Rotating a BufferedImage

Question

I have been rotating a BufferedImage using the following code where m_Image is the BufferedImage:
AffineTransform trans = new AffineTransform();
AffineTransformOp op = null;
int imgWidth = m_Image.getWidth();
int imgHeight = m_Image.getHeight();
trans.rotate( Math.toRadians(degrees), imgWidth / 2, imgHeight / 2 );
AffineTransformOp op = new AffineTransformOp(trans, new RenderingHints(
RenderingHints.KEY_COLOR_RENDERING,
RenderingHints.VALUE_COLOR_RENDER_QUALITY));
m_Image = op.filter(m_Image, null);
The degrees variable is only ever 90, 180 or 270.
The problem occurs when degrees is 90 or 270 and the image is rectangular. After rotation the final image is square in shape and has black edging on one side.
Am I doing something wrong or am I missing something? Any suggestions welcomed.

Answer 1

When you pass in a null for the filter call, it creates a destination BufferedImage for you. I assume that the BufferedImage it createsw has the same size as the source image (there's no way for it to know what size you want it if e.g. you rotate by 30 degrees).
When you rotate by 90 or 270, the resulting image has the height and width swapped. You should construct a destination image with the height and width swapped from the source image and use that in the filter call.
I used the following code:
int w = image.getWidth();
int h = image.getHeight();
if( numQuadrants % 2 != 0 ) {
int temp = w;
w = h;
h = temp;
BufferedImage retval = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
op.filter(image, retval);
return retval;