如何在JPanel上画圆？Java 2D

Question

我有一个JPanel，我为此设置了一些图像作为背景。我需要在图像上方绘制一堆圆圈。现在，圆将基于某个坐标x，y进行定位，其大小将基于某个整数大小。这就是我上课的时间。

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.JPanel;

class ImagePanel extends JPanel {

    private Image img;
    CircleList cList;  //added this

    public ImagePanel(Image img) {
        this.img = img;
        Dimension size = new Dimension(img.getWidth(null), img.getHeight(null));
        setPreferredSize(size);
        setMinimumSize(size);
        setMaximumSize(size);
        setSize(size);
        setLayout(null);

        cList = new CircleList(); //added this
    }

    public void paintComponent(Graphics g) {
        g.drawImage(img, 0, 0, null);

        cList.draw(null); //added this
    }
}

如何创建可以执行此操作的方法？

Answer 1

您的方法可能与此类似，其中您也使用一个类CircleList来容纳所有圆和绘制例程：

class CircleList
{
  static class Circle
  {
    public float x, y, diameter;
  }

  ArrayList<Circle> circles;

  public CirclesList()
  {
    circles = new ArrayList<Circle>();
  }

  public void draw(Graphics2D g) // draw must be called by paintComponent of the panel
  {
    for (Circle c : circles)
      g.fillOval(c.x, c.y, c.diameter, c.diameter)
  }
}