Usually a geometry generator expression must return a geometry
in the associated layer's CRS. But this doesn't work in situations
where a geometry generator symbol is NOT associated with a layer,
e.g. when used in a layout item.
So add a new option to allow users to specify which unit the expression
will return geometries in, with choices of map units (the default,
previous behavior), millimeters, pixels, inches and points.
When millimeters, points, inches or pixels is selected then
the @map_geometry variable will be available for the expression,
and contain the feature's geometry in the specified units (relative
to the map frame). (The $geometry variable remains available and
still in layer CRS, in case an expression needs to calculate the
original area, perimeter, etc in real-world units while returning
results in a different unit!)
A step toward fixing #39159
- Add enums to qgis.h instead of qgscoreenums, so that they belong to
a Qgis namespace
- Split up the various symbol headers into multiple files so that we
can fine-tune their inclusion and forward declare more readily, speeding
up recompilation
- Move QgsSymbol enums to qgis
