Re: [Geotools-devel] uom scale in target device size?

[Ákos M. <ak...@ma...>]

Andrea,

Another issue came up with uoms, and this is also not specific to
device-size uoms, but with any uom already defined earlier. This is the
case of expressions, or rather, when using constants in expressions.

Consider for example the following:

    <sld:PolygonSymbolizer uom="http://www.opengeospatial.org/se/units/metre">
        <sld:Geometry>
            <ogc:Function name="buffer">
                <ogc:PropertyName>way</ogc:PropertyName>
                <ogc:Literal>300</ogc:Literal>
            </ogc:Function>
        </sld:Geometry>
        <sld:Fill>
            <sld:CssParameter name="fill">#FF0000</sld:CssParameter>
            <sld:CssParameter name="fill-opacity">0.4</sld:CssParameter>
        </sld:Fill>
    </sld:PolygonSymbolizer>



one would assume that the above would create a buffer of the polygon at
hand, with a 300m (real-world) distance from the original polygon. but,
what the current code does is that the buffer is 300 pixels from the
polygon. now, there is a simple omission in the code, in
UomRescaleStyleVisitor.visit(PolygonSymbolizer), the polygon's geometry
is not rescaled.. but even if one adds the following line:

rescale(copy.getGeometry(), mapScale, dpi, copy.getUnitOfMeasure());


the results is not what one would expect. the result of the above line
is basically equivalent to:

        <sld:Geometry>
            <ogc:Mul>
                <ogc:Function name="buffer">
                    <ogc:PropertyName>way</ogc:PropertyName>
                    <ogc:Literal>300</ogc:Literal>
                </ogc:Function>
                <ogc:Literal>scale_factor</ogc:Literal>
            </ogc:Mul>
        </sld:Geometry>


which doesn't bring the desired result.

I wonder if this issue has been considered, and what the general
acceptance would be if one would implement a fix so that all literal
values inside such expressions are scaled, according to the uom scaling
factory.

best regards,


Akos