[Fwd: [UMN_MAPSERVER-USERS] different symbol for elements of
the same layer via cgi?]
woodbri at SWOODBRIDGE.COM
Thu May 31 16:55:46 EDT 2007
Schuyler Erle wrote:
> * On 31-May-2007 at 10:25AM PDT, Stephen Woodbridge said:
>> Steve L,
>> Here is a good use case for being able to bind a column to a symbol
>> image. I'm not sure if you had thought of this or if this would be
>> possible. But how about something like:
>> SYMBOLIMAGE "/path/to/symbols/[symbol].png"
>> SYMBOLIMAGE [symbol]
> I have a concrete use case for this, if I understand the problem
> correctly. I have a table of POIs and I want to display different
> icons based on the POI attribute. Unless I'm sorely mistaken, I
> haven't been able to figure how to do it with MS 4.10 without
> resorting to MapScript.
Right! Steve has been doing some work make it easier to bind stuff to
attribute columns as in both of these examples. If you have a fixed
number of symbols then you can use CLASS EXPRESSIONs to select the
symbol, but in the example above EVERY point had a unique symbol image.
I think this case needs to be handled a little differently than the
SYMBOL case. With SYMBOLs there is some preprocessing to cache the
symbols. In the all or most are unique class, you probably just want the
path or URL to the symbol and have it copied into the image.
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