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Java绘图-第19章

1.Java绘图类

1.1Graphics类

Graphics类是用于绘制图形的抽象类，它是java.awt包中的一部分。Graphics类提供了各种方法，可以在图形上绘制各种形状、文本和图像。这些方法包括画线、画矩形、画椭圆、画弧、绘制图像等。

1.2Graphics2D类

Graphics2D类是java.awt包中的一个子类，它扩展了Graphics类，提供了更多的绘图功能和灵活性。Graphics2D类支持更高级的绘图操作，包括渐变、缩放、旋转等。它是Java 2D API 的一部分，用于在二维平面上执行各种图形操作。

以下是一些Graphics2D类中常用的方法：

1. 设置颜色：

   void setColor(Color c)
   

2. 设置渐变：

   void setPaint(GradientPaint paint)
   

3. 设置线条宽度：

   void setStroke(Stroke s)
   

4. 绘制直线：

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

5. 绘制形状：

   void draw(Shape s)
   

6. 填充形状：

   void fill(Shape s)
   

7. 设置字体：

   void setFont(Font font)
   

8. 绘制字符串：

   void drawString(String str, int x, int y)
   

9. 绘制图像：

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

10. 旋转：

    void rotate(double theta, double x, double y)
    

11. 缩放：

    void scale(double sx, double sy)
    

12. 平移：

    void translate(double tx, double ty)
    

使用Graphics2D类的示例可以嵌入在paintComponent方法中，例如：

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;import javax.swing.JPanel;public class MyPanel extends JPanel {@Overrideprotected void paintComponent(Graphics g) {super.paintComponent(g);Graphics2D g2d = (Graphics2D) g;// 设置抗锯齿g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);// 绘制直线g2d.drawLine(10, 10, 100, 100);// 设置颜色g2d.setColor(Color.BLUE);// 绘制矩形g2d.drawRect(120, 10, 80, 50);// 设置渐变GradientPaint gradient = new GradientPaint(200, 10, Color.RED, 300, 60, Color.YELLOW);g2d.setPaint(gradient);// 填充椭圆g2d.fillOval(220, 10, 100, 60);}
}

在这个示例中，我们创建了一个Graphics2D对象，启用了抗锯齿，并使用了一些Graphics2D的方法来绘制直线、矩形和填充椭圆。这只是Graphics2D类的一小部分功能，你可以根据需要探索更多的方法来满足你的绘图需求。

例题1-7

1.绘制奥运五环

2.绘制实心与空心的集合图形

3.在窗体中显示图片

4.通过滑动条改变图片大小

5.翻转图片

6.让图片围绕左上角点旋转

7.让照片变成向左倾斜的平行四边形形状

8.绘制文字钟表

1-7例题代码汇总

package nineteen;import javax.swing.*;
import java.awt.*;
import java.awt.Graphics;public class DrawCircle extends JFrame {private final int OVAL_WIDTH=80;private final int OVAL_HEIGHT=80;public DrawCircle(){initialize();}private void initialize(){setSize(300,200);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setContentPane(new DrawPanel());setTitle("绘图实例1");}class DrawPanel extends JPanel{public void paint(Graphics g){g.drawOval(10,10,OVAL_WIDTH,OVAL_HEIGHT);g.drawOval(80,10,OVAL_WIDTH,OVAL_HEIGHT);g.drawOval(150,10,OVAL_WIDTH,OVAL_HEIGHT);g.drawOval(50,70,OVAL_WIDTH,OVAL_HEIGHT);g.drawOval(120,70,OVAL_WIDTH,OVAL_HEIGHT);}}public static void main(String[] args){new DrawCircle().setVisible(true);}
}

package nineteen;import javax.swing.*;
import java.awt.*;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;public class DrawFrame extends JFrame {public DrawFrame(){setTitle("绘图实例2");setSize(300,200);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new CanvasPanel());}class CanvasPanel extends JPanel{public void paint(Graphics g){Graphics2D g2 = (Graphics2D) g;Shape[] shapes = new Shape[4];shapes[0] = new Ellipse2D.Double(5,5,100,100);shapes[1] = new Rectangle2D.Double(110,5,100,100);shapes[2] = new Rectangle2D.Double(15,15,80,80);shapes[3] = new Ellipse2D.Double(120,15,80,80);for(Shape shape:shapes){Rectangle2D bounds = shape.getBounds2D();if(bounds.getWidth()==80) {g2.fill(shape);g.setColor(Color.BLUE);}else g2.draw(shape);}}}public static void main(String[] args){new DrawFrame().setVisible(true);}
}

package nineteen;import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.IOException;public class DrawImage extends JFrame{Image img;
public DrawImage(){try{img= ImageIO.read(new File("src/20220909223037.png"));}catch(IOException e){e.printStackTrace();}setSize(440,300);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new CanvasPanel());setTitle("繪製圖片");
}
class CanvasPanel extends JPanel{public void paint(Graphics g){Graphics2D g2 = (Graphics2D) g;g2.drawImage(img,0,0,this);}
}
public static void main(String[] args){new DrawImage().setVisible(true);
}
}

package nineteen;import java.awt.*;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.event.*;public class ImageZoom extends JFrame {Image img;private int imgWidth,imgHeight;private JSlider jSlider;public ImageZoom() {try {img=ImageIO.read(new File("src/20220909223037.png"));//读取图片文件}catch (IOException e) {e.printStackTrace();}CanvasPanel canvas =new CanvasPanel();jSlider = new JSlider();jSlider.setMaximum(1000);jSlider.setValue(100);jSlider.setMaximum(1);jSlider.addChangeListener(new ChangeListener(){public void stateChanged(ChangeEvent e) {canvas.repaint();}});JPanel center =new JPanel();center.setLayout(new BorderLayout());center.add(jSlider,BorderLayout.SOUTH);center.add(canvas,BorderLayout.CENTER);setContentPane(center);setBounds(100,100,800,600);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setTitle("绘制图片");}class CanvasPanel extends JPanel{public void paint(Graphics g) {int newW=0,newH =0;imgWidth =img.getWidth(this);imgHeight =img.getHeight(this);float value =jSlider.getValue();newW =(int)(imgWidth*value/10);newH =(int)(imgHeight*value/10);g.drawImage(img, 0, 0, newW, newH, this );}	}public static void main(String[] args) {new ImageZoom().setVisible(true);}}

package nineteen;import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;import javax.imageio.*;
public class PartImage extends JFrame {private Image img;private int dx1,dy1,dx2,dy2;private int sx1,sy1,sx2,sy2;private int width=1920,height =1080;private JButton vBtn=null;private JButton hBtn=null;private CanvasPanel canvasPanel =null;public PartImage() {try {img=ImageIO.read(new File("src/20220909223037.png"));//读取图片文件}catch (IOException e) {e.printStackTrace();}dx2 =sx2 =width;dy2 =sy2= height;vBtn =new JButton("垂直");hBtn =new JButton("水平");JPanel bottom=new JPanel();bottom.add(hBtn);bottom.add(vBtn);Container c=getContentPane();c.add(bottom,BorderLayout.SOUTH);canvasPanel =new CanvasPanel();c.add(canvasPanel,BorderLayout.CENTER);addListener();setBounds(400,400,600,560);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setTitle("图片翻转");}private void addListener() {vBtn.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {sy1=Math.abs(sy1-height);sy2=Math.abs(sy2-height);canvasPanel.repaint();}});hBtn.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {sx1=Math.abs(sx1-width);sx2=Math.abs(sx2-width);canvasPanel.repaint();}});}class CanvasPanel extends JPanel{public void paint(Graphics g) {g.drawImage(img, dx1, dy1, dx2, dy2, sx1, sy1, sx2, sy2, this);//绘制指定大小}}public static void main(String[] args) {new PartImage().setVisible(true);}}

package nineteen;import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.IOException;public class RotateImage extends JFrame {private Image img;public RotateImage(){try{img = ImageIO.read(new File("src/20220909223037.png"));}catch (IOException e){e.printStackTrace();}setBounds(100,100,400,350);add(new  CanvasPanel());setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setTitle("图片旋转");}class CanvasPanel extends JPanel{public void paint(Graphics g){Graphics2D g2 = (Graphics2D) g;g2.rotate(Math.toRadians(5));g2.drawImage(img,70,10,300,200,this);g2.rotate(Math.toRadians(5));g2.drawImage(img,70,10,300,200,this);g2.rotate(Math.toRadians(5));g2.drawImage(img,70,10,300,200,this);}}public static void main(String[] args){new RotateImage().setVisible(true);}
}

package nineteen;import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.IOException;public class TiltImage extends JFrame {private Image img;public TiltImage(){try{img = ImageIO.read(new File("src/20220909223037.png"));}catch(IOException e){e.printStackTrace();}setBounds(100,100,400,300);add(new CanvasPanel());setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setTitle("图片倾斜");}class CanvasPanel extends JPanel{public void paint(Graphics g){Graphics2D g2 = (Graphics2D)g;g2.shear(0.3,0);g2.drawImage(img,0,0,300,200,this);}
}
public static void main(String[] args){new TiltImage().setVisible(true);
}
}

package nineteen;import javax.swing.*;
import java.awt.*;
import java.awt.geom.Rectangle2D;
import java.util.Date;public class DrawString extends JFrame {public DrawString(){setSize(230,140);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);add(new CanvasPanel());setTitle("绘图文本");}class CanvasPanel extends JPanel{public void paint(Graphics g){Graphics2D g2=(Graphics2D) g;Rectangle2D rect = new Rectangle2D.Double(10,10,200,80);Font font= new Font("宋体",Font.BOLD,16);Date date = new Date();g2.setColor(Color.CYAN);g2.fill(rect);g2.setColor(Color.BLUE);g2.setFont(font);g2.drawString(String.format("%tr",date),50,60);}}public static void main(String[] args){new DrawString().setVisible(true);}
}