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
options should be available for certain model outputs and script
algorithm outputs
We do this by swapping the test for non-file based output support
from checking only the algorithm's provider to instead checking
on a parameter-by-parameter basis.
This is done in order to support models. For models, depending
on what child algorithm a model output is based off, an individual
model may or may not have support for non-file based outputs. E.g
a model may generate outputs from a native qgis alg (supporting
these outputs) AND an output from a GDAL alg (with no support
for these outputs). In this case we need to enable or disable
the ui controls for non-file based outputs on an individual
output basis.
For scripts (for now) we blindly just say all outputs support
non-file based formats. This is going to be the case most of
the time, since scripts will usually be written using PyQGIS
API. For the exceptions (e.g. scripts which call other algs
like GDAL algs) we probably should add some way for the script
to indicate whether an individual output supports this, but
for now we just say they all do.
Fixes#17949
