Proposed RFC on COLORRAMP Support (Bug 13 05)

[Bill Binko]

Steve,

Before I comment on this, just a quick question: what do you think the 
legend entry for that class would look like?

Bill

On Tue, 27 Sep 2005, Steve Lime wrote:

> The runtime substitution does not work everywhere- that's another RFC. Adding
> support for the breaks specifically is doable with this RFC though.
> 
> How do COLORRAMPS and STYLES interact? Steve's example uses old-style code
> for styling. For example, let's say I want to draw a circle with graduated colors and
> also a drop shadow. Typicall I'd do this with 2 styles: 1 for the shadow (offset a bit)
> and the second for the main circle. How do you determine which take advantage
> of the color ramp.
> 
> Working off that, what about defiining ramps at the layer level and then referencing
> the ramps by name wherever a COLOR is passed. That way label colors as well as
> symbol colors could take advantage of ramps. We'd need a way to indicate that a
> color is actually a reference to a color ramp, and then a function to return a color.
> We definitely don't want to have to keep adding new ramp keywords...
> 
> A mapfile snippet might look like:
> 
> LAYER
>   COLORRAMP
>     NAME 'ramp1'
>     ...
>   END
>   COLORRAMP
>     NAME 'ramp2'
>     ...
>   END
> 
>   CLASS
>     STYLE COLOR 181 181 181 OFFSET 1 1 END
>     STYLE COLOR 'ramp1' END    
>     LABEL COLOR 'ramp2' END
>   END  
> END
> 
> Steve
> 
> >>> Bill Binko <bill at BINKO.NET> 09/27/05 3:30 PM >>>
> Stephen, I thought your example would be a good test case to show how you 
> would get what you wanted using the ColorRamp as defined in the RFC.  
> I'm sure it's not 100% what you'd like, but it's fairly close.  
> 
> It does make an assumption that the %% substitution works everywhere, and 
> I'll make sure to add that to the RFC.  It also produces a legend that is 
> a bit different from yours, in that it puts the demographic name on the 
> first class, and then just the high/low values in the graded color bar 
> (see http://mapserver.gis.umn.edu/bugs/attachment.cgi?id=324&action=view )
> 
> Please use this as a starting point, and explain what won't work.  There 
> may very well be some additional work on the legends that is needed, but I 
> think the general need you're expressing is addressed.
> 
> Bill
> 
>   LAYER
>     NAME "zcta_thematic"
>     CONNECTIONTYPE postgis
>     CONNECTION "host=linus port=5432 dbname=census user=pgsql"
>     DATA "the_geom from (SELECT c.gid, c.the_geom, c.water, a.%demographic% as demog from %table% a, 
>           sf3geo_zcta5 b, zcta c where c.state='%state%' and c.name=b.zcta5 and 
>           a.stusab=b.stusab and a.logrecno=b.logrecno and b.stusab='%state%' and 
>           b.sumlev='871'  ) as foo using srid=4326 using unique gid"
>     TYPE POLYGON
>     STATUS ON
>     PROJECTION
>       #"proj=latlong"
>       "init=epsg:4326"
>     END
>     CLASSITEM "water"
>     CLASS
>       NAME "Water"
>       EXPRESSION "t"
>       OUTLINECOLOR 102 102 204
>       COLOR 102 102 204
>     END
>     CLASS
>       NAME "%demog%"
>       EXPRESSION ([demog] > %break0% && [demog] <= %break1%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 102 102 102
> 	MAXCOLOR 0 204 0
> 	MINVALUE %break0%
> 	MAXVALUE %break1%
> 	RANGEITEM 'demog'
>       END
>     END
>     CLASS
>       NAME " "
>       EXPRESSION ([demog] > %break1% && [demog] <= %break2%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 0 204 0
>         MAXCOLOR 51 255 51
>         MINVALUE %break1%
>         MAXVALUE %break2%
>         RANGEITEM 'demog'
>       END
>     END
>     CLASS
>       NAME " "
>       EXPRESSION ([demog] > %break2% && [demog] <= %break3%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 0 204 0
> 	MAXCOLOR 102 255 102
>         MINVALUE %break2%
>         MAXVALUE %break3%
>         RANGEITEM 'demog'
>       END
>     END      
>     CLASS
>       NAME " "
>       EXPRESSION ([demog] > %break3% && [demog] <= %break4%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 102 255 102
> 	MAXCOLOR 153 255 153
>         MINVALUE %break3%
>         MAXVALUE %break4%
>         RANGEITEM 'demog'
>       END
>     END
>     CLASS
>       NAME " "
>       EXPRESSION ([demog] > %break4% && [demog] <= %break5%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 153 255 153
> 	MAXCOLOR 204 255 204
>         MINVALUE %break4%
>         MAXVALUE %break5%
>         RANGEITEM 'demog'
>       END
>     END
>     CLASS
>       NAME " "
>       EXPRESSION ([demog] > %break5% && [demog] <= %break6%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 204 255 204
>         MAXCOLOR 255 294 294
>         MINVALUE %break5%
>         MAXVALUE %break6%
>         RANGEITEM 'demog'
>       END
>     END
>     CLASS
>       NAME " "
>       EXPRESSION ([demog] > %break6% && [demog] <= %break7%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 255 294 294
> 	MAXCOLOR 255 153 153
>         MINVALUE %break6%
>         MAXVALUE %break7%
>         RANGEITEM 'demog'
>       END
>     END
>     CLASS
>       NAME " "
>       EXPRESSION ([demog] > %break7% && [demog] <= %break8%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 255 153 153
>         MAXCOLOR 255 102 102
>         MINVALUE %break7%
>         MAXVALUE %break8%
>         RANGEITEM 'demog'
>       END
>     END
>     CLASS
>       NAME " "
>       EXPRESSION ([demog] > %break8% && [demog] <= %break9%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 255 102 102 
>         MAXCOLOR 255 51 51
>         MINVALUE %break8%
>         MAXVALUE %break9%
>         RANGEITEM 'demog'
>       END
>     END
>     CLASS
>       NAME " "
>       EXPRESSION ([demog] > %break9% && [demog] <= %break10%)
>       OUTLINECOLOR 0 0 0
>       COLORRANGE
>         MINCOLOR 255 51 51
>         MAXCOLOR 255 0 0
>         MINVALUE %break9%
>         MAXVALUE %break10%
>         RANGEITEM 'demog'
>       END
>     END
>   END
> 
>