Added the is_array2d template.

dlib/array2d/array2d_kernel_1.h

@@ -487,6 +487,14 @@ namespace dlib
         }
     }
 
+// ----------------------------------------------------------------------------------------
+
+    template <typename T, typename MM>
+    struct is_array2d <array2d<T,MM> >  
+    {
+        const static bool value = true;
+    };
+
 // ----------------------------------------------------------------------------------------
 
 }

dlib/is_kind.h

@@ -59,6 +59,19 @@ namespace dlib
         ASSERT_ARE_SAME_TYPE(helper,void);
     };
 
+// ----------------------------------------------------------------------------------------
+
+    template <typename T>
+    struct is_array2d : public default_is_kind_value  
+    {
+        /*!
+            - if (T is an implementation of array2d/array2d_kernel_abstract.h) then
+                - is_array2d<T>::value == true
+            - else
+                - is_array2d<T>::value == false
+        !*/
+    };
+
 // ----------------------------------------------------------------------------------------
 
     template <typename T>

dlib/test/array2d.cpp

@@ -548,6 +548,10 @@ namespace
 
             DLIB_TEST((char*)&img[0][0] + img.width_step() == (char*)&img[1][0]);
         }
+
+        COMPILE_TIME_ASSERT(is_array2d<array2d<unsigned char> >::value == true);
+        COMPILE_TIME_ASSERT(is_array2d<array2d<float> >::value == true);
+        COMPILE_TIME_ASSERT(is_array2d<float>::value == false);
     }