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FreeImage and MinGW / LCC WIN 32
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================================
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This file explains how to create a FreeImage.a file from the FreeImage DLL, so that it can be linked with the MinGW / LCC WIN 32 / GNU gcc C compiler.
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1) Open a DOS shell (run the program cmd.exe)
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2) Add the MinGW path to your environment variable :
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C:\>set PATH=%PATH%;C:\mingw32\bin;
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3) Creates a .def file from the FreeImage DLL
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C:\>pexports freeimage.dll | sed "s/^_//" > freeimage_gcc.def
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4) Creates the FreeImage.a file
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C:\>dlltool -U -d freeimage_gcc.def -l freeimage.a
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Note : you may also use a batch file to automate this process :
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set PATH=%PATH%;C:\mingw32\bin;
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pexports freeimage.dll | sed "s/^_//" > freeimage_gcc.def
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dlltool -U -d freeimage_gcc.def -l libfreeimage.a
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Here are some links on the use of WIN32 DLL with the GNU C compiler :
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=====================================================================
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A Moron's Guide to Using Microsoft DLL's when Compiling Cygwin or Mingw Programs
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http://www.emmestech.com/software/cygwin/pexports-0.43/moron1.html
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==> About GNU tools and DLL
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Introduction to (mostly) GNU Programming Tools
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http://webclub.kcom.ne.jp/ma/colinp/win32/tools/index.html
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These pages are dealing with the use of Win32 DLL :
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The DLL Import Library Tool
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http://webclub.kcom.ne.jp/ma/colinp/win32/tools/dlltool.html
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Using Dynamic Link Libraries
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http://webclub.kcom.ne.jp/ma/colinp/win32/dll/use.html
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=====================================================================
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Using the FreeImage library with the MinGW Compiler Suite
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=====================================================================
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This file describes how to use the precompiled FreeImage library
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FreeImage.dll with the MinGW port of the GNU Compiler Collection
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(GCC), how to build this library from source using MinGW and how
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to use this MinGW-built library with Microsoft Visual Studio.
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1. Using the precompiled FreeImage library with MinGW
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2. Building the FreeImage library with MinGW
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3. Using the MinGW FreeImage library with Microsoft Visual Studio
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---------------------------------------------------------------------
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=====================================================================
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The procedures described in this document have been developed and
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tested using the following free tools:
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1. MinGW GCC Version 4.4.0 (Core and C++ including required libs)
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2. MinGW GNU Binutils Version 2.19.1
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3. MinGW GNU Make Version 3.81-20080326-3
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4. MinGW Runtime Version 3.15.2
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5. MinGW API for MS-Windows Version 3.13
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6. GnuWin32 Package CoreUtils Version 5.3.0 (only for building)
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7. GnuWin32 Package Sed Version 4.2 (only for creating the GCC
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* Sed is only needed to create a GCC-native import library from
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the MSVC import library FreeImage.lib. However, since MinGW now
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supports linking against MSVC lib files, this process seems to
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be obsolete. See section 1.
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Basically, no version dependent capabilities are used so, this
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should also work with older versions of the tools mentioned above.
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Similarly, the GnuWin32 packages (which I just prefer over MSYS)
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could likely be replaced by a properly installed MSYS environment.
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Furthermore, the following preconditions should be met:
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1. The folders 'bin' under both the MinGW and the GnuWin32
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installation directory should have been added to the PATH
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environment variable. Likely it is best adding these
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directories permanently to PATH through the System
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Properties dialog on the Control Panel.
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2. The MinGW Make package only provides a 'mingw32-make.exe'
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executable. There is no alias 'make.exe'. However, make is
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preconfigured to use 'make' as the default $(MAKE) command.
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This seems to be a bug in the MinGW GNU Make distribution.
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Thus, a copy of 'mingw32-make.exe' named 'make.exe' should
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be placed into MinGW's 'bin' directory.
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---------------------------------------------------------------------
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1. Using the precompiled FreeImage library with MinGW
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=====================================================================
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When using functions from C/C++, that reside in a DLL, the linker
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needs a so called import library, which specifies, how to
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dynamically link these external functions during runtime. However,
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different linkers use different types or formats of these import
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Since the precompiled FreeImage library was build with Microsoft
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Visual Studio, in the past, some extra work was required to use it
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from MinGW. An import library, that was compatible with GNU ld,
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must have been created first.
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However, for several MinGW versions, the GNU linker ld also
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supports linking against Microsoft Visual C++ import libraries
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directly. So, this effectively makes any circulating HOWTO's on
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how to create a GCC-compatible import library from a MSVC lib file
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more or less obsolete. Additionally, MinGW does not require the
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GCC/Linux usual lib prefix for libraries, so linking with MinGW
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against the precompiled FreeImage DLL is as easy as with MSVC:
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1.) Open a DOS shell (run application cmd.exe)
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2.) Ensure, that the 'bin' folder of MinGW is added to the PATH
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environment variable (see Prerequisites).
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3.) Link directly against the supplied lib file:
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C:\>gcc -oFreeImageTest.exe FreeImageTest.c -lFreeImage
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Nonetheless, for the sake of completeness, the following steps
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describe how to create a native GCC import library:
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1.) Open a DOS shell (run application cmd.exe)
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2.) Ensure, that the 'bin' folders of both MinGW and GnuWin32 are
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added to the PATH environment variable (see Prerequisites).
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3.) Create a .def file 'libfreeimage.def', that contains all symbols
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exported by the FreeImage library:
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C:\>pexports FreeImage.dll | sed "s/^_//" > libfreeimage.def
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4.) Create the GCC compatible import library 'libfreeimage.a':
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C:\>dlltool --add-underscore -d libfreeimage.def -l libfreeimage.a
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5.) Use this library to link against with GCC:
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C:\>gcc -oFreeImageTest.exe FreeImageTest.c -lfreeimage
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---------------------------------------------------------------------
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2. Building the FreeImage library with MinGW
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=====================================================================
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You *do not* need to have any other third party library (like
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libjpeg, libpng, libtiff, libmng and zlib and others) installed on
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your system in order to compile and use the library. FreeImage uses
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its own versions of these libraries. This way, you can be sure that
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FreeImage will always use the latest and properly tested versions
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of of these third party libraries.
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In order to build the FreeImage library under Windows with MinGW
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(GCC), ensure that all the prerequisites mentioned above are met.
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The MinGW makefile aims to build a Windows DLL, that differs as
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least as possible from the precompiled library that comes with the
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FreeImage distribution. Thus, the build process also includes the
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DLL version resource as well as the __stdcall attribute for all the
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exported functions, including the MSVC-like function decorations
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When building the FreeImage DLL, of course, an import library is
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generated, too. However, this input library is not in GCC's native
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format, but in MSVC lib format, which makes it usable from both
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MinGW and Microsoft Visual Studio with no further processing.
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The MinGW makefile can also be used to build a static library.
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However, due to the different function export attributes needed
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for both the dynamic and the shared library (DLL), this requires
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a separate invocation of make, which in turn needs to rebuild every
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source file after switching from dynamic to static and vice versa.
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So, a 'make clean' is required each time, the library type is
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The type of library to build is specified by a variable named
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FREEIMAGE_LIBRARY_TYPE, which may either be set directly in the
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Makefile.mingw near line 18 or may be specified as an environment
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variable. This variable may either take SHARED or STATIC to build
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a dynamic link library (DLL) or a static library respectively.
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Since this value is used to dynamically form the actual make target
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internally, only uppercase values are valid. Defaults to SHARED.
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The MinGW makefile also supports the 'install' target. However,
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this only copies the FreeImage dynamic link library (DLL) from the
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Dist folder into the %SystemRoot%\system32 folder. So, invoking this
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target only makes sense, if the DLL has been built before.
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Since there is neither a common system wide 'include' nor a 'lib'
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directory available under Windows, the FreeImage header file
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FreeImage.h as well as both the static library and the DLL import
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library FreeImage.lib just remain in the 'Dist' folder.
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The following procedure creates the FreeImage dynamic link library
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(DLL) from the sources, installs it and also creates a static
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1.) Open a DOS shell (run application cmd.exe)
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2.) Ensure, that the 'bin' folders of both MinGW and GnuWin32 are
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added to the PATH environment variable (see Prerequisites).
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3.) Create the FreeImage dynamic link library (DLL):
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4.) Install the FreeImage dynamic link library (DLL):
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5.) Clean all files produced by the recent build process:
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6.) Create a static FreeImage library:
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C:\>set FREEIMAGE_LIBRARY_TYPE=STATIC
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You should be able to link progams with the -lFreeImage option
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after the shared library is compiled and installed. You can also
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link statically against FreeImage.a from MinGW.
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---------------------------------------------------------------------
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3. Using the MinGW FreeImage library with Microsoft Visual Studio
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=====================================================================
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Since the MinGW makefile creates an import library in MSVC's lib
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format, the produced shared library (DLL) can be used from both
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MinGW and Microsoft Visual Studio with no further adaption. Just
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link to the import library FreeImage.lib from either MinGW or
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Microsoft Visual Studio.
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---------------------------------------------------------------------
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=====================================================================
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- The MinGW homepage:
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http://www.mingw.org/
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- The GnuWin32 homepage:
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http://gnuwin32.sourceforge.net/
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- The GCC homepage and online documentation:
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http://gcc.gnu.org/onlinedocs/
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- The GNU Binutils homepage and online documentation:
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http://www.gnu.org/software/binutils/
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http://sourceware.org/binutils/docs-2.19/
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- The GNU Make homepage and online documentation:
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http://www.gnu.org/software/make/
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http://www.gnu.org/software/make/manual/make.html
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README.minGW
