Added transparent conversions for cv::Vec

python/pybind11_opencv.hpp

+/*
+    python/pybind11_opencv.hpp: Transparent conversion for OpenCV cv::Mat matrices.
+                                This header is based on pybind11/eigen.h.
+
+    Copyright (c) 2016 Patrik Huber
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in pybind11's LICENSE file.
+*/
+#pragma once
+
+#include "pybind11/numpy.h"
+
+#include "opencv2/core/core.hpp"
+
+#include <iostream>
+
+NAMESPACE_BEGIN(pybind11)
+NAMESPACE_BEGIN(detail)
+
+/**
+ * @file python/pybind11_opencv.hpp
+ * @brief Transparent conversion to and from Python for OpenCV vectors.
+ */
+
+template<typename T, int N>
+struct type_caster<cv::Vec<T, N>>
+{
+	using vector_type = cv::Vec<T, N>;
+	using Scalar = T;
+	static constexpr std::size_t num_elements = N;
+
+	bool load(handle src, bool)
+	{
+		array_t<Scalar> buf(src, true);
+		if (!buf)
+			return false;
+
+		if (buf.ndim() == 1) // a 1-dimensional vector
+		{
+			if (buf.shape(0) != num_elements) {
+				return false; // not a N-elements vector (can this ever happen?)
+			}
+			if (buf.strides(0) != sizeof(Scalar))
+			{
+				std::cout << "An array with non-standard strides is given. Please pass a contiguous array." << std::endl;
+				return false;
+			}
+			value = cv::Vec<T, N>(buf.mutable_data());
+		}
+		else { // buf.ndim() != 1
+			return false;
+		}
+		return true;
+	}
+
+	static handle cast(const vector_type& src, return_value_policy /* policy */, handle /* parent */)
+	{
+		return array(
+			num_elements,	// shape
+			src.val			// data
+		).release();
+	}
+
+	// Specifies the doc-string for the type in Python:
+	PYBIND11_TYPE_CASTER(vector_type, _("numpy.ndarray[") + npy_format_descriptor<Scalar>::name() +
+		_("[") + _<num_elements>() + _("]]"));
+};
+
+NAMESPACE_END(detail)
+NAMESPACE_END(pybind11)