Java绘图,图像处理

Java绘图类

1.Graphics类
提供了绘图常用的方法，利用这些方法可以实现直线，矩形，多边形等文本，图片的绘制其操作主要包括颜色，字体，画笔，文本，图像等

2.Graphics2D类
使用Graphics2D类可以实现更强的图像绘制功能

3.将Graphics强制转换成Graphics2D类：

public static void paint(Graphics g){Graphics2D g2 = (Graphics2D)g;
}

绘制图形

Graphics 类常用图形绘制方法

方法	说明
draw(int x,int y,int height,int startAngle,int arcAngle)	弧形
drawLine(int x1,int y1,int x2,int y2)	直线
drawOval(int x,int y,int width,int height)	椭圆
drawPolygon(int[] xPoints,int[] yPoints,int nPoints)	多边形
drawPolyline(int[] xPoints,int[] yPoints,int nPoints)	多边线
drawRect(int x,int y,int width,int height)	矩形
drawRoundRect(int x,int y,int width,int height,int arcWidth,int arcAngle)	圆角矩形
fillArc(int x,int y,int width,int height,int startAngle,int arcAngle)	实心弧形
fillOval(int x,int y,int width,int height)	实心椭圆
fillPolygon(int[] xPoints,int[] yPoints,int nPoints)	实心多边形
fillRect(int x,int y,int width,int height)	实心矩形
fillRoundRect(int x,int y,int width,int height,int arcWidth,int arcHeight)	实心圆角矩形

当我们要绘制图形时，我们必须要进行创建并初始化图形类对象。这些图形必须时Shape接口的实现类，然后使用Graphics2D类的draw方法进行绘制，或者fill方法进行填充。

语法：

draw(Shape form)
fill(Shape form)

常用图形类：
主函数：

 public static void main(String[] args) {new G_1().setVisible(true);}

Arc2D类：弧

Graphics2D g2d =(Graphics2D)g;Shape[] shapes = new Shape[3];shapes[0] = new Arc2D.Double(50,50,185,160,10,90,Arc2D.OPEN);//坐标位置(50，50)，宽85，高60，起始角是5度，终止角是90度shapes[1] = new Arc2D.Double(150,150,185,160,10,90,Arc2D.CHORD);shapes[2] = new Arc2D.Double(200,300,185,160,10,90,Arc2D.PIE);for (Shape shape:shapes){//遍历图形数组g2d.draw(shape);//绘制图形}
//Arc2D.OPEN、Arc2D.CHORD、Arc2D.PIE分别表示圆弧是开弧、弓弧和饼弧。

CubicCurve2D类：立方曲线

 class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d =(Graphics2D)g;Shape[] shapes = new Shape[1];shapes[0] =new CubicCurve2D.Double(100,100,50,75,15,15,260,300);//参数分别表示坐标起点，控制点1，控制点2，终点的坐标for (Shape shape:shapes){//遍历图形数组g2d.draw(shape);//绘制图形}}}

Ellipse2D类：椭圆

class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d =(Graphics2D)g;Shape[] shapes = new Shape[1];shapes[0] = new Ellipse2D.Double(150,150,200,100);//参数表示起点，宽，高for (Shape shape:shapes){//遍历图形数组g2d.draw(shape);//绘制图形}}}

class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d =(Graphics2D)g;Shape[] shapes = new Shape[1];shapes[0] = new Ellipse2D.Double(150,150,200,100);//参数表示起点，宽，高for (Shape shape:shapes){//遍历图形数组g2d.draw(shape);//绘制图形}}}

Line2D类：线

class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d =(Graphics2D)g;Shape[] shapes = new Shape[1];shapes[0] = new Line2D.Double(10,150,250,150);//参数表示起点和终点for (Shape shape:shapes){//遍历图形数组g2d.draw(shape);//绘制图形}}}

Point2D类：点
QuadCurve2D类：二次曲线

class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d =(Graphics2D)g;Shape[] shapes = new Shape[1];shapes[0] = new QuadCurve2D.Double(100,100,10,150,250,300);//参数表示起点,控制点，终点for (Shape shape:shapes){//遍历图形数组g2d.draw(shape);//绘制图形}}}

Rectangle2D类：矩形
RoundRectangle2D类：圆角矩形
例子：

import javax.swing.*;
import java.awt.*;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;public class G_1 extends JFrame {public G_1(){setTitle("绘图实例");setSize(500,500);//设置窗体大小setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置窗体的关闭模式add(new CanvasPanel());//设置窗体画板为绘图画板对象}class CanvasPanel extends JPanel{   //绘图画板public void paint(Graphics g){Graphics2D g2d = (Graphics2D)g;Shape[] shapes = new Shape[4];//声明图形数组shapes[0] = new Ellipse2D.Double(5,5,100,100);//创建圆形对象shapes[1] = new Rectangle2D.Double(110,5,160,40);//矩形shapes[2] = new Ellipse2D.Double(120,15,80,80);shapes[3] = new Rectangle2D.Double(35,15,80,80);for (Shape shape:shapes){//遍历图形数组Rectangle2D bounds = shape.getBounds2D();if (bounds.getWidth()==80){g2d.fill(shape);//填充}else {g2d.draw(shape);//绘制图形}}}}public static void main(String[] args) {new G_1().setVisible(true);}
}

程序展示：

绘图颜色和画笔属性

1.设置颜色
语法：

Color col = new Color(int r,ing g,int b);//参数表示三原色
Color col = new Color(int rgb);//参数表示颜色值，是三原色的总和

在绘图类中使用setColor方法快速设置颜色

g.setColor(Color.color)//注意是有.的

例子：

import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;public class G_2 extends JFrame {public G_2(){setTitle("Graphics2D绘制测试");setSize(500,500);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new drawplace());}class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d =(Graphics2D)g;g2d.setColor(Color.green);Shape[] shapes = new Shape[1];shapes[0] = new Ellipse2D.Double(150,150,200,200);for (Shape shape:shapes){//遍历图形数组g2d.fill(shape);g2d.draw(shape);//绘制图形}}}public static void main(String[] args) {new G_2().setVisible(true);}
}

程序展示：

设置画笔
语法：

Stroke st = new BasicStroke(4);
g2d.setStroke(st);

例子：

import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;public class G_2 extends JFrame {public G_2(){setTitle("Graphics2D绘制测试");setSize(500,500);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new drawplace());}class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d =(Graphics2D)g;g2d.setColor(Color.green);Stroke st = new BasicStroke(15);g2d.setStroke(st);Shape[] shapes = new Shape[1];shapes[0] = new Ellipse2D.Double(150,150,200,200);for (Shape shape:shapes){//遍历图形数组//g2d.fill(shape);g2d.draw(shape);//绘制图形}}}public static void main(String[] args) {new G_2().setVisible(true);}
}

程序展示：

常用构造方法：

BasicStroke()
BasicStroke(float width)
BasicStroke(float width,int cap,int join)
BasicStroke(float width,int cap,int join,float miterlimit)
BasicStroke(float width,int cap,int join,float miterlimit,float[] dash,float dash_phase)

BasicStroke类构造方法的参数说明

参数	说明
width	画笔宽度默认为1px
cap	线端点装饰
join	应用在路径线段交汇处的装饰
miterlimit	斜接处的剪裁限制，参数必须大于等于1.0f
dash	表示虚线模式的数组
dash_phase	开始虚线模式的偏移量

cap参数的三个常量：

CAP_BUTT：末端圆滑
CAP_ROUND：末端平整
CAP_SQUARE：末端设置以线段宽度为边长的方形

join参数的三个常量：

JOIN_BEVEL：平角
JOIN_MITER：尖角
JOIN_ROUND：圆角

绘制文本

1.设置字体
可以设置名称，样式，字体大小
语法：

Font f = new Font("方正舒体",Font.BOLD,25);
g2d.setFont(f);

Font类的常量：

PLAIN：普通
BOLD：加粗
ITALIC：斜体
ITALIC|BOLD：斜体加粗

例子：

import javax.swing.*;
import java.awt.*;public class G_3 extends JFrame {public G_3(){setTitle("font_test");setSize(400,400);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new drawplace());}class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d = (Graphics2D)g;Font f = new Font("方正舒体",Font.BOLD,25);g2d.setFont(f);g2d.drawString("文字：方正舒体",100,100);}}public static void main(String[] args) {new G_3().setVisible(true);}
}

程序展示：

例子：

import javax.swing.*;
import java.awt.*;
import java.util.Date;public class G_3 extends JFrame {public G_3(){setTitle("font_test");setSize(400,400);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new drawplace());}class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d = (Graphics2D)g;Date time = new Date();Font f = new Font("方正舒体",Font.BOLD,25);g2d.setColor(Color.RED);g2d.setFont(f);g2d.drawString("现在是：",50,100);g2d.drawString(String.format("%tr",time),100,200);}}public static void main(String[] args) {new G_3().setVisible(true);}
}

程序展示：

显示图片

使用drawImage方法将图片显示到绘图中
语法：

drawImage(Image img,int x,int y,ImageObserver observer)

参数表示要显示的图片对象，坐标，要通知的图像观察者
例子:

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.IOException;public class show_photos extends JFrame {Image img;public show_photos(){try{img = ImageIO.read(new File("D:\\work\\累.png"));}catch(IOException e){e.printStackTrace();}setTitle("show_photos");setSize(916,525);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new drawplace());}class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d = (Graphics2D)g;g2d.drawImage(img,0,0,this);}}public static void main(String[] args) {new show_photos().setVisible(true);}
}

程序展示：

图像处理

1.放大和缩小
依然使用drawImage方法语法：

drawImage(Image img,int x,int y,int width,int height,ImageObserver observer)

例子：

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.IOException;public class show_photos extends JFrame {Image img;public show_photos(){try{img = ImageIO.read(new File("D:\\work\\累.png"));}catch(IOException e){e.printStackTrace();}setTitle("show_photos");setSize(916,525);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new drawplace());}class drawplace extends JPanel{public void paint(Graphics g){Graphics2D g2d = (Graphics2D)g;g2d.drawImage(img,0,0,300,200,this);}}public static void main(String[] args) {new show_photos().setVisible(true);}
}

程序展示：

例子（用划片改变大小）：

import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.*;
import java.io.File;
import java.io.IOException;public class show_p_change extends JFrame {Image img;int imgwidth,imgheight;private JSlider js;public show_p_change(){try{img = ImageIO.read(new File("D:\\work\\累.png"));}catch(IOException e){e.printStackTrace();}showplace sp = new showplace();js = new JSlider();js.setMaximum(1500);js.setValue(50);js.setMinimum(10);js.addChangeListener(new ChangeListener() {@Overridepublic void stateChanged(ChangeEvent e) {sp.repaint();}});JPanel center = new JPanel();center.setLayout(new BorderLayout());center.add(js,BorderLayout.SOUTH);center.add(sp,BorderLayout.CENTER);setContentPane(center);setTitle("change_p_show");setBounds(100,100,800,600);//设置窗体大小和位置setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);}class showplace extends JPanel{public void paint(Graphics g){Graphics2D g2d = (Graphics2D)g;int n_w = 0,n_h = 0;imgwidth = img.getWidth(this);imgheight = img.getHeight(this);float value = js.getValue();n_w = (int)(imgwidth*value/100);n_h = (int)(imgheight*value/100);g2d.drawImage(img,0,0,n_w,n_h,this);}}public static void main(String[] args) {new show_p_change().setVisible(true);}
}

程序展示：

图像翻转
语法：

drawImage(image img,int x1,int y1,int x2,int y2,int x3,int y3,int x4,int y4,ImageObserver observer)

参数说明：

参数	说明
img	要绘制的对象
x1	目标矩阵第一个坐标的x位置
y1	目标矩阵第一个坐标的y位置
x2	目标矩阵第二个坐标的x位置
y2	目标矩阵第二个坐标的y位置
x3	源矩阵第一个坐标的x位置
y3	源矩阵第一个坐标的y位置
x4	源矩阵第二个坐标的x位置
y4	源矩阵第二个坐标的y位置
observer	要通知的图像观察者

例子：

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;public class G_flip extends JFrame {Image img;int dx1,dy1,dx2,dy2;int sx1,sx2,sy1,sy2;int imgw= 800,imgh=500;//照片的宽高JButton vbtn = null;//垂直翻转JButton hbtn = null;//水平翻转Cpanel canvas = null;public G_flip(){try{img = ImageIO.read(new File("D:\\work\\累.png"));}catch(IOException e){e.printStackTrace();}dx2 = sx2  =imgw;dy2 = sy2 = imgh;vbtn = new JButton("垂直翻转");hbtn = new JButton("水平翻转");JPanel bottom = new JPanel();bottom.add(vbtn);bottom.add(hbtn);Container c = getContentPane();c.add(bottom,BorderLayout.SOUTH);canvas = new Cpanel();c.add(canvas,BorderLayout.CENTER);addL();setBounds(100,100,800,700);setTitle("图像翻转");setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);}void addL(){vbtn.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {sy1 = Math.abs(sy1-imgh);   //纵坐标交换sy2 = Math.abs(sy2-imgh);canvas.repaint();}});hbtn.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {sx1 = Math.abs(sx1-imgw);   //横坐标交换sx2 = Math.abs(sx2-imgw);canvas.repaint();}});}class Cpanel extends JPanel{public void paint(Graphics g){Graphics2D g2d = (Graphics2D)g;g2d.drawImage(img,dx1,dy1,dx2,dy2,sx1,sy1,sx2,sy2,this);}}public static void main(String[] args) {new G_flip().setVisible(true);}
}

程序展示：

图像旋转
使用Graphics2D中的rotate方法根据弧度旋转图像语法：

rotate(double 旋转弧度)

我们可以使用Math类中的toRadians方法把旋转角度转化为弧度
例子：

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.IOException;public class G_route extends JFrame {Image img;public G_route(){try{img = ImageIO.read(new File("D:\\work\\累.png"));}catch(IOException e){e.printStackTrace();}setBounds(100,100,800,800);setTitle("图像旋转");setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new Cp());}class Cp extends JPanel{public void paint(Graphics g){Graphics2D g2d = (Graphics2D)g;g2d.rotate(Math.toRadians(10));g2d.drawImage(img,100,100,300,300,this);g2d.rotate(Math.toRadians(60));g2d.drawImage(img,300,-300,300,300,this);}}public static void main(String[] args) {new G_route().setVisible(true);}
}

程序展示：