5 Graph Description Language (GDL) - Absint

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5.16 Animations aiSee employs two different animation concepts. First, some internal layout calculations can be animated under the control of some options. Second, the entire aiSee tool can be used as an animation handler which animates a sequence of graph specifications. (Note that this has nothing to do with the -multi option.) 5.16.1 Animation of layout phases (aka smooth transitions) If a new layout is calculated for a graph and if animation of layout phases is turned on, the nodes move smoothly from their initial positions in the layout to the newly calculated ones, enabling the user to keep visual track of layout changes. The GDL graph attribute amax: specifies the maximum number of animation steps. This number can be changed interactively in the View dialog box. Specifying 0 means animation is turned off. 5.16.2 Animating graph specification sequences aiSee can be used as an animation handler to animate a sequence of graph specifications. A program can continuously output GDL specifications to a file. When the program has produced one instance of output, it informs aiSee that the graph specification is available. Then aiSee displays the new instance of the graph. After visualization, aiSee indicates completion to the program generating the graph specifications, thus enabling the program to output the next graph specification. Consequently, the program and aiSee represent a client-server model. The program calls aiSee with the option -a (see p. 133). After relayout aiSee sleeps seconds, then it attempts a callback to the parent process. aiSee has to have been started with the option -ddemsg option. Then the program and aiSee communicate with one another via a DDE channel as a server and client. For further information about using aiSee as an animation handler, please contact aiSee@AbsInt.com. 114
6 Overview of the Layout Phases The task of aiSee is to parse a graph specification, calculate a layout according to the layout algorithm chosen, and draw the resulting layout in a window. The specification given as input to aiSee is a readable ASCII text. The output window can be used to browse through the graph, shrink or magnify the graph, fold parts of the graph, and export the graph to a bitmap or PostScript file. Graph folding potentially results in a new layout of the graph. The layout can be extensively influenced by edge, node and graph attributes or by different layout algorithms. aiSee offers forcedirected and hierarchical layout schemes. 6.1 Parsing The first phase is to parse the specification and construct internal data structures representing the graph. The specification may contain attributes denoting initially folded parts of the graph. 6.2 Grouping of Nodes and Edges – Folding Phase aiSee offers various ways of grouping nodes and edges (see p. 24). Folding a graph enables the graph to be inspected in a more efficient manner. Folding the unimportant parts gives the more important parts more space for visualization. Folding parts of the graph also improves aiSee’s performance. It should be noted that nested foldings are possible. In graph specifications, the folding of regions or subgraphs may interfere with the hiding of edges. In this case, first the summary node of the folded region or subgraph is calculated, followed by hiding the edges. 6.3 Force-Directed Layout Force-directed layout schemes are usually selected for undirected graphs, this being ideal for simulating physical and chemical models. aiSee combines the following four ideas in its force-directed layout algorithm: • Spring forces A spring embedder is simulated. The nodes of a graph are regarded as electrically charged particles that repel one another, the edges being regarded as springs connecting the particles. Particles that are far away from one another attract each another by spring forces, particles that are too close repel one another. • Magnetic forces Spring forces do not take the direction of edges into account. In directed graphs all edges should have a uniform direction to point in. Here the edges are interpreted as magnetic needles that align themselves according to a magnetic field. 115
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aiSee Graph Visualization User Docu
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3.6 Auxiliaries (User Action) . . .
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6.4.1 Rank Assignment . . . . . . .
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1 Introduction aiSee is a tool that
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3 Usage This chapter describes the
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3.3 Navigating Through a Graph Ther
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• Information field 1, 2, or 3 Th
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focus. The entire graph is drawn in
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• Clicking in an open information
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There is no direct interface for pr
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• Center width centers horizontal
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4.1.3 Example Figure 7 shows a nest
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4.1.4 Edge Classes - Expose/Hide Ed
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Operations: A neighbor region can b
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Note: Clustering is an experimental
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Figure 9: View Dialog Box • Scrol
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Figure 11: Polar Fish-Eye View Self
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for a graph and if animation is tur
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• Arrow Heads Enables the mode fo
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B in the message window (see p. 120
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} < list of node attributes > The t
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} target: < title of target node >
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5.6 Examples of GDL Specifications
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Figure 14: Bent Near, Right-Bent Ne
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06 yspace: 55 07 node: { title:"18"
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22 node: { title:"2" label: "Start"
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11 edge: { source: "0" target: "4"
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Figure 21: Example 10, maxdepth; an
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• maxoutdegree, finetuning: no Th
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Figure 27: Example 11, tree layout,
Page 63 and 64: the style of edges in order to redu
Page 65 and 66: 63 node: { title: "tcsh" level: 6 s
Page 67 and 68: • bmax Type: integer Default valu
Page 69 and 70: specifies the color white. For inst
Page 71 and 72: - energetic gravity, Default value:
Page 73 and 74: This attribute specifies the consta
Page 75 and 76: Attribute of: subgraphs Description
Page 77 and 78: maxdepth and maxdepth do not provid
Page 79 and 80: • magnetic_field1, magnetic_field
Page 81 and 82: 0 for pmin 100 for pmax Attribute o
Page 83 and 84: min sets the minimum number of iter
Page 85 and 86: This parameter only influences the
Page 87 and 88: • tempscheme Type: integer Defaul
Page 89 and 90: For details on user actions, see se
Page 91 and 92: screen, i. e. the x and y coordinat
Page 93 and 94: 5.8 Node Attributes This section de
Page 95 and 96: AISEEICONS can be set to the direct
Page 97 and 98: Description: Specifies the horizont
Page 99 and 100: Description: In a hierarchical layo
Page 101 and 102: - ”solid” Arrow head is a trian
Page 103 and 104: - dotted The edge consists of singl
Page 105 and 106: 5.10 Colors aiSee has a color map o
Page 107 and 108: PostScript, the original PostScript
Page 109 and 110: 5.12 User Action aiSee supports the
Page 111 and 112: - Selecting special characters Spec
Page 113: egion_attribute : “source” “:
Page 117 and 118: 6.4 Hierarchical Layout 6.4.1 Rank
Page 119 and 120: The ordering of nodes within one le
Page 121 and 122: 7 Tables 7.1 Node Attributes Table
Page 123 and 124: Key Menu Item Command Navigation Co
Page 125 and 126: -notune | -nofinetune See finetunin
Page 127 and 128: -d minindeg | -d minindegree See la
Page 129 and 130: -view dcfish See view (p. 90). -vie
Page 131 and 132: a4 | A4 A4 (21 cm x 30 cm) b5 | B5
Page 133 and 134: -canim Animates the crossing reduct
Page 135 and 136: [WiMa92] Wilhelm, Reinhard; Maurer,
Page 137 and 138: -nomanhattan, 125 -nonearedge, 126
Page 139 and 140: edge style continuous, 102 dashed,
Page 141 and 142: near_edges, 80 nearedge, 44, 111 ne
Page 143: xspace, 92, 119 y, 90 ybase, 91 yma
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