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>

Collaboration diagram for QgsMapCanvasSnapper:

List of all members.

Public Member Functions
	QgsMapCanvasSnapper (QgsMapCanvas *canvas)
	Constructor.
	QgsMapCanvasSnapper ()
	~QgsMapCanvasSnapper ()
void	setMapCanvas (QgsMapCanvas *canvas)
int	snapToBackgroundLayers (const QPoint &p, QList< QgsSnappingResult > &results, const QList< QgsPoint > &excludePoints=QList< QgsPoint >())
	Snaps to the background layers.
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.
Private Attributes
QgsMapCanvas *	mMapCanvas
	Pointer to the map canvas.
QgsSnapper *	mSnapper
	The object which does the snapping operations.

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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.

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Constructor & Destructor Documentation

QgsMapCanvasSnapper::QgsMapCanvasSnapper

(

QgsMapCanvas *

canvas

)

Constructor.

Parameters:

canvas

the map canvas to snap to

Definition at line 29 of file qgsmapcanvassnapper.cpp.

References QgsMapCanvas::mapRenderer(), and mSnapper.

QgsMapCanvasSnapper::QgsMapCanvasSnapper

(

)

Definition at line 41 of file qgsmapcanvassnapper.cpp.

QgsMapCanvasSnapper::~QgsMapCanvasSnapper

(

)

Definition at line 46 of file qgsmapcanvassnapper.cpp.

References mSnapper.

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Member Function Documentation

void QgsMapCanvasSnapper::setMapCanvas

(

QgsMapCanvas *

canvas

)

Definition at line 51 of file qgsmapcanvassnapper.cpp.

References QgsMapCanvas::mapRenderer(), 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:

p	start point of the snap (in pixel coordinates)
results	snapped points
excludePoints	a 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 129 of file qgsmapcanvassnapper.cpp.

References QgsGeometry::asPoint(), QgsMapCanvas::currentLayer(), QgsTolerance::defaultTolerance(), QgsGeometry::fromPolyline(), QgsMapLayerRegistry::instance(), QgsProject::instance(), QgsGeometry::intersection(), QgsMapLayerRegistry::mapLayer(), QgsMapCanvas::mapRenderer(), 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, 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:

p	start point of the snap (in pixel coordinates)
results	list to which the results are appended
snap_to	snap to vertex or to segment
snappingTol	snapping tolerance. -1 means that the search radius for vertex edits is taken
excludePoints	a 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 65 of file qgsmapcanvassnapper.cpp.

References QgsMapCanvas::currentLayer(), QgsProject::instance(), QgsMapCanvas::mapRenderer(), 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().

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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().

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

• src/gui/qgsmapcanvassnapper.h
• src/gui/qgsmapcanvassnapper.cpp