package test;

 import javax.swing.*;

 import java.awt.Graphics;

 public class DrawFunction extends JFrame {

     static double timesx = 10, timesy = 10;

     double F(double x) {

         return Math.sin(x) / Math.pow(1.1, -x);//函数表达式

     }

     int x0, y0;

     static int W = 800, H = 600;

     static double L = -W / 2, R = W / 2;

     Graphics G;

     public void setOrigin(int x, int y) {

         this.x0 = x;

         this.y0 = y;

         // show coordinate axis

         drawLine(-W / 2, 0, W / 2, 0);

         drawLine(0, -H / 2, 0, H / 2);

         drawString("X", W / 2 - 30, -20);

         drawString("Y", -20, H / 2 - 20);

         for (int i = 1; i <= 10; i ++) {

             draw(W / 2 - i - 6, i);

             draw(W / 2 - i - 6, -i);

         }

         for (int i = 1; i <= 10; i ++) {

             draw(-i, H / 2 - i);

             draw(i, H / 2 - i);

         }

     }

     public DrawFunction() {

         add(new NewPanel());

     }

     public static void main(String[] args) {

         DrawFunction frame = new DrawFunction();

         frame.setTitle("DrawFunction");

         frame.setSize(W, H);

         frame.setLocationRelativeTo(null);

         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

         frame.setVisible(true);

         frame.setResizable(false);

     }

     public class Coordinate2D {

         int x, y;

         public Coordinate2D(int x, int y) {

             this.x = x;

             this.y = y;

         }

         public int getPixelPointX() {

             return x0 + x;

         }

         public int getPixelPointY() {

             return y0 - y;

         }

     }

     class NewPanel extends JPanel {

         protected void paintComponent(Graphics g) {

             super.paintComponent(g);

             G = g;

             setOrigin(W / 2, H / 2);

             // in the following , draw what you want draw!

             for (int i = -W / 2; i <= W / 2; i ++) {

                 draw(i, work(i));

             }

             /*

             for (int i = 0; i < 1000; i ++) {

                 int x = (int)(Math.random() * 400 - 200);

                 int y = (int)(Math.random() * 400 - 200);

                 drawString("哈哈", x, y);

             }

             */

         }

     }

     int work(int x) {

         //timesx = 0.01;

         //timesy = 100;

         return (int)(F(x / timesx) * timesy);

     }

     public void draw(int x, int y) {

         int X = new Coordinate2D(x, y).getPixelPointX();

         int Y = new Coordinate2D(x, y).getPixelPointY();

         G.drawLine(X, Y, X, Y);

     }

     public void drawRec(int x1, int y1, int x2, int y2) {

         int dx = x1 < x2? 1 : -1;

         int dy = y1 < y2? 1 : -1;

         for (int i = x1; i != x2 + dx; i += dx) {

             for (int j = y1; j != y2 + dy; j += dy) {

                 draw(i, j);

             }

         }

     }

     public void drawLine(int x1, int y1, int x2, int y2) {

         int dx = x1 < x2? 1 : -1;

         if (x1 == x2) drawRec(x1, y1, x2, y2);

         else {

             double d = (double)(y2 - y1) / (x2 - x1);

             for (int i = x1; i != x2 + dx; i += dx) {

                 draw(i, (int)(y1 + (i - x1) * d));

             }

         }

     }

     public void drawString(String s, int x, int y) {

         int X = new Coordinate2D(x, y).getPixelPointX();

         int Y = new Coordinate2D(x, y).getPixelPointY();

         G.drawString(s, X, Y);

     }

 }