Implement WsiAnnotations in C++

[jonasteuwen]

The WsiAnnotations have been rewritten using boost.Polygon, replacing shapely. The current implementation with shapely has a few issues:

• complicated dependencies (GEOS)
• if you subclass shapely geometries and apply operations on them, they return the shapely polygon, and not your subclass.

The proposal is to keep WsiAnnotations around until v1.0.0, add deprecation warnings to the current calls that are not 1-1 compatible with the new SlideAnnotations (available in dlup.annotations_experimental). In particular these features are implemented

• dlup.geometry.Polygon: should be mostly compatible with shapely.geometry.Polygon for our use case
• dlup.geometry.Point: a point class, same as above
• dlup.geometry.Box: shapely doesn't support boxes but we do.

The function SlideAnnotations.read_region() returns an AnnotationRegion object rather than list of objects. You can access the polygons using AnnotationRegion.polygons, points using AnnotationRegion.points and boxes using AnnotationRegion.boxes. The first two behave as expected, but the boxes are not cropped to the read_region, so it is possible the (x, y) coordinate is negative (slightly outside of the read_region). In addition there is a call to_mask() that generates the mask. The evaluation is lazy, so a call to read_region does not execute the pipeline until you access the polygons, points, boxes or mask in the object.

The SlideAnnotations has a few new calls:

• set_offset: offsets all the annotations, useful in e.g. Halo annotations
• scale: scales all the annotations in place, useful if you have annotations at lower res and want to rescale to level 0
• as_dlup_xml and from_dlup_xml: this is our own defined schema which is able to serialise SlideAnnotations completely.
• reindex_polygons: this sets an index for the to_mask() in the polygons.
• relabel_polygons: as expected

Lazy evaluation

The library supports lazy evaluation, most operations are only performed when requesting masks or polygons.

WARNING: The operations might not all be thread-safe due to their in-place modification behaviour.

Something that might be nice to have

• Mask support?
• JSON loading in C++? For a typically annotation it is now ±100ms for the current version, 50ms for the C++ version, and likely that can go down to about 10ms if using C++ JSON parsing.

Please add more possible features.

[moerlemans]

To install I had to pip install meson pip install ninja pip install dlup and meson build to get it working. Maybe others can test this in their setup and we can change the readme.md to reflect all of this. I also had to remove the pure=false from the meson.build file (at line 7) because of meson version issues.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 83.61757% with 317 lines in your changes missing coverage. Please review.

Project coverage is 85.73%. Comparing base (8d31221) to head (0009ba5). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
dlup/annotations_experimental.py	67.10%	131 Missing and 71 partials :warning:
dlup/utils/geometry_xml.py	50.49%	41 Missing and 9 partials :warning:
tests/test_slide_annotations.py	90.35%	24 Missing and 6 partials :warning:
dlup/geometry.py	93.95%	9 Missing and 8 partials :warning:
dlup/annotations.py	78.43%	8 Missing and 3 partials :warning:
tests/test_geometry.py	98.34%	6 Missing :warning:
tests/test_annotations.py	87.50%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #252 +/- ## =========================================== - Coverage 98.63% 85.73% -12.90% =========================================== Files 14 45 +31 Lines 1169 4985 +3816 Branches 0 1074 +1074 =========================================== + Hits 1153 4274 +3121 - Misses 16 490 +474 - Partials 0 221 +221 ```

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