From 709ec152dfee669a992416e6769ff621cadd8ac7 Mon Sep 17 00:00:00 2001
From: Vincent Rabaud <vrabaud@google.com>
Date: Fri, 26 May 2023 00:14:05 +0200
Subject: [PATCH] Do not find_package image libraries if not needed.

This can be tested by running:
cmake ../ -DWEBP_BUILD_ANIM_UTILS=OFF -DWEBP_BUILD_CWEBP=OFF -DWEBP_BUILD_DWEBP=OFF -DWEBP_BUILD_GIF2WEBP=OFF -DWEBP_BUILD_IMG2WEBP=OFF -DWEBP_BUILD_EXTRAS=OFF

Bug: webp:612

Change-Id: Ie06d8f0535676d6d31ff0047ff7a6c026e16118e
---
 CMakeLists.txt   | 10 ++++++
 cmake/deps.cmake | 80 +++++++++++++++++++++++++-----------------------
 2 files changed, 51 insertions(+), 39 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a396e304..47a197d7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -99,6 +99,16 @@ if(NOT CMAKE_BUILD_TYPE)
 endif()
 
 # Include dependencies.
+if(WEBP_BUILD_ANIM_UTILS
+   OR WEBP_BUILD_CWEBP
+   OR WEBP_BUILD_DWEBP
+   OR WEBP_BUILD_EXTRAS
+   OR WEBP_BUILD_GIF2WEBP
+   OR WEBP_BUILD_IMG2WEBP)
+  set(WEBP_FIND_IMG_LIBS TRUE)
+else()
+  set(WEBP_FIND_IMG_LIBS FALSE)
+endif()
 include(cmake/deps.cmake)
 include(GNUInstallDirs)
 
diff --git a/cmake/deps.cmake b/cmake/deps.cmake
index 67641117..0760ba92 100644
--- a/cmake/deps.cmake
+++ b/cmake/deps.cmake
@@ -74,53 +74,55 @@ endif()
 # Find the standard image libraries.
 set(WEBP_DEP_IMG_LIBRARIES)
 set(WEBP_DEP_IMG_INCLUDE_DIRS)
-foreach(I_LIB PNG JPEG TIFF)
-  # Disable tiff when compiling in static mode as it is failing on Ubuntu.
-  if(WEBP_LINK_STATIC AND ${I_LIB} STREQUAL "TIFF")
-    message(STATUS "TIFF is disabled when statically linking.")
-    continue()
+if(WEBP_FIND_IMG_LIBS)
+  foreach(I_LIB PNG JPEG TIFF)
+    # Disable tiff when compiling in static mode as it is failing on Ubuntu.
+    if(WEBP_LINK_STATIC AND ${I_LIB} STREQUAL "TIFF")
+      message(STATUS "TIFF is disabled when statically linking.")
+      continue()
+    endif()
+    find_package(${I_LIB})
+    set(WEBP_HAVE_${I_LIB} ${${I_LIB}_FOUND})
+    if(${I_LIB}_FOUND)
+      list(APPEND WEBP_DEP_IMG_LIBRARIES ${${I_LIB}_LIBRARIES})
+      list(APPEND WEBP_DEP_IMG_INCLUDE_DIRS ${${I_LIB}_INCLUDE_DIR}
+           ${${I_LIB}_INCLUDE_DIRS})
+    endif()
+  endforeach()
+  if(WEBP_DEP_IMG_INCLUDE_DIRS)
+    list(REMOVE_DUPLICATES WEBP_DEP_IMG_INCLUDE_DIRS)
   endif()
-  find_package(${I_LIB})
-  set(WEBP_HAVE_${I_LIB} ${${I_LIB}_FOUND})
-  if(${I_LIB}_FOUND)
-    list(APPEND WEBP_DEP_IMG_LIBRARIES ${${I_LIB}_LIBRARIES})
-    list(APPEND WEBP_DEP_IMG_INCLUDE_DIRS ${${I_LIB}_INCLUDE_DIR}
-         ${${I_LIB}_INCLUDE_DIRS})
-  endif()
-endforeach()
-if(WEBP_DEP_IMG_INCLUDE_DIRS)
-  list(REMOVE_DUPLICATES WEBP_DEP_IMG_INCLUDE_DIRS)
-endif()
 
-# GIF detection, gifdec isn't part of the imageio lib.
-include(CMakePushCheckState)
-set(WEBP_DEP_GIF_LIBRARIES)
-set(WEBP_DEP_GIF_INCLUDE_DIRS)
-find_package(GIF)
-set(WEBP_HAVE_GIF ${GIF_FOUND})
-if(GIF_FOUND)
-  # GIF find_package only locates the header and library, it doesn't fail
-  # compile tests when detecting the version, but falls back to 3 (as of at
-  # least cmake 3.7.2). Make sure the library links to avoid incorrect detection
-  # when cross compiling.
-  cmake_push_check_state()
-  set(CMAKE_REQUIRED_LIBRARIES ${GIF_LIBRARIES})
-  set(CMAKE_REQUIRED_INCLUDES ${GIF_INCLUDE_DIR})
-  check_c_source_compiles(
-    "
+  # GIF detection, gifdec isn't part of the imageio lib.
+  include(CMakePushCheckState)
+  set(WEBP_DEP_GIF_LIBRARIES)
+  set(WEBP_DEP_GIF_INCLUDE_DIRS)
+  find_package(GIF)
+  set(WEBP_HAVE_GIF ${GIF_FOUND})
+  if(GIF_FOUND)
+    # GIF find_package only locates the header and library, it doesn't fail
+    # compile tests when detecting the version, but falls back to 3 (as of at
+    # least cmake 3.7.2). Make sure the library links to avoid incorrect
+    # detection when cross compiling.
+    cmake_push_check_state()
+    set(CMAKE_REQUIRED_LIBRARIES ${GIF_LIBRARIES})
+    set(CMAKE_REQUIRED_INCLUDES ${GIF_INCLUDE_DIR})
+    check_c_source_compiles(
+      "
       #include <gif_lib.h>
       int main(void) {
         (void)DGifOpenFileHandle;
         return 0;
       }
       "
-    GIF_COMPILES)
-  cmake_pop_check_state()
-  if(GIF_COMPILES)
-    list(APPEND WEBP_DEP_GIF_LIBRARIES ${GIF_LIBRARIES})
-    list(APPEND WEBP_DEP_GIF_INCLUDE_DIRS ${GIF_INCLUDE_DIR})
-  else()
-    unset(GIF_FOUND)
+      GIF_COMPILES)
+    cmake_pop_check_state()
+    if(GIF_COMPILES)
+      list(APPEND WEBP_DEP_GIF_LIBRARIES ${GIF_LIBRARIES})
+      list(APPEND WEBP_DEP_GIF_INCLUDE_DIRS ${GIF_INCLUDE_DIR})
+    else()
+      unset(GIF_FOUND)
+    endif()
   endif()
 endif()