Mark Claassen wrote:
Thanks for the reply.
As it turns out, we are using a static document already. We went ahead
and actually set the state to be static, but we still get the memory
problem if we zoom enough. (It seems that we are now able to zoom a bit
more, although this may just be a coincidence.) From your description,
we thought it was futile to override the createImageRenderer method as
this point.
It seems to me that if the tiles are rendered lazily, we could zoom
indefinitely and use a relatively constant amount of memory. Also, we
have never noticed the document being painted as we scroll. If the
tiles truley were rendered lazily, I would except to see this.
Maybe we are just doing something wrong. We weren't quite sure how to
get the zoom we wanted using the API directly, so we resize the canvas
to zoom. To zoom 2X, we:
Dimension d = canvas.getSize();
d.width = d.width * 2;
d.height = d. height * 2;
canvas.setPreferredSize(d)
canvas.revalidate();
Is there a better way?
Yes change the rendering transform, take a look at Zoom(In|Out)?Action
in JSVGCanvas.java you are actually doubling the size of the 'visible'
canvas so it creates an offscreen that size.
-----Original Message-----
From: Thomas DeWeese [mailto:[EMAIL PROTECTED]
Sent: Friday, August 08, 2003 12:10 PM
To: Batik Users
Subject: Re: Lazy rendering and zoom
Mark Claassen wrote:
I noticed there is a setProgressivePaint(boolean) method in
JGVTComponent. This seems to display items on the canvas
as they are
rendered, and not just display the whole document at once.
What I was wondering was if there is an option that goes a step
further, and would restrict rendering to just viewable
area. This is
a common thing in Swing, where, for instance, the rows of a
table that
are not currently visible in a JScrollPane are never rendered.
The default zooming behaviour in Batik seems to render a portion of
the document while not changing the canvas size. We would like to
change the canvas size, so that the we can pan to see any
part of the
document we need simply by moving the scrollbars.
Unfortunately, this
causes OutOfMemory errors when the zoom factor gets large.
I know we can increase the JVM heap size, but this can only
go so far.
What I was hoping for was something in the JSVGCanvas that
would draw
just a portion of the document on the canvas, and then when
a scroll
occurred, it would noticed that this area had not been rendered and
draw that. One could even go so far as to anticipate the
loading of
sections and use SortReferences to hold now longer visible sections.
Is there anything like this, or any plans to include something like
this?
Hi Mark,
This is already done for Static Documents. The Static
Renderer keeps a tiled view of the image and when translates
happen it tries to populate the new view from the stored
tiles. This is generally not done for dynamic documents as
maintaining the tile store is expensive for many small
changes (the system would widens rendering requests to tile
boundries) also there were a few bugs in what I will call odd
cases (the size/location of the root SVG changing). However
depending on your context this still might be a win for your
case. It is pretty easy to change this by overiding the
following method in batik.swing.svg.JSVGComponent:
protected ImageRenderer createImageRenderer() {
if (isDynamicDocument) {
return rendererFactory.createDynamicImageRenderer();
} else {
return rendererFactory.createStaticImageRenderer();
}
}
So it always returns a static ImageRenderer.
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