在中已经对Draw2D进行了一些概要介绍，本篇从一个流程图的编写来学习Draw2D的是GEF的基础。

练习要求

做一个图下图所示流程图，流程图中的各个图例可以移动，每个不同类型的图例也不一样。 源码下载：

基础概念

 

 

图例Figure

这里支持三种图例，图例从ActivityFigure继承下来。主要就是画图还有定义连接点FixedAnchor，下面先看看代码，代码都比较简单

• 开始、结束图例
  public class TerminatorFigure extends ActivityFigure {	FixedAnchor inAnchor, outAnchor;	public TerminatorFigure() {		inAnchor = new FixedAnchor(this);		inAnchor.place = new Point(1, 0);		targetAnchors.put("in_term", inAnchor);		outAnchor = new FixedAnchor(this);		outAnchor.place = new Point(1, 2);		sourceAnchors.put("out_term", outAnchor);	}	public void paintFigure(Graphics g) {		Rectangle r = bounds;		g.drawArc(r.x + r.width / 8, r.y, r.width / 4, r.height - 1, 90, 180);		g.drawLine(r.x + r.width / 4, r.y, r.x + 3 * r.width / 4, r.y);		g.drawLine(r.x + r.width / 4, r.y + r.height - 1,				r.x + 3 * r.width / 4, r.y + r.height - 1);		g.drawArc(r.x + 5 * r.width / 8, r.y, r.width / 4, r.height - 1, 270,				180);		g.drawText(message, r.x + 3 * r.width / 8, r.y + r.height / 8);	}}
• 分支图例
  public class DecisionFigure extends ActivityFigure {	FixedAnchor inAnchor, yesAnchor, noAnchor;	public DecisionFigure() {		inAnchor = new FixedAnchor(this);		inAnchor.place = new Point(1, 0);		targetAnchors.put("in_dec", inAnchor);		noAnchor = new FixedAnchor(this);		noAnchor.place = new Point(2, 1);		sourceAnchors.put("no", noAnchor);		yesAnchor = new FixedAnchor(this);		yesAnchor.place = new Point(1, 2);		sourceAnchors.put("yes", yesAnchor);	}	public void paintFigure(Graphics g) {		Rectangle r = bounds;		PointList pl = new PointList(4);		pl.addPoint(r.x + r.width / 2, r.y);		pl.addPoint(r.x, r.y + r.height / 2);		pl.addPoint(r.x + r.width / 2, r.y + r.height - 1);		pl.addPoint(r.x + r.width, r.y + r.height / 2);		g.drawPolygon(pl);		g.drawText(message, r.x + r.width / 4 + 5, r.y + 3 * r.height / 8);		g.drawText("N", r.x + 7 * r.width / 8, r.y + 3 * r.height / 8);		g.drawText("Y", r.x + r.width / 2 - 2, r.y + 3 * r.height / 4);	}}
• 流程图例
  public class ProcessFigure extends ActivityFigure {	FixedAnchor inAnchor, outAnchor;	public ProcessFigure() {		inAnchor = new FixedAnchor(this);		inAnchor.place = new Point(1, 0);		targetAnchors.put("in_proc", inAnchor);		outAnchor = new FixedAnchor(this);		outAnchor.place = new Point(1, 2);		sourceAnchors.put("out_proc", outAnchor);	}	public void paintFigure(Graphics g) {		Rectangle r = bounds;		g.drawText(message, r.x + r.width / 4, r.y + r.height / 4);		g.drawRectangle(r.x, r.y, r.width - 1, r.height - 1);	}}
• FixedAnchor：连接画线时会根据place来调用getLocation确定连接终点的位置
  public class FixedAnchor extends AbstractConnectionAnchor{  Point place;  public FixedAnchor(IFigure owner)  {    super(owner);  }    public Point getLocation(Point loc)  {    Rectangle r = getOwner().getBounds();    int x = r.x + place.x * r.width/2;    int y = r.y + place.y * r.height/2;    Point p = new PrecisionPoint(x,y);    getOwner().translateToAbsolute(p);    return p;  }}
• ActivityFigure：主要处理连接点的代码
  abstract public class ActivityFigure extends Figure {	Rectangle r = new Rectangle();	Hashtable targetAnchors = new Hashtable();	Hashtable sourceAnchors = new Hashtable();	String message = new String();	public void setName(String msg) {		message = msg;		repaint();	}	public ConnectionAnchor ConnectionAnchorAt(Point p) {		ConnectionAnchor closest = null;		long min = Long.MAX_VALUE;		Hashtable conn = getSourceConnectionAnchors();		conn.putAll(getTargetConnectionAnchors());		Enumeration e = conn.elements();		while (e.hasMoreElements()) {			ConnectionAnchor c = (ConnectionAnchor) e.nextElement();			Point p2 = c.getLocation(null);			long d = p.getDistance2(p2);			if (d < min) {				min = d;				closest = c;			}		}		return closest;	}	public ConnectionAnchor getSourceConnectionAnchor(String name) {		return (ConnectionAnchor) sourceAnchors.get(name);	}	public ConnectionAnchor getTargetConnectionAnchor(String name) {		return (ConnectionAnchor) targetAnchors.get(name);	}	public String getSourceAnchorName(ConnectionAnchor c) {		Enumeration
         
           keys = sourceAnchors.keys();		String name;		while (keys.hasMoreElements()) {			name = (String) keys.nextElement();			if (sourceAnchors.get(name).equals(c))				return name;		}		return null;	}	public String getTargetAnchorName(ConnectionAnchor c) {		Enumeration
          
            keys = targetAnchors.keys();		String name = null;		while (keys.hasMoreElements()) {			name = (String) keys.nextElement();			if (targetAnchors.get(name).equals(c))				return name;		}		return null;	}	public ConnectionAnchor getSourceConnectionAnchorAt(Point p) {		ConnectionAnchor closest = null;		long min = Long.MAX_VALUE;		Enumeration e = getSourceConnectionAnchors().elements();		while (e.hasMoreElements()) {			ConnectionAnchor c = (ConnectionAnchor) e.nextElement();			Point p2 = c.getLocation(null);			long d = p.getDistance2(p2);			if (d < min) {				min = d;				closest = c;			}		}		return closest;	}	public Hashtable getSourceConnectionAnchors() {		return sourceAnchors;	}	public ConnectionAnchor getTargetConnectionAnchorAt(Point p) {		ConnectionAnchor closest = null;		long min = Long.MAX_VALUE;		Enumeration e = getTargetConnectionAnchors().elements();		while (e.hasMoreElements()) {			ConnectionAnchor c = (ConnectionAnchor) e.nextElement();			Point p2 = c.getLocation(null);			long d = p.getDistance2(p2);			if (d < min) {				min = d;				closest = c;			}		}		return closest;	}	public Hashtable getTargetConnectionAnchors() {		return targetAnchors;	}}
          
         

连接点PathFigure

连接点从PolylineConnection继承下来，在构造函数中设置目标对象连接点的装饰类，也就是示例中的三角形（PolylineDecoration），以及设定连接线路由样式，这里设置为ManhattanConnectionRouter

 

public class PathFigure extends PolylineConnection {	public PathFigure() {		//setSourceDecoration(new PolygonDecoration());		setTargetDecoration(new PolylineDecoration());		//setConnectionRouter(new BendpointConnectionRouter());		setConnectionRouter(new ManhattanConnectionRouter());					}}

监听移动事件

 

public class Dnd extends MouseMotionListener.Stub implements MouseListener {	public Dnd(IFigure figure) {		figure.addMouseMotionListener(this);		figure.addMouseListener(this);	}	Point start;	public void mouseReleased(MouseEvent e) {	}	public void mouseClicked(MouseEvent e) {	}	public void mouseDoubleClicked(MouseEvent e) {	}	public void mousePressed(MouseEvent e) {		start = e.getLocation();	}	public void mouseDragged(MouseEvent e) {		Point p = e.getLocation();		Dimension d = p.getDifference(start);		start = p;		Figure f = ((Figure) e.getSource());		f.setBounds(f.getBounds().getTranslated(d.width, d.height));	}}

 

Flowchart

Flowchart是主程序代码，生成最上图所示的所有图例、连接，并把连接于连接点关联起来，并加入监听移动事件对象

 

public class Flowchart {	public static void main(String args[]) {		Shell shell = new Shell();		shell.setSize(300, 400);		shell.open();		shell.setText("Flowchart");		LightweightSystem lws = new LightweightSystem(shell);		ChartFigure flowchart = new ChartFigure();		lws.setEventDispatcher(new SWTEventDispatcherX(1800000L));				lws.setContents(flowchart);		TerminatorFigure start = new TerminatorFigure();		start.setName("Start");		start.setToolTip(new Label("起点"));		start.setBounds(new Rectangle(40, 20, 80, 20));		DecisionFigure dec = new DecisionFigure();		dec.setName("Should I?");		dec.setBounds(new Rectangle(30, 60, 100, 60));		ProcessFigure proc = new ProcessFigure();		proc.setName("Do it!");		proc.setToolTip(new Button("do it"));				proc.setBounds(new Rectangle(40, 140, 80, 40));		TerminatorFigure stop = new TerminatorFigure();		stop.setName("End");		stop.setBounds(new Rectangle(140, 300, 80, 20));		PathFigure path1 = new PathFigure();		path1.setSourceAnchor(start.outAnchor);		path1.setTargetAnchor(dec.inAnchor);		PathFigure path2 = new PathFigure();		path2.setSourceAnchor(dec.yesAnchor);		path2.setTargetAnchor(proc.inAnchor);		PathFigure path3 = new PathFigure();		path3.setSourceAnchor(dec.noAnchor);		path3.setTargetAnchor(stop.inAnchor);		PathFigure path4 = new PathFigure();		path4.setSourceAnchor(proc.outAnchor);		path4.setTargetAnchor(stop.inAnchor);		flowchart.add(start);		flowchart.add(dec);		flowchart.add(proc);		flowchart.add(stop);		flowchart.add(path1);		flowchart.add(path2);		flowchart.add(path3);		flowchart.add(path4);		new Dnd(start);		new Dnd(proc);		new Dnd(dec);		new Dnd(stop);		Display display = Display.getDefault();		while (!shell.isDisposed()) {			if (!display.readAndDispatch())				display.sleep();		}	}}

 

参考：

 

 

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