Java关于图形坐标的问题

Question

如果我创建一个 800x600 像素的 JFrame 并从 (0,0) 到 (800,600) 画一条线，它不会从一个角到另一个角，所以 (0,0) 和 (800,600) 在哪里)？这是代码

import java.awt.Graphics;

import javax.swing.JFrame;

public class Point0_0test extends JFrame {

    public Point0_0test() {
        setTitle("Test");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(800, 600);
        setLocationRelativeTo(null);
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
        g.drawLine(0, 0, 800, 600);
    }

    public static void main(String[] args) {
        Point0_0test test = new Point0_0test();
        test.setVisible(true);
    }

}

Here you can see what appears when the program is running

Answer 1

如果您想要 800 x 600 像素的绘图区域，请设置 800 x 600 像素的绘图区域。谁在乎框架有多大？

这是我创建的一个简单的绘图 GUI。我将其设置为 400 x 300 像素，以便它更容易适合答案。

这是代码。这是一个最小的、可运行的示例，用于设置绘图区域的大小。

import java.awt.BasicStroke;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class SimpleDrawingArea implements Runnable {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new SimpleDrawingArea());
    }

    @Override
    public void run() {
        JFrame frame = new JFrame("Simple Drawing Panel");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new DrawingPanel());
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public class DrawingPanel extends JPanel {

        private static final long serialVersionUID = 1L;

        public DrawingPanel() {
            this.setPreferredSize(new Dimension(400, 300));
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g;
            g2d.setStroke(new BasicStroke(4f));
            g2d.drawLine(0, 0, 400, 300);
        }

    }

}