layers which have been set for a canvas but which AREN'T part of
QgsProject::instance()
Required to fix test failure in labeling map tools, but ultimately
a necessary piece of API to ensure that map tools aren't so tightly
bound to QgsProject::instance()
Accessible via QgsGui::recentStyleHandler(), this is intended as
a place to store recently used style items (e.g. symbols).
Initially it's used just for annotation items so that newly
created annotation items are automatically set to the same style
as the most recently modified item of the same type (e.g. so
that users drawing many point annotations don't need to keep
setting it back to the same appearance)! But the api is kept
flexible for additional uses in future... (eg layout items)
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
This code corresponded to a "not a vector layer" error, which needlessly
prevents the QgsMapToolCapture class from being usable as a base class
for map tools which operate on non-vector layers.
There's no reason to restrict this call solely to vector layers
-- it's useful to have accessible for adding geometries associated
with other layer types too.
If we require all annotation item map tools to inherit from
QgsMapToolAdvancedDigitizing, then we lose the flexibility to
subclasss other map tools for annotation item creation (e.g.
QgsMapToolCapture)
