Shared library support for C API

.gitignore

@@ -3,6 +3,7 @@ build/
 # VS project and working files
 *.vcxproj.user
 .vs/
+.vscode/
 Debug/
 Release/
 x64/

CMakeLists.txt

@@ -20,7 +20,8 @@ endif()
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
-option(BASISU_STATIC "static linking" FALSE)
+option(BASISU_STATIC "Link runtime libraries statically" FALSE)
+option(BASISU_SHARED "Build basis-universal as a shared library" FALSE)
 option(BASISU_SAN "sanitize" FALSE)
 option(BASISU_EXAMPLES "build examples" TRUE)
 option(BASISU_WASM_THREADING "Enable WASI threading support" OFF)
@@ -84,9 +85,18 @@ if (BASISU_BUILD_WASM)
 
     # WASM cannot use sanitizers
     set(BASISU_SAN OFF CACHE BOOL "" FORCE)
+
+    # WASM cannot link as a shared object
+    set(BASISU_SHARED OFF CACHE BOOL "" FORCE)
+endif()
+
+if (BASISU_BUILD_PYTHON)
+    # Dynamic linking is not supported on Python builds
+    set(BASISU_SHARED OFF CACHE BOOL "" FORCE)
 endif()
 
 message("Initial CMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}")
+message("Initial BASISU_SHARED=${BASISU_SHARED}")
 message("Initial BASISU_BUILD_X64=${BASISU_BUILD_X64}")
 message("Initial BASISU_BUILD_WASM=${BASISU_BUILD_WASM}")
 message("Initial BASISU_WASM_THREADING=${BASISU_WASM_THREADING}")
@@ -248,6 +258,8 @@ set(ENCODER_LIB_SRC_LIST
     encoder/basisu_astc_ldr_common.cpp
     encoder/basisu_astc_ldr_encode.cpp
     encoder/basisu_tinyexr.cpp
+    encoder/basisu_wasm_api.cpp
+    encoder/basisu_wasm_transcoder_api.cpp
     transcoder/basisu_transcoder.cpp
     encoder/basisu_astc_hdr_6x6_enc.h
     encoder/basisu_astc_hdr_common.h
@@ -305,19 +317,42 @@ if (BASISU_ZSTD)
     set(ENCODER_LIB_SRC_LIST ${ENCODER_LIB_SRC_LIST} zstd/zstd.c)
 endif()
 
-# Create the static library
-add_library(basisu_encoder STATIC ${ENCODER_LIB_SRC_LIST})
+# Create the library
+
+if (BASISU_SHARED)
+    add_library(basisu_encoder SHARED ${ENCODER_LIB_SRC_LIST})
+
+    set_target_properties(basisu_encoder PROPERTIES
+        CXX_VISIBILITY_PRESET hidden
+        VISIBILITY_INLINES_HIDDEN 1
+        VERSION   2.10
+        SOVERSION 2
+    )
+
+    if (MSVC)
+        set_target_properties(basisu_encoder PROPERTIES
+            RUNTIME_OUTPUT_DIRECTORY_DEBUG          ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}
+            RUNTIME_OUTPUT_DIRECTORY_RELEASE        ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}
+            RUNTIME_OUTPUT_DIRECTORY_RELWITHDEBINFO ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}
+            RUNTIME_OUTPUT_DIRECTORY_MINSIZEREL     ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}
+        )
+    endif()
+
+    target_compile_definitions(basisu_encoder PUBLIC BASISU_SHARED)
+else()
+    add_library(basisu_encoder STATIC ${ENCODER_LIB_SRC_LIST})
+endif()
 
-# Create the basisu executable and link against the static library
+# Create the basisu executable and link against the library
 add_executable(basisu basisu_tool.cpp)
 target_link_libraries(basisu PRIVATE basisu_encoder)
 
-# Create the new example executable and link against the static library
+# Create the new example executable and link against the library
 if(BASISU_EXAMPLES)
     add_executable(example example/example.cpp)
     target_link_libraries(example PRIVATE basisu_encoder)
 
-    add_executable(example_capi example_capi/example_capi.c encoder/basisu_wasm_api.cpp encoder/basisu_wasm_transcoder_api.cpp)
+    add_executable(example_capi example_capi/example_capi.c)
     target_link_libraries(example_capi PRIVATE basisu_encoder)
 
     add_executable(example_transcoding example_transcoding/example_transcoding.cpp example_transcoding/utils.cpp zstd/zstddeclib.c transcoder/basisu_transcoder.cpp)
@@ -355,7 +390,7 @@ if (BASISU_BUILD_WASM)
 
     endif()
 
-    # 256 MB initial, 3.5 GB max � safe defaults for BasisU
+    # 256 MB initial, 3.5 GB max — safe defaults for BasisU
     target_link_options(basisu PRIVATE
         -Wl,--initial-memory=268435456
         -Wl,--max-memory=3758096384
@@ -592,7 +627,6 @@ if (BASISU_BUILD_WASM)
     endif()
 
     add_executable(${BASISU_TRANSCODER_WASM_OUTPUT_NAME} 
-        ${CMAKE_CURRENT_SOURCE_DIR}/encoder/basisu_wasm_transcoder_api.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/transcoder/basisu_transcoder.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/zstd/zstddeclib.c)
 
@@ -655,7 +689,7 @@ if (BASISU_BUILD_PYTHON AND NOT BASISU_BUILD_WASM)
 
     pybind11_add_module(basisu_transcoder_python
         python/basisu_transcoder_pybind11.cpp
-        encoder/basisu_wasm_transcoder_api.cpp  
+        encoder/basisu_wasm_transcoder_api.cpp
         transcoder/basisu_transcoder.cpp
         zstd/zstddeclib.c
     )

encoder/basisu_wasm_api_common.h

@@ -1,6 +1,7 @@
 // File: basisu_wasm_api_common.h
 #pragma once
 #include "stdint.h"
+#include "../transcoder/basisu_config.h"
 
 #if defined(__wasm__)
 	#if defined(__cplusplus)
@@ -9,9 +10,9 @@
 		#define BU_WASM_EXPORT(name) __attribute__((export_name(name)))
 	#endif
 #elif defined(__cplusplus)
-	#define BU_WASM_EXPORT(name) extern "C"
+	#define BU_WASM_EXPORT(name) extern "C" BASISU_API
 #else
-	#define BU_WASM_EXPORT(name)
+	#define BU_WASM_EXPORT(name) BASISU_API
 #endif
 
 // wasm_bool_t is an alias for uint32_t

transcoder/basisu_config.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#ifndef BASISU_SHARED
+    #define BASISU_API
+#elif defined(_WIN32)
+    #ifdef basisu_encoder_EXPORTS
+        #define BASISU_API __declspec(dllexport)
+    #else
+        #define BASISU_API __declspec(dllimport)
+    #endif
+#else
+    #ifdef basisu_encoder_EXPORTS
+        #define BASISU_API __attribute__((visibility("default")))
+    #else
+        #define BASISU_API
+    #endif
+#endif