OpenCV 5 native port: OpenCvSharpExtern compiles against OpenCV 5.0.0

.github/workflows/docker-test-ubuntu.yml

@@ -9,9 +9,9 @@ on:
 
 env:
   DEBIAN_FRONTEND: noninteractive
-  OPENCV_VERSION: 4.13.0
-  DOCKER_BUILD_CONTEXT_FULL: ./docker/ubuntu24-dotnet10-opencv4.13.0
-  DOCKER_BUILD_CONTEXT_SLIM: ./docker/ubuntu24-dotnet10-opencv4.13.0-slim
+  OPENCV_VERSION: 5.0.0
+  DOCKER_BUILD_CONTEXT_FULL: ./docker/ubuntu24-dotnet10-opencv5.0.0
+  DOCKER_BUILD_CONTEXT_SLIM: ./docker/ubuntu24-dotnet10-opencv5.0.0-slim
 
 jobs:
   build_full:
@@ -21,16 +21,16 @@ jobs:
     steps:
       - uses: actions/checkout@v6
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v4
 
       - name: Build with Docker (full)
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@v7
         with:
           context: .
           file: ${{ env.DOCKER_BUILD_CONTEXT_FULL }}/Dockerfile
           build-args: |
             OPENCV_VERSION=${{ env.OPENCV_VERSION }}
-          outputs: type=docker,name=shimat/ubuntu24-dotnet10-opencv4.13.0:latest
+          outputs: type=docker,name=shimat/ubuntu24-dotnet10-opencv5.0.0:latest
           cache-from: |
             type=gha,scope=full-${{ github.ref_name }}
             type=gha,scope=full-main
@@ -43,16 +43,16 @@ jobs:
     steps:
       - uses: actions/checkout@v6
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v4
 
       - name: Build with Docker (slim)
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@v7
         with:
           context: .
           file: ${{ env.DOCKER_BUILD_CONTEXT_SLIM }}/Dockerfile
           build-args: |
             OPENCV_VERSION=${{ env.OPENCV_VERSION }}
-          outputs: type=docker,name=shimat/ubuntu24-dotnet10-opencv4.13.0-slim:latest
+          outputs: type=docker,name=shimat/ubuntu24-dotnet10-opencv5.0.0-slim:latest
           cache-from: |
             type=gha,scope=slim-${{ github.ref_name }}
             type=gha,scope=slim-main

.github/workflows/linux-arm64.yml

@@ -62,13 +62,21 @@ jobs:
       - name: Configure OpenCV
         if: steps.opencv-cache.outputs.cache-hit != 'true'
         run: |
+          # Disable the generic ASM language so OpenCV 5's vendored MLAS skips its
+          # ASM kernels and reports MLAS unavailable (DNN falls back to its
+          # built-in SGEMM). On aarch64 the MLAS FP16/GQA path references
+          # MlasHGemmSupported(), which OpenCV 5.0.0 declares and calls but never
+          # defines, breaking the extern link with an undefined reference.
+          # GCC 12+ builds libjpeg-turbo/libpng SIMD via NEON intrinsics (not GAS),
+          # so dropping the ASM compiler does not affect the image codecs here.
           cmake \
             -G Ninja \
             -C cmake/opencv_build_options.cmake \
             -S opencv \
             -B opencv/build \
             -D OPENCV_EXTRA_MODULES_PATH=${GITHUB_WORKSPACE}/opencv_contrib/modules \
             -D CMAKE_INSTALL_PREFIX=${GITHUB_WORKSPACE}/opencv_artifacts \
+            -D CMAKE_ASM_COMPILER="" \
             2>&1 | tee /tmp/opencv-configure.log
 
       - name: Verify OpenCV cmake features

.github/workflows/manylinux.yml

@@ -266,12 +266,13 @@ jobs:
             -S src \
             -B src/build-slim \
             -D CMAKE_BUILD_TYPE=Release \
-            -D OpenCV_DIR=${GITHUB_WORKSPACE}/opencv_artifacts_slim/lib64/cmake/opencv4 \
+            -D OpenCV_DIR=${GITHUB_WORKSPACE}/opencv_artifacts_slim/lib64/cmake/opencv5 \
             -D CMAKE_PREFIX_PATH=${GITHUB_WORKSPACE}/opencv_artifacts_slim \
             -D NO_CONTRIB=ON \
             -D NO_VIDEOIO=ON \
             -D NO_HIGHGUI=ON \
-            -D NO_DNN=ON
+            -D NO_DNN=ON \
+            -D NO_STITCHING=ON
           cmake --build src/build-slim -j
           cp src/build-slim/OpenCvSharpExtern/libOpenCvSharpExtern.so ${GITHUB_WORKSPACE}/libOpenCvSharpExtern-slim.so
 

.github/workflows/wasm.yml

@@ -110,7 +110,7 @@ jobs:
             -DBUILD_opencv_objc_bindings_generator=OFF \
             -DBUILD_opencv_rapid=OFF \
             -DBUILD_opencv_reg=OFF \
-            -DBUILD_opencv_stereo=OFF \
+            -DBUILD_opencv_stereo=ON \
             -DBUILD_opencv_structured_light=OFF \
             -DBUILD_opencv_surface_matching=OFF \
             -DBUILD_opencv_wechat_qrcode=ON \
@@ -133,7 +133,7 @@ jobs:
           cmake --install opencv-${OPENCV_VERSION}/build
           em++ -r -o ${GITHUB_WORKSPACE}/opencv_wasm/libopencv.o \
             -Wl,--whole-archive ${GITHUB_WORKSPACE}/opencv_wasm/lib/*.a \
-            ${GITHUB_WORKSPACE}/opencv_wasm/lib/opencv4/3rdparty/*.a
+            ${GITHUB_WORKSPACE}/opencv_wasm/lib/opencv5/3rdparty/*.a
           ls
 
       - name: Save OpenCV cache
@@ -150,7 +150,7 @@ jobs:
         run: |
           ls ${GITHUB_WORKSPACE}/opencv_wasm
           echo "-----"
-          emcmake cmake -S src -B src/build -DCMAKE_BUILD_TYPE=Release -DOpenCV_DIR=${GITHUB_WORKSPACE}/opencv_wasm/lib/cmake/opencv4 -DWASM_LIB=${GITHUB_WORKSPACE}/opencv_wasm/libopencv.o
+          emcmake cmake -S src -B src/build -DCMAKE_BUILD_TYPE=Release -DOpenCV_DIR=${GITHUB_WORKSPACE}/opencv_wasm/lib/cmake/opencv5 -DWASM_LIB=${GITHUB_WORKSPACE}/opencv_wasm/libopencv.o
           cmake --build src/build --parallel $(nproc)
           ls src/build/OpenCvSharpExtern
           cp src/build/OpenCvSharpExtern/libOpenCvSharpExtern.a ${GITHUB_WORKSPACE}/nuget/

.github/workflows/windows.yml

@@ -71,6 +71,14 @@ jobs:
         shell: powershell
         run: |
           $ErrorActionPreference = 'Continue'
+          # Force OpenCV 5's vendored MLAS off by giving CMake no ASM compiler
+          # (see -D CMAKE_ASM_COMPILER below). MinGW or Strawberry-Perl gcc on the
+          # runner PATH would otherwise be picked by MLAS's check_language(ASM),
+          # building GNU-syntax .S SGEMM kernels that fail the MSVC link (x64:
+          # missing SgemmKernelSse2.obj) and inject pthread into the OpenCV link
+          # interface (arm64: LNK1181 pthread.lib). MLAS then disables and DNN uses
+          # its built-in SGEMM, matching a clean local VS build. Windows builds the
+          # image codecs via vcpkg, so no other ASM language is needed.
           cmake `
             -C cmake/opencv_build_options.cmake `
             -S opencv `
@@ -83,6 +91,7 @@ jobs:
             -D "VCPKG_OVERLAY_TRIPLETS=$env:GITHUB_WORKSPACE/cmake/triplets" `
             -D OPENCV_EXTRA_MODULES_PATH="$env:GITHUB_WORKSPACE/opencv_contrib/modules" `
             -D CMAKE_INSTALL_PREFIX="$env:GITHUB_WORKSPACE/opencv_artifacts" `
+            -D CMAKE_ASM_COMPILER="" `
             *>&1 | Tee-Object -FilePath "$env:TEMP\opencv-configure.log"
           if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
 
@@ -160,6 +169,7 @@ jobs:
             -D NO_VIDEOIO=ON `
             -D NO_HIGHGUI=ON `
             -D NO_DNN=ON `
+            -D NO_STITCHING=ON `
             -D NO_INSTALL_TO_TEST=ON
           cmake --build src/build_slim --config Release -j 4
 
@@ -302,6 +312,25 @@ jobs:
         shell: powershell
         run: |
           $ErrorActionPreference = 'Continue'
+          # Force OpenCV 5's vendored MLAS off by giving CMake no ASM compiler
+          # (see -D CMAKE_ASM_COMPILER below). MinGW or Strawberry-Perl gcc on the
+          # runner PATH would otherwise be picked by MLAS's check_language(ASM),
+          # building GNU-syntax .S SGEMM kernels that fail the MSVC link (x64:
+          # missing SgemmKernelSse2.obj) and inject pthread into the OpenCV link
+          # interface (arm64: LNK1181 pthread.lib). MLAS then disables and DNN uses
+          # its built-in SGEMM, matching a clean local VS build. Windows builds the
+          # image codecs via vcpkg, so no other ASM language is needed.
+          # OpenCV 5's vendored MLAS uses GNU-syntax aarch64 .S SGEMM kernels that
+          # armasm64 (the only ASM compiler on the VS2022 ARM64 toolchain, which
+          # windows-11-arm ships instead of VS2026) cannot assemble, and
+          # CMAKE_ASM_COMPILER="" does not disable ASM under the VS ARM64 generator
+          # (it does under VS2026 x64). MLAS is an OpenCV 5 addition (absent in
+          # OpenCV 4), so skip building it on this toolchain; DNN keeps working via
+          # its built-in SGEMM (as OpenCV 4 ARM64 did). Drop the add_subdirectory
+          # that pulls MLAS into opencv_dnn.
+          (Get-Content opencv/modules/dnn/CMakeLists.txt) `
+            -replace 'add_subdirectory\("\$\{OpenCV_SOURCE_DIR\}/3rdparty/mlas".*', '# [win-arm64] MLAS disabled (armasm64 cannot assemble its aarch64 .S kernels)' `
+            | Set-Content opencv/modules/dnn/CMakeLists.txt
           cmake `
             -C cmake/opencv_build_options.cmake `
             -S opencv `
@@ -315,6 +344,7 @@ jobs:
             -D OPENCV_EXTRA_MODULES_PATH="$env:GITHUB_WORKSPACE/opencv_contrib/modules" `
             -D CMAKE_INSTALL_PREFIX="$env:GITHUB_WORKSPACE/opencv_artifacts" `
             -D WITH_FFMPEG=OFF `
+            -D CMAKE_ASM_COMPILER="" `
             *>&1 | Tee-Object -FilePath "$env:TEMP\opencv-configure.log"
           if ($LASTEXITCODE -ne 0) { exit $LASTEXITCODE }
 
@@ -385,6 +415,7 @@ jobs:
             -D NO_VIDEOIO=ON `
             -D NO_HIGHGUI=ON `
             -D NO_DNN=ON `
+            -D NO_STITCHING=ON `
             -D NO_INSTALL_TO_TEST=ON
           cmake --build src/build_arm64_slim --config Release -j 4
 

build_opencv_windows.ps1

@@ -118,6 +118,7 @@ if (Test-Path $cmakeCache) {
     Write-Host "Removing stale CMakeCache.txt ..."
     Remove-Item $cmakeCache -Force
 }
+
 cmake `
     -C "$RepoRoot/cmake/opencv_build_options.cmake" `
     -S "$RepoRoot/opencv" `
@@ -126,6 +127,7 @@ cmake `
     -D "CMAKE_GENERATOR_INSTANCE=$vsInstallPath" `
     -D "CMAKE_TOOLCHAIN_FILE=$vcpkgToolchain" `
     -D "VCPKG_TARGET_TRIPLET=x64-windows-static" `
+    -D "VCPKG_MANIFEST_DIR=$RepoRoot" `
     -D "VCPKG_INSTALLED_DIR=$vcpkgInstalledDir" `
     -D "VCPKG_OVERLAY_TRIPLETS=$RepoRoot/cmake/triplets" `
     -D "OPENCV_EXTRA_MODULES_PATH=$RepoRoot/opencv_contrib/modules" `

cmake/opencv_build_options.cmake

@@ -35,7 +35,9 @@ set(BUILD_opencv_mcc                       OFF CACHE BOOL "" FORCE)
 set(BUILD_opencv_objc_bindings_generator   OFF CACHE BOOL "" FORCE)
 set(BUILD_opencv_rapid                     OFF CACHE BOOL "" FORCE)
 set(BUILD_opencv_reg                       OFF CACHE BOOL "" FORCE)
-set(BUILD_opencv_stereo                    OFF CACHE BOOL "" FORCE)
+# OpenCV 5: calib3d was split and StereoMatcher/StereoBM/StereoSGBM now live in
+# the main "stereo" module, so it must be built (ximgproc/disparity_filter needs it).
+set(BUILD_opencv_stereo                    ON  CACHE BOOL "" FORCE)
 set(BUILD_opencv_structured_light          OFF CACHE BOOL "" FORCE)
 set(BUILD_opencv_surface_matching          OFF CACHE BOOL "" FORCE)
 set(BUILD_opencv_videostab                 OFF CACHE BOOL "" FORCE)

cmake/opencv_build_options_slim.cmake

@@ -6,8 +6,25 @@ set(CMAKE_BUILD_TYPE  Release CACHE STRING "" FORCE)
 set(BUILD_SHARED_LIBS OFF     CACHE BOOL   "" FORCE)
 set(ENABLE_CXX11      ON      CACHE BOOL   "" FORCE)
 
-# Restrict to a minimal module subset
-set(BUILD_LIST "core,imgproc,imgcodecs,calib3d,features2d,flann,objdetect,photo,ml,video,stitching,barcode" CACHE STRING "" FORCE)
+# Restrict to a minimal module subset.
+# OpenCV 5 module renames vs 4.x:
+#   - calib3d was split into geometry (2D/3D primitives: convexHull, solvePnP,
+#     findHomography, ...), calib (camera calibration) and stereo (StereoBM/SGBM)
+#   - features2d was renamed to features
+#   - barcode was merged into objdetect (no standalone module anymore)
+#   - CascadeClassifier / HOGDescriptor / groupRectangles moved to the contrib
+#     xobjdetect module (lightweight: depends only on core/imgproc/imgcodecs/
+#     features), kept in the slim profile. Pulled from OPENCV_EXTRA_MODULES_PATH.
+#   - BRISK / KAZE / AKAZE / AGAST / FREAK / BRIEF / DAISY / ... moved to the
+#     contrib xfeatures2d module. Its required deps (core/imgproc/features/
+#     geometry) are all in this list and it pulls no heavy external dependency,
+#     so it is kept in the slim profile too.
+# Additional lightweight contrib kept in slim (deps all in this list, no heavy
+# external dependency): ximgproc, xphoto, bgsegm, img_hash.
+# stitching is dropped from slim (large, niche); the extern is built with
+# NO_STITCHING=ON to match.
+# Dependencies of whitelisted modules are added automatically.
+set(BUILD_LIST "core,imgproc,imgcodecs,geometry,calib,stereo,features,flann,objdetect,photo,ml,video,xobjdetect,xfeatures2d,ximgproc,xphoto,bgsegm,img_hash" CACHE STRING "" FORCE)
 
 # Disable DNN and Protobuf (not needed in slim profile)
 set(BUILD_opencv_dnn  OFF CACHE BOOL "" FORCE)

docker/ubuntu24-dotnet10-opencv5.0.0-slim/Dockerfile

@@ -79,7 +79,8 @@ RUN --mount=type=cache,target=/root/.ccache \
       -D NO_CONTRIB=ON \
       -D NO_VIDEOIO=ON \
       -D NO_HIGHGUI=ON \
-      -D NO_DNN=ON; \
+      -D NO_DNN=ON \
+      -D NO_STITCHING=ON; \
     cmake --build /opencvsharp/make --parallel "$(nproc)"; \
     cmake --install /opencvsharp/make; \
     rm -rf /opencv /opencv_contrib; \

docs/migration-4-to-5.md

@@ -44,9 +44,27 @@ working — but you no longer need a separate extensions package for it.
 
 ## 3. Removed APIs
 
-| Removed | Replacement |
+These wrap OpenCV functions that were removed in OpenCV 5 (no replacement), so
+the managed methods are gone too:
+
+| Removed | Notes / replacement |
+|---|---|
+| `OpenCvSharp.Extensions.Binarizer` (Niblack/Sauvola/Bernsen/Nick/…) | Use `CvXImgProc.NiblackThreshold` (Niblack / Sauvola / Wolf / Nick) |
+| `CvDnn.ReadNetFromDarknet`, `CvDnn.ReadNetFromCaffe`, `CvDnn.ReadNetFromTorch`, `CvDnn.ReadTorchBlob`, `CvDnn.ShrinkCaffeModel` (and the `Net.*` equivalents) | Darknet/Caffe/Torch parsers removed — export to ONNX and use `CvDnn.ReadNetFromONNX` |
+| `Net.SetHalideScheduler` | Halide backend removed |
+| `Cv2.ConvertFp16` | Use `Mat.ConvertTo` to/from `MatType.CV_16F` |
+| `Cv2.LogPolar`, `Cv2.LinearPolar` | Use `Cv2.WarpPolar` (`WarpPolarMode.Linear` / `Log`) |
+| `Window.GetHandle()`, `Cv2.GetWindowHandle` | Legacy C API removed; no replacement |
+| `TrackerGOTURN` | Removed from OpenCV 5 |
+
+## 3a. Changed signatures
+
+Caffe model support was dropped; these constructors now take ONNX model paths:
+
+| Before (OpenCvSharp4) | After (OpenCvSharp5) |
 |---|---|
-| `OpenCvSharp.Extensions.Binarizer` (Niblack/Sauvola/Bernsen/Nick/…) | OpenCV `ximgproc` niBlack threshold — `CvXImgProc.NiblackThreshold` (supports Niblack / Sauvola / Wolf / Nick) |
+| `new BarcodeDetector(superResolutionPrototxtPath, superResolutionCaffeModelPath)` | `new BarcodeDetector(superResolutionModelPath = "")` |
+| `new WeChatQRCode(detectorPrototxt, detectorCaffe, srPrototxt, srCaffe)` | `new WeChatQRCode(detectorModelPath = "", superResolutionModelPath = "")` |
 
 ## 4. OpenCV 5 API changes surfaced through the wrapper
 

src/OpenCvSharp/Cv2/Cv2_core.cs

@@ -337,32 +337,6 @@ public static void ConvertScaleAbs(InputArray src, OutputArray dst, double alpha
         dst.Fix();
     }
 
-    /// <summary>
-    /// Converts an array to half precision floating number.
-    ///
-    /// This function converts FP32(single precision floating point) from/to FP16(half precision floating point). CV_16S format is used to represent FP16 data.
-    /// There are two use modes(src -&gt; dst) : CV_32F -&gt; CV_16S and CV_16S -&gt; CV_32F.The input array has to have type of CV_32F or
-    /// CV_16S to represent the bit depth.If the input array is neither of them, the function will raise an error.
-    /// The format of half precision floating point is defined in IEEE 754-2008.
-    /// </summary>
-    /// <param name="src">input array.</param>
-    /// <param name="dst">output array.</param>
-    public static void ConvertFp16(InputArray src, OutputArray dst)
-    {
-        if (src is null)
-            throw new ArgumentNullException(nameof(src));
-        if (dst is null)
-            throw new ArgumentNullException(nameof(dst));
-        src.ThrowIfDisposed();
-        dst.ThrowIfNotReady();
-
-        NativeMethods.HandleException(
-            NativeMethods.core_convertFp16(src.CvPtr, dst.CvPtr));
-
-        GC.KeepAlive(src);
-        dst.Fix();
-    }
-
     /// <summary>
     /// transforms array of numbers using a lookup table: dst(i)=lut(src(i))
     /// </summary>

src/OpenCvSharp/Cv2/Cv2_highgui.cs

@@ -443,18 +443,4 @@ public static void SetTrackbarMin(string trackbarName, string winName, int minVa
         NativeMethods.HandleException(
             NativeMethods.highgui_setTrackbarMin(trackbarName, winName, minVal));
     }
-
-    /// <summary>
-    /// get native window handle (HWND in case of Win32 and Widget in case of X Window) 
-    /// </summary>
-    /// <param name="windowName"></param>
-    public static IntPtr GetWindowHandle(string windowName)
-    {
-        if (windowName is null)
-            throw new ArgumentNullException(nameof(windowName));
-
-        NativeMethods.HandleException(
-            NativeMethods.highgui_cvGetWindowHandle(windowName, out var ret));
-        return ret;
-    }
 }