Java绘图-第19章

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 {

    @Override
    protected 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);
    }
}

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