[mapserver-dev] Labeling Highway Shields Idea

[Stephen Woodbridge]

Thomas,

I created a ticket for this:
    http://trac.osgeo.org/mapserver/ticket/3044

-Steve W

thomas bonfort wrote:
> Steve,
> 
> I like the idea, and think that the style bloc should also be used to 
> render the label background in the simple case (thus deprecating the 
> need for backgroundcolor, backgroundshadowcolor, offsets, etc...). The 
> base object passed to the style rendering funbction would be the 
> shapeboj representing the label's bounding box. This rectanlge can 
> either be rendered normally in the case of a label background, or by 
> using the GEOMTRANSFORM centroid can be used to render shields.
> 
> regards,
> 
> thomas
> 
> On May 21, 2009, at 23:50 , Stephen Woodbridge wrote:
> 
>> Hi all,
>>
>> Currently, unless I'm out of date, if you want to place highway 
>> shields that are symbols as part of a label you have to use an 
>> annotation layer to place the shield as a symbol(s) and the label over 
>> top of that with the number.
>>
>> So this requires, two passes over the data, one to render the highways 
>> and a second pass over the data to place the shields. It also requires 
>> defining and maintaining two layers in place of one.
>>
>> A proposal for an alternate way:
>>
>> One way to do this would be to allow STYLE block(s) to be placed in 
>> the LABEL block and these would use the base label point and be 
>> rendered before the label text and only if the label test is rendered. 
>> I say base label point, because you would still want to be able to use 
>> OFFSET x y to align the label text with the shield symbols. I suppose 
>> you could allow OFFSET x y in the STYLE block to allow separate 
>> positioning of the symbols and to get multiple symbols to align 
>> correctly with one another.
>>
>> The following is an example of how this might look. Sorry, I copied it 
>> from the cpp input file but it should be easy to understand. 
>> _label(font,size,color) is a macro simplify the files. If USE_SHIELDS 
>> is defined it would use the proposal above and render the interstate 
>> shields which is actually three symbols representing the red, white 
>> and blue parts of the shield where each is a vector symbol or you 
>> could have one STYLE block that uses an image symbol for the shield. 
>> If USE_SHIELDS is not defined then you would get a OSM style highway 
>> label in a box, like "[I-290]".
>>
>> Thoughts on this?
>>
>> If people think this would be a good enhancement, I would be happy to 
>> write up a ticket for it.
>>
>> Thanks,
>>  -Steve
>>
>>    CLASS ## Interstate
>>      EXPRESSION "1"
>>      STYLE
>>        WIDTH _motorway_width
>>        OUTLINEWIDTH 1
>>        OUTLINECOLOR _motorway_ol_clr
>>        MINWIDTH _motorway_minwidth
>>        MAXWIDTH _motorway_maxwidth
>>      END
>>      STYLE
>>        WIDTH _motorway_width
>>        COLOR _motorway_clr
>>        MINWIDTH _motorway_minwidth
>>        MAXWIDTH _motorway_maxwidth
>>      END
>> #ifdef USE_SHIELDS
>>      LABEL
>>        MAXSCALEDENOM 3000000
>>        STYLE
>>          SYMBOL "interstate-red"
>>          COLOR _red_clr
>>        END
>>        STYLE
>>          SYMBOL "interstate-blue"
>>          COLOR _blue_clr
>>        END
>>        STYLE
>>          SYMBOL "interstate-white"
>>          COLOR _white_clr
>>        END
>>        _label("arial-bold",10,_white_clr)
>>        PRIORITY 1
>>        MINSIZE 8
>>        MAXSIZE 8
>>        MINDISTANCE 150
>>      END
>> #else
>>      LABEL
>>        MAXSCALEDENOM 3000000
>>        _label("arial-bold",10,_white_clr)
>>        PRIORITY 1
>>        MINSIZE 8
>>        MAXSIZE 8
>>        MINDISTANCE 150
>>        MAXLENGTH 6
>>        BACKGROUNDCOLOR _motorway_lbl_bg_clr
>>        BACKGROUNDSHADOWCOLOR _motorway_lbl_shadow_clr
>>      END
>> #endif
>>    END
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>