mus: Keep track of the drag cursor during DnD operations.

services/ui/ws/drag_controller.h

Index: services/ui/ws/drag_controller.h
diff --git a/services/ui/ws/drag_controller.h b/services/ui/ws/drag_controller.h
index 3b781a44a2ebb43d2732ace7123f3f62b912b5e7..da28a591b177df6eee8acad9754b5227f0377333 100644
--- a/services/ui/ws/drag_controller.h
+++ b/services/ui/ws/drag_controller.h
@@ -17,6 +17,7 @@ namespace test {
 class DragControllerTestApi;
 }
 
+class DragCursorUpdater;
 class DragSource;
 class DragTargetConnection;
 
@@ -26,7 +27,8 @@ class DragTargetConnection;
 // WindowManagerState's EventDispatcher creates and owns this instance.
 class DragController : public ServerWindowObserver {
  public:
-  DragController(DragSource* source,
+  DragController(DragCursorUpdater* cursor_updater,
+                 DragSource* source,
                  ServerWindow* source_window,
                  DragTargetConnection* source_connection,
                  int32_t drag_pointer,
@@ -34,6 +36,8 @@ class DragController : public ServerWindowObserver {
                  uint32_t drag_operations);
   ~DragController() override;
 
+  int32_t current_cursor() { return current_cursor_; }

[sky, 2016/09/28 15:38:13]

const

+
   // Cancels the current drag, ie, due to the user pressing Escape.
   void Cancel();
 
@@ -64,6 +68,14 @@ class DragController : public ServerWindowObserver {
   // and release ServerWindow observers correctly.
   void SetCurrentTargetWindow(ServerWindow* current_target);
 
+  // Updates the possible cursor effects for |window|. |effect_bitmask| is a
+  // bitmask of the current valid drag operations.
+  void UpdateCursor(ServerWindow* window, uint32_t effect_bitmask);

[sky, 2016/09/28 15:38:13]

This seems more like SetWindowDropOperations. It may end up updating the cursor
too, but it seems more related to setting the drop operations.

[Elliot Glaysher, 2016/09/28 18:15:31]

Done.

+
+  // Returns the ui::mojom::Cursor for the window reporting it can handle
+  // |window_operations|.
+  int32_t CursorForWindowOperations(uint32_t window_operations);

[sky, 2016/09/28 15:38:13]

Is there a reason you prefer using int32_t as the type for these rather than
ui::mojom::Cursor?

[Elliot Glaysher, 2016/09/28 18:15:31]

Because the consumer uses int32_t. I can, in a separate patch, go through window
server and replace int32_t with ui::mojom::Cursors (and remove the
static_cast<>s which have become a pattern) if you like.

+
   // Ensure that |window| has an entry in |window_state_| and that we're an
   // observer.
   void EnsureWindowObserved(ServerWindow* window);
@@ -85,12 +97,18 @@ class DragController : public ServerWindowObserver {
   // Our owner.
   DragSource* source_;
 
+  // Object to notify about all cursor changes.
+  DragCursorUpdater* cursor_updater_;
+
   // A bit-field of acceptable drag operations offered by the source.
   const uint32_t drag_operations_;
 
   // Only act on pointer events that meet this id.
   const int32_t drag_pointer_id_;
 
+  // The current mouse cursor during the drag.
+  int32_t current_cursor_;
+
   // Sending OnDragOver() to our |source_| destroys us; there is a period where
   // we have to continue to exist, but not process any more pointer events.
   bool waiting_for_final_drop_response_ = false;