Initial C API for FFI

CMakeLists.txt

@@ -486,6 +486,11 @@ list(
     "${draco_src_root}/javascript/emscripten/draco_animation_encoder_glue_wrapper.cc"
   )
 
+list(
+  APPEND draco_c_api_dec_sources
+    "${draco_src_root}/c_api/c_api_decoder.cc"
+  )
+
 list(APPEND draco_unity_plug_sources
             "${draco_src_root}/unity/draco_unity_plugin.cc"
             "${draco_src_root}/unity/draco_unity_plugin.h")
@@ -773,6 +778,16 @@ else()
                     ${draco_defines}
                     INCLUDES
                     ${draco_include_paths})
+  draco_add_library(NAME
+                    draco_c_api_dec
+                    TYPE 
+                    OBJECT
+                    SOURCES
+                    ${draco_c_api_dec_sources}
+                    DEFINES
+                    ${draco_defines}
+                    INCLUDES
+                    ${draco_include_paths})
 
   set(draco_object_library_deps
       draco_attributes
@@ -803,6 +818,10 @@ else()
       draco_points_dec
       draco_points_enc)
 
+  list(APPEND draco_c_api_object_library_deps
+              ${draco_object_library_deps}
+              draco_c_api_dec)
+
   # Library targets that consume the object collections.
   if(MSVC OR WIN32)
     # In order to produce a DLL and import library the Windows tools require
@@ -829,7 +848,28 @@ else()
                       ${draco_include_paths}
                       OBJLIB_DEPS
                       ${draco_object_library_deps})
-
+    if(BUILD_SHARED_LIBS)
+      set_target_properties(draco PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
+    endif()
+    if(DRACO_C_API)
+      draco_add_library(NAME
+                        cdraco
+                        OUTPUT_NAME
+                        cdraco
+                        TYPE
+                        ${draco_lib_type}
+                        DEFINES
+                        ${draco_defines}
+                        INCLUDES
+                        ${draco_include_paths}
+                        PUBLIC_INCLUDES
+                        ${draco_c_public_api_include_paths}
+                        OBJLIB_DEPS
+                        ${draco_c_api_object_library_deps})
+      if(BUILD_SHARED_LIBS)
+        set_target_properties(cdraco PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS FALSE)
+      endif()
+    endif()
   else()
     draco_add_library(NAME
                       draco_static
@@ -843,7 +883,22 @@ else()
                       ${draco_include_paths}
                       OBJLIB_DEPS
                       ${draco_object_library_deps})
-
+    if(DRACO_C_API)
+      draco_add_library(NAME
+                        cdraco_static
+                        OUTPUT_NAME
+                        cdraco
+                        TYPE
+                        STATIC
+                        DEFINES
+                        ${draco_defines}
+                        INCLUDES
+                        ${draco_include_paths}
+                        PUBLIC_INCLUDES
+                        ${draco_c_public_api_include_paths}
+                        OBJLIB_DEPS
+                        ${draco_c_api_object_library_deps})
+    endif()
     if(BUILD_SHARED_LIBS)
       draco_add_library(NAME
                         draco_shared
@@ -859,6 +914,27 @@ else()
                         ${draco_include_paths}
                         LIB_DEPS
                         draco_static)
+      if(DRACO_C_API)
+        draco_add_library(NAME
+                          cdraco_shared
+                          SOURCES
+                          "${draco_src_root}/core/draco_version.h"
+                          OUTPUT_NAME
+                          cdraco
+                          TYPE
+                          SHARED
+                          DEFINES
+                          ${draco_defines}
+                          INCLUDES
+                          ${draco_include_paths}
+                          PUBLIC_INCLUDES
+                          ${draco_c_public_api_include_paths}
+                          OBJLIB_DEPS
+                          cdraco_static)
+        set_target_properties(cdraco_static PROPERTIES C_VISIBILITY_PRESET hidden)
+        set_target_properties(cdraco_static PROPERTIES CXX_VISIBILITY_PRESET hidden)
+        set_target_properties(cdraco_static PROPERTIES VISIBILITY_INLINES_HIDDEN ON)
+      endif()
     endif()
   endif()
 

cmake/draco_build_definitions.cmake

@@ -41,6 +41,8 @@ macro(draco_set_build_definitions)
   list(APPEND draco_include_paths "${draco_root}" "${draco_root}/src"
               "${draco_build}")
 
+  list(APPEND draco_c_public_api_include_paths "${draco_root}/src/draco/c_api")
+
   if(DRACO_ABSL)
     list(APPEND draco_include_path "${draco_root}/third_party/abseil-cpp")
   endif()
@@ -59,10 +61,6 @@ macro(draco_set_build_definitions)
 
   if(MSVC OR WIN32)
     list(APPEND draco_defines "_CRT_SECURE_NO_DEPRECATE=1" "NOMINMAX=1")
-
-    if(BUILD_SHARED_LIBS)
-      set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
-    endif()
   endif()
 
   if(ANDROID)

cmake/draco_options.cmake

@@ -64,6 +64,8 @@ macro(draco_set_default_options)
                "Enable attribute deduping." VALUE OFF)
   draco_option(NAME DRACO_TESTS HELPSTRING "Enables tests." VALUE OFF)
   draco_option(NAME DRACO_WASM HELPSTRING "Enables WASM support." VALUE OFF)
+  draco_option(NAME DRACO_C_API HELPSTRING
+               "Build C wrapper." VALUE OFF)
   draco_option(NAME DRACO_UNITY_PLUGIN HELPSTRING
                "Build plugin library for Unity." VALUE OFF)
   draco_option(NAME DRACO_ANIMATION_ENCODING HELPSTRING "Enable animation."
@@ -170,6 +172,10 @@ macro(draco_set_optional_features)
     set(CMAKE_POSITION_INDEPENDENT_CODE ON)
   endif()
 
+  if(DRACO_C_API)
+    draco_enable_feature(FEATURE "DRACO_C_API_SUPPORTED")
+  endif()
+
 endmacro()
 
 # Macro that handles tracking of Draco preprocessor symbols for the purpose of

cmake/draco_tests.cmake

@@ -52,7 +52,17 @@ list(
     "${draco_src_root}/metadata/metadata_encoder_test.cc"
     "${draco_src_root}/metadata/metadata_test.cc"
     "${draco_src_root}/point_cloud/point_cloud_builder_test.cc"
-    "${draco_src_root}/point_cloud/point_cloud_test.cc")
+    "${draco_src_root}/point_cloud/point_cloud_test.cc"
+    "${draco_src_root}/c_api/c_api_test.cc")
+
+list(APPEND draco_test_lib_deps
+            draco_static
+            draco_gtest
+            draco_gtest_main)
+
+if(DRACO_C_API)
+  list(APPEND draco_test_lib_deps cdraco_static)
+endif()
 
 list(APPEND draco_gtest_all
             "${draco_root}/../googletest/googletest/src/gtest-all.cc")
@@ -112,9 +122,7 @@ macro(draco_setup_test_targets)
                          INCLUDES
                          ${draco_test_include_paths}
                          LIB_DEPS
-                         draco_static
-                         draco_gtest
-                         draco_gtest_main)
+                         ${draco_test_lib_deps})
 
     draco_add_executable(NAME
                          draco_factory_tests
@@ -126,8 +134,6 @@ macro(draco_setup_test_targets)
                          INCLUDES
                          ${draco_test_include_paths}
                          LIB_DEPS
-                         draco_static
-                         draco_gtest
-                         draco_gtest_main)
+                         ${draco_test_lib_deps})
   endif()
 endmacro()

src/draco/c_api/c_api.h

@@ -0,0 +1,101 @@
+// Copyright 2020 The Draco Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+#ifndef DRACO_C_API_H_
+#define DRACO_C_API_H_
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef _WIN32
+# if defined(DRACO_BUILDING_DLL)
+#  define EXPORT_API __declspec(dllexport)
+# elif !defined(DRACO_STATIC)
+#  define EXPORT_API __declspec(dllimport)
+# else
+#  define EXPORT_API
+# endif
+#elif __GNUC__ >= 4 || defined(__clang__)
+# define EXPORT_API __attribute__((visibility ("default")))
+#else
+ #define EXPORT_API
+#endif  // defined(_WIN32)
+
+typedef const char* draco_string; // NULL terminated
+
+// draco::Status
+
+typedef struct draco_status draco_status;
+
+EXPORT_API void dracoStatusRelease(draco_status *status);
+
+EXPORT_API int dracoStatusCode(const draco_status *status);
+
+EXPORT_API bool dracoStatusOk(const draco_status *status);
+
+// Returns the status message.
+// The memory backing memory is valid meanwhile status is not released.
+EXPORT_API draco_string dracoStatusErrorMsg(const draco_status *status);
+
+// draco::Mesh
+
+typedef uint32_t draco_face[3];
+typedef struct draco_mesh draco_mesh;
+
+EXPORT_API draco_mesh* dracoNewMesh();
+
+EXPORT_API void dracoMeshRelease(draco_mesh *mesh);
+
+EXPORT_API uint32_t dracoMeshNumFaces(const draco_mesh *mesh);
+
+EXPORT_API uint32_t dracoMeshNumPoints(const draco_mesh *mesh);
+
+// Queries an array of 3*face_count elements containing the triangle indices.
+// out_values must be allocated to contain at least 3*face_count uint16_t elements.
+// out_size must be exactly 3*face_count*sizeof(uint16_t), else out_values
+// won´t be filled and returns false.
+EXPORT_API bool dracoMeshGetTrianglesUint16(const draco_mesh *mesh,
+                                            const size_t out_size,
+                                            uint16_t *out_values);
+
+// Queries an array of 3*face_count elements containing the triangle indices.
+// out_values must be allocated to contain at least 3*face_count uint32_t elements.
+// out_size must be exactly 3*face_count*sizeof(uint32_t), else out_values
+// won´t be filled and returns false.
+EXPORT_API bool dracoMeshGetTrianglesUint32(const draco_mesh *mesh,
+                                            const size_t out_size,
+                                            uint32_t *out_values);
+
+// draco::Decoder
+
+typedef struct draco_decoder draco_decoder;
+
+EXPORT_API draco_decoder* dracoNewDecoder();
+
+EXPORT_API void dracoDecoderRelease(draco_decoder *decoder);
+
+EXPORT_API draco_status* dracoDecoderArrayToMesh(draco_decoder *decoder, 
+                                                 const char *data, 
+                                                 size_t data_size,
+                                                 draco_mesh *out_mesh);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // DRACO_C_API_H_