[mapserver-users] Scaling Image Symbol Offset

[Havard Tveite]

Dear Steve,

Is this another case for allowing the user to explicitly specify
the centre of a symbol (as proposed in RFC 45 -
http://mapserver.org/development/rfc/ms-rfc-45.html)?

Håvard

Steve Lime wrote:
> Hi David: There is no connection between offset and symbol size. The offset is independent and given
> as a constant value in pixels (although it is scaled). Sounds like you need to change it dynamically based
> on your image size and that can't be done as things sit now. Can you fix your image size or is it and I'm
> missing something.
> 
> Steve
> 
>>>> On 7/16/2009 at 3:51 AM, in message
> <9C37154DC7C8074FBC34214363755B7C33087F at ITB-SVR-01.itbeyond.local>, "David
> Martin" <David at itbeyond.com.au> wrote:
>> I am developing a new application and am rendering around a load of
>> graphic symbol layers using a Map file layer such as
>>
>> LAYER
>>
>>     NAME        cape_headland_point
>>
>>     STATUS      ON
>>
>>     GROUP       all
>>
>>     DATA        'ExplorOz/Places/Cape,Headland,Point'
>>
>>     TYPE        POINT
>>
>>     SYMBOLSCALE 1000000
>>
>>     CLASS
>>
>>         STYLE
>>
>>             SYMBOL [POIImage]
>>
>>             MAXSIZE 15
>>
>>             MINSIZE 4
>>
>>             SIZE 8
>>
>>         END
>>
>>     END
>>
>>     METADATA
>>
>>           "wms_title"         "Capes, Headlands & Points"
>>
>>       END
>>
>>     PROJECTION
>>
>>         "+proj=longlat +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +no_defs"
>>
>>     END
>>
>> END
>>
>> As you can see I am sizing the output symbol which is a 20x20px PIXMAP
>> image - this is working great however the position of the image needs to
>> be OFFSET up by half the size of the image (to make the actual point be
>> the center of the image) - I have tried using OFFSET however when the
>> image size changes (based on SYMBOLSCALE)the offsets are wrong. Is there
>> a way to OFFSET image symbols based on the SYMBOLSCALE and MAX/MIN
>> SIZES?
>>
>> Regards
>>
>> David
> 
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> 

-- 
Håvard Tveite
Department of Mathematical Sciences and Technology, UMB
Drøbakveien 31, POBox 5003, N-1432 Ås, NORWAY
Phone: +47 64965483 Fax: +47 64965401 http://www.umb.no/imt/