QGIS API Documentation  3.9.0-Master (635e245143)
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QgsPointLocator Class Reference

The class defines interface for querying point location: More...

#include <qgspointlocator.h>

Inheritance diagram for QgsPointLocator:
Inheritance graph
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Classes

struct  Match
 
struct  MatchFilter
 Interface that allows rejection of some matches in intersection queries (e.g. More...
 

Public Types

typedef class QList< QgsPointLocator::MatchMatchList
 
enum  Type {
  Invalid = 0, Vertex = 1, Edge = 2, Area = 4,
  All = Vertex | Edge | Area
}
 The type of a snap result or the filter type for a snap request. More...
 

Signals

void initFinished (bool ok)
 Emitted whenever index has been built and initialization is finished. More...
 

Public Member Functions

 QgsPointLocator (QgsVectorLayer *layer, const QgsCoordinateReferenceSystem &destinationCrs=QgsCoordinateReferenceSystem(), const QgsCoordinateTransformContext &transformContext=QgsCoordinateTransformContext(), const QgsRectangle *extent=nullptr, bool asynchronous=false)
 Construct point locator for a layer. More...
 
 ~QgsPointLocator () override
 
int cachedGeometryCount () const
 Returns how many geometries are cached in the index. More...
 
QgsCoordinateReferenceSystem destinationCrs () const
 Gets destination CRS - may be an invalid QgsCoordinateReferenceSystem if not doing OTF reprojection. More...
 
MatchList edgesInRect (const QgsRectangle &rect, QgsPointLocator::MatchFilter *filter=nullptr)
 Find edges within a specified recangle Optional filter may discard unwanted matches. More...
 
MatchList edgesInRect (const QgsPointXY &point, double tolerance, QgsPointLocator::MatchFilter *filter=nullptr)
 Override of edgesInRect that construct rectangle from a center point and tolerance. More...
 
const QgsRectangleextent () const
 Gets extent of the area point locator covers - if nullptr then it caches the whole layer. More...
 
bool hasIndex () const
 Indicate whether the data have been already indexed. More...
 
bool init (int maxFeaturesToIndex=-1)
 Prepare the index for queries. More...
 
bool isIndexing () const
 Returns true if the point locator is currently indexing the data. More...
 
QgsVectorLayerlayer () const
 Gets associated layer. More...
 
Match nearestArea (const QgsPointXY &point, double tolerance, QgsPointLocator::MatchFilter *filter=nullptr)
 Find nearest area to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches. More...
 
Match nearestEdge (const QgsPointXY &point, double tolerance, QgsPointLocator::MatchFilter *filter=nullptr)
 Find nearest edge to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches. More...
 
Match nearestVertex (const QgsPointXY &point, double tolerance, QgsPointLocator::MatchFilter *filter=nullptr)
 Find nearest vertex to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches. More...
 
MatchList pointInPolygon (const QgsPointXY &point)
 find out if the point is in any polygons More...
 
void setExtent (const QgsRectangle *extent)
 Configure extent - if not nullptr, it will index only that area. More...
 
void setRenderContext (const QgsRenderContext *context)
 Configure render context - if not nullptr, it will use to index only visible feature. More...
 
MatchList verticesInRect (const QgsRectangle &rect, QgsPointLocator::MatchFilter *filter=nullptr)
 Find vertices within a specified recangle Optional filter may discard unwanted matches. More...
 
MatchList verticesInRect (const QgsPointXY &point, double tolerance, QgsPointLocator::MatchFilter *filter=nullptr)
 Override of verticesInRect that construct rectangle from a center point and tolerance. More...
 

Protected Slots

void destroyIndex ()
 

Protected Member Functions

bool rebuildIndex (int maxFeaturesToIndex=-1)
 

Friends

class QgsPointLocator_VisitorArea
 
class QgsPointLocator_VisitorEdgesInRect
 
class QgsPointLocator_VisitorNearestEdge
 
class QgsPointLocator_VisitorNearestVertex
 
class QgsPointLocator_VisitorVerticesInRect
 
class QgsPointLocatorInitTask
 
class TestQgsPointLocator
 

Detailed Description

The class defines interface for querying point location:

Works with one layer.

Since
QGIS 2.8

Definition at line 56 of file qgspointlocator.h.

Member Typedef Documentation

◆ MatchList

Definition at line 224 of file qgspointlocator.h.

Member Enumeration Documentation

◆ Type

The type of a snap result or the filter type for a snap request.

Enumerator
Invalid 

Invalid.

Vertex 

Snapped to a vertex. Can be a vertex of the geometry or an intersection.

Edge 

Snapped to an edge.

Area 

Snapped to an area.

All 

Combination of vertex, edge and area.

Definition at line 115 of file qgspointlocator.h.

Constructor & Destructor Documentation

◆ QgsPointLocator()

QgsPointLocator::QgsPointLocator ( QgsVectorLayer layer,
const QgsCoordinateReferenceSystem destinationCrs = QgsCoordinateReferenceSystem(),
const QgsCoordinateTransformContext transformContext = QgsCoordinateTransformContext(),
const QgsRectangle extent = nullptr,
bool  asynchronous = false 
)
explicit

Construct point locator for a layer.

If a valid QgsCoordinateReferenceSystem is passed for destinationCrs then the locator will do the searches on data reprojected to the given CRS. For accurate reprojection it is important to set the correct transformContext if a destinationCrs is specified. This is usually taken from the current QgsProject::transformContext().

if asynchronous is false, point locator init() method will block until point locator index is completely built. if true, index building will be done in another thread and init() method returns immediately. initFinished() signal will be emitted once the initialization is over.

If extent is not nullptr, the locator will index only a subset of the layer which falls within that extent.

Definition at line 529 of file qgspointlocator.cpp.

◆ ~QgsPointLocator()

QgsPointLocator::~QgsPointLocator ( )
override

Definition at line 551 of file qgspointlocator.cpp.

Member Function Documentation

◆ cachedGeometryCount()

int QgsPointLocator::cachedGeometryCount ( ) const
inline

Returns how many geometries are cached in the index.

Since
QGIS 2.14

Definition at line 294 of file qgspointlocator.h.

◆ destinationCrs()

QgsCoordinateReferenceSystem QgsPointLocator::destinationCrs ( ) const

Gets destination CRS - may be an invalid QgsCoordinateReferenceSystem if not doing OTF reprojection.

Since
QGIS 2.14

Definition at line 556 of file qgspointlocator.cpp.

◆ destroyIndex

void QgsPointLocator::destroyIndex ( )
protectedslot

Definition at line 798 of file qgspointlocator.cpp.

◆ edgesInRect() [1/2]

QgsPointLocator::MatchList QgsPointLocator::edgesInRect ( const QgsRectangle rect,
QgsPointLocator::MatchFilter filter = nullptr 
)

Find edges within a specified recangle Optional filter may discard unwanted matches.

Definition at line 993 of file qgspointlocator.cpp.

◆ edgesInRect() [2/2]

QgsPointLocator::MatchList QgsPointLocator::edgesInRect ( const QgsPointXY point,
double  tolerance,
QgsPointLocator::MatchFilter filter = nullptr 
)

Override of edgesInRect that construct rectangle from a center point and tolerance.

Definition at line 1009 of file qgspointlocator.cpp.

◆ extent()

const QgsRectangle* QgsPointLocator::extent ( ) const
inline

Gets extent of the area point locator covers - if nullptr then it caches the whole layer.

Since
QGIS 2.14

Definition at line 98 of file qgspointlocator.h.

◆ hasIndex()

bool QgsPointLocator::hasIndex ( ) const

Indicate whether the data have been already indexed.

Definition at line 647 of file qgspointlocator.cpp.

◆ init()

bool QgsPointLocator::init ( int  maxFeaturesToIndex = -1)

Prepare the index for queries.

Does nothing if the index already exists. If the number of features is greater than the value of maxFeaturesToIndex, creation of index is stopped to make sure we do not run out of memory. If maxFeaturesToIndex is -1, no limits are used.

This method is either blocking or non blocking according to asynchronous parameter passed in the constructor. Returns false if the creation of index is blocking and has been prematurely stopped due to the limit of features, otherwise true

See also
QgsPointLocator()

Definition at line 612 of file qgspointlocator.cpp.

◆ initFinished

void QgsPointLocator::initFinished ( bool  ok)
signal

Emitted whenever index has been built and initialization is finished.

Parameters
okfalse if the creation of index has been prematurely stopped due to the limit of features, otherwise true

◆ isIndexing()

bool QgsPointLocator::isIndexing ( ) const
inline

Returns true if the point locator is currently indexing the data.

This method is useful if constructor parameter asynchronous is true

See also
QgsPointLocator()

Definition at line 302 of file qgspointlocator.h.

◆ layer()

QgsVectorLayer* QgsPointLocator::layer ( ) const
inline

Gets associated layer.

Since
QGIS 2.14

Definition at line 86 of file qgspointlocator.h.

◆ nearestArea()

QgsPointLocator::Match QgsPointLocator::nearestArea ( const QgsPointXY point,
double  tolerance,
QgsPointLocator::MatchFilter filter = nullptr 
)

Find nearest area to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches.

This will first perform a pointInPolygon and return first result. If no match is found and tolerance is not 0, it will return nearestEdge.

Since
QGIS 3.0

Definition at line 963 of file qgspointlocator.cpp.

◆ nearestEdge()

QgsPointLocator::Match QgsPointLocator::nearestEdge ( const QgsPointXY point,
double  tolerance,
QgsPointLocator::MatchFilter filter = nullptr 
)

Find nearest edge to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches.

Definition at line 945 of file qgspointlocator.cpp.

◆ nearestVertex()

QgsPointLocator::Match QgsPointLocator::nearestVertex ( const QgsPointXY point,
double  tolerance,
QgsPointLocator::MatchFilter filter = nullptr 
)

Find nearest vertex to the specified point - up to distance specified by tolerance Optional filter may discard unwanted matches.

Definition at line 931 of file qgspointlocator.cpp.

◆ pointInPolygon()

QgsPointLocator::MatchList QgsPointLocator::pointInPolygon ( const QgsPointXY point)

find out if the point is in any polygons

Definition at line 1033 of file qgspointlocator.cpp.

◆ rebuildIndex()

bool QgsPointLocator::rebuildIndex ( int  maxFeaturesToIndex = -1)
protected

Definition at line 667 of file qgspointlocator.cpp.

◆ setExtent()

void QgsPointLocator::setExtent ( const QgsRectangle extent)

Configure extent - if not nullptr, it will index only that area.

Since
QGIS 2.14

Definition at line 561 of file qgspointlocator.cpp.

◆ setRenderContext()

void QgsPointLocator::setRenderContext ( const QgsRenderContext context)

Configure render context - if not nullptr, it will use to index only visible feature.

Since
QGIS 3.2

Definition at line 572 of file qgspointlocator.cpp.

◆ verticesInRect() [1/2]

QgsPointLocator::MatchList QgsPointLocator::verticesInRect ( const QgsRectangle rect,
QgsPointLocator::MatchFilter filter = nullptr 
)

Find vertices within a specified recangle Optional filter may discard unwanted matches.

Since
QGIS 3.6

Definition at line 1015 of file qgspointlocator.cpp.

◆ verticesInRect() [2/2]

QgsPointLocator::MatchList QgsPointLocator::verticesInRect ( const QgsPointXY point,
double  tolerance,
QgsPointLocator::MatchFilter filter = nullptr 
)

Override of verticesInRect that construct rectangle from a center point and tolerance.

Since
QGIS 3.6

Definition at line 1027 of file qgspointlocator.cpp.

Friends And Related Function Documentation

◆ QgsPointLocator_VisitorArea

friend class QgsPointLocator_VisitorArea
friend

Definition at line 357 of file qgspointlocator.h.

◆ QgsPointLocator_VisitorEdgesInRect

Definition at line 358 of file qgspointlocator.h.

◆ QgsPointLocator_VisitorNearestEdge

Definition at line 356 of file qgspointlocator.h.

◆ QgsPointLocator_VisitorNearestVertex

Definition at line 355 of file qgspointlocator.h.

◆ QgsPointLocator_VisitorVerticesInRect

Definition at line 359 of file qgspointlocator.h.

◆ QgsPointLocatorInitTask

friend class QgsPointLocatorInitTask
friend

Definition at line 360 of file qgspointlocator.h.

◆ TestQgsPointLocator

friend class TestQgsPointLocator
friend

Definition at line 361 of file qgspointlocator.h.


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