I believe it is necessary, yes. It ensures that you are actually linking with libjpeg-turbo.
The most common means of linking against libjpeg-turbo requires using the libjpeg-turbo SDK, which installs in a path that won't be found by FindJPEG.cmake. Thus, there is a high potential for user error if we don't perform this check. A user could, for instance, specify JPEG_INCLUDE_DIR and pick up the proper header file in /opt/libjpeg-turbo/include, but they could forget to specify JPEG_LIBRARIES. Without the run-time check, they will get "bogus colorspace" errors, which are hard to debug. I wouldn't have added the code if I hadn't made that mistake myself! I think the right thing to do would be to move the tests into a separate CMake file (FindLibjpegTurbo.cmake or whatever) and use the "new" test if not in a cross-compilation environment, otherwise use the old test. I'll look into that. On 8/1/11 3:27 AM, Peter Åstrand wrote: > > Is this really necessary? It makes it more difficult to cross compile. > Now I get: > > -- Found JPEG: /usr/i686-pc-mingw32/sys-root/mingw/lib/libjpeg.dll.a > -- Performing Test FOUND_LIBJPEG_TURBO > CMake Error: TRY_RUN() invoked in cross-compiling mode, please set the > following cache variables appropriately: > FOUND_LIBJPEG_TURBO_EXITCODE (advanced) > For details see /home/astrand/thin/vnc/tigervnc/trunk/TryRunResults.cmake > -- Performing Test FOUND_LIBJPEG_TURBO - Failed > > I can work around this by setting -DFOUND_LIBJPEG_TURBO_EXITCODE=0, but > I don't think it should be this complicated. > > Rgds, > Peter > > On Thu, 28 Jul 2011, dcomman...@users.sourceforge.net wrote: > >> Revision: 4602 >> http://tigervnc.svn.sourceforge.net/tigervnc/?rev=4602&view=rev >> Author: dcommander >> Date: 2011-07-28 08:06:39 +0000 (Thu, 28 Jul 2011) >> >> Log Message: >> ----------- >> Actually link and run the libjpeg-turbo test program to ensure that >> JPEG_LIBRARY is set correctly >> >> Modified Paths: >> -------------- >> trunk/CMakeLists.txt >> >> Modified: trunk/CMakeLists.txt >> =================================================================== >> --- trunk/CMakeLists.txt 2011-07-28 07:22:39 UTC (rev 4601) >> +++ trunk/CMakeLists.txt 2011-07-28 08:06:39 UTC (rev 4602) >> @@ -13,6 +13,7 @@ >> include(CheckTypeSize) >> include(CheckCSourceCompiles) >> include(CheckCXXSourceCompiles) >> +include(CheckCSourceRuns) >> >> include(CMakeMacroLibtoolFile) >> >> @@ -176,11 +177,28 @@ >> # Warn if it doesn't seem to be the accelerated libjpeg that's found >> set(CMAKE_REQUIRED_LIBRARIES ${JPEG_LIBRARIES}) >> set(CMAKE_REQUIRED_FLAGS -I${JPEG_INCLUDE_DIR}) >> +if(MSVC) >> + set(CMAKE_REQUIRED_DEFINITIONS -MT) >> +endif() >> >> -check_c_source_compiles("#include <stdio.h>\n#include >> <jpeglib.h>\nint main(int c, char** v) { return JCS_EXT_RGBX; }" >> FOUND_LIBJPEG_TURBO) >> +check_c_source_runs("\n >> + #include <stdio.h>\n >> + #include <jpeglib.h>\n >> + int main(void) {\n >> + struct jpeg_compress_struct cinfo;\n >> + struct jpeg_error_mgr jerr;\n >> + cinfo.err=jpeg_std_error(&jerr);\n >> + jpeg_create_compress(&cinfo);\n >> + cinfo.input_components = 3;\n >> + jpeg_set_defaults(&cinfo);\n >> + cinfo.in_color_space = JCS_EXT_RGB;\n >> + jpeg_default_colorspace(&cinfo);\n >> + return 0;\n >> + }" FOUND_LIBJPEG_TURBO) >> >> set(CMAKE_REQUIRED_LIBRARIES) >> set(CMAKE_REQUIRED_FLAGS) >> +set(CMAKE_REQUIRED_DEFINITIONS) >> >> if(NOT FOUND_LIBJPEG_TURBO) >> message(STATUS "WARNING: You are not using libjpeg-turbo. >> Performance will suffer.") >> >> >> This was sent by the SourceForge.net collaborative development >> platform, the world's largest Open Source development site. >> >> ------------------------------------------------------------------------------ >> >> Got Input? Slashdot Needs You. >> Take our quick survey online. Come on, we don't ask for help often. >> Plus, you'll get a chance to win $100 to spend on ThinkGeek. >> http://p.sf.net/sfu/slashdot-survey >> _______________________________________________ >> Tigervnc-commits mailing list >> tigervnc-comm...@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/tigervnc-commits >> > > > --- > Peter Åstrand ThinLinc Chief Developer > Cendio AB http://www.cendio.com > Wallenbergs gata 4 > 583 30 Linköping Phone: +46-13-21 46 00 > > > ------------------------------------------------------------------------------ > Got Input? Slashdot Needs You. > Take our quick survey online. Come on, we don't ask for help often. > Plus, you'll get a chance to win $100 to spend on ThinkGeek. > http://p.sf.net/sfu/slashdot-survey > > > > _______________________________________________ > Tigervnc-devel mailing list > Tigervnc-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/tigervnc-devel ------------------------------------------------------------------------------ Got Input? Slashdot Needs You. Take our quick survey online. Come on, we don't ask for help often. Plus, you'll get a chance to win $100 to spend on ThinkGeek. http://p.sf.net/sfu/slashdot-survey _______________________________________________ Tigervnc-devel mailing list Tigervnc-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tigervnc-devel
