Because feature.geometry().geometry() is confusing, and impossible
to search for in python code (e.g. is input.geometry() a QgsGeometry
or a QgsAbstractGeometry?)
But more importantantly: also add a const version
QgsGeometry::constGet(). The non-const
version is slow, since it now forces a detach to avoid corrupting
geometries (since QgsGeometry is shared, it's not safe to directly
access its primitive QgsAbstractGeometry and start messing with
it without first detaching). This is a big risk in the 2.x API
which could potentially corrupt feature geometries with unexpected
outcomes.
Update all uses to constGet where possible.
By moving logic to abstract geometry subclasses so that they
can trivially retrieve the vertex number, instead of relying
on the inefficient coordinateSequence method.
Has flow on speed boosts to many geometry operations like
calculation of closest points in a geometry, which will
benefit snapping related operations.
Previously the method in QgsGeometryUtils was relying on
QgsAbstractGeometry::coordinateSequence, which is an absolute
performance killer.
Instead move to optimised methods in the various abstract
geometry subclasses which rely only on trivial calculations.
Introducing:
1. STL-style iterator: QgsAbstractGeometry::vertex_iterator
2. Java-style iterator: QgsVertexIterator (built on top of STL-style)
The iterators are modeled after Qt's STL-style and Java-style iterators,
the idea is to replace nextVertex() method and later introduce iterators
for other bits (e.g. part_iterator, ring_iterator).
Faster than QgsGeometry::isGeosEmpty() because it avoids the
conversion to GEOS geometries and just uses the QgsAbstractGeometry
subclasses directly.
Also implements faster isEmpty() overrides for specific
QgsAbstractGeometry subclasses.
Make nCoordinates virtual, and provide shortcuts for some
geometry types. The base method which calls coordinateSequence()
is quite slow in certain circumstances.
Speeds up rendering point layers by ~25%, also likely to
speed up lots of geometry heavy operations throughout QGIS
Refs #15752
