[mapserver-dev] Letterspacing is different for polyline labels

thomas bonfort thomas.bonfort at gmail.com
Mon Jul 30 10:41:41 PDT 2012


Just checked, it dates from the initial patch that was provided to the
project in 2006.

--
thomas

On Mon, Jul 30, 2012 at 7:38 PM, Daniel Morissette
<dmorissette at mapgears.com> wrote:
> Do we know when the 1.25 factor was introduced and by who? My only concern
> would be to not undo something that may have been done for a good reason,
> otherwise I have no objection.
>
> Daniel
>
>
> On 12-07-30 12:50 PM, thomas bonfort wrote:
>>
>> 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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>>>
>>>
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>>
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>
>
> --
> Daniel Morissette
> http://www.mapgears.com/
> Provider of Professional MapServer Support since 2000
>
>
>
>
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