Hi Stephan,
"Stephan Zuiderwijk" <[EMAIL PROTECTED]> wrote on
12/05/2005 02:04:16 AM:
> thank you for your fast reply. I've been playing around with your
> sugestions. It works fine. Because of the large amount of items (app.
5500)
> I cached the circle elements when my JSVGCanvas is first opened.
If the update is slow (and I suspect it might be as our CSS engine has
some O(N^2) behavior when modifying all the children of a group), and you
are not afraid of a small 'hack' you might consider using the stroke to
adjust the 'size' of the circles:
<g stroke-width="2" fill="red" stroke="red">
<circle r="0.0000001" cx="..." .../>
<circle r="0.0000001" ..../>
</g>
To update the 'radius' of the circles you now only need to update
the 'stroke-width' on the surrounding 'g' element. The CSS engine will
quickly cascade this to all of the children in one step. The other
advantage is that I think this will only update the shape painter instead
of essentially rebuilding the circle from scratch.
But it is a hack (in the best sense of the word) and will basically
only work for circles.
>
> Kind regards,
>
> Stephan Zuiderwijk
>
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> Sent: Friday, December 02, 2005 11:46 AM
> To: batik-users@xmlgraphics.apache.org
> Subject: Re: Scaling in batik extension
>
> Hi Stephan,
>
> "Stephan Zuiderwijk" <[EMAIL PROTECTED]> wrote on
> 12/01/2005 09:03:49 AM:
>
> > I'm quite new to batik, I've got a question about scaling in batik. In
> > a
> Java
> > application I am showing map of europe in a JSVGCanvas. The cities are
> shown
> > as little red circles. [...] what I want to achieve is the following.
> When a
> > user zooms in at the map, the circles should resize so that they stay
> > at
> the
> > same size for the user's point of view. Can anybody help me out with
> this?
>
> You want to capture 'onzoom' events. You can then query the
> currentScale on
> the root SVG element. You can then use this to update the 'r' attribute
> on
> your circle elements (this is mostly easily done if all the circles are
> the
> child of a 'cities' layer or something, then you can just iterate
through
> all the element children of the group and update the 'r' attribute).
>
> All of this can be done in either script or Java.
>
>
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