Support cmake config for libdeflate (#1613)

* Support cmake config and shared library for libdeflate

When not using the internal deflate, the only option was pkgconfig which
is not well supported on Windows. This adds support for using the
libdeflate cmake config files when available.

This change also affects the generated OpenEXR cmake config files. For
a static OpenEXR library, INTERFACE_LINK_LIBRARIES now appropriately
includes libdeflate along with the existing dependencies like Imath.

It also turns the internal libdeflate into a target for consistency.

Resolves #1588

Signed-off-by: Brecht Van Lommel <[email protected]>

* Back out of adding a target for internal libdeflate

Signed-off-by: Brecht Van Lommel <[email protected]>

* Use Requires.private for generated pkgconfig file

Signed-off-by: Brecht Van Lommel <[email protected]>

---------

Signed-off-by: Brecht Van Lommel <[email protected]>

cmake/OpenEXR.pc.in

@@ -14,7 +14,8 @@ Name: OpenEXR
 Description: OpenEXR image library
 Version: @OPENEXR_VERSION@
 
-Libs: @exr_pthread_libs@ -L${libdir} -lOpenEXR${libsuffix} -lOpenEXRUtil${libsuffix} -lOpenEXRCore${libsuffix} -lIex${libsuffix} -lIlmThread${libsuffix} @EXR_DEFLATE_LDFLAGS@
+Libs: @exr_pthread_libs@ -L${libdir} -lOpenEXR${libsuffix} -lOpenEXRUtil${libsuffix} -lOpenEXRCore${libsuffix} -lIex${libsuffix} -lIlmThread${libsuffix}
 Cflags: -I${includedir} -I${OpenEXR_includedir} @exr_pthread_cflags@
 Requires: Imath
+Requires.private: @EXR_DEFLATE_PKGCONFIG_REQUIRES@
 

cmake/OpenEXRSetup.cmake

@@ -160,15 +160,40 @@ set(OPENEXR_DEFLATE_TAG "v1.18" CACHE STRING "Tag to use for libdeflate source r
 if(NOT OPENEXR_FORCE_INTERNAL_DEFLATE)
   #TODO: ^^ Release should not clone from main, this is a place holder
   set(CMAKE_IGNORE_PATH "${CMAKE_CURRENT_BINARY_DIR}/_deps/deflate-src/config;${CMAKE_CURRENT_BINARY_DIR}/_deps/deflate-build/config")
-  include(FindPkgConfig)
-  pkg_check_modules(deflate IMPORTED_TARGET GLOBAL libdeflate)
-  set(CMAKE_IGNORE_PATH)
-  if (deflate_FOUND)
-    message(STATUS "Using libdeflate from ${deflate_LINK_LIBRARIES}")
+  # First try cmake config
+  find_package(libdeflate CONFIG QUIET)
+  if(libdeflate_FOUND)
+    if(TARGET libdeflate::libdeflate_shared)
+      set(EXR_DEFLATE_LIB libdeflate::libdeflate_shared)
+    else()
+      set(EXR_DEFLATE_LIB libdeflate::libdeflate_static)
+    endif()
+    set(EXR_DEFLATE_VERSION ${libdeflate_VERSION})
+    message(STATUS "Using libdeflate from ${libdeflate_DIR}")
+  else()
+    # If not found, try pkgconfig
+    find_package(PkgConfig)
+    if(PKG_CONFIG_FOUND)
+      include(FindPkgConfig)
+      pkg_check_modules(deflate IMPORTED_TARGET GLOBAL libdeflate)
+      if(deflate_FOUND)
+        set(EXR_DEFLATE_LIB PkgConfig::deflate)
+        set(EXR_DEFLATE_VERSION ${deflate_VERSION})
+        message(STATUS "Using libdeflate from ${deflate_LINK_LIBRARIES}")
+      endif()
+    endif()
   endif()
+  set(CMAKE_IGNORE_PATH)
 endif()
 
-if(NOT TARGET PkgConfig::deflate AND NOT deflate_FOUND)
+if(EXR_DEFLATE_LIB)
+  # Using external library
+  set(EXR_DEFLATE_SOURCES)
+  set(EXR_DEFLATE_INCLUDE_DIR)
+  # For OpenEXR.pc.in for static build
+  set(EXR_DEFLATE_PKGCONFIG_REQUIRES "libdeflate >= ${EXR_DEFLATE_VERSION}")
+else()
+  # Using internal deflate
   if(OPENEXR_FORCE_INTERNAL_DEFLATE)
     message(STATUS "libdeflate forced internal, installing from ${OPENEXR_DEFLATE_REPO} (${OPENEXR_DEFLATE_TAG})")
   else()
@@ -213,16 +238,6 @@ if(NOT TARGET PkgConfig::deflate AND NOT deflate_FOUND)
   list(TRANSFORM EXR_DEFLATE_SOURCES PREPEND ${deflate_SOURCE_DIR}/)
   set(EXR_DEFLATE_INCLUDE_DIR ${deflate_SOURCE_DIR})
   set(EXR_DEFLATE_LIB)
-else()
-  set(EXR_DEFLATE_INCLUDE_DIR)
-  set(EXR_DEFLATE_LIB ${deflate_LIBRARIES})
-  # set EXR_DEFATE_LDFLAGS for OpenEXR.pc.in for static build
-  if (BUILD_SHARED_LIBS)
-    set(EXR_DEFLATE_LDFLAGS "")
-  else()
-    set(EXR_DEFLATE_LDFLAGS "-l${deflate_LIBRARIES}")
-  endif()
-  set(EXR_DEFLATE_SOURCES)
 endif()
 
 #######################################