Enable by default PIC for the static library build

Can be disabled via AV_ENABLE_STATIC_PIC=Off

Author: h4tr3d

CMakeLists.txt

@@ -14,6 +14,7 @@ set(CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake ${CMAKE_MODULE_PATH})
 set(FFMPEG_PKG_CONFIG_SUFFIX "" CACHE STRING "This suffix uses for FFmpeg component names searches by pkg-config")
 set(AV_ENABLE_STATIC On CACHE BOOL "Enable static library build (On)")
 set(AV_ENABLE_SHARED On CACHE BOOL "Enable shared library build (On)")
+set(AV_ENABLE_STATIC_PIC On CACHE BOOL "Enable Position Independent Code build for the statis library")
 set(AV_BUILD_EXAMPLES On CACHE BOOL "Build example applications (On)")
 set(AV_BUILD_TESTS On CACHE BOOL "Build tests (On)")
 option(AV_DISABLE_AVFORMAT "Disable libavformat usage. Also turns off: AVFILTER, AVDEVICE" Off)

src/CMakeLists.txt

@@ -41,6 +41,12 @@ foreach(TARGET ${AV_TARGETS})
 
     add_library(${TARGET} ${TYPE} ${AV_SOURCES} ${AV_HEADERS})
 
+    # allow use static library to build shared one
+    if (AV_ENABLE_STATIC_PIC AND ${TYPE} MATCHES "STATIC")
+        message(STATUS "Enable POSITION_INDEPENDENT_CODE (-fPIC) build for static library")
+        set_target_properties(${TARGET} PROPERTIES POSITION_INDEPENDENT_CODE ON)
+    endif()
+
     target_compile_options(${TARGET} PRIVATE ${AVCPP_WARNING_OPTIONS})
     target_compile_definitions(${TARGET} PUBLIC __STDC_CONSTANT_MACROS)
     target_link_libraries(${TARGET} PRIVATE Threads::Threads PUBLIC FFmpeg::FFmpeg)