Commit 238a2e53 authored by Sebastian Eichelbaum's avatar Sebastian Eichelbaum

[CHANGE] - added more documentation to template module

parent 900fda26
......@@ -138,7 +138,6 @@ public:
TS_ASSERT_EQUALS( 0, dh->m_subjects.size() ); // note: this is 2 since the datahandler always provides a default subject
......@@ -38,42 +38,100 @@
// initialize members
// In the constructor, you can initialize your members and all this stuff. You must not initialize connectors or properties here! You also
// should avoid doing computationally expensive stuff, since every module has its own thread which is intended to be used for such calculations.
// Please keep in mind, that every member initialized here is also initialized in the prototype, which may be a problem if the member is large,
// and therefore, wasting a lot of memory in your module's prototype instance.
// cleanup
// Cleanup!
boost::shared_ptr< WModule > WMTemplate::factory() const
// To properly understand what this is, we need to have a look at how module instances get created. At first, if you are not familiar with the
// design patterns "Prototype", "Abstract Factory" and "Factory Method" you should probably read about them first. For short: while the kernel
// is starting up, it also creates an instance of WModuleFactory, which creates a prototype instance of every module that can be loaded.
// These prototypes are then used to create new instances of modules, check compatibility of modules and identify the type of modules.
// If someone, in most cases the module container, wants a new instance of a module with a given prototype, it asks the factory class for it,
// which uses the prototype's factory() method. Since the method is virtual, it returns a module instance, created with the correct type.
// A prototype itself is an instance of your module, with the constructor run, as well as connectors() and properties(). What does this mean
// to your module? Unlike the real "Prototype"- Design pattern, the module prototypes do not get cloned to retrieve a new instance,
// they get constructed using "new" and this factory method.
// Here is a short overview of the lifetime of a module instance:
// * constructor
// * connectors()
// * properties()
// * now isInitialized() will return true
// * the module will be associated with a container
// * now isAssociated() will return true
// o isUsable() will return true
// * after it got added, moduleMain() will be called
// * run, run, run, run
// * notifyStop gets called
// * moduleMain() should end
// * destructor
// So you always have to write this method and always return a valid pointer to an object of your module class.
// Never initialize something else in here!
return boost::shared_ptr< WModule >( new WMTemplate() );
const std::string WMTemplate::getName() const
// specify your module name here
// Specify your module name here. This name must be UNIQUE!
return "Template";
const std::string WMTemplate::getDescription() const
// specify your module description here. Be detailed. This text is read by the user.
// Specify your module description here. Be detailed. This text is read by the user.
return "This module is intended to be a module template and an example for writing modules.";
void WMTemplate::connectors()
// initialize connectors
// How will your module know on which data it should work? Through its input connector(s). How will other modules get to know about your
// calculated output data? Through your output connector(s). Simple isn't it? You may assume your module as some kind of function, as in
// common programming languages, where your connectors denote its function signature. The method "connectors()" is for initializing your
// connectors, your function signature. Now, a short excursion on how the module container and kernel knows which connector can be connected
// to which. Generally, there are only two types of connectors available for your usage: WModuleInputData and WModuleOutputData and they can
// only be connected to each other. So, it is not possible to connect an input with an input, nor an output with an output. Both of them are
// template classes and therefore are associated with a type. This type determines if an input connector is compatible with an output connector.
// A simple example: assume you have a class hierarchy:
// Initialize your connectors here. Give them proper names and use the type your module will create or rely on. Do not use types unnecessarily
// high in class hierarchy. The list of your connectors is fixed after connectors() got called. As in common imperative programming languages
// the function signature can not be changed during runtime (which, in our case, means after connectors() got called).
// Here is an example of how to create connectors. This module wants to have an input connector. This connector is defined by the type of
// data that should be transferred, an module-wide unique name and a proper description:
m_input = boost::shared_ptr< WModuleInputData < WDataSetSingle > >(
new WModuleInputData< WDataSetSingle >( shared_from_this(),
"in", "The dataset to display" )
// add it to the list of connectors. Please note, that a connector NOT added via addConnector will not work as expected.
// This creates an input connector which can receive WDataSetSingle. It will never be able to connect to output connectors providing just a
// WDataSet (which is the father class of WDataSetSingle), but it will be able to be connected to an output connector with a type derived
// from WDataSetSingle.
// As properties, every connector needs to be added to the list of connectors.
addConnector( m_input );
// Now, lets add an output connector. We want to provide data calculated here to other modules. The output connector is initialized the same
// way as input connectors. You need the type, the module-wide unique name and the description. The type you specify here also determines
// which input connectors can be connected to this output connector: only connectors with a type equal or lower in class hierarchy.
m_output = boost::shared_ptr< WModuleOutputData < WDataSetSingle > >(
new WModuleOutputData< WDataSetSingle >( shared_from_this(),
"out", "The calculated dataset" )
// As above: make it known.
addConnector( m_output );
// call WModules initialization
......@@ -201,12 +259,11 @@ void WMTemplate::moduleMain()
// This way you can ensure you always have valid data available.
// Here we collect our properties. You, as with input connectors, always check if a property really has changed. You most probably do not
// want to check properties which are used exclusively inside the update callback of your OSG node. As the properties are thread-safe, the update
// callback can check them and apply it correctly to your visualization.
// want to check properties which are used exclusively inside the update callback of your OSG node. As the properties are thread-safe, the
// update callback can check them and apply it correctly to your visualization.
// To check whether a property changed, WPropertyVariable provides a changed() method which is true whenever the property has changed.
// Please note: creating the property with addProperty( ... ) will set changed to true.
......@@ -223,9 +280,8 @@ void WMTemplate::moduleMain()
if ( m_aString->changed() )
// This is a simple example for doing an operation which is depends on all, but m_anFile, properties.
debugLog() << "Doing an operation not modifying the OSG node ... ";
debugLog() << "m_anString: " << m_aString->get( true );
debugLog() << "Current dataset: " << m_dataSet->getFileName() << " with name: " << m_dataSet->getName();
debugLog() << "Doing an operation basing on m_aString ... ";
debugLog() << "m_aString: " << m_aString->get( true );
// This example code now shows how to modify your OSG nodes basing on changes in your dataset or properties.
......@@ -273,6 +329,45 @@ void WMTemplate::moduleMain()
WKernel::getRunningKernel()->getGraphicsEngine()->getScene()->insert( m_rootNode );
// Now we updated the visualization after the dataset has changed. Your module might also calculate some other datasets basing on the
// input data.
if ( dataChanged )
debugLog() << "Data changed. Recalculating output.";
// Calculate your new data here. This example just forwards the input to the output ;-).
boost::shared_ptr< WDataSetSingle > newData = m_dataSet;
// Doing a lot of work without notifying the user visually is not a good idea. So how is it possible to report progress? Therefore,
// the WModule class provides a member m_progress which is of type WPropgressCombiner. You can create own progress objects and count
// them individually. The m_progress combiner provides this information to the GUI and the user.
// Here is a simple example:
int steps = 10;
boost::shared_ptr< WProgress > progress1 = boost::shared_ptr< WProgress >( new WProgress( "Doing work 1", steps ) );
m_progress->addSubProgress( progress1 );
for ( int i = 0; i < steps; ++i )
sleep( 1 );
// This creates a progress object with a name and a given number of steps. Your work loop can now increment the progress object. The
// progress combiner m_progress collects the progress and provides it to the GUI. When finished, the progress MUST be marked as
// finished using finish(). It is no problem to have several progress objects at the same time!
// Sometimes, the number of steps is not known. WProgress can also handle this. Simply leave away the last parameter (the number of
// steps. As with the other progress, you need to add it to the modules progress combiner and you need to mark it as finished with
// finish() if you are done with your work.
boost::shared_ptr< WProgress > progress2 = boost::shared_ptr< WProgress >( new WProgress( "Doing work 2" ) );
m_progress->addSubProgress( progress2 );
sleep( 2 );
// How to set the data to the output and how to notify other modules about it?
m_output->updateData( newData );
// This sets the new data to the output connector and automatically notifies all modules connected to your output.
// At this point, the container managing this module signalled to shutdown. The main loop has ended and you should clean up. Always remove
......@@ -295,8 +390,14 @@ void WMTemplate::SafeUpdateCallback::operator()( osg::Node* node, osg::NodeVisit
traverse( node, nv );
bool WMTemplate::StringLength::accept( boost::shared_ptr< WPropertyVariable< WPVBaseTypes::PV_STRING > > /* property */, WPVBaseTypes::PV_STRING value )
bool WMTemplate::StringLength::accept( boost::shared_ptr< WPropertyVariable< WPVBaseTypes::PV_STRING > > /* property */,
WPVBaseTypes::PV_STRING value )
// This method gets called everytime the m_aString property is going to be changed. It can decide whether the new value is valid or not. If
// the method returns true, the new value is set. If it returns false, the value is rejected.
// Note: always use WPVBaseTypes when specializing the WPropertyVariable template.
// simple example: just accept string which are at least 5 chars long and at most 10.
return ( value.length() <= 10 ) && ( value.length() >= 5 );
......@@ -101,6 +101,11 @@ private:
boost::shared_ptr< WModuleInputData< WDataSetSingle > > m_input;
* The output connector used to provide the calculated data to other modules.
boost::shared_ptr< WModuleOutputData< WDataSetSingle > > m_output;
* This is a pointer to the dataset the module is currently working on.
......@@ -148,7 +153,15 @@ private:
class SafeUpdateCallback : public osg::NodeCallback
public: // NOLINT
SafeUpdateCallback( WMTemplate* module ): m_module( module ) {};
* Constructor.
* \param module just set the creating module as pointer for later reference.
explicit SafeUpdateCallback( WMTemplate* module ): m_module( module )
* operator () - called during the update traversal.
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