[transfix]

Why

On this Windows dev box, three tests always failed, and we had been writing them off as "ImageMagick has no decode delegate here": ImageTest.ReadsCmykInputAsRgb, CvcCliTest.Vol2ImgExportsSlices and CvcCliTest.Img2VolImportsSlices. They failed for three separate reasons. CI only passed because its Windows test step exports MAGICK_CODER_MODULE_PATH, MAGICK_FILTER_MODULE_PATH and MAGICK_CONFIGURE_PATH.

1. libcvc looked for ImageMagick's coders in the wrong places. cvcpkg's ImageMagick is extracted, not installed, so Magick has no coders at all (not even xc:) until something points it at them. set_magick_paths_win() tried three places:

   • the directory of cvc.dll;
   • a fixed ..\..\..\..\deps\bin relative to it;
   • CVC_DEPS_PREFIX/CVCPKG_PREFIX.

   In a dev build cvc.dll is in build\bin, while the coders sit beside CORE_RL_MagickCore_.dll in the deps prefix. None of the three matched.

2. Two code paths skipped that setup entirely.

   • vol_to_slices()/slices_to_volume() use Magick++ directly. So cvc vol2img failed with RegistryKeyLookupFailed CoderModulesPath even after (1) was fixed.
   • ImageTest.ReadsCmykInputAsRgb also uses Magick++ directly, calling a bare InitializeMagick. It passed in a full run, after other cases had initialized Magick, and failed alone. ctest always runs it alone.

3. cvc_cli_test couldn't find cvc when run directly. Its SetUp() called fs::canonical("/proc/self/exe"), which throws on Windows and macOS. Run without ctest's CVC_CLI_BINARY, every case failed.

What

• set_magick_paths_win() also tries the directory the ImageMagick DLL was loaded from, found two ways:

  • by name (CORE_RL_MagickCore_.dll, the name in the cvcpkg bundle);
  • by the address of one of its functions, for other builds.

  The existing candidates and the first-with-IM_MOD_RL_*.dll rule are unchanged, and a variable already set in the environment still wins.

• cvc::init_imagemagick() (new, image.h) exposes the once-only initializer that read_image/write_image already used. It is a no-op without ImageMagick. vol_to_slices(), slices_to_volume() and the CMYK test call it.

• cvc_cli_test finds cvc/cvc.exe beside itself:

  • GetModuleFileNameW on Windows;
  • _NSGetExecutablePath on macOS;
  • /proc/self/exe on Linux.

  If none works, it skips as it meant to, instead of throwing.

Tests (MSVC 14.38 Release, Windows, no MAGICK_* variables set)

• image_test 28/28, both in one process and with the CMYK case run alone.
• cvc_cli_test 173/173 run directly (before: every case failed in SetUp()). Under ctest, Vol2Img/Img2Vol now pass.
• Full ctest, 4065 cases: everything passes except StateClusterMembership.EventCallbacks, which failed once under -j 8 and passes 5 of 5 alone. That is the heartbeat-timing family noted in state: json, traverse and reset without recursing once per level #668.
• clang-format 18 is clean.

Found, not fixed

• cvc hexahedralize --improve crashes now and then with an access violation (0xC0000005). This hit CvcCliTest.Regression_MeshImproveMethodsNoCrash once in five runs and HexahedralizeMethodAndImproveFlags once in a full run. Both pass when repeated. It is unrelated to images.
• The pycvc ctest entries fail in a dev build tree. _pycvc adds only build\bin as a DLL directory, and Python 3.8+ ignores PATH, so the deps prefix's DLLs are never found. Registering the deps bin makes 20 of 22 scripts pass. (PR CI doesn't build pycvc.)