From 1f6649b7d118e9de2a51c9e48b5fea527f608fc1 Mon Sep 17 00:00:00 2001
From: Mateusz Loskot <mateusz@loskot.net>
Date: Tue, 17 Apr 2018 22:53:26 +0200
Subject: FindJPEG: Add version detection and associated test update and docs

---
 Modules/FindJPEG.cmake                        | 27 ++++++++++++++++++++++++++-
 Tests/CMakeOnly/AllFindModules/CMakeLists.txt |  2 +-
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/Modules/FindJPEG.cmake b/Modules/FindJPEG.cmake
index 04e4d20..9c047e5 100644
--- a/Modules/FindJPEG.cmake
+++ b/Modules/FindJPEG.cmake
@@ -18,12 +18,16 @@
 #   where to find jpeglib.h, etc.
 # ``JPEG_LIBRARIES``
 #   the libraries needed to use JPEG.
+# ``JPEG_VERSION``
+#   the version of the JPEG library found
 #
 # Cache variables
 # ^^^^^^^^^^^^^^^
 #
 # The following cache variables may also be set:
 #
+# ``JPEG_INCLUDE_DIR``
+#   where to find jpeglib.h, etc.
 # ``JPEG_LIBRARY``
 #   where to find the JPEG library.
 
@@ -32,8 +36,29 @@ find_path(JPEG_INCLUDE_DIR jpeglib.h)
 set(JPEG_NAMES ${JPEG_NAMES} jpeg libjpeg)
 find_library(JPEG_LIBRARY NAMES ${JPEG_NAMES})
 
+if(JPEG_INCLUDE_DIR AND EXISTS "${JPEG_INCLUDE_DIR}/jpeglib.h")
+  file(STRINGS "${JPEG_INCLUDE_DIR}/jpeglib.h"
+    jpeg_lib_version REGEX "^#define[\t ]+JPEG_LIB_VERSION[\t ]+.*")
+
+  if (NOT jpeg_lib_version)
+    # libjpeg-turbo sticks JPEG_LIB_VERSION in jconfig.h
+    find_path(jconfig_dir jconfig.h)
+    if (jconfig_dir)
+      file(STRINGS "${jconfig_dir}/jconfig.h"
+        jpeg_lib_version REGEX "^#define[\t ]+JPEG_LIB_VERSION[\t ]+.*")
+    endif()
+    unset(jconfig_dir)
+  endif()
+
+  string(REGEX REPLACE "^#define[\t ]+JPEG_LIB_VERSION[\t ]+([0-9]+).*"
+    "\\1" JPEG_VERSION "${jpeg_lib_version}")
+  unset(jpeg_lib_version)
+endif()
+
 include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
-find_package_handle_standard_args(JPEG DEFAULT_MSG JPEG_LIBRARY JPEG_INCLUDE_DIR)
+find_package_handle_standard_args(JPEG
+  REQUIRED_VARS JPEG_LIBRARY JPEG_INCLUDE_DIR
+  VERSION_VAR JPEG_VERSION)
 
 if(JPEG_FOUND)
   set(JPEG_LIBRARIES ${JPEG_LIBRARY})
diff --git a/Tests/CMakeOnly/AllFindModules/CMakeLists.txt b/Tests/CMakeOnly/AllFindModules/CMakeLists.txt
index 443d366..a53e441 100644
--- a/Tests/CMakeOnly/AllFindModules/CMakeLists.txt
+++ b/Tests/CMakeOnly/AllFindModules/CMakeLists.txt
@@ -86,7 +86,7 @@ foreach(VTEST ALSA ARMADILLO BZIP2 CUPS CURL EXPAT FREETYPE GETTEXT GIT HG
 endforeach()
 
 foreach(VTEST BISON Boost CUDA DOXYGEN FLEX GIF GTK2
-        HDF5 LibArchive OPENSCENEGRAPH RUBY SWIG Protobuf)
+        HDF5 JPEG LibArchive OPENSCENEGRAPH RUBY SWIG Protobuf)
     check_version_string(${VTEST} ${VTEST}_VERSION)
 endforeach()
 
-- 
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