From 269e89d23f9df92223bbc87a4d8b136c138e1842 Mon Sep 17 00:00:00 2001
From: shimat <schimatk@gmail.com>
Date: Mon, 19 Dec 2022 08:04:12 +0900
Subject: [PATCH] Add MatMemoryManager

---
 .../Fundamentals/MatMemoryManager.cs          | 65 +++++++++++++++++++
 src/OpenCvSharp/Modules/core/Mat/Mat.cs       | 10 ++-
 2 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 src/OpenCvSharp/Fundamentals/MatMemoryManager.cs

diff --git a/src/OpenCvSharp/Fundamentals/MatMemoryManager.cs b/src/OpenCvSharp/Fundamentals/MatMemoryManager.cs
new file mode 100644
index 0000000000..76af982737
--- /dev/null
+++ b/src/OpenCvSharp/Fundamentals/MatMemoryManager.cs
@@ -0,0 +1,65 @@
+using System;
+using System.Buffers;
+
+namespace OpenCvSharp;
+
+/// <summary>
+/// A MemoryManager over an OpenCvSharpMat
+/// </summary>
+/// <remarks>The pointer is assumed to be fully unmanaged, or externally pinned - no attempt will be made to pin this data</remarks>
+public sealed unsafe class MatMemoryManager<T> : MemoryManager<T>
+    where T : unmanaged
+{
+    private readonly Mat wrapped;
+
+    /// <summary>
+    /// Create a new UnmanagedMemoryManager instance at the given pointer and size
+    /// </summary>
+    /// <remarks>It is assumed that the span provided is already unmanaged or externally pinned</remarks>
+    public MatMemoryManager(Mat mat, bool isDataOwner = true)
+    {
+        if (!mat.IsContinuous())
+        {
+            throw new ArgumentException("mat is not continuous", nameof(mat));
+        }
+
+        wrapped = isDataOwner ? mat : new Mat(mat);
+    }
+
+    /// <inheritdoc />
+    public override Span<T> GetSpan() => new((void*)wrapped.Data, (int)wrapped.Total());
+
+    /// <summary>
+    /// Provides access to a pointer that represents the data (note: no actual pin occurs)
+    /// </summary>
+    public override MemoryHandle Pin(int elementIndex = 0)
+    {
+        if (elementIndex < 0 || elementIndex >= wrapped.Total())
+        {
+            throw new ArgumentOutOfRangeException(nameof(elementIndex));
+        }
+
+        var dims = wrapped.Dims;
+        var idxs = new int[dims];
+        var remainIdx = elementIndex;
+        for (var dim = dims - 1; dim >= 0; dim--)
+        {
+            remainIdx = Math.DivRem(remainIdx, wrapped.Size(dim), out idxs[dim]);
+        }
+
+        return new MemoryHandle((void*)wrapped.Ptr(idxs));
+    }
+
+    /// <summary>
+    /// Has no effect
+    /// </summary>
+    public override void Unpin()
+    {
+    }
+
+    /// <summary>
+    /// Releases all resources associated with this object
+    /// </summary>
+    protected override void Dispose(bool disposing) 
+        => wrapped.Dispose();
+}
diff --git a/src/OpenCvSharp/Modules/core/Mat/Mat.cs b/src/OpenCvSharp/Modules/core/Mat/Mat.cs
index 698c56dbf1..dc3ef4e403 100644
--- a/src/OpenCvSharp/Modules/core/Mat/Mat.cs
+++ b/src/OpenCvSharp/Modules/core/Mat/Mat.cs
@@ -3572,7 +3572,7 @@ public bool GetRectangularArray<T>(out T[,] data)
     /// </summary>
     /// <param name="data">Primitive or Vec array to be copied</param>
     /// <returns>Length of copied bytes</returns>
-    public bool SetArray<T>(T[] data)
+    public bool SetArray<T>(params T[] data)
         where T : unmanaged
     {
         CheckArgumentsForConvert<T>(data);
@@ -4107,5 +4107,13 @@ public void ForEachAsVec6d(MatForeachFunctionVec6d operation)
 
     #endregion
 
+    /// <summary>
+    /// Creates a new span over the Mat.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    /// <returns></returns>
+    public unsafe Span<T> AsSpan<T>() where T : unmanaged 
+        => IsContinuous() ? new Span<T>(DataPointer, (int)Total()) : Span<T>.Empty;
+
     #endregion
 }