graphview 1.5.0

GraphView is used to display data in graph structures. It can display Tree layout, Directed and Layered graph. Useful for Family Tree, Hierarchy View.

GraphView

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Flutter GraphView is used to display data in graph structures. It can display Tree layout, Directed and Layered graph. Useful for Family Tree, Hierarchy View.

Overview

The library is designed to support different graph layouts and currently works excellent with small graphs. It now includes advanced features like node animations, expand/collapse functionality, and automatic camera positioning.

You can have a look at the flutter web implementation here: http://graphview.surge.sh/

Features

• Multiple Layout Algorithms: Tree, Directed Graph, Layered Graph, Balloon, Circular, Radial, Tidier Tree, and Mindmap layouts
• Node Animations: Smooth expand/collapse animations with customizable duration
• Interactive Navigation: Jump to nodes, zoom to fit, auto-centering capabilities
• Node Expand/Collapse: Hierarchical node visibility control with animated transitions
• Customizable Rendering: Custom edge renderers, paint styling, and node builders
• Touch Interactions: Pan, zoom, and tap handling with InteractiveViewer integration

Layouts

Tree

Uses Walker's algorithm with Buchheim's runtime improvements (BuchheimWalkerAlgorithm class). Supports different orientations. All you have to do is using the BuchheimWalkerConfiguration.orientation with either ORIENTATION_LEFT_RIGHT, ORIENTATION_RIGHT_LEFT, ORIENTATION_TOP_BOTTOM and ORIENTATION_BOTTOM_TOP (default). Furthermore parameters like sibling-, level-, subtree separation can be set.

Useful for: Family Tree, Hierarchy View, Flutter Widget Tree

Tidier Tree

An improved tree layout algorithm (TidierTreeLayoutAlgorithm class) that provides better spacing and positioning for complex hierarchical structures. Supports all orientations and provides cleaner node arrangements.

Useful for: Complex hierarchies, Organizational charts, Decision trees

Directed graph

Directed graph drawing by simulating attraction/repulsion forces. For this the algorithm by Fruchterman and Reingold (FruchtermanReingoldAlgorithm class) was implemented.

Useful for: Social network, Mind Map, Cluster, Graphs, Intercity Road Network

Layered graph

Algorithm from Sugiyama et al. for drawing multilayer graphs, taking advantage of the hierarchical structure of the graph (SugiyamaAlgorithm class). You can also set the parameters for node and level separation using the SugiyamaConfiguration. Supports different orientations. All you have to do is using the SugiyamaConfiguration.orientation with either ORIENTATION_LEFT_RIGHT, ORIENTATION_RIGHT_LEFT, ORIENTATION_TOP_BOTTOM and ORIENTATION_BOTTOM_TOP (default).

Useful for: Hierarchical Graph which it can have weird edges/multiple paths

Balloon Layout

A radial tree layout (BalloonLayoutAlgorithm class) that arranges child nodes in circular patterns around their parents. Creates balloon-like structures that are visually appealing for hierarchical data.

Useful for: Mind maps, Radial trees, Circular hierarchies

Circular Layout

Arranges all nodes in a circle (CircleLayoutAlgorithm class). Includes edge crossing reduction algorithms for better readability. Supports automatic radius calculation and custom positioning.

Useful for: Network visualization, Relationship diagrams, Cyclic structures

Radial Tree Layout

A tree layout that converts traditional tree structures into radial/polar coordinates (RadialTreeLayoutAlgorithm class). Nodes are positioned based on their distance from the root and angular position.

Useful for: Radial dendrograms, Phylogenetic trees, Sunburst-style hierarchies

Mindmap Layout

Specialized layout for mindmap-style visualizations (MindmapAlgorithm class) where child nodes are distributed on left and right sides of the root node.

Useful for: Mind maps, Concept maps, Brainstorming diagrams

Usage

Basic Setup

Currently GraphView must be used together with a Zoom Engine like InteractiveViewer. To change the zoom values just use the different attributes described in the InteractiveViewer class.

To create a graph, we need to instantiate the Graph class. Then we need to pass the layout and also optional the edge renderer.

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) => MaterialApp(
        home: TreeViewPage(),
      );
}

class TreeViewPage extends StatefulWidget {
  @override
  _TreeViewPageState createState() => _TreeViewPageState();
}

class _TreeViewPageState extends State<TreeViewPage> {
  final GraphViewController controller = GraphViewController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Column(
      mainAxisSize: MainAxisSize.max,
      children: [
        Wrap(
          children: [
            Container(
              width: 100,
              child: TextFormField(
                initialValue: builder.siblingSeparation.toString(),
                decoration: InputDecoration(labelText: "Sibling Separation"),
                onChanged: (text) {
                  builder.siblingSeparation = int.tryParse(text) ?? 100;
                  this.setState(() {});
                },
              ),
            ),
            Container(
              width: 100,
              child: TextFormField(
                initialValue: builder.levelSeparation.toString(),
                decoration: InputDecoration(labelText: "Level Separation"),
                onChanged: (text) {
                  builder.levelSeparation = int.tryParse(text) ?? 100;
                  this.setState(() {});
                },
              ),
            ),
            Container(
              width: 100,
              child: TextFormField(
                initialValue: builder.subtreeSeparation.toString(),
                decoration: InputDecoration(labelText: "Subtree separation"),
                onChanged: (text) {
                  builder.subtreeSeparation = int.tryParse(text) ?? 100;
                  this.setState(() {});
                },
              ),
            ),
            Container(
              width: 100,
              child: TextFormField(
                initialValue: builder.orientation.toString(),
                decoration: InputDecoration(labelText: "Orientation"),
                onChanged: (text) {
                  builder.orientation = int.tryParse(text) ?? 100;
                  this.setState(() {});
                },
              ),
            ),
            ElevatedButton(
              onPressed: () {
                final node12 = Node.Id(r.nextInt(100));
                var edge = graph.getNodeAtPosition(r.nextInt(graph.nodeCount()));
                print(edge);
                graph.addEdge(edge, node12);
                setState(() {});
              },
              child: Text("Add"),
            )
          ],
        ),
        Expanded(
          child: GraphView.builder(
              graph: graph,
              algorithm: BuchheimWalkerAlgorithm(builder, TreeEdgeRenderer(builder)),
              controller: controller,
              animated: true,
              autoZoomToFit: true,
              builder: (Node node) {
                // I can decide what widget should be shown here based on the id
                var a = node.key.value as int;
                return rectangleWidget(a);
              },
          ),
        ),
      ],
    ));
  }

  Random r = Random();

  Widget rectangleWidget(int a) {
    return InkWell(
      onTap: () {
        print('clicked');
      },
      child: Container(
          padding: EdgeInsets.all(16),
          decoration: BoxDecoration(
            borderRadius: BorderRadius.circular(4),
            boxShadow: [
              BoxShadow(color: Colors.blue[100], spreadRadius: 1),
            ],
          ),
          child: Text('Node ${a}')),
    );
  }

  final Graph graph = Graph()..isTree = true;
  BuchheimWalkerConfiguration builder = BuchheimWalkerConfiguration();

  @override
  void initState() {
    final node1 = Node.Id(1);
    final node2 = Node.Id(2);
    final node3 = Node.Id(3);
    final node4 = Node.Id(4);
    final node5 = Node.Id(5);
    final node6 = Node.Id(6);
    final node8 = Node.Id(7);
    final node7 = Node.Id(8);
    final node9 = Node.Id(9);
    final node10 = Node.Id(10);  
    final node11 = Node.Id(11);
    final node12 = Node.Id(12);

    graph.addEdge(node1, node2);
    graph.addEdge(node1, node3, paint: Paint()..color = Colors.red);
    graph.addEdge(node1, node4, paint: Paint()..color = Colors.blue);
    graph.addEdge(node2, node5);
    graph.addEdge(node2, node6);
    graph.addEdge(node6, node7, paint: Paint()..color = Colors.red);
    graph.addEdge(node6, node8, paint: Paint()..color = Colors.red);
    graph.addEdge(node4, node9);
    graph.addEdge(node4, node10, paint: Paint()..color = Colors.black);
    graph.addEdge(node4, node11, paint: Paint()..color = Colors.red);
    graph.addEdge(node11, node12);

    builder
      ..siblingSeparation = (100)
      ..levelSeparation = (150)
      ..subtreeSeparation = (150)
      ..orientation = (BuchheimWalkerConfiguration.ORIENTATION_TOP_BOTTOM);
  }
}

Advanced Features

GraphView.builder

The enhanced GraphView.builder constructor provides additional capabilities:

GraphView.builder(
  graph: graph,
  algorithm: BuchheimWalkerAlgorithm(config, TreeEdgeRenderer(config)),
  controller: controller,
  animated: true,                    // Enable smooth animations
  autoZoomToFit: true,              // Automatically zoom to fit all nodes
  initialNode: ValueKey('startNode'), // Jump to specific node on init
  panAnimationDuration: Duration(milliseconds: 600),
  toggleAnimationDuration: Duration(milliseconds: 400),
  centerGraph: true,                // Center the graph in viewport
  builder: (Node node) {
    return YourCustomWidget(node);
  },
)

Node Expand/Collapse

Use the GraphViewController to manage node visibility:

final controller = GraphViewController();

// Collapse a node (hide its children)
controller.collapseNode(graph, node, animate: true);

// Expand a collapsed node
controller.expandNode(graph, node, animate: true);

// Toggle collapse/expand state
controller.toggleNodeExpanded(graph, node, animate: true);

// Check if node is collapsed
bool isCollapsed = controller.isNodeCollapsed(node);

// Set initially collapsed nodes
controller.setInitiallyCollapsedNodes([node1, node2]);

Navigation and Camera Control

Navigate programmatically through the graph:

// Jump to a specific node
controller.jumpToNode(ValueKey('nodeId'));

// Animate to a node
controller.animateToNode(ValueKey('nodeId'));

// Zoom to fit all visible nodes
controller.zoomToFit();

// Reset view to origin
controller.resetView();

// Force recalculation of layout
controller.forceRecalculation();

Algorithm Examples

Balloon Layout

GraphView.builder(
  graph: graph,
  algorithm: BalloonLayoutAlgorithm(
    BuchheimWalkerConfiguration(), 
    null
  ),
  builder: (node) => nodeWidget(node),
)

Circular Layout

GraphView.builder(
  graph: graph,
  algorithm: CircleLayoutAlgorithm(
    CircleLayoutConfiguration(
      radius: 200.0,
      reduceEdgeCrossing: true,
    ), 
    null
  ),
  builder: (node) => nodeWidget(node),
)

Radial Tree Layout

GraphView.builder(
  graph: graph,
  algorithm: RadialTreeLayoutAlgorithm(
    BuchheimWalkerConfiguration(), 
    null
  ),
  builder: (node) => nodeWidget(node),
)

Tidier Tree Layout

GraphView.builder(
  graph: graph,
  algorithm: TidierTreeLayoutAlgorithm(
    BuchheimWalkerConfiguration(), 
    TreeEdgeRenderer(config)
  ),
  builder: (node) => nodeWidget(node),
)

Mindmap Layout

GraphView.builder(
  graph: graph,
  algorithm: MindmapAlgorithm(
    BuchheimWalkerConfiguration(), 
    MindmapEdgeRenderer(config)
  ),
  builder: (node) => nodeWidget(node),
)

Using builder mechanism to build Nodes

You can use any widget inside the node:

Node node = Node.Id(fromNodeId) ;

builder: (Node node) {
                  // I can decide what widget should be shown here based on the id
                  var a = node.key.value as int;
                  if(a ==2)
                    return rectangleWidget(a);
                  else 
                    return circleWidget(a);
                },

Using Paint to color and line thickness

You can specify the edge color and thickness by using a custom paint

getGraphView() {
        return GraphView(
                graph: graph,
                algorithm: SugiyamaAlgorithm(builder),
                paint: Paint()..color = Colors.green..strokeWidth = 1..style = PaintingStyle.stroke,
              );
}

Color Edges individually

Add an additional parameter paint. Applicable for ArrowEdgeRenderer for now.

var a = Node();
var b = Node();
 graph.addEdge(a, b, paint: Paint()..color = Colors.red);

Add focused Node

You can focus on a specific node. This will allow scrolling to that node in the future, but for now , using it we can drag a node with realtime updates in force directed graph

 onPanUpdate: (details) {
        var x = details.globalPosition.dx;
        var y = details.globalPosition.dy;
        setState(() {
          builder.setFocusedNode(graph.getNodeAtPosition(i));
          graph.getNodeAtPosition(i).position = Offset(x,y);
        });
      },

Extract info from any json to Graph Object

Now its a bit easy to use Ids to extract info from any json to Graph Object

For example, if the json is like this:

var json = {
   "nodes": [
     {"id": 1, "label": 'circle'},
     {"id": 2, "label": 'ellipse'},
     {"id": 3, "label": 'database'},
     {"id": 4, "label": 'box'},
     {"id": 5, "label": 'diamond'},
     {"id": 6, "label": 'dot'},
     {"id": 7, "label": 'square'},
     {"id": 8, "label": 'triangle'},
   ],
   "edges": [
     {"from": 1, "to": 2},
     {"from": 2, "to": 3},
     {"from": 2, "to": 4},
     {"from": 2, "to": 5},
     {"from": 5, "to": 6},
     {"from": 5, "to": 7},
     {"from": 6, "to": 8}
   ]
 };

Step 1, add the edges by using ids

  edges.forEach((element) {
      var fromNodeId = element['from'];
      var toNodeId = element['to'];
      graph.addEdge(Node.Id(fromNodeId), Node.Id(toNodeId));
    });

Step 2: Then using builder and find the nodeValues from the json using id and then set the value of that.

 builder: (Node node) {
                  // I can decide what widget should be shown here based on the id
                  var a = node.key.value as int;
                  var nodes = json['nodes'];
                  var nodeValue = nodes.firstWhere((element) => element['id'] == a);
                  return rectangleWidget(nodeValue['label'] as String);
                },

Using any widget inside the Node (Deprecated)

You can use any widget inside the node:

Node node = Node(getNodeText);

getNodeText() {
    return Container(
        padding: EdgeInsets.all(16),
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(4),
          boxShadow: [
            BoxShadow(color: Colors.blue[100], spreadRadius: 1),
          ],
        ),
        child: Text("Node ${n++}"));
  }

Examples

Rooted Tree

Rooted Tree (Bottom to Top)

Rooted Tree (Left to Right)

Rooted Tree (Right to Left)

Directed Graph

Layered Graph

Balloon Layout

Circular Layout

Radial Tree Layout

Tidier Tree Layout

Mindmap Layout

Node Expand/Collapse Animation

Auto Navigation

Inspirations

This library is basically a dart representation of the excellent Android Library GraphView by Team-Blox

I would like to thank them for open sourcing their code for which reason I was able to port their code to dart and use for flutter.

Future Works

• ✅ Add nodeOnTap
• ✅ Add Layered Graph
• ✅ Animations
• ✅ Dynamic Node Position update for directed graph
• ✅ Node expand/collapse functionality
• ✅ Auto-navigation and camera control
• ✅ Multiple new layout algorithms (Balloon, Circular, Radial, Tidier, Mindmap)
• ❌ Finish Eiglsperger Algorithm
• ❌ Custom Edge Label Rendering
• ❌ Use a builder pattern to draw items on demand.

License

MIT License

Copyright (c) 2020 Nabil Mosharraf

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.