Anyone how to resize an image using imagereader and imagereadparam?

Question

I want to use imagereaderparam to process the image.
MY code is as follow:
ImageReader reader = _editor.getImageReader();
     try
     if (reader != null)
               int w = reader.getWidth(0);
               int h = reader.getHeight(0);
               ImageReadParam param = reader.getDefaultReadParam();
               //param.setDestination(reader.read(0));
               Dimension d = new Dimension(my_width, my_height);
               param.setSourceRenderSize(d);
               BufferedImage bi = reader.read(0, param);
     } catch (Exception e)
          e.printStackTrace();
This code just not work , and get an exception
java.lang.UnsupportedOperationException: Can't set source render size!
anyone know how to do that ?
coz i dont want to use getScaledImage...

Answer 1

Hi,
Are you just trying to produce a BufferedImage at a smaller size? May I ask why you don't want to use getScaledInstance? I agree with you not to use it. It is slow. Just wondering what your reasons are. If all you need is to take one image and make it a different size, try this:
BufferedImage src = ...
int scale = 0.5f;
int w = (int)(src.getWidth(null) * scale);
int h = (int)(src.getHeight(null) * scale);
// could use TYPE_INT_RGB if there's no alpha in your image
BufferedImage dest = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
Graphics g = dest.getGraphics();
g.drawImage(src, 0, 0, w, h, null);
d.dispose();How does that work for you? It should be pretty quick.
Shannon Hickey (Swing Team)