Replace with just f[idx]. Calling QgsFeature.attributes()
allocates a list of all attributes, which is inefficient
when only a single attribute value is needed.
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.
This implements an improved version of vector.createVectorWriter
in QgsProcessingUtils. The improved version relies on the
core class QgsVectorLayerImport to create empty layers,
which:
- reduces duplicate code and reuses the mature QgsVectorLayerImport
routines
- avoids manual conversion of field types to destination provider
field types
- potentially allows any writable provider to be used as a feature
sink for algorithms (e.g. output direct to MSSQL/Oracle/db2). This
should work now - it just needs exposing via UI.
Algorithms and other processing code should use this method
(instead of dataobjects.getLayerFromString) to
retrieve layers from a string, as it considers the processing
context and allows resolving strings to temporarily stored layers.
This permits processing models to function correctly when
intermediate results are stored as memory layers. Subsequent
model algorithms can then access these temporary layers as inputs.
All temporary layers will be removed when the context object
is destroyed after the model algorithm is run.
Remove processing vector.uniqueValues/vector.getUniqueValues
and port usage to c++ method
Should be much faster than the python method, as the c++ method takes
advantage of handing off the unique values calculation to the
provider source whenever possible
Instead rely on QgsFeatureRequest method. There's a temporary
loss of the feedback on encountering an invalid geometry
when abort on invalid is set, but that will be resurrected
when all of vector.features is moved to c++
- setEllipsoidalMode() was removed. Ellipsoidal calculations are
now enabled whenever a valid ellipsoid() has been set. Set the
ellipsoid to 'NONE' to disable ellipsoidal calculations.
- ellipsoidalEnabled() was removed. Ellipsoidal calculations
are now enabled whenever a valid ellipsoid() is set. Check
willUseEllipsoid() to determine whether ellipsoidal
calculations will be performed.
- sourceCrs() and setSourceCrs() now always take and return
QgsCoordinateReferenceSystem objects. All string/ID based CRS
methods were removed.
- geographic() was removed. This was only used internally
in one place, so was replaced with sourceCrs().isGeographic() instead.
- some largely overlapping measurement functions were consolidated
Also
- simplify and add tests
- remove large memory leak (persistant store of all non-project layers)
- remove broken support for direct loading postgres/virtual layers
by string (Python version was very broken and would never match
a postgres/virtual layer)
