graphpanelnormalstate.java

OpenJGraph是一个开源的Java库

package salvo.jesus.graph.visual;

import salvo.jesus.graph.*;
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;

/**
 * State object that represents the normal mode in a GraphPanel.
 * Normal mode being 1) drag vertex and right click on VisualGraphComponents
 * to cause a popup menu to be displayed.
 *
 * @author  Jesus M. Salvo Jr.
 */
public class GraphPanelNormalState extends GraphPanelState {
    /**
     * VisualVertex object selected during the mousePressed() method
     */
    VisualVertex  targetvertex;

    /**
     * VisualEdge object selected during the mousePressed() method
     */
    VisualEdge    targetedge;

    /**
     * Existing cursor prior to changing the cursor.
     */
    Cursor        previouscursor;

    /**
     * A Cursor object of type Cursor.MOVE_CURSOR
     */
    Cursor        movecursor;

    /**
     * Stores the previous x-coordinate of targetedvertex when dragging
     * a VisualVertex object.
     */
    int           previous_x;

    /**
     * Stores the previous y-coordinate of targetedvertex when dragging
     * a VisualVertex object.
     */
    int           previous_y;

    /**
     * Creates a GraphPanelNormalState object for the specified GraphPanel object.
     */
    public GraphPanelNormalState( GraphPanel gpanel ) {
        super( gpanel );
        this.movecursor = new Cursor( Cursor.MOVE_CURSOR );
    }

    public GraphPanelNormalState() {
        this(null);
    }

    /**
     * If there is a VisualGraphComponent at the coordinate specified
     * in the MouseEvent e, then a JPopupMenu will be shown
     * by calling the popup() method whose context is the selected
     * VisualGraphComponent.
     */
    public GraphPanelState mousePressed(MouseEvent e) {
        VisualGraphComponent     component;

        this.previous_x = e.getX();
        this.previous_y = e.getY();

        this.targetvertex = gpanel.getVisualGraph().getNode( this.previous_x, this.previous_y );
        this.targetedge = gpanel.getVisualGraph().getVisualEdge( this.previous_x, this.previous_y );

        if( e.isPopupTrigger()
                && (this.targetvertex != null || this.targetedge != null ))
            this.popup( this.previous_x, this.previous_y );

        // Notify the VisualGraphComponent of the event
        informTargetVisualGraphComponentOfMouseEvent(e);
        return this;
    }

    /**
     * Shows a popup menu if there was a VisualGraphComponent during the
     * mousePressed() event.
     */
    public GraphPanelState mouseReleased( MouseEvent e ) {
        // Different platforms return true for isPopupTrigger() on different events.
        // Some return true on mousePressed(), while other on mouseReleased().
        // Therefore, adaptee.vertexlicked or adaptee.edgeclicked may have been set on mousePressed(),
        // but the popup menu may not appear until mouseReleased().
        VisualGraphComponent    component;

        if( e.isPopupTrigger()
                && (this.targetvertex != null || this.targetedge != null ))
            this.popup( e.getX(), e.getY() );

        // Notify the VisualGraphComponent of the event
        informTargetVisualGraphComponentOfMouseEvent(e);

        // Do not forget to remove any reference to the vertex and edge that was clicked
        // during the mousePressed.
        this.targetvertex = null;
        this.targetedge = null;
        this.previous_x = e.getX();
        this.previous_y = e.getY();
        return this;
    }

    /**
     * If there was a VisualVertex object selected during the mousePressed() method,
     * then drag the VisualVertex object to the new location specfied by the
     * MouseEvent e.
     */
    public GraphPanelState mouseDragged( MouseEvent e ){
        if( this.targetvertex != null )
            this.dragVertex( e.getX(), e.getY() );

        // Notify the VisualGraphComponent of the event
        informTargetVisualGraphComponentOfMouseEvent(e);

        return this;
    }

    /**
     * This method is automatically called by the mouseDragged() method
     * if there was a VisualVertex selected during the mousePressed() method,
     * to drag the selected VisualVertex object to the specifid coordinate.
     *
     * @param   x   New x coordinate
     * @param   y   New y coordinate
     *
     */
    private void dragVertex( int x, int y ) {
        Rectangle     vertexrect;
        int                                 deltax, deltay;

        vertexrect = this.targetvertex.getBounds();

        // Do not allow coordinates to be negative, as there is no way
        // to adjust the scrollbars of JScrollPane to set the viewport to negative
        // by default.
        deltax = vertexrect.x + x - this.previous_x < 0 ? -vertexrect.x : x - this.previous_x;
        deltay = vertexrect.y + y - this.previous_y < 0 ? -vertexrect.y : y - this.previous_y;

        // Now drag the vertex to its new location.
        this.targetvertex.setLocationDelta( deltax, deltay );

        // Make the current coordinate the "previous" coordinate for
        // the next mouseDragged event
        this.previous_x = this.previous_x + deltax;
        this.previous_y = this.previous_y + deltay;

        gpanel.vgraph.repaint();
    }

    /**
     * Creates and shows a JPopMenu object, whose context is the
     * VisualGraphComponent selected during the mousePressed() event.
     *
     * @param   x     The x-coordinate where the popup menu will be shown.
     * @param   y     The y-coordinate where the popup menu will be shown.
     */
    private void popup( int x, int y ) {
        JPopupMenu  popup;
        JMenuItem   propertiesmenuitem;
        JMenuItem           deletemenuitem;

        // Show a popup menu for a vertex
        if( this.targetvertex != null ) {
            popup = new JPopupMenu();
            propertiesmenuitem = new JMenuItem( "Vertex Properties..." );
            deletemenuitem = new JMenuItem( "Delete Vertex" );

            popup.add( propertiesmenuitem );
            popup.addSeparator();
            popup.add( deletemenuitem );

            // Specify what action to take when the Properties menu items is selected
            propertiesmenuitem.addActionListener( new ActionListener() {
                    // We must keep a reference to object referenced by targetvertex,
                    // because after the popup() method is called, targertvertex is set to null
                    // and there will no way for the dialog to know which context is it
                    // displaying information for.
                    VisualVertex  selectedvertex = targetvertex;

                    public void actionPerformed( ActionEvent actionevent ) {
                        new VisualGraphComponentPropertiesDialog( gpanel,
                                                                 this.selectedvertex );
                        gpanel.repaint();
                    }
                });

            // For the Delete menu item, delete the vertex from the graph
            deletemenuitem.addActionListener( new ActionListener() {
                    // We must keep a reference to object referenced by targetvertex,
                    // because after the popup() method is called, targertvertex is set to null
                    // and there will no way for us to know which vertex to remove.
                    VisualVertex    nodetoremove = targetvertex;

                    public void actionPerformed( ActionEvent actionevent ) {
                        if( nodetoremove != null ) {
                            try {
                                gpanel.getVisualGraph().remove( this.nodetoremove );
                                gpanel.repaint();
                            }
                            catch( Exception ex )  {
                                ex.printStackTrace();
                                return;
                            }
                        }
                    }
                });

            popup.show( this.gpanel, x, y);
        }

        // Show a popup menu for an edge
        else if( this.targetedge != null ) {
            popup = new JPopupMenu();
            propertiesmenuitem = new JMenuItem( "Edge Properties..." );
            deletemenuitem = new JMenuItem( "Delete Edge" );

            popup.add( propertiesmenuitem );
            popup.addSeparator();
            popup.add( deletemenuitem );

            // Specify what action to take when the Properties menu items is selected
            propertiesmenuitem.addActionListener( new ActionListener() {
                    // We must keep a reference to object referenced by targetedge,
                    // because after the popup() method is called, targertedge is set to null
                    // and there will no way for the dialog to know which context is it
                    // displaying information for.
                    VisualEdge  selectededge = targetedge;

                    public void actionPerformed( ActionEvent actionevent ) {
                        new VisualGraphComponentPropertiesDialog( gpanel,
                                                                 selectededge );
                        gpanel.repaint();
                    }
                });

            // For the Delete menu item, delete the vertex from the graph
            deletemenuitem.addActionListener( new ActionListener() {
                    // We must keep a reference to object referenced by targetedge,
                    // because after the popup() method is called, targertedge is set to null
                    // and there will no way for us to know which edge to delete.
                    VisualEdge  edgetoremove = targetedge;

                    public void actionPerformed( ActionEvent actionevent ) {
                        if( edgetoremove != null ) {
                            try {
                                gpanel.getVisualGraph().removeEdge( edgetoremove );
                                gpanel.repaint();
                            }
                            catch( Exception ex ) {
                                ex.printStackTrace();
                                return;
                            }
                        }
                    }
                });
            popup.show( this.gpanel, x, y );
        }
    }

    /**
     * This method sets the cursor to a MOVE_CURSOR whenever the cursor
     * enters a VisualVertex object. The cursor is reset to its original
     * when the mouse cursor leaves a VisualVertex object.
     */
    public GraphPanelState mouseMoved( MouseEvent e ) {
        VisualGraphComponent    vVertex = this.gpanel.getVisualGraph().getNode( e.getX(), e.getY() );
        VisualGraphComponent    vEdge = this.gpanel.getVisualGraph().getVisualEdge( e.getX(), e.getY() );
        VisualGraphComponent    component;

        if( vVertex != null ) {
            if ( this.previouscursor == null )
                this.previouscursor = this.gpanel.getCursor();
            this.gpanel.setCursor( this.movecursor );
        }
        else {
            this.gpanel.setCursor( this.previouscursor );
            this.previouscursor = null;
        }

        // Notify the VisualGraphComponent of the event
        informTargetVisualGraphComponentOfMouseEvent(e);

        return this;

    }

    /**
     * Call VisualGraph.paint() method, passing the Graphics2D context
     * and the targetvertex
     */
    public void paint( Graphics2D g2d ) {
        this.gpanel.getVisualGraph().paint( g2d, this.targetvertex );
    }

}