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Gef Examples

A Gef component.

Basic Snippet

Gef Basic Snippet

The smallest useful GEF example: a {@link ScrollingGraphicalViewer} driven from a plain Shell,

with no workbench.

Where the draw2d snippets exercise a {@code FigureCanvas} directly, this one goes through GEF's own stack -- {@link EditPartFactory}, {@link AbstractGraphicalEditPart}, {@link EditDomain} and a {@link ScalableRootEditPart} -- which is how an application actually builds a diagram. The viewer's figures are laid out well beyond the shell's client area, so the viewport scrolls and the scrolled repaint path is covered too. ??? example "GefBasicSnippet.java" 

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package dev.equo.gef;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.draw2d.ColorConstants;
import org.eclipse.draw2d.Figure;
import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.Label;
import org.eclipse.draw2d.LineBorder;
import org.eclipse.draw2d.XYLayout;
import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.gef.EditDomain;
import org.eclipse.gef.EditPart;
import org.eclipse.gef.EditPartFactory;
import org.eclipse.gef.GraphicalEditPart;
import org.eclipse.gef.editparts.AbstractGraphicalEditPart;
import org.eclipse.gef.editparts.ScalableRootEditPart;
import org.eclipse.gef.ui.parts.ScrollingGraphicalViewer;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

/**
 * The smallest useful GEF example: a {@link ScrollingGraphicalViewer} driven from a plain Shell,
 * with no workbench.
 * <p>
 * Where the draw2d snippets exercise a {@code FigureCanvas} directly, this one goes through GEF's
 * own stack -- {@link EditPartFactory}, {@link AbstractGraphicalEditPart}, {@link EditDomain} and a
 * {@link ScalableRootEditPart} -- which is how an application actually builds a diagram. The
 * viewer's figures are laid out well beyond the shell's client area, so the viewport scrolls and
 * the scrolled repaint path is covered too.
 */
public class GefBasicSnippet {

    /** Model: a named box at a fixed position, optionally linked to the previous one. */
    private record Node(String name, Rectangle bounds) {
    }

    private static class NodeEditPart extends AbstractGraphicalEditPart {
        @Override
        protected IFigure createFigure() {
            Label label = new Label(((Node) getModel()).name());
            label.setOpaque(true);
            label.setBackgroundColor(ColorConstants.lightGray);
            label.setBorder(new LineBorder(ColorConstants.blue, 2));
            return label;
        }

        @Override
        protected void createEditPolicies() {
        }

        @Override
        protected void refreshVisuals() {
            ((GraphicalEditPart) getParent()).setLayoutConstraint(this, getFigure(),
                    ((Node) getModel()).bounds());
        }
    }

    private static class DiagramEditPart extends AbstractGraphicalEditPart {
        @Override
        protected IFigure createFigure() {
            Figure figure = new Figure();
            figure.setLayoutManager(new XYLayout());
            return figure;
        }

        @Override
        protected void createEditPolicies() {
        }

        @Override
        @SuppressWarnings("unchecked")
        protected List<Node> getModelChildren() {
            return (List<Node>) getModel();
        }
    }

    private static class DiagramEditPartFactory implements EditPartFactory {
        @Override
        public EditPart createEditPart(EditPart context, Object model) {
            AbstractGraphicalEditPart part = (model instanceof Node) ? new NodeEditPart()
                    : new DiagramEditPart();
            part.setModel(model);
            return part;
        }
    }

    private static List<Node> createModel() {
        List<Node> nodes = new ArrayList<>();
        for (int row = 0; row < 6; row++) {
            for (int col = 0; col < 4; col++) {
                nodes.add(new Node("Node " + (row * 4 + col + 1),
                        new Rectangle(40 + col * 220, 40 + row * 130, 140, 60)));
            }
        }
        return nodes;
    }

    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setLayout(new FillLayout());
        shell.setText("GEF Basic");

        ScrollingGraphicalViewer viewer = new ScrollingGraphicalViewer();
        viewer.createControl(shell);
        viewer.setRootEditPart(new ScalableRootEditPart());
        viewer.setEditDomain(new EditDomain());
        viewer.setEditPartFactory(new DiagramEditPartFactory());
        viewer.setContents(createModel());

        shell.setSize(600, 450);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }
}
[View on GitHub :simple-github:](https://github.com/equodev/swt-evolve/blob/main/examples/src/main/java/dev/equo/gef/GefBasicSnippet.java){ .md-button } ### Connections Snippet [![Gef Connections Snippet](assets/screenshots/GefConnectionsSnippet.png)](assets/screenshots/GefConnectionsSnippet.png){.glightbox} A GEF viewer whose nodes are joined by connections on the root part's connection layer.

Where {@link GefBasicSnippet} only paints node figures on the primary layer, this exercises the layered side of a GEF diagram: connections live on {@link LayerConstants#CONNECTION_LAYER}, and each one re-routes itself off its endpoints' {@link ChopboxAnchor}s rather than being positioned by the layout. ??? example "GefConnectionsSnippet.java" 

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package dev.equo.gef;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.draw2d.ChopboxAnchor;
import org.eclipse.draw2d.ColorConstants;
import org.eclipse.draw2d.Figure;
import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.Label;
import org.eclipse.draw2d.LineBorder;
import org.eclipse.draw2d.PolygonDecoration;
import org.eclipse.draw2d.PolylineConnection;
import org.eclipse.draw2d.XYLayout;
import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.gef.EditDomain;
import org.eclipse.gef.EditPart;
import org.eclipse.gef.EditPartFactory;
import org.eclipse.gef.GraphicalEditPart;
import org.eclipse.gef.LayerConstants;
import org.eclipse.gef.editparts.AbstractGraphicalEditPart;
import org.eclipse.gef.editparts.ScalableRootEditPart;
import org.eclipse.gef.ui.parts.ScrollingGraphicalViewer;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

/**
 * A GEF viewer whose nodes are joined by connections on the root part's connection layer.
 * <p>
 * Where {@link GefBasicSnippet} only paints node figures on the primary layer, this exercises the
 * layered side of a GEF diagram: connections live on {@link LayerConstants#CONNECTION_LAYER}, and
 * each one re-routes itself off its endpoints' {@link ChopboxAnchor}s rather than being positioned
 * by the layout.
 */
public class GefConnectionsSnippet {

    private record Node(String name, Rectangle bounds) {
    }

    private static class NodeEditPart extends AbstractGraphicalEditPart {
        @Override
        protected IFigure createFigure() {
            Label label = new Label(((Node) getModel()).name());
            label.setOpaque(true);
            label.setBackgroundColor(ColorConstants.lightGray);
            label.setBorder(new LineBorder(ColorConstants.darkBlue, 2));
            return label;
        }

        @Override
        protected void createEditPolicies() {
        }

        @Override
        protected void refreshVisuals() {
            ((GraphicalEditPart) getParent()).setLayoutConstraint(this, getFigure(),
                    ((Node) getModel()).bounds());
        }
    }

    private static class DiagramEditPart extends AbstractGraphicalEditPart {
        @Override
        protected IFigure createFigure() {
            Figure figure = new Figure();
            figure.setLayoutManager(new XYLayout());
            return figure;
        }

        @Override
        protected void createEditPolicies() {
        }

        @Override
        @SuppressWarnings("unchecked")
        protected List<Node> getModelChildren() {
            return (List<Node>) getModel();
        }
    }

    private static class DiagramEditPartFactory implements EditPartFactory {
        @Override
        public EditPart createEditPart(EditPart context, Object model) {
            AbstractGraphicalEditPart part = (model instanceof Node) ? new NodeEditPart()
                    : new DiagramEditPart();
            part.setModel(model);
            return part;
        }
    }

    /** Draws an arrow from the figure of {@code from} to the figure of {@code to}. */
    private static void connect(ScrollingGraphicalViewer viewer, Node from, Node to) {
        IFigure source = ((GraphicalEditPart) viewer.getEditPartRegistry().get(from)).getFigure();
        IFigure target = ((GraphicalEditPart) viewer.getEditPartRegistry().get(to)).getFigure();

        PolylineConnection connection = new PolylineConnection();
        connection.setSourceAnchor(new ChopboxAnchor(source));
        connection.setTargetAnchor(new ChopboxAnchor(target));
        connection.setTargetDecoration(new PolygonDecoration());
        connection.setForegroundColor(ColorConstants.darkBlue);

        IFigure connectionLayer = ((ScalableRootEditPart) viewer.getRootEditPart())
                .getLayer(LayerConstants.CONNECTION_LAYER);
        connectionLayer.add(connection);
    }

    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setLayout(new FillLayout());
        shell.setText("GEF Connections");

        List<Node> nodes = new ArrayList<>();
        Node root = new Node("Root", new Rectangle(190, 30, 120, 50));
        Node left = new Node("Left", new Rectangle(40, 170, 120, 50));
        Node right = new Node("Right", new Rectangle(340, 170, 120, 50));
        Node leaf = new Node("Leaf", new Rectangle(190, 300, 120, 50));
        nodes.add(root);
        nodes.add(left);
        nodes.add(right);
        nodes.add(leaf);

        ScrollingGraphicalViewer viewer = new ScrollingGraphicalViewer();
        viewer.createControl(shell);
        viewer.setRootEditPart(new ScalableRootEditPart());
        viewer.setEditDomain(new EditDomain());
        viewer.setEditPartFactory(new DiagramEditPartFactory());
        viewer.setContents(nodes);

        // After setContents, so every node already has an EditPart (and a figure) to anchor to.
        connect(viewer, root, left);
        connect(viewer, root, right);
        connect(viewer, left, leaf);
        connect(viewer, right, leaf);

        shell.setSize(540, 420);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }
}
[View on GitHub :simple-github:](https://github.com/equodev/swt-evolve/blob/main/examples/src/main/java/dev/equo/gef/GefConnectionsSnippet.java){ .md-button } ### Selection Snippet [![Gef Selection Snippet](assets/screenshots/GefSelectionSnippet.png)](assets/screenshots/GefSelectionSnippet.png){.glightbox} A GEF viewer with selectable nodes, one of them selected on open.

Selection handles are not part of any node's own figure: GEF puts them on the root part's handle layer, painted outside the ordinary figure pass. That makes this the snippet that covers the layer a diagram editor uses for everything it draws *about* the diagram rather than *in* it. ??? example "GefSelectionSnippet.java" 

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package dev.equo.gef;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.draw2d.ColorConstants;
import org.eclipse.draw2d.Figure;
import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.Label;
import org.eclipse.draw2d.LineBorder;
import org.eclipse.draw2d.XYLayout;
import org.eclipse.draw2d.geometry.Rectangle;
import org.eclipse.gef.EditDomain;
import org.eclipse.gef.EditPart;
import org.eclipse.gef.EditPartFactory;
import org.eclipse.gef.EditPolicy;
import org.eclipse.gef.GraphicalEditPart;
import org.eclipse.gef.editparts.AbstractGraphicalEditPart;
import org.eclipse.gef.editparts.ScalableRootEditPart;
import org.eclipse.gef.editpolicies.NonResizableEditPolicy;
import org.eclipse.gef.ui.parts.ScrollingGraphicalViewer;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

/**
 * A GEF viewer with selectable nodes, one of them selected on open.
 * <p>
 * Selection handles are not part of any node's own figure: GEF puts them on the root part's handle
 * layer, painted outside the ordinary figure pass. That makes this the snippet that covers the
 * layer a diagram editor uses for everything it draws *about* the diagram rather than *in* it.
 */
public class GefSelectionSnippet {

    private record Node(String name, Rectangle bounds) {
    }

    private static class NodeEditPart extends AbstractGraphicalEditPart {
        @Override
        protected IFigure createFigure() {
            Label label = new Label(((Node) getModel()).name());
            label.setOpaque(true);
            label.setBackgroundColor(ColorConstants.lightGray);
            label.setBorder(new LineBorder(ColorConstants.gray, 1));
            return label;
        }

        @Override
        protected void createEditPolicies() {
            // What gives the part its selection handles once the viewer selects it.
            installEditPolicy(EditPolicy.PRIMARY_DRAG_ROLE, new NonResizableEditPolicy());
        }

        @Override
        protected void refreshVisuals() {
            ((GraphicalEditPart) getParent()).setLayoutConstraint(this, getFigure(),
                    ((Node) getModel()).bounds());
        }
    }

    private static class DiagramEditPart extends AbstractGraphicalEditPart {
        @Override
        protected IFigure createFigure() {
            Figure figure = new Figure();
            figure.setLayoutManager(new XYLayout());
            return figure;
        }

        @Override
        protected void createEditPolicies() {
        }

        @Override
        @SuppressWarnings("unchecked")
        protected List<Node> getModelChildren() {
            return (List<Node>) getModel();
        }
    }

    private static class DiagramEditPartFactory implements EditPartFactory {
        @Override
        public EditPart createEditPart(EditPart context, Object model) {
            AbstractGraphicalEditPart part = (model instanceof Node) ? new NodeEditPart()
                    : new DiagramEditPart();
            part.setModel(model);
            return part;
        }
    }

    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setLayout(new FillLayout());
        shell.setText("GEF Selection");

        List<Node> nodes = new ArrayList<>();
        for (int i = 0; i < 6; i++) {
            nodes.add(new Node("Node " + (i + 1),
                    new Rectangle(50 + (i % 3) * 160, 60 + (i / 3) * 140, 120, 60)));
        }

        ScrollingGraphicalViewer viewer = new ScrollingGraphicalViewer();
        viewer.createControl(shell);
        viewer.setRootEditPart(new ScalableRootEditPart());
        viewer.setEditDomain(new EditDomain());
        viewer.setEditPartFactory(new DiagramEditPartFactory());
        viewer.setContents(nodes);

        // Selecting from code rather than by click keeps the snippet deterministic when captured.
        EditPart selected = (EditPart) viewer.getEditPartRegistry().get(nodes.get(1));
        viewer.select(selected);

        shell.setSize(560, 380);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }
}
[View on GitHub :simple-github:](https://github.com/equodev/swt-evolve/blob/main/examples/src/main/java/dev/equo/gef/GefSelectionSnippet.java){ .md-button }