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 /* This file is part of the TikZKit project.
  *
  * Copyright (C) 2015-2016 Dominik Haumann <dhaumann@kde.org>
  *
  * This library is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Library General Public License as published
  * by the Free Software Foundation, either version 2 of the License, or
  * (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, see
  * <http://www.gnu.org/licenses/>.
  */
 #ifndef TIKZ_CORE_ABSTRACT_PROPERTY_H
 #define TIKZ_CORE_ABSTRACT_PROPERTY_H
 
 #include "tikz_export.h"
 
 #include <QString>
 
 class QJsonObject;
 
 namespace tikz {
 namespace core {
 
 class PropertyPrivate;
 class Entity;
 class PropertyInterface;
 
 /**
  * Base class for properties.
  *
  * TODO / FIXME:
  * - merge PropertyInterface into Entity? --> then toJson/fromJson is much simpler
  * - add TikzFormatter classes: "property name=value", only "value",
  *   only "double" for double lines, ...
  *
  * @see Entity
  */
 class TIKZKITCORE_EXPORT Property
 {
 public:
     /**
      * Constructor that creates a property @p propertyName as part of @p entity.
      */
     explicit Property(const QString & propertyName, PropertyInterface * interface);
 
     /**
      * Destructor.
      */
     virtual ~Property();
 
     /**
      * Returns the PropertyInterface passed in the constructor.
      * This is typically an Entity this property belongs to.
      */
     PropertyInterface * propertyInterface() const;
 
     /**
      * Returns the property called @p propertyName() from the parent PropertyInterface.
      * This is equivalent to calling (with null pointer checks)
      * propertyInterface()->parentPropertyInterface()->property(propertyName()).
      * A null pointer is returned if no parent interface exists, or if the parent
      * interface does not contain a property called @p propertyName().
      */
     Property * parentProperty() const;
 
     /**
      * Helper function. Overload of parentProperty(), static_cast<>ing to T.
      */
     template<class T>
     T * parentProperty() const
     {
         return static_cast<T *>(parentProperty());
     }
 
     /**
      * Returns the associated Entity, or null, if no Entity was given.
      */
     Entity * entity() const;
 
     /**
      * Returns the property name of this Property.
      * The returned string is used as identifier to query for a certain property.
      */
     QString propertyName() const;
 
     /**
      * Set the user visible name of this Property to @p name.
      * This title is used as display string to the user, e.g. "Line Width"
      * or "Fill Color".
      */
     void setTitle(const QString & name);
 
     /**
      * Returns the user-visible name that was set with setTitle().
      */
     QString title() const;
 
     /**
      * Returns the type of the property.
      * The type is used to cast the property to the respective derived type.
      * Additionally, the type helps to serialize and deserialize the Property
      */
     virtual const char * propertyType() const = 0;
 
     /**
      * Reset the property to its default value.
      * @see isSet()
      */
     virtual void unset();
 
     /**
      * Returns @e true, if this property was set, otherwise false.
      */
     bool isSet() const;
 
 public: // load & save
     /**
      * Load the Property state from the @p json object.
      */
     void load(const QJsonObject & json);
 
     /**
      * Save the Property state to the @p json object.
      */
     void save(QJsonObject & json);
 
 protected:
     /**
      * Load the payload of the Property state from the @p json object.
      * The default implementation is empty.
      */
     virtual void loadData(const QJsonObject & json);
 
     /**
      * Save the payload of the Property state to the @p json object.
      * The default implementation is empty.
      */
     virtual void saveData(QJsonObject & json);
 
 public: // change management
     /**
      * Helper class for signaling changes.
      *
      * When creating a Transaction instance, the constructor will automatically
      * call the PropertyInterface::notifyAboutToChangeProperty(). Similarly,
      * either by calling endChange(), or in the destructor, the Transaction
      * automatically calls PropertyInterface::notifyPropertyChanged().
      *
      * This way, the PropertyInterface can track Property changes. For instance,
      * this is useful for automatically providing proper undo/redo support.
      */
     class Transaction
     {
     public:
         /**
          * Constructor, calling PropertyInterface::notifyAboutToChangeProperty().
          */
         Transaction(Property * prop);
 
         /**
          * Destructor, calling PropertyInterface::notifyPropertyChanged().
          */
         ~Transaction();
 
         /**
          * End the transaction earlier. Will call PropertyInterface::notifyPropertyChanged()
          * as well. However, the destructor then will do nothing.
          */
         void endChange();
 
     private:
         Property * m_property = nullptr;
     };
 
 private:
     // pimpl data pointer
     PropertyPrivate * const d;
 };
 
 } //namespace core
 } //namespace tikz
 
 #endif // TIKZ_CORE_ABSTRACT_PROPERTY_H
 
 // kate: indent-width 4; replace-tabs on;