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

services/ui/ws/drag_controller.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SERVICES_UI_WS_DRAG_CONTROLLER_H_
 #define SERVICES_UI_WS_DRAG_CONTROLLER_H_
 
 #include "base/memory/weak_ptr.h"
 #include "services/ui/common/types.h"
 #include "services/ui/ws/ids.h"
 #include "services/ui/ws/server_window_observer.h"
 
 namespace ui {
 namespace ws {
 
 namespace test {
 class DragControllerTestApi;
 }
 
+class DragCursorUpdater;
 class DragSource;
 class DragTargetConnection;
 
 // Represents all the data around the current ongoing drag operation.
 //
 // There should only be one instance of this class per userid. The
 // 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,
                  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data,
                  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();
 
   // Responds to a pointer move/release event. Returns true if the event was
   // handled by the drag.
   bool DispatchPointerEvent(const ui::PointerEvent& event,
                             ServerWindow* current_target);
 
   void OnWillDestroyDragTargetConnection(DragTargetConnection* connection);
 
@@ skipping 10 matching lines @@
   // Returns the number of events on |window|. A value of 1 means that there's
   // a single event outstanding that we're waiting for a response from the
   // client, all values over 1 are queued and will be dispatched when the event
   // in the front of the queue gets a response.
   size_t GetSizeOfQueueForWindow(ServerWindow* window);
 
   // Sets |current_target_window_| to |current_target|, making sure that we add
   // 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);
 
   void QueueOperation(ServerWindow* window,
                       OperationType type,
                       uint32_t event_flags,
                       gfx::Point screen_position);
   void DispatchOperation(ServerWindow* window, WindowState* state);
   void OnRespondToOperation(ServerWindow* window);
 
   // Callback methods.
   void OnDragStatusCompleted(const WindowId& id, uint32_t bitmask);
   void OnDragDropCompleted(const WindowId& id, uint32_t action);
 
   // ServerWindowObserver:
   void OnWindowDestroying(ServerWindow* window) override;
 
   // 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;
 
   ServerWindow* source_window_;
   ServerWindow* current_target_window_ = nullptr;
 
   // The target connection that |source_window_| is part of.
   DragTargetConnection* source_connection_;
 
@@ skipping 12 matching lines @@
 
   base::WeakPtrFactory<DragController> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DragController);
 };
 
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_DRAG_CONTROLLER_H_