[mapserver-dev] Letterspacing is different for polyline labels

[thomas bonfort]

Any objection in pushing this into 6.2 ? From all my tests, there were
no more or no less inter-character collisions when reducing the
letterspacing, and it has the added advantage of a consistent output
between ANGLE AUTO and ANGLE FOLLOW labels (follow labels fall back to
"auto" mode when the line has only two vertices).

regards,
thomas

On Tue, Jul 24, 2012 at 10:46 PM, Lime, Steve D (DNR)
<Steve.Lime at state.mn.us> wrote:
> +1 on the change (it'll bust a few regression tests...)
>
> Steve
>
> -----Original Message-----
> From: mapserver-dev-bounces at lists.osgeo.org [mailto:mapserver-dev-bounces at lists.osgeo.org] On Behalf Of Oliver Tonnhofer
> Sent: Tuesday, July 24, 2012 9:34 AM
> To: mapserver-dev at lists.osgeo.org
> Subject: [mapserver-dev] Letterspacing is different for polyline labels
>
> Hi,
>
> while comparing the rendering of Mapnik and Mapserver I found out that the letter spacing of line labels is much larger with  Mapserver.
>
> After diving into the source code, I found out that labels on a straight line are rendered differently than on curved lines. As mentioned in #4026, the inter-character spacing is defined in the font itself, but that spacing is multiplied by 1.25 when a label is rendered on a polyline.
> See: https://github.com/mapserver/mapserver/blob/master/mapprimitive.c#L1818
>
>
> Here you can see how "Alter Wall" and "Neuer Wall" are rendered with different spacing. "Alter Wall" is on a straight line, while "Neuer Wall" is on a curved line.
> https://dl.dropbox.com/u/2633201/issues/mapserver/letterspacing-125.png
>
> Changing the letterspacing to 1.0 in mapprimitive.c makes the rendering more similar:
> https://dl.dropbox.com/u/2633201/issues/mapserver/letterspacing-100.png
>
> The output is now also quite similar to the output of Mapnik (after adapting the fontsize).
>
> I've created a ticket for that issue: https://github.com/mapserver/mapserver/issues/4404
>
> Regards,
> Oliver
>
> --
> Oliver Tonnhofer    | Omniscale GmbH & Co KG    | http://omniscale.de
> http://mapproxy.org | https://github.com/olt | @oltonn
>
>
>
>
>
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