add nr and nc methods to jpeg, png and webp loaders (#2920)

* add nr and nc methods to jpeg, png and webp loaders

* Oops, forgot to declare methods in jpeg_loader.h

dlib/image_loader/jpeg_loader.cpp

@@ -75,6 +75,21 @@ namespace dlib
         return (output_components_ == 4);
     }
 
+
+// ----------------------------------------------------------------------------------------
+
+    long jpeg_loader::nr() const
+    {
+        return static_cast<long>(height_);
+    }
+
+// ----------------------------------------------------------------------------------------
+
+    long jpeg_loader::nc() const
+    {
+        return static_cast<long>(width_);
+    }
+
 // ----------------------------------------------------------------------------------------
 
     struct jpeg_loader_error_mgr 

dlib/image_loader/jpeg_loader.h

@@ -26,6 +26,8 @@ namespace dlib
         bool is_gray() const;
         bool is_rgb() const;
         bool is_rgba() const;
+        long nr() const;
+        long nc() const;
 
         template<typename T>
         void get_image( T& t_) const

dlib/image_loader/jpeg_loader_abstract.h

@@ -105,6 +105,22 @@ namespace dlib
                     - returns false
         !*/
 
+        long nr (
+        ) const;
+        /*!
+            ensures
+                - returns the number of rows (height) of the image contained by this
+                  object.
+        !*/
+
+        long nc (
+        ) const;
+        /*!
+            ensures
+                - returns the number of colums (width) of the image contained by this
+                  object.
+        !*/
+
         template<
             typename image_type 
             >

dlib/image_loader/png_loader.cpp

@@ -156,6 +156,8 @@ namespace dlib
     bool png_loader::is_rgb()   const { return color_type == PNG_COLOR_TYPE_RGB; }
     bool png_loader::is_rgba()  const { return color_type == PNG_COLOR_TYPE_RGB_ALPHA; }
     unsigned int png_loader::bit_depth () const {return bit_depth_;}  
+    long png_loader::nr() const { return height; }
+    long png_loader::nc() const { return width; }
 
 // ----------------------------------------------------------------------------------------
 

dlib/image_loader/png_loader.h

@@ -36,6 +36,8 @@ namespace dlib
         bool is_rgb()               const;
         bool is_rgba()              const;
         unsigned int bit_depth ()   const;
+        long nr()                   const;
+        long nc()                   const;
 
         template<class image_type>
         void get_image( image_type& img) const 

dlib/image_loader/png_loader_abstract.h

@@ -145,6 +145,22 @@ namespace dlib
                   object.  The possible values are 8 or 16.
         !*/
 
+        long nr (
+        ) const;
+        /*!
+            ensures
+                - returns the number of rows (height) of the image contained by this
+                  object.
+        !*/
+
+        long nc (
+        ) const;
+        /*!
+            ensures
+                - returns the number of colums (width) of the image contained by this
+                  object.
+        !*/
+
         template<
             typename image_type 
             >

dlib/image_loader/webp_loader.cpp

@@ -62,6 +62,11 @@ namespace dlib
         get_info();
     }
 
+// ----------------------------------------------------------------------------------------
+
+    long webp_loader::nr() const { return height_; }
+    long webp_loader::nc() const { return width_; }
+
 // ----------------------------------------------------------------------------------------
 
     void webp_loader::get_info()

dlib/image_loader/webp_loader.h

@@ -23,6 +23,9 @@ namespace dlib
         webp_loader(const dlib::file& f);
         webp_loader(const unsigned char* imgbuffer, size_t buffersize);
 
+        long nr() const;
+        long nc() const;
+
         template<typename image_type>
         void get_image(image_type& image) const
         {

dlib/image_loader/webp_loader_abstract.h

@@ -82,6 +82,22 @@ namespace dlib
                 - all resources associated with *this has been released
         !*/
 
+        long nr (
+        ) const;
+        /*!
+            ensures
+                - returns the number of rows (height) of the image contained by this
+                  object.
+        !*/
+
+        long nc (
+        ) const;
+        /*!
+            ensures
+                - returns the number of colums (width) of the image contained by this
+                  object.
+        !*/
+
         template<
             typename image_type 
             >