SnapManager Class Reference

Class to coordinate snapping operations. More...

#include <snap.h>

Public Types
enum	Transformation {   TRANSLATE , SCALE , STRETCH , SKEW ,   ROTATE }
typedef std::list< const Inkscape::Snapper * >	SnapperList

Public Member Functions
	SnapManager (SPNamedView const *v, Inkscape::SnapPreferences &preferences)
	Construct a SnapManager for a SPNamedView.
	~SnapManager ()
bool	someSnapperMightSnap (bool immediately=true) const
	Return true if any snapping might occur, whether its to grids, guides or objects.
bool	gridSnapperMightSnap () const
void	setup (SPDesktop const *desktop, bool snapindicator=true, SPObject const *item_to_ignore=nullptr, std::vector< Inkscape::SnapCandidatePoint > *unselected_nodes=nullptr)
	Convenience shortcut when there is only one item to ignore.
void	setup (SPDesktop const *desktop, bool snapindicator, std::vector< SPObject const * > &objects_to_ignore, std::vector< Inkscape::SnapCandidatePoint > *unselected_nodes=nullptr)
	Prepare the snap manager for the actual snapping, which includes building a list of snap targets to ignore and toggling the snap indicator.
void	setupIgnoreSelection (SPDesktop const *desktop, bool snapindicator=true, std::vector< Inkscape::SnapCandidatePoint > *unselected_nodes=nullptr)
	Setup, taking the list of items to ignore from the desktop's selection.
void	unSetup ()
void	setRotationCenterSource (const std::vector< SPItem * > &items)
const std::vector< SPItem * > &	getRotationCenterSource ()
void	freeSnapReturnByRef (Geom::Point &p, Inkscape::SnapSourceType const source_type, Geom::OptRect const &bbox_to_snap=Geom::OptRect()) const
	Try to snap a point to grids, guides or objects.
Inkscape::SnappedPoint	freeSnap (Inkscape::SnapCandidatePoint const &p, Geom::OptRect const &bbox_to_snap=Geom::OptRect(), bool to_path_only=false) const
	Try to snap a point to grids, guides or objects.
void	preSnap (Inkscape::SnapCandidatePoint const &p, bool to_path_only=false)
Geom::Point	multipleOfGridPitch (Geom::Point const &t, Geom::Point const &origin)
	Snap to the closest multiple of a grid pitch.
void	constrainedSnapReturnByRef (Geom::Point &p, Inkscape::SnapSourceType const source_type, Inkscape::Snapper::SnapConstraint const &constraint, Geom::OptRect const &bbox_to_snap=Geom::OptRect()) const
	Try to snap a point along a constraint line to grids, guides or objects.
Inkscape::SnappedPoint	constrainedSnap (Inkscape::SnapCandidatePoint const &p, Inkscape::Snapper::SnapConstraint const &constraint, Geom::OptRect const &bbox_to_snap=Geom::OptRect()) const
	Try to snap a point along a constraint line to grids, guides or objects.
Inkscape::SnappedPoint	multipleConstrainedSnaps (Inkscape::SnapCandidatePoint const &p, std::vector< Inkscape::Snapper::SnapConstraint > const &constraints, bool dont_snap=false, Geom::OptRect const &bbox_to_snap=Geom::OptRect()) const
Inkscape::SnappedPoint	constrainedAngularSnap (Inkscape::SnapCandidatePoint const &p, std::optional< Geom::Point > const &p_ref, Geom::Point const &o, unsigned const snaps) const
	Try to snap a point to something at a specific angle.
void	guideFreeSnap (Geom::Point &p, Geom::Point &origin_or_vector, bool origin, bool freeze_angle) const
	Wrapper method to make snapping of the guide origin a bit easier (i.e.
void	guideConstrainedSnap (Geom::Point &p, SPGuide const &guideline) const
	Wrapper method to make snapping of the guide origin a bit easier (i.e.
SnapperList	getSnappers () const
	Return a list of snappers.
SnapperList	getGridSnappers () const
	Return a list of gridsnappers.
SPDesktop const *	getDesktop () const
SPNamedView const *	getNamedView () const
SPDocument *	getDocument () const
SPGuide const *	getGuideToIgnore () const
SPPage const *	getPageToIgnore () const
bool	getSnapIndicator () const
Inkscape::SnappedPoint	findBestSnap (Inkscape::SnapCandidatePoint const &p, IntermSnapResults const &isr, bool constrained, bool allowOffScreen=false, bool to_paths_only=false) const
	Given a set of possible snap targets, find the best target (which is not necessarily also the nearest target), and show the snap indicator if requested.
void	displaySnapsource (Inkscape::SnapCandidatePoint const &p) const
	Mark the location of the snap source (not the snap target!) on the canvas by drawing a symbol.
void	snapTransformed (std::vector< Inkscape::SnapCandidatePoint > const &points, Geom::Point const &pointer, Inkscape::PureTransform &transform)
	Method for snapping sets of points while they are being transformed.

Public Attributes
Inkscape::GuideSnapper	guide
	guide snapper
Inkscape::ObjectSnapper	object
	snapper to other objects
Inkscape::AlignmentSnapper	alignment
	snapper to align with other objects
Inkscape::DistributionSnapper	distribution
Inkscape::SnapPreferences &	snapprefs

Protected Attributes
SPNamedView const *	_named_view

Private Member Functions
void	_findCandidates (SPObject *parent, std::vector< SPObject const * > const *it, Geom::Rect const &bbox_to_snap, bool const _clip_or_mask, Geom::Affine const additional_affine)
	Find all items within snapping range.

Private Attributes
std::vector< SPObject const * >	_objects_to_ignore
	Items that should not be snapped to, for example the items that are currently being dragged. Set using the setup() method.
std::vector< SPItem * >	_rotation_center_source_items
SPDesktop const *	_desktop
bool	_snapindicator
	When true, an indicator will be drawn at the position that was being snapped to.
std::vector< Inkscape::SnapCandidatePoint > *	_unselected_nodes
	Nodes of the path that is currently being edited and which have not been selected and which will therefore be stationary. Only these nodes will be considered for snapping to. Of each unselected node both the position (Geom::Point) and the type (Inkscape::SnapTargetType) will be stored.
bool	_findCandidates_already_called
std::unique_ptr< std::vector< Inkscape::SnapCandidateItem > >	_obj_snapper_candidates
std::unique_ptr< std::vector< Inkscape::SnapCandidateItem > >	_align_snapper_candidates

Friends
class	Inkscape::ObjectSnapper
class	Inkscape::AlignmentSnapper
class	Inkscape::DistributionSnapper

Detailed Description

Class to coordinate snapping operations.

The SnapManager class handles most (if not all) of the interfacing of the snapping mechanisms with the other parts of the code base. It stores the references to the various types of snappers for grid, guides and objects, and it stores most of the snapping preferences. Besides that it provides methods to setup the snapping environment (e.g. keeps a list of the items to ignore when looking for snap target candidates, and toggling of the snap indicator), and it provides many different methods for snapping queries (free snapping vs. constrained snapping, returning the result by reference or through a return statement, etc.)

Each SPNamedView has one of these. It offers methods to snap points to whatever snappers are defined (e.g. grid, guides etc.). It also allows callers to snap points which have undergone some transformation (e.g. translation, scaling etc.)

How snapping is implemented in Inkscape

The snapping system consists of two key elements. The first one is the snap manager (this class), which keeps some data about objects in the document and answers queries of the type "given this point and type of transformation, what is the best place to snap to?".

The second is in event-context.cpp and implements the snapping timeout. Whenever a motion events happens over the canvas, it stores it for later use and initiates a timeout. This timeout is discarded whenever a new motion event occurs. When the timeout expires, a global flag in SnapManager, accessed via getSnapPostponedGlobally(), is set to true and the stored event is replayed, but this time with snapping enabled. This way you can write snapping code directly in your control point's dragged handler as if there was no timeout.

Definition at line 79 of file snap.h.

Member Typedef Documentation

SnapperList

typedef std::list<const Inkscape::Snapper*> SnapManager::SnapperList

Definition at line 97 of file snap.h.

Member Enumeration Documentation

Transformation

enum SnapManager::Transformation

Enumerator
TRANSLATE
SCALE
STRETCH
SKEW
ROTATE

Definition at line 82 of file snap.h.

Constructor & Destructor Documentation

SnapManager()

SnapManager::SnapManager	(	SPNamedView const *	v,
		Inkscape::SnapPreferences &	preferences
	)

Construct a SnapManager for a SPNamedView.

Parameters

v	'Owning' SPNamedView.

Definition at line 51 of file snap.cpp.

References _align_snapper_candidates, and _obj_snapper_candidates.

~SnapManager()

SnapManager::~SnapManager

(

)

Definition at line 67 of file snap.cpp.

References _align_snapper_candidates, and _obj_snapper_candidates.

Member Function Documentation

_findCandidates()

void SnapManager::_findCandidates ( SPObject *  parent, std::vector< SPObject const * > const *  it, Geom::Rect const &  bbox_to_snap, bool const  _clip_or_mask, Geom::Affine const  additional_affine  )

private

Find all items within snapping range.

Parameters

parent	Pointer to the document's root, or to a clipped path or mask object.
it	List of items to ignore.
bbox_to_snap	Bounding box hulling the whole bunch of points, all from the same selection and having the same transformation.
clip_or_mask	The parent object being passed is either a clip or mask.

Definition at line 818 of file snap.cpp.

References _align_snapper_candidates, _findCandidates(), _findCandidates_already_called, _obj_snapper_candidates, Inkscape::LivePathEffect::BOOL_OP, Geom::Parallelogram::bounds(), SPItem::bounds(), Geom::GenericRect< C >::contains(), SPItem::desktopBounds(), SPDesktop::doc2dt(), Geom::GenericRect< C >::expandBy(), SPItem::GEOMETRIC_BBOX, Inkscape::Preferences::get(), SPDesktop::get_display_area(), Inkscape::Preferences::getBool(), SPItem::getCenter(), SPItem::getClipObject(), getDesktop(), SPStyle::getFilter(), SPObject::getId(), SPItem::getMaskObject(), SPItem::i2doc_affine(), Geom::GenericRect< C >::intersects(), Inkscape::SnapPreferences::isTargetSnappable(), item, SPDesktop::itemIsHidden(), parent, snapprefs, Inkscape::SNAPTARGET_BBOX_CATEGORY, Inkscape::SNAPTARGET_PATH_CLIP, Inkscape::SNAPTARGET_PATH_MASK, Inkscape::SNAPTARGET_ROTATION_CENTER, SPObject::style, and SPItem::VISUAL_BBOX.

Referenced by _findCandidates().

constrainedAngularSnap()

Inkscape::SnappedPoint SnapManager::constrainedAngularSnap	(	Inkscape::SnapCandidatePoint const &	p,
		std::optional< Geom::Point > const &	p_ref,
		Geom::Point const &	o,
		unsigned const	snaps
	)		const

Try to snap a point to something at a specific angle.

When drawing a straight line or modifying a gradient, it will snap to specific angle increments if CTRL is being pressed. This method will enforce this angular constraint (even if there is nothing to snap to)

Parameters

p	Source point to be snapped.
p_ref	Optional original point, relative to which the angle should be calculated. If empty then the angle will be calculated relative to the y-axis.
snaps	Number of angular increments per PI radians; E.g. if snaps = 2 then we will snap every PI/2 = 90 degrees.

Definition at line 372 of file snap.cpp.

References Geom::angle_between(), freeSnap(), Inkscape::SnapCandidatePoint::getPoint(), Inkscape::SnappedPoint::getSnapped(), multipleConstrainedSnaps(), Inkscape::SnappedPoint::setTarget(), and Inkscape::SNAPTARGET_CONSTRAINED_ANGLE.

Referenced by Inkscape::UI::Tools::spdc_endpoint_snap_rotation().

constrainedSnap()

Inkscape::SnappedPoint SnapManager::constrainedSnap	(	Inkscape::SnapCandidatePoint const &	p,
		Inkscape::Snapper::SnapConstraint const &	constraint,
		Geom::OptRect const &	bbox_to_snap = Geom::OptRect()
	)		const

Try to snap a point along a constraint line to grids, guides or objects.

Try to snap a point to grids, guides or objects, in only one degree-of-freedom, i.e. snap in a specific direction on the two dimensional canvas to the nearest snap target. constrainedSnap is equal in snapping behavior to constrainedSnapReturnByRef(). Please read the comments of the latter for more details.

PS: SnapManager::setup() must have been called before calling this method, although only once for each set of points PS: If there's nothing to snap to or if snapping has been disabled, then this method will still apply the constraint (but without snapping)

Parameters

p	Source point to be snapped.
constraint	The direction or line along which snapping must occur.
bbox_to_snap	Bounding box hulling the set of points, all from the same selection and having the same transformation.

Definition at line 242 of file snap.cpp.

References _desktop, _objects_to_ignore, _snapindicator, _unselected_nodes, findBestSnap(), freeSnap(), Inkscape::Preferences::get(), Inkscape::Preferences::getBool(), Inkscape::SnapCandidatePoint::getPoint(), SPDesktop::getSnapIndicator(), getSnappers(), Inkscape::SnapCandidatePoint::getSourceNum(), Inkscape::SnapCandidatePoint::getSourceType(), Geom::infinity(), Inkscape::SnapCandidatePoint::isSingleHandle(), Inkscape::Snapper::SnapConstraint::projection(), result, Inkscape::Display::SnapIndicator::set_new_snaptarget(), Inkscape::SNAPTARGET_CONSTRAINT, and someSnapperMightSnap().

Referenced by constrainedSnapReturnByRef(), Inkscape::UI::Handle::dragged(), Inkscape::PureTranslateConstrained::snap(), Inkscape::PureScale::snap(), Inkscape::PureScaleConstrained::snap(), Inkscape::PureStretchConstrained::snap(), Inkscape::PureSkewConstrained::snap(), and Inkscape::PureRotateConstrained::snap().

constrainedSnapReturnByRef()

void SnapManager::constrainedSnapReturnByRef	(	Geom::Point &	p,
		Inkscape::SnapSourceType const	source_type,
		Inkscape::Snapper::SnapConstraint const &	constraint,
		Geom::OptRect const &	bbox_to_snap = Geom::OptRect()
	)		const

Try to snap a point along a constraint line to grids, guides or objects.

Try to snap a point to grids, guides or objects, in only one degree-of-freedom, i.e. snap in a specific direction on the two dimensional canvas to the nearest snap target.

constrainedSnapReturnByRef() is equal in snapping behavior to constrainedSnap(), but the former returns the snapped point through the referenced parameter p. This parameter p initially contains the position of the snap source and will be overwritten by the target position if snapping has occurred. This makes snapping transparent to the calling code. If this is not desired because either the calling code must know whether snapping has occurred, or because the original position should not be touched, then constrainedSnap() should be called instead. If there's nothing to snap to or if snapping has been disabled, then this method will still apply the constraint (but without snapping)

PS: 1) SnapManager::setup() must have been called before calling this method, although only once for each set of points 2) Only to be used when a single source point is to be snapped; it assumes that source_num = 0, which is inefficient when snapping sets our source points

Parameters

p	Current position of the snap source; will be overwritten by the position of the snap target if snapping has occurred.
source_type	Detailed description of the source type, will be used by the snap indicator.
constraint	The direction or line along which snapping must occur.
bbox_to_snap	Bounding box hulling the set of points, all from the same selection and having the same transformation.

Definition at line 233 of file snap.cpp.

References constrainedSnap(), and Inkscape::SnappedPoint::getPoint().

Referenced by Inkscape::UI::Tools::PenTool::_setToNearestHorizVert().

displaySnapsource()

void SnapManager::displaySnapsource

(

Inkscape::SnapCandidatePoint const &

p

)

const

Mark the location of the snap source (not the snap target!) on the canvas by drawing a symbol.

Parameters

point_type	Category of points to which the source point belongs: node, guide or bounding box.
p	The transformed position of the source point, paired with an identifier of the type of the snap source.
point_type	Category of points to which the source point belongs: node, guide or bounding box
p	The transformed position of the source point, paired with an identifier of the type of the snap source.

Definition at line 781 of file snap.cpp.

References _desktop, Inkscape::Preferences::get(), Inkscape::Preferences::getBool(), Inkscape::SnapPreferences::getSnapEnabledGlobally(), SPDesktop::getSnapIndicator(), Inkscape::SnapCandidatePoint::getSourceType(), Inkscape::SnapPreferences::isTargetSnappable(), Inkscape::Display::SnapIndicator::remove_snapsource(), Inkscape::Display::SnapIndicator::set_new_snapsource(), snapprefs, Inkscape::SNAPSOURCE_BBOX_CATEGORY, Inkscape::SNAPSOURCE_DATUMS_CATEGORY, Inkscape::SNAPSOURCE_NODE_CATEGORY, Inkscape::SNAPSOURCE_OTHERS_CATEGORY, Inkscape::SNAPTARGET_BBOX_CATEGORY, and Inkscape::SNAPTARGET_NODE_CATEGORY.

Referenced by Inkscape::SelTrans::getNextClosestPoint(), Inkscape::UI::TransformHandle::getNextClosestPoint(), and snapTransformed().

findBestSnap()

Inkscape::SnappedPoint SnapManager::findBestSnap	(	Inkscape::SnapCandidatePoint const &	p,
		IntermSnapResults const &	isr,
		bool	constrained,
		bool	allowOffScreen = false,
		bool	to_paths_only = false
	)		const

Given a set of possible snap targets, find the best target (which is not necessarily also the nearest target), and show the snap indicator if requested.

Parameters

p	Source point to be snapped.
isr	A structure holding all snap targets that have been found so far.
constrained	True if the snap is constrained, e.g. for stretching or for purely horizontal translation.
allowOffScreen	If true, then snapping to points which are off the screen is allowed (needed for example when pasting to the grid).
to_path_only	Only snap to points on a path, such as path intersections with itself or with grids/guides. This is used for example when adding nodes to a path. We will not snap for example to grid intersections

Returns

An instance of the SnappedPoint class, which holds data on the snap source, snap target, and various metrics.

Definition at line 505 of file snap.cpp.

References _desktop, _snapindicator, Geom::Parallelogram::contains(), IntermSnapResults::curves, SPDesktop::dt2doc(), SPDesktop::get_display_area(), getClosestCurve(), getClosestIntersectionCL(), getClosestIntersectionCS(), getClosestIntersectionSL(), getClosestSL(), getClosestSP(), Inkscape::SnappedPoint::getOnPath(), Inkscape::SnapCandidatePoint::getPoint(), SPDesktop::getSnapIndicator(), Inkscape::SnappedPoint::getSnapped(), Inkscape::SnapCandidatePoint::getSourceType(), IntermSnapResults::grid_lines, IntermSnapResults::guide_lines, Inkscape::SnappedPoint::isOtherSnapBetter(), Inkscape::SnapPreferences::isTargetSnappable(), IntermSnapResults::points, Inkscape::Display::SnapIndicator::remove_snaptarget(), Inkscape::Display::SnapIndicator::set_new_snaptarget(), Inkscape::SnappedPoint::setSource(), Inkscape::SnappedPoint::setTarget(), snapprefs, Inkscape::SNAPTARGET_GRID_GUIDE_INTERSECTION, Inkscape::SNAPTARGET_GRID_INTERSECTION, Inkscape::SNAPTARGET_GRID_LINE, Inkscape::SNAPTARGET_GUIDE_INTERSECTION, Inkscape::SNAPTARGET_PATH, Inkscape::SNAPTARGET_PATH_GUIDE_INTERSECTION, and Inkscape::SNAPTARGET_PATH_INTERSECTION.

Referenced by constrainedSnap(), freeSnap(), guideConstrainedSnap(), guideFreeSnap(), multipleConstrainedSnaps(), and multipleOfGridPitch().

freeSnap()

Inkscape::SnappedPoint SnapManager::freeSnap	(	Inkscape::SnapCandidatePoint const &	p,
		Geom::OptRect const &	bbox_to_snap = Geom::OptRect(),
		bool	to_path_only = false
	)		const

Try to snap a point to grids, guides or objects.

Try to snap a point to grids, guides or objects, in two degrees-of-freedom, i.e. snap in any direction on the two dimensional canvas to the nearest snap target. freeSnap() is equal in snapping behavior to freeSnapReturnByRef(). Please read the comments of the latter for more details

PS: SnapManager::setup() must have been called before calling this method, although only once for each set of points

Parameters

p	Source point to be snapped.
bbox_to_snap	Bounding box hulling the set of points, all from the same selection and having the same transformation.
to_path_only	Only snap to points on a path, such as path intersections with itself or with grids/guides. This is used for example when adding nodes to a path. We will not snap for example to grid intersections

Returns

An instance of the SnappedPoint class, which holds data on the snap source, snap target, and various metrics.

Definition at line 143 of file snap.cpp.

References _objects_to_ignore, _unselected_nodes, findBestSnap(), getSnappers(), Geom::infinity(), Inkscape::SNAPTARGET_UNDEFINED, and someSnapperMightSnap().

Referenced by constrainedAngularSnap(), constrainedSnap(), freeSnapReturnByRef(), Inkscape::UI::Tools::PagesTool::getSnappedResizePoint(), Inkscape::UI::Tools::MeasureTool::knotEndMovedHandler(), Inkscape::UI::Tools::MeasureTool::knotStartMovedHandler(), multipleConstrainedSnaps(), preSnap(), Inkscape::PureTranslate::snap(), Inkscape::PureScale::snap(), and Inkscape::UI::Tools::spdc_endpoint_snap_free().

freeSnapReturnByRef()

void SnapManager::freeSnapReturnByRef	(	Geom::Point &	p,
		Inkscape::SnapSourceType const	source_type,
		Geom::OptRect const &	bbox_to_snap = Geom::OptRect()
	)		const

Try to snap a point to grids, guides or objects.

Try to snap a point to grids, guides or objects, in two degrees-of-freedom, i.e. snap in any direction on the two dimensional canvas to the nearest snap target. freeSnapReturnByRef() is equal in snapping behavior to freeSnap(), but the former returns the snapped point through the referenced parameter p. This parameter p initially contains the position of the snap source and will we overwritten by the target position if snapping has occurred. This makes snapping transparent to the calling code. If this is not desired because either the calling code must know whether snapping has occurred, or because the original position should not be touched, then freeSnap() should be called instead.

PS: 1) SnapManager::setup() must have been called before calling this method, although only once for each set of points 2) Only to be used when a single source point is to be snapped; it assumes that source_num = 0, which is inefficient when snapping sets our source points

Parameters

p	Current position of the snap source; will be overwritten by the position of the snap target if snapping has occurred.
source_type	Detailed description of the source type, will be used by the snap indicator.
bbox_to_snap	Bounding box hulling the set of points, all from the same selection and having the same transformation.

Definition at line 135 of file snap.cpp.

References freeSnap(), Inkscape::SnappedPoint::getPointIfSnapped(), and Inkscape::SNAPTARGET_PATH.

Referenced by Inkscape::UI::Tools::ConnectorTool::_handleButtonPress(), Inkscape::UI::Tools::ConnectorTool::_handleButtonRelease(), Inkscape::UI::Tools::ConnectorTool::_handleMotionNotify(), Inkscape::SelTrans::centerRequest(), Inkscape::UI::Tools::SpiralTool::drag(), Inkscape::UI::Tools::StarTool::drag(), Inkscape::UI::Handle::dragged(), and Inkscape::UI::Tools::MeshTool::root_handler().

getDesktop()

SPDesktop const * SnapManager::getDesktop ( ) const

inline

Definition at line 370 of file snap.h.

References _desktop.

Referenced by _findCandidates(), Inkscape::GridSnapper::get_snap_lines(), Inkscape::GridSnapper::getSnapLinesAxonom(), and Inkscape::GridSnapper::getSnapperTolerance().

getDocument()

SPDocument * SnapManager::getDocument

(

)

const

Definition at line 724 of file snap.cpp.

References _named_view, and SPObject::document.

getGridSnappers()

SnapManager::SnapperList SnapManager::getGridSnappers

(

)

const

Return a list of gridsnappers.

Each grid has its own instance of the snapper class. This way snapping can be enabled per grid individually. A list will be returned containing the pointers to these instances, but only for grids that are being displayed and for which snapping is enabled.

Returns

List of gridsnappers that we use.

Definition at line 87 of file snap.cpp.

References _desktop, _named_view, SPDesktop::getNamedView(), SPNamedView::getShowGrids(), SPNamedView::grids, Inkscape::SnapPreferences::isTargetSnappable(), snapprefs, and Inkscape::SNAPTARGET_GRID.

Referenced by getSnappers(), and gridSnapperMightSnap().

getGuideToIgnore()

SPGuide const * SnapManager::getGuideToIgnore

(

)

const

Definition at line 798 of file snap.cpp.

References _objects_to_ignore, guide, and item.

getNamedView()

SPNamedView const * SnapManager::getNamedView ( ) const

inline

Definition at line 371 of file snap.h.

References _named_view.

Referenced by Inkscape::GridSnapper::_getSnapLines(), Inkscape::UI::Tools::ConnectorTool::_handleButtonPress(), Inkscape::UI::Tools::ConnectorTool::_handleButtonRelease(), Inkscape::UI::Tools::ConnectorTool::_handleMotionNotify(), Inkscape::SelTrans::_keepClosestPointOnly(), Inkscape::SelTrans::centerRequest(), Inkscape::UI::Handle::dragged(), Inkscape::SelTrans::getNextClosestPoint(), Inkscape::SelTrans::grab(), Inkscape::SelTrans::moveTo(), Inkscape::UI::Tools::PagesTool::moveTo(), Inkscape::SelTrans::rotateRequest(), Inkscape::SelTrans::scaleRequest(), Inkscape::SelTrans::skewRequest(), and Inkscape::SelTrans::stretchRequest().

getPageToIgnore()

SPPage const * SnapManager::getPageToIgnore

(

)

const

Definition at line 807 of file snap.cpp.

References _objects_to_ignore, item, and page.

getRotationCenterSource()

const std::vector< SPItem * > & SnapManager::getRotationCenterSource ( )

inline

Definition at line 157 of file snap.h.

References _rotation_center_source_items.

getSnapIndicator()

bool SnapManager::getSnapIndicator ( ) const

inline

Definition at line 376 of file snap.h.

References _snapindicator.

getSnappers()

SnapManager::SnapperList SnapManager::getSnappers

(

)

const

Return a list of snappers.

Inkscape snaps to objects, grids, and guides. For each of these snap targets a separate class is used, which has been derived from the base Snapper class. The getSnappers() method returns a list of pointers to instances of this class. This list contains exactly one instance of the guide snapper and of the object snapper class, but any number of grid snappers (because each grid has its own snapper instance)

Returns

List of snappers that we use.

Definition at line 73 of file snap.cpp.

References alignment, distribution, getGridSnappers(), gs, and guide.

Referenced by constrainedSnap(), freeSnap(), guideConstrainedSnap(), guideFreeSnap(), multipleConstrainedSnaps(), and someSnapperMightSnap().

gridSnapperMightSnap()

bool SnapManager::gridSnapperMightSnap

(

)

const

Returns

true if one of the grids might be snapped to.

Definition at line 120 of file snap.cpp.

References getGridSnappers(), Inkscape::SnapPreferences::getSnapEnabledGlobally(), Inkscape::SnapPreferences::getSnapPostponedGlobally(), and snapprefs.

guideConstrainedSnap()

void SnapManager::guideConstrainedSnap	(	Geom::Point &	p,
		SPGuide const &	guideline
	)		const

Wrapper method to make snapping of the guide origin a bit easier (i.e.

simplifies the calling code).

PS: SnapManager::setup() must have been called before calling this method,

Parameters

p	Current position of the point on the guide that is to be snapped; will be overwritten by the position of the snap target if snapping has occurred.
guideline	The guide that is currently being dragged

Definition at line 445 of file snap.cpp.

References findBestSnap(), SPGuide::getNormal(), SPGuide::getPoint(), Inkscape::SnappedPoint::getPointIfSnapped(), Inkscape::SnapPreferences::getSnapEnabledGlobally(), getSnappers(), Inkscape::SnapPreferences::getSnapPostponedGlobally(), Inkscape::SnapPreferences::isTargetSnappable(), Geom::rot90(), snapprefs, Inkscape::SNAPSOURCE_GUIDE_ORIGIN, Inkscape::SNAPTARGET_GUIDE, and Inkscape::SNAPTARGET_UNDEFINED.

guideFreeSnap()

void SnapManager::guideFreeSnap	(	Geom::Point &	p,
		Geom::Point &	origin_or_vector,
		bool	origin,
		bool	freeze_angle
	)		const

Wrapper method to make snapping of the guide origin a bit easier (i.e.

simplifies the calling code).

PS: SnapManager::setup() must have been called before calling this method,

Parameters

p	Current position of the point on the guide that is to be snapped; will be overwritten by the position of the snap target if snapping has occurred.
origin_or_vector	Data used for tangential and perpendicular snapping. When rotating a guide the origin of the rotation is specified here, whereas when dragging a guide its vector is specified here
origin	If true then origin_or_vector contains an origin, other it contains a vector
freeze_angle	If true (in which case origin is false), then the vector specified in origin_or_vector will not be touched, i.e. the guide will in all circumstances keep its angle. Otherwise the vector in origin_or_vector can be updated, meaning that the guide might take on the angle of a curve that has been snapped too tangentially or perpendicularly

Definition at line 408 of file snap.cpp.

References Inkscape::SnapCandidatePoint::addOrigin(), Inkscape::SnapCandidatePoint::addVector(), Geom::are_near(), findBestSnap(), Inkscape::SnappedPoint::getPointIfSnapped(), Inkscape::SnapPreferences::getSnapEnabledGlobally(), Inkscape::SnappedPoint::getSnapped(), getSnappers(), Inkscape::SnapPreferences::getSnapPostponedGlobally(), Inkscape::SnappedPoint::getTangent(), Inkscape::SnapPreferences::isTargetSnappable(), origin, Geom::rot90(), snapprefs, Inkscape::SNAPSOURCE_GUIDE, Inkscape::SNAPSOURCE_GUIDE_ORIGIN, and Inkscape::SNAPTARGET_GUIDE.

multipleConstrainedSnaps()

Inkscape::SnappedPoint SnapManager::multipleConstrainedSnaps	(	Inkscape::SnapCandidatePoint const &	p,
		std::vector< Inkscape::Snapper::SnapConstraint > const &	constraints,
		bool	dont_snap = false,
		Geom::OptRect const &	bbox_to_snap = Geom::OptRect()
	)		const

Definition at line 306 of file snap.cpp.

References _objects_to_ignore, _unselected_nodes, c, findBestSnap(), freeSnap(), Inkscape::Preferences::get(), Inkscape::Preferences::getBool(), Inkscape::SnapCandidatePoint::getPoint(), Inkscape::SnappedPoint::getPoint(), getSnappers(), Inkscape::SnapCandidatePoint::getSourceNum(), Inkscape::SnapCandidatePoint::getSourceType(), Geom::infinity(), Inkscape::SnapCandidatePoint::isSingleHandle(), Geom::L2(), Inkscape::Snapper::SnapConstraint::projection(), result, Inkscape::SnappedPoint::setPoint(), Inkscape::SNAPTARGET_CONSTRAINT, and someSnapperMightSnap().

Referenced by Inkscape::SelTrans::centerRequest(), and constrainedAngularSnap().

multipleOfGridPitch()

Geom::Point SnapManager::multipleOfGridPitch	(	Geom::Point const &	t,
		Geom::Point const &	origin
	)

Snap to the closest multiple of a grid pitch.

When pasting, we would like to snap to the grid. Problem is that we don't know which nodes were aligned to the grid at the time of copying, so we don't know which nodes to snap. If we'd snap an unaligned node to the grid, previously aligned nodes would become unaligned. That's undesirable. Instead we will make sure that the offset between the source and its pasted copy is a multiple of the grid pitch. If the source was aligned, then the copy will therefore also be aligned.

PS: Whether we really find a multiple also depends on the snapping range! Most users will have "always snap" enabled though, in which case a multiple will always be found. PS2: When multiple grids are present then the result will become ambiguous. There is no way to control to which grid this method will snap.

Parameters

t	Vector that represents the offset of the pasted copy with respect to the original.

Returns

Offset vector after snapping to the closest multiple of a grid pitch.

Definition at line 178 of file snap.cpp.

References _desktop, _named_view, _snapindicator, findBestSnap(), Inkscape::Snapper::freeSnap(), SPDesktop::getNamedView(), Inkscape::SnappedPoint::getPoint(), SPNamedView::getShowGrids(), Inkscape::SnappedPoint::getSnapDistance(), Inkscape::SnapPreferences::getSnapEnabledGlobally(), SPDesktop::getSnapIndicator(), Inkscape::SnappedPoint::getSnapped(), Inkscape::SnapPreferences::getSnapPostponedGlobally(), SPNamedView::grids, Geom::infinity(), origin, Inkscape::Display::SnapIndicator::set_new_snaptarget(), Inkscape::SnappedPoint::setPoint(), snapprefs, Inkscape::SNAPSOURCE_GRID_PITCH, and Inkscape::Snapper::ThisSnapperMightSnap().

Referenced by Inkscape::SelTrans::moveTo().

preSnap()

void SnapManager::preSnap	(	Inkscape::SnapCandidatePoint const &	p,
		bool	to_path_only = false
	)

Definition at line 161 of file snap.cpp.

References _desktop, _snapindicator, freeSnap(), SPDesktop::getSnapIndicator(), Inkscape::SnappedPoint::getSnapped(), Inkscape::Display::SnapIndicator::remove_snaptarget(), and Inkscape::Display::SnapIndicator::set_new_snaptarget().

Referenced by Inkscape::UI::Tools::PenTool::_handleMotionNotify(), Inkscape::UI::Tools::PencilTool::_handleMotionNotify(), and Inkscape::UI::Tools::ConnectorTool::_handleMotionNotify().

setRotationCenterSource()

void SnapManager::setRotationCenterSource ( const std::vector< SPItem * > &  items )

inline

Definition at line 156 of file snap.h.

References _rotation_center_source_items, and items.

Referenced by Inkscape::SelTrans::centerRequest().

setup() [1/2]

void SnapManager::setup	(	SPDesktop const *	desktop,
		bool	snapindicator,
		std::vector< SPObject const * > &	objects_to_ignore,
		std::vector< Inkscape::SnapCandidatePoint > *	unselected_nodes = nullptr
	)

Prepare the snap manager for the actual snapping, which includes building a list of snap targets to ignore and toggling the snap indicator.

There are two overloaded setup() methods, of which the other one only allows for a single item to be ignored whereas this one will take a list of items to ignore

Parameters

desktop	Reference to the desktop to which this snap manager is attached.
snapindicator	If true then a snap indicator will be displayed automatically (when enabled in the preferences).
objects_to_ignore	These items will not be snapped to, e.g. the items that are currently being dragged. This avoids "self-snapping" this includes guides and other non-items.
unselected_nodes	Stationary nodes of the path that is currently being edited in the node tool and that can be snapped too. Nodes not in this list will not be snapped to, to avoid "self-snapping". Of each unselected node both the position (Geom::Point) and the type (Inkscape::SnapTargetType) will be stored.

Definition at line 683 of file snap.cpp.

References _desktop, _findCandidates_already_called, _objects_to_ignore, _rotation_center_source_items, _snapindicator, _unselected_nodes, and desktop.

setup() [2/2]

void SnapManager::setup	(	SPDesktop const *	desktop,
		bool	snapindicator = true,
		SPObject const *	item_to_ignore = nullptr,
		std::vector< Inkscape::SnapCandidatePoint > *	unselected_nodes = nullptr
	)

Convenience shortcut when there is only one item to ignore.

Definition at line 663 of file snap.cpp.

References _desktop, _findCandidates_already_called, _objects_to_ignore, _rotation_center_source_items, _snapindicator, _unselected_nodes, and desktop.

Referenced by Inkscape::UI::Tools::ConnectorTool::_handleButtonPress(), Inkscape::UI::Tools::PenTool::_handleButtonPress(), Inkscape::UI::Tools::PencilTool::_handleButtonPress(), Inkscape::UI::Tools::ConnectorTool::_handleButtonRelease(), Inkscape::UI::Tools::PenTool::_handleMotionNotify(), Inkscape::UI::Tools::PencilTool::_handleMotionNotify(), Inkscape::UI::Tools::ConnectorTool::_handleMotionNotify(), Inkscape::UI::Tools::PenTool::_setToNearestHorizVert(), Inkscape::UI::PathManipulator::_updateDragPoint(), Inkscape::SelTrans::centerRequest(), Inkscape::UI::Tools::SpiralTool::drag(), Inkscape::UI::Tools::StarTool::drag(), Inkscape::UI::Node::dragged(), Inkscape::SelTrans::getNextClosestPoint(), Inkscape::UI::TransformHandle::getNextClosestPoint(), Inkscape::UI::Tools::PagesTool::getSnappedResizePoint(), gr_knot_moved_midpoint_handler(), Inkscape::UI::Tools::MeasureTool::knotEndMovedHandler(), Inkscape::UI::Tools::MeasureTool::knotStartMovedHandler(), Inkscape::SelTrans::moveTo(), Inkscape::UI::Tools::PagesTool::moveTo(), Inkscape::UI::Tools::ArcTool::root_handler(), Inkscape::UI::Tools::Box3dTool::root_handler(), Inkscape::UI::Tools::MeasureTool::root_handler(), Inkscape::UI::Tools::MeshTool::root_handler(), Inkscape::UI::Tools::NodeTool::root_handler(), Inkscape::UI::Tools::RectTool::root_handler(), Inkscape::UI::Tools::SpiralTool::root_handler(), Inkscape::UI::Tools::StarTool::root_handler(), Inkscape::UI::Tools::TextTool::root_handler(), Inkscape::SelTrans::rotateRequest(), Inkscape::UI::Widget::ruler_snap_new_guide(), Inkscape::SelTrans::scaleRequest(), Inkscape::SelTrans::skewRequest(), KnotHolderEntity::snap_knot_position(), KnotHolderEntity::snap_knot_position_constrained(), Inkscape::snap_rectangular_box(), sp_dt_guide_event(), sp_import_document(), Inkscape::UI::Tools::spdc_endpoint_snap_free(), Inkscape::UI::Tools::spdc_endpoint_snap_rotation(), Inkscape::SelTrans::stretchRequest(), and Box3D::vp_knot_moved_handler().

setupIgnoreSelection()

void SnapManager::setupIgnoreSelection	(	SPDesktop const *	desktop,
		bool	snapindicator = true,
		std::vector< Inkscape::SnapCandidatePoint > *	unselected_nodes = nullptr
	)

Setup, taking the list of items to ignore from the desktop's selection.

Definition at line 701 of file snap.cpp.

References _desktop, _findCandidates_already_called, _objects_to_ignore, _rotation_center_source_items, _snapindicator, _unselected_nodes, desktop, SPDesktop::getSelection(), items, and Inkscape::ObjectSet::items().

Referenced by Inkscape::UI::Handle::dragged().

snapTransformed()

void SnapManager::snapTransformed	(	std::vector< Inkscape::SnapCandidatePoint > const &	points,
		Geom::Point const &	pointer,
		Inkscape::PureTransform &	transform
	)

Method for snapping sets of points while they are being transformed.

Method for snapping sets of points while they are being transformed, when using for example the selector tool.

This is what is being done in this method: transform each point, find out whether a free snap or constrained snap is more appropriate, do the snapping, calculate some metrics to quantify the snap "distance", and see if it's better than the previous snap. Finally, the best ("nearest") snap from all these points is returned. If no snap has occurred and we're asked for a constrained snap then the constraint will be applied nevertheless

Parameters

points	Collection of points to snap (snap sources), at their untransformed position, all points undergoing the same transformation. Paired with an identifier of the type of the snap source.
pointer	Location of the mouse pointer at the time dragging started (i.e. when the selection was still untransformed).
transform	Describes the type of transformation, it's parameters, and any additional constraints

Definition at line 465 of file snap.cpp.

References _desktop, _snapindicator, Inkscape::PureTransform::best_snapped_point, displaySnapsource(), Inkscape::SnappedPoint::getPoint(), SPDesktop::getSnapIndicator(), Inkscape::SnappedPoint::getSnapped(), Inkscape::Display::SnapIndicator::remove_snaptarget(), Inkscape::Display::SnapIndicator::set_new_snaptarget(), and Inkscape::PureTransform::snap().

Referenced by Inkscape::SelTrans::moveTo(), Inkscape::UI::Tools::PagesTool::moveTo(), Inkscape::SelTrans::rotateRequest(), Inkscape::SelTrans::scaleRequest(), Inkscape::SelTrans::skewRequest(), and Inkscape::SelTrans::stretchRequest().

someSnapperMightSnap()

bool SnapManager::someSnapperMightSnap

(

bool

immediately = true

)

const

Return true if any snapping might occur, whether its to grids, guides or objects.

Each snapper instance handles its own snapping target, e.g. grids, guides or objects. This method iterates through all these snapper instances and returns true if any of the snappers might possible snap, considering only the relevant snapping preferences.

Returns

true if one of the snappers will try to snap to something.

Definition at line 100 of file snap.cpp.

References Inkscape::SnapPreferences::getSnapEnabledGlobally(), getSnappers(), Inkscape::SnapPreferences::getSnapPostponedGlobally(), and snapprefs.

Referenced by constrainedSnap(), Inkscape::UI::Handle::dragged(), freeSnap(), Inkscape::SelTrans::grab(), and multipleConstrainedSnaps().

unSetup()

void SnapManager::unSetup ( )

inline

Definition at line 147 of file snap.h.

References _desktop, _objects_to_ignore, _rotation_center_source_items, and _unselected_nodes.

Referenced by Inkscape::UI::Tools::ConnectorTool::_handleButtonPress(), Inkscape::UI::Tools::ConnectorTool::_handleButtonRelease(), Inkscape::UI::Tools::PenTool::_handleMotionNotify(), Inkscape::UI::Tools::PencilTool::_handleMotionNotify(), Inkscape::UI::Tools::ConnectorTool::_handleMotionNotify(), Inkscape::UI::Tools::PenTool::_setToNearestHorizVert(), Inkscape::SelTrans::centerRequest(), Inkscape::UI::Tools::SpiralTool::drag(), Inkscape::UI::Tools::StarTool::drag(), Inkscape::UI::Handle::dragged(), Inkscape::SelTrans::getNextClosestPoint(), Inkscape::UI::TransformHandle::getNextClosestPoint(), Inkscape::UI::Tools::PagesTool::getSnappedResizePoint(), Inkscape::UI::Tools::MeasureTool::knotEndMovedHandler(), Inkscape::UI::Tools::MeasureTool::knotStartMovedHandler(), Inkscape::SelTrans::moveTo(), Inkscape::UI::Tools::PagesTool::moveTo(), Inkscape::UI::Tools::MeshTool::root_handler(), Inkscape::SelTrans::rotateRequest(), Inkscape::SelTrans::scaleRequest(), Inkscape::SelTrans::skewRequest(), Inkscape::UI::Tools::spdc_endpoint_snap_free(), Inkscape::UI::Tools::spdc_endpoint_snap_rotation(), and Inkscape::SelTrans::stretchRequest().

Friends And Related Symbol Documentation

Inkscape::AlignmentSnapper

friend class Inkscape::AlignmentSnapper

friend

Definition at line 449 of file snap.h.

Inkscape::DistributionSnapper

friend class Inkscape::DistributionSnapper

friend

Definition at line 450 of file snap.h.

Inkscape::ObjectSnapper

friend class Inkscape::ObjectSnapper

friend

Definition at line 448 of file snap.h.

Member Data Documentation

_align_snapper_candidates

std::unique_ptr<std::vector<Inkscape::SnapCandidateItem> > SnapManager::_align_snapper_candidates

private

Definition at line 446 of file snap.h.

Referenced by _findCandidates(), SnapManager(), and ~SnapManager().

_desktop

SPDesktop const* SnapManager::_desktop

private

Definition at line 427 of file snap.h.

Referenced by constrainedSnap(), displaySnapsource(), findBestSnap(), getDesktop(), getGridSnappers(), multipleOfGridPitch(), preSnap(), setup(), setup(), setupIgnoreSelection(), snapTransformed(), and unSetup().

_findCandidates_already_called

bool SnapManager::_findCandidates_already_called

private

Definition at line 443 of file snap.h.

Referenced by _findCandidates(), setup(), setup(), and setupIgnoreSelection().

_named_view

SPNamedView const* SnapManager::_named_view

protected

Definition at line 422 of file snap.h.

Referenced by getDocument(), getGridSnappers(), getNamedView(), and multipleOfGridPitch().

_obj_snapper_candidates

std::unique_ptr<std::vector<Inkscape::SnapCandidateItem> > SnapManager::_obj_snapper_candidates

private

Definition at line 445 of file snap.h.

Referenced by _findCandidates(), SnapManager(), and ~SnapManager().

_objects_to_ignore

std::vector<SPObject const *> SnapManager::_objects_to_ignore

private

Items that should not be snapped to, for example the items that are currently being dragged. Set using the setup() method.

Definition at line 425 of file snap.h.

Referenced by constrainedSnap(), freeSnap(), getGuideToIgnore(), getPageToIgnore(), multipleConstrainedSnaps(), setup(), setup(), setupIgnoreSelection(), and unSetup().

_rotation_center_source_items

std::vector<SPItem*> SnapManager::_rotation_center_source_items

private

Definition at line 426 of file snap.h.

Referenced by getRotationCenterSource(), setRotationCenterSource(), setup(), setup(), setupIgnoreSelection(), and unSetup().

_snapindicator

bool SnapManager::_snapindicator

private

When true, an indicator will be drawn at the position that was being snapped to.

Definition at line 428 of file snap.h.

Referenced by constrainedSnap(), findBestSnap(), getSnapIndicator(), multipleOfGridPitch(), preSnap(), setup(), setup(), setupIgnoreSelection(), and snapTransformed().

_unselected_nodes

std::vector<Inkscape::SnapCandidatePoint>* SnapManager::_unselected_nodes

private

Nodes of the path that is currently being edited and which have not been selected and which will therefore be stationary. Only these nodes will be considered for snapping to. Of each unselected node both the position (Geom::Point) and the type (Inkscape::SnapTargetType) will be stored.

Definition at line 429 of file snap.h.

Referenced by constrainedSnap(), freeSnap(), multipleConstrainedSnaps(), setup(), setup(), setupIgnoreSelection(), and unSetup().

alignment

Inkscape::AlignmentSnapper SnapManager::alignment

snapper to align with other objects

Definition at line 340 of file snap.h.

Referenced by getSnappers().

distribution

Inkscape::DistributionSnapper SnapManager::distribution

Definition at line 341 of file snap.h.

Referenced by getSnappers().

guide

Inkscape::GuideSnapper SnapManager::guide

guide snapper

Definition at line 338 of file snap.h.

Referenced by getGuideToIgnore(), and getSnappers().

object

Inkscape::ObjectSnapper SnapManager::object

snapper to other objects

Definition at line 339 of file snap.h.

snapprefs

Inkscape::SnapPreferences& SnapManager::snapprefs

Definition at line 342 of file snap.h.

Referenced by _findCandidates(), Inkscape::SelTrans::_keepClosestPointOnly(), displaySnapsource(), findBestSnap(), getGridSnappers(), Inkscape::GridSnapper::getSnapperTolerance(), gr_knot_moved_handler(), Inkscape::SelTrans::grab(), gridSnapperMightSnap(), guideConstrainedSnap(), guideFreeSnap(), Inkscape::UI::Tools::PagesTool::moveTo(), multipleOfGridPitch(), SPNamedView::set(), someSnapperMightSnap(), Inkscape::UI::Tools::spdc_endpoint_snap_rotation(), and Inkscape::GridSnapper::ThisSnapperMightSnap().

---

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

• /builds/inkscape/inkscape/src/snap.h
• /builds/inkscape/inkscape/src/snap.cpp