This is a subclass of QgsProcessingParameterNumber, but specifically
for numeric parameters which represent distances. It is linked
to a parent parameter, from which the distance unit will
be determined, and is shown using a dedicated distance widget
within the processing parameters panel. This widget shows
the distance unit.
This avoids the confusion when running algorithms which
use distances where the unit depends on a layer or CRS parameter -
e.g. the distance parameter in the buffer algorithm gives
the distance in layer units... so now we can show those units
directly within the dialog. Hopefully this leads to less
user confusion and accidental "1000 degree buffers"!
Additionally - if the unit is in degrees, a small warning
icon is shown next to the parameter. The tooltip for this
icon advises users to reproject data into a suitable
projected local coordinate system.
Initially implemented for the native buffer and single
sided buffer algorithm only - but more will be added.
Fixes#16290
Aside from the performance benefits, the Python version of this
algorithm occasionally fails on Travis with odd errors. Hopefully
by porting to c++ it will fix these, or at least give useful
debug information in the event of a fail.
Also add support for curved input geometries.
- Output interpolated points when travel cost falls mid-way along
an edge
- Output all intermediate reachable points also
- Make outputting upper/lower bound points optional, and non-default.
Now by default we just output all definitely reachable points and
the interpolated points along edges which correspond to the travel cost.
This allows the output to be used to correctly generate service areas
e.g. by concave/convex polygons and all reachable nodes will be
included in the area.
- Allow algorithm to optionally output a line layer (and make the
point layer optional too, and default to just the line layer output)
containing all reachable line segments (including interpolated
segments of lines when the travel cost sits midway along that
edge). This output is more easily understandably for users.
Instead of returning a single QgsFeature from processFeature, we now
return a list of features.
This allows feature based algorithms which return multiple features
per input feature, e.g. "explode" type algorithms which split a
single input feature into multiple output features.
always add a consistent amount of attributes regardless of the
code paths taken
Some algorithms were adding features to data providers with
different number of attributes vs the layer's fields - this is
not supported and depending on the data provider will have
different (bad) results.
be prepared
There's cases where this happens without reflecting an invalid
expression. So we can try to prepare, but not abort if the
preparation fails.
Fixes#18103
- Fix missing format call for string when calculated number
of points is 0
- Fix incorrect progress reports which were spamming the dialog
and causing UI hangs, and slow algorithm execution
