MacViews: Implemented Drag & Drop

ui/views/cocoa/drag_drop_client_mac.h

Index: ui/views/cocoa/drag_drop_client_mac.h
diff --git a/ui/views/cocoa/drag_drop_client_mac.h b/ui/views/cocoa/drag_drop_client_mac.h
new file mode 100644
index 0000000000000000000000000000000000000000..f9330bf9eaeabf6d0279b9357ae21ec0c9450612
--- /dev/null
+++ b/ui/views/cocoa/drag_drop_client_mac.h
@@ -0,0 +1,97 @@
+// 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 UI_VIEWS_COCOA_DRAG_DROP_CLIENT_MAC_H_
+#define UI_VIEWS_COCOA_DRAG_DROP_CLIENT_MAC_H_
+
+#import <Cocoa/Cocoa.h>
+
+#import "base/mac/scoped_nsobject.h"
+#include "base/macros.h"
+#include "base/run_loop.h"
+#include "ui/base/dragdrop/drag_drop_types.h"
+#include "ui/views/views_export.h"
+#include "ui/views/widget/drop_helper.h"
+
+// This class acts as a bridge between NSPasteboardItem and OSExchangeData by
+// implementing NSPasteboardItemDataProvider and writing data from
+// OSExchangeData into the pasteboard.
+VIEWS_EXPORT
+@interface CocoaDragDropDataProvider : NSObject<NSPasteboardItemDataProvider>
+- (id)initWithData:(const ui::OSExchangeData&)data;
+@end
+
+namespace gfx {
+class Point;
+}
+
+namespace ui {
+class OSExchangeData;
+}
+
+namespace views {
+namespace test {
+class CocoaDragDropTest;
+}
+
+class BridgedNativeWidget;
+class DropHelper;
+
+// Implements drag and drop on MacViews. This class acts as a bridge between
+// the Views and native system's drag and drop. This class mimics
+// DesktopDragDropClientAuraX11.
+class VIEWS_EXPORT DragDropClientMac {
+ public:
+  explicit DragDropClientMac(BridgedNativeWidget* bridge, View* root_view);
+  ~DragDropClientMac();
+
+  // Initiates a drag and drop session. Returns the drag operation that was
+  // applied at the end of the drag drop session.
+  void StartDragAndDrop(View* view,
+                        const ui::OSExchangeData& data,
+                        int operation,
+                        ui::DragDropTypes::DragEventSource source);
+
+  // Called when mouse is dragged during a drag and drop.
+  NSDragOperation DragUpdate(id<NSDraggingInfo>);
+
+  // Called when mouse is released during a drag and drop.
+  NSDragOperation Drop(id<NSDraggingInfo> sender);
+
+  // Called when the drag and drop session has ended.
+  void EndDrag();
+
+  DropHelper* drop_helper() { return drop_helper_.get(); }
+
+ private:
+  friend class test::CocoaDragDropTest;
+
+  // Converts the given NSPoint to the coordinate system in Views.
+  gfx::Point LocationInView(NSPoint point) const;
+
+  // Provides the data for the drag and drop session.
+  base::scoped_nsobject<CocoaDragDropDataProvider> data_source_;
+
+  // Used to handle drag and drop with Views.
+  std::unique_ptr<DropHelper> drop_helper_;

[tapted, 2016/06/01 01:57:01]

Can this just be

DropHelper drop_helper_;

we can initialize it in the initializer list.

[spqchan, 2016/06/01 19:09:29]

I don't think it'll work, since DropHelper is DISALLOW_COPY_AND_ASSIGN, unless
I'm missing something here.

[tapted, 2016/06/02 00:24:50]

It should still work. DragDropClientMac is also DISALLOW_COPY_AND_ASSIGN so
there shouldn't be any code generated that tries to copy or assign its members.

And this is sorta called out in the chromium style guide, so we should probably
try to get it to work - i.e.
https://www.chromium.org/developers/coding-style#TOC-Forward-declarations-vs....
says "if it would otherwise make sense to use a type as a member by-value, don't
convert it to a pointer just to be able to forward-declare the type"

Generally, if there's a unique_ptr that's assigned in the constructor and then
never changes for the life of the object, then it should be a member by-value to
avoid the separate allocation

+
+  // The drag and drop operation.
+  int operation_;
+
+  // The bridge between the content view and the drag drop client.
+  BridgedNativeWidget* bridge_;  // Weak. Owns |this|.
+
+  // True if a runloop is running. This is reqired for tests, in which
+  // a runloop does not happen.
+  bool is_run_loop_running_;
+
+  // The closure for the drag and drop's runloop.
+  base::Closure quit_closure_;
+
+  DISALLOW_COPY_AND_ASSIGN(DragDropClientMac);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_COCOA_DRAG_DROP_CLIENT_MAC_H_