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.
This adds a second variant for the existing "attribute" function.
The current function requires both a target feature and attribute
name to be specified, while the NEW variant just uses the current
feature.
E.g.
NEW:
attribute( 'name' ) -> returns the value stored in 'name' attribute
for the current feature
EXISTING:
attribute( @atlas_feature, 'name' ) -> returns value stored in 'name'
attribute for the current atlas feature
It's just a faster shorthand version!
OTB only supports gdal and ogr providers for now. Maybe memory
provider can be easily supported using some conversion on the fly.
For the moment, we can go with this method. IO Formats in OTB not
using GDAL/OGR (LUM, ONERA) are not supported by QGis. Those can be
treated as simple files.
nyalldawson, pointed that AUTHORITY id can have types not starting
with 'EPSG:'. Current otb takes just EPSG number and run with it. The
algorithm doesn't know what to with a number which is not EPSG because
it uses Gdal's 'ImportFromEpsg' method AFAIR.
QgsProecessing Exception is raised in both the above invalid cases.
This can easily go into GuiTests.py but we tend to keep it out due to
usage of create_from_metadata(). All widget in GuiTests uses
create_from_class() which will not work for this special widget
