Merge pull request #1877 from shimat/claude/competent-shannon-5acdac

Fix LineSegmentDetector segfault caused by C++/C# calling convention mismatch

Author: shimat

src/OpenCvSharpExtern/imgproc_LineSegmentDetector.h

@@ -38,12 +38,16 @@ CVAPI(cv::Ptr<cv::LineSegmentDetector>*) imgproc_createLineSegmentDetector(
         refine, scale, sigma_scale, quant, ang_th, log_eps, density_th, n_bins));
 }
 
-CVAPI(void) imgproc_Ptr_LineSegmentDetector_delete(cv::Ptr<cv::LineSegmentDetector> *obj)
+CVAPI(ExceptionStatus) imgproc_Ptr_LineSegmentDetector_delete(cv::Ptr<cv::LineSegmentDetector> *obj)
 {
+    BEGIN_WRAP
     delete obj;
+    END_WRAP
 }
 
-CVAPI(cv::LineSegmentDetector*) imgproc_Ptr_LineSegmentDetector_get(cv::Ptr<cv::LineSegmentDetector> *obj)
+CVAPI(ExceptionStatus) imgproc_Ptr_LineSegmentDetector_get(cv::Ptr<cv::LineSegmentDetector> *obj, cv::LineSegmentDetector **returnValue)
 {
-    return obj->get();
+    BEGIN_WRAP
+    *returnValue = obj->get();
+    END_WRAP
 }

test/OpenCvSharp.Tests/imgproc/LineSegmentDetectorTest.cs

@@ -0,0 +1,31 @@
+using Xunit;
+
+namespace OpenCvSharp.Tests.ImgProc;
+
+public class LineSegmentDetectorTest : TestBase
+{
+    [Fact]
+    public void CreateAndDetect()
+    {
+        using var image = new Mat(500, 500, MatType.CV_8UC1, Scalar.All(255));
+        Cv2.Line(image, new Point(50, 50), new Point(450, 50), new Scalar(0, 0, 0), 2);
+
+        using var lsd = LineSegmentDetector.Create();
+        Assert.NotEqual(IntPtr.Zero, lsd.RawPtr);
+
+        lsd.Detect(image, out var lines, out _, out _, out _);
+        Assert.NotEmpty(lines);
+    }
+
+    [Fact]
+    public void DetectOutputArray()
+    {
+        using var image = new Mat(500, 500, MatType.CV_8UC1, Scalar.All(255));
+        Cv2.Line(image, new Point(50, 50), new Point(450, 50), new Scalar(0, 0, 0), 2);
+
+        using var lsd = LineSegmentDetector.Create();
+        using var lines = new Mat();
+        lsd.Detect(image, lines);
+        Assert.False(lines.Empty());
+    }
+}