显示PGM格式图片的面板实现

PGM是一种简易的图片格式，仅仅通过描述各点的灰度值表示。为了简单，这里采用更简单的图片格式，即只存储各点灰度值。比如一个5*5的图片如下所示。

0 0 10 10 0 0
0 0 10 10 0 0
0 0 10 10 0 0
0 0 10 10 0 0
0 0 10 10 0 0

为了显示这样的图片，这里实现一种简易的面板，从文本中读取灰度值，然后显示。

具体代码如下所示。

import java.awt.Dimension;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.Image;import java.awt.image.BufferedImage;import java.awt.image.WritableRaster;import java.io.File;import java.io.FileNotFoundException;import java.util.Scanner;import javax.swing.JPanel;public class PgmPanel extends JPanel {public static final int WIDTH=512;public static final int HEIGHT=512;private int[][] pixels;public PgmPanel(String pgmFile) {super();pixels = new int[WIDTH][HEIGHT];try {Scanner scan=new Scanner(new File(pgmFile));int row=0;while(scan.hasNext()){String line=scan.nextLine();if(line==null)continue;int k=0;for(String p:line.split(" "))pixels[row][k++]=Integer.parseInt(p);++row;}scan.close();} catch (FileNotFoundException e) {e.printStackTrace();}}@Overridepublic Dimension getPreferredSize() {return new Dimension(WIDTH, HEIGHT);}@Overridepublic void paint(Graphics g) {super.paint(g);Graphics2D g2d=(Graphics2D) g;BufferedImage img=new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_BYTE_GRAY);WritableRaster raster=img.getRaster();for(int k=0;k<pixels.length;++k)for(int j=0;j<pixels[k].length;++j)raster.setPixel(j, k, new int[]{pixels[k][j]});g2d.drawImage(img, 0, 0, WIDTH, HEIGHT, null);}}

在构造函数中读取灰度值，在paint函数中绘图。这里使用BuffededImage类构建了一个图片，使用TYPE_BYTE_GRAY模式。然后用WritableRaster类对图片中的每个点设置灰度值。

面板实现后，加入一个JFrame中即可显示。

以一个图片为例，其文本如下所示。

0 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 100 120 140 160 180 200 220 240 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

面板显示效果如下所示。