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
  
  view source print ?

  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
  
  view source print ?

  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
  
  view source print ?

  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
  
  view source print ?

  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