[Java画图]画函数图像

利用Graphics类画任意显式函数图像，只需修改代码中的F()函数即可，另外调整timesx和timesy参数来分方向放大或缩小图像。需要重定义坐标系。
  1 package test;
  2 
  3 import javax.swing.*;
  4 import java.awt.Graphics;
  5 
  6 public class DrawFunction extends JFrame {
  7     static double timesx = 10, timesy = 10;
  8     double F(double x) {
  9         return Math.sin(x) / Math.pow(1.1, -x);//函数表达式
 10     }
 11     int x0, y0;
 12     static int W = 800, H = 600;
 13     static double L = -W / 2, R = W / 2;
 14     Graphics G;
 15     public void setOrigin(int x, int y) {
 16         this.x0 = x;
 17         this.y0 = y;
 18         // show coordinate axis
 19         drawLine(-W / 2, 0, W / 2, 0);
 20         drawLine(0, -H / 2, 0, H / 2);
 21         drawString("X", W / 2 - 30, -20);
 22         drawString("Y", -20, H / 2 - 20);
 23         for (int i = 1; i <= 10; i ++) {
 24             draw(W / 2 - i - 6, i);
 25             draw(W / 2 - i - 6, -i);
 26         }
 27         for (int i = 1; i <= 10; i ++) {
 28             draw(-i, H / 2 - i);
 29             draw(i, H / 2 - i);
 30         }
 31     }
 32     public DrawFunction() {
 33         add(new NewPanel());
 34     }
 35     public static void main(String[] args) {
 36         DrawFunction frame = new DrawFunction();
 37         frame.setTitle("DrawFunction");
 38         frame.setSize(W, H);
 39         frame.setLocationRelativeTo(null);
 40         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 41         frame.setVisible(true);
 42         frame.setResizable(false);
 43     }
 44     public class Coordinate2D {
 45         int x, y;
 46         public Coordinate2D(int x, int y) {
 47             this.x = x;
 48             this.y = y;
 49         }
 50         public int getPixelPointX() {
 51             return x0 + x;
 52         }
 53         public int getPixelPointY() {
 54             return y0 - y;
 55         }
 56     }
 57     class NewPanel extends JPanel {
 58         protected void paintComponent(Graphics g) {
 59             super.paintComponent(g);
 60             G = g;
 61             setOrigin(W / 2, H / 2);
 62             // in the following , draw what you want draw!
 63             for (int i = -W / 2; i <= W / 2; i ++) {
 64                 draw(i, work(i));
 65             }
 66             /*
 67             for (int i = 0; i < 1000; i ++) {
 68                 int x = (int)(Math.random() * 400 - 200);
 69                 int y = (int)(Math.random() * 400 - 200);
 70                 drawString("哈哈", x, y);
 71             }
 72             */
 73         }
 74     }
 75     int work(int x) {
 76         //timesx = 0.01;
 77         //timesy = 100;
 78         return (int)(F(x / timesx) * timesy);
 79     }
 80     public void draw(int x, int y) {
 81         int X = new Coordinate2D(x, y).getPixelPointX();
 82         int Y = new Coordinate2D(x, y).getPixelPointY();
 83         G.drawLine(X, Y, X, Y);
 84     }
 85     public void drawRec(int x1, int y1, int x2, int y2) {
 86         int dx = x1 < x2? 1 : -1;
 87         int dy = y1 < y2? 1 : -1;
 88         for (int i = x1; i != x2 + dx; i += dx) {
 89             for (int j = y1; j != y2 + dy; j += dy) {
 90                 draw(i, j);
 91             }
 92         }
 93     }
 94     public void drawLine(int x1, int y1, int x2, int y2) {
 95         int dx = x1 < x2? 1 : -1;
 96         if (x1 == x2) drawRec(x1, y1, x2, y2);
 97         else {
 98             double d = (double)(y2 - y1) / (x2 - x1);
 99             for (int i = x1; i != x2 + dx; i += dx) {
100                 draw(i, (int)(y1 + (i - x1) * d));
101             }
102         }
103     }
104     public void drawString(String s, int x, int y) {
105         int X = new Coordinate2D(x, y).getPixelPointX();
106         int Y = new Coordinate2D(x, y).getPixelPointY();
107         G.drawString(s, X, Y);
108     }
109 }