... and add a getter for coordinateTransform to QgsMapLayer
The reason is that I think we should reduce the dataProvider API
usage and rely on the higher level QgsMapLayer API whenever it
is possible, QgsMapLayer checks for data provider validity
and returns a default constructed QgsCoordinateTransform instead
of crashing.
which will be available to a parameter when it is evaluated.
Specifying variables via this method is for metadata purposes only.
It is the algorithm's responsibility to correctly set the value of
these additional variables in all expression context used when evaluating
the parameter, in whichever way is appropriate for that particular variable.
In OGC WMS standard, the empty string represents the default style.
QGIS Server when it parses the parameters, QGIS Server when it parses parameters it removes empty parts.
When all requested styles are default ones it's equal to an empty parameter STYLE, as defined in the standard.
When only one layer is requested, there is no issue with custom or default style.
When multiple layers are requested and some with custom styles, because QGIS Server does not retain empty strings, it loses the layer / style match.
To fix it, keeps empty parts for not empty styles parameters.
Previously, when marker or hash lines were rendered using interval
or center point place placement, the symbol angles were determined
by taking the exact line orientation at the position of the symbol.
This often leads to undesirable rendering effects, where little
jaggies or corners in lines which occur at the position of the
symbol cause the marker or hash line to be oriented at a very
different angle to what the eye expects to see.
With this new option, the angle is instead calculated by averaging
the line over a specified distance either side of the symbol. E.g.
averaging the line angle over 4mm means we take the points along
the line 2mm from either side of the symbol placement, and use these
instead to calculate the line angle for that symbol. This has the
effect of smoothing (or removing) any tiny local deviations from
the overall line direction, resulting in much nicer visual
orientation of marker or hash lines.
Like all symbol settings, the average angle smoothing distance
can be set using mm/pixels/map units/etc, and supports data-defined
values.
Closed rings also correctly consider wrapping around these average
angles from the start/end vertex.
(Sponsored by an anonymous corporate backer)
