ComplexExample.java Source code

Introduction

Here is the source code for ComplexExample.java

Source

import java.awt.Color;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DragGestureEvent;
import java.awt.dnd.DragGestureListener;
import java.awt.dnd.DragSource;
import java.awt.dnd.DropTarget;
import java.awt.dnd.DropTargetAdapter;
import java.awt.dnd.DropTargetDropEvent;

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

public class ComplexExample extends JFrame implements DragGestureListener {
    public ComplexExample() {
        JPanel left = new JPanel();
        left.setBackground(Color.red);

        JPanel right = new JPanel();
        right.setBackground(Color.white);

        new MyDropTargetListener(right);

        DragSource ds = new DragSource();
        ds.createDefaultDragGestureRecognizer(left, DnDConstants.ACTION_COPY, this);

        setLayout(new FlowLayout());
        add(left);
        add(right);

        setSize(40, 50);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);
    }

    public void dragGestureRecognized(DragGestureEvent event) {
        Cursor cursor = null;
        JPanel panel = (JPanel) event.getComponent();

        Color color = panel.getBackground();
        if (event.getDragAction() == DnDConstants.ACTION_COPY) {
            cursor = DragSource.DefaultCopyDrop;
        }
        event.startDrag(cursor, new TransferableColor(color));
    }

    class MyDropTargetListener extends DropTargetAdapter {
        private DropTarget dropTarget;
        private JPanel panel;

        public MyDropTargetListener(JPanel panel) {
            this.panel = panel;
            dropTarget = new DropTarget(panel, DnDConstants.ACTION_COPY, this, true, null);
        }

        public void drop(DropTargetDropEvent event) {
            try {
                Transferable tr = event.getTransferable();
                Color color = (Color) tr.getTransferData(TransferableColor.colorFlavor);
                if (event.isDataFlavorSupported(TransferableColor.colorFlavor)) {
                    event.acceptDrop(DnDConstants.ACTION_COPY);
                    this.panel.setBackground(color);
                    event.dropComplete(true);
                    return;
                }
                event.rejectDrop();
            } catch (Exception e) {
                e.printStackTrace();
                event.rejectDrop();
            }
        }
    }

    public static void main(String[] args) {
        new ComplexExample();
    }
}

class TransferableColor implements Transferable {
    protected static DataFlavor colorFlavor = new DataFlavor(Color.class, "A Color Object");
    protected static DataFlavor[] supportedFlavors = { colorFlavor };
    Color color;

    public TransferableColor(Color color) {
        this.color = color;
    }

    public DataFlavor[] getTransferDataFlavors() {
        return supportedFlavors;
    }

    public boolean isDataFlavorSupported(DataFlavor flavor) {
        if (flavor.equals(colorFlavor) || flavor.equals(DataFlavor.stringFlavor))
            return true;
        return false;
    }

    public Object getTransferData(DataFlavor flavor) throws UnsupportedFlavorException {
        if (flavor.equals(colorFlavor))
            return color;
        else if (flavor.equals(DataFlavor.stringFlavor))
            return color.toString();
        else
            throw new UnsupportedFlavorException(flavor);
    }
}