Add missing OpenCV 5 geometry APIs; fix stale readNet doc

[shimat]

Summary

• Wraps OpenCV 5 geometry-module functions that were never exposed in OpenCvSharp: ApproxPolyN, MinEnclosingConvexPolygon, GetClosestEllipsePoints (from geometry/2d.hpp), and BuildMST, VoxelGridSampling, RandomSampling, FarthestPointSampling, NormalEstimate (from geometry/segment.hpp and geometry/mst.hpp). Adds the supporting MSTEdge struct and MSTAlgorithm enum.
• Relocates ~64 functions (convexHull, minAreaRect, fitEllipse family, moments, getAffineTransform, etc.) that OpenCV 5 physically moved from imgproc into the new geometry module, from imgproc.h/Cv2_imgproc.cs into geometry.h/Cv2_geometry.cs, renaming the native CVAPI prefix imgproc_ -> geometry_ to match upstream's module layout. The public Cv2 API surface (method names/signatures) is unchanged.
• Fixes Net.ReadNet()'s XML doc, which still described the Caffe/Darknet/Torch model formats; those parsers (and readNetFromCaffe/readNetFromDarknet/readNetFromTorch) were removed in OpenCV 5, and readNet() now only auto-detects TensorFlow/ONNX/OpenVINO formats.

This came out of an audit against the OpenCV 5 wiki page to find gaps in OpenCvSharp's 5.x migration.

Follow-up (not in this PR)

geometry/segment.hpp also declares two larger classes that are still unwrapped: cv::SACSegmentation (RANSAC-based point-cloud plane/sphere segmentation - create() factory plus getters/setters for SacModelType, SacMethod, DistanceThreshold, RadiusLimits, MaxIterations, Confidence, NumberOfModelsExpected, Parallel, RandomGeneratorState, CustomModelConstraints) and cv::RegionGrowing3D (declared further down the same header). These need the CvPtrObject-based algorithm-class pattern (see VolumeSettings/Volume in Modules/ptcloud for a similar recent example), which is a bigger unit of work than the free-function wrapping done here, so it's being picked up in a separate session/PR. A tracked follow-up chip already exists for this.

Test plan

• Native build: cmake --build src/build --config Release --target OpenCvSharpExtern succeeds with no errors.
• Managed build: dotnet build src/OpenCvSharp/OpenCvSharp.csproj -c Release -f net8.0 succeeds, 0 warnings/errors.
• Added unit tests for all 8 newly-wrapped functions in test/OpenCvSharp.Tests/calib3d/GeometryFunctionsTest.cs.
• Full test suite: dotnet test test/OpenCvSharp.Tests/OpenCvSharp.Tests.csproj -c Release - 1252 passed, 0 failed, 27 skipped (pre-existing, environment-dependent).

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features
  • Added new geometry/shape APIs (polygon approximation, convex queries, ellipse/line fitting, bounding primitives, point-in-polygon testing, rotated-rectangle intersections, and affine/perspective transforms).
  • Added point sampling and normal/curvature estimation utilities.
  • Added Minimum Spanning Tree support via BuildMST, including MSTAlgorithm and MSTEdge.
• Breaking Changes
  • Moved geometry helpers from the image-processing API surface to the geometry API surface.
• Documentation
  • Updated DNN model-loading documentation to reflect TensorFlow/ONNX/OpenVINO formats.
• Tests
  • Added coverage for the new geometry and sampling APIs.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: de8baa12-22a1-41b4-9e19-c528bf68a7a5

📥 Commits

Reviewing files that changed from the base of the PR and between 57e390b and c450c7e.

📒 Files selected for processing (1)

• src/OpenCvSharpExtern/geometry.h

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📝 Walkthrough

Walkthrough

This PR adds new geometry APIs and MST support across native wrappers, P/Invoke, and C# surfaces, redirects moments to the new geometry binding, removes the old imgproc geometry surface, and updates tests plus ReadNet documentation.

Changes

Geometry module migration

Layer / File(s)	Summary
MST types and native include setup src/OpenCvSharp/Modules/geometry/Enum/MSTAlgorithm.cs, src/OpenCvSharp/Modules/geometry/MSTEdge.cs, src/OpenCvSharpExtern/my_types.h, src/OpenCvSharpExtern/include_opencv.h	Adds MSTAlgorithm, MSTEdge, interop conversion for MSTEdge, and an explicit opencv2/geometry/mst.hpp include.
Native geometry.h wrapper functions src/OpenCvSharpExtern/geometry.h	Adds CVAPI wrappers for geometry approximation, MST building, sampling, transforms, contour metrics, convex hull/defects, ellipse/line fitting, and intersection operations.
C# NativeMethods geometry P/Invoke declarations src/OpenCvSharp/Internal/PInvoke/NativeMethods/geometry/NativeMethods_geometry.cs	Adds LibraryImport declarations matching the new native geometry wrappers.
Cv2 geometry public API wrappers src/OpenCvSharp/Cv2/Cv2_geometry.cs, src/OpenCvSharp/Modules/imgproc/Moments.cs	Adds public Cv2 geometry wrappers and redirects moments computation to geometry_moments.
Remove legacy imgproc geometry APIs src/OpenCvSharp/Cv2/Cv2_imgproc.cs, src/OpenCvSharp/Internal/PInvoke/NativeMethods/imgproc/NativeMethods_imgproc.cs, src/OpenCvSharpExtern/imgproc.h	Removes the old imgproc geometry wrappers, P/Invoke declarations, and native implementations.
Tests and documentation updates test/OpenCvSharp.Tests/calib3d/GeometryFunctionsTest.cs, src/OpenCvSharp/Modules/dnn/Cv2.Dnn.cs, src/OpenCvSharp/Modules/dnn/Net.cs	Adds tests for the new geometry APIs and updates ReadNet documentation text.

Estimated code review effort: 4 (Complex) | ~60 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Cv2_geometry
  participant NativeMethods_geometry
  participant geometry_h
  participant OpenCV
  Cv2_geometry->>NativeMethods_geometry: call geometry_* P/Invoke
  NativeMethods_geometry->>geometry_h: invoke CVAPI wrapper
  geometry_h->>OpenCV: forward geometry operation
  OpenCV-->>geometry_h: return result
  geometry_h-->>NativeMethods_geometry: fill out parameters
  NativeMethods_geometry-->>Cv2_geometry: return managed result

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly captures the main changes: new OpenCV 5 geometry APIs and updated ReadNet documentation.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feature/opencv5-geometry-module-gaps

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/OpenCvSharp/Cv2/Cv2_geometry.cs`:
- Around line 2650-2654: The BoxPoints wrapper in Cv2_geometry is missing the
usual lifetime guard for the OutputArray argument. Update BoxPoints to keep the
points.Source alive after the NativeMethods.geometry_boxPoints_OutputArray call,
matching the pattern used by the other InputArray/OutputArray wrappers in this
file. Use the existing BoxPoints method and points.Source reference to locate
the fix.
- Around line 2727-2734: `Cv2_geometry.MinEnclosingTriangle` keeps
`points.Source` alive after the native call but does not keep `triangle.Source`
alive, unlike similar methods in this class. Update
`MinEnclosingTriangle(InputArray points, OutputArray triangle)` to add a
`GC.KeepAlive(triangle.Source)` after `NativeMethods.HandleException(...)`,
alongside the existing `GC.KeepAlive(points.Source)`, so the output wrapper
stays rooted for the duration of the interop call.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 9733f167-45c9-4012-95c3-a9c34321beae

📥 Commits

Reviewing files that changed from the base of the PR and between d3bb1f3 and b54bfe7.

📒 Files selected for processing (14)

• src/OpenCvSharp/Cv2/Cv2_geometry.cs
• src/OpenCvSharp/Cv2/Cv2_imgproc.cs
• src/OpenCvSharp/Internal/PInvoke/NativeMethods/geometry/NativeMethods_geometry.cs
• src/OpenCvSharp/Internal/PInvoke/NativeMethods/imgproc/NativeMethods_imgproc.cs
• src/OpenCvSharp/Modules/dnn/Cv2.Dnn.cs
• src/OpenCvSharp/Modules/dnn/Net.cs
• src/OpenCvSharp/Modules/geometry/Enum/MSTAlgorithm.cs
• src/OpenCvSharp/Modules/geometry/MSTEdge.cs
• src/OpenCvSharp/Modules/imgproc/Moments.cs
• src/OpenCvSharpExtern/geometry.h
• src/OpenCvSharpExtern/imgproc.h
• src/OpenCvSharpExtern/include_opencv.h
• src/OpenCvSharpExtern/my_types.h
• test/OpenCvSharp.Tests/calib3d/GeometryFunctionsTest.cs

💤 Files with no reviewable changes (3)

• src/OpenCvSharpExtern/imgproc.h
• src/OpenCvSharp/Internal/PInvoke/NativeMethods/imgproc/NativeMethods_imgproc.cs
• src/OpenCvSharp/Cv2/Cv2_imgproc.cs