Question

我是JUNG的新手我有一个FRLayout，表示一个网络拓扑，其关键节点或顶点颜色为红色，其他顶点为蓝色从起始节点到结束节点的边缘是蓝色的我想要演示结束节点路径的动画。如何使用指定的时间间隔将start_node的边缘绘制为end_node？你能提供或参考一个例子吗？

Answer 1

您可以将关键帧附加到Edge数据。然后，每次绘制（使用变换器）时，您都可以使用关键帧调整边缘的渐变：

RenderContext<V, E> context = vv.getRenderContext();
context.setEdgeDrawPaintTransformer(new KeyframeGradientTransformer());

public class KeyframeGradientTransformer() implements Transformer<E, Paint> {
        @Override
        public Paint transform(Edge edge) {
            // TODO: Here you would determine the gradient information
            // based on the edge.getKeyframe().
            Paint gradient = new GradientPaint(...);
            return gradient;
        }
}

编辑：

我写了一个简单的例子：

enter image description here

这从一个顶点到另一个顶点（沿着一条边）动画。如果要通过多个顶点设置动画，则需要更多逻辑。但是，这看起来很酷，应该给你一个开始。如果您（或其他任何人）需要更多评论，请告诉我，我可以尝试更清楚。

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.LinearGradientPaint;
import java.awt.Paint;
import java.awt.Stroke;
import java.awt.geom.Point2D;
import java.util.Timer;
import java.util.TimerTask;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

import org.apache.commons.collections15.Factory;
import org.apache.commons.collections15.Transformer;

import edu.uci.ics.jung.algorithms.generators.random.EppsteinPowerLawGenerator;
import edu.uci.ics.jung.algorithms.layout.Layout;
import edu.uci.ics.jung.algorithms.layout.SpringLayout;
import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.graph.SparseMultigraph;
import edu.uci.ics.jung.graph.util.Pair;
import edu.uci.ics.jung.visualization.VisualizationViewer;

public class Test {

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.setPreferredSize(new Dimension(1024, 768));
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                JPanel content = new JPanel();

                // Set up the graph and the display.
                int numV = 70;
                int numE = 50;
                EppsteinPowerLawGenerator<String, String> gen = new EppsteinPowerLawGenerator<String, String>(
                        new GraphFactory(), new CountFactory(),
                        new CountFactory(), numV, numE, 10);
                Graph<String, String> graph = gen.create();
                Layout<String, String> layout = new SpringLayout<String, String>(
                        graph);
                VisualizationViewer<String, String> vv = new VisualizationViewer<String, String>(
                        layout);
                vv.getRenderContext().setEdgeStrokeTransformer(
                        new Transformer<String, Stroke>() {

                            @Override
                            public Stroke transform(String edge) {
                                return new BasicStroke(1.5f);
                            }
                        });

                content.add(vv);

                frame.setContentPane(content);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);

                // Animate the edges!
                AnimationTimerTask at = new AnimationTimerTask(vv);
                Timer timer = new Timer();
                timer.scheduleAtFixedRate(at, 10, 30);
            }

        });
    }

    static class AnimationTimerTask extends TimerTask {

        private final double width = 0.1; // Size of the colored line.
        private final double stepsize = 0.01;
        private double keyframe = 0 + width; // Between 0.0 and 1.0
        private VisualizationViewer<String, String> vv = null;

        public AnimationTimerTask(VisualizationViewer<String, String> vv) {
            this.vv = vv;
        }

        @Override
        public void run() {
            vv.getRenderContext().setEdgeDrawPaintTransformer(
                    new Transformer<String, Paint>() {

                        @Override
                        public Paint transform(String edge) {
                            // Find both points of the edge.
                            Pair<String> vs = vv.getGraphLayout().getGraph()
                                    .getEndpoints(edge);
                            Point2D p1 = vv.getGraphLayout().transform(
                                    vs.getFirst());
                            Point2D p2 = vv.getGraphLayout().transform(
                                    vs.getSecond());

                            // This code won't handle self-edges.
                            if (p1.equals(p2)) {
                                return Color.red;
                            }

                            Color[] colors = { Color.gray, Color.red,
                                    Color.gray };
                            float start = (float) Math.max(0.0, keyframe
                                    - width);
                            float end = (float) Math.min(1.0, keyframe + width);
                            float[] fractions = { start, (float) keyframe, end };
                            return new LinearGradientPaint(p1, p2, fractions,
                                    colors);
                        }

                    });
            vv.repaint();
            keyframe += stepsize;
            keyframe %= 1.0;
        }
    }

    static class GraphFactory implements Factory<Graph<String, String>> {

        @Override
        public Graph<String, String> create() {
            return new SparseMultigraph<String, String>();
        }
    }

    static class CountFactory implements Factory<String> {

        private int count = 0;

        @Override
        public String create() {
            return String.valueOf(count++);
        }
    }
}

另外，我之前为此采取了一些热度：这需要JUNG库。如果您没有，则无法运行SSCCEE。

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