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)
This line symbol type is designed to replicate the ArcGIS Hash Line
symbol layer type. It allows for a repeating line segment to be
drawn over the length of a feature, with a line-sub symbol used
to render each individual segment.
To reduce code duplication, this is heavily based off the current
line marker symbol layer, since the functionality is almost
identical (draw some sub symbol at some interval along a line).
Accordingly, I've split off QgsMarkerLineSymbolLayer to move
as much of the common functionality as possible to a new abstract
base class, so that only the actual marker/line segment rendering
occurs in the marker line/hash line subclasses.
This also gives the hash line all the existing placement options
permissible for marker lines -- e.g. first/last vertex, mid points,
regular intervals, etc.
The hash line length and angle can have data defined overrides,
which are evaluated per-line segment, allowing for the hash line
to change size and angle over the length of a single rendered
feature.
K-nearest neighbour joins from the Processing toolbox!
This algorithm takes an input vector layer and creates a new
vector layer that is an with additional attributes in its attribute table
The additional attributes and their values are taken from a second
vector layer, where features are joined by finding the closest features
from each layer.
By default only the single nearest feature is joined, but optionally
the join can use the n-nearest neighboring features instead.
If a maximum distance is specified, then only features which are
closer than this distance will be matched.
nearest neighbor search based on QgsGeometry to QgsGeometries
Previously only point - geometry was possible. But with this
change, you can safely and accurately use QgsSpatialIndex
to determine the nearest neighbours between any types of
geometries.
