This feature allows for expressions to be embedded directly inside
legend item text (e.g. group, subgroup and item text). The expressions
are evaluated at render time, with full knowledge of the legend's
expression context (so can utilise variables from the layout/layout item/
etc)
There's no UI for this yet (that will come in 3.8), but expressions are
entered using the standard [% 1 + 2 %] format.
E.g. a legend item text of
My layer (rendered at 1:[% @map_scale %])
will show in the output as
My layer (renderer at 1:1000)
Adds new variables for use in data defined expressions for layout legend items, including
- @legend_title
- @legend_column_count
- @legend_split_layers
- @legend_wrap_string
- @legend_filter_by_map
- @legend_filter_out_atlas
Additionally, if the legend is linked to a map, then expressions used in that legend will also have access to the linked variables, including @map_scale, @map_extent, etc.
Similarly to raster calculator, mesh calculator can take dataset groups from current mesh layer and
combine them with various aritmentic/logical operators to new dataset group.
at the antimeridian
Whenever line segments in the input geometry cross the antimeridian, they
will be split into two segments, with the latitude of the breakpoint being
determined using a geodesic line connecting the points either side of this
segment.
If the geometry contains M or Z values, these will be linearly interpolated
for the new vertices created at the antimeridian.
and asMultiPolygon()
- raise ValueError when these methods are called with null geometries
- raise TypeError when these methods are called with incompatible
geometry types, instead of silently returning empty lists
This allows nice and simple, elegant construction of checks for
Python.
To use, Python based checks should use the decorator syntax:
from qgis.core import check
@check.register(type=QgsAbstractValidityCheck.TypeLayoutCheck)
def my_layout_check(context, feedback):
results = ...
return results
Or, a more complete example. This one throws a warning when attempting
to export a layout with a map item set to the Web Mercator projection:
@check.register(type=QgsAbstractValidityCheck.TypeLayoutCheck)
def layout_map_crs_choice_check(context, feedback):
layout = context.layout
results = []
for i in layout.items():
if isinstance(i, QgsLayoutItemMap) and i.crs().authid() == 'EPSG:3857':
res = QgsValidityCheckResult()
res.type = QgsValidityCheckResult.Warning
res.title='Map projection is misleading'
res.detailedDescription='The projection for the map item {} is set to <i>Web Mercator (EPSG:3857)</i> which misrepresents areas and shapes. Consider using an appropriate local projection instead.'.format(i.displayName())
results.append(res)
return results
Better to use QVector here, because the QgsLineString/QgsGeometry
methods all use QVector too, and we want to avoid unnecessary
list->vector conversions.
