java 圖像處理兩例：圖像縮放與圓角圖片的制作

package test;

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.geom.RoundRectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class ChangeImage {

public static BufferedImage makeRoundedCorner(BufferedImage image,
        int cornerRadius) {
    int w = image.getWidth();
    int h = image.getHeight();
    BufferedImage output = new BufferedImage(w, h,
            BufferedImage.TYPE_INT_ARGB);

    Graphics2D g2 = output.createGraphics();

    // This is what we want, but it only does hard-clipping, i.e. aliasing
    // g2.setClip(new RoundRectangle2D ...)

    // so instead fake soft-clipping by first drawing the desired clip shape
    // in fully opaque white with antialiasing enabled...
    g2.setComposite(AlphaComposite.Src);
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);
    g2.setColor(Color.WHITE);
    g2.fill(new RoundRectangle2D.Float(0, 0, w, h, cornerRadius,
            cornerRadius));

    // ... then compositing the image on top,
    // using the white shape from above as alpha source
    g2.setComposite(AlphaComposite.SrcAtop);
    g2.drawImage(image, 0, 0, null);

    g2.dispose();

    return output;
}

public static BufferedImage createResizedCopy(Image originalImage, int scaledWidth,
        int scaledHeight, boolean preserveAlpha) {
    int imageType = preserveAlpha ? BufferedImage.TYPE_INT_RGB
            : BufferedImage.TYPE_INT_ARGB;
    BufferedImage scaledBI = new BufferedImage(scaledWidth, scaledHeight,
            imageType);
    Graphics2D g = scaledBI.createGraphics();
    if (preserveAlpha) {
        g.setComposite(AlphaComposite.Src);
    }
    g.drawImage(originalImage, 0, 0, scaledWidth, scaledHeight, null);
    g.dispose();
    return scaledBI;
}

public static void main(String[] args) throws IOException {
    BufferedImage icon = ImageIO.read(new File("/home/june/桌面/mm.jpg"));
    BufferedImage rounded = makeRoundedCorner(icon, 30);
    ImageIO.write(rounded, "png", new File("/home/june/桌面/mm_rounded.png"));

    BufferedImage pic = ImageIO.read(new File("/home/june/桌面/zhang.jpg"));
    BufferedImage resized = createResizedCopy(pic, 250, 250*768/1024, true);
    ImageIO.write(resized, "jpg", new File("/home/june/桌面/zhang_small.jpg"));
}


}</pre>