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.
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.
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.
Adds label distance factor spinbox to Point Displacement symbology
window. Calculates label distance based on the current symbology
diagonal instead of a general maximum diagonal.
Replaces the hard coded distance "symbolDiagonal/2.0" with
"symbolDiagonal*mLabelDistanceFactor", where mLabelDistanceFactor is set
to the spinbox value.
It's an old feature request (Point displacement labels adjustable
offsets "https://issues.qgis.org/issues/5945").
Partly reverts c9e761649, which removed the synchronizatiion of
credential requests (eg. in a project that has multiple layers from the
same postgresql database without credentials) and led to multiple
concurrent requests for the same credentials.
Some of which were silently discarded, when events processed in the
dialogs exec() event loop tried to reinvoke the dialog and caused
invalid layers.
Authentications caused by network requests can still cause this.
The credential cache is now guarded by a separate mutex.
