GVT problem with GaussianBlur

[Edison Too <ed...@yahoo.com.sg>]

Hi,

I understand that this question is related to GVT (part of Batik) and not
Batik/SVG directly. If someone can help me with GVT privately, I'd
thankfully refrain from sending GVT questions to the list. Sorry if this
causes inconvenience to you as a list user.

I'm trying to draw a gaussian blurred rectangle on to the Graphics passed in
via the paintComponent(g) call of JComponent. To do this, I call the
paint(g2d,rc) method of a CanvasGraphicsNode I've already set up. This has
only one node set-up as below.

    GraphicsNode aNode = GVTSupport.createShapeNode(new
Rectangle(50,150,100,60),Color.red,null,null);
    GraphicsNodeRenderContext rc = GVTSupport.getRenderContext();
    Filter aFilter =
GVTSupport.getGNRFactory().createGraphicsNodeRable(aNode,rc);
    aFilter = new GaussianBlurRable8Bit(aFilter,2.0f,2.0F);
    aNode.setFilter(aFilter);
    rootGN.add(aNode);

GVTSupport is a convenience class with which I construct the node.

The problem is that though the Rectangle is drawn, the gaussian blur didn't
work the way I expected. I can see that the blurring was carried out,but the
pixels were still either red (the fill color) or white (the background
color). Instead of a blurred edge with color changing from red to white, I
see a distinct edge. I can tell that blurring has occurred because, the
resultant rectangle has rounded corners and is larger than the original
rectangle.

I suspect it is some kind of color space issue, but I couldn't figure out
what I did wrong. If anyone could see it, please let me know. Thanks in
advance. :)

Cheers,
Edison


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RE: GVT problem with GaussianBlur

[Edison Too <ed...@yahoo.com.sg>]

Hi, Thomas

Thanks for the help, I just figured this out too. The problem went away when
I use a BufferedImage. I guess, I'll just have to create an off-screen
buffer. :)

Best regards,
Edison

> -----Original Message-----
> From: Thomas E Deweese [mailto:thomas.deweese@kodak.com]
> ET> I suspect it is some kind of color space issue, but I couldn't
> ET> figure out what I did wrong. If anyone could see it, please let me
> ET> know. Thanks in advance. :)
>
>     Well, I don't know that this is a huge help, but I suspect your
> 'color space issue' is in fact a problem with the alpha channel.
> There are a number destination image types that don't handle alpha
> correctly in the JDK, we generally work around these by drawing to an
> image type we know works.
>
>     So I would suggest trying to have your Graphics node drawn to a
> BufferedImage.TYPE_INT_ARGB, then draw that to the given graphics.
>
> I hope this helps!


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GVT problem with GaussianBlur

[Thomas E Deweese <th...@kodak.com>]

>>>>> "ET" == Edison Too <ed...@yahoo.com.sg> writes:

ET> The problem is that though the Rectangle is drawn, the gaussian
ET> blur didn't work the way I expected. I can see that the blurring
ET> was carried out,but the pixels were still either red (the fill
ET> color) or white (the background color). Instead of a blurred edge
ET> with color changing from red to white, I see a distinct edge. I
ET> can tell that blurring has occurred because, the resultant
ET> rectangle has rounded corners and is larger than the original
ET> rectangle.

ET> I suspect it is some kind of color space issue, but I couldn't
ET> figure out what I did wrong. If anyone could see it, please let me
ET> know. Thanks in advance. :)

    Well, I don't know that this is a huge help, but I suspect your
'color space issue' is in fact a problem with the alpha channel.
There are a number destination image types that don't handle alpha
correctly in the JDK, we generally work around these by drawing to an
image type we know works.  

    So I would suggest trying to have your Graphics node drawn to a
BufferedImage.TYPE_INT_ARGB, then draw that to the given graphics.

I hope this helps!

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