[mapserver-dev] Request for review/comments on RFC 77 (multiple label support)

Lime, Steve D (DNR) Steve.Lime at state.mn.us
Tue Dec 13 11:37:26 EST 2011

1.       I don't think it's possible to handle multiple priorities within a group, that defeats the point of the group (all or nothing display). I could see a later enhancement to allow labels to be explicitly grouped or excluded from a group. I think we'd need a compelling use case to introduce that level of complexity.

2.       To fit labels with in a polygon we'd probably need introduce a new bit of configuration (e.g. POSITION FIT). You'd have to consider the labels as a group in that case which would probably be quite difficult. I'd treat this case sorta like labeling lines in general.

3.       Good suggestion. Offhand:

a.       3009: No impact.

b.      2981: No impact.

c.       3335: Styles are supported for each additional label.

d.      2866: No impact.

e.      1355: Wow, an old one, wonder if that's even valid anymore. No impact, the cache object contains a polygon that represents all labels in the group (if grouped).

From: Brent Fraser [mailto:bfraser at geoanalytic.com]
Sent: Tuesday, December 13, 2011 10:13 AM
To: Lime, Steve D (DNR)
Cc: mapserver-dev at lists.osgeo.org
Subject: Re: [mapserver-dev] Request for review/comments on RFC 77 (multiple label support)


Looks very promising.  A few points:

1. Label priority within a group.  Someone may want to assign priority to labels withing the group ("always (try to) label the well_id, and label the well_production if there is room").   I guess this could be handled with the current method of using two LAYERs with different label PRIORITY.

2. Allow for alternate label positions.  While this is likely beyond the scope of the RFC, perhaps it could be taken into account in design and implementation for later addition.  Basically I'd like more flexibility (rule-based?) in labeling polygons:

    A. Try to place label in polygon.  If it doesn't fit:
    B. Rotate anno to fit inside a polygon.  If it doesn't fit:
    C. Place polygon annotation outside polygon

3.  I think we need a section in our RFCs for related Tickets.  E.g.:

http://trac.osgeo.org/mapserver/ticket/3009    getLabelPoint() does not work for polyline and point layers.
http://trac.osgeo.org/mapserver/ticket/2981    Need a way to define a POSITION array for labeling.
http://trac.osgeo.org/mapserver/ticket/3335    Label style support
http://trac.osgeo.org/mapserver/ticket/2866    Drawing 'Straight' label with LABEL_NO_CLIP, if 'Follow' label drawing fails.
http://trac.osgeo.org/mapserver/ticket/1355    labelInImage and buffer usage

and indicate if/how the RFC will impact the tickets.


Best Regards,

Brent Fraser

On 12/12/2011 9:14 PM, Lime, Steve D (DNR) wrote:
Hi All: I'd like to request some review on a pending RFC regarding support for multiple label objects within a class. Please see http://mapserver.org/development/rfc/ms-rfc-77.html. Thanks!



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