我想画一个具有以下属性的圆:
中心是用户首先在窗口上单击鼠标的位置
半径应为首次单击鼠标与释放鼠标之间(即鼠标拖动)之间的距离的长度。
到目前为止,这是我所拥有的,但是它没有做我需要做的事情:
package assignment;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.*;
public class DrawCircle extends JFrame implements MouseListener
{
private int centerX;
private int centerY;
private int endPtX;
private int endPtY;
private double radius;
private double w;
private double h;
private CirclePanel circPanel;
/** constructor **/
public DrawCircle()
{
this.setTitle("Click to Draw Circle");
this.setSize(500, 500);
this.setPreferredSize(new Dimension(500, 500));
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
this.setResizable(false);
this.addMouseListener(this);
this.circPanel = new CirclePanel();
this.circPanel.setPreferredSize(new Dimension(500, 500));
this.add(this.circPanel);
pack();
}
public void mousePressed(MouseEvent e)
{
centerX = e.getX();
centerY = e.getY();
circPanel.set(centerX, centerY, radius, radius);
repaint();
pack();
}
public void mouseReleased(MouseEvent e)
{
endPtX = e.getX();
endPtY = e.getY();
radius = Math.sqrt(Math.pow(endPtX - centerX, 2) + Math.pow(endPtY - centerY, 2));
}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
public void mouseClicked(MouseEvent e){}
//circle panel
private class CirclePanel extends JComponent
{
private int x;
private int y;
private int w;
private int h;
public void set(int x, int y, double width, double height)
{
this.x = x;
this.y = y;
w = (int) width;
h = (int) height;
}
public void paintComponent(Graphics g)
{
g.drawOval(x, y, w, h);
}
}
//main method
public static void main (String [] args)
{
new DrawCircle();
}
}
最佳答案
看来您正在
circPanel.set(centerX, centerY, radius, radius);
repaint();
pack();
在错误的位置上,您不应该绘制圆,直到用户放开鼠标为止,因为那是在设置半径时且在半径为0之前,因此没有绘制任何内容。尝试将其移至
mouseReleased
方法。