For stable API use only, and then cleanup the private version
of this to remove all the consideration of 3.0 API compatibility.
Mark the archive copy as deprecated and remove in 4.0
This method has become completely unweildy because of all the
compatibility code. By making this private only we can rip
out all this old code and make the method much simpler and
easy to understand.
See https://github.com/qgis/QGIS-Enhancement-Proposals/issues/299
Implements the API framework for setting advanced labeling engine
rules for a project, and implements 4 initial rule types:
- QgsLabelingEngineRuleMinimumDistanceLabelToFeature: prevents labels
being placed too *close* to features from a different layer
- QgsLabelingEngineRuleMaximumDistanceLabelToFeature: prevents labels
being placed too *far* from features from a different layer
- QgsLabelingEngineRuleMinimumDistanceLabelToLabel: prevents labels
being placed too close to labels from a different layer
- QgsLabelingEngineRuleAvoidLabelOverlapWithFeature: prevents labels
being placed overlapping features from a different layer
(note that the first 3 rules require a build based on GEOS >= 3.10,
they are not available for older GEOS builds)
Also implements a registry for storing available rule classes,
and serialization of rules and configuration in QGIS projects
For the "Around point" and "Cartographic" placement modes, this
adds a new optional setting for the maximum distance of the labels from
the feature. It's used together with the existing distance setting
to define a range of distances at which labels may be placed
from their corresponding point features.
This adds more flexibility to the placement for these layers,
ultimately allowing for more labels to be placed in busy maps.
When the layer is set to the "around point" mode, then label
candidates which are closer to the point will always be prefered
over those which are further away.
When the layer is set to the "cartographic" mode, then the default
behavior is also to prioritize closer labels. A new combo box
allows users to control the priority, with an option for
prefering position ordering. If this option is set, then candidates
at the corresponding positions (eg top left) are preferred regardless
of how far they are from the point, with the labelling falling
back to alternate positions only when no labels can be placed
up to the maximum label distance.
Sponsored by Rubicon Concierge Real Estate Services
The old sip based approach to handling property -> getter/setter
conversion is broken on sip6, so move the patching into Python.
Also fix incorrect checks in tests, and add additional test
for compatiblity code.
Shows the text bounds of the label in red and baselines in blue.
Designed for debugging purposes only.
Also move label engine enums to Qgis, promote to enum class
- Move settings to be feature level, not layer level, and permit
data defined control of these settings
- Add additional option for overlap handling for "Always allow"
overlaps, which indicates that the user doesn't care at all
if the label overlaps other labels and that the ideal placement
should always be used for the label regardless of whether it
overlaps labels or not
To clarify further, the options are:
- Never Overlap : never ever place overlapping labels for the layer,
even if it means labels will be missing
- Allow Overls if Required: if the label can't otherwise be placed,
draw an overlapping label. This mode will cause the label to be moved
a less ideal placement if possible, e.g. moving the label further
from the center of a line or polygon, IF doing so will avoid overlapping
labels. But if there's no other positions possible, then draw the
label overlapping.
- Always Allow Overlaps": It doesn't matter at all if the label
overlaps other labels or obstacles, that's fine to do and the best
placement (e.g most central placement) should always be used even if an
alternate further placement is possible which avoids overlaps entirely.
