Неразрешенный внешний символ _png_init_io, указанный в функции _pixReadStreamPng
Под Windows 7 я загрузил и распаковал leptonica.zip, а затем выполнил следующие действия (для успешного запуска Cmake):
cd leptonica
mkdir build
cd build
set PATH=%PATH%;C:\OCR\additionalLibs\zlib-1.2.8\build\Debug;C:\OCR\additionalLibs\zlib-1.2.8\build;C:\OCR\additionalLibs\zlib-1.2.8
set PATH=%PATH%;C:\OCR\additionalLibs\lpng143;C:\OCR\additionalLibs\lpng143\build\Debug;C:\OCR\additionalLibs\lpng143\build
cmake ..
После этого я получаю:
-- Building for: Visual Studio 14 2015
-- The C compiler identification is MSVC 19.0.24213.1
-- The CXX compiler identification is MSVC 19.0.24213.1
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio
14.0/VC/bin/cl.exe
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio
14.0/VC/bin/cl.exe -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studi
o 14.0/VC/bin/cl.exe
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studi
o 14.0/VC/bin/cl.exe -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Could NOT find GIF (missing: GIF_LIBRARY GIF_INCLUDE_DIR)
-- Could NOT find JPEG (missing: JPEG_LIBRARY)
-- Found ZLIB: C:/OCR/additionalLibs/zlib-1.2.8/build/Debug/zlibd.lib (found ver
sion "1.2.8")
-- Found PNG: C:/OCR/additionalLibs/lpng143/build/Debug/png14d.lib (found versio
n "1.4.3")
-- Could NOT find TIFF (missing: TIFF_LIBRARY TIFF_INCLUDE_DIR)
-- Found PkgConfig: C:/Program Files/CMake/bin/pkg-config.exe (found version "0.
26")
-- Checking for module 'libwebp'
-- No package 'libwebp' found
-- Checking for module 'libopenjp2'
-- No package 'libopenjp2' found
-- Looking for include file dlfcn.h
-- Looking for include file dlfcn.h - not found
-- Looking for include file inttypes.h
-- Looking for include file inttypes.h - found
-- Looking for include file memory.h
-- Looking for include file memory.h - found
-- Looking for include file stdint.h
-- Looking for include file stdint.h - found
-- Looking for include file stdlib.h
-- Looking for include file stdlib.h - found
-- Looking for include file strings.h
-- Looking for include file strings.h - not found
-- Looking for include file string.h
-- Looking for include file string.h - found
-- Looking for include file sys/stat.h
-- Looking for include file sys/stat.h - found
-- Looking for include file sys/types.h
-- Looking for include file sys/types.h - found
-- Looking for include file unistd.h
-- Looking for include file unistd.h - not found
-- Looking for include file openjpeg-2.0/openjpeg.h
-- Looking for include file openjpeg-2.0/openjpeg.h - not found
-- Looking for include file openjpeg-2.1/openjpeg.h
-- Looking for include file openjpeg-2.1/openjpeg.h - not found
-- Looking for include file openjpeg-2.2/openjpeg.h
-- Looking for include file openjpeg-2.2/openjpeg.h - not found
-- Looking for fmemopen
-- Looking for fmemopen - not found
-- Check if the system is big endian
-- Searching 16 bit integer
-- Looking for stddef.h
-- Looking for stddef.h - found
-- Check size of unsigned short
-- Check size of unsigned short - done
-- Using unsigned short
-- Check if the system is big endian - little endian
-- Configuring done
-- Generating done
-- Build files have been written to: C:/OCR/leptonica-master/build
libjpeg, libtiff и libgif сознательно не рассматриваются, так как меня интересует только управление файлами png. Команда cmake выводит leptonica.sln файл решения. Затем я компилирую файл решения на Visual Studio (чтобы найти файл заголовков zlib.h ; zconf.h; png.h; pngconfig.h Я изменил каталоги INCLUDE, добавив: C:\OCR\ AdditionalLibs\zlib-1.2.8;C:\OCR\ AdditionalLibs\lpng143).
Но решение не компилируется из-за ошибок:
LNK2019 unresolved external symbol _png_init_io referenced in function _pixReadStreamPng leptonica
LNK2019 unresolved external symbol _png_init_io referenced in function _pixReadStreamPng leptonica
Ошибка исходит из файла pngio.h, который в pixReadStreamPng вызывает функцию png_init_io, определенный в png.h, Похоже, что реализация функции не найдена, есть ли дополнительные библиотеки, которые должны быть реализованы? Где png_init_io реализованы?
1 ответ
Он реализован в png.c библиотеки libpng, но он защищен #ifdef PNG_STDIO_SUPPORTED, который вы, возможно, не определили. Смотрите комментарии в png.c:
# ifdef PNG_STDIO_SUPPORTED
/* Initialize the default input/output functions for the PNG file. If you
* use your own read or write routines, you can call either png_set_read_fn()
* or png_set_write_fn() instead of png_init_io(). If you have defined
* PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
* function of your own because "FILE *" isn't necessarily available.
*/
void PNGAPI
png_init_io(png_structrp png_ptr, png_FILE_p fp)
{
png_debug(1, "in png_init_io");
if (png_ptr == NULL)
return;
png_ptr->io_ptr = (png_voidp)fp;
}
# endif
