/*=========================================================================

   Program: ParaView
   Module:    $RCSfile$

   Copyright (c) 2005,2006 Sandia Corporation, Kitware Inc.
   All rights reserved.

   ParaView is a free software; you can redistribute it and/or modify it
   under the terms of the ParaView license version 1.2.

   See License_v1.2.txt for the full ParaView license.
   A copy of this license can be obtained by contacting
   Kitware Inc.
   28 Corporate Drive
   Clifton Park, NY 12065
   USA

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

========================================================================*/
#ifndef pqPropertyWidgetDecorator_h
#define pqPropertyWidgetDecorator_h

#include "pqPropertyWidget.h"
#include "vtkSmartPointer.h" // needed for vtkSmartPointer

class vtkPVXMLElement;

/// pqPropertyWidgetDecorator provides a mechanism to decorate pqPropertyWidget
/// instances to add logic to the widget to add additional control logic.
/// Subclasses can be used to logic to control when the widget is
/// enabled/disabled, hidden/visible, etc. based on values of other properties
/// of UI elements.
class PQCOMPONENTS_EXPORT pqPropertyWidgetDecorator : public QObject
{
  Q_OBJECT
  typedef QObject Superclass;
public:
  /// Constructor. \c parent cannot be NULL.
  /// \c xml is the XML element from the <Hints/> section for the proxy/property that
  /// resulted in the creation of the decorator. Decorators can be provided
  /// configuration parameters from the XML.
  pqPropertyWidgetDecorator(vtkPVXMLElement* xml, pqPropertyWidget* parent);
  virtual ~pqPropertyWidgetDecorator();

  /// Returns the pqPropertyWidget parent.
  pqPropertyWidget* parentWidget() const;

  /// Override this method to override the visibility of the widget in the
  /// panel. This is called after the generic tests for advanced and text
  /// filtering are passed. Since there can be multiple decorators, the first
  /// decorator that returns 'false' wins. Default implementation returns true.
  /// Thus subclasses typically override this method only to force the widget
  /// invisible given the current state.
  virtual bool canShowWidget(bool show_advanced) const
    {
    Q_UNUSED(show_advanced);
    return true;
    }

  /// Override this method to override the enable state of the widget in the
  /// panel. This is called after the generic tests for advanced and text
  /// filtering are passed. Since there can be multiple decorators, the first
  /// decorator that returns 'false' wins. Default implementation returns true.
  /// Thus subclasses typically override this method only to force the widget
  /// disabled given the current state.
  virtual bool enableWidget() const
    {
    return true;
    }

signals:
  /// This signal is fired whenever the decorator has determined that the panel
  /// *may* need a refresh since the state of the system has changed which would
  /// deem changes in the widget visibility or enable state.
  void visibilityChanged();
  void enableStateChanged();

protected:
  vtkPVXMLElement* xml() const;

private:
  Q_DISABLE_COPY(pqPropertyWidgetDecorator)
 
  vtkSmartPointer<vtkPVXMLElement> XML;
};

#endif
