在SWT窗口中使用Draw2D绘制任意曲线

首先在工程中导入Draw2D包。

建立一个Java Project之后，在Package Explorer中右击工程名，选择下图所示菜单：

这样，工程下会出现一个META-INF文件夹，双击打开其中的.MF文件，选择Dependencies选项，在Required Plug-ins中单击Add...按钮，输入*.draw2d，添加draw2d后保存改.MF文件。

这样就可以使用Draw2D绘图了。

在工程下新建两个.java文件，分别如下：

DrawLineListener.java

import org.eclipse.draw2d.IFigure;
import org.eclipse.draw2d.MouseEvent;
import org.eclipse.draw2d.MouseListener;
import org.eclipse.draw2d.MouseMotionListener;
import org.eclipse.draw2d.PolylineConnection;
import org.eclipse.swt.SWT;
public class DrawLineListener extends MouseMotionListener.Stub implements MouseListener{
	PolylineConnection connection=null;
	IFigure figure;
	public void addDrawLineListener(IFigure figure){
		
		this.figure=figure;
		figure.addMouseMotionListener(this);
		figure.addMouseListener(this);
	}
	@Override
	public void mousePressed(MouseEvent me) {
		connection=new PolylineConnection();
		connection.setLineStyle(SWT.LINE_DOT);
		connection.removeAllPoints();
		connection.addPoint(me.getLocation());
		figure.add(connection);
	}
	@Override
	public void mouseReleased(MouseEvent me) {
		connection.setLineStyle(SWT.LINE_CUSTOM);
	}
	@Override
	public void mouseDoubleClicked(MouseEvent me) {
		// TODO Auto-generated method stub
		
	}
	public void mouseDragged(MouseEvent e) {
		connection.addPoint(e.getLocation());
	}
}

DrawLineFrame.java

import org.eclipse.draw2d.LightweightSystem;
import org.eclipse.draw2d.Panel;
import org.eclipse.draw2d.XYLayout;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class DrawLineFrame {

	protected Shell shell;
	public static void main(String[] args) {
		try {
			DrawLineFrame window = new DrawLineFrame();
			window.open();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	public void open() {
		Display display = Display.getDefault();
		createContents();
		shell.open();
		shell.layout();
		while (!shell.isDisposed()) {
			if (!display.readAndDispatch()) {
				display.sleep();
			}
		}
	}
	protected void createContents() {
		shell = new Shell();
		shell.setSize(400, 300);;
		shell.setText("画线演示");
		Panel panel = new Panel();
		panel.setLayoutManager(new XYLayout());
		DrawLineListener drawLine=new DrawLineListener();
		drawLine.addDrawLineListener(panel);
		LightweightSystem lws = new LightweightSystem(shell);
		lws.setContents(panel);
	}
}

运行结果如下：

上图中松开鼠标后，虚线变成实线。