[mapserver-users] Fractional line widths?

[Dane Springmeyer]

Hi All,

So, as of r7923 MapServer can now render some super thin lines using  
the subpixel rendering of AGG. The change allows you to enter values  
for the WIDTH parameter as doubles/fractions which can give the result  
I've been looking for.

I think is really cool, and if anyone is interested in the different  
results you can check out the image comparisons I've posted on this  
ticket:

http://trac.osgeo.org/mapserver/ticket/2745#comment:6

Thanks dmorrissette, sdlime, and tbonfort for making this happen!

Dane



On Sep 4, 2008, at 7:10 PM, Dane Springmeyer wrote:

> Thomas,
>
> Thanks for the tip, but I think I don't quite understand the right  
> syntax.
>
> First of all, I'm running the mac binary from kyngchaos, version 5.2.0
>
> I've tried to add two style blocks like:
>
>   LAYER
>     NAME         world_opacity
>     DATA         world_borders.shp
>     STATUS      ON
>     TYPE          POLYGON
>     CLASS
>       NAME       "World"
>       STYLE
>         COLOR                 242 239 249
>         OUTLINECOLOR    -1 -1 -1
>       END
>       STYLE
>         COLOR                 -1 -1 -1
>         OUTLINECOLOR   127 127 127
>         OPACITY 50
>         WIDTH 1
>       END
>     END # class
>   END # layer
>
> to create this full mapfile: http://mapnik-utils.googlecode.com/svn/trunk/tutorials/hello_world/mapserver_comparison/mapfile_config/world.map
>
> But that does not produce a result more akin to WIDTH 0.5, from what  
> I can tell. It simply lightens the color of the outline, and in this  
> case make it 'seem' even thicker. It is as if the opacity is not  
> working as a true alpha opacity.
>
> Here is the example output with OPACITY 50:
>
> http://mapnik-utils.googlecode.com/svn/trunk/tutorials/hello_world/mapserver_comparison/mapfile_config/map/hello_world_with_mapserver_mapfile_opacity.png
>
> Is this the expected behavior or have I made an error in my mapfile  
> syntax (highly likely). Perhaps I am not correctly turning off the  
> outline for the first style?
>
> The issue may also be with my OUTPUTFORMAT, which is not using the  
> RGBA:
>
>   OUTPUTFORMAT
>    NAME 'AGG'
>    DRIVER AGG/PNG
>    IMAGEMODE RGB
>    MIMETYPE "image/png"
>   END
>
> I also tried with:
>
>   OUTPUTFORMAT
>    NAME 'AGGA'
>    DRIVER AGG/PNG
>    IMAGEMODE RGBA
>    MIMETYPE "image/png"
>   END
>
> but I get an error when I add the 'AGGA' (based on reading http://mapserver.gis.umn.edu/docs/howto/agg-rendering-specifics) 
> :
>
> msPostMapParseOutputFormatSetup(): General error message. Unable to  
> select IMAGETYPE `AGG'.
>
>
> Any thoughts?
>
> Thanks,
>
> Dane
>
>
>
> On Aug 31, 2008, at 2:50 PM, thomas bonfort wrote:
>
>> hi.
>> yes, you need two style blocks inside your class
>> cheers,
>> thomas
>>
>> On Sun, Aug 31, 2008 at 9:43 PM, Dane Springmeyer  
>> <blake at hailmail.net> wrote:
>>> Hi Thomas,
>>>
>>> Thanks for the followup.
>>>
>>> The OPACITY keyword seems to apply to both the polyon fill (COLOR)  
>>> and the
>>> outline (OUTLINECOLOR).
>>>
>>> What is the trick to apply it to only the outline? I tried  
>>> OUTLINEOPACITY,
>>> which of course does not exist.
>>>
>>> Do I need to pull out a style class for just the outline?
>>>
>>> Here is the mapfile I am working from:
>>>
>>> http://mapnik-utils.googlecode.com/svn/trunk/tutorials/hello_world/mapserver_comparison/mapfile_config/world.map
>>>
>>> Thanks,
>>>
>>> Dane
>>>
>>>
>>> On Aug 30, 2008, at 12:22 AM, thomas bonfort wrote:
>>>
>>>> Sorry for not hopping into the thread earlier, blame holidays :)
>>>>
>>>> For the time being, you can achieve similar output with mapserver  
>>>> 5.2,
>>>> by using the OPACITY keyword at the style level
>>>>
>>>> STYLE
>>>> COLOR r g b
>>>> OPACITY 50  # essentially the same as WIDTH 0.5
>>>> WIDTH 1
>>>> END
>>>>
>>>> cheers,
>>>> thomas
>>>>
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