ParaQ:API

Overview

We need to establish the architecture for how the GUI code interacts with the Server Manager.

Goals

The goals of designing this architecture are:

• Establish a general method for how the GUI talks to the Server Manager.
• Provide a way for the GUI to update correctly if a scripting client is modifying the server.
• Be designed to minimize traffic with the server.
• Decouple GUI from Server Manager to allow using of Qt Designer.
• To provide functionality such that multiple inheritance of VTK & Qt objects is not necessary (toolkits have different object management schemes).
• Allow GUI to control behavior. Meaning, Server Manager or API doesn't impose behavior on the GUI.

Use Cases

Description: Use case of API linking SM properties with Qt properties. Object controller controls behavior of GUI panel (vtkSphereSource). GUI panel could be generated or designed. API takes properties to set in bulk to minimize possible network traffic.

Description: Use case of a pipeline inspector/browser. API provides GUI with events for proxy creation. API also provides GUI with events for input/output connections between proxies. GUI calls SM directly to manipulate the pipeline.

Description: Use case of linked views. Can linked views be thought of as linked properties and a view watching for property changes?

Histogram Use case: Histogram will watch for modified events and then pull data through pipeline to display histogram.

The SM API

The Server Manager API contains these basic components:

• Proxy
• Property
• Domain
• Data

The Qt-SM API

The Qt interface to SM for the GUI will have functions like the following. This is not set in stone yet.

{
  signals:
    // signal from SM that a proxy was created
    void ProxyCreated(vtkSMProxy* Proxy);

    // signal from SM that a proxy was deleted
    void ProxyDeleted(vtkSMProxy* Proxy);

    // signal from SM that a proxy has an added input
    void ProxyInputAdded(vtkSMProxy* Proxy, vtkSMProxy* Input);

    // signal from SM that a proxy has a removed input
    void ProxyInputRemoved(vtkSMProxy* Proxy, vtkSMProxy* Input);

    // signal from SM that a proxy has an added output
    void ProxyOutputAdded(vtkSMProxy* Proxy, vtkSMProxy* Output);

    // signal from SM that a proxy has a removed output
    void ProxyOutputRemoved(vtkSMProxy* Proxy, vtkSMProxy* Output);


 public:

    // Set properties for a proxy.  UpdateVTKObjects is automatically called.
    void SetProperties(vtkSMProxy* Proxy, QList<vtkSMProperty*>, QList<QVariant>);

    // Get properties for a proxy.
    void GetProperties(vtkSMProxy* Proxy, QList<vtkSMProperty*>, QList<QVariant>);



    // Property linking
    // If a vtkSMProperty is linked to multiple QObjects' properties, this API
    // will query the Server Manager once for the data and give it to all QObjects.

    // Link a property of a proxy to a property of a QObject.
    // The QObject property follows the vtkSMProperty.
    void LinkPropertyTo(vtkSMProxy* Proxy, vtkSMProperty* Property, int Index,
                           QObject* qObject, const char* qProperty);

    // Unlink a property of a proxy from a property of a QObject.
    void UnlinkPropertyFrom(vtkSMProxy* Proxy, vtkSMProperty* Property, int Index,
                           QObject* qObject, const char* qProperty);

    // Link a property of a QObject to a property of a proxy.
    // The vtkSMProperty follows the QObject's property.
    void LinkPropertyTo(QObject* qObject, const char* qProperty,
                        vtkSMProxy* Proxy, vtkSMProperty* Property, int Index);

    // Unlink a property of a QObject from a property of a proxy.
    void UnlinkPropertyFrom(QObject* qObject, const char* qProperty,
                        vtkSMProxy* Proxy, vtkSMProperty* Property, int Index);


    // Domain linking
    // link a vtkSMDomain to a QObject's property.  The QObject property must be a QVariant.
    void LinkDomain(vtkSMDomain* Domain, QObject* qObject, const char* qProperty);

    // unlink a vtkSMDomain from a QObject's property.  The QObject property must be a QVariant.
    void UnLinkDomain(vtkSMDomain* Domain, QObject* qObject, const char* qProperty);

}

Assumptions

It is assumed that Compound Filters, Linked Views, and Histogram Data will be implemented in the Server Manager and the GUI can use the aforementioned events to get updated when those change.

Implementation Details

The Event Relay will contain Qt signals that Qt objects in the GUI can connect to. The signal signatures will be Qt friendly. For example, a property changed signal will have parameters of which property of an object changed and what the value of the property is. The Event Relay will translate events if necessary into a form the GUI would like. For example, if the Server Manager sends an event about object connections, the Event Relay will change that into an object input/output connection signal. In other words, Server Manager level events will be translated to object level events. The vtkEventQtSlotConnect class will be used by the Event Relay. It contains a generic signal signature to connect to. The Event Relay will change the parameters into ParaQ frirendly parameters.