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java.lang.Object y.layout.AbstractLayoutStage y.layout.CurveFittingLayoutStage
public class CurveFittingLayoutStage
CurveFittingLayoutStage
fits a piecewise cubic bezier curve to given arbitrary edge paths.
The path
of an edge, i.e., its start and end point as well as the
intermediate control points, are interpreted as the set of input points. A cubic bezier curve is
then fitted to these points.
After the fitting, the points of the processed edges can be interpreted as cubic bezier control points. Each four consecutive points form a bezier curve, where the first and last of the four points represent the start and end of the curve and the second and third point are the control points defining how the curve looks. The second and third point do not necessarily lie on the actual curve.
There are two exceptions to the stated rules:
The maximum allowed error
for the fitting process can be selected to control
how high the precision should be. A high allowed error means that the approximation process has a lot
of freedom. Curves are only loosely bound to the original edge path. If this is not desired, e.g., because
no new intersection with other graph elements should be introduced, then a rather low error value should be
specified. The lower the error value, the larger the number of bend points of an approximated edge will be.
It is possible to define the set of edges that should be processed by this layout stage. Therefore, only
paths of a subset of edges can be changed. Use a DataProvider
registered with the specified
selection key
to mark edges which should be part of the
considered subset.
CurveFittingLayoutStage
is useful if curved edge paths were
modeled using a large number of bends which are then connected by straight lines  as, for example,
produced by RadialLayouter
. Applying this stage can drastically
reduce the number of necessary bends in such cases.Field Summary  

static java.lang.Object 
FITTING_SELECTION_DPKEY
A DataProvider key for selecting edges for curve fitting

Fields inherited from interface y.layout.Layouter 

EDGE_ID_DPKEY, NODE_ID_DPKEY, SELECTED_EDGES, SELECTED_NODES 
Constructor Summary  

CurveFittingLayoutStage()
Creates a new CurveFittingLayoutStage with default settings. 

CurveFittingLayoutStage(Layouter core)
Creates a new CurveFittingLayoutStage with the given algorithm as core layout algorithm . 
Method Summary  

boolean 
canLayout(LayoutGraph graph)
Accepts all graphs that can be handled by the core layout algorithm . 
void 
doLayout(LayoutGraph graph)
Changes the edge paths of selected edges of the given graph such that they represent piecewise cubic bezier curves which approximate the original points of the path. 
double 
getMaximumError()
Returns the maximum allowed error for the fitting process. 
java.lang.Object 
getSelectedEdgesDpKey()
Returns the DataProvider key to look up the selection state of the edges that defines whether
or not an edge's path should be approximated by a bezier curve. 
double 
getStraightControlPointRatio()
Returns the ratio that defines the distance between the intermediate control points and the end points of a cubic segment which actually represents a straight line, i.e., in case the four points are collinear. 
void 
setMaximumError(double maximumError)
Specifies the maximum allowed error for the fitting process. 
void 
setSelectedEdgesDpKey(java.lang.Object selectedEdgesDpKey)
Specifies the DataProvider key to look up the selection state of the edges that defines whether
or not an edge's path should be approximated by a bezier curve. 
void 
setStraightControlPointRatio(double straightControlPointRatio)
Specifies the ratio that defines the distance between the intermediate control points and the end points of a cubic segment which actually represents a straight line, i.e., in case the four points are collinear. 
Methods inherited from class y.layout.AbstractLayoutStage 

canLayoutCore, doLayoutCore, getCoreLayouter, setCoreLayouter 
Methods inherited from class java.lang.Object 

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Field Detail 

public static final java.lang.Object FITTING_SELECTION_DPKEY
DataProvider
key for selecting edges for curve fitting
DataProvider
registered with this key, a curve is fitted to all edges.Constructor Detail 

public CurveFittingLayoutStage()
CurveFittingLayoutStage
with default settings.
public CurveFittingLayoutStage(Layouter core)
CurveFittingLayoutStage
with the given algorithm as core layout algorithm
.
core
 the core layout algorithmMethod Detail 

public double getMaximumError()
The error is defined as the minimum distance between an original input control point (i.e. bend) of and edge and the fitted bezier curve.
The maximum error must be greater than or equal to zero.
setMaximumError(double)
public void setMaximumError(double maximumError)
The error is defined as the minimum distance between an original input control point (i.e. bend) of and edge and the fitted bezier curve.
The maximum error must be greater than or equal to zero.
maximumError
 the maximum allowed error for the fitting process
java.lang.IllegalArgumentException
 if the specified maximum error is negativepublic double getStraightControlPointRatio()
0.33
 the second and third control point are equally distributed between
te first and fourth point.
0.0
 the first and second control point as well as the
third and fourth point are equal.
0.5
 the second and third control point are equal and exactly the midpoint
between the first and fourth point.
The control point ratio is defined to be within the interval [0.0, 0.5]
.
setStraightControlPointRatio(double)
public void setStraightControlPointRatio(double straightControlPointRatio)
0.33
 the second and third control point are equally distributed between
te first and fourth point.
0.0
 the first and second control point as well as the
third and fourth point are equal.
0.5
 the second and third control point are equal and exactly the midpoint
between the first and fourth point.
The control point ratio is defined to be within the interval [0.0, 0.5]
.
straightControlPointRatio
 the control point ratio for straightline path segments
java.lang.IllegalArgumentException
 if the specified ratio is outside the interval [0.0, 0.5]
public java.lang.Object getSelectedEdgesDpKey()
DataProvider
key to look up the selection state of the edges that defines whether
or not an edge's path should be approximated by a bezier curve.
If there is a DataProvider
registered with the input graph with this key, then only marked edges are
processed by this layout stage. Otherwise, all edges are processed.
DataProvider
key for edge selectionsetSelectedEdgesDpKey(Object)
public void setSelectedEdgesDpKey(java.lang.Object selectedEdgesDpKey)
DataProvider
key to look up the selection state of the edges that defines whether
or not an edge's path should be approximated by a bezier curve.
If there is a DataProvider
registered with the input graph with this key, then only marked edges are
processed by this layout stage. Otherwise, all edges are processed.
FITTING_SELECTION_DPKEY
selectedEdgesDpKey
 the DataProvider
key for edge selection
java.lang.IllegalArgumentException
 if the specified DataProvider
key is null
public boolean canLayout(LayoutGraph graph)
core layout algorithm
.
If there is no core layout algorithm
, all graphs are accepted.
graph
 the input graph
true
if there is no core layout algorithm or the core layout algorithm accepts the graph,
false
otherwiseLayouter.doLayout(LayoutGraph)
public void doLayout(LayoutGraph graph)
graph
 the input graphLayouter.canLayout(LayoutGraph)

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