Non-clipped polygon annotation
Steve.Lime at DNR.STATE.MN.US
Mon Dec 17 19:51:10 EST 2007
Cool! I was planning on doing this myself. I even had it working but I inadvertently deleted
that branch doing some house keeping and haven't had time to recreate. Couple of comments:
- I'd go with an easier to understand processing key, perhaps LABEL_PRE_CLIP?
- there are 2 places to apply this (for polygons), for ANNOTATION layers and for POLYGON layers
- should be implemented for LINE layers as well
For some reason I remember being able to do this without doing a shape copy. I believe I intervened
before clipping and generated the label point and then referenced that point if a flag was set.
Basically msPolygonLabelPoint() was run before the clip (if the processing key was set) and
then not afterwards (or vice versa). I think you'd get better performance avoiding the copy.
>>> On 12/17/2007 at 6:22 PM, in message <476712C7.7010403 at project10.net>,
project10 <project10 at PROJECT10.NET> wrote:
> Hi devs,
> I've implemented support for an item that was discussed on IRC last week
> - annotating polygons based on their pre-clip shape. This gives fixed
> label positioning for polygon layers without the need to precompute an
> annotation point based on the polygon centroid.
> Frank suggested that I commit my ideas to a proper RFC format, but I
> wanted to first get some feedback from you guys.
> The patch adds support for a NOCLIPANNO processing directive at the
> layer level. If the processing option is enabled, it will copy the
> polygon shape pre-clip and use that to determine annotation points. If
> not given, the old behavior is used.
> My initial implementation is at http://rafb.net/p/4wGaHV10.html
> Some renders showing the behavior change:
> http://project10.net/ms/normal.png - current behavior
> http://project10.net/ms/normal-myissue.png - Why I didn't like the
> current behavior. My labels get 'dragged around'.
> http://project10.net/ms/annoclip-inview.png - Labeling of a polygon with
> my change
> http://project10.net/ms/annoclip-demo.png - If the map is panned, the
> annotation point stays fixed, even though part of the shape it annotates
> is now clipped.
> http://project10.net/ms/annoclip-partials.png - It also plays nice with
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