寫了很多篇關于圖像處理的文章，沒有一篇介紹Java 2D的圖像處理API，文章討論和提及的
API都是基于JDK6的，首先來看Java中如何組織一個圖像對象BufferedImage的，如圖：
一個BufferedImage的像素數據儲存在Raster中，ColorModel里面儲存顏色空間，類型等
信息，當前Java只支持一下三種圖像格式- JPG,PNG,GIF,如何向讓Java支持其它格式，首
先要 完成Java中的圖像讀寫接口，然后打成jar，加上啟動參數- Xbootclasspath/p
newimageformatIO.jar即可。
Java中如何讀寫一個圖像文件，使用ImageIO對象即可。讀圖像文件的代碼如下：
- File file = new File("D:\\test\\blue_flower.jpg");
- BufferedImage image = ImageIO.read(file);
寫圖像文件的代碼如下：
- File outputfile = new File("saved.png");
- ImageIO.write(bufferedImage, "png",outputfile);
從BufferedImage對象中讀取像素數據的代碼如下：
- int type= image.getType();
- if ( type ==BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
- return (int [])image.getRaster().getDataElements(x, y, width, height, pixels );
- else
- return image.getRGB( x, y, width, height, pixels, 0, width );
首先獲取圖像類型，如果不是32位的INT型數據，直接讀寫RGB值即可，否則需要從Raster
對象中讀取。
往BufferedImage對象中寫入像素數據同樣遵守上面的規則。代碼如下：
- int type= image.getType();
- if ( type ==BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
- image.getRaster().setDataElements(x, y, width, height, pixels );
- else
- image.setRGB(x, y, width, height, pixels, 0, width );
讀取圖像可能因為圖像文件比較大，需要一定時間的等待才可以，Java Advance Image
Processor API提供了MediaTracker對象來跟蹤圖像的加載，同步其它操作，使用方法如下：
- MediaTracker tracker = new MediaTracker(this); //初始化對象
- tracker.addImage(image_01, 1); // 加入要跟蹤的BufferedImage對象image_001
- tracker.waitForID(1, 10000) // 等待10秒，讓iamge_01圖像加載
從一個32位int型數據cARGB中讀取圖像RGB顏色值的代碼如下：
- int alpha = (cARGB >> 24)& 0xff; //透明度通道
- int red = (cARGB >> 16) &0xff;
- int green = (cARGB >> 8) &0xff;
- int blue = cARGB & 0xff;
將RGB顏色值寫入成一個INT型數據cRGB的代碼如下：
- cRGB = (alpha << 24) | (red<< 16) | (green << 8) | blue;
創建一個BufferedImage對象的代碼如下：
- BufferedImage image = newBufferedImage(256, 256, BufferedImage.TYPE_INT_ARGB);
一個完整的源代碼Demo如下：
- package com.gloomyfish.swing;
-
- import java.awt.BorderLayout;
- import java.awt.Dimension;
- import java.awt.Graphics;
- import java.awt.Graphics2D;
- import java.awt.RenderingHints;
- import java.awt.image.BufferedImage;
- import java.io.File;
- import java.io.IOException;
-
- import javax.imageio.ImageIO;
- import javax.swing.JComponent;
- import javax.swing.JFrame;
-
- public class PlasmaDemo extends JComponent {
-
- /**
- *
- */
- private static final long serialVersionUID = -2236160343614397287L;
- private BufferedImage image = null;
- private int size = 256;
-
- public PlasmaDemo() {
- super();
- this.setOpaque(false);
- }
-
- protected void paintComponent(Graphics g) {
- Graphics2D g2 = (Graphics2D)g;
- g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
- g2.drawImage(getImage(), 5, 5, image.getWidth(), image.getHeight(), null);
- }
-
- private BufferedImage getImage() {
- if(image == null) {
- image = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
- int[] rgbData = new int[size*size];
- generateNoiseImage(rgbData);
- setRGB(image, 0, 0, size, size, rgbData);
- File outFile = new File("plasma.jpg");
- try {
- ImageIO.write(image, "jpg", outFile);
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- return image;
- }
-
- public void generateNoiseImage(int[] rgbData) {
- int index = 0;
- int a = 255;
- int r = 0;
- int g = 0;
- int b = 0;
-
- for(int row=0; row<size; row++) {
- for(int col=0; col<size; col++) {
- // set random color value for each pixel
- r = (int)(128.0 + (128.0 * Math.sin((row + col) / 8.0)));
- g = (int)(128.0 + (128.0 * Math.sin((row + col) / 8.0)));
- b = (int)(128.0 + (128.0 * Math.sin((row + col) / 8.0)));
-
- rgbData[index] = ((clamp(a) & 0xff) << 24) |
- ((clamp(r) & 0xff) << 16) |
- ((clamp(g) & 0xff) << 8) |
- ((clamp(b) & 0xff));
- index++;
- }
- }
-
- }
-
- private int clamp(int rgb) {
- if(rgb > 255)
- return 255;
- if(rgb < 0)
- return 0;
- return rgb;
- }
-
- public void setRGB( BufferedImage image, int x, int y, int width, int height, int[] pixels ) {
- int type = image.getType();
- if ( type == BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
- image.getRaster().setDataElements( x, y, width, height, pixels );
- else
- image.setRGB( x, y, width, height, pixels, 0, width );
- }
-
- public static void main(String[] args) {
- JFrame frame = new JFrame("Noise Art Panel");
- frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
- frame.getContentPane().setLayout(new BorderLayout());
-
- // Display the window.
- frame.getContentPane().add(new PlasmaDemo(), BorderLayout.CENTER);
- frame.setPreferredSize(new Dimension(400 + 25,450));
- frame.pack();
- frame.setVisible(true);
- }
- }