And:
- fix enable state of selected features only after changing between
map layers with/without selections
- fix state of selected features only when running an algorithm
from the history list, e.g. respect original setting for
selected features only (or not)
- ensure no duplicate changed signals are sent, and correctly
emit changed signals in all applicable circumstances
- handle drag and dropped layers from browser panel (UX fix)
- soak with unit tests
Instead of requiring clients to generate temporary file names themselves,
(or use the cryptic "memory:" string!), this PR adds a static constant
QgsProcessing.TEMPORARY_OUTPUT
If a layer/sink output parameter is set to QgsProcessing.TEMPORARY_OUTPUT,
then the temporary output filename will be generated automatically at
algorithm run time. This means callers don't need to mess around with
finding appropriate temporary folders and paths.
Another benefit is that TEMPORARY_OUTPUT is stored in the processing
history, so if you re-run a previous algorithm which was set to
output to a temporary file, it no longer tries to use that same
previous temporary path and instead generates a new one.
When an algorithm has a distance parameter in meters/feet/etc (i.e.
non-geographic distances), show a combo box allowing choice of
unit type.
(We don't (and should never) expose this for distances in degrees --
it's up to users in this situation to choose a suitable local
projection and reproject their data to match. Refs: a recent
talk by @volaya)
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
