ui/base/win/mouse_wheel_util.h

// Copyright (c) 2011 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_BASE_WIN_MOUSE_WHEEL_UTIL_H_
#define UI_BASE_WIN_MOUSE_WHEEL_UTIL_H_

#include <windows.h>

#include "ui/base/ui_base_export.h"

namespace ui {

class ViewProp;

// Marks the passed |hwnd| as supporting mouse-wheel message rerouting.
// We reroute the mouse wheel messages to such HWND when they are under the
// mouse pointer (but are not the active window). Callers own the returned
// object.
UI_BASE_EXPORT ViewProp* SetWindowSupportsRerouteMouseWheel(HWND hwnd);

// Forwards mouse wheel messages to the window under it.
// Windows sends mouse wheel messages to the currently active window.
// This causes a window to scroll even if it is not currently under the mouse
// wheel. The following code gives mouse wheel messages to the window under the
// mouse wheel in order to scroll that window. This is arguably a better user
// experience.  The returns value says whether the mouse wheel message was
// successfully redirected.
UI_BASE_EXPORT bool RerouteMouseWheel(HWND window,
                                      WPARAM w_param,
                                      LPARAM l_param);

}  // namespace ui

#endif  // UI_BASE_WIN_MOUSE_WHEEL_UTIL_H_