Events:CTK-Hackfest-2010/SlicerQtPluginArchitecture - Revision history

JChris.FillionR: /* Big picture */

2010-03-08T07:11:05Z

Big picture

JChris.FillionR: /* Concrete example(s) */

2010-03-08T07:10:28Z

Concrete example(s)

JChris.FillionR: /* Under the hood */

2010-03-08T07:09:18Z

Under the hood

JChris.FillionR: /* Under the hood */

2010-03-08T07:07:42Z

Under the hood

JChris.FillionR: /* Big picture */

2010-03-08T07:00:39Z

Big picture

JChris.FillionR: Created page with '= Goal = * Provide a cross-platform plugin architecture * Modular and extensible = Big picture = * a Factory manages a collection of Factory items * Factory Item provides load()…'

2010-03-08T06:58:52Z

Created page with '= Goal = * Provide a cross-platform plugin architecture * Modular and extensible = Big picture = * a Factory manages a collection of Factory items * Factory Item provides load()…'

New page

= Goal =
* Provide a cross-platform plugin architecture
* Modular and extensible

= Big picture =
* a Factory manages a collection of Factory items
* Factory Item provides load() and instanciate() methods
* Factory provided registerItems() and load(key) methods

= Under the hood =

* The Qt layer
** QPlugin (from Qt docmentation ... )
*** QPluginLoader checks that a plugin is linked against the same version of Qt as the application.
*** QPluginLoader provides direct access to a root component object (instance()), instead of forcing you to resolve a C function manually.
*** In order to speed up loading and validation of plugins, some of the information that is collected during loading is cached in persistent memory (through QSettings).
** QLibrary
** QObject / Object

* The CTK layer
** Base class: qCTKAbstractFactory
<pre>
template<typename BaseClassType>
class qCTKAbstractFactory
{
...
public:
explicit qCTKAbstractFactory();
virtual ~qCTKAbstractFactory();
virtual void printAdditionalInfo();

/// Return factory name
virtual QString name()const = 0;

/// Create an instance of the object
virtual BaseClassType * instantiate(const QString& itemKey);

/// Uninstanciate the object
void uninstantiate(const QString& itemKey);

/// Get list of all registered item names
QStringList names() const;

/// Register items with the factory
/// Method provided for convenience - Should be overloaded in subclasse
virtual void registerItems(){}

protected:

/// Call the load method associated with the item.
/// If succesfully loaded, add it to the internal map.
bool registerItem(const QSharedPointer<qCTKAbstractFactoryItem<BaseClassType> > & item);

/// Get a Factory item given its itemKey. Return 0 if any.
qCTKAbstractFactoryItem<BaseClassType> * item(const QString& itemKey)const;

private:
...
};
</pre>

** 3 kind of factory:
*** qCTKAbstractLibraryFactory
*** qCTKAbstractObjectFactory
*** qCTKAbstractPluginFactory

** A factory manage a collection of qCTKAbstractFactoryItem.
<pre>
template<typename BaseClassType>
class qCTKAbstractFactoryItem
{
public:
explicit qCTKAbstractFactoryItem(const QString& key);

virtual QString loadErrorString()const;
virtual bool load() = 0;
BaseClassType* instantiate();
bool instantiated();
QString key();
virtual void uninstantiate();
protected:
virtual BaseClassType* instanciator() = 0;
BaseClassType* Instance;
private:
QString Key;
};
</pre>

* Concrete example(s)
All modules are based on qSlicerAbstractModule
qSlicerAbstractModule provided methods:
** logic(): This method allows to get a pointer to the ModuleLogic. If no moduleLogic already exists, one will be created calling 'createLogic' method
** widgetRepresentation(): This method allows to get a pointer to the WidgetRepresentation. If no WidgetRepresentation already exists, one will be created calling 'createWidgetRepresentation' method.

** qSlicerCoreModuleFactory:

*** registerItems -> registerCoreModule -> N * registerCoreModule -> extractName -> registerObject -> registerItem(moduleName)
<pre>
void qSlicerCoreModuleFactory::registerItems()
{
QCTK_D(qSlicerCoreModuleFactory);
d->registerCoreModule<qSlicerTransformsModule>();
d->registerCoreModule<qSlicerCamerasModule>();
}
</pre>

** qSlicerLoadableModuleFactory
*** registerItems -> use QDirIterator -> extractName -> registerPlugin(path, moduleName)
<pre>
template<typename BaseClassType>
bool qCTKFactoryPluginItem<BaseClassType>::load()
{
this->Loader.setFileName(this->path());
return this->Loader.load();
}
</pre>
<pre>
template<typename BaseClassType>
BaseClassType* qCTKFactoryPluginItem<BaseClassType>::instanciator()
{
//qDebug() << "PluginItem::instantiate - name:" << this->path();
QObject * object = this->Loader.instance();
if (!object)
{
qWarning() << "Failed to instantiate plugin:" << this->path();
return 0;
}
BaseClassType* castedObject = qobject_cast<BaseClassType*>(object);
if (!castedObject)
{
qWarning() << "Failed to access interface [" << BaseClassType::staticMetaObject.className()
<< "] in plugin:" << this->path();
delete object; // Clean memory
return 0;
}
return castedObject;
}
</pre>

** qSlicerCLILoadableModuleFactory
*** registerItems -> use QDirIterator -> extractName -> registerLibrary(path, moduleName)
<pre>
void qCTKFactoryLibraryItem<BaseClassType>::resolve()
{
foreach(const QString& symbol, this->Symbols)
{
// Sanity checks
if (symbol.isEmpty())
{
continue;
}

// Make sure the symbols haven't been registered
if (this->ResolvedSymbols.contains(symbol))
{
qWarning() << "Symbol '" << symbol << "' already resolved - Path:" << this->Path;
continue;
}

void * resolvedSymbol = this->Library.resolve(symbol.toLatin1());
if (!resolvedSymbol)
{
qWarning() << "Failed to resolve symbol '" << symbol << "' - Path:" << this->Path;
}
this->ResolvedSymbols[symbol] = resolvedSymbol;
}
}
</pre>

@@ Line 7: / Line 7: @@
 * Factory Item provides load() and instanciate() methods
 * Factory provides registerItems() and load(key) methods
 = Under the hood =

@@ Line 88: / Line 88: @@
 == Concrete example(s) ==
-All modules are based on qSlicerAbstractModule
+* All modules are based on qSlicerAbstractModule which provides:
-qSlicerAbstractModule provided methods:
+** logic(): This method allows to get a pointer to the ModuleLogic. If no moduleLogic already exists, one will be created calling 'createLogic' method
-* logic(): This method allows to get a pointer to the ModuleLogic. If no moduleLogic already exists, one will be created calling 'createLogic' method
+** widgetRepresentation(): This method allows to get a pointer to the WidgetRepresentation. If no WidgetRepresentation already exists, one will be created calling 'createWidgetRepresentation' method.
 * qSlicerCoreModuleFactory:

@@ Line 10: / Line 10: @@
 = Under the hood =
-* The Qt layer
+== The Qt layer ==
-** QPlugin [http://doc.trolltech.com/4.6-snapshot/qpluginloader.html] [http://doc.trolltech.com/4.6-snapshot/qtplugin.html] (from Qt docmentation ... )
+* QPlugin [http://doc.trolltech.com/4.6-snapshot/qpluginloader.html] [http://doc.trolltech.com/4.6-snapshot/qtplugin.html] (from Qt docmentation ... )
-*** QPluginLoader checks that a plugin is linked against the same version of Qt as the application.
+** QPluginLoader checks that a plugin is linked against the same version of Qt as the application.
-*** QPluginLoader provides direct access to a root component object (instance()), instead of forcing you to resolve a C function manually.
+** QPluginLoader provides direct access to a root component object (instance()), instead of forcing you to resolve a C function manually.
-*** In order to speed up loading and validation of plugins, some of the information that is collected during loading is cached in persistent memory (through QSettings).
+** In order to speed up loading and validation of plugins, some of the information that is collected during loading is cached in persistent memory (through QSettings).
-** QLibrary [http://doc.trolltech.com/4.6-snapshot/qlibrary.html]
+* QLibrary [http://doc.trolltech.com/4.6-snapshot/qlibrary.html]
-** QObject / Object
+* QObject / Object
-* The CTK layer
+== The CTK layer ==
-** Base class: qCTKAbstractFactory
+* Base class: qCTKAbstractFactory
 <pre>
 template<typename BaseClassType>
@@ Line 60: / Line 60: @@
 </pre>
-** 3 kind of factory:
+* 3 kind of factory:
-*** qCTKAbstractLibraryFactory
+** qCTKAbstractLibraryFactory
-*** qCTKAbstractObjectFactory
+** qCTKAbstractObjectFactory
-*** qCTKAbstractPluginFactory
+** qCTKAbstractPluginFactory
-** A factory manage a collection of qCTKAbstractFactoryItem.
+* A factory manage a collection of qCTKAbstractFactoryItem.
 <pre>
 template<typename BaseClassType>
@@ Line 87: / Line 87: @@
 </pre>
-* Concrete example(s)
+== Concrete example(s) ==
 All modules are based on qSlicerAbstractModule
 qSlicerAbstractModule provided methods:
@@ Line 93: / Line 93: @@
 * widgetRepresentation(): This method allows to get a pointer to the WidgetRepresentation. If no WidgetRepresentation already exists, one will be created calling 'createWidgetRepresentation' method.
-** qSlicerCoreModuleFactory:
+* qSlicerCoreModuleFactory:
 ** registerItems -> registerCoreModule -> N * registerCoreModule -> extractName -> registerObject -> registerItem(moduleName)
 <pre>
 void qSlicerCoreModuleFactory::registerItems()
@@ Line 105: / Line 104: @@
 </pre>
-** qSlicerLoadableModuleFactory
+* qSlicerLoadableModuleFactory
-*** registerItems -> use QDirIterator -> extractName -> registerPlugin(path, moduleName)
+** registerItems -> use QDirIterator -> extractName -> registerPlugin(path, moduleName)
 <pre>
 template<typename BaseClassType>
@@ Line 138: / Line 137: @@
 </pre>
-** qSlicerCLILoadableModuleFactory
+* qSlicerCLILoadableModuleFactory
-*** registerItems -> use QDirIterator -> extractName -> registerLibrary(path, moduleName)
+** registerItems -> use QDirIterator -> extractName -> registerLibrary(path, moduleName)
 <pre>
 void qCTKFactoryLibraryItem<BaseClassType>::resolve()