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:

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Public Member Functions
	QgsMapCanvasSnapper (QgsMapCanvas *canvas)
	Constructor.
	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.
int	snapToBackgroundLayers (const QPoint &p, QList< QgsSnappingResult > &results, const QList< QgsPoint > &excludePoints=QList< QgsPoint >())
	Snaps to the background layers.
void	setMapCanvas (QgsMapCanvas *canvas)

Private Attributes
QgsMapCanvas *	mMapCanvas
	Pointer to the map canvas.
QgsSnapper *	mSnapper
	The object which does the snapping operations.

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

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 43 of file qgsmapcanvassnapper.cpp.

QgsMapCanvasSnapper::~QgsMapCanvasSnapper ( )

Definition at line 47 of file qgsmapcanvassnapper.cpp.

References mSnapper.

Member Function Documentation

void QgsMapCanvasSnapper::setMapCanvas ( QgsMapCanvas * canvas )

Definition at line 52 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 121 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