Added libpng as submodule (close #5)

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "ThirdParty/zlib"]
 	path = ThirdParty/zlib
 	url = https://github.com/DiligentGraphics/zlib
+[submodule "ThirdParty/libpng"]
+	path = ThirdParty/libpng
+	url = https://github.com/DiligentGraphics/libpng

Tests/DiligentToolsTest/CMakeLists.txt

@@ -11,6 +11,12 @@ if (NOT ARCHIVER_SUPPORTED)
     list(REMOVE_ITEM SOURCE ${CMAKE_CURRENT_SOURCE_DIR}/src/RenderStatePackager/RenderStatePackagerTest.cpp)
 endif()
 
+set_property(SOURCE src/PNGCodecTest.cpp
+APPEND PROPERTY INCLUDE_DIRECTORIES
+    "${CMAKE_CURRENT_SOURCE_DIR}/../../ThirdParty/libpng" # png_static target does not define any public include directories
+    "${CMAKE_CURRENT_BINARY_DIR}/../../ThirdParty/libpng" # pnglibconf.h is generated in the binary directory
+)
+
 set_source_files_properties(${ASSETS} PROPERTIES VS_TOOL_OVERRIDE "None")
 
 add_executable(DiligentToolsTest ${SOURCE} ${MAIN_CPP} ${INCLUDE} ${ASSETS})
@@ -25,7 +31,7 @@ PRIVATE
     Diligent-GraphicsEngine
     Diligent-RenderStateNotation
     Diligent-TestFramework
-    LibPng
+    PNG::PNG
     Diligent-JSON
 )
 

TextureLoader/CMakeLists.txt

@@ -34,6 +34,12 @@ set(SOURCE
 add_library(Diligent-TextureLoader STATIC ${SOURCE} ${INCLUDE} ${INTERFACE})
 set_common_target_properties(Diligent-TextureLoader)
 
+set_property(SOURCE src/PNGCodec.c src/Image.cpp
+APPEND PROPERTY INCLUDE_DIRECTORIES
+    "${CMAKE_CURRENT_SOURCE_DIR}/../ThirdParty/libpng" # png_static target does not define any public include directories
+    "${CMAKE_CURRENT_BINARY_DIR}/../ThirdParty/libpng" # pnglibconf.h is generated in the binary directory
+)
+
 target_include_directories(Diligent-TextureLoader
 PUBLIC
     interface

ThirdParty/CMakeLists.txt

@@ -21,9 +21,18 @@ if (NOT TARGET ZLIB::ZLIB)
 endif()
 
 if (NOT TARGET PNG::PNG)
-    add_subdirectory(lpng-1.6.17)
-    install(FILES lpng-1.6.17/LICENSE DESTINATION ${LICENSE_INSTALL_PATH} RENAME lpng-license.txt)
-    list(APPEND THIRD_PARTY_TARGETS LibPng)
+    set(PNG_BUILD_ZLIB ON CACHE BOOL "Use find_package(zlib) to find ZLib location")
+    set(PNG_SHARED OFF CACHE BOOL "Build shared version of libpng")
+    set(PNG_EXECUTABLES OFF CACHE BOOL "Build libpng executables")
+    set(PNG_TESTS OFF CACHE BOOL "Build libpng tests")
+    set(SKIP_INSTALL_ALL ON)
+    add_subdirectory(libpng)
+    set_target_properties(png_static genfiles PROPERTIES
+        FOLDER DiligentTools/ThirdParty/png
+    )
+    install(FILES libpng/LICENSE DESTINATION ${LICENSE_INSTALL_PATH} RENAME lpng-license.txt)
+    add_library(PNG::PNG ALIAS png_static)
+    list(APPEND THIRD_PARTY_TARGETS png_static)
 endif()