How to zoom into a GraphStream View?

问题

In GraphStream visualizations Graphs can be dense. The enableAutoLayout method gives a global visualization of the Graph and so zooming is needed. How to zoom into a GraphStream View?

Graph go=...;
Viewer viewer = new Viewer(go, Viewer.ThreadingModel.GRAPH_IN_ANOTHER_THREAD);
viewer.enableAutoLayout();
View view = viewer.addDefaultView(false); 
swingNode.setContent((JComponent) view);

回答1:

I tried to find a way to zoom to the mouse cursor using the mouse wheel and stumbled across this thread, hoping to find an answer. I figured out how to zoom to the mouse eventually with GraphStream:

The zoom-factor for each mouse wheel rotation in my case is 1.25 (or 0.8 when zooming out). The code calculates the new center of the graph based on the original center of the graph, the clicked point in the graph, the zoom and eventually the ratio of Px to Gu which can be retrieved from the camera.

final Viewer viewer = new Viewer(graph, Viewer.ThreadingModel.GRAPH_IN_ANOTHER_THREAD);
viewer.enableAutoLayout();
final View view = viewer.addDefaultView(false);
view.getCamera().setViewPercent(1);
((Component) view).addMouseWheelListener(new MouseWheelListener() {
    @Override
    public void mouseWheelMoved(MouseWheelEvent e) {
        e.consume();
        int i = e.getWheelRotation();
        double factor = Math.pow(1.25, i);
        Camera cam = view.getCamera();
        double zoom = cam.getViewPercent() * factor;
        Point2 pxCenter  = cam.transformGuToPx(cam.getViewCenter().x, cam.getViewCenter().y, 0);
        Point3 guClicked = cam.transformPxToGu(e.getX(), e.getY());
        double newRatioPx2Gu = cam.getMetrics().ratioPx2Gu/factor;
        double x = guClicked.x + (pxCenter.x - e.getX())/newRatioPx2Gu;
        double y = guClicked.y - (pxCenter.y - e.getY())/newRatioPx2Gu;
        cam.setViewCenter(x, y, 0);
        cam.setViewPercent(zoom);
    }
});

回答2:

Here a simple code to show you how you can zoom a graph:

public class zoomGraph{

   public zoomGraph(){
   }
   //the methode that will zoom the graph
   public static void zoomGraphMouseWheelMoved(MouseWheelEvent mwe, ViewPanel view_panel){
        if (Event.ALT_MASK != 0) {            
            if (mwe.getWheelRotation() > 0) {
                double new_view_percent = view_panel.getCamera().getViewPercent() + 0.05;
                view_panel.getCamera().setViewPercent(new_view_percent);               
            } else if (mwe.getWheelRotation() < 0) {
                double current_view_percent = view_panel.getCamera().getViewPercent();
                if(current_view_percent > 0.05){
                    view_panel.getCamera().setViewPercent(current_view_percent - 0.05);                
                }
            }
        }                     
    }

    public static void main(String[] args) {

        JFrame frame = new JFrame();
        frame.setLayout(new GridLayout());
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);        
        frame.setBounds(0, 0, 700, 500);
        frame.setPreferredSize(new Dimension(700, 500));


        //Components
        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout());
        frame.add(panel);

        //create a simple graph
        Graph graph = new SingleGraph("tuto_zoom", false, true);
        graph.addNode("node_1");
        graph.addNode("node_2");
        graph.addEdge("edge_1_2", "node_1","node_2");

        //show the graph in the panel
        Viewer viewer = new Viewer(graph, Viewer.ThreadingModel.GRAPH_IN_ANOTHER_THREAD);
        viewer.enableAutoLayout();
        ViewPanel view_panel = viewer.addDefaultView(false); 
        Rectangle rec = panel.getBounds();
        view_panel.setBounds(0, 0, rec.width, rec.height);
        view_panel.setPreferredSize(new Dimension(rec.width, rec.height));
        panel.add(view_panel);


        //add a mouse wheel listener to the ViewPanel for zooming the graph
        view_panel.addMouseWheelListener(new MouseWheelListener() {
            @Override
            public void mouseWheelMoved(MouseWheelEvent mwe) {
                zoomGraph.zoomGraphMouseWheelMoved(mwe, view_panel);
            }
        });


        frame.setVisible(true);
    }

}

回答3:

From the official documentation at http://graphstream-project.org/doc/Tutorials/Graph-Visualisation:

You can also zoom in or out using:

view.getCamera().setViewPercent(0.5);

This will zoom of 200% on the view center.

来源：https://stackoverflow.com/questions/44675827/how-to-zoom-into-a-graphstream-view