to handle creation of parameter definition widgets
Previously, these configuration widgets were all hardcoded into the Python modeler
dialog. This prevented 3rd party, plugin provided, parameters from ever being full
first class citizens in QGIS, as there was no way to allow their use as inputs to
user created models to be customised.
Now, the registry is responsible for creating the configuration widget, allowing
for 3rd party parameter types to provide their own customised configuration
widgets.
Refs #26493
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.
And add a Processing setting to allow these to be shown. When shown, they
are highlighted in red with a tooltip explaining that the algorithm
has known issues
This adds a new "Model Variables" dock panel to the model editor, allowing
users to create and set custom expression variables for use in the model.
These variables are available anywhere expressions are (correctly) evaluated
within the model, so can be used as input parameter values for child
algorithms, within data-defined dynamic parameters, etc.
The use case here is for models which use a constant value throughout
multiple steps within the model (e.g. @target_resolution: a target
raster resolution, @max_simplification: a simplification value for
input features coming from different sources, etc), allowing users
one single place to define and edit these constant values (instead
of hunting down and setting them in multiple places throughout the model).
These variables are stored within the model itself, and are not exposed
outside of the model designer dialog.
Brings back QGIS 2.18's ability to directly convert a Processing model
to an equivalent Processing Python script algorithm, correctly
updated and working in the 3.x API.
Available from the model dialog, and from the right-click context
menu on an existing model.
Sponsored by Solspec
- fix parameter can get converted to plain number parameter after edits
- allow parameter to be linked to parent parameters, so that the
correct distance unit and choices are shown for the parameter
data defined buttons for model child algorithms
The context was not previously exposed, so users would not have
been aware that they can utilise all the variables and functions
available to parameters within child algorithms.
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.
