png/detail/base.hpp

0001 //
0002 // Copyright 2012 Christian Henning
0003 //
0004 // Distributed under the Boost Software License, Version 1.0
0005 // See accompanying file LICENSE_1_0.txt or copy at
0006 // http://www.boost.org/LICENSE_1_0.txt
0007 //
0008 #ifndef BOOST_GIL_EXTENSION_IO_PNG_DETAIL_BASE_HPP
0009 #define BOOST_GIL_EXTENSION_IO_PNG_DETAIL_BASE_HPP
0010
0011 #include <boost/gil/extension/io/png/tags.hpp>
0012
0013 #include <boost/assert.hpp>
0014
0015 #include <memory>
0016
0017 namespace boost { namespace gil { namespace detail {
0018
0019 struct png_ptr_wrapper
0020 {
0021     png_ptr_wrapper()
0022     : _struct( nullptr )
0023     , _info  ( nullptr )
0024     {}
0025
0026     png_structp _struct;
0027     png_infop   _info;
0028 };
0029
0030 ///
0031 /// Wrapper for libpng's png_struct and png_info object. Implements value semantics.
0032 ///
0033 struct png_struct_info_wrapper
0034 {
0035 protected:
0036
0037     using png_ptr_t = std::shared_ptr<png_ptr_wrapper>;
0038
0039 protected:
0040
0041     ///
0042     /// Default Constructor
0043     ///
0044     png_struct_info_wrapper( bool read = true )
0045     : _png_ptr( new png_ptr_wrapper()
0046               , ( ( read ) ? png_ptr_read_deleter : png_ptr_write_deleter )
0047               )
0048     {}
0049
0050     png_ptr_wrapper*       get()       { return _png_ptr.get(); }
0051     png_ptr_wrapper const* get() const { return _png_ptr.get(); }
0052
0053     png_struct*       get_struct()       { return get()->_struct; }
0054     png_struct const* get_struct() const { return get()->_struct; }
0055
0056     png_info*       get_info()       { return get()->_info; }
0057     png_info const* get_info() const { return get()->_info; }
0058
0059 private:
0060
0061     static void png_ptr_read_deleter( png_ptr_wrapper* png_ptr )
0062     {
0063         if( png_ptr )
0064         {
0065             if( png_ptr->_struct && png_ptr->_info )
0066             {
0067                 png_destroy_read_struct( &png_ptr->_struct
0068                                        , &png_ptr->_info
0069                                        , nullptr
0070                                        );
0071             }
0072
0073             delete png_ptr;
0074             png_ptr = nullptr;
0075         }
0076     }
0077
0078     static void png_ptr_write_deleter( png_ptr_wrapper* png_ptr )
0079     {
0080         if( png_ptr )
0081         {
0082             if( png_ptr->_struct && png_ptr->_info )
0083             {
0084                 png_destroy_write_struct( &png_ptr->_struct
0085                                         , &png_ptr->_info
0086                                         );
0087             }
0088
0089             delete png_ptr;
0090             png_ptr = nullptr;
0091         }
0092     }
0093
0094
0095 private:
0096
0097     png_ptr_t _png_ptr;
0098 };
0099
0100 } // namespace detail
0101 } // namespace gil
0102 } // namespace boost
0103
0104 #endif