src/core/qgsproject.cpp

Go to the documentation of this file.

/***************************************************************************
                          qgsproject.cpp -  description
                             -------------------
  begin                : July 23, 2004
  copyright            : (C) 2004 by Mark Coletti
  email                : mcoletti at gmail.com
***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "qgsproject.h"

#include <deque>
#include <memory>

#include "qgslogger.h"
#include "qgsrectangle.h"
#include "qgsvectorlayer.h"
#include "qgsrasterlayer.h"
#include "qgsmaplayerregistry.h"
#include "qgsexception.h"
#include "qgsprojectproperty.h"
#include "qgsprojectfiletransform.h"
#include "qgsprojectversion.h"
#include "qgspluginlayer.h"
#include "qgspluginlayerregistry.h"

#include <QApplication>
#include <QFileInfo>
#include <QDomNode>
#include <QObject>
#include <QTextStream>

// canonical project instance
QgsProject * QgsProject::theProject_;

static
QStringList makeKeyTokens_( QString const &scope, QString const &key )
{
  // XXX - debugger probes
  //const char * scope_str = scope.toLocal8Bit().data();
  //const char * key_str   = key.toLocal8Bit().data();

  QStringList keyTokens = QStringList( scope );
  keyTokens += key.split( '/', QString::SkipEmptyParts );

  // be sure to include the canonical root node
  keyTokens.push_front( "properties" );

  return keyTokens;
} // makeKeyTokens_




static
QgsProperty * findKey_( QString const & scope,
                        QString const & key,
                        QgsPropertyKey &   rootProperty )
{
  QgsPropertyKey * currentProperty = &rootProperty;
  QgsProperty * nextProperty;           // link to next property down hiearchy

  QStringList keySequence = makeKeyTokens_( scope, key );

  while ( ! keySequence.isEmpty() )
  {
    // if the current head of the sequence list matches the property name,
    // then traverse down the property hierarchy
    if ( keySequence.first() == currentProperty->name() )
    {
      // remove front key since we're traversing down a level
      keySequence.pop_front();

      // if we have only one key name left, then return the key found
      if ( 1 == keySequence.count() )
      {
        return currentProperty->find( keySequence.front() );

      }
      // if we're out of keys then the current property is the one we
      // want; i.e., we're in the rate case of being at the top-most
      // property node
      else if ( keySequence.isEmpty() )
      {
        return currentProperty;
      }
      else if (( nextProperty = currentProperty->find( keySequence.first() ) ) )
      {
        if ( nextProperty->isKey() )
        {
          currentProperty = dynamic_cast<QgsPropertyKey*>( nextProperty );
        }
        // it may be that this may be one of several property value
        // nodes keyed by QDict string; if this is the last remaining
        // key token and the next property is a value node, then
        // that's the situation, so return the currentProperty
        else if ( nextProperty->isValue() && ( 1 == keySequence.count() ) )
        {
          return currentProperty;
        }
        else            // QgsPropertyValue not Key, so return null
        {
          return 0x0;
        }
      }
      else                // if the next key down isn't found
      {                   // then the overall key sequence doesn't exist
        return 0x0;
      }
    }
    else
    {
      return 0x0;
    }
  }

  return 0x0;
} // findKey_



static
QgsProperty * addKey_( QString const & scope,
                       QString const & key,
                       QgsPropertyKey * rootProperty,
                       QVariant value )
{
  QStringList keySequence = makeKeyTokens_( scope, key );

  // cursor through property key/value hierarchy
  QgsPropertyKey * currentProperty = rootProperty;

  QgsProperty * newProperty; // link to next property down hiearchy

  while ( ! keySequence.isEmpty() )
  {
    // if the current head of the sequence list matches the property name,
    // then traverse down the property hierarchy
    if ( keySequence.first() == currentProperty->name() )
    {
      // remove front key since we're traversing down a level
      keySequence.pop_front();

      // if key sequence has one last element, then we use that as the
      // name to store the value
      if ( 1 == keySequence.count() )
      {
        currentProperty->setValue( keySequence.front(), value );
        return currentProperty;
      }
      // we're at the top element if popping the keySequence element
      // will leave it empty; in that case, just add the key
      else if ( keySequence.isEmpty() )
      {
        currentProperty->setValue( value );

        return currentProperty;
      }
      else if (( newProperty = currentProperty->find( keySequence.first() ) ) )
      {
        currentProperty = dynamic_cast<QgsPropertyKey*>( newProperty );

        if ( currentProperty )
        {
          continue;
        }
        else            // QgsPropertyValue not Key, so return null
        {
          return 0x0;
        }
      }
      else                // the next subkey doesn't exist, so add it
      {
        newProperty = currentProperty->addKey( keySequence.first() );

        if ( newProperty )
        {
          currentProperty = dynamic_cast<QgsPropertyKey*>( newProperty );
        }
        continue;
      }
    }
    else
    {
      return 0x0;
    }
  }

  return 0x0;

} // addKey_



static
void removeKey_( QString const & scope,
                 QString const & key,
                 QgsPropertyKey & rootProperty )
{
  QgsPropertyKey * currentProperty = &rootProperty;

  QgsProperty * nextProperty = NULL;   // link to next property down hiearchy
  QgsPropertyKey * previousQgsPropertyKey = NULL; // link to previous property up hiearchy

  QStringList keySequence = makeKeyTokens_( scope, key );

  while ( ! keySequence.isEmpty() )
  {
    // if the current head of the sequence list matches the property name,
    // then traverse down the property hierarchy
    if ( keySequence.first() == currentProperty->name() )
    {
      // remove front key since we're traversing down a level
      keySequence.pop_front();

      // if we have only one key name left, then try to remove the key
      // with that name
      if ( 1 == keySequence.count() )
      {
        currentProperty->removeKey( keySequence.front() );
      }
      // if we're out of keys then the current property is the one we
      // want to remove, but we can't delete it directly; we need to
      // delete it from the parent property key container
      else if ( keySequence.isEmpty() )
      {
        previousQgsPropertyKey->removeKey( currentProperty->name() );
      }
      else if (( nextProperty = currentProperty->find( keySequence.first() ) ) )
      {
        previousQgsPropertyKey = currentProperty;
        currentProperty = dynamic_cast<QgsPropertyKey*>( nextProperty );

        if ( currentProperty )
        {
          continue;
        }
        else            // QgsPropertyValue not Key, so return null
        {
          return;
        }
      }
      else                // if the next key down isn't found
      {                   // then the overall key sequence doesn't exist
        return;
      }
    }
    else
    {
      return;
    }
  }

} // void removeKey_



struct QgsProject::Imp
{
  QFile file;

  QgsPropertyKey properties_;

  QString title;

  bool dirty;

  Imp()
      : title( "" ),
      dirty( false )
  {                             // top property node is the root
    // "properties" that contains all plug-in
    // and extra property keys and values
    properties_.name() = "properties"; // root property node always this value
  }

  void clear()
  {
    //QgsDebugMsg( "Clearing project properties Impl->clear();" );

    properties_.clearKeys();
    title = "";

    // reset some default project properties
    // XXX THESE SHOULD BE MOVED TO STATUSBAR RELATED SOURCE
    QgsProject::instance()->writeEntry( "PositionPrecision", "/Automatic", true );
    QgsProject::instance()->writeEntry( "PositionPrecision", "/DecimalPlaces", 2 );
    QgsProject::instance()->writeEntry( "Paths", "/Absolute", false );
  }

};  // struct QgsProject::Imp



QgsProject::QgsProject()
    : imp_( new QgsProject::Imp ), mBadLayerHandler( new QgsProjectBadLayerDefaultHandler() )
{
  // Set some default project properties
  // XXX THESE SHOULD BE MOVED TO STATUSBAR RELATED SOURCE
  writeEntry( "PositionPrecision", "/Automatic", true );
  writeEntry( "PositionPrecision", "/DecimalPlaces", 2 );
  writeEntry( "Paths", "/Absolute", false );
  // XXX writeEntry() makes the project dirty, but it doesn't make sense
  // for a new project to be dirty, so let's clean it up
  dirty( false );
} // QgsProject ctor



QgsProject::~QgsProject()
{
  delete mBadLayerHandler;

  // note that std::auto_ptr automatically deletes imp_ when it's destroyed
} // QgsProject dtor



QgsProject * QgsProject::instance()
{
  if ( !QgsProject::theProject_ )
  {
    QgsProject::theProject_ = new QgsProject;
  }

  return QgsProject::theProject_;
} // QgsProject * instance()




void QgsProject::title( QString const &title )
{
  imp_->title = title;

  dirty( true );
} // void QgsProject::title


QString const & QgsProject::title() const
{
  return imp_->title;
} // QgsProject::title() const


bool QgsProject::isDirty() const
{
  return imp_->dirty;
} // bool QgsProject::isDirty()


void QgsProject::dirty( bool b )
{
  imp_->dirty = b;
} // bool QgsProject::isDirty()



void QgsProject::setFileName( QString const &name )
{
  imp_->file.setFileName( name );

  dirty( true );
} // void QgsProject::setFileName( QString const & name )



QString QgsProject::fileName() const
{
  return imp_->file.fileName();
} // QString QgsProject::fileName() const



static void dump_( QgsPropertyKey const & topQgsPropertyKey )
{
  QgsDebugMsg( "current properties:" );

  topQgsPropertyKey.dump();
} // dump_




static
void
_getProperties( QDomDocument const &doc, QgsPropertyKey & project_properties )
{
  QDomNodeList properties = doc.elementsByTagName( "properties" );

  if ( properties.count() > 1 )
  {
    QgsDebugMsg( "there appears to be more than one ``properties'' XML tag ... bailing" );
    return;
  }
  else if ( properties.count() < 1 )  // no properties found, so we're done
  {
    return;
  }

  // item(0) because there should only be ONE
  // "properties" node
  QDomNodeList scopes = properties.item( 0 ).childNodes();

  if ( scopes.count() < 1 )
  {
    QgsDebugMsg( "empty ``properties'' XML tag ... bailing" );
    return;
  }

  QDomNode propertyNode = properties.item( 0 );

  if ( ! project_properties.readXML( propertyNode ) )
  {
    QgsDebugMsg( "Project_properties.readXML() failed" );
  }

#if 0
// DEPRECATED as functionality has been shoved down to QgsProperyKey::readXML()
  size_t i = 0;
  while ( i < scopes.count() )
  {
    QDomNode curr_scope_node = scopes.item( i );

    qDebug( "found %d property node(s) for scope %s",
            curr_scope_node.childNodes().count(),
            curr_scope_node.nodeName().utf8().constData() );

    QString key( curr_scope_node.nodeName() );

    QgsPropertyKey * currentKey =
      dynamic_cast<QgsPropertyKey*>( project_properties.find( key ) );

    if ( ! currentKey )
    {
      // if the property key doesn't yet exist, create an empty instance
      // of that key

      currentKey = project_properties.addKey( key );

      if ( ! currentKey )
      {
        qDebug( "%s:%d unable to add key", __FILE__, __LINE__ );
      }
    }

    if ( ! currentKey->readXML( curr_scope_node ) )
    {
      qDebug( "%s:%d unable to read XML for property %s", __FILE__, __LINE__,
              curr_scope_node.nodeName().utf8().constData() );
    }

    ++i;
  }
#endif
} // _getProperties




static void _getTitle( QDomDocument const &doc, QString & title )
{
  QDomNodeList nl = doc.elementsByTagName( "title" );

  title = "";                 // by default the title will be empty

  if ( !nl.count() )
  {
    QgsDebugMsg( "unable to find title element" );
    return;
  }

  QDomNode titleNode = nl.item( 0 );  // there should only be one, so zeroth element ok

  if ( !titleNode.hasChildNodes() ) // if not, then there's no actual text
  {
    QgsDebugMsg( "unable to find title element" );
    return;
  }

  QDomNode titleTextNode = titleNode.firstChild();  // should only have one child

  if ( !titleTextNode.isText() )
  {
    QgsDebugMsg( "unable to find title element" );
    return;
  }

  QDomText titleText = titleTextNode.toText();

  title = titleText.data();

} // _getTitle


static QgsProjectVersion _getVersion( QDomDocument const &doc )
{
  QDomNodeList nl = doc.elementsByTagName( "qgis" );

  if ( !nl.count() )
  {
    QgsDebugMsg( " unable to find qgis element in project file" );
    return QgsProjectVersion( 0, 0, 0, QString( "" ) );
  }

  QDomNode qgisNode = nl.item( 0 );  // there should only be one, so zeroth element ok

  QDomElement qgisElement = qgisNode.toElement(); // qgis node should be element
  QgsProjectVersion projectVersion( qgisElement.attribute( "version" ) );
  return projectVersion;
} // _getVersion



QPair< bool, QList<QDomNode> > QgsProject::_getMapLayers( QDomDocument const &doc )
{
  // Layer order is set by the restoring the legend settings from project file.
  // This is done on the 'readProject( ... )' signal

  QDomNodeList nl = doc.elementsByTagName( "maplayer" );

  // XXX what is this used for? QString layerCount( QString::number(nl.count()) );

  QString wk;

  QList<QDomNode> brokenNodes; // a list of Dom nodes corresponding to layers
  // that we were unable to load; this could be
  // because the layers were removed or
  // re-located after the project was last saved

  // process the map layer nodes

  if ( 0 == nl.count() )      // if we have no layers to process, bail
  {
    return qMakePair( true, brokenNodes ); // Decided to return "true" since it's
    // possible for there to be a project with no
    // layers; but also, more imporantly, this
    // would cause the tests/qgsproject to fail
    // since the test suite doesn't currently
    // support test layers
  }

  bool returnStatus = true;

  emit layerLoaded( 0, nl.count() );

  //Collect vector layers with joins.
  //They need to refresh join caches and symbology infos after all layers are loaded
  QList< QPair< QgsVectorLayer*, QDomElement > > vLayerList;

  for ( int i = 0; i < nl.count(); i++ )
  {
    QDomNode node = nl.item( i );
    QDomElement element = node.toElement();

    if ( element.attribute( "embedded" ) == "1" )
    {
      createEmbeddedLayer( element.attribute( "id" ), readPath( element.attribute( "project" ) ), brokenNodes, vLayerList );
      continue;
    }
    else
    {
      if ( !addLayer( element, brokenNodes, vLayerList ) )
      {
        returnStatus = false;
      }
    }
    emit layerLoaded( i + 1, nl.count() );
  }

  //Update field map of layers with joins and create join caches if necessary
  //Needs to be done here once all dependent layers are loaded
  QString errorMessage;
  QList< QPair< QgsVectorLayer*, QDomElement > >::iterator vIt = vLayerList.begin();
  for ( ; vIt != vLayerList.end(); ++vIt )
  {
    vIt->first->createJoinCaches();
    vIt->first->updateFieldMap();
    //for old symbology, it is necessary to read the symbology again after having the complete field map
    if ( !vIt->first->isUsingRendererV2() )
    {
      vIt->first->readSymbology( vIt->second, errorMessage );
    }
  }

  return qMakePair( returnStatus, brokenNodes );

} // _getMapLayers


bool QgsProject::addLayer( const QDomElement& layerElem, QList<QDomNode>& brokenNodes, QList< QPair< QgsVectorLayer*, QDomElement > >& vectorLayerList )
{
  QString type = layerElem.attribute( "type" );
  QgsDebugMsg( "Layer type is " + type );
  QgsMapLayer *mapLayer = NULL;

  if ( type == "vector" )
  {
    mapLayer = new QgsVectorLayer;
  }
  else if ( type == "raster" )
  {
    mapLayer = new QgsRasterLayer;
  }
  else if ( type == "plugin" )
  {
    QString typeName = layerElem.attribute( "name" );
    mapLayer = QgsPluginLayerRegistry::instance()->createLayer( typeName );
  }

  Q_CHECK_PTR( mapLayer );

  if ( !mapLayer )
  {
    QgsDebugMsg( "Unable to create layer" );

    return false;
  }

  // have the layer restore state that is stored in Dom node
  if ( mapLayer->readXML( layerElem ) && mapLayer->isValid() )
  {
    QList<QgsMapLayer *> myLayers;
    myLayers << mapLayer;
    QgsMapLayerRegistry::instance()->addMapLayers( myLayers );
    QgsVectorLayer* vLayer = qobject_cast<QgsVectorLayer*>( mapLayer );
    if ( vLayer && vLayer->vectorJoins().size() > 0 )
    {
      vectorLayerList.push_back( qMakePair( vLayer, layerElem ) );
    }
    return true;
  }
  else
  {
    delete mapLayer;

    QgsDebugMsg( "Unable to load " + type + " layer" );
    brokenNodes.push_back( layerElem );
    return false;
  }
}


bool QgsProject::read( QFileInfo const &file )
{
  imp_->file.setFileName( file.filePath() );

  return read();
} // QgsProject::read



bool QgsProject::read()
{
  clearError();

  std::auto_ptr< QDomDocument > doc =
    std::auto_ptr < QDomDocument > ( new QDomDocument( "qgis" ) );

  if ( !imp_->file.open( QIODevice::ReadOnly ) )
  {
    imp_->file.close();

    setError( tr( "Unable to open %1" ).arg( imp_->file.fileName() ) );

    return false;
  }

  // location of problem associated with errorMsg
  int line, column;
  QString errorMsg;

  if ( !doc->setContent( &imp_->file, &errorMsg, &line, &column ) )
  {
    // want to make this class as GUI independent as possible; so commented out
#if 0
    QMessageBox::critical( 0, tr( "Project File Read Error" ),
                           tr( "%1 at line %2 column %3" ).arg( errorMsg ).arg( line ).arg( column ) );
#endif

    QString errorString = tr( "Project file read error: %1 at line %2 column %3" )
                          .arg( errorMsg ).arg( line ).arg( column );

    QgsDebugMsg( errorString );

    imp_->file.close();

    setError( tr( "%1 for file %2" ).arg( errorString ).arg( imp_->file.fileName() ) );

    return false;
  }

  imp_->file.close();


  QgsDebugMsg( "Opened document " + imp_->file.fileName() );
  QgsDebugMsg( "Project title: " + imp_->title );

  // get project version string, if any
  QgsProjectVersion fileVersion =  _getVersion( *doc );
  QgsProjectVersion thisVersion( QGis::QGIS_VERSION );

  if ( thisVersion > fileVersion )
  {
    QgsLogger::warning( "Loading a file that was saved with an older "
                        "version of qgis (saved in " + fileVersion.text() +
                        ", loaded in " + QGis::QGIS_VERSION +
                        "). Problems may occur." );

    QgsProjectFileTransform projectFile( *doc, fileVersion );

    emit oldProjectVersionWarning( fileVersion.text() );
    QgsDebugMsg( "Emitting oldProjectVersionWarning(oldVersion)." );

    projectFile.dump();

    projectFile.updateRevision( thisVersion );

    projectFile.dump();

  }

  // before we start loading everything, let's clear out the current set of
  // properties first so that we don't have the properties from the previous
  // project still hanging around

  imp_->clear();
  mEmbeddedLayers.clear();

  // now get any properties
  _getProperties( *doc, imp_->properties_ );

  QgsDebugMsg( QString::number( imp_->properties_.count() ) + " properties read" );

  dump_( imp_->properties_ );


  // restore the canvas' area of interest

  // now get project title
  _getTitle( *doc, imp_->title );


  // get the map layers
  QPair< bool, QList<QDomNode> > getMapLayersResults =  _getMapLayers( *doc );

  // review the integrity of the retrieved map layers
  bool clean = getMapLayersResults.first;

  if ( !clean )
  {
    QgsDebugMsg( "Unable to get map layers from project file." );

    if ( ! getMapLayersResults.second.isEmpty() )
    {
      QgsDebugMsg( "there are " + QString::number( getMapLayersResults.second.size() ) + " broken layers" );
    }

    // we let a custom handler to decide what to do with missing layers
    // (default implementation ignores them, there's also a GUI handler that lets user choose correct path)
    mBadLayerHandler->handleBadLayers( getMapLayersResults.second, *doc );
  }

  // read the project: used by map canvas and legend
  emit readProject( *doc );

  // if all went well, we're allegedly in pristine state
  if ( clean )
    dirty( false );

  return true;

} // QgsProject::read





bool QgsProject::read( QDomNode & layerNode )
{
  QList<QDomNode> brokenNodes;
  QList< QPair< QgsVectorLayer*, QDomElement > > vectorLayerList;
  return addLayer( layerNode.toElement(), brokenNodes, vectorLayerList );
} // QgsProject::read( QDomNode & layerNode )



bool QgsProject::write( QFileInfo const &file )
{
  imp_->file.setFileName( file.filePath() );

  return write();
} // QgsProject::write( QFileInfo const & file )


bool QgsProject::write()
{
  clearError();

  // if we have problems creating or otherwise writing to the project file,
  // let's find out up front before we go through all the hand-waving
  // necessary to create all the Dom objects
  if ( !imp_->file.open( QIODevice::WriteOnly | QIODevice::Text | QIODevice::Truncate ) )
  {
    imp_->file.close();         // even though we got an error, let's make
    // sure it's closed anyway

    setError( tr( "Unable to save to file %1" ).arg( imp_->file.fileName() ) );
    return false;
  }
  QFileInfo myFileInfo( imp_->file );
  if ( !myFileInfo.isWritable() )
  {
    // even though we got an error, let's make
    // sure it's closed anyway
    imp_->file.close();
    setError( tr( "%1 is not writable. Please adjust permissions (if possible) and try again." )
              .arg( imp_->file.fileName() ) );
    return false;
  }

  QDomImplementation DomImplementation;

  QDomDocumentType documentType =
    DomImplementation.createDocumentType( "qgis", "http://mrcc.com/qgis.dtd",
                                          "SYSTEM" );
  std::auto_ptr < QDomDocument > doc =
    std::auto_ptr < QDomDocument > ( new QDomDocument( documentType ) );


  QDomElement qgisNode = doc->createElement( "qgis" );
  qgisNode.setAttribute( "projectname", title() );
  qgisNode.setAttribute( "version", QString( "%1" ).arg( QGis::QGIS_VERSION ) );

  doc->appendChild( qgisNode );

  // title
  QDomElement titleNode = doc->createElement( "title" );
  qgisNode.appendChild( titleNode );

  QDomText titleText = doc->createTextNode( title() );  // XXX why have title TWICE?
  titleNode.appendChild( titleText );

  // let map canvas and legend write their information
  emit writeProject( *doc );

  // within top level node save list of layers
  QMap<QString, QgsMapLayer*> & layers = QgsMapLayerRegistry::instance()->mapLayers();

  // Iterate over layers in zOrder
  // Call writeXML() on each
  QDomElement projectLayersNode = doc->createElement( "projectlayers" );
  projectLayersNode.setAttribute( "layercount", qulonglong( layers.size() ) );

  QMap<QString, QgsMapLayer*>::iterator li = layers.begin();
  while ( li != layers.end() )
  {
    //QgsMapLayer *ml = QgsMapLayerRegistry::instance()->mapLayer(*li);
    QgsMapLayer* ml = li.value();

    if ( ml )
    {
      QString externalProjectFile = layerIsEmbedded( ml->id() );
      QHash< QString, QPair< QString, bool> >::const_iterator emIt = mEmbeddedLayers.find( ml->id() );
      if ( emIt == mEmbeddedLayers.constEnd() )
      {
        ml->writeXML( projectLayersNode, *doc );
      }
      else //layer defined in an external project file
      {
        //only save embedded layer if not managed by a legend group
        if ( emIt.value().second )
        {
          QDomElement mapLayerElem = doc->createElement( "maplayer" );
          mapLayerElem.setAttribute( "embedded", 1 );
          mapLayerElem.setAttribute( "project", writePath( emIt.value().first ) );
          mapLayerElem.setAttribute( "id", ml->id() );
          projectLayersNode.appendChild( mapLayerElem );
        }
      }
    }
    li++;
  }

  qgisNode.appendChild( projectLayersNode );

  // now add the optional extra properties

  dump_( imp_->properties_ );

  QgsDebugMsg( QString( "there are %1 property scopes" ).arg( static_cast<int>( imp_->properties_.count() ) ) );

  if ( !imp_->properties_.isEmpty() ) // only worry about properties if we
    // actually have any properties
  {
    imp_->properties_.writeXML( "properties", qgisNode, *doc );
  }

  // now wrap it up and ship it to the project file
  doc->normalize();             // XXX I'm not entirely sure what this does

  //QString xml = doc->toString(4); // write to string with indentation of four characters
  // (yes, four is arbitrary)

  // const char * xmlString = xml; // debugger probe point
  // qDebug( "project file output:\n\n" + xml );

  QTextStream projectFileStream( &imp_->file );

  //projectFileStream << xml << endl;
  doc->save( projectFileStream, 4 );  // save as utf-8
  imp_->file.close();

  // check if the text stream had no error - if it does
  // the user will get a message so they can try to resolve the
  // situation e.g. by saving project to a volume with more space
  //
  if ( projectFileStream.pos() == -1  || imp_->file.error() != QFile::NoError )
  {
    setError( tr( "Unable to save to file %1. Your project "
                  "may be corrupted on disk. Try clearing some space on the volume and "
                  "check file permissions before pressing save again." )
              .arg( imp_->file.fileName() ) );
    return false;
  }

  dirty( false );               // reset to pristine state

  return true;
} // QgsProject::write



void QgsProject::clearProperties()
{
  //QgsDebugMsg("entered.");

  imp_->clear();

  dirty( true );
} // QgsProject::clearProperties()



bool
QgsProject::writeEntry( QString const &scope, const QString & key, bool value )
{
  dirty( true );

  return addKey_( scope, key, &imp_->properties_, value );
} // QgsProject::writeEntry ( ..., bool value )


bool
QgsProject::writeEntry( QString const &scope, const QString & key,
                        double value )
{
  dirty( true );

  return addKey_( scope, key, &imp_->properties_, value );
} // QgsProject::writeEntry ( ..., double value )


bool
QgsProject::writeEntry( QString const &scope, const QString & key, int value )
{
  dirty( true );

  return addKey_( scope, key, &imp_->properties_, value );
} // QgsProject::writeEntry ( ..., int value )


bool
QgsProject::writeEntry( QString const &scope, const QString & key,
                        const QString & value )
{
  dirty( true );

  return addKey_( scope, key, &imp_->properties_, value );
} // QgsProject::writeEntry ( ..., const QString & value )


bool
QgsProject::writeEntry( QString const &scope, const QString & key,
                        const QStringList & value )
{
  dirty( true );

  return addKey_( scope, key, &imp_->properties_, value );
} // QgsProject::writeEntry ( ..., const QStringList & value )




QStringList
QgsProject::readListEntry( QString const & scope,
                           const QString & key,
                           bool * ok ) const
{
  QgsProperty * property = findKey_( scope, key, imp_->properties_ );

  QVariant value;

  if ( property )
  {
    value = property->value();
  }

  bool valid = QVariant::StringList == value.type();

  if ( ok )
  {
    *ok = valid;
  }

  if ( valid )
  {
    return value.toStringList();
  }

  return QStringList();
} // QgsProject::readListEntry


QString
QgsProject::readEntry( QString const & scope,
                       const QString & key,
                       const QString & def,
                       bool * ok ) const
{
  QgsProperty * property = findKey_( scope, key, imp_->properties_ );

  QVariant value;

  if ( property )
  {
    value = property->value();
  }

  bool valid = value.canConvert( QVariant::String );

  if ( ok )
  {
    *ok = valid;
  }

  if ( valid )
  {
    return value.toString();
  }

  return QString( def );
} // QgsProject::readEntry


int
QgsProject::readNumEntry( QString const &scope, const QString & key, int def,
                          bool * ok ) const
{
  QgsProperty * property = findKey_( scope, key, imp_->properties_ );

  QVariant value;

  if ( property )
  {
    value = property->value();
  }

  bool valid = value.canConvert( QVariant::String );

  if ( ok )
  {
    *ok = valid;
  }

  if ( valid )
  {
    return value.toInt();
  }

  return def;
} // QgsProject::readNumEntry


double
QgsProject::readDoubleEntry( QString const &scope, const QString & key,
                             double def,
                             bool * ok ) const
{
  QgsProperty * property = findKey_( scope, key, imp_->properties_ );

  QVariant value;

  if ( property )
  {
    value = property->value();
  }

  bool valid = value.canConvert( QVariant::Double );

  if ( ok )
  {
    *ok = valid;
  }

  if ( valid )
  {
    return value.toDouble();
  }

  return def;
} // QgsProject::readDoubleEntry


bool
QgsProject::readBoolEntry( QString const &scope, const QString & key, bool def,
                           bool * ok ) const
{
  QgsProperty * property = findKey_( scope, key, imp_->properties_ );

  QVariant value;

  if ( property )
  {
    value = property->value();
  }

  bool valid = value.canConvert( QVariant::Bool );

  if ( ok )
  {
    *ok = valid;
  }

  if ( valid )
  {
    return value.toBool();
  }

  return def;
} // QgsProject::readBoolEntry


bool QgsProject::removeEntry( QString const &scope, const QString & key )
{
  removeKey_( scope, key, imp_->properties_ );

  dirty( true );

  return ! findKey_( scope, key, imp_->properties_ );
} // QgsProject::removeEntry



QStringList QgsProject::entryList( QString const &scope, QString const &key ) const
{
  QgsProperty * foundProperty = findKey_( scope, key, imp_->properties_ );

  QStringList entries;

  if ( foundProperty )
  {
    QgsPropertyKey * propertyKey = dynamic_cast<QgsPropertyKey*>( foundProperty );

    if ( propertyKey )
      { propertyKey->entryList( entries ); }
  }

  return entries;
} // QgsProject::entryList


QStringList
QgsProject::subkeyList( QString const &scope, QString const &key ) const
{
  QgsProperty * foundProperty = findKey_( scope, key, imp_->properties_ );

  QStringList entries;

  if ( foundProperty )
  {
    QgsPropertyKey * propertyKey = dynamic_cast<QgsPropertyKey*>( foundProperty );

    if ( propertyKey )
      { propertyKey->subkeyList( entries ); }
  }

  return entries;

} // QgsProject::subkeyList



void QgsProject::dumpProperties() const
{
  dump_( imp_->properties_ );
} // QgsProject::dumpProperties


// return the absolute path from a filename read from project file
QString QgsProject::readPath( QString src ) const
{
  if ( readBoolEntry( "Paths", "/Absolute", false ) )
  {
    return src;
  }

  // relative path should always start with ./ or ../
  if ( !src.startsWith( "./" ) && !src.startsWith( "../" ) )
  {
#if defined(Q_OS_WIN)
    if ( src.startsWith( "\\\\" ) ||
         src.startsWith( "//" ) ||
         ( src[0].isLetter() && src[1] == ':' ) )
    {
      // UNC or absolute path
      return src;
    }
#else
    if ( src[0] == '/' )
    {
      // absolute path
      return src;
    }
#endif

    // so this one isn't absolute, but also doesn't start // with ./ or ../.
    // That means that it was saved with an earlier version of "relative path support",
    // where the source file had to exist and only the project directory was stripped
    // from the filename.
    QFileInfo pfi( fileName() );
    if ( !pfi.exists() )
      return src;

    QFileInfo fi( pfi.canonicalPath() + "/" + src );

    if ( !fi.exists() )
    {
      return src;
    }
    else
    {
      return fi.canonicalFilePath();
    }
  }

  QString srcPath = src;
  QString projPath = fileName();

  if ( projPath.isEmpty() )
  {
    return src;
  }

#if defined(Q_OS_WIN)
  srcPath.replace( "\\", "/" );
  projPath.replace( "\\", "/" );

  bool uncPath = projPath.startsWith( "//" );
#endif

  QStringList srcElems = srcPath.split( "/", QString::SkipEmptyParts );
  QStringList projElems = projPath.split( "/", QString::SkipEmptyParts );

#if defined(Q_OS_WIN)
  if ( uncPath )
  {
    projElems.insert( 0, "" );
    projElems.insert( 0, "" );
  }
#endif

  // remove project file element
  projElems.removeLast();

  // append source path elements
  projElems << srcElems;
  projElems.removeAll( "." );

  // resolve ..
  int pos;
  while (( pos = projElems.indexOf( ".." ) ) > 0 )
  {
    // remove preceding element and ..
    projElems.removeAt( pos - 1 );
    projElems.removeAt( pos - 1 );
  }

#if !defined(Q_OS_WIN)
  // make path absolute
  projElems.prepend( "" );
#endif

  return projElems.join( "/" );
}

// return the absolute or relative path to write it to the project file
QString QgsProject::writePath( QString src ) const
{
  if ( readBoolEntry( "Paths", "/Absolute", false ) || src.isEmpty() )
  {
    return src;
  }

  QString srcPath = src;
  QString projPath = fileName();

  if ( projPath.isEmpty() )
  {
    return src;
  }

#if defined( Q_OS_WIN )
  const Qt::CaseSensitivity cs = Qt::CaseInsensitive;

  srcPath.replace( "\\", "/" );

  if ( srcPath.startsWith( "//" ) )
  {
    // keep UNC prefix
    srcPath = "\\\\" + srcPath.mid( 2 );
  }

  projPath.replace( "\\", "/" );
  if ( projPath.startsWith( "//" ) )
  {
    // keep UNC prefix
    projPath = "\\\\" + projPath.mid( 2 );
  }
#else
  const Qt::CaseSensitivity cs = Qt::CaseSensitive;
#endif

  QStringList projElems = projPath.split( "/", QString::SkipEmptyParts );
  QStringList srcElems = srcPath.split( "/", QString::SkipEmptyParts );

  // remove project file element
  projElems.removeLast();

  projElems.removeAll( "." );
  srcElems.removeAll( "." );

  // remove common part
  int n = 0;
  while ( srcElems.size() > 0 &&
          projElems.size() > 0 &&
          srcElems[0].compare( projElems[0], cs ) == 0 )
  {
    srcElems.removeFirst();
    projElems.removeFirst();
    n++;
  }

  if ( n == 0 )
  {
    // no common parts; might not even by a file
    return src;
  }

  if ( projElems.size() > 0 )
  {
    // go up to the common directory
    for ( int i = 0; i < projElems.size(); i++ )
    {
      srcElems.insert( 0, ".." );
    }
  }
  else
  {
    // let it start with . nevertheless,
    // so relative path always start with either ./ or ../
    srcElems.insert( 0, "." );
  }

  return srcElems.join( "/" );
}

void QgsProject::setError( QString errorMessage )
{
  mErrorMessage = errorMessage;
}

QString QgsProject::error() const
{
  return mErrorMessage;
}

void QgsProject::clearError()
{
  setError( QString() );
}

void QgsProject::setBadLayerHandler( QgsProjectBadLayerHandler* handler )
{
  delete mBadLayerHandler;
  mBadLayerHandler = handler;
}

QString QgsProject::layerIsEmbedded( const QString& id ) const
{
  QHash< QString, QPair< QString, bool > >::const_iterator it = mEmbeddedLayers.find( id );
  if ( it == mEmbeddedLayers.constEnd() )
  {
    return QString();
  }
  return it.value().first;
};

bool QgsProject::createEmbeddedLayer( const QString& layerId, const QString& projectFilePath, QList<QDomNode>& brokenNodes,
                                      QList< QPair< QgsVectorLayer*, QDomElement > >& vectorLayerList, bool saveFlag )
{
  QFile projectFile( projectFilePath );
  if ( !projectFile.open( QIODevice::ReadOnly ) )
  {
    return false;
  }

  QDomDocument projectDocument;
  if ( !projectDocument.setContent( &projectFile ) )
  {
    return false;
  }

  //does project store pathes absolute or relative?
  bool useAbsolutePathes = true;
  QDomElement propertiesElem = projectDocument.documentElement().firstChildElement( "properties" );
  if ( !propertiesElem.isNull() )
  {
    QDomElement absElem = propertiesElem.firstChildElement( "Paths" ).firstChildElement( "Absolute" );
    if ( !absElem.isNull() )
    {
      useAbsolutePathes = absElem.text().compare( "true", Qt::CaseInsensitive ) == 0;
    }
  }

  QDomElement projectLayersElem = projectDocument.documentElement().firstChildElement( "projectlayers" );
  if ( projectLayersElem.isNull() )
  {
    return false;
  }

  QDomNodeList mapLayerNodes = projectLayersElem.elementsByTagName( "maplayer" );
  for ( int i = 0; i < mapLayerNodes.size(); ++i )
  {
    //get layer id
    QDomElement mapLayerElem = mapLayerNodes.at( i ).toElement();
    QString id = mapLayerElem.firstChildElement( "id" ).text();
    if ( id == layerId )
    {
      //layer can be embedded only once
      if ( mapLayerElem.attribute( "embedded" ) == "1" )
      {
        return false;
      }

      mEmbeddedLayers.insert( layerId, qMakePair( projectFilePath, saveFlag ) );

      //change datasource path from relative to absolute if necessary
      if ( !useAbsolutePathes )
      {
        QDomElement dsElem = mapLayerElem.firstChildElement( "datasource" );
        QString debug( QFileInfo( projectFilePath ).absolutePath() + "/" + dsElem.text() );
        QFileInfo absoluteDs( QFileInfo( projectFilePath ).absolutePath() + "/" + dsElem.text() );
        if ( absoluteDs.exists() )
        {
          dsElem.removeChild( dsElem.childNodes().at( 0 ) );
          dsElem.appendChild( projectDocument.createTextNode( absoluteDs.absoluteFilePath() ) );
        }
      }

      if ( addLayer( mapLayerElem, brokenNodes, vectorLayerList ) )
      {
        return true;
      }
      else
      {
        mEmbeddedLayers.remove( layerId );
        return false;
      }
    }
  }

  return false;
}

void QgsProjectBadLayerDefaultHandler::handleBadLayers( QList<QDomNode> /*layers*/, QDomDocument /*projectDom*/ )
{
  // just ignore any bad layers
}

---