xmlregionhandler.cc

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// Thu Feb 14 16:58:28 GMT 2002  by  nts

////////////////////////////////////////////////////////////////////////////////////
//                                                                                //
// class XMLRegionHandler : public DefaultHandler                                 //
//                                                                                //
// This class defines an interface to XML Region data as defined by the XML       //
// Schema namespace "http://www.cvg.cs.reading.ac.uk/ADVISOR" (the current name). //
//                                                                                //
// Similar in design to our ImageSource classes, some methods are pure virtual    //
// and the class should therefore not be instantiated directly.                   //
//                                                                                //
// The XMLRegionHandler class is derived from the XML SAX2 DefaultHandler class   //
// which is designed to ignore all requests.  We only redefine the methods that   //
// we need such that there is little overhead.                                    //
//                                                                                //
////////////////////////////////////////////////////////////////////////////////////

#include "XMLRegionHandler.h"

#include <util/XMLString.hpp>  // XMLString class with static character conversion methods
#include <sax2/Attributes.hpp>

#include "Region.h"
#include "RegionSet.h"
#include "text_output.h"

namespace ReadingPeopleTracker
{

//////////////////////////////////////////////////////////////////////////
//   Constructor and Destructor                                         //
//////////////////////////////////////////////////////////////////////////

XMLRegionHandler::XMLRegionHandler()
{
    // initialise variables to sensible values...
    frame_count = 0;
    parsing_level = 0;
    new_region = NULL;
    current_region_set = NULL;
    have_valid_region_set = false;
    region_set_has_been_queried = true;
}

XMLRegionHandler::~XMLRegionHandler()
{
    // nothing
}


//////////////////////////////////////////////////////////////////////////
//   Access function to query current region set                        //
//////////////////////////////////////////////////////////////////////////

RegionSet *XMLRegionHandler::get_current()
{
    // check whether the current_region_set is valid
    if (have_valid_region_set)
    {
	// remember that RegionSet has been queried
	region_set_has_been_queried = true;
	
	// return current complete set
	return current_region_set;
    }
    
    // we have no complete RegionSet yet!
    //   give an error message and return an empty new RegionSet:
    cerror << " XMLRegionHandler::get_current() : RegionSet queried before it was complete "
	   << endl;
    
    return new RegionSet;
}


//////////////////////////////////////////////////////////////////////////
//  Implementation of the SAX2 DocumentHandler interface                //
//////////////////////////////////////////////////////////////////////////

void XMLRegionHandler::startDocument()
{
     // initialise parsing level to 0 (toplevel)
     parsing_level = 0;
}

void XMLRegionHandler::endDocument()
{
    // signal that the RegionSet current_regions we have is now complete
    //   but is has not been queried using get_current() yet
    region_set_has_been_queried = false;
    have_valid_region_set = true;
    
    assert (parsing_level == 0);   // check for valid XML document structure
    
    // if the region set has not been collected via get_current() it will
    // have to be de-allocated. 
}

void XMLRegionHandler::startElement(const XMLCh *const uri,
				    const XMLCh *const localname,
				    const XMLCh *const qname,
				    const XERCES_CPP_NAMESPACE::Attributes &attributes)
{
    // There are currently 5 valid elements we recognise (level in brackets) :-
    //   MD_blob_frame (0), blob(1), info2d(2), info3d(2), occlusion(2).
    //   All data (coordinates etc) is given in attributes.
    //   see http://www.cvg.cs.reading.ac.uk/~nts/ADVISOR/motion_detector.xsd
    char *element_name = XMLString::transcode(localname);
    
    if (strcasecmp(element_name, "md_blob_frame") == 0)  // matched this element name?
    {
	// call specific function
	handle_frame(&attributes);
	
	// we have gone one level further into the document
	parsing_level++;  
	return;
    }
    
    if (strcasecmp(element_name, "blob") == 0)  // matched this element name?
    {
	// call specific function
	handle_blob(&attributes);
	
	// we have gone one level further into the document
	parsing_level++;  
	return;
    }
    
    if (strcasecmp(element_name, "info2d") == 0)  // matched this element name?
    {
	// call specific function
	handle_info2d(&attributes);
	
	// we have gone one level further into the document
	parsing_level++;  
	return;
    }
    
    if (strcasecmp(element_name, "info3d") == 0)  // matched this element name?
    {
	// call specific function
	handle_info3d(&attributes);
	
	// we have gone one level further into the document
	parsing_level++;  
	return;
    }
    
    if (strcasecmp(element_name, "occlusion") == 0)  // matched this element name?
    {
	// call specific function
	handle_occlusion(&attributes);
	
	// we have gone one level further into the document
	parsing_level++;  
	return;
    }

    // if we end up here, the element name was not matched
    //   give an error message and ignore the data
    cerror << " XMLRegionHandler::startElement(): Unknown XML element