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/pnewimageformatIO.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：
1 int alpha = (cARGB >> 24)& 0xff; //透明度通道
2 int red = (cARGB >> 16) &0xff;
3 int green = (cARGB >> 8) &0xff;
4 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());
frame.getContentPane().add(new PlasmaDemo(), BorderLayout.CENTER);
frame.setPreferredSize(new Dimension(400 + 25,450));
frame.pack();
frame.setVisible(true);
}
}
