Merge pull request #8186 from Kronopath:patch-1

CMakeLists.txt

@@ -25,19 +25,21 @@ endif()
 # Following block can broke build in case of cross-compilng
 # but CMAKE_CROSSCOMPILING variable will be set only on project(OpenCV) command
 # so we will try to detect crosscompiling by presense of CMAKE_TOOLCHAIN_FILE
-if(NOT CMAKE_TOOLCHAIN_FILE)
-  # it _must_ go before project(OpenCV) in order to work
-  if(WIN32)
+if(NOT DEFINED CMAKE_INSTALL_PREFIX)
+  if(NOT CMAKE_TOOLCHAIN_FILE)
+    # it _must_ go before project(OpenCV) in order to work
+    if(WIN32)
+      set(CMAKE_INSTALL_PREFIX "${CMAKE_BINARY_DIR}/install" CACHE PATH "Installation Directory")
+    else()
+      set(CMAKE_INSTALL_PREFIX "/usr/local" CACHE PATH "Installation Directory")
+    endif()
+  else(NOT CMAKE_TOOLCHAIN_FILE)
+    #Android: set output folder to ${CMAKE_BINARY_DIR}
+    set( LIBRARY_OUTPUT_PATH_ROOT ${CMAKE_BINARY_DIR} CACHE PATH "root for library output, set this to change where android libs are compiled to" )
+    # any crosscompiling
     set(CMAKE_INSTALL_PREFIX "${CMAKE_BINARY_DIR}/install" CACHE PATH "Installation Directory")
-  else()
-    set(CMAKE_INSTALL_PREFIX "/usr/local" CACHE PATH "Installation Directory")
-  endif()
-else(NOT CMAKE_TOOLCHAIN_FILE)
-  #Android: set output folder to ${CMAKE_BINARY_DIR}
-  set( LIBRARY_OUTPUT_PATH_ROOT ${CMAKE_BINARY_DIR} CACHE PATH "root for library output, set this to change where android libs are compiled to" )
-  # any crosscompiling
-  set(CMAKE_INSTALL_PREFIX "${CMAKE_BINARY_DIR}/install" CACHE PATH "Installation Directory")
-endif(NOT CMAKE_TOOLCHAIN_FILE)
+  endif(NOT CMAKE_TOOLCHAIN_FILE)
+endif()
 
 if(CMAKE_SYSTEM_NAME MATCHES WindowsPhone OR CMAKE_SYSTEM_NAME MATCHES WindowsStore)
   set(WINRT TRUE)