[Mapserver-users] Autonumbering of labels?

[Stephen Woodbridge]

Doug,

Part of the problem in doing this has to do with the label cache and how 
it treats label collisions and how you want to deal with these. For 
example, if I have 2 points in my current map and the are so close 
together that one lays on top of the other, the label cache would not 
render the second label and therefore you would only have one label on 
the map. This is compounded by the fact the you have to assign the 
numbers to the labels BEFORE you put them in the cache and you only know 
if they have to be removed AFTER the numbers are assigned which will 
leave gaps in the number sequences, and you can't cost effectively 
re-label the cache when one gets bumped out by a collision.

On the other hand, if you don't care about collisions and are using the 
equivalent of FORCE all labels to be drawn then most of the above issues 
away.

This is a pretty simple application of mapscript, in fact most virtual 
data sources in mapscript do a database query to get the point that 
belong in the current map extents and then just cycle through them and 
draw and label them on top of the current map image over writing 
whatever is under them.

-Steve W.

Doug wrote:

> Steve Lime wrote:
> 
>> Nope, that functionality doesn't exist. For clarification, you mean only
>> the features actually labeled? That may be tough because labels are
>> assigned before
>> being queued for rendering and this would need to be far more dynamic.
>>
>> If you could expand on your idea that would help...
>>
>> Steve
>>
>>
>>>>> Brad Cantwell <bcantwel at us.ibm.com> 6/3/2004 1:56:37 PM >>>
>>
>>
>>
>> Is there a way to do sequential numbering for labels?  We would like
>> to
>> have the labels for features autonumbered (i.e. 1 though N).  Is there
>> a
>> way to do this through the .map file?    We are trying to avoid
>> MapScript
>> if possible.
> 
> 
> I work with Brad, and here's what we need to do.  We have a layer of 
> specific locations that we need to show on the drawn map.  However, we 
> need the locations to be numbered somehow such that for any particular 
> map, the numbers always start at 1.  i.e. dynamically giving a temporary 
> "ID" to each location based on what is currently visible.
> 
> One person suggested creating a dynamic database view with an 
> autonumbered column, but we haven't succeeded with that approach yet. We 
> were also wondering if there are other options.
> 
> Doug
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