流浪地球2 影评

看过电影全方位无死角的感觉很好，我就画一面国旗表达一下此刻的心情吧。

package com.gzz;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.Toolkit;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.AffineTransform;
import java.awt.geom.GeneralPath;
import javax.swing.JFrame;

public class RedFlag extends JFrame {
    private static final long serialVersionUID = 1L;
    private static final Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
    private static final double maxR = 0.15, minR = 0.05;
    private static final double maxX = 0.25, maxY = 0.25;
    private static final double[] minX = { 0.50, 0.60, 0.60, 0.50 };
    private static final double[] minY = { 0.10, 0.20, 0.35, 0.45 };

    public static void main(String[] args) {
        RedFlag redFlag = new RedFlag();
        redFlag.addMouseListener(new MouseAdapter() {
            public void mouseClicked(MouseEvent e) {
                System.exit(0);
            }
        });
        redFlag.setUndecorated(true);
        redFlag.setExtendedState(JFrame.MAXIMIZED_BOTH);
        redFlag.setVisible(true);
    }

    @Override
    public void paint(Graphics g) {
        Graphics2D graphics2D = (Graphics2D) g;
        graphics2D.setPaint(Color.RED);
        graphics2D.fillRect(0, 0, screen.width, screen.height);// 画旗面
        double ox = screen.height * maxX, oy = screen.height * maxY;
        graphics2D.setPaint(Color.YELLOW);
        graphics2D.fill(createPentacle(ox, oy, screen.height * maxR, -Math.PI / 2));// 画大☆
        for (int i = 0; i < 4; i++) {// 画小★
            double sx = minX[i] * screen.height, sy = minY[i] * screen.height;
            double theta = Math.atan2(oy - sy, ox - sx);
            graphics2D.fill(createPentacle(sx, sy, screen.height * minR, theta));
        }
    }

    /**
     * 创建一个五角星形状. 该五角星的中心坐标为(sx,sy),中心到顶点的距离为radius,其中某个顶点与中心的连线的偏移角度为theta(弧度)
     */
    private Shape createPentacle(double sx, double sy, double radius, double theta) {
        final double arc = Math.PI / 5;
        final double rad = Math.sin(Math.PI / 10) / Math.sin(3 * Math.PI / 10);
        GeneralPath path = new GeneralPath();
        path.moveTo(1, 0);
        for (int i = 0; i < 5; i++) {
            path.lineTo(rad * Math.cos((1 + 2 * i) * arc), rad * Math.sin((1 + 2 * i) * arc));
            path.lineTo(Math.cos(2 * (i + 1) * arc), Math.sin(2 * (i + 1) * arc));
        }
        path.closePath();
        AffineTransform atf = AffineTransform.getScaleInstance(radius, radius);
        atf.translate(sx / radius, sy / radius);
        atf.rotate(theta);
        return atf.createTransformedShape(path);
    }

}

五星红旗

这里用了大量三角函数，弧度，角度，平面坐标系，为了教会上小学三年级的儿子画国旗，于是我把程序简化了一下。

package com.gzz.common.base;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Toolkit;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
public class RedFlag2 extends JFrame {
    private static final long serialVersionUID = 1L;
    private static final Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
    private static final int scale = screen.width / 50;
    public static void main(String[] args) {
        RedFlag2 redFlag = new RedFlag2();
        redFlag.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.exit(0);// 单击退出
            }
        });
        redFlag.setUndecorated(true);// 隐藏标题栏
        redFlag.setExtendedState(JFrame.MAXIMIZED_BOTH);// 最大化
        redFlag.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        redFlag.setVisible(true);
    }
    @Override
    public void paint(Graphics g) {
        Graphics2D graphic = (Graphics2D) g;
        graphic.setPaint(Color.RED);
        graphic.fillRect(0, 0, screen.width, screen.height);// 画旗面
        graphic.setPaint(Color.YELLOW);
        // 画大星
        graphic.setFont(new Font("宋体", Font.BOLD, scale * 8));
        graphic.drawString("★", scale * 4, scale * 11);
        // 画小星
        graphic.setFont(new Font("宋体", Font.BOLD, scale * 3));
        graphic.drawString("★", scale * 11, scale * 4);
        graphic.setFont(new Font("宋体", Font.BOLD, scale * 3));
        graphic.drawString("★", scale * 14, scale * 8);
        graphic.setFont(new Font("宋体", Font.BOLD, scale * 3));
        graphic.drawString("★", scale * 14, scale * 12);
        graphic.setFont(new Font("宋体", Font.BOLD, scale * 3));
        graphic.drawString("★", scale * 11, scale * 16);
    }
}