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Per Object Data

# Overview

To help developers organizing their data which belongs to specific objects, OpenFlipper provides the PerObjectData class. When you derive your classes from the PerObjectData base class, you can attach it to every object in the scene. This way OpenFlipper takes care of destructing the object, when the corresponding object gets removed and the developer has a permanent storage associated with the object.

# Creating your own class

To use the system, just derive your class from the PerObjectData base class:

#include <OpenFlipper/common/perObjectData.hh>
class DataClass : public PerObjectData
{
public :
// Constructor
DataClass();
// Destructor
~DataClass();
// Copy function (Implement this copy function to create a hard copy of your class)
PerObjectData* copyPerObjectData();
// Your data/functions
};

One important virtual function is the virtual PerObjectData::copyPerObjectData() function. In this function you have to create a hard copy of your class. This hard copy is used by OpenFlippers backup system to take a full snapshot of all Objects and their associated data. This way you can easily store your plugin state for a specific object in an PerObjectData. If the used than performs undo or redo operations, the attached data will also be switched and your states will be kept persistent with the current state of the object.

# Attaching the per object data to objects in the scene.

The corresponding functions are implemented in the BaseObject (here). The function to attach it is called BaseObject::setObjectData(). It gets a name(QString) which should start with the plugin name that generated the data and a reasonable description of the data. To get a pointer to a specific PerObjectDAta attached to the object, call BaseObject::objectData().