java 基础二 Graphics类

一、处理图形

1.画直线

void drawLine (int startx , int starty , int endx , int endy)

参数列表：直线开始的横坐标、纵坐标，直线结束的横坐标、纵坐标。

2.画矩形

1) 矩形边框：void drawRect(int top , int left , int width , int height )

2) 实心矩形 :void fillRect(int top , int left , int width , int height)

参数列表：矩形的左上角坐标(x,y)，宽度和高度。

3.圆角矩形

1) 圆角矩形边框 ： void drawRoundRect(int top , int left , int width , int height , int xDiam , int yDiam)

2 )实心圆角矩形void fillRoundRect(int top , int left , int width , int height , int xDiam , int yDiam)

参数列表 ：圆角矩形的左上角坐标，宽度，高度，X轴上的弧度，Y轴上的弧度

4.画椭圆和圆形

1)空心圆：void drawOval(int top , int left , int width , int height)

2)实心圆:void fillOval(int top , int left , int width , int height)

参数列表 :左上角坐标，宽，高

5.画圆弧

1)空心圆弧：void drawArc(int top , int left , int width , int height , int startAngle , int sweepAngle);

2)实心圆弧： void fillArc(int top , int left , int width , int height , int startAngle , int sweepAngle);

参数列表 ：在左上角坐标为(top , left)宽为width 高为 height的矩形中画圆弧 ，startAngle是与3点钟的角度 ，sweepAngel是与startAngle的角度。

6.画多边形

1)空心多边形：void drawP

2)实心多边形：

import java.awt.Frame;
import java.awt.Panel;
import java.awt.Graphics;
import java.awt.Color;
public class Test04{
    
    public static void main(String[] args){
        
        Frame f = new Frame();
        f.setSize(1000,1000);
        MyPanel mp = new MyPanel();
        f.add(mp);        
        f.show();
    }
}
class MyPanel extends Panel{
    
    public void paint(Graphics g){
        
        g.drawLine(100,50,100,100);
        g.drawString("Hello World !",120,100);
        g.setColor(Color.green);
        g.drawRect(100,100,200,100);
        g.fillRect(350,100,200,100);
        g.drawRoundRect(600,100,200,100,50,50);
        g.fillRoundRect(850,100,200,100,20,100);
        g.drawOval(100,250,100,100);
        g.fillOval(250,250,80,100);
        g.drawArc(350,250,100,100,0,90);
        g.fillArc(450,250,100,100,0,90);
        g.fillArc(550,250,100,100,10,80);

    }
}

二、Graphics类的应用

1、绘制五角星

import java.awt.Frame;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Panel;
import java.math.*;
public class Test02
{
    public static void main(String[] args)
    {
        Frame f = new Frame();
        f.setSize(1000,1000);
        f.setBackground(Color.black);
        MyPanel mp = new MyPanel();
        f.add(mp);
        f.show();
    }
}
class MyPanel extends Panel
{
    public void paint(Graphics g)
    {
        double xA= 2 , yA= 2 , c = 2,j36,j18,j54;
        double xB ,yB ,xC,yC,xD ,yD,xE ,yE,xf,yf,xg,yg;
        j36 = Math.toRadians(36);//转化成角度
        j18 = Math.toRadians(18);
        j54 = Math.toRadians(54);
        xB = xA+c*Math.cos(j36);
        yB = yA-c*Math.sin(j36);
        xC = xA+2*c*Math.cos(j36);
        yC = yA;
        xD = xA+c*Math.sin(j18);
        //System.out.println("xD ="+xD+" c*Math.sin(18)"+c*Math.sin(18) );
        yD = yA+c*Math.cos(j18);
        xE = xC - c*Math.sin(j18);
        yE = yD;
        xf = xD+c/2;
        yf = yD-(c/2)*Math.tan(j36);
        xg = xE - c/(2*Math.sin(j54))*Math.sin(j18);
        yg = yE - c/(2*Math.sin(j54))*Math.cos(j18);
        //int xpoints[] = {(int)(xB*100),(int)(xD*100),(int)(xC*100),(int)(xA*100),(int)(xE*100),(int)(xB*100)};
        //int ypoints[] = {(int)(yB*100),(int)(yD*100),(int)(yC*100),(int)(yA*100),(int)(yE*100),(int)(yB*100)};
        int xpoints[] = {(int)(xB*100),(int)(xD*100),(int)(xE*100),(int)(xB*100)};
        int ypoints[] = {(int)(yB*100),(int)(yD*100),(int)(yE*100),(int)(yB*100)};
        int num = 4 ;
        //System.out.println((int)(xA*100)+"    "+(int)(yA*100)+" , "+(int)(xD*100)+"  "+(int)(yD*100));
        g.setColor(Color.white);
        g.fillPolygon(xpoints,ypoints,num);
        int xpoints1[] = {(int)(xA*100), (int)(xC*100),(int)(xE*100),(int)(xA*100)};
        int ypoints1[] = {(int)(yA*100),(int)(yC*100),(int)(yE*100),(int)(yA*100)};
        g.fillPolygon(xpoints1,ypoints1,num);
        g.setColor(Color.black);
        int xpoints2[] = {(int)(xD*100),(int)(xf*100),(int)(xE*100),(int)(xD*100)};
        int ypoints2[] = {(int)(yD*100),(int)(yf*100),(int)(yE*100),(int)(yD*100)};    
        g.fillPolygon(xpoints2,ypoints2,4);//减去多余的部分
        int xpoint3[] = {(int)(xE*100),(int)(xg*100),(int)(xC*100),(int)(xE*100)};
        int ypoint3[] = {(int)(yE*100),(int)(yg*100),(int)(yC*100),(int)(yE*100)};
        g.fillPolygon(xpoint3,ypoint3,4);//减去多余的部分
                    
    }
}

                   五角星的坐标图                                      运行结果图

2.随机输出星号

 

import java.awt.Frame;
import java.awt.Panel;
import java.awt.Graphics;
public class Test03
{
    public static void main(String[] args)
    {
        Frame f = new Frame();
        f.setSize(500,500);
        MyPanel mp = new MyPanel();
        f.add(mp);
        f.show();
        
    }
}
class MyPanel extends Panel
{
     public void paint(Graphics g)
    {
        for(int i=0 ;i<50;i++)
        {
            int x = (int)(Math.random()*500);//生成0-500的随机数
            int y = (int)(Math.random()*500);
            g.drawString("*",x,y);
        }
    }
}