Modified zlib search. Use system zlib on Android by default

3rdparty/CMakeLists.txt

-if(NOT ZLIB_FOUND)
-    add_subdirectory(zlib)
-endif()
 if(WITH_JASPER AND NOT JASPER_FOUND)
     add_subdirectory(libjasper)
 endif()

3rdparty/libpng/CMakeLists.txt

@@ -7,12 +7,7 @@ project(libpng)
 # List of C++ files:
 
 include_directories("${CMAKE_CURRENT_SOURCE_DIR}")
-
-if(ZLIB_FOUND)
-    include_directories(${ZLIB_INCLUDE_DIR})
-else()
-    include_directories("${CMAKE_CURRENT_SOURCE_DIR}/../zlib")
-endif()
+include_directories(${ZLIB_INCLUDE_DIR})
 
 file(GLOB lib_srcs *.c)
 file(GLOB lib_hdrs *.h)

3rdparty/zlib/CMakeLists.txt

@@ -37,11 +37,11 @@ if(MSVC)
 endif()
 
 configure_file("${CMAKE_CURRENT_SOURCE_DIR}/zconf.h.cmakein"
-               "${OpenCV_BINARY_DIR}/zconf.h" @ONLY)
-include_directories("${CMAKE_CURRENT_SOURCE_DIR}")
+               "${CMAKE_CURRENT_BINARY_DIR}/zconf.h" @ONLY)
+include_directories("${CMAKE_CURRENT_SOURCE_DIR}" "${CMAKE_CURRENT_BINARY_DIR}")
 
 set(ZLIB_PUBLIC_HDRS
-    "${OpenCV_BINARY_DIR}/zconf.h"
+    "${CMAKE_CURRENT_BINARY_DIR}/zconf.h"
     zlib.h
 )
 set(ZLIB_PRIVATE_HDRS
@@ -73,10 +73,8 @@ set(ZLIB_SRCS
     zutil.c
 )
 
-set(the_target "zlib")
-
-add_library(${the_target} STATIC ${ZLIB_SRCS} ${ZLIB_PUBLIC_HDRS} ${ZLIB_PRIVATE_HDRS})
-set_target_properties(${the_target} PROPERTIES DEFINE_SYMBOL ZLIB_DLL)
+add_library(${ZLIB_LIBRARY} STATIC ${ZLIB_SRCS} ${ZLIB_PUBLIC_HDRS} ${ZLIB_PRIVATE_HDRS})
+set_target_properties(${ZLIB_LIBRARY} PROPERTIES DEFINE_SYMBOL ZLIB_DLL)
 
 if(UNIX)
   if(CMAKE_COMPILER_IS_GNUCXX OR CV_ICC)
@@ -88,16 +86,16 @@ if(MSVC)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /wd4013")
 endif()
 
-set_target_properties(${the_target} PROPERTIES
-        OUTPUT_NAME "${the_target}"
+set_target_properties(${ZLIB_LIBRARY} PROPERTIES
+        OUTPUT_NAME ${ZLIB_LIBRARY}
         DEBUG_POSTFIX "${OPENCV_DEBUG_POSTFIX}"
         ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/3rdparty/${OPENCV_LIB_INSTALL_PATH}"
     )
 
 if(ENABLE_SOLUTION_FOLDERS)
-  set_target_properties(${the_target} PROPERTIES FOLDER "3rdparty")
+  set_target_properties(${ZLIB_LIBRARY} PROPERTIES FOLDER "3rdparty")
 endif()
 	
 if(NOT BUILD_SHARED_LIBS)
-  install(TARGETS ${the_target} ARCHIVE DESTINATION share/OpenCV/3rdparty/${OPENCV_LIB_INSTALL_PATH} COMPONENT main)
+  install(TARGETS ${ZLIB_LIBRARY} ARCHIVE DESTINATION share/OpenCV/3rdparty/${OPENCV_LIB_INSTALL_PATH} COMPONENT main)
 endif()

CMakeLists.txt

@@ -148,6 +148,9 @@ OCV_OPTION(BUILD_TESTS              "Build accuracy & regression tests"
 OCV_OPTION(BUILD_WITH_DEBUG_INFO    "Include debug info into debug libs"          ON )
 OCV_OPTION(BUILD_WITH_STATIC_CRT    "Enables use of staticaly linked CRT for staticaly linked OpenCV" ON IF MSVC )
 
+# 3rdparty libs
+OCV_OPTION(BUILD_ZLIB               "Build zlib from source instead of installed in the system"      WIN32 OR IOS )
+
 if(WIN32 OR ANDROID)
     set(OPENCV_BUILD_3RDPARTY_LIBS TRUE  CACHE INTERNAL "Build 3rd party libraries")
 else()
@@ -424,7 +427,6 @@ endif()
 if (UNIX OR WIN32)
     if(NOT OPENCV_BUILD_3RDPARTY_LIBS)
         message(STATUS "NOT OPENCV_BUILD_3RDPARTY_LIBS **************************************************")
-        include(FindZLIB)
         if(WITH_PNG)
             include(FindPNG)
             if(PNG_FOUND)
@@ -468,12 +470,26 @@ if(WITH_JASPER AND NOT JASPER_FOUND)
     set(JASPER_LIBRARIES libjasper)
 endif()
 
-if(NOT ZLIB_FOUND)
-    set(ZLIB_LIBRARY zlib)
+################### zlib - always required
+if(NOT BUILD_ZLIB)
+  if(ANDROID)
+    set(ZLIB_FOUND TRUE)
+    set(ZLIB_LIBRARY z)
+    set(ZLIB_INCLUDE_DIR "")
+  else()
+    include(FindZLIB)
+  endif()
+else()
+  set(ZLIB_FOUND FALSE)
 endif()
 
-#message(STATUS "Graphic libraries: ${PNG_LIBRARIES} ${JPEG_LIBRARIES} ${TIFF_LIBRARIES} ${JASPER_LIBRARIES}")
+if(NOT ZLIB_FOUND)
+  set(ZLIB_LIBRARY zlib)
+  add_subdirectory(3rdparty/zlib)
+  set(ZLIB_INCLUDE_DIR "${OpenCV_SOURCE_DIR}/3rdparty/zlib" "${${ZLIB_LIBRARY}_BINARY_DIR}")
+endif()
 
+################### OpenEXR
 if(WITH_OPENEXR)
   include(cmake/OpenCVFindOpenEXR.cmake)
 endif()
@@ -775,7 +791,7 @@ status("    OpenGL support:" HAVE_OPENGL THEN YES ELSE NO)
 # media
 status("")
 status("  Media I/O: ")
-status("    ZLib:"      ZLIB_FOUND                         THEN ${ZLIB_FOUND}   ELSE build)
+status("    ZLib:"      ZLIB_FOUND                         THEN "${ZLIB_FOUND} - ${ZLIB_LIBRARY}"   ELSE build)
 status("    JPEG:"      NOT WITH_JPEG OR JPEG_FOUND        THEN ${JPEG_FOUND}   ELSE build)
 status("    PNG:"       NOT WITH_PNG OR PNG_FOUND          THEN ${PNG_FOUND}    ELSE build)
 status("    TIFF:"      NOT WITH_TIFF OR TIFF_FOUND        THEN ${TIFF_FOUND}   ELSE build)

modules/core/CMakeLists.txt

 set(the_description "The Core Functionality")
 ocv_add_module(core ${ZLIB_LIBRARY})
-
-if(NOT ZLIB_FOUND)
-    set(ZLIB_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../../3rdparty/zlib")
-endif()
 ocv_module_include_directories(${ZLIB_INCLUDE_DIR})
 
 if(HAVE_CUDA)

modules/highgui/CMakeLists.txt

@@ -10,13 +10,8 @@ ocv_add_module(highgui opencv_imgproc OPTIONAL opencv_androidcamera)
 set(GRFMT_LIBS "")
 
 if(WITH_PNG OR WITH_TIFF OR WITH_OPENEXR)
-    if(ZLIB_FOUND)
-        include_directories(${ZLIB_INCLUDE_DIR})
-        set(GRFMT_LIBS ${GRFMT_LIBS} ${ZLIB_LIBRARIES})
-    else()
-        include_directories("${CMAKE_CURRENT_SOURCE_DIR}/../../3rdparty/zlib")
-        set(GRFMT_LIBS ${GRFMT_LIBS} zlib)
-    endif()
+  include_directories(${ZLIB_INCLUDE_DIR})
+  set(GRFMT_LIBS ${GRFMT_LIBS} ${ZLIB_LIBRARY})
 endif()
 
 if(WITH_JPEG)