Adds processing.createAlgorithmDialog and
processing.execAlgorithmDialog. These methods can be used
to create and execute algorithm dialogs for a specified algorithm,
optionally pre-populated with a given set of (non-default) parameter
values.
* A new createopt textbox has been added to the parameters dialog for algorithms which exports to raster files.
* A new metaopt textbox has also been added to the Algorithm parameters dialog.
* Raster file format is detected from output filename extension.
* GdalUtils has been improved to correctly detect raster formats supported for creation.
* QFileDialog for output rasters now display only file filters for supported output raster file formats.
Rationale:
- the correct use for this option is unclear, and users are
mistakenly using it as a 'tolerance' option
- it's very likely to generate invalid geometries as a result
of the snapping, causing unreliable results
Given these substantial issues, it's safer to remove this
option and require that users who need the snap to grid
precision change explicitly do this via an extra model
step before running the algorithm.
initAlgorithm() method
This allows 2 benefits:
- algorithms can be subclassed and have subclasses add additional
parameters/outputs to the algorithm. With the previous approach
of declaring parameters/outputs in the constructor, it's not
possible to call virtual methods to add additional parameters/
outputs (since you can't call virtual methods from a constructor).
- initAlgorithm takes a variant map argument, allowing the algorithm
to dynamically adjust its declared parameters and outputs according
to this configuration map. This potentially allows model algorithms which
can be configured to have variable numbers of parameters and
outputs at run time. E.g. a "router" algorithm which directs
features to one of any number of output sinks depending on some
user configured criteria.
The previous naming was too easily confused with processing outputs.
Rename them to QgsProcessingParameterFileDestination, etc... to
make it clearer what they are used for.
