[Mapserver-users] Autonumbering of labels?

[Steve Lime]

Labeling isn't random so you might be able to figure something out. This
type of an operation usually involves a query to get at attributes of
features you want. So, in MapScript you'd do something like:

- draw a base image for the required extent
- query the points data using that extent
- loop through the results drawing each point on the base image, using a
counter to compute the label values
- produce the output page with the image and the list of point features

So you could have the map with gas station's labeled 1to 10, and then a
list with the names of each station. That's an easy solution...

Steve

>>> Doug <ummmmm at MYREALBOX.COM> 06/08/04 12:22 AM >>>
That is exactly what we want to do.

We have an existing site that uses a commercial product with an 
expensive annual license fee that our project management team would like

to see us replace with OpenSource alternatives.  This site does show a 
textual list of feature attributes whose numbers correspond to labels on

the map.

Are you saying that with or without ordered labelling, there's no way to

order the features predictably?

BTW, thanks for everyone's expert advice.  We're brand new to MapServer 
and still fairly new to GIS in general.

Doug

Steve Lime wrote:

> Actually I think I know how it could be done regardless of the value
of
> force. When you build the labels you could use a special string like
> %rn% to denote a draw time substitution (just like runtime
substitutions
> with the CGI). Then as you plop labels on the map you could keep count
> and each label gets the value of count+1 substituted for %rn%. If a
> label isn't drawn, no biggie cause the counter doesn't go anywhere
> either. 
> 
> I wonder though if there is real value in this. What do the numbers
> really mean? I could see utility in labeling features and then
> referencing them by number elsewhere on a page (e.g. found 5 hotels
> within 10 miles of point x). However, there's no way to tie numbers to
> actual features, not with more work.
> 
> Could someone file a bug/feature request on this one so it doesn't get
> lost? I won't have time until after MUM2 to think about it.
> 
> Steve
> 
> 
>>>>Stephen Woodbridge <woodbri at swoodbridge.com> 06/07/04 4:18 PM >>>
> 
> Steve Lime,
> 
> This should simplify the issues you raised about this feature. 
> Basically, the autonumber feature should just draw all the points in
the
> 
> view using the FORCE option so there are no renumbering issues,
because 
> they are all drawn.
> 
> -Steve W.
> 
> Doug wrote:
> 
> 
>>Stephen Woodbridge wrote:
>>
>>
>>>Doug wrote:
>>>
>>>
>>>>The reason we're trying to stay away from MapScript is the thread 
>>>>safety issues we've been reading about.  That and the fact that we
> 
> do 
> 
>>>>all of our application coding in Java, for which there doesn't
> 
> appear 
> 
>>>>to be any standard, accepted implementation.
>>>>
>>>>So how to people use MapScript anyway if it's not thread safe?  
>>>>Always as separate CGI processes?
>>>
>>>
>>>
>>>Yes, PHP is required to run as a CGI process and likewise for Perl 
>>>(ie: you can not run it as an apache module or mod_perl application).
>>>
>>>So what are your requirements regarding autonumbering and label 
>>>collisions?
>>>
>>>-Steve W.
>>
>>
>>If I understand what you're asking, I think we want to show all labels
> 
> 
>>all the time, even if they collide.  Or even if some hid others, we 
>>wouldn't want to re-order the numbers.
>>
>>Doug
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