QGIS API Documentation  2.7.0-Master
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Modules Pages
Public Member Functions | Protected Member Functions | Protected Attributes | Friends | List of all members
QgsAbstractFeatureIterator Class Referenceabstract

Internal feature iterator to be implemented within data providers. More...

#include <qgsfeatureiterator.h>

Inheritance diagram for QgsAbstractFeatureIterator:
Inheritance graph
[legend]

Public Member Functions

 QgsAbstractFeatureIterator (const QgsFeatureRequest &request)
 base class constructor - stores the iteration parameters More...
 
virtual ~QgsAbstractFeatureIterator ()
 destructor makes sure that the iterator is closed properly More...
 
virtual bool close ()=0
 end of iterating: free the resources / lock More...
 
virtual bool nextFeature (QgsFeature &f)
 fetch next feature, return true on success More...
 
virtual bool rewind ()=0
 reset the iterator to the starting position More...
 

Protected Member Functions

void deref ()
 remove reference, delete if refs == 0 More...
 
virtual bool fetchFeature (QgsFeature &f)=0
 If you write a feature iterator for your provider, this is the method you need to implement!! More...
 
virtual bool nextFeatureFilterExpression (QgsFeature &f)
 By default, the iterator will fetch all features and check if the feature matches the expression. More...
 
virtual bool nextFeatureFilterFids (QgsFeature &f)
 By default, the iterator will fetch all features and check if the id is in the request. More...
 
virtual bool prepareSimplification (const QgsSimplifyMethod &simplifyMethod)
 Setup the simplification of geometries to fetch using the specified simplify method. More...
 
void ref ()
 add reference More...
 

Protected Attributes

bool mClosed
 Set to true, as soon as the iterator is closed. More...
 
QgsFeatureRequest mRequest
 A copy of the feature request. More...
 
int refs
 reference counting (to allow seamless copying of QgsFeatureIterator instances) More...
 

Friends

class QgsFeatureIterator
 

Detailed Description

Internal feature iterator to be implemented within data providers.

Definition at line 26 of file qgsfeatureiterator.h.

Constructor & Destructor Documentation

QgsAbstractFeatureIterator::QgsAbstractFeatureIterator ( const QgsFeatureRequest request)

base class constructor - stores the iteration parameters

Definition at line 21 of file qgsfeatureiterator.cpp.

QgsAbstractFeatureIterator::~QgsAbstractFeatureIterator ( )
virtual

destructor makes sure that the iterator is closed properly

Definition at line 30 of file qgsfeatureiterator.cpp.

Member Function Documentation

virtual bool QgsAbstractFeatureIterator::close ( )
pure virtual

end of iterating: free the resources / lock

Implemented in QgsCachedFeatureWriterIterator, QgsVectorLayerFeatureIterator, and QgsCachedFeatureIterator.

void QgsAbstractFeatureIterator::deref ( )
protected

remove reference, delete if refs == 0

Definition at line 99 of file qgsfeatureiterator.cpp.

virtual bool QgsAbstractFeatureIterator::fetchFeature ( QgsFeature f)
protectedpure virtual

If you write a feature iterator for your provider, this is the method you need to implement!!

Parameters
fThe feature to write to
Returns
true if a feature was written to f

Implemented in QgsCachedFeatureWriterIterator, QgsVectorLayerFeatureIterator, and QgsCachedFeatureIterator.

bool QgsAbstractFeatureIterator::nextFeature ( QgsFeature f)
virtual

fetch next feature, return true on success

Definition at line 36 of file qgsfeatureiterator.cpp.

bool QgsAbstractFeatureIterator::nextFeatureFilterExpression ( QgsFeature f)
protectedvirtual

By default, the iterator will fetch all features and check if the feature matches the expression.

If you have a more sophisticated metodology (SQL request for the features...) and you check for the expression in your fetchFeature method, you can just redirect this call to fetchFeature so the default check will be omitted.

Parameters
fThe feature to write to
Returns
true if a feature was written to f

Reimplemented in QgsVectorLayerFeatureIterator.

Definition at line 65 of file qgsfeatureiterator.cpp.

bool QgsAbstractFeatureIterator::nextFeatureFilterFids ( QgsFeature f)
protectedvirtual

By default, the iterator will fetch all features and check if the id is in the request.

If you have a more sophisticated metodology (SQL request for the features...) and you are sure, that any feature you return from fetchFeature will match if the request was FilterFids you can just redirect this call to fetchFeature so the default check will be omitted.

Parameters
fThe feature to write to
Returns
true if a feature was written to f

Reimplemented in QgsCachedFeatureIterator.

Definition at line 75 of file qgsfeatureiterator.cpp.

bool QgsAbstractFeatureIterator::prepareSimplification ( const QgsSimplifyMethod simplifyMethod)
protectedvirtual

Setup the simplification of geometries to fetch using the specified simplify method.

Reimplemented in QgsVectorLayerFeatureIterator.

Definition at line 106 of file qgsfeatureiterator.cpp.

void QgsAbstractFeatureIterator::ref ( )
protected

add reference

Definition at line 85 of file qgsfeatureiterator.cpp.

virtual bool QgsAbstractFeatureIterator::rewind ( )
pure virtual

reset the iterator to the starting position

Implemented in QgsCachedFeatureWriterIterator, QgsVectorLayerFeatureIterator, and QgsCachedFeatureIterator.

Friends And Related Function Documentation

friend class QgsFeatureIterator
friend

Definition at line 88 of file qgsfeatureiterator.h.

Member Data Documentation

bool QgsAbstractFeatureIterator::mClosed
protected

Set to true, as soon as the iterator is closed.

Definition at line 82 of file qgsfeatureiterator.h.

QgsFeatureRequest QgsAbstractFeatureIterator::mRequest
protected

A copy of the feature request.

Definition at line 79 of file qgsfeatureiterator.h.

int QgsAbstractFeatureIterator::refs
protected

reference counting (to allow seamless copying of QgsFeatureIterator instances)

Definition at line 85 of file qgsfeatureiterator.h.


The documentation for this class was generated from the following files: