qgsmysqlprovider.h

一个非常好的GIS开源新版本

/***************************************************************************
      qgsmysqlprovider.h  -  Data provider for MySQL 5.0+
                             -------------------
    begin                : 2006-01-07 
    copyright            : (C) 2006 by Gary E.Sherman
    email                : sherman at mrcc.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.                                   *
 *                                                                         *
 ***************************************************************************/

/* $Id:  */

#include "../../src/qgsvectordataprovider.h"


#include <map>

#include "qgsdatasourceuri.h"
extern "C"{
#include <mysql.h>
}


class QgsFeature;
class QgsField;


/**
\class QgsMySQLProvider
\brief Data provider for MySQL
*/
class QgsMySQLProvider : public QgsVectorDataProvider
{
public:
/*
 * Constructor for the provider
* The uri for a MySQL connection must include all needed parameters
* to make the connection:
* host=localhost user=gsherman dbname=test password=xxx table=test.alaska (the_geom)
*/
  QgsMySQLProvider(QString const & uri = "");

  virtual ~ QgsMySQLProvider();

  /**
    *   Returns the permanent storage type for this layer as a friendly name.
    */
  QString storageType();

  /** get the first feature

    mFile should be open with the file pointer at the record of the next
    feature, or EOF.  The feature found on the current line is parsed.

    @param feature the feature object to be populated with next feature
    @param fetchAttributes is true if you want to get the feature attributes, too

    The search will be limited to the search region if one is active.

    @return found QgsFeature, or null if not found
  */
  QgsFeature *getFirstFeature(bool fetchAttributes = false);

  /** Get the next feature, if any

    mFile should be open with the file pointer at the record of the next
    feature, or EOF.  The feature found on the current line is parsed.

    @param feature the feature object to be populated with next feature
    @param fetchAttributes is true if you want to get the feature attributes, too

    The search will be limited to the search region if one is active.

  * @return found QgsFeature, or null if not found
  */
  QgsFeature *getNextFeature(bool fetchAttributes = false);

  /** get the next feature, if any

    mFile should be open with the file pointer at the record of the next
    feature, or EOF.  The feature found on the current line is parsed.

    @param feature the feature object to be populated with next feature
    @param fetchAttributes is true if you want to get the feature attributes, too

    @return false if unable to get the next feature

    @note that feature will also be set invalid if unable to locate the next
    feature

    The search will be limited to the search region if one is active.
*/
  /** Used to ask the layer for its projection as a WKT string. Implements
  virtual method of same name in QgsDataProvider. */
  QString getProjectionWKT()  {return QString("Not implemented yet");} ;

  /**
  * Get the first feature resulting from a select operation
  * @return QgsFeature
  */
  bool getNextFeature(QgsFeature & feature, bool fetchAttributes = false);

  /** get the next feature, if any

    mFile should be open with the file pointer at the record of the next
    feature, or EOF.  The feature found on the current line is parsed.

    @param feature the feature object to be populated with next feature @param
           attlist is list of attributes by their field positions to fetch
                   with object

    @return false if unable to get the next feature

    @note That feature will also be set invalid if unable to locate the next
    feature.

    The search will be limited to the search region if one is active.

  */
  QgsFeature *getNextFeature(std::list<int> const & desiredAttributes, int featureQueueSize = 1);


  /** Get the feature type. This corresponds to 
      WKBPoint,
      WKBLineString,
      WKBPolygon,
      WKBMultiPoint,
      WKBMultiLineString or
      WKBMultiPolygon
  * as defined in qgis.h
  * This provider will always return WKBPoint
  */
  int geometryType() const;


  /** return the number of layers for the current data source

  @note 

  Should this be subLayerCount() instead?
  */
  size_t layerCount() const;



    /** 
    * Get the number of features in the layer
    */
  long featureCount() const;
    /** 
    * Get the number of fields in the layer
    */
  int fieldCount() const;
  /**
  * Select features based on a bounding rectangle. Features can be retrieved 
  * with calls to getFirstFeature and getNextFeature.
  * @param mbr QgsRect containing the extent to use in selecting features
  */
  void select(QgsRect * mbr, bool useIntersect = false);

  /**
  * Identify features within the search radius specified by rect
  * @param rect Bounding rectangle of search radius
  * @return std::vector containing QgsFeature objects that intersect rect
  */
  virtual std::vector < QgsFeature > &identify(QgsRect * rect);

  /** Return the extent for this data layer
  */
  virtual QgsRect *extent();
  /**
  * Get the attributes associated with a feature
  */
  void getFeatureAttributes(int key, QgsFeature * f);
 /**
 * Get the field information for the layer
 */
    std::vector<QgsField> const & fields() const;

  /* Reset the layer (ie move the file pointer to the head
     of the file.
   */
  void reset();

 /**Returns the minimum value of an attribute
    @param position the number of the attribute*/
  QString minValue(int position);

 /**Returns the maximum value of an attribute
    @param position the number of the attribute*/
  QString maxValue(int position);

 /**Returns true if this is a valid delimited file
 */
  bool isValid();

 /**
  * Check to see if the point is withn the selection
  * rectangle
  * @param x X value of point
  * @param y Y value of point
  * @return True if point is within the rectangle
  */
  bool boundsCheck(double x, double y);

  int capabilities() const;

  //! Save the layer as a shapefile
  bool saveAsShapefile();

  QgsDataSourceURI *getURI()
  {
    return 0;
  };
  /** The MySQL provider does not do its own transforms so we return
     * false for the following three functions to indicate that transforms
     * should be handled by the QgsCoordinateTransform object. See the
     * documentation on QgsVectorDataProvider for details on these functions.
     */
    bool supportsNativeTransform(){return false;}
    bool usesSrid(){return false;}
    bool usesWKT(){return false;}

      /** return a provider name

      Essentially just returns the provider key.  Should be used to build file
      dialogs so that providers can be shown with their supported types. Thus
      if more than one provider supports a given format, the user is able to
      select a specific provider to open that file.

      @note

      Instead of being pure virtual, might be better to generalize this
      behavior and presume that none of the sub-classes are going to do
      anything strange with regards to their name or description?

      */
    QString name() const;


    /** return description

      Return a terse string describing what the provider is.

      @note

      Instead of being pure virtual, might be better to generalize this
      behavior and presume that none of the sub-classes are going to do
      anything strange with regards to their name or description?

     */
    QString description() const;




private:

  /** get the next feature, if any

    mFile should be open with the file pointer at the record of the next
    feature, or EOF.  The feature found on the current line is parsed.

    @param feature the feature object to be populated with next feature
    @param getAttributes is true if you want to get the feature attributes, too
    
    @param desiredAttributes attributes fields to be collected for the feature
                             as denoted by their position

    @return false if unable to get the next feature
  */
  bool getNextFeature_( QgsFeature & feature, 
                        bool getAttributes, 
                        std::list<int> const * desiredAttributes = 0 );

  void fillMinMaxCash();

  int *getFieldLengths();

  //! Fields
  std::vector < QgsField > attributeFields;

  //! Map to store field position by name
  std::map < QString, int >fieldPositions;

  QString mFileName;
  QString mDelimiter;
  QString mXField;
  QString mYField;

  //! Layer extent
  QgsRect *mExtent;

  //! Current selection rectangle

  QgsRect *mSelectionRectangle;

  bool mValid;

  int mGeomType;

  long mNumberFeatures;

  //! Feature id
  long mFid;

  /**Flag indicating, if the minmaxcache should be renewed (true) or not (false)*/
  bool mMinMaxCacheDirty;

  /**Matrix storing the minimum and maximum values*/
  double **mMinMaxCache;

  /**Fills the cash and sets minmaxcachedirty to false*/
  void mFillMinMaxCash();
  
  //! Data source URI struct for this layer
  QgsDataSourceURI mUri;

   /**
    * Flag indicating if the layer data source is a valid MySQL layer
    */
    bool valid;
    /**
     * Name of the table with no schema
     */
    QString mTableName;
    /**
     * Name of the table with schema included
     */
    QString mSchemaTableName;
    /** 
     * Name of the schema
     */
    QString mSchemaName;
    /**
     * SQL statement used to limit the features retreived
     */
    QString sqlWhereClause;
    /**
     * Primary key column for fetching features. If there is no primary key
     * the oid is used to fetch features.
     */
    QString primaryKey;
    /**
     * Data type for the primary key
     */
    QString primaryKeyType;
    /**
     * Name of the geometry column in the table
     */
    QString geometryColumn;
    /**
     * MySQL structure
     */
    MYSQL mysql;

  struct wkbPoint
  {
    unsigned char byteOrder;
    quint32 wkbType;
    double x;
    double y;
  };
  wkbPoint mWKBpt;

};