nsAutoRollup.h - mozsearch

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef nsAutoRollup_h__

#define nsAutoRollup_h__

#include "mozilla/Attributes.h"  // for MOZ_RAII

#include "mozilla/StaticPtr.h"   // for StaticRefPtr

#include "nsIContent.h"

namespace mozilla {

namespace widget {

// A situation can occur when a mouse event occurs over a menu label while the

// menu popup is already open. The expected behaviour is to close the popup.

// This happens by calling nsIRollupListener::Rollup before the mouse event is

// processed. However, in cases where the mouse event is not consumed, this

// event will then get targeted at the menu label causing the menu to open

// again. To prevent this, we store in sLastRollup a reference to the popup

// that was closed during the Rollup call, and prevent this popup from

// reopening while processing the mouse event.

// sLastRollup can only be set while an nsAutoRollup is in scope;

// when it goes out of scope sLastRollup is cleared automatically.

// As sLastRollup is static, it can be retrieved by calling

// nsAutoRollup::GetLastRollup.

class MOZ_RAII nsAutoRollup {

 public:

  nsAutoRollup();

  ~nsAutoRollup();

  // Convenience constructor that creates a nsAutoRollup and also sets

  // the last rollup.

  explicit nsAutoRollup(nsIContent* aRollup);

  static void SetLastRollup(nsIContent* aLastRollup);

  // Return the popup that was last rolled up, or null if there isn't one.

  static nsIContent* GetLastRollup();

 private:

  // Whether sLastRollup was clear when this nsAutoRollup

  // was created.

  bool mWasClear;

  // The number of nsAutoRollup instances active.

  static uint32_t sCount;

  // The last rolled up popup.

  static StaticRefPtr<nsIContent> sLastRollup;

};

}  // namespace widget

}  // namespace mozilla

#endif  // nsAutoRollup_h__