use conan.cmake, install libpng through conan

CMakeLists.txt

@@ -110,6 +110,19 @@ if(WIN32)
   set(WINDOWS True)
   set(PLATFORM_SHORTHAND win)
   message(STATUS "System: WINDOWS")
+
+  if (WIN_CHOCO)
+    if(NOT EXISTS "${CMAKE_BINARY_DIR}/conan.cmake")
+      message(STATUS "Downloading conan.cmake from https://github.com/conan-io/cmake-conan")
+      file(DOWNLOAD "https://github.com/conan-io/cmake-conan/raw/v0.14/conan.cmake"
+                    "${CMAKE_BINARY_DIR}/conan.cmake")
+
+      conan_add_remote(NAME bincrafters URL https://api.bintray.com/conan/bincrafters/public-conan)
+      conan_cmake_run(REQUIRES libpng/1.6.37@bincrafters/stable)
+
+    endif()
+  endif()
+
 endif(WIN32)
 
 # ----------------------------------------------------------------------------

cmake/external_deps.cmake

@@ -6,6 +6,10 @@ elseif(LINUX)
 elseif(ANDROID)
   find_library(PNG_LIBRARY png PATHS ${CMAKE_EXTERNAL_LIB} NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
 elseif(WINDOWS)
-  find_debug_and_optimized_library(PNG_LIBRARY "libpng/debug" "libpng" "libpng/release" "libpng")
+  if (WIN_CHOCO)
+  	set(PNG_LIBRARY CONAN_PKG::libpng)
+  else()
+	find_debug_and_optimized_library(PNG_LIBRARY "libpng/debug" "libpng" "libpng/release" "libpng")
+  endif()
 endif()