/*
 * A simple Java program that demonstrates how drag and drop works
 *
 * Ben Bederson, May 3, 2002
 */

import java.awt.datatransfer.*;
import java.awt.dnd.*;
import javax.swing.*;
import javax.swing.text.*;

public class DragAndDropExample extends CopyPasteExample {
    public DragAndDropExample() {
	new DragSourceExample(this);
	new DropTargetExample(this);
    }

    public JTextArea getTextArea() {
	return textArea;
    }

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

class DragSourceExample implements DragGestureListener, DragSourceListener {
    DragAndDropExample dndexample;

    DragSourceExample(DragAndDropExample dndexample) {
	this.dndexample = dndexample;

	DragSource dragSource = DragSource.getDefaultDragSource();
	dragSource.createDefaultDragGestureRecognizer(dndexample.getTextArea(),
						      DnDConstants.ACTION_COPY, this);
    }

    public synchronized void dragGestureRecognized(DragGestureEvent dge) {
	// This is buggy because it really should only start dragging
	// if something is selected and you clicked on the selection - 
	// but that is hard to do in this case since JTextArea deals with
	// the event handlers for you...
	Transferable transferable = dndexample.copy();
	dge.startDrag(DragSource.DefaultCopyDrop, transferable, this);
    }

    public void dropActionChanged(DragSourceDragEvent e){}

    public void dragEnter(DragSourceDragEvent e) {
    }

    public void dragOver(DragSourceDragEvent dsde) {
    }

    public void dragExit(DragSourceEvent dse) {
    }

    public void dragDropEnd(DragSourceDropEvent dsde) {
    }
}

class DropTargetExample implements DropTargetListener {
    DragAndDropExample dndexample;
    DropTarget dropTarget;
    boolean acceptableType;
    
    DropTargetExample(DragAndDropExample dndexample) {
	this.dndexample = dndexample;

	dropTarget = new DropTarget(dndexample.getTextArea(), this);
    }

    public void dragOver(DropTargetDragEvent e) {
	if (!acceptableType) {
	    e.rejectDrag();
	    return;
	}
    }

    public void dropActionChanged(DropTargetDragEvent e) {
    }

    public void dragExit(DropTargetEvent e) {
    }

    public void drop(DropTargetDropEvent e) {
	if (!acceptableType) {
	    e.rejectDrop();
	    return;
	}

	e.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
	Transferable transferable = e.getTransferable();
	dndexample.paste(transferable);
	e.dropComplete(true);
    }

    public void dragEnter(DropTargetDragEvent e) {
	DataFlavor[] flavors = e.getCurrentDataFlavors();
	DataFlavor flavor = null;
	for (int i=0; i<flavors.length; i++) {
	    if (flavors[i].getMimeType().startsWith("text/plain") &&
		flavors[i].getRepresentationClass().toString().indexOf("java.io.InputStream") != -1) {
		flavor = flavors[i];
		break;
	    }
	}
	if (flavor == null) {
	    flavor = DataFlavor.stringFlavor;
	}

	acceptableType = e.isDataFlavorSupported(flavor);

	if (acceptableType) {
	    e.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);
	} else {
	    e.rejectDrag();
	}
    }
}