Ptidej-v5.2-master/PADL Serialiser DB4O Tests/rsc/JHotDraw v5.1/src/CH/ifa/draw/standard/SelectionTool.java
/*
 * @(#)SelectionTool.java 5.1
 *
 */

package CH.ifa.draw.standard;

import java.awt.event.MouseEvent;

import CH.ifa.draw.framework.DrawingView;
import CH.ifa.draw.framework.Figure;
import CH.ifa.draw.framework.Handle;
import CH.ifa.draw.framework.Tool;

/**
 * Tool to select and manipulate figures.
 * A selection tool is in one of three states, e.g., background
 * selection, figure selection, handle manipulation. The different
 * states are handled by different child tools.
 * <hr>
 * <b>Design Patterns</b><P>
 * <img src="images/red-ball-small.gif" width=6 height=6 alt=" o ">
 * <b><a href=../pattlets/sld032.htm>State</a></b><br>
 * SelectionTool is the StateContext and child is the State.
 * The SelectionTool delegates state specific
 * behavior to its current child tool.
 * <hr>
 */

public class SelectionTool extends AbstractTool {

	private Tool fChild = null;

	public SelectionTool(DrawingView view) {
		super(view);
	}

	/**
	 * Handles mouse down events and starts the corresponding tracker.
	 */
	public void mouseDown(MouseEvent e, int x, int y)
	{
		// on Windows NT: AWT generates additional mouse down events
		// when the left button is down && right button is clicked.
		// To avoid dead locks we ignore such events
		if (fChild != null)
			return;

		view().freezeView();

		Handle handle = view().findHandle(e.getX(), e.getY());
		if (handle != null) {
			fChild = createHandleTracker(view(), handle);
		}
		else {
			Figure figure = drawing().findFigure(e.getX(), e.getY());
			if (figure != null) {
				fChild = createDragTracker(view(), figure);
			}
			else {
				if (!e.isShiftDown()) {
					view().clearSelection();
				}
				fChild = createAreaTracker(view());
			}
		}
		fChild.mouseDown(e, x, y);
	}

	/**
	 * Handles mouse drag events. The events are forwarded to the
	 * current tracker.
	 */
	public void mouseDrag(MouseEvent e, int x, int y) {
		if (fChild != null) // JDK1.1 doesn't guarantee mouseDown, mouseDrag, mouseUp
			fChild.mouseDrag(e, x, y);
	}

	/**
	 * Handles mouse up events. The events are forwarded to the
	 * current tracker.
	 */
	public void mouseUp(MouseEvent e, int x, int y) {
		view().unfreezeView();
		if (fChild != null) // JDK1.1 doesn't guarantee mouseDown, mouseDrag, mouseUp
			fChild.mouseUp(e, x, y);
		fChild = null;
	}

	/**
	 * Factory method to create a Handle tracker. It is used to track a handle.
	 */
	protected Tool createHandleTracker(DrawingView view, Handle handle) {
		return new HandleTracker(view, handle);
	}

	/**
	 * Factory method to create a Drag tracker. It is used to drag a figure.
	 */
	protected Tool createDragTracker(DrawingView view, Figure f) {
		return new DragTracker(view, f);
	}

	/**
	 * Factory method to create an area tracker. It is used to select an
	 * area.
	 */
	protected Tool createAreaTracker(DrawingView view) {
		return new SelectAreaTracker(view);
	}
}
