GEF：使用Draw2D画流程图-（上）

在GEF（Graphical Editing Framework）介绍中已经对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：flowchart-Draw2D.zip

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
  

  01 public class TerminatorFigure extends ActivityFigure {
  02     FixedAnchor inAnchor, outAnchor;
  03
  04     public TerminatorFigure() {
  05         inAnchor = new FixedAnchor(this);
  06         inAnchor.place = new Point(1, 0);
  07         targetAnchors.put("in_term", inAnchor);
  08         outAnchor = new FixedAnchor(this);
  09         outAnchor.place = new Point(1, 2);
  10         sourceAnchors.put("out_term", outAnchor);
  11     }
  12
  13     public void paintFigure(Graphics g) {
  14         Rectangle r = bounds;
  15         g.drawArc(r.x + r.width / 8, r.y, r.width / 4, r.height - 1, 90, 180);
  16         g.drawLine(r.x + r.width / 4, r.y, r.x + 3 * r.width / 4, r.y);
  17         g.drawLine(r.x + r.width / 4, r.y + r.height - 1,
  18                 r.x + 3 * r.width / 4, r.y + r.height - 1);
  19         g.drawArc(r.x + 5 * r.width / 8, r.y, r.width / 4, r.height - 1, 270,
  20                 180);
  21         g.drawText(message, r.x + 3 * r.width / 8, r.y + r.height / 8);
  22     }
  23 }

• 分支图例
  

  01 public class DecisionFigure extends ActivityFigure {
  02     FixedAnchor inAnchor, yesAnchor, noAnchor;
  03
  04     public DecisionFigure() {
  05         inAnchor = new FixedAnchor(this);
  06         inAnchor.place = new Point(1, 0);
  07         targetAnchors.put("in_dec", inAnchor);
  08         noAnchor = new FixedAnchor(this);
  09         noAnchor.place = new Point(2, 1);
  10         sourceAnchors.put("no", noAnchor);
  11         yesAnchor = new FixedAnchor(this);
  12         yesAnchor.place = new Point(1, 2);
  13         sourceAnchors.put("yes", yesAnchor);
  14     }
  15
  16     public void paintFigure(Graphics g) {
  17         Rectangle r = bounds;
  18         PointList pl = new PointList(4);
  19         pl.addPoint(r.x + r.width / 2, r.y);
  20         pl.addPoint(r.x, r.y + r.height / 2);
  21         pl.addPoint(r.x + r.width / 2, r.y + r.height - 1);
  22         pl.addPoint(r.x + r.width, r.y + r.height / 2);
  23         g.drawPolygon(pl);
  24         g.drawText(message, r.x + r.width / 4 + 5, r.y + 3 * r.height / 8);
  25         g.drawText("N", r.x + 7 * r.width / 8, r.y + 3 * r.height / 8);
  26         g.drawText("Y", r.x + r.width / 2 - 2, r.y + 3 * r.height / 4);
  27     }
  28 }

• 流程图例
  

  01 public class ProcessFigure extends ActivityFigure {
  02     FixedAnchor inAnchor, outAnchor;
  03
  04     public ProcessFigure() {
  05         inAnchor = new FixedAnchor(this);
  06         inAnchor.place = new Point(1, 0);
  07         targetAnchors.put("in_proc", inAnchor);
  08         outAnchor = new FixedAnchor(this);
  09         outAnchor.place = new Point(1, 2);
  10         sourceAnchors.put("out_proc", outAnchor);
  11     }
  12
  13     public void paintFigure(Graphics g) {
  14         Rectangle r = bounds;
  15         g.drawText(message, r.x + r.width / 4, r.y + r.height / 4);
  16         g.drawRectangle(r.x, r.y, r.width - 1, r.height - 1);
  17     }
  18 }

• FixedAnchor：连接画线时会根据place来调用getLocation确定连接终点的位置
  

  01 public class FixedAnchor extends AbstractConnectionAnchor
  02 {
  03   Point place;
  04   public FixedAnchor(IFigure owner)
  05   {
  06     super(owner);
  07   }
  08
  09   public Point getLocation(Point loc)
  10   {
  11     Rectangle r = getOwner().getBounds();
  12     int x = r.x + place.x * r.width/2;
  13     int y = r.y + place.y * r.height/2;
  14     Point p = new PrecisionPoint(x,y);
  15     getOwner().translateToAbsolute(p);
  16     return p;
  17   }
  18 }

• ActivityFigure：主要处理连接点的代码