Question

用java怎样画椭圆？

Answer 1

你的问题是是使用java画椭圆，可洞裂以使用awt和swing类库实现
画椭圆可以通过画矩形及其内切椭圆实现，示例代码如纳茄闭下
如果纳斗只需要椭圆，则无需g2.draw(rect);
class DrawPanel extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
// 画矩形
double leftX = 100;
double topY = 100;
double width = 200;
double height = 150;
Rectangle2D rect = new Rectangle2D.Double(leftX, topY, width, height);
g2.draw(rect);
// 画rect的内切椭圆
Ellipse2D ellipse = new Ellipse2D.Double();
ellipse.setFrame(rect);
g2.draw(ellipse);
}
}

Answer 2

用 drawOval(int x,int y,int w,int h); x,y代表敬森坐标 w,h代表宽度和高度 比如
drawOval(50,50,50,100);这是一个椭闷悄形,
drawOval(50,50,50,50); 这是亮罩亩一个圆形.

Answer 3

    
    public void actionPerformed(ActionEvent e)
    {
        
      if(e.getActionCommand().equals("椭圆"))
        {
            paintFlag=2;
        }
          
    }
    
    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);            
        }
        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();
   晌物 }
    
    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))
        {
            宴拿液newX1=x2;newY1=y2;
            newX2=x1;newY2=y1;
        }
        else if((x1>x2) && (y1<y2))
        {
            newX1=x2;newY1=y1;
            newX2=x1;newY2=y2;
        }
    }    敏判
}