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107 lines
4.0 KiB
C
107 lines
4.0 KiB
C
3 weeks ago
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/*=========================================================================
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Program: Visualization Toolkit
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Module: vtkSpanTreeLayoutStrategy.h
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Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
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All rights reserved.
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See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
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This software is distributed WITHOUT ANY WARRANTY; without even
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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PURPOSE. See the above copyright notice for more information.
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=========================================================================*/
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//-------------------------------------------------------------------------
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// Copyright 2008 Sandia Corporation.
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// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
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// the U.S. Government retains certain rights in this software.
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//-------------------------------------------------------------------------
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/**
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* @class vtkSpanTreeLayoutStrategy
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*
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* vtkSpanTreeLayout is a strategy for drawing directed graphs that
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* works by first extracting a spanning tree (more accurately, a
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* spanning forest), and using this both to position graph vertices
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* and to plan the placement of non-tree edges. The latter are drawn
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* with the aid of edge points to produce a tidy drawing.
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*
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* The approach is best suited to "quasi-trees", graphs where the number
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* of edges is of the same order as the number of nodes; it is less well
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* suited to denser graphs. The boolean flag DepthFirstSpanningTree
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* determines whether a depth-first or breadth-first strategy is used to
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* construct the underlying forest, and the choice of strategy affects
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* the output layout significantly. Informal experiments suggest that
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* the breadth-first strategy is better for denser graphs.
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*
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* Different layouts could also be produced by plugging in alternative
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* tree layout strategies. To work with the method of routing non-tree
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* edges, any strategy should draw a tree so that levels are equally
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* spaced along the z-axis, precluding for example the use of a radial
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* or balloon layout.
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*
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* vtkSpanTreeLayout is based on an approach to 3D graph layout first
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* developed as part of the "tulip" tool by Dr. David Auber at LaBRI,
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* U.Bordeaux: see www.tulip-software.org
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*
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* This implementation departs from the original version in that:
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* (a) it is reconstructed to use Titan/VTK data structures;
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* (b) it uses a faster method for dealing with non-tree edges,
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* requiring at most two edge points per edge
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* (c) allows for plugging in different tree layout methods
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* (d) allows selection of two different strategies for building
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* the underlying layout tree, which can yield significantly
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* different results depending on the data.
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*
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* @par Thanks:
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* Thanks to David Duke from the University of Leeds for providing this
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* implementation.
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*/
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#ifndef vtkSpanTreeLayoutStrategy_h
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#define vtkSpanTreeLayoutStrategy_h
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#include "vtkGraphLayoutStrategy.h"
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#include "vtkInfovisLayoutModule.h" // For export macro
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class VTKINFOVISLAYOUT_EXPORT vtkSpanTreeLayoutStrategy : public vtkGraphLayoutStrategy
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{
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public:
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static vtkSpanTreeLayoutStrategy* New();
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vtkTypeMacro(vtkSpanTreeLayoutStrategy, vtkGraphLayoutStrategy);
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void PrintSelf(ostream& os, vtkIndent indent) override;
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//@{
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/**
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* If set, base the layout on a depth-first spanning tree,
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* rather than the default breadth-first spanning tree.
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* Switching between DFT and BFT may significantly change
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* the layout, and choice must be made on a per-graph basis.
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* Default value is off.
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*/
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vtkSetMacro(DepthFirstSpanningTree, bool);
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vtkGetMacro(DepthFirstSpanningTree, bool);
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vtkBooleanMacro(DepthFirstSpanningTree, bool);
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//@}
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/**
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* Perform the layout.
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*/
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void Layout() override;
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protected:
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vtkSpanTreeLayoutStrategy();
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~vtkSpanTreeLayoutStrategy() override;
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vtkGraphLayoutStrategy* TreeLayout;
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bool DepthFirstSpanningTree;
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private:
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vtkSpanTreeLayoutStrategy(const vtkSpanTreeLayoutStrategy&) = delete;
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void operator=(const vtkSpanTreeLayoutStrategy&) = delete;
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};
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#endif
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