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QgsMapCanvasSnapper Class Reference

This class reads the snapping properties from the current project and configures a QgsSnapper to perform the snapping. More...

#include <qgsmapcanvassnapper.h>

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Public Member Functions

 QgsMapCanvasSnapper (QgsMapCanvas *canvas)
 Constructor. More...
 
 QgsMapCanvasSnapper ()
 
 ~QgsMapCanvasSnapper ()
 
int snapToCurrentLayer (const QPoint &p, QList< QgsSnappingResult > &results, QgsSnapper::SnappingType snap_to, double snappingTol=-1, const QList< QgsPoint > &excludePoints=QList< QgsPoint >())
 Does a snap to the current layer. More...
 
int snapToBackgroundLayers (const QPoint &p, QList< QgsSnappingResult > &results, const QList< QgsPoint > &excludePoints=QList< QgsPoint >())
 Snaps to the background layers. More...
 
void setMapCanvas (QgsMapCanvas *canvas)
 

Private Attributes

QgsMapCanvasmMapCanvas
 Pointer to the map canvas. More...
 
QgsSnappermSnapper
 The object which does the snapping operations. More...
 

Detailed Description

This class reads the snapping properties from the current project and configures a QgsSnapper to perform the snapping.

Snapping can be done to the active layer (useful for selecting a vertex to manipulate) or to background layers

Definition at line 33 of file qgsmapcanvassnapper.h.

Constructor & Destructor Documentation

QgsMapCanvasSnapper::QgsMapCanvasSnapper ( QgsMapCanvas canvas)

Constructor.

Parameters
canvasthe map canvas to snap to

Definition at line 29 of file qgsmapcanvassnapper.cpp.

References QgsMapCanvas::mapSettings(), and mSnapper.

QgsMapCanvasSnapper::QgsMapCanvasSnapper ( )

Definition at line 39 of file qgsmapcanvassnapper.cpp.

QgsMapCanvasSnapper::~QgsMapCanvasSnapper ( )

Definition at line 43 of file qgsmapcanvassnapper.cpp.

References mSnapper.

Member Function Documentation

void QgsMapCanvasSnapper::setMapCanvas ( QgsMapCanvas canvas)

Definition at line 48 of file qgsmapcanvassnapper.cpp.

References QgsMapCanvas::mapSettings(), mMapCanvas, and mSnapper.

int QgsMapCanvasSnapper::snapToBackgroundLayers ( const QPoint &  p,
QList< QgsSnappingResult > &  results,
const QList< QgsPoint > &  excludePoints = QList<QgsPoint>() 
)

Snaps to the background layers.

This method is useful to align the features of the edited layers to those of other layers (as described in the project properties). Uses snap mode QgsSnapper::SnapWithOneResult. Therefore, only the closest result is returned.

Parameters
pstart point of the snap (in pixel coordinates)
resultssnapped points
excludePointsa list with (map coordinate) points that should be excluded in the snapping result. Useful e.g. for vertex moves where a vertex should not be snapped to its original position
Returns
0 in case of success

Definition at line 117 of file qgsmapcanvassnapper.cpp.

References QgsGeometry::asPoint(), QgsMapCanvas::currentLayer(), QgsTolerance::defaultTolerance(), QgsGeometry::distance(), QgsGeometry::fromPoint(), QgsGeometry::fromPolyline(), QgsMapCanvas::getCoordinateTransform(), QgsVectorLayer::hasGeometryType(), QgsMapLayerRegistry::instance(), QgsProject::instance(), QgsGeometry::intersection(), QgsMapLayerRegistry::mapLayer(), QgsMapCanvas::mapSettings(), QgsTolerance::MapUnits, QgsSnapper::SnapLayer::mLayer, mMapCanvas, mSnapper, QgsSnapper::SnapLayer::mSnapTo, QgsSnapper::SnapLayer::mTolerance, QgsSnapper::SnapLayer::mUnitType, QGis::Point, QgsDebugMsg, QgsProject::readListEntry(), QgsProject::readNumEntry(), QgsSnapper::setSnapLayers(), QgsSnapper::setSnapMode(), QgsSnapper::snapPoint(), QgsSnapper::SnapToSegment, QgsSnapper::SnapToVertex, QgsSnapper::SnapToVertexAndSegment, QgsSnapper::SnapWithOneResult, QgsSnapper::SnapWithResultsForSamePosition, QgsSnapper::SnapWithResultsWithinTolerances, QgsTolerance::toleranceInMapUnits(), QgsMapToPixel::toMapCoordinates(), and QgsGeometry::type().

int QgsMapCanvasSnapper::snapToCurrentLayer ( const QPoint &  p,
QList< QgsSnappingResult > &  results,
QgsSnapper::SnappingType  snap_to,
double  snappingTol = -1,
const QList< QgsPoint > &  excludePoints = QList<QgsPoint>() 
)

Does a snap to the current layer.

Uses snap mode QgsSnapper::SnapWithResultsForSamePosition if topological editing is enabled and QgsSnapper::SnapWithOneResult_BY_SEGMENT if not. As this method is usually used to find vertices/segments for editing operations, it uses the search radius for vertex editing from the qgis options.

Parameters
pstart point of the snap (in pixel coordinates)
resultslist to which the results are appended
snap_tosnap to vertex or to segment
snappingTolsnapping tolerance. -1 means that the search radius for vertex edits is taken
excludePointsa list with (map coordinate) points that should be excluded in the snapping result. Useful e.g. for vertex moves where a vertex should not be snapped to its original position

Definition at line 62 of file qgsmapcanvassnapper.cpp.

References QgsMapCanvas::currentLayer(), QgsProject::instance(), QgsMapCanvas::mapSettings(), QgsTolerance::MapUnits, QgsSnapper::SnapLayer::mLayer, mMapCanvas, mSnapper, QgsSnapper::SnapLayer::mSnapTo, QgsSnapper::SnapLayer::mTolerance, QgsSnapper::SnapLayer::mUnitType, QgsProject::readNumEntry(), QgsSnapper::setSnapLayers(), QgsSnapper::setSnapMode(), QgsSnapper::snapPoint(), QgsSnapper::SnapWithOneResult, QgsSnapper::SnapWithResultsForSamePosition, and QgsTolerance::vertexSearchRadius().

Member Data Documentation

QgsMapCanvas* QgsMapCanvasSnapper::mMapCanvas
private

Pointer to the map canvas.

Definition at line 69 of file qgsmapcanvassnapper.h.

Referenced by setMapCanvas(), snapToBackgroundLayers(), and snapToCurrentLayer().

QgsSnapper* QgsMapCanvasSnapper::mSnapper
private

The object which does the snapping operations.

Definition at line 71 of file qgsmapcanvassnapper.h.

Referenced by QgsMapCanvasSnapper(), setMapCanvas(), snapToBackgroundLayers(), snapToCurrentLayer(), and ~QgsMapCanvasSnapper().


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