This adds a new parameter type specifically for map scales,
QgsProcessingParameterScale. The values are evaluated using
self.parameterAsDouble, which returns the map scale
denominator (matching the standard in other parts of the
QGIS API).
Scale parameters are displayed to users using the standard
QgsScaleWidget, which includes the combo box of predefined
scales and a shortcut button to match the current map scale.
Returns a descriptive list of the possible string values acceptable
for the parameter.
E.g. for a QgsProcessingParameterVectorLayer this may include
"Path to a vector layer", for QgsProcessingParameterBoolean
"1 for true, 0 for false" etc.
For the c++ api dox this expands to "\c nullptr" (the
\c directive indicates a code literal value), and for sipify/Python
it expands to ``None`` (`` is sphinx annotation for literal values)
Makes for nicer dox for both c++ and Python!
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.
This adds a new available parameter type for processing algorithms,
QgsProcessingParameterAuthConfig, allowing selection from available
authentication configurations (and creation of new ones).
It allows creation of processing algorithm which can fully take
advantage of QGIS' mature authentication handling, avoiding the
need to use insecure string parameters for users to input
sensitive logon credentials.
QgsProcessingParameterAuthConfig parameters are evaluated using
QgsProcessingAlgorithm.parameterAsString(), which returns the
selected authentication configuration ID.
to show in numeric/distance widgets
E.g. to only show 2 decimal places:
# only show two decimal places in parameter's widgets, not 6:
param.setMetadata( {'widget_wrapper':
{ 'decimals': 2 }
})
And require that showing help is opt-in. Apart from a handful
of built-in providers, most providers will not have help pages
available within the QGIS documentation (including model and
script algorithms). Accordingly, we should hide the help button
by default and only show it for these selected providers.
Note that 3rd party algorithms can still specify custom helpUrl
urls, in which case the button WILL be shown.
A new widget which handles parameter values for child algorithms
within a model. Instead of the previous approach of requiring
individual widget wrappers to handle creation of a suitable
model widget, we do all this automatically for them.
This widget uses a stacked widget with a toolbutton to select
the parameter's source, instead of the previous combo box approach
(which didn't scale well for large models). I.e. users select
first whether the value is taken from a static value, a
model input, or an output from a different child algorithm. The
widget then changes appearance and behavior based on this
choice.
Additionally, a new option is present for all parameters
of using a "precalculated expression". This expression is
evaluated once before the child algorithm is executed
and used during the execution of that algorithm.
