Merge pull request #9034 from sovrasov:mats_from_initializer_list

Add constructors taking initializer_list for some of OpenCV data types (#9034)

* Add a constructor taking initializer_list for Matx

* Add a constructor taking initializer list for Mat and Mat_

* Add one more method to initialize Mat to the corresponding tutorial

* Add a note how to initialize Matx

* CV_CXX_11->CV_CXX11

doc/tutorials/core/mat_the_basic_image_container/mat_the_basic_image_container.markdown

@@ -192,10 +192,12 @@ object in multiple ways:
 
     ![](images/MatBasicContainerOut3.png)
 
--   For small matrices you may use comma separated initializers:
+-   For small matrices you may use comma separated initializers or initializer lists (C++11 support is required in the last case):
 
     @snippet mat_the_basic_image_container.cpp comma
 
+    @snippet mat_the_basic_image_container.cpp list
+
     ![](images/MatBasicContainerOut6.png)
 
 -   Create a new header for an existing *Mat* object and @ref cv::Mat::clone or @ref cv::Mat::copyTo it.

modules/core/include/opencv2/core/cvdef.h

@@ -357,13 +357,13 @@ Cv64suf;
 /****************************************************************************************\
 *                                    C++ 11                                              *
 \****************************************************************************************/
-#ifndef CV_CXX_11
+#ifndef CV_CXX11
-#  if __cplusplus >= 201103L || defined(_MSC_VER) && _MSC_VER >= 1600
+#  if __cplusplus >= 201103L || (defined(_MSC_VER) && _MSC_VER >= 1600)
-#    define CV_CXX_11 1
+#    define CV_CXX11 1
 #  endif
 #else
-#  if CV_CXX_11 == 0
+#  if CV_CXX11 == 0
-#    undef CV_CXX_11
+#    undef CV_CXX11
 #  endif
 #endif
 
@@ -373,7 +373,7 @@ Cv64suf;
 \****************************************************************************************/
 
 #ifndef CV_CXX_MOVE_SEMANTICS
-#  if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__) || defined(_MSC_VER) && _MSC_VER >= 1600
+#  if __cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__) || (defined(_MSC_VER) && _MSC_VER >= 1600)
 #    define CV_CXX_MOVE_SEMANTICS 1
 #  elif defined(__clang)
 #    if __has_feature(cxx_rvalue_references)

modules/core/include/opencv2/core/mat.hpp

@@ -981,6 +981,12 @@ public:
     */
     template<typename _Tp> explicit Mat(const std::vector<_Tp>& vec, bool copyData=false);
 
+#ifdef CV_CXX11
+    /** @overload
+    */
+    template<typename _Tp> explicit Mat(const std::initializer_list<_Tp> list);
+#endif
+
 #ifdef CV_CXX_STD_ARRAY
     /** @overload
     */
@@ -2170,6 +2176,10 @@ public:
     explicit Mat_(const Point3_<typename DataType<_Tp>::channel_type>& pt, bool copyData=true);
     explicit Mat_(const MatCommaInitializer_<_Tp>& commaInitializer);
 
+#ifdef CV_CXX11
+    Mat_(std::initializer_list<_Tp> values);
+#endif
+
 #ifdef CV_CXX_STD_ARRAY
     template <std::size_t _Nm> explicit Mat_(const std::array<_Tp, _Nm>& arr, bool copyData=false);
 #endif

modules/core/include/opencv2/core/mat.inl.hpp

@@ -570,6 +570,18 @@ Mat::Mat(const std::vector<_Tp>& vec, bool copyData)
         Mat((int)vec.size(), 1, DataType<_Tp>::type, (uchar*)&vec[0]).copyTo(*this);
 }
 
+#ifdef CV_CXX11
+template<typename _Tp> inline
+Mat::Mat(const std::initializer_list<_Tp> list)
+    : flags(MAGIC_VAL | DataType<_Tp>::type | CV_MAT_CONT_FLAG), dims(2), rows((int)list.size()),
+      cols(1), data(0), datastart(0), dataend(0), datalimit(0), allocator(0), u(0), size(&rows), step(0)
+{
+    if(list.size() == 0)
+        return;
+    Mat((int)list.size(), 1, DataType<_Tp>::type, (uchar*)list.begin()).copyTo(*this);
+}
+#endif
+
 #ifdef CV_CXX_STD_ARRAY
 template<typename _Tp, std::size_t _Nm> inline
 Mat::Mat(const std::array<_Tp, _Nm>& arr, bool copyData)
@@ -1573,6 +1585,13 @@ Mat_<_Tp>::Mat_(const std::vector<_Tp>& vec, bool copyData)
     : Mat(vec, copyData)
 {}
 
+#ifdef CV_CXX11
+template<typename _Tp> inline
+Mat_<_Tp>::Mat_(std::initializer_list<_Tp> list)
+    : Mat(list)
+{}
+#endif
+
 #ifdef CV_CXX_STD_ARRAY
 template<typename _Tp> template<std::size_t _Nm> inline
 Mat_<_Tp>::Mat_(const std::array<_Tp, _Nm>& arr, bool copyData)

modules/core/include/opencv2/core/matx.hpp

@@ -53,6 +53,10 @@
 #include "opencv2/core/traits.hpp"
 #include "opencv2/core/saturate.hpp"
 
+#ifdef CV_CXX11
+#include <initializer_list>
+#endif
+
 namespace cv
 {
 
@@ -77,12 +81,21 @@ If you need a more flexible type, use Mat . The elements of the matrix M are acc
 M(i,j) notation. Most of the common matrix operations (see also @ref MatrixExpressions ) are
 available. To do an operation on Matx that is not implemented, you can easily convert the matrix to
 Mat and backwards:
-@code
+@code{.cpp}
     Matx33f m(1, 2, 3,
               4, 5, 6,
               7, 8, 9);
     cout << sum(Mat(m*m.t())) << endl;
- @endcode
+@endcode
+Except of the plain constructor which takes a list of elements, Matx can be initialized from a C-array:
+@code{.cpp}
+    float values[] = { 1, 2, 3};
+    Matx31f m(values);
+@endcode
+In case if C++11 features are avaliable, std::initializer_list can be also used to initizlize Matx:
+@code{.cpp}
+    Matx31f m = { 1, 2, 3};
+@endcode
  */
 template<typename _Tp, int m, int n> class Matx
 {
@@ -125,6 +138,10 @@ public:
          _Tp v12, _Tp v13, _Tp v14, _Tp v15); //!< 1x16, 4x4 or 16x1 matrix
     explicit Matx(const _Tp* vals); //!< initialize from a plain array
 
+#ifdef CV_CXX11
+    Matx(std::initializer_list<_Tp>); //!< initialize from an initializer list
+#endif
+
     static Matx all(_Tp alpha);
     static Matx zeros();
     static Matx ones();
@@ -327,6 +344,10 @@ public:
     Vec(_Tp v0, _Tp v1, _Tp v2, _Tp v3, _Tp v4, _Tp v5, _Tp v6, _Tp v7, _Tp v8, _Tp v9, _Tp v10, _Tp v11, _Tp v12, _Tp v13); //!< 14-element vector constructor
     explicit Vec(const _Tp* values);
 
+#ifdef CV_CXX11
+    Vec(std::initializer_list<_Tp>);
+#endif
+
     Vec(const Vec<_Tp, cn>& v);
 
     static Vec all(_Tp alpha);
@@ -616,6 +637,19 @@ Matx<_Tp, m, n>::Matx(const _Tp* values)
     for( int i = 0; i < channels; i++ ) val[i] = values[i];
 }
 
+#ifdef CV_CXX11
+template<typename _Tp, int m, int n> inline
+Matx<_Tp, m, n>::Matx(std::initializer_list<_Tp> list)
+{
+    CV_DbgAssert(list.size() == channels);
+    int i = 0;
+    for(const auto& elem : list)
+    {
+        val[i++] = elem;
+    }
+}
+#endif
+
 template<typename _Tp, int m, int n> inline
 Matx<_Tp, m, n> Matx<_Tp, m, n>::all(_Tp alpha)
 {
@@ -957,6 +991,12 @@ template<typename _Tp, int cn> inline
 Vec<_Tp, cn>::Vec(const _Tp* values)
     : Matx<_Tp, cn, 1>(values) {}
 
+#ifdef CV_CXX11
+template<typename _Tp, int cn> inline
+Vec<_Tp, cn>::Vec(std::initializer_list<_Tp> list)
+    : Matx<_Tp, cn, 1>(list) {}
+#endif
+
 template<typename _Tp, int cn> inline
 Vec<_Tp, cn>::Vec(const Vec<_Tp, cn>& m)
     : Matx<_Tp, cn, 1>(m.val) {}
@@ -1081,7 +1121,7 @@ Vec<_Tp, cn> normalize(const Vec<_Tp, cn>& v)
 
 
 
-//////////////////////////////// matx comma initializer //////////////////////////////////
+//////////////////////////////// vec comma initializer //////////////////////////////////
 
 
 template<typename _Tp, typename _T2, int cn> static inline

modules/core/include/opencv2/core/utility.hpp

@@ -56,7 +56,7 @@
 #include "opencv2/core.hpp"
 #include <ostream>
 
-#ifdef CV_CXX_11
+#ifdef CV_CXX11
 #include <functional>
 #endif
 
@@ -482,7 +482,7 @@ public:
 */
 CV_EXPORTS void parallel_for_(const Range& range, const ParallelLoopBody& body, double nstripes=-1.);
 
-#ifdef CV_CXX_11
+#ifdef CV_CXX11
 class ParallelLoopBodyLambdaWrapper : public ParallelLoopBody
 {
 private:

modules/core/test/test_mat.cpp

@@ -1398,6 +1398,15 @@ TEST(Core_Matx, fromMat_)
     ASSERT_EQ( cvtest::norm(a, b, NORM_INF), 0.);
 }
 
+#ifdef CV_CXX11
+TEST(Core_Matx, from_initializer_list)
+{
+    Mat_<double> a = (Mat_<double>(2,2) << 10, 11, 12, 13);
+    Matx22d b = {10, 11, 12, 13};
+    ASSERT_EQ( cvtest::norm(a, b, NORM_INF), 0.);
+}
+#endif
+
 TEST(Core_InputArray, empty)
 {
     vector<vector<Point> > data;
@@ -1735,7 +1744,7 @@ TEST(Mat, regression_8680)
    ASSERT_EQ(mat.channels(), 2);
 }
 
-#ifdef CV_CXX_11
+#ifdef CV_CXX11
 
 TEST(Mat_, range_based_for)
 {
@@ -1751,4 +1760,21 @@ TEST(Mat_, range_based_for)
     ASSERT_DOUBLE_EQ(norm(img, ref), 0.);
 }
 
+TEST(Mat, from_initializer_list)
+{
+    Mat A({1.f, 2.f, 3.f});
+    Mat_<float> B(3, 1); B << 1, 2, 3;
+
+    ASSERT_EQ(A.type(), CV_32F);
+    ASSERT_DOUBLE_EQ(norm(A, B, NORM_INF), 0.);
+}
+
+TEST(Mat_, from_initializer_list)
+{
+    Mat_<float> A = {1, 2, 3};
+    Mat_<float> B(3, 1); B << 1, 2, 3;
+
+    ASSERT_DOUBLE_EQ(norm(A, B, NORM_INF), 0.);
+}
+
 #endif

samples/cpp/tutorial_code/core/how_to_use_OpenCV_parallel_for_/how_to_use_OpenCV_parallel_for_.cpp

@@ -102,7 +102,7 @@ int main()
 
     double t1 = (double) getTickCount();
 
-    #ifdef CV_CXX_11
+    #ifdef CV_CXX11
 
     //! [mandelbrot-parallel-call-cxx11]
     parallel_for_(Range(0, mandelbrotImg.rows*mandelbrotImg.cols), [&](const Range& range){

samples/cpp/tutorial_code/core/mat_the_basic_image_container/mat_the_basic_image_container.cpp

@@ -58,7 +58,13 @@ int main(int,char**)
     Mat C = (Mat_<double>(3,3) << 0, -1, 0, -1, 5, -1, 0, -1, 0);
     cout << "C = " << endl << " " << C << endl << endl;
     //! [comma]
-
+    // do the same with initializer_list
+#ifdef CV_CXX11
+    //! [list]
+    C = (Mat_<double>({0, -1, 0, -1, 5, -1, 0, -1, 0})).reshape(3);
+    cout << "C = " << endl << " " << C << endl << endl;
+    //! [list]
+#endif
     //! [clone]
     Mat RowClone = C.row(1).clone();
     cout << "RowClone = " << endl << " " << RowClone << endl << endl;