[udig-devel] Re: More questions about expressions and styles

["Matthias Basler" <matthiasbasler@xxxxxxxxxxxxxxx>]

Hi GeoTools community, hi Jody,

I am making my way through the current GeoTools styling API and noticed a few strange things about which I want to complain ... err, I mean, I'd like to ask some innocent questions. ;-)

1. All values within styles are expressions. All? No, there seem to be a few exceptions, for whatever reason. Please try to explain to me why
    org.geotools.styling.Stroke
has following method signatures (among others)
    Expression getDashOffset();
    float[] getDashArray();

If I interpret this correctly, the dash offset may vary depending on the feature while the dash array is the same by definition. Doesn't make sense to me...

As another example, the point symbolizer contains Marks and/or Symbols, actually two equivalent things with different implementations (vector vs. raster).
The interface "Mark" has the signature
    Expression getWellKnownName();
whereas the interface "Symbol" has no such method the subinterface "ExternalGraphic" has the method
    URL getLocation()
Again, the former is a potentially variable expression the latter a literal by definition. Why?


2. I infer from the interface source code that a "Graphic" contains (among others) size, rotation and several marks. The "Mark" interface defines size and rotation again for this mark.
That's redundant information, isn't it? Actually the "Mark" interface doesn't comment on size and rotation in it's Javadoc, and the functions look like they were added afterwards, possibly as a "quick hack" for somebody.

Now assume I get a graphic where the graphic tells me the size is 32 pixels and the marks within tell me they want to be drawn with a size of 24 pixels. Who should I believe?

So far so good. These are just minor issues, but I thought I should mention them anyway.
-- 
Matthias Basler
matthiasbasler@xxxxxxxxxxxxxxx