boost/gil/extension/io/png/detail/base.hpp

   1 //
   2 // Copyright 2012 Christian Henning
   3 //
   4 // Distributed under the Boost Software License, Version 1.0
   5 // See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt
   7 //
   8 #ifndef BOOST_GIL_EXTENSION_IO_PNG_DETAIL_BASE_HPP
   9 #define BOOST_GIL_EXTENSION_IO_PNG_DETAIL_BASE_HPP
  10
  11 #include <boost/gil/extension/io/png/tags.hpp>
  12
  13 #include <boost/assert.hpp>
  14
  15 #include <memory>
  16
  17 namespace boost { namespace gil { namespace detail {
  18
  19 struct png_ptr_wrapper
  20 {
  21     png_ptr_wrapper()
  22     : _struct( nullptr )
  23     , _info  ( nullptr )
  24     {}
  25
  26     png_structp _struct;
  27     png_infop   _info;
  28 };
  29
  30 ///
  31 /// Wrapper for libpng's png_struct and png_info object. Implements value semantics.
  32 ///
  33 struct png_struct_info_wrapper
  34 {
  35 protected:
  36
  37     using png_ptr_t = std::shared_ptr<png_ptr_wrapper>;
  38
  39 protected:
  40
  41     ///
  42     /// Default Constructor
  43     ///
  44     png_struct_info_wrapper( bool read = true )
  45     : _png_ptr( new png_ptr_wrapper()
  46               , ( ( read ) ? png_ptr_read_deleter : png_ptr_write_deleter )
  47               )
  48     {}
  49
  50     png_ptr_wrapper*       get()       { return _png_ptr.get(); }
  51     png_ptr_wrapper const* get() const { return _png_ptr.get(); }
  52
  53     png_struct*       get_struct()       { return get()->_struct; }
  54     png_struct const* get_struct() const { return get()->_struct; }
  55
  56     png_info*       get_info()       { return get()->_info; }
  57     png_info const* get_info() const { return get()->_info; }
  58
  59 private:
  60
  61     static void png_ptr_read_deleter( png_ptr_wrapper* png_ptr )
  62     {
  63         if( png_ptr )
  64         {
  65             if( png_ptr->_struct && png_ptr->_info )
  66             {
  67                 png_destroy_read_struct( &png_ptr->_struct
  68                                        , &png_ptr->_info
  69                                        , nullptr
  70                                        );
  71             }
  72
  73             delete png_ptr;
  74             png_ptr = nullptr;
  75         }
  76     }
  77
  78     static void png_ptr_write_deleter( png_ptr_wrapper* png_ptr )
  79     {
  80         if( png_ptr )
  81         {
  82             if( png_ptr->_struct && png_ptr->_info )
  83             {
  84                 png_destroy_write_struct( &png_ptr->_struct
  85                                         , &png_ptr->_info
  86                                         );
  87             }
  88
  89             delete png_ptr;
  90             png_ptr = nullptr;
  91         }
  92     }
  93
  94
  95 private:
  96
  97     png_ptr_t _png_ptr;
  98 };
  99
 100 } // namespace detail
 101 } // namespace gil
 102 } // namespace boost
 103
 104 #endif