Rotate an image in java

Question

I am looking to rotate an image. I have a JInternalFrame which contains a JLabel. The label contains the image. After the image has been rotated, I need to resize the internal frame. The code I have currently rotates the image, but there is black around the edges of the image and it is off centered. Any suggestions on how to fix this?

public void rotateIcon(int angle)
{
        int w = theLabel.getIcon().getIconWidth();
        int h = theLabel.getIcon().getIconHeight();
        int type = BufferedImage.TYPE_INT_RGB;  // other options, see api

        BufferedImage DaImage = new BufferedImage(h, w, type);
        Graphics2D g2 = DaImage.createGraphics();

        double x = (h - w)/2.0;
        double y = (w - h)/2.0;
        AffineTransform at = AffineTransform.getTranslateInstance(x, y);

        at.rotate(Math.toRadians(angle), w/2.0, h/2.0);
        g2.drawImage(new ImageIcon(getData()).getImage(), at, theLabel);
        g2.dispose();

        theLabel.setIcon(new ImageIcon(DaImage));
        this.setSize(DaImage.getWidth(),DaImage.getHeight()); //resize the frame
}

In general, rotating an image changes the width and height (relative to X and Y axes). I'd guess this is contributing to it being "off centered." I've had to solve this by calculating the new size and accounting for it. As for the black edges, this is a pretty common case where the the rotating function isn't working with an alpha channel. Maybe this will help for the positioning: http://stackoverflow.com/questions/2056338/calculating-the-center-of-rotation-after-translation — Jere, Nov 11 '10 at 16:24

score 19 · Accepted Answer · edited Mar 18 '16 at 21:46

You need to be using trigonometry to determine the correct width/height, using transparency to prevent the black area, and I think the Transform is wrong, which is making it off center.

Try this:

public static BufferedImage rotate(BufferedImage image, double angle) {
    double sin = Math.abs(Math.sin(angle)), cos = Math.abs(Math.cos(angle));
    int w = image.getWidth(), h = image.getHeight();
    int neww = (int)Math.floor(w*cos+h*sin), newh = (int) Math.floor(h * cos + w * sin);
    GraphicsConfiguration gc = getDefaultConfiguration();
    BufferedImage result = gc.createCompatibleImage(neww, newh, Transparency.TRANSLUCENT);
    Graphics2D g = result.createGraphics();
    g.translate((neww - w) / 2, (newh - h) / 2);
    g.rotate(angle, w / 2, h / 2);
    g.drawRenderedImage(image, null);
    g.dispose();
    return result;
}

private static GraphicsConfiguration getDefaultConfiguration() {
    GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
    GraphicsDevice gd = ge.getDefaultScreenDevice();
    return gd.getDefaultConfiguration();
}

from http://flyingdogz.wordpress.com/2008/02/11/image-rotate-in-java-2-easier-to-use/

This is really cool. I am having one issue with it though. My image only needs to rotate 90 degrees. at a time. If I pass in 90 for angle, it will actually rotate more than 90 degrees — user489041, Nov 11 '10 at 17:45
This is using radians, so just use Math.toRadians(degree) first. — Reverend Gonzo, Nov 11 '10 at 18:54

score 4 · Answer 2 · answered Nov 11 '10 at 16:20

4

You could try using a Rotated Icon.

answered Nov 11 '10 at 16:20

camickr

321,443
19
166
288

Thanks, I am going to have to look into this. – user489041 Nov 11 '10 at 17:50

score 1 · Answer 3 · answered Jun 25 '19 at 10:58

Based on a previous example, but actually working with recent JDKs and in headless mode:

public static BufferedImage rotate(BufferedImage image, double angle) {
    double sin = Math.abs(Math.sin(angle)), cos = Math.abs(Math.cos(angle));
    int w = image.getWidth(), h = image.getHeight();
    int neww = (int)Math.floor(w*cos+h*sin), newh = (int) Math.floor(h * cos + w * sin);
    BufferedImage result = deepCopy(image, false);
    Graphics2D g = result.createGraphics();
    g.translate((neww - w) / 2, (newh - h) / 2);
    g.rotate(angle, w / 2, h / 2);
    g.drawRenderedImage(image, null);
    g.dispose();
    return result;
}

public static BufferedImage deepCopy(BufferedImage bi, boolean copyPixels) {
    ColorModel cm = bi.getColorModel();
    boolean isAlphaPremultiplied = cm.isAlphaPremultiplied();
    WritableRaster raster = bi.getRaster().createCompatibleWritableRaster();
    if (copyPixels) {
        bi.copyData(raster);
    }
    return new BufferedImage(cm, raster, isAlphaPremultiplied, null);
}

score 0 · Answer 4 · answered Nov 11 '10 at 16:26

0

Does it help if you change:

BufferedImage DaImage = new BufferedImage(height, width, type);

to:

BufferedImage DaImage = new BufferedImage(**width, height**, type);?

answered Nov 11 '10 at 16:26

bjoernz

3,852
18
30

Yea, I switched those back and forth, still no success. – user489041 Nov 11 '10 at 17:49

Rotate an image in java

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