Java -- AWT 画图，图像处理

1. AWT画图 Graphics类提供绘制简单图形的方法

更新图片时用到 repaint , update , 程序不应该主动调用paint和update，这两个方法都应该是由AWT系统负责调用，用户重写paint 即可。

示例：

public class Main {

	private final String RECT_SHAPE = "rect";

	private final String OVAL_SHAPE = "oval";

	private Frame f = new Frame();

	private Button rect = new Button("Rect");

	private Button oval = new Button("Oval");

	private String shape = "";

	private MyCanvas drawArea = new MyCanvas();

	void init()

	{

		Panel p = new Panel();

		p.add(rect);

		p.add(oval);

		rect.addActionListener(new ActionListener() {

			@Override

			public void actionPerformed(ActionEvent e) {

				// TODO Auto-generated method stub

				shape = RECT_SHAPE;

				drawArea.repaint();  //重画， 会调用paint方法。。。

			}

		});

		oval.addActionListener(new ActionListener() {

			@Override

			public void actionPerformed(ActionEvent e) {

				// TODO Auto-generated method stub

				shape = OVAL_SHAPE;

				drawArea.repaint();

			}

		});

		f.addWindowListener(new WindowAdapter() {

			public void windowClosing(WindowEvent e)

			{

				System.exit(0);

			}

		});

		drawArea.setPreferredSize(new Dimension(250, 180));

		f.add(drawArea);

		f.add(p, BorderLayout.SOUTH);

		f.pack();

		f.setVisible(true);

	}

	public static void main(String[] args) {

		new Main().init();

	}

	class MyCanvas extends Canvas  // 画布

	{

		public void paint(Graphics g)  //重写paint方法

		{

			Random rand = new Random();

			if(shape.equals(RECT_SHAPE))

			{

				g.setColor(new Color(220, 100, 80));

				g.drawRect(rand.nextInt(200), rand.nextInt(120), 40, 60);

			}

			if(shape.equals(OVAL_SHAPE))

			{

				g.setColor(new Color(80, 100, 200));

				g.fillOval(rand.nextInt(200), rand.nextInt(120), 50, 40);

			}

		}

	}

}

2. 使用image类 BufferedImage 类处理位图

画板：

import java.awt.Canvas;

import java.awt.Color;

import java.awt.Dimension;

import java.awt.Frame;

import java.awt.Graphics;

import java.awt.MenuItem;

import java.awt.PopupMenu;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.event.MouseAdapter;

import java.awt.event.MouseEvent;

import java.awt.event.MouseMotionAdapter;

import java.awt.event.MouseMotionListener;

import java.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

import java.awt.image.BufferedImage;

public class HandDraw {

	/**

	 * @param args

	 */

	//画区大小

	private final int AREA_WIDTH = 500;

	private final int AREA_HEIGHT = 400;

	//鼠标坐标

	private int preX = -1;

	private int preY = -1;

	//右键惨淡

	PopupMenu pop = new PopupMenu();

	MenuItem redItem = new MenuItem("Red");

	MenuItem greenItem = new MenuItem("Green");

	MenuItem blueItem = new MenuItem("Blue");

	//Bufferedimage 对象

	BufferedImage image = new BufferedImage(AREA_WIDTH, AREA_HEIGHT,

			BufferedImage.TYPE_INT_RGB);

	Graphics g = image.getGraphics();

	private Frame f= new Frame("HandDraw");

	private String shape = "";

	private Color foreColor = new Color(255, 0, 0);

	private DrawCanvas drawArea = new DrawCanvas();

	public void init()

	{

		ActionListener menuListener = new ActionListener() {

			@Override

			public void actionPerformed(ActionEvent e) {

				// TODO Auto-generated method stub

				if( e.getActionCommand().equals("Green") )

				{

					foreColor = new Color(0, 255, 0);

					System.out.println("Green");

				}

				else if( e.getActionCommand().equals("Red") )

				{

					foreColor = new Color(255, 0, 0);

					System.out.println("Red");

				}

				else if( e.getActionCommand().equals("Blue") )

				{

					foreColor = new Color(0, 0, 255);

					System.out.println("Blue");

				}

			}

		};

		redItem.addActionListener(menuListener);

		greenItem.addActionListener(menuListener);

		blueItem.addActionListener(menuListener);

		pop.add(redItem);

		pop.add(greenItem);

		pop.add(blueItem);

		drawArea.add(pop);

		drawArea.addMouseListener(new MouseAdapter() {

			public void mouseReleased(MouseEvent e)

			{

				if(e.isPopupTrigger())

				{

					pop.show(drawArea, e.getX(), e.getY());

				}

				preX = -1;

				preY = -1;

			}

		});

		g.fillRect(0, 0, AREA_WIDTH, AREA_HEIGHT);

		drawArea.setPreferredSize(new  Dimension(AREA_WIDTH, AREA_HEIGHT));

		drawArea.addMouseMotionListener(new MouseMotionAdapter() {

			public void mouseDragged(MouseEvent e)

			{

				if( preX > 0 && preY > 0 )

				{

					g.setColor(foreColor);

					g.drawLine(preX, preY, e.getX(), e.getY());

				}

				preX = e.getX();

				preY = e.getY();

				drawArea.repaint();

			}

		});

		f.addWindowListener(new WindowAdapter() {

			public void windowClosing(WindowEvent w)

			{

				System.exit(0);

			}

		});

		f.add(drawArea);

		f.pack();

		f.setVisible(true);

	}

	public static void main(String[] args) {

		// TODO Auto-generated method stub

		new HandDraw().init();

	}

	class DrawCanvas extends Canvas

	{

		public void paint(Graphics g)

		{

			g.drawImage(image, 0, 0, null);

		}

	}

}

3. 使用ImageIO 输入输出位图

ImageIO有静态方法 getReaderFormatNames() 等获取支持的读入写入的图片格式。

public class Main {

	private final int WIDTH = 800;

	private final int HEIGHT = 600;

	BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB );

	Graphics g= image.getGraphics();

	public void zoom() throws IOException

	{

		Image srcImage = ImageIO.read(new File("/home/test/test.png")); //读取图片文件

		g.drawImage(srcImage, 0, 0, WIDTH, HEIGHT, null);  //将原始图片 按固定大小绘制到image中

		ImageIO.write(image, "jpeg", new File("/home/test/testCopy.jpg"));  //写入磁盘

	}

	public static void main(String[] args) throws IOException {

		// TODO Auto-generated method stub

		new Main().zoom();

	}

}

巴特西

Java -- AWT 画图，图像处理

最新文章

热门文章