[OSM-talk] SVG rendering on wiki

[Tyler]

Sorry Ben,
I thought you were referring to the actual svg
http://wiki.openstreetmap.org/images/8/88/Belgium-trafficsign-a25.svg looking
back at your original message it's clear I wasn't paying attention.

The pngs clearly aren't being rendered transparent, the jaggies for me are
showing up just a little fuzzy from the re-sampling. So, yes, I agree
svg->png rasterization is broken.

-Tyler

On Tue, Jun 30, 2009 at 10:15 AM, Ben Laenen <benlaenen at gmail.com> wrote:

> Tyler wrote:
> > Rendering of SVG is done in browser,
>
> No it isn't (here), it's done on the server by MediaWiki: it takes an svg
> and
> converts it to png (using rsvg or some other program on the server) when
> the
> image appears on a page, and it sends the png to the browser. The image
> used
> on http://wiki.openstreetmap.org/wiki/Image:Belgium-trafficsign-a25.svgfor
> example is this png:
> http://wiki.openstreetmap.org/images/thumb/8/88/Belgium-trafficsign-
> a25.svg/640px-Belgium-trafficsign-a25.svg.png
>
> > the link you sent to me rendered at an
> > appropriate size and very quickly.
>
> Because it sends you the png which is cached by MediaWiki on the server.
> Once
> the conversion from svg to png is done once at a given size, you don't see
> any
> delays, but just take an svg on the wiki and put it in a test page at a
> size
> that wasn't rendered before, and it'll take a minute before you see the
> image
> in your browser. But anyway, the svg conversion time isn't a really big
> problem, as that's only seen once by the person editing a wiki page who
> entered the image into that page.
>
> The main problems are that:
>
> * the png images which were created from svg aren't transparent anymore.
> This
> was done correctly once, so you'll see a mix of images with transparent and
> opaque backgrounds on
>
> http://wiki.openstreetmap.org/wiki/WikiProject_Belgium/Conventions/Traffic_Signs
> although they all have transparent backgrounds actually (the transparent
> ones
> were rendered before the change happened on the server and because they're
> cached they stay transparent, if you take one of the transparent ones and
> put
> it on a page at a different size, they'll be opaque)
>
> * The jagged appearance of some svg images like
> http://wiki.openstreetmap.org/wiki/Image:Belgium-trafficsign-a25.svg (this
> happens in every browser I have, FireFox, Konqueror, Arora) and it's in the
> source code of the page: (from the same page mentioned above:)
>
> <img alt="Image:Belgium-trafficsign-a25.svg"
> src="/images/thumb/8/88/Belgium-
> trafficsign-a25.svg/640px-Belgium-trafficsign-a25.svg.png" width="720"
> height="600" border="0" />
>
> But the rendered png image isn't 720 by 600 pixels as it shows on the page,
> it's actually 640 by 533, and thus you get a stretched image which is
> creating
> the jagged appearance. I have no idea why this is, my own local mediawiki
> installation handles it all just fine.
>
> Ben
>
>
>
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