Adds support for autoscrolling on drag to bookmark tree/table....

chrome/browser/bookmarks/bookmark_drop_info.h

+// Copyright (c) 2006-2008 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 CHROME_BROWSER_BOOKMARKS_BOOKMARK_DROP_INFO_H_
+#define CHROME_BROWSER_BOOKMARKS_BOOKMARK_DROP_INFO_H_
+
+#include <windows.h>
+
+#include "base/timer.h"
+#include "chrome/browser/bookmarks/bookmark_drag_data.h"
+
+namespace views {
+class DropTargetEvent;
+}
+
+// BookmarkDropInfo is a pure virtual class that provides auto-scrolling
+// behavior and a handful of fields used for managing a bookmark drop.
+// BookmarkDropInfo is used by both BookmarkTableView and
+// BookmarksFolderTreeView.
+class BookmarkDropInfo {
+ public:
+  BookmarkDropInfo(HWND hwnd, int top_margin);
+  virtual ~BookmarkDropInfo() {}
+
+  // Invoke this from OnDragUpdated. It resets source_operations,
+  // is_control_down, last_y and updates the autoscroll timer as necessary.
+  void Update(const views::DropTargetEvent& event);
+
+  // Data from the drag.
+  void SetData(const BookmarkDragData& data) { data_ = data; }
+  BookmarkDragData& data() { return data_; }
+
+  // Value of event.GetSourceOperations when Update was last invoked.
+  int source_operations() const { return source_operations_; }
+
+  // Whether the control key was down last time Update was invoked.
+  bool is_control_down() const { return is_control_down_; }
+
+  // Y position of the event last passed to Update.
+  int last_y() { return last_y_; }
+
+  // The drop operation that should occur. This is not updated by
+  // BookmarkDropInfo, but provided for subclasses.
+  void set_drop_operation(int drop_operation) {
+    drop_operation_ = drop_operation;
+  }
+  int drop_operation() const { return drop_operation_; }
+
+ protected:
+  // Invoked if we autoscroll. When invoked subclasses need to determine
+  // whether the drop is valid again as what is under the mouse has likely
+  // scrolled.
+  virtual void Scrolled() = 0;
+
+ private:
+  // Invoked from the timer. Scrolls up/down a line.
+  void Scroll();
+
+  BookmarkDragData data_;
+
+  int source_operations_;
+
+  bool is_control_down_;
+
+  int last_y_;
+
+  int drop_operation_;
+
+  HWND hwnd_;
+
+  // Margin in addition to views::kAutoscrollSize that the mouse is allowed to
+  // be over before we autoscroll.
+  int top_margin_;
+
+  // When autoscrolling this determines if we're scrolling up or down.
+  bool scroll_up_;
+
+  // Used when autoscrolling.
+  base::RepeatingTimer<BookmarkDropInfo> scroll_timer_;
+  
+  DISALLOW_COPY_AND_ASSIGN(BookmarkDropInfo);
+};
+
+#endif  // CHROME_BROWSER_BOOKMARKS_BOOKMARK_DROP_INFO_H_