1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
class QgsAbstractFeatureIterator
{
%TypeHeaderCode
#include <qgsfeatureiterator.h>
%End
public:
//! Status of expression compilation for filter expression requests
enum CompileStatus
{
NoCompilation, /*!< Expression could not be compiled or not attempt was made to compile expression */
PartiallyCompiled, /*!< Expression was partially compiled, but extra checks need to be applied to features*/
Compiled, /*!< Expression was fully compiled and delegated to data provider source*/
};
//! base class constructor - stores the iteration parameters
QgsAbstractFeatureIterator( const QgsFeatureRequest& request );
//! destructor makes sure that the iterator is closed properly
virtual ~QgsAbstractFeatureIterator();
//! fetch next feature, return true on success
virtual bool nextFeature( QgsFeature& f );
//! reset the iterator to the starting position
virtual bool rewind() = 0;
//! end of iterating: free the resources / lock
virtual bool close() = 0;
/** Returns the status of expression compilation for filter expression requests.
* @note added in QGIS 2.16
*/
CompileStatus compileStatus() const;
protected:
/**
* If you write a feature iterator for your provider, this is the method you
* need to implement!!
*
* @param f The feature to write to
* @return true if a feature was written to f
*/
virtual bool fetchFeature( QgsFeature& f ) = 0;
/**
* 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.
*
* @param f The feature to write to
* @return true if a feature was written to f
*/
virtual bool nextFeatureFilterExpression( QgsFeature &f );
/**
* 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.
*
* @param f The feature to write to
* @return true if a feature was written to f
*/
virtual bool nextFeatureFilterFids( QgsFeature & f );
void ref(); //!< add reference
void deref(); //!< remove reference, delete if refs == 0
//! Setup the simplification of geometries to fetch using the specified simplify method
virtual bool prepareSimplification( const QgsSimplifyMethod& simplifyMethod );
};
class QgsFeatureIterator
{
%TypeHeaderCode
#include <qgsfeatureiterator.h>
%End
public:
QgsFeatureIterator* __iter__();
%MethodCode
sipRes = sipCpp;
%End
SIP_PYOBJECT __next__();
%MethodCode
QgsFeature* f = new QgsFeature;
if (sipCpp->nextFeature(*f))
sipRes = sipConvertFromType(f, sipType_QgsFeature, Py_None);
else
{
delete f;
PyErr_SetString(PyExc_StopIteration,"");
}
%End
//! construct invalid iterator
QgsFeatureIterator();
//! construct a valid iterator
// QgsFeatureIterator( QgsAbstractFeatureIterator* iter );
//! copy constructor copies the iterator, increases ref.count
QgsFeatureIterator( const QgsFeatureIterator& fi );
//! destructor deletes the iterator if it has no more references
~QgsFeatureIterator();
// QgsFeatureIterator& operator=(const QgsFeatureIterator& other);
bool nextFeature( QgsFeature& f );
bool rewind();
bool close();
//! find out whether the iterator is still valid or closed already
bool isClosed() const;
/** Returns the status of expression compilation for filter expression requests.
* @note added in QGIS 2.16
*/
QgsAbstractFeatureIterator::CompileStatus compileStatus() const;
};
|
