optional_depends "zlib"   "--disable-localzlib"  "--enable-localzlib" "use system zlib"
optional_depends "%JPEG"  "--disable-localjpeg"  "--enable-localjpeg" "use system jpeg"
optional_depends "libpng" "--disable-localpng"   "--enable-localpng"  "use system png"
optional_depends "cairo"  "--enable-cairo"       "--disable-cairo"    "for cairo support"

