QWidget *QgsAuthMethodRegistry::editWidget( const QString &authMethodKey, QWidget *parent )
{
  editFactoryFunction_t * editFactory =
    ( editFactoryFunction_t * ) cast_to_fptr( function( authMethodKey, "editWidget" ) );

  if ( !editFactory )
    return 0;

  return editFactory( parent );
}

QWidget* QgsProviderRegistry::selectWidget( const QString & providerKey,
    QWidget * parent, Qt::WFlags fl )
{
  selectFactoryFunction_t * selectFactory =
    ( selectFactoryFunction_t * ) cast_to_fptr( function( providerKey, "selectWidget" ) );

  if ( !selectFactory )
    return 0;

  return selectFactory( parent, fl );
}

QWidget *QgsProviderRegistry::createSelectionWidget( const QString &providerKey,
    QWidget *parent, Qt::WindowFlags fl, QgsProviderRegistry::WidgetMode widgetMode )
{
  selectFactoryFunction_t *selectFactory =
    reinterpret_cast< selectFactoryFunction_t * >( cast_to_fptr( function( providerKey, "selectWidget" ) ) );

  if ( !selectFactory )
    return nullptr;

  return selectFactory( parent, fl, widgetMode );
}

/** Copied from QgsVectorLayer::setDataProvider
 *  TODO: Make it work in the generic environment
 *
 *  TODO: Is this class really the best place to put a data provider loader?
 *        It seems more sensible to provide the code in one place rather than
 *        in qgsrasterlayer, qgsvectorlayer, serversourceselect, etc.
 */
QgsDataProvider *QgsProviderRegistry::provider( QString const & providerKey, QString const & dataSource )
{
  // XXX should I check for and possibly delete any pre-existing providers?
  // XXX How often will that scenario occur?

  // load the plugin
  QString lib = library( providerKey );

#ifdef TESTPROVIDERLIB
  const char *cLib = lib.toUtf8();

  // test code to help debug provider loading problems
  //  void *handle = dlopen(cLib, RTLD_LAZY);
  void *handle = dlopen( cOgrLib, RTLD_LAZY | RTLD_GLOBAL );
  if ( !handle )
  {
    QgsLogger::warning( "Error in dlopen" );
  }
  else
  {
    QgsDebugMsg( "dlopen suceeded" );
    dlclose( handle );
  }

#endif
  // load the data provider
  QLibrary myLib( lib );

  QgsDebugMsg( "Library name is " + myLib.fileName() );
  if ( !myLib.load() )
  {
    QgsMessageLog::logMessage( QObject::tr( "Failed to load %1: %2" ).arg( lib ).arg( myLib.errorString() ) );
    return 0;
  }

  classFactoryFunction_t *classFactory = ( classFactoryFunction_t * ) cast_to_fptr( myLib.resolve( "classFactory" ) );
  if ( !classFactory )
  {
    QgsDebugMsg( QString( "Failed to load %1: no classFactory method" ).arg( lib ) );
    return 0;
  }

  QgsDataProvider *dataProvider = classFactory( &dataSource );
  if ( !dataProvider )
  {
    QgsMessageLog::logMessage( QObject::tr( "Unable to instantiate the data provider plugin %1" ).arg( lib ) );
    myLib.unload();
    return 0;
  }

  QgsDebugMsg( QString( "Instantiated the data provider plugin: %1" ).arg( dataProvider->name() ) );
  return dataProvider;
} // QgsProviderRegistry::setDataProvider

void QgsProviderRegistry::registerGuis( QWidget *parent )
{
  typedef void registerGui_function( QWidget * parent );

  foreach ( const QString &provider, providerList() )
  {
    registerGui_function *registerGui = ( registerGui_function * ) cast_to_fptr( function( provider, "registerGui" ) );

    if ( !registerGui )
      continue;

    registerGui( parent );
  }

void QgsProviderRegistry::registerGuis( QWidget *parent )
{
  typedef void registerGui_function( QWidget * parent );

  Q_FOREACH ( const QString &provider, providerList() )
  {
    registerGui_function *registerGui = reinterpret_cast< registerGui_function * >( cast_to_fptr( function( provider, "registerGui" ) ) );

    if ( !registerGui )
      continue;

    registerGui( parent );
  }

QgsAuthMethod *QgsAuthMethodRegistry::authMethod( const QString &authMethodKey )
{
  // load the plugin
  QString lib = library( authMethodKey );

#ifdef TESTAUTHMETHODLIB
  const char *cLib = lib.toUtf8();

  // test code to help debug auth method plugin loading problems
  //  void *handle = dlopen(cLib, RTLD_LAZY);
  void *handle = dlopen( cOgrLib, RTLD_LAZY | RTLD_GLOBAL );
  if ( !handle )
  {
    QgsLogger::warning( "Error in dlopen" );
  }
  else
  {
    QgsDebugMsg( "dlopen suceeded" );
    dlclose( handle );
  }

#endif
  // load the auth method
  QLibrary myLib( lib );

  QgsDebugMsg( "Auth method library name is " + myLib.fileName() );
  if ( !myLib.load() )
  {
    QgsMessageLog::logMessage( QObject::tr( "Failed to load %1: %2" ).arg( lib, myLib.errorString() ) );
    return 0;
  }

  classFactoryFunction_t *classFactory = ( classFactoryFunction_t * ) cast_to_fptr( myLib.resolve( "classFactory" ) );
  if ( !classFactory )
  {
    QgsDebugMsg( QString( "Failed to load %1: no classFactory method" ).arg( lib ) );
    return 0;
  }

  QgsAuthMethod *authMethod = classFactory();
  if ( !authMethod )
  {
    QgsMessageLog::logMessage( QObject::tr( "Unable to instantiate the auth method plugin %1" ).arg( lib ) );
    myLib.unload();
    return 0;
  }

  QgsDebugMsg( QString( "Instantiated the auth method plugin: %1" ).arg( authMethod->key() ) );
  return authMethod;
}

QgsTransaction* QgsTransaction::create( const QString& connString, const QString& providerKey )
{
  std::unique_ptr< QLibrary > lib( QgsProviderRegistry::instance()->providerLibrary( providerKey ) );
  if ( !lib )
    return nullptr;

  createTransaction_t* createTransaction = reinterpret_cast< createTransaction_t* >( cast_to_fptr( lib->resolve( "createTransaction" ) ) );
  if ( !createTransaction )
    return nullptr;

  QgsTransaction* ts = createTransaction( connString );

  return ts;
}

int GRASS_LIB_EXPORT G_parser( int argc, char **argv )
{
    QgsDebugMsg( "Entered" );
    G_parser_type* fn = ( G_parser_type* ) cast_to_fptr( QgsGrassGisLib::instance()->resolve( "G_parser" ) );
    int ret = fn( argc, argv );

    if ( ret == 0 ) // parsed OK
    {
        // It would be useful to determine the region from input raster layers if
        // no one is given by environment variable but there seems to be no way to
        // get access to module options. Everything is in static variables in
        // parser.c and there are no access functions to them.
    }
    return ret;
}

int QgsProviderRegistry::providerCapabilities( const QString &providerKey ) const
{
  std::unique_ptr< QLibrary > library( createProviderLibrary( providerKey ) );
  if ( !library )
  {
    return QgsDataProvider::NoDataCapabilities;
  }

  dataCapabilities_t *dataCapabilities = reinterpret_cast< dataCapabilities_t *>( cast_to_fptr( library->resolve( "dataCapabilities" ) ) );
  if ( !dataCapabilities )
  {
    return QgsDataProvider::NoDataCapabilities;
  }

  return dataCapabilities();
}

int QgsProviderRegistry::providerCapabilities( const QString &providerKey ) const
{
    QLibrary *library = providerLibrary( providerKey );
    if ( !library )
    {
        return QgsDataProvider::NoDataCapabilities;
    }

    dataCapabilities_t * dataCapabilities = ( dataCapabilities_t * ) cast_to_fptr( library->resolve( "dataCapabilities" ) );
    if ( !dataCapabilities )
    {
        return QgsDataProvider::NoDataCapabilities;
    }

    return dataCapabilities();
}

QgsProviderRegistry::~QgsProviderRegistry()
{
  Providers::const_iterator it = mProviders.begin();

  while ( it != mProviders.end() )
  {
    QString lib = it->second->library();
    QLibrary myLib( lib );
    if ( myLib.isLoaded() )
    {
      cleanupProviderFunction_t* cleanupFunc = ( cleanupProviderFunction_t* ) cast_to_fptr( myLib.resolve( "cleanupProvider" ) );
      if ( cleanupFunc )
        cleanupFunc();
    }
    ++it;
  }
}

QgsRasterDataProvider *QgsRasterDataProvider::create( const QString &providerKey,
    const QString &uri,
    const QString &format, int nBands,
    Qgis::DataType type,
    int width, int height, double *geoTransform,
    const QgsCoordinateReferenceSystem &crs,
    const QStringList &createOptions )
{
  createFunction_t *createFn = reinterpret_cast< createFunction_t * >( cast_to_fptr( QgsProviderRegistry::instance()->function( providerKey, "create" ) ) );
  if ( !createFn )
  {
    QgsDebugMsg( "Cannot resolve 'create' function in " + providerKey + " provider" );
    // TODO: it would be good to return invalid QgsRasterDataProvider
    // with QgsError set, but QgsRasterDataProvider has pure virtual methods
    return nullptr;
  }
  return createFn( uri, format, nBands, type, width, height, geoTransform, crs, createOptions );
}

QgsAuthMethodRegistry::~QgsAuthMethodRegistry()
{
  AuthMethods::const_iterator it = mAuthMethods.begin();

  while ( it != mAuthMethods.end() )
  {
    QgsDebugMsg( QString( "cleanup: %1" ).arg( it->first ) );
    QString lib = it->second->library();
    QLibrary myLib( lib );
    if ( myLib.isLoaded() )
    {
      cleanupAuthMethod_t* cleanupFunc = ( cleanupAuthMethod_t* ) cast_to_fptr( myLib.resolve( "cleanupAuthMethod" ) );
      if ( cleanupFunc )
        cleanupFunc();
    }
    // clear cached QgsAuthMethodMetadata *
    delete it->second;
    ++it;
  }
}

QgsTransaction* QgsTransaction::create( const QString& connString, const QString& providerKey )
{

  QLibrary* lib = QgsProviderRegistry::instance()->providerLibrary( providerKey );
  if ( !lib )
  {
    return 0;
  }

  createTransaction_t* createTransaction = ( createTransaction_t* ) cast_to_fptr( lib->resolve( "createTransaction" ) );
  if ( !createTransaction )
  {
    return 0;
  }

  QgsTransaction* ts = createTransaction( connString );

  delete lib;

  return ts;
}

QgsProviderRegistry::~QgsProviderRegistry()
{
    QgsMapLayerRegistry::instance()->removeAllMapLayers();

    Providers::const_iterator it = mProviders.begin();

    while ( it != mProviders.end() )
    {
        QgsDebugMsg( QString( "cleanup:%1" ).arg( it->first ) );
        QString lib = it->second->library();
        QLibrary myLib( lib );
        if ( myLib.isLoaded() )
        {
            cleanupProviderFunction_t* cleanupFunc = ( cleanupProviderFunction_t* ) cast_to_fptr( myLib.resolve( "cleanupProvider" ) );
            if ( cleanupFunc )
                cleanupFunc();
        }
        delete it->second;
        ++it;
    }
}

int GRASS_LIB_EXPORT G_lookup_key_value_from_file( const char *file, const char *key, char value[], int n )
{
    G_lookup_key_value_from_file_type *fn = ( G_lookup_key_value_from_file_type* ) cast_to_fptr( QgsGrassGisLib::instance()->resolve( "G_lookup_key_value_from_file" ) );
    return fn( file, key, value, n );
}

QgsProviderRegistry::QgsProviderRegistry( QString pluginPath )
{
  // At startup, examine the libs in the qgis/lib dir and store those that
  // are a provider shared lib
  // check all libs in the current plugin directory and get name and descriptions
  //TODO figure out how to register and identify data source plugin for a specific
  //TODO layer type
#if 0
  char **argv = qApp->argv();
  QString appDir = argv[0];
  int bin = appDir.findRev( "/bin", -1, false );
  QString baseDir = appDir.left( bin );
  QString mLibraryDirectory = baseDir + "/lib";
#endif
  mLibraryDirectory = pluginPath;
  mLibraryDirectory.setSorting( QDir::Name | QDir::IgnoreCase );
  mLibraryDirectory.setFilter( QDir::Files | QDir::NoSymLinks );

#if defined(WIN32) || defined(__CYGWIN__)
  mLibraryDirectory.setNameFilters( QStringList( "*.dll" ) );
#elif ANDROID
  mLibraryDirectory.setNameFilters( QStringList( "*provider.so" ) );
#else
  mLibraryDirectory.setNameFilters( QStringList( "*.so" ) );
#endif

  QgsDebugMsg( QString( "Checking %1 for provider plugins" ).arg( mLibraryDirectory.path() ) );

  if ( mLibraryDirectory.count() == 0 )
  {
    QString msg = QObject::tr( "No QGIS data provider plugins found in:\n%1\n" ).arg( mLibraryDirectory.path() );
    msg += QObject::tr( "No vector layers can be loaded. Check your QGIS installation" );

    QgsMessageOutput* output = QgsMessageOutput::createMessageOutput();
    output->setTitle( QObject::tr( "No Data Providers" ) );
    output->setMessage( msg, QgsMessageOutput::MessageText );
    output->showMessage();
    return;
  }

  QListIterator<QFileInfo> it( mLibraryDirectory.entryInfoList() );
  while ( it.hasNext() )
  {
    QFileInfo fi( it.next() );

    QLibrary myLib( fi.filePath() );
    if ( !myLib.load() )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (lib not loadable): %2" ).arg( myLib.fileName() ).arg( myLib.errorString() ) );
      continue;
    }

    //MH: Added a further test to detect non-provider plugins linked to provider plugins.
    //Only pure provider plugins have 'type' not defined
    isprovider_t *hasType = ( isprovider_t * ) cast_to_fptr( myLib.resolve( "type" ) );
    if ( hasType )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (has type method)" ).arg( myLib.fileName() ) );
      continue;
    }

    // get the description and the key for the provider plugin
    isprovider_t *isProvider = ( isprovider_t * ) cast_to_fptr( myLib.resolve( "isProvider" ) );
    if ( !isProvider )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (no isProvider method)" ).arg( myLib.fileName() ) );
      continue;
    }

    // check to see if this is a provider plugin
    if ( !isProvider() )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (not a provider)" ).arg( myLib.fileName() ) );
      continue;
    }

    // looks like a provider. get the key and description
    description_t *pDesc = ( description_t * ) cast_to_fptr( myLib.resolve( "description" ) );
    if ( !pDesc )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (no description method)" ).arg( myLib.fileName() ) );
      continue;
    }

    providerkey_t *pKey = ( providerkey_t * ) cast_to_fptr( myLib.resolve( "providerKey" ) );
    if ( !pKey )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (no providerKey method)" ).arg( myLib.fileName() ) );
      continue;
    }

    // add this provider to the provider map
    mProviders[pKey()] = new QgsProviderMetadata( pKey(), pDesc(), myLib.fileName() );

    // load database drivers
    databaseDrivers_t *pDatabaseDrivers = ( databaseDrivers_t * ) cast_to_fptr( myLib.resolve( "databaseDrivers" ) );
    if ( pDatabaseDrivers )
    {
      mDatabaseDrivers = pDatabaseDrivers();
    }
//.........这里部分代码省略.........

void QgsProviderRegistry::init()
{
  // add standard providers
  mProviders[ QgsMemoryProvider::providerKey() ] = new QgsProviderMetadata( QgsMemoryProvider::providerKey(), QgsMemoryProvider::providerDescription(), &QgsMemoryProvider::createProvider );

  mLibraryDirectory.setSorting( QDir::Name | QDir::IgnoreCase );
  mLibraryDirectory.setFilter( QDir::Files | QDir::NoSymLinks );

#if defined(Q_OS_WIN) || defined(__CYGWIN__)
  mLibraryDirectory.setNameFilters( QStringList( "*.dll" ) );
#elif defined(ANDROID)
  mLibraryDirectory.setNameFilters( QStringList( "*provider.so" ) );
#else
  mLibraryDirectory.setNameFilters( QStringList( QStringLiteral( "*.so" ) ) );
#endif

  QgsDebugMsg( QString( "Checking %1 for provider plugins" ).arg( mLibraryDirectory.path() ) );

  if ( mLibraryDirectory.count() == 0 )
  {
    QString msg = QObject::tr( "No QGIS data provider plugins found in:\n%1\n" ).arg( mLibraryDirectory.path() );
    msg += QObject::tr( "No vector layers can be loaded. Check your QGIS installation" );

    QgsMessageOutput *output = QgsMessageOutput::createMessageOutput();
    output->setTitle( QObject::tr( "No Data Providers" ) );
    output->setMessage( msg, QgsMessageOutput::MessageText );
    output->showMessage();
    return;
  }

  // provider file regex pattern, only files matching the pattern are loaded if the variable is defined
  QString filePattern = getenv( "QGIS_PROVIDER_FILE" );
  QRegExp fileRegexp;
  if ( !filePattern.isEmpty() )
  {
    fileRegexp.setPattern( filePattern );
  }

  Q_FOREACH ( const QFileInfo &fi, mLibraryDirectory.entryInfoList() )
  {
    if ( !fileRegexp.isEmpty() )
    {
      if ( fileRegexp.indexIn( fi.fileName() ) == -1 )
      {
        QgsDebugMsg( "provider " + fi.fileName() + " skipped because doesn't match pattern " + filePattern );
        continue;
      }
    }

    QLibrary myLib( fi.filePath() );
    if ( !myLib.load() )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (lib not loadable): %2" ).arg( myLib.fileName(), myLib.errorString() ) );
      continue;
    }

    //MH: Added a further test to detect non-provider plugins linked to provider plugins.
    //Only pure provider plugins have 'type' not defined
    isprovider_t *hasType = reinterpret_cast< isprovider_t * >( cast_to_fptr( myLib.resolve( "type" ) ) );
    if ( hasType )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (has type method)" ).arg( myLib.fileName() ) );
      continue;
    }

    // get the description and the key for the provider plugin
    isprovider_t *isProvider = reinterpret_cast< isprovider_t * >( cast_to_fptr( myLib.resolve( "isProvider" ) ) );
    if ( !isProvider )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (no isProvider method)" ).arg( myLib.fileName() ) );
      continue;
    }

    // check to see if this is a provider plugin
    if ( !isProvider() )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (not a provider)" ).arg( myLib.fileName() ) );
      continue;
    }

    // looks like a provider. get the key and description
    description_t *pDesc = reinterpret_cast< description_t * >( cast_to_fptr( myLib.resolve( "description" ) ) );
    if ( !pDesc )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (no description method)" ).arg( myLib.fileName() ) );
      continue;
    }

    providerkey_t *pKey = reinterpret_cast< providerkey_t * >( cast_to_fptr( myLib.resolve( "providerKey" ) ) );
    if ( !pKey )
    {
      QgsDebugMsg( QString( "Checking %1: ...invalid (no providerKey method)" ).arg( myLib.fileName() ) );
      continue;
    }

    // add this provider to the provider map
    mProviders[pKey()] = new QgsProviderMetadata( pKey(), pDesc(), myLib.fileName() );

    // load database drivers
    databaseDrivers_t *pDatabaseDrivers = reinterpret_cast< databaseDrivers_t * >( cast_to_fptr( myLib.resolve( "databaseDrivers" ) ) );
//.........这里部分代码省略.........

bool QgsGeometryCheckerResultTab::exportErrorsDo( const QString &file )
{
  QList< QPair<QString, QString> > attributes;
  attributes.append( qMakePair( QStringLiteral( "Layer" ), QStringLiteral( "String;30;" ) ) );
  attributes.append( qMakePair( QStringLiteral( "FeatureID" ), QStringLiteral( "String;10;" ) ) );
  attributes.append( qMakePair( QStringLiteral( "ErrorDesc" ), QStringLiteral( "String;80;" ) ) );

  QFileInfo fi( file );
  QString ext = fi.suffix();
  QString driver = QgsVectorFileWriter::driverForExtension( ext );

  QLibrary ogrLib( QgsProviderRegistry::instance()->library( QStringLiteral( "ogr" ) ) );
  if ( !ogrLib.load() )
  {
    return false;
  }
  typedef bool ( *createEmptyDataSourceProc )( const QString &, const QString &, const QString &, QgsWkbTypes::Type, const QList< QPair<QString, QString> > &, const QgsCoordinateReferenceSystem & );
  createEmptyDataSourceProc createEmptyDataSource = ( createEmptyDataSourceProc ) cast_to_fptr( ogrLib.resolve( "createEmptyDataSource" ) );
  if ( !createEmptyDataSource )
  {
    return false;
  }
  if ( !createEmptyDataSource( file, driver, "UTF-8", QgsWkbTypes::Point, attributes, QgsProject::instance()->crs() ) )
  {
    return false;
  }
  QgsVectorLayer *layer = new QgsVectorLayer( file, QFileInfo( file ).baseName(), QStringLiteral( "ogr" ) );
  if ( !layer->isValid() )
  {
    delete layer;
    return false;
  }

  int fieldLayer = layer->fields().lookupField( QStringLiteral( "Layer" ) );
  int fieldFeatureId = layer->fields().lookupField( QStringLiteral( "FeatureID" ) );
  int fieldErrDesc = layer->fields().lookupField( QStringLiteral( "ErrorDesc" ) );
  for ( int row = 0, nRows = ui.tableWidgetErrors->rowCount(); row < nRows; ++row )
  {
    QgsGeometryCheckError *error = ui.tableWidgetErrors->item( row, 0 )->data( Qt::UserRole ).value<QgsGeometryCheckError *>();
    QgsVectorLayer *srcLayer = mChecker->featurePools()[error->layerId()]->layer();
    QgsFeature f( layer->fields() );
    f.setAttribute( fieldLayer, srcLayer->name() );
    f.setAttribute( fieldFeatureId, error->featureId() );
    f.setAttribute( fieldErrDesc, error->description() );
    QgsGeometry geom( new QgsPoint( error->location() ) );
    f.setGeometry( geom );
    layer->dataProvider()->addFeatures( QgsFeatureList() << f );
  }

  // Remove existing layer with same uri
  QStringList toRemove;
  for ( QgsMapLayer *maplayer : QgsProject::instance()->mapLayers() )
  {
    if ( dynamic_cast<QgsVectorLayer *>( maplayer ) &&
         static_cast<QgsVectorLayer *>( maplayer )->dataProvider()->dataSourceUri() == layer->dataProvider()->dataSourceUri() )
    {
      toRemove.append( maplayer->id() );
    }
  }
  if ( !toRemove.isEmpty() )
  {
    QgsProject::instance()->removeMapLayers( toRemove );
  }

  QgsProject::instance()->addMapLayers( QList<QgsMapLayer *>() << layer );
  return true;
}