imgcodecs: refactoring, improve code quality

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

@@ -3248,6 +3248,9 @@ public:
     //! returns read-only pointer to the real buffer, stack-allocated or head-allocated
     operator const _Tp* () const;
 
+    //! returns number of allocated elements
+    size_t getSize() const;
+
 protected:
     //! pointer to the real buffer, can point to buf if the buffer is small enough
     _Tp* ptr;

modules/core/include/opencv2/core/operations.hpp

@@ -2581,6 +2581,9 @@ template<typename _Tp, size_t fixed_size> inline AutoBuffer<_Tp, fixed_size>::op
 template<typename _Tp, size_t fixed_size> inline AutoBuffer<_Tp, fixed_size>::operator const _Tp* () const
 { return ptr; }
 
+template<typename _Tp, size_t fixed_size> inline size_t AutoBuffer<_Tp, fixed_size>::getSize() const
+{ return size; }
+
 
 /////////////////////////////////// Ptr ////////////////////////////////////////