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// Copyright (C) 2008 Davis E. King (davis@dlib.net), Nils Labugt
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_PNG_LOADER_CPp_
#define DLIB_PNG_LOADER_CPp_
// only do anything with this file if DLIB_PNG_SUPPORT is defined
#ifdef DLIB_PNG_SUPPORT
#include "../array2d.h"
#include "../pixel.h"
#include "../dir_nav.h"
#include "png_loader.h"
#include <png.h>
#include "../string.h"
#include "../byte_orderer.h"
#include <sstream>
#include <cstring>
namespace dlib
{
// ----------------------------------------------------------------------------------------
struct LibpngData
{
png_bytep* row_pointers_;
png_structp png_ptr_;
png_infop info_ptr_;
png_infop end_info_;
};
// ----------------------------------------------------------------------------------------
png_loader::
png_loader( const char* filename ) : height_( 0 ), width_( 0 )
{
read_image( filename );
}
// ----------------------------------------------------------------------------------------
png_loader::
png_loader( const std::string& filename ) : height_( 0 ), width_( 0 )
{
read_image( filename.c_str() );
}
// ----------------------------------------------------------------------------------------
png_loader::
png_loader( const dlib::file& f ) : height_( 0 ), width_( 0 )
{
read_image( f.full_name().c_str() );
}
// ----------------------------------------------------------------------------------------
const unsigned char* png_loader::get_row( unsigned i ) const
{
return ld_->row_pointers_[i];
}
// ----------------------------------------------------------------------------------------
png_loader::~png_loader()
{
if ( ld_ && ld_->row_pointers_ != NULL )
png_destroy_read_struct( &( ld_->png_ptr_ ), &( ld_->info_ptr_ ), &( ld_->end_info_ ) );
}
// ----------------------------------------------------------------------------------------
bool png_loader::is_gray() const
{
return ( color_type_ == PNG_COLOR_TYPE_GRAY );
}
// ----------------------------------------------------------------------------------------
bool png_loader::is_graya() const
{
return ( color_type_ == PNG_COLOR_TYPE_GRAY_ALPHA );
}
// ----------------------------------------------------------------------------------------
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 );
}
// ----------------------------------------------------------------------------------------
// Don't do anything when libpng calls us to tell us about an error. Just return to
// our own code and throw an exception (at the long jump target).
void png_loader_user_error_fn_silent(png_structp png_struct, png_const_charp )
{
longjmp(png_jmpbuf(png_struct),1);
}
void png_loader_user_warning_fn_silent(png_structp , png_const_charp )
{
}
void png_loader::read_image( const char* filename )
{
ld_.reset(new LibpngData);
if ( filename == NULL )
{
throw image_load_error("png_loader: invalid filename, it is NULL");
}
FILE *fp = fopen( filename, "rb" );
if ( !fp )
{
throw image_load_error(std::string("png_loader: unable to open file ") + filename);
}
png_byte sig[8];
if (fread( sig, 1, 8, fp ) != 8)
{
fclose( fp );
throw image_load_error(std::string("png_loader: error reading file ") + filename);
}
if ( png_sig_cmp( sig, 0, 8 ) != 0 )
{
fclose( fp );
throw image_load_error(std::string("png_loader: format error in file ") + filename);
}
ld_->png_ptr_ = png_create_read_struct( PNG_LIBPNG_VER_STRING, NULL, &png_loader_user_error_fn_silent, &png_loader_user_warning_fn_silent );
if ( ld_->png_ptr_ == NULL )
{
fclose( fp );
std::ostringstream sout;
sout << "Error, unable to allocate png structure while opening file " << filename << std::endl;
const char* runtime_version = png_get_header_ver(NULL);
if (runtime_version && std::strcmp(PNG_LIBPNG_VER_STRING, runtime_version) != 0)
{
sout << "This is happening because you compiled against one version of libpng, but then linked to another." << std::endl;
sout << "Compiled against libpng version: " << PNG_LIBPNG_VER_STRING << std::endl;
sout << "Linking to this version of libpng: " << runtime_version << std::endl;
}
throw image_load_error(sout.str());
}
ld_->info_ptr_ = png_create_info_struct( ld_->png_ptr_ );
if ( ld_->info_ptr_ == NULL )
{
fclose( fp );
png_destroy_read_struct( &( ld_->png_ptr_ ), ( png_infopp )NULL, ( png_infopp )NULL );
throw image_load_error(std::string("png_loader: parse error in file ") + filename);
}
ld_->end_info_ = png_create_info_struct( ld_->png_ptr_ );
if ( ld_->end_info_ == NULL )
{
fclose( fp );
png_destroy_read_struct( &( ld_->png_ptr_ ), &( ld_->info_ptr_ ), ( png_infopp )NULL );
throw image_load_error(std::string("png_loader: parse error in file ") + filename);
}
if (setjmp(png_jmpbuf(ld_->png_ptr_)))
{
// If we get here, we had a problem writing the file
fclose(fp);
png_destroy_read_struct( &( ld_->png_ptr_ ), &( ld_->info_ptr_ ), &( ld_->end_info_ ) );
throw image_load_error(std::string("png_loader: parse error in file ") + filename);
}
png_set_palette_to_rgb(ld_->png_ptr_);
png_init_io( ld_->png_ptr_, fp );
png_set_sig_bytes( ld_->png_ptr_, 8 );
// flags force one byte per channel output
byte_orderer bo;
int png_transforms = PNG_TRANSFORM_PACKING;
if (bo.host_is_little_endian())
png_transforms |= PNG_TRANSFORM_SWAP_ENDIAN;
png_read_png( ld_->png_ptr_, ld_->info_ptr_, png_transforms, NULL );
height_ = png_get_image_height( ld_->png_ptr_, ld_->info_ptr_ );
width_ = png_get_image_width( ld_->png_ptr_, ld_->info_ptr_ );
bit_depth_ = png_get_bit_depth( ld_->png_ptr_, ld_->info_ptr_ );
color_type_ = png_get_color_type( ld_->png_ptr_, ld_-> info_ptr_ );
if (color_type_ != PNG_COLOR_TYPE_GRAY &&
color_type_ != PNG_COLOR_TYPE_RGB &&
color_type_ != PNG_COLOR_TYPE_RGB_ALPHA &&
color_type_ != PNG_COLOR_TYPE_GRAY_ALPHA)
{
fclose( fp );
png_destroy_read_struct( &( ld_->png_ptr_ ), &( ld_->info_ptr_ ), &( ld_->end_info_ ) );
throw image_load_error(std::string("png_loader: unsupported color type in file ") + filename);
}
if (bit_depth_ != 8 && bit_depth_ != 16)
{
fclose( fp );
png_destroy_read_struct( &( ld_->png_ptr_ ), &( ld_->info_ptr_ ), &( ld_->end_info_ ) );
throw image_load_error("png_loader: unsupported bit depth of " + cast_to_string(bit_depth_) + " in file " + std::string(filename));
}
ld_->row_pointers_ = png_get_rows( ld_->png_ptr_, ld_->info_ptr_ );
fclose( fp );
if ( ld_->row_pointers_ == NULL )
{
png_destroy_read_struct( &( ld_->png_ptr_ ), &( ld_->info_ptr_ ), &( ld_->end_info_ ) );
throw image_load_error(std::string("png_loader: parse error in file ") + filename);
}
}
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_PNG_SUPPORT
#endif // DLIB_PNG_LOADER_CPp_
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