Added select() variant with QgsFeatureRequest for simpler constructio…

…n of requests
qgis · Oct 8, 2012 · 70ff8ef · 70ff8ef
1 parent 13a6fd9
commit 70ff8ef
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Showing 11 changed files with 352 additions and 0 deletions.
diff --git a/python/core/core.sip b/python/core/core.sip
@@ -26,6 +26,7 @@
 %Include qgsdistancearea.sip
 %Include qgsexpression.sip
 %Include qgsfeature.sip
+%Include qgsfeaturerequest.sip
 %Include qgsfield.sip
 %Include qgsgeometry.sip
 %Include qgsgeometryvalidator.sip

diff --git a/python/core/qgsfeaturerequest.sip b/python/core/qgsfeaturerequest.sip
@@ -0,0 +1,32 @@
+
+class QgsFeatureRequest
+{
+%TypeHeaderCode
+#include <qgsfeaturerequest.h>
+%End
+
+public:
+  enum Flag {
+    NoGeometry     = 0x01,  //!< Do not fetch geometry
+    NoAttributes   = 0x02,  //!< Do not fetch any attributes
+    ExactIntersect = 0x04   //!< Use exact geometry intersection (slower) instead of bounding boxes
+  };
+  typedef QFlags<QgsFeatureRequest::Flag> Flags;
+
+  //! construct a default request: for all features get attributes and geometries
+  QgsFeatureRequest();
+
+  //! Set rectangle from which features will be taken. Empty rectangle removes the filter.
+  QgsFeatureRequest& setExtent(const QgsRectangle& rect);
+  const QgsRectangle& extent() const;
+
+  //! Set flags that affect how features will be fetched
+  QgsFeatureRequest& setFlags(Flags flags);
+  const Flags& flags() const;
+
+  //! Set a subset of attributes that will be fetched. Empty list means that all attributes are used.
+  //! To disable fetching attributes, reset the FetchAttributes flag (which is set by default)
+  QgsFeatureRequest& setAttributes(const QgsAttributeList& attrs);
+  const QgsAttributeList& attributes() const;
+
+};
diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
@@ -65,6 +65,7 @@ SET(QGIS_CORE_SRCS
   qgsdistancearea.cpp
   qgsexpression.cpp
   qgsfeature.cpp
+  qgsfeaturerequest.cpp
   qgsfield.cpp
   qgsgeometry.cpp
   qgsgeometryvalidator.cpp
@@ -352,6 +353,7 @@ SET(QGIS_CORE_HDRS
   qgsexception.h
   qgsexpression.h
   qgsfeature.h
+  qgsfeaturerequest.h
   qgsfield.h
   qgsgeometry.h
   qgshttptransaction.h

diff --git a/src/core/qgsfeaturerequest.cpp b/src/core/qgsfeaturerequest.cpp
@@ -0,0 +1,6 @@
+#include "qgsfeaturerequest.h"
+
+QgsFeatureRequest::QgsFeatureRequest()
+    : mFlags( 0 )
+{
+}
diff --git a/src/core/qgsfeaturerequest.h b/src/core/qgsfeaturerequest.h
@@ -0,0 +1,59 @@
+#ifndef QGSFEATUREREQUEST_H
+#define QGSFEATUREREQUEST_H
+
+#include <QFlags>
+
+#include "qgsrectangle.h"
+
+#include <QList>
+typedef QList<int> QgsAttributeList;
+
+/**
+ * This class wraps a request for features to a vector layer (or directly its vector data provider).
+ *
+ * The options may be chained, e.g.:
+ *   QgsFeatureRequest().setExtent(QgsRectangle(0,0,1,1)).setFlags(QgsFeatureRequest::ExactIntersect)
+ */
+class QgsFeatureRequest
+{
+  public:
+    enum Flag
+    {
+      NoGeometry     = 0x01,  //!< Do not fetch geometry
+      NoAttributes   = 0x02,  //!< Do not fetch any attributes
+      ExactIntersect = 0x04   //!< Use exact geometry intersection (slower) instead of bounding boxes
+    };
+    Q_DECLARE_FLAGS( Flags, Flag )
+
+    //! construct a default request: for all features get attributes and geometries
+    QgsFeatureRequest();
+
+    //! Set rectangle from which features will be taken. Empty rectangle removes the filter.
+    QgsFeatureRequest& setExtent( const QgsRectangle& rect ) { mRect = rect; return *this; }
+    const QgsRectangle& extent() const { return mRect; }
+
+    //! Set flags that affect how features will be fetched
+    QgsFeatureRequest& setFlags( Flags flags ) { mFlags = flags; return *this; }
+    const Flags& flags() const { return mFlags; }
+
+    //! Set a subset of attributes that will be fetched. Empty list means that all attributes are used.
+    //! To disable fetching attributes, reset the FetchAttributes flag (which is set by default)
+    QgsFeatureRequest& setAttributes( const QgsAttributeList& attrs ) { mAttrs = attrs; return *this; }
+    const QgsAttributeList& attributes() const { return mAttrs; }
+
+    // TODO: maybe set attributes as a list of strings?
+
+    // TODO: in future
+    // void setExpression(const QString& expression);
+    // void setLimit(int limit);
+
+  protected:
+    QgsRectangle mRect;
+    Flags mFlags;
+    QgsAttributeList mAttrs;
+};
+
+Q_DECLARE_OPERATORS_FOR_FLAGS( QgsFeatureRequest::Flags )
+
+
+#endif // QGSFEATUREREQUEST_H
diff --git a/src/core/qgsvectordataprovider.cpp b/src/core/qgsvectordataprovider.cpp
@@ -21,6 +21,7 @@
 
 #include "qgsvectordataprovider.h"
 #include "qgsfeature.h"
+#include "qgsfeaturerequest.h"
 #include "qgsfield.h"
 #include "qgslogger.h"
 #include "qgsmessagelog.h"
@@ -44,6 +45,22 @@ QString QgsVectorDataProvider::storageType() const
   return "Generic vector file";
 }
 
+
+void QgsVectorDataProvider::select( const QgsFeatureRequest& request )
+{
+  QgsAttributeList attrs;
+  if ( !( request.flags() & QgsFeatureRequest::NoAttributes ) )
+  {
+    attrs = request.attributes();
+    if ( attrs.isEmpty() ) // empty list = fetch all attributes
+      attrs = attributeIndexes();
+  }
+  bool fetchGeom = !( request.flags() & QgsFeatureRequest::NoGeometry );
+  bool exactIntersect = ( request.flags() & QgsFeatureRequest::ExactIntersect );
+  select( attrs, request.extent(), fetchGeom, exactIntersect );
+}
+
+
 long QgsVectorDataProvider::updateFeatureCount()
 {
   return -1;

diff --git a/src/core/qgsvectordataprovider.h b/src/core/qgsvectordataprovider.h
@@ -31,6 +31,8 @@ class QTextCodec;
 typedef QList<int> QgsAttributeList;
 typedef QSet<int> QgsAttributeIds;
 
+class QgsFeatureRequest;
+
 /** \ingroup core
  * This is the base class for vector data providers.
  *
@@ -114,6 +116,11 @@ class CORE_EXPORT QgsVectorDataProvider : public QgsDataProvider
                          bool fetchGeometry = true,
                          bool useIntersect = false ) = 0;
 
+    /** Select features based on criteria specified in the request
+     * @note added in 2.0
+     */
+    virtual void select( const QgsFeatureRequest& request );
+
     /**
      * This function does nothing useful, it's kept only for compatibility.
      * @todo to be removed

diff --git a/src/core/qgsvectorlayer.cpp b/src/core/qgsvectorlayer.cpp
@@ -46,6 +46,7 @@
 #include "qgsapplication.h"
 #include "qgscoordinatetransform.h"
 #include "qgsfeature.h"
+#include "qgsfeaturerequest.h"
 #include "qgsfield.h"
 #include "qgsgeometry.h"
 #include "qgslabel.h"
@@ -1743,6 +1744,22 @@ void QgsVectorLayer::select( QgsAttributeList attributes, QgsRectangle rect, boo
   }
 }
 
+
+void QgsVectorLayer::select( const QgsFeatureRequest& request )
+{
+  QgsAttributeList attrs;
+  if ( !( request.flags() & QgsFeatureRequest::NoAttributes ) )
+  {
+    attrs = request.attributes();
+    if ( attrs.isEmpty() ) // empty list = fetch all attributes
+      attrs = pendingAllAttributesList();
+  }
+  bool fetchGeom = !( request.flags() & QgsFeatureRequest::NoGeometry );
+  bool exactIntersect = ( request.flags() & QgsFeatureRequest::ExactIntersect );
+  select( attrs, request.extent(), fetchGeom, exactIntersect );
+}
+
+
 bool QgsVectorLayer::nextFeature( QgsFeature &f )
 {
   if ( !mFetching )

diff --git a/src/core/qgsvectorlayer.h b/src/core/qgsvectorlayer.h
@@ -34,6 +34,7 @@ class QImage;
 
 class QgsAttributeAction;
 class QgsCoordinateTransform;
+class QgsFeatureRequest;
 class QgsGeometry;
 class QgsGeometryVertexIndex;
 class QgsMapToPixel;
@@ -355,6 +356,11 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer
                  bool fetchGeometry = true,
                  bool useIntersect = false );
 
+    /** Select features based on criteria specified in the request
+     * @note added in 2.0
+     */
+    void select( const QgsFeatureRequest& request );
+
     /**
      * fetch a feature (after select)
      * @param feature buffer to read the feature into

diff --git a/tests/src/core/CMakeLists.txt b/tests/src/core/CMakeLists.txt
@@ -96,6 +96,7 @@ ADD_QGIS_TEST(geometrytest testqgsgeometry.cpp)
 ADD_QGIS_TEST(coordinatereferencesystemtest testqgscoordinatereferencesystem.cpp)
 ADD_DEPENDENCIES(qgis_coordinatereferencesystemtest synccrsdb)
 ADD_QGIS_TEST(pointtest testqgspoint.cpp)
+ADD_QGIS_TEST(vectordataprovidertest testqgsvectordataprovider.cpp)
 ADD_QGIS_TEST(vectorlayertest testqgsvectorlayer.cpp)
 ADD_QGIS_TEST(rulebasedrenderertest testqgsrulebasedrenderer.cpp)
 ADD_QGIS_TEST(ziplayertest testziplayer.cpp)