allow to force-disable webp from the command line

inspired by PR 377 by LebdevRI

build.sh

@@ -27,6 +27,7 @@ OPT_EXPERIMENTAL_IOP=-1
 OPT_GEO=-1
 OPT_LUA=-1
 OPT_OPENEXR=-1
+OPT_WEBP=-1
 
 # ---------------------------------------------------------------------------
 # Parse options
@@ -71,6 +72,9 @@ parse_feature()
 	openexr)
 		OPT_OPENEXR=$value
 		;;
+	webp)
+		OPT_WEBP=$value
+		;;
 	*)
 		echo "warning: unknown feature '$feature'"
 		;;
@@ -145,6 +149,7 @@ so that the cmake script autodetects features.
    --enable-geo
    --enable-lua
    --enable-openexr
+   --enable-webp
 
 Extra:
 -h --help                Print help message
@@ -218,6 +223,7 @@ cmake_boolean_option INSTALL_IOP_EXPERIMENTAL $OPT_EXPERIMENTAL_IOP
 cmake_boolean_option USE_GEO $OPT_GEO
 cmake_boolean_option USE_LUA $OPT_LUA
 cmake_boolean_option USE_OPENEXR $OPT_OPENEXR
+cmake_boolean_option USE_WEBP $OPT_WEBP
 
 # Some people might need this, but ignore if unset in environment
 CMAKE_PREFIX_PATH=${CMAKE_PREFIX_PATH:-}

src/CMakeLists.txt

@@ -164,12 +164,15 @@ if(USE_OPENEXR)
   endif(OPENEXR_FOUND)
 endif(USE_OPENEXR)
 
-find_package(WebP 0.3.0)
-if(WEBP_FOUND)
-  include_directories(${WebP_INCLUDE_DIRS})
-  list(APPEND LIBS ${WebP_LIBRARIES})
-  add_definitions(${WebP_DEFINITIONS})
-endif(WEBP_FOUND)
+if(USE_WEBP)
+   find_package(WebP 0.3.0)
+  if(WEBP_FOUND)
+    include_directories(${WebP_INCLUDE_DIRS})
+    list(APPEND LIBS ${WebP_LIBRARIES})
+    add_definitions(${WebP_DEFINITIONS})
+  endif(WEBP_FOUND)
+  else(USE_WEBP)
+endif(USE_WEBP)
 
 # Find all the libs that don't require extra parameters
 foreach(lib ${OUR_LIBS} LensFun GIO GThread GModule Cairo PangoCairo PThread Rsvg2 GDK-PixBuf LibXml2 Sqlite3 Exiv2 CURL PNG JPEG TIFF LCMS2)