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From: "Peter Duniho" <peter.duniho@THRWHITE.remove-dii-this>
Subject: Re: Anti-aliasing in imag
Message-ID: <op.ufuticmp8jd0ej@petes-computer.local>
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Date: Wed, 27 Apr 2011 15:48:01 GMT
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  To: comp.lang.java.gui,comp.l
On Wed, 13 Aug 2008 17:55:10 -0700, Kenneth P. Turvey  
<kt-usenet@squeakydolphin.com> wrote:

> I've got a simple problem that I'm sure someone in this group can help me
> with.  Let me say what I'm currently doing first.
>
> I have an image that has some transparent portions and I want to cut a
> circle out of the image.

Do you want to remove a circular area from inside the image?  Or do you  
want to use only a ciruclar area from inside the image as your new image?

That is, the transformed image, will it be the original image with a hole  
in it?  Or will it be the original image with everything outside the  
circular area excluded?

This description:

> So first I trim it down to a square subimage
> and then I go through it pixel by pixel and set the alpha channel to
> clear for those pixels outside a circle with the sub-image's diameter.

Makes me think you're taking a circular subset of the image, but other  
parts of your message seem to contradict that.  I'm a bit confused.

If I have understood the goal correctly, then it seems to me that the  
easiest way to transform your original image is to draw it into a new  
image, clipping to the circular shape you want.

For example, here's some code that works when just drawing into the  
Graphics2D passed to the paintComponent() method:

     // Where x, y, width, and height describe your circular area and image  
is a reference
     // to the image you want to clip

     Area areaOval = new Area(new Arc2D.Double(x, y, width, height, 0, 360,  
Arc2D.PIE));
     Shape shapeClipSave = gfx2.getClip();

     gfx2.setClip(areaOval);
     gfx2.drawImage(image, 0, 0, null);
     gfx2.setClip(shapeClipSave);

You should be able to use basically the same thing drawing into a  
Graphics2D instance you get from a new BufferedImage instance.  Just make  
sure you've enabled anti-aliased rendering, and when the image is drawn  
clipped into the new BufferedImage, the edges should wind up anti-aliased.

Pete

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