render exterior ring or interior rings
This option is shown whenever a simple line symbol or
marker line symbol is used as part of a fill symbol for
rendering polygons.
The default behavior is to render both interior and exterior
rings, but this new setting allows users to set the symbol
layer to render only for the exterior ring OR only
for interior rings.
This allows for symbolisation which wasn't directly possible
before, such as a marker line with markers for interior
rings angled toward the interior of the polygon.
Sponsored by the German QGIS User Group
Fixes#12652
This new option, available under the "Advanced" button for fill symbols,
allows forcing rendered polygons to follow the standard "right hand
rule" for ring orientation (where exterior ring is clockwise, and
interior rings are all counter-clockwise).
The orientation fix is applied while rendering only, and the original
feature geometry is unchanged.
This allows for creation of fill symbols with consistent appearance,
regardless of the dataset being rendered and the ring orientation
of individual features.
Refs #12652
Added a check for layer.isValid in relation.isValid, keep
relations in the manager even if they are not valid and
connect dataSourceChanged with updateRelationStatus
... and to count them
Tests updated accordingly, note that from now on
the assumption that a layer store or a layer project
contains only valid layers will not be true anymore.
To be honest it has never been true, because a
layer can become invalid at any time during
its life cycle, so better never assume that a
layer from the store or from the project is vaid.
This can be used to restore initial layer status or to
apply styles and other layer properties if the data
source is changed.
The idea is that the user can fix bad layers at any time,
and by setting a new datasource she probably wants
to keep the original layer properties.
These providers will be used to control how the browser data items
behave within GUI, and to allow separation of GUI related
properties of browser items from the core code.
A new registry QgsDataItemGuiProviderRegistry has been created
(modeled off QgsDataItemProviderRegistry), with an application
wide instance available from QgsGui::instance()->dataItemGuiProviderRegistry()
