg(feature = "wayland")]
+            Self::Wayland(w) => w.request_drag_move(),
+        }
+    }
+
     fn set_window_position(&self, coords: ScreenPoint) {
         match self {
             Self::X11(x) => x.set_window_position(coords),