qgswfsprovider.h

一个非常好的GIS开源新版本

/***************************************************************************
                              qgswfsprovider.h    
                              -------------------
  begin                : July 25, 2006
  copyright            : (C) 2006 by Marco Hugentobler
  email                : marco dot hugentobler at karto dot baug dot ethz dot ch
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef QGSWFSPROVIDER_H
#define QGSWFSPROVIDER_H

#include <QDomElement>
#include "qgis.h"
#include "qgsrect.h"
#include "qgsspatialrefsys.h"
#include "qgsvectordataprovider.h"
#include <geos/version.h>
#if GEOS_VERSION_MAJOR < 3 
#include <geos/geom.h>
#include <geos/indexStrtree.h>
#define GEOS_GEOM geos
#define GEOS_INDEX_STRTREE geos 
#else 
#include <geos/geom/Envelope.h>
#include <geos/index/strtree/STRtree.h>
#define GEOS_GEOM geos::geom
#define GEOS_INDEX_STRTREE geos::index::strtree 
#endif 

class QgsRect;

/**A provider reading features from a WFS server*/
class QgsWFSProvider: public QgsVectorDataProvider
{
  Q_OBJECT
 public:

  enum REQUEST_ENCODING
    {
      GET,
      POST,
      SOAP,/*Note that this goes also through HTTP POST but additionally uses soap envelope and friends*/
      FILE  //reads from a file on disk
    };

  QgsWFSProvider(const QString& uri);
  ~QgsWFSProvider();
  
  /* Inherited from QgsVectorDataProvider */

  /** Select features based on a bounding rectangle. Features can be retrieved with calls to getNextFeature.
   *  @param fetchAttributes list of attributes which should be fetched
   *  @param rect spatial filter
   *  @param fetchGeometry true if the feature geometry should be fetched
   *  @param useIntersect true if an accurate intersection test should be used,
   *                     false if a test based on bounding box is sufficient
   */
  virtual void select(QgsAttributeList fetchAttributes = QgsAttributeList(),
                      QgsRect rect = QgsRect(),
                      bool fetchGeometry = true,
                      bool useIntersect = false);

  /**
   * Get the next feature resulting from a select operation.
   * @param feature feature which will receive data from the provider
   * @return true when there was a feature to fetch, false when end was hit
   */
  virtual bool getNextFeature(QgsFeature& feature);
  
  QGis::WKBTYPE geometryType() const;
  long featureCount() const;
  uint fieldCount() const;
  const QgsFieldMap & fields() const;
  void reset();
  
  virtual QgsSpatialRefSys getSRS();
  
  /* Inherited from QgsDataProvider */
  
  QgsRect extent();
  bool isValid();
  QString name() const;
  QString description() const;
  
  /* new functions */

  /**Sets the encoding type in which the provider makes requests and interprets
   results. Posibilities are GET, POST, SOAP*/
  void setEncoding(QgsWFSProvider::REQUEST_ENCODING e) {mEncoding = e;}

  /**Makes a GetFeatures, receives the features from the wfs server (as GML), converts them to QgsFeature and \
     stores them in a vector*/
  int getFeature(const QString& uri);


 signals:
  void dataReadProgressMessage(QString message);

  private slots:
  /**Receives the progress signals from QgsWFSData::dataReadProgress, generates a string \
   and emits the dataReadProgressMessage signal*/
  void handleWFSProgressMessage(int done, int total);
  

 protected:
  QgsFieldMap mFields;
  /**The encoding used for request/response. Can be GET, POST or SOAP*/
  REQUEST_ENCODING mEncoding;
  /**Bounding box for the layer*/
  QgsRect mExtent;
  /**Spatial filter for the layer*/
  QgsRect mSpatialFilter;
  /**Flag if precise intersection test is needed. Otherwise, every feature is returned (even if a filter is set)*/
  bool mUseIntersect;
  /**A spatial index for fast access to a feature subset*/
  GEOS_INDEX_STRTREE::STRtree mSpatialIndex;
  /**Stores all the inserted rectangles and features. This is used to clean up the memory in the destructor*/
  std::list< std::pair<GEOS_GEOM::Envelope*, QgsFeature*> > mEnvelopesAndFeatures;
  /**Vector where the QgsFeature* of a query are inserted*/
  std::vector<void*>* mSelectedFeatures;
  /**Iterator on the feature vector for use in reset(), getNextFeature(), etc...*/
  std::vector<void*>::iterator mFeatureIterator;
  /**Geometry type of the features in this layer*/
  mutable QGis::WKBTYPE mWKBType;
  /**Source SRS*/
  QgsSpatialRefSys mSourceSRS;
  int mFeatureCount;
  /**Flag if provider is valid*/
  bool mValid;

  
  /**Collects information about the field types. Is called internally from QgsWFSProvider::getFeature. The method delegates the work to request specific ones and gives back the name of the geometry attribute and the thematic attributes with their types*/
  int describeFeatureType(const QString& uri, QString& geometryAttribute, QgsFieldMap& fields);

  //encoding specific methods of getFeature
  int getFeatureGET(const QString& uri, const QString& geometryAttribute);
  int getFeaturePOST(const QString& uri, const QString& geometryAttribute);
  int getFeatureSOAP(const QString& uri, const QString& geometryAttribute);
  int getFeatureFILE(const QString& uri, const QString& geometryAttribute);
  //encoding specific methods of describeFeatureType
  int describeFeatureTypeGET(const QString& uri, QString& geometryAttribute, QgsFieldMap& fields);
  int describeFeatureTypePOST(const QString& uri, QString& geometryAttribute, QgsFieldMap& fields);
  int describeFeatureTypeSOAP(const QString& uri, QString& geometryAttribute, QgsFieldMap& fields);
  int describeFeatureTypeFile(const QString& uri, QString& geometryAttribute, QgsFieldMap& fields);

  /**Reads the name of the geometry attribute, the thematic attributes and their types from a dom document. Returns 0 in case of success*/
  int readAttributesFromSchema(QDomDocument& schemaDoc, QString& geometryAttribute, QgsFieldMap& fields) const;
  /**This method tries to guess the geometry attribute and the other attribute names from the .gml file if no schema is present. Returns 0 in case of success*/
  int guessAttributesFromFile(const QString& uri, QString& geometryAttribute, std::list<QString>& thematicAttributes) const;

  //GML2 specific methods
  int getExtentFromGML2(QgsRect* extent, const QDomElement& wfsCollectionElement) const;
  
  int getFeaturesFromGML2(const QDomElement& wfsCollectionElement, const QString& geometryAttribute);

  int getWkbFromGML2(const QDomNode& geometryElement, unsigned char** wkb, int* wkbSize, QGis::WKBTYPE* type) const;
  /**Creates WKB from a <Point> element*/
  int getWkbFromGML2Point(const QDomElement& geometryElement, unsigned char** wkb, int* wkbSize, QGis::WKBTYPE* type) const;
  /**Creates WKB from a <Polygon> element*/
  int getWkbFromGML2Polygon(const QDomElement& geometryElement, unsigned char** wkb, int* wkbSize, QGis::WKBTYPE* type) const;
  /**Creates WKB from a <LineString> element*/
  int getWkbFromGML2LineString(const QDomElement& geometryElement, unsigned char** wkb, int* wkbSize, QGis::WKBTYPE* type) const;
  /**Creates WKB from a <MultiPoint> element*/
  int getWkbFromGML2MultiPoint(const QDomElement& geometryElement, unsigned char** wkb, int* wkbSize, QGis::WKBTYPE* type) const;
  /**Creates WKB from a <MultiLineString> element*/
  int getWkbFromGML2MultiLineString(const QDomElement& geometryElement, unsigned char** wkb, int* wkbSize, QGis::WKBTYPE* type) const;
  /**Creates WKB from a <MultiPolygon> element*/
  int getWkbFromGML2MultiPolygon(const QDomElement& geometryElement, unsigned char** wkb, int* wkbSize, QGis::WKBTYPE* type) const;
  /**Reads the <gml:coordinates> element and extracts the coordinates as points
     @param coords list where the found coordinates are appended
     @param elem the <gml:coordinates> element
     @return 0 in case of success*/
  int readGML2Coordinates(std::list<QgsPoint>& coords, const QDomElement elem) const;
  /**Tries to create a QgsSpatialRefSys object and assign it to mSourceSRS. Returns 0 in case of success*/
  int setSRSFromGML2(const QDomElement& wfsCollectionElement);
};

#endif