FindImageMagick: Add ImageMagick_VERSION

This deprecates the ImageMagick_VERSION_STRING result variable.

Additionally, ImageMagick version is now determined by either mogrify
executable (if available), or from the `<magick/version.h>` header.

Issue: #27088

Help/release/dev/find-modules.rst

@@ -43,6 +43,10 @@ Find Modules
 * The :module:`FindIcotool` module now provides a ``Icotool_VERSION`` result
   variable.  The ``ICOTOOL_VERSION_STRING`` result variable is deprecated.
 
+* The :module:`FindImageMagick` module now provides an ``ImageMagick_VERSION``
+  result variable.  The ``ImageMagick_VERSION_STRING`` result variable is
+  deprecated.
+
 * The :module:`FindJasper` module now provides a ``Jasper_VERSION`` result
   variable.  The ``JASPER_VERSION_STRING`` result variable is deprecated.
 

Modules/FindImageMagick.cmake

@@ -82,11 +82,15 @@ Result Variables
 This module defines the following variables:
 
 ``ImageMagick_FOUND``
-  Boolean indicating whether ImageMagick and all its requested components are
-  found.
+  Boolean indicating whether (the requested version of) ImageMagick and all
+  its requested components are found.
 
-``ImageMagick_VERSION_STRING``
-  The version of ImageMagick found.
+``ImageMagick_VERSION``
+  .. versionadded:: 4.2
+
+  The version of ImageMagick found in form of
+  ``<major>.<minor>.<patch>-<addendum>`` (e.g., ``6.9.12-98``, where ``98``
+  is the addendum release number).
 
   .. note::
 
@@ -131,6 +135,17 @@ The following cache variables may also be set:
 ``ImageMagick_EXECUTABLE_DIR``
   The full path to directory containing ImageMagick executables.
 
+Deprecated Variables
+^^^^^^^^^^^^^^^^^^^^
+
+The following variables are provided for backward compatibility:
+
+``ImageMagick_VERSION_STRING``
+  .. deprecated:: 4.2
+    Use ``ImageMagick_VERSION``, which has the same value.
+
+  The version of ImageMagick found.
+
 Examples
 ^^^^^^^^
 
@@ -143,6 +158,10 @@ target:
   target_link_libraries(example PRIVATE ImageMagick::Magick++)
 #]=======================================================================]
 
+cmake_policy(PUSH)
+cmake_policy(SET CMP0140 NEW)
+cmake_policy(SET CMP0159 NEW) # file(STRINGS) with REGEX updates CMAKE_MATCH_<n>
+
 find_package(PkgConfig QUIET)
 
 #---------------------------------------------------------------------
@@ -257,6 +276,60 @@ function(FIND_IMAGEMAGICK_EXE component)
   endif()
 endfunction()
 
+function(_ImageMagick_GetVersion)
+  unset(version)
+
+  if(ImageMagick_mogrify_EXECUTABLE)
+    execute_process(
+      COMMAND ${ImageMagick_mogrify_EXECUTABLE} -version
+      OUTPUT_VARIABLE version
+      ERROR_QUIET
+      OUTPUT_STRIP_TRAILING_WHITESPACE
+    )
+
+    if(version MATCHES "^Version: ImageMagick ([-0-9.]+)")
+      set(version "${CMAKE_MATCH_1}")
+    endif()
+  elseif(ImageMagick_INCLUDE_DIRS)
+    # MagickLibSubversion was used in ImageMagick <= 6.5.
+    set(
+      regex
+      "^[\t ]*#[\t ]*define[\t ]+(MagickLibVersionText|MagickLibAddendum|MagickLibSubversion)[\t ]+\"([-0-9.]+)\""
+    )
+
+    foreach(dir IN LISTS ImageMagick_INCLUDE_DIRS)
+      if(EXISTS ${dir}/magick/version.h)
+        file(STRINGS "${dir}/magick/version.h" results REGEX "${regex}")
+
+        foreach(line ${results})
+          if(line MATCHES "${regex}")
+            if(DEFINED version)
+              string(APPEND version "${CMAKE_MATCH_2}")
+            else()
+              set(version "${CMAKE_MATCH_2}")
+            endif()
+
+            if(CMAKE_MATCH_1 STREQUAL "MagickLibAddendum")
+              break()
+            endif()
+          endif()
+        endforeach()
+      endif()
+
+      if(DEFINED version)
+        break()
+      endif()
+    endforeach()
+  endif()
+
+  if(DEFINED version)
+    set(ImageMagick_VERSION "${version}")
+    set(ImageMagick_VERSION_STRING "${ImageMagick_VERSION}")
+  endif()
+
+  return(PROPAGATE ImageMagick_VERSION ImageMagick_VERSION_STRING)
+endfunction()
+
 #---------------------------------------------------------------------
 # Start Actual Work
 #---------------------------------------------------------------------
@@ -344,16 +417,7 @@ endif()
 set(ImageMagick_INCLUDE_DIRS ${ImageMagick_INCLUDE_DIRS})
 set(ImageMagick_LIBRARIES ${ImageMagick_LIBRARIES})
 
-if(ImageMagick_mogrify_EXECUTABLE)
-  execute_process(COMMAND ${ImageMagick_mogrify_EXECUTABLE} -version
-                  OUTPUT_VARIABLE imagemagick_version
-                  ERROR_QUIET
-                  OUTPUT_STRIP_TRAILING_WHITESPACE)
-  if(imagemagick_version MATCHES "^Version: ImageMagick ([-0-9\\.]+)")
-    set(ImageMagick_VERSION_STRING "${CMAKE_MATCH_1}")
-  endif()
-  unset(imagemagick_version)
-endif()
+_ImageMagick_GetVersion()
 
 #---------------------------------------------------------------------
 # Standard Package Output
@@ -361,7 +425,7 @@ endif()
 include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(ImageMagick
                                   REQUIRED_VARS ${ImageMagick_REQUIRED_VARS}
-                                  VERSION_VAR ImageMagick_VERSION_STRING
+                                  VERSION_VAR ImageMagick_VERSION
   )
 
 #---------------------------------------------------------------------
@@ -387,3 +451,5 @@ mark_as_advanced(
   IMAGEMAGICK_MONTAGE_EXECUTABLE
   IMAGEMAGICK_COMPOSITE_EXECUTABLE
   )
+
+cmake_policy(POP)

Tests/CMakeOnly/AllFindModules/CMakeLists.txt

@@ -99,7 +99,7 @@ foreach(
     FREETYPE
     GETTEXT GIT GNUTLS
     HG HSPELL
-    ICOTOOL
+    ICOTOOL ImageMagick
     JASPER
     LIBLZMA LIBXML2 LIBXSLT LTTNGUST
     OpenCL
@@ -122,7 +122,7 @@ foreach(
     FLEX Freetype
     Gettext GIF GnuTLS GNUTLS GTK2
     HDF5 Hg HSPELL
-    Icotool
+    Icotool ImageMagick
     Jasper JPEG
     LibArchive LibLZMA LIBLZMA LibXml2 LibXslt LTTngUST
     OpenCL OpenSceneGraph OPENSCENEGRAPH OpenSSL OPENSSL

Tests/FindImageMagick/Test/CMakeLists.txt

@@ -6,6 +6,10 @@ find_package(ImageMagick REQUIRED COMPONENTS Magick++ MagickWand)
 
 add_executable(test_magick++ main_magick++.cxx)
 target_link_libraries(test_magick++ PRIVATE ImageMagick::Magick++)
+target_compile_definitions(
+  test_magick++
+  PRIVATE CMAKE_EXPECTED_IMAGEMAGICK_VERSION="${ImageMagick_VERSION}"
+)
 add_test(NAME test_magick++ COMMAND test_magick++)
 
 add_executable(test_magick_wand main_magick_wand.c)

Tests/FindImageMagick/Test/main_magick++.cxx

@@ -1,3 +1,4 @@
+#include <cstring>
 #include <iostream>
 #include <string>
 
@@ -6,5 +7,14 @@
 int main()
 {
   Magick::InitializeMagick("");
-  return 0;
+
+  std::string found_version =
+    std::string(MagickLibVersionText) + MagickLibAddendum;
+
+  std::cout << "Found ImageMagick version " << found_version
+            << ", expected version " << CMAKE_EXPECTED_IMAGEMAGICK_VERSION
+            << "\n";
+
+  return std::strcmp(found_version.c_str(),
+                     CMAKE_EXPECTED_IMAGEMAGICK_VERSION);
 }