Java画图板简单程序

import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.awt.geom.*; public class ToolBarListener extends MouseAdapter implements ActionListener,MouseMotionListener { private JPanel paintPanel=null; private static int paintFlag=-1; private double x1,y1,x2,y2; private double newX1,newY1,newX2,newY2; private Shape shape; public ToolBarListener(JPanel panel) { this.paintPanel=panel; } public void actionPerformed(ActionEvent e) { if(e.getActionCommand().equals("直线")) { paintFlag=1; } else if(e.getActionCommand().equals("椭圆")) { paintFlag=2; } else if(e.getActionCommand().equals("矩形")) { paintFlag=3; } } public void mousePressed(MouseEvent e) { x1=e.getX(); y1=e.getY(); } public void mouseDragged(MouseEvent e) { x2=e.getX(); y2=e.getY(); if(paintFlag==-1) { shape=new Line2D.Double(x1,y1,x2,y2); } if(paintFlag==1) { shape=new Line2D.Double(x1,y1,x2,y2); } else if(paintFlag==2) { coordinateChange(); shape=new Ellipse2D.Double(newX1,newY1,newX2-newX1,newY2-newY1); } else if(paintFlag==3) { coordinateChange(); shape=new Rectangle2D.Double(newX1,newY1,newX2-newX1,newY2-newY1); } ((PaintPanel)paintPanel).setShape(shape); ((PaintPanel)paintPanel).repaint(); } public void mouseMoved(MouseEvent e) { } public void mouseReleased(MouseEvent e) { ((PaintPanel)paintPanel).addShape(shape); ((PaintPanel)paintPanel).repaint(); } private void coordinateChange() { if((x1<x2) && (y1<y2)) { newX1=x1;newY1=y1; newX2=x2;newY2=y2; } if((x1<x2) && (y1>y2)) { newX1=x1;newY1=y2; newX2=x2;newY2=y1; } else if((x1>x2) && (y1>y2)) { newX1=x2;newY1=y2; newX2=x1;newY2=y1; } else if((x1>x2) && (y1<y2)) { newX1=x2;newY1=y1; newX2=x1;newY2=y2; } } }