SelfContainedViewListener.h

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/*
 * Copyright (c) 2019 pongasoft
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 *
 * @author Yan Pujante
 */
#pragma once

#include <vstgui4/vstgui/lib/iviewlistener.h>
#include <vstgui4/vstgui/lib/cview.h>
#include <pongasoft/logging/logging.h>

namespace pongasoft::VST::GUI::Views {

using namespace VSTGUI;

class SelfContainedViewListener : protected IViewListenerAdapter, public std::enable_shared_from_this<SelfContainedViewListener>
{
public:
  template<typename T, typename ...Args>
  static std::shared_ptr<T> create(CView *iView, Args&& ...iArgs)
  {
    // ensures that TView is a subclass of CView
    static_assert(std::is_convertible<T *, SelfContainedViewListener*>::value, "T must be a subclass of SelfContainedViewListener");

    auto res = std::make_shared<T>(std::forward<Args>(iArgs)...);
    res->registerView(iView);
    return res;
  }

  virtual void unregister()
  {
    if(fView)
    {
      fView->unregisterViewListener(this);
      fView = nullptr;
      fThis = nullptr;
    }
  }

  SelfContainedViewListener() = default;

  virtual std::shared_ptr<SelfContainedViewListener> registerView(CView *iView)
  {
    DCHECK_F(iView != nullptr);

    // first we close any prior connection if there was one
    unregister();

    fView = iView;
    fView->registerViewListener(this);
    fThis = shared_from_this();

    return fThis;
  }

protected:

  void viewWillDelete(CView *iView) override
  {
    DCHECK_F(iView == fView);

    unregister();
  }

protected:
  std::shared_ptr<SelfContainedViewListener> fThis{};
  CView *fView{};
};

}