パッケージのImageReadParamを使用して、画像のフラグメントを読み取って表示できます。これは、画像全体を読み取らずにImageIO
を使用して単一のフラグメントを読み取る方法を示す基本的な例です。ImageReadParam
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.imageio.ImageReadParam;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;
import javax.swing.*;
public class TestImageChunks {
private static void createAndShowUI() {
try {
URL url = new URL(
"http://duke.kenai.com/wave/.Midsize/Wave.png.png");
Image chunk = readFragment(url.openStream(), new Rectangle(150,
150, 300, 250));
JOptionPane.showMessageDialog(null, new ImageIcon(chunk), "Duke",
JOptionPane.INFORMATION_MESSAGE);
} catch (IOException e) {
JOptionPane.showMessageDialog(null, e.getMessage(), "Failure",
JOptionPane.ERROR_MESSAGE);
e.printStackTrace();
}
}
public static BufferedImage readFragment(InputStream stream, Rectangle rect)
throws IOException {
ImageInputStream imageStream = ImageIO.createImageInputStream(stream);
ImageReader reader = ImageIO.getImageReaders(imageStream).next();
ImageReadParam param = reader.getDefaultReadParam();
param.setSourceRegion(rect);
reader.setInput(imageStream, true, true);
BufferedImage image = reader.read(0, param);
reader.dispose();
imageStream.close();
return image;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowUI();
}
});
}
}
結果は次のようになります。