Java中的绘制矩形

Question

我正在尝试绘制一个矩形。但我不确定如何在特定面板上绘画。想看一个例子，我如何提供绘制矩形的面板和位置。我有以下模板，我想看看要使用该类在任何面板上绘制矩形需要进行哪些修改。我的意图是使用面板的宽度和高度，并在该位置添加一个矩形。目标是能够在任何具有JPanel的任何地方使用此类。

import java.awt.Color;
import java.awt.Graphics;    
import javax.swing.JPanel;    

public class DrawRectangle{

    private int startX;
    private int startY;
    private int width;
    private int height;
    private Color color;
    private JPanel panel;

    public DrawRectangle(JPanel panel, int startX, int startY, int width, int height, Color color) {
        this.startX = startX;
        this.startY = startY;
        this.width = width;
        this.height = height;
        this.color = color;
            this.panel = panel; 
    }

    public void paint(Graphics g) {
        g.setColor(this.color);
        g.fillRect(this.startX, this.startY, this.width, this.height);
        g.drawRect(this.startX, this.startY, this.width, this.height);
    }
}

Answer 1

您必须修改感兴趣的JPanel才能通过以下方式使用该代码：

• 覆盖其paintComponent方法
• 首先在您的覆盖中调用上级的paintComponent方法
• 然后绘制您自己的DrawRectangle类的paint方法
• 如果您希望能够绘制多个矩形，则给JPanel一个ArrayList<DrawRectangle>并在paintComponent的for循环中绘制它们。>

例如，对于一个矩形：

public class DrawingPanel extends JPanel {
    private DrawRectangle drawRectangle;

    public DrawingPanel(DrawRectangle drawRectangle) {
        this.drawRectangle = drawRectangle;
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (drawRectangle != null) {
            drawRectangle.paint(g);
        }
    }
}
并且对于许多矩形：

public class DrawingManyRectPanel extends JPanel {
    private List<DrawRectangle> drawRectangles;

    public DrawingManyRectPanel(List<DrawRectangle> drawRectangles) {
        this.drawRectangles = drawRectangles;
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (drawRectangles != null) {
            for (DrawRectangle rectangle : drawRectangles) {
                rectangle.paint(g);
            }
        }
    }
}
在这些类中，重写了构造函数，以允许通过构造函数调用将矩形注入到该类中。对于第二个类，我还将添加一个方法，该方法允许添加其他矩形：

public void addRectangle(DrawRectangle rectangle) {
    drawRectangles.add(rectangle);
    repaint();
}
类似于删除矩形