On Feb 18, 2009, at 12:15 AM, Steve Lime wrote:
I did notice when poking around in the source that the labelling
routines didn't know about the geometry of individual features. In
my
own early (v4.4) attempts at reordering the positions for polys
(before the recent changes) I added a parameter to the addlabel()
functions to pass the shapetype.
I think I'd just pass a shapeObj pointer to the msAddLabel() and
harvest
what is necessary: type and a few indexes.
If you think this is something that can be done, it would be nice have
geometry and annotation layers both use the same positioning rules
based on the geometry type (see comments below).
I'm not sure what you mean here - how does label priority invalidate
annotation layers?
The principle reason to use annotation layers was to control the
order in
which labels are stuffed into the cache. They were especially useful
with
polygons since you typically draw those first but if you want to
emphasize
labels then you'd have to use annotation to make the labels show
before
other stuff.
Label priorities fix that. You can give a polygon layer high
priority labels
without having to resort to annotation layers later in the mapfile.
The benefits
(besides working around this bug) are two-fold:
1) performance, you only have to process the polygon features once...
2) brevity, shorter, more concise layer definitions are good...
Certainly annotation layers are still useful but principally for
things like
copyright notices or road shields.
Steve
Hmm, but mixing the annotations with their geometry in a single layer
means you can't turn geometry and annotations on and off separately -
I often want to show just the feature geometry, yet be able to turn on
their annotations if I need it.
Also, what about the drawing order? Won't other feature layers then
draw on top of earlier feature layers and annotations of those
layers? Or does the label cache force ALL annotations to draw last,
no matter what layer they're on?
I guess I need a visual diagram of the [now many] various possible
combinations of layer types, annotations, priorities and layer
ordering to make sense of this.
-----
William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
http://www.kyngchaos.com/
"Time is an illusion - lunchtime doubly so."
- Ford Prefect
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