[Android] Wrote a native activity acting as a bootstrap

A current limitation prevents one library from depending on shared libraries.
As we have legal issues here (LGPL wants us to use shared libs of OpenAL-Soft and libsndfile), we're forced to use this homemade native activity which will manually load our shared libraries.

CMakeLists.txt

@@ -88,6 +88,11 @@ if(ANDROID)
 
     # we install libs in a subdirectory named after the ABI (lib/mips/*.so)
     set(LIB_SUFFIX "/${ANDROID_ABI}")
+
+    # this is a workaround to compile sfml-activity without stlport_shared as dependency
+    # we save the original compilation command line to restore it later in Macro.cmake
+    set(CMAKE_CXX_CREATE_SHARED_LIBRARY_WITH_STLPORT ${CMAKE_CXX_CREATE_SHARED_LIBRARY})
+    set(CMAKE_CXX_CREATE_SHARED_LIBRARY_WITHOUT_STLPORT "<CMAKE_CXX_COMPILER> <CMAKE_SHARED_LIBRARY_CXX_FLAGS> <LANGUAGE_COMPILE_FLAGS> <LINK_FLAGS> <CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS> <SONAME_FLAG><TARGET_SONAME> -o <TARGET> <OBJECTS> <LINK_LIBRARIES>")
 endif()
 
 # define SFML_STATIC if the build type is not set to 'shared'

cmake/Macros.cmake

@@ -97,6 +97,18 @@ macro(sfml_add_library target)
         set_target_properties(${target} PROPERTIES XCODE_ATTRIBUTE_CLANG_ENABLE_OBJC_ARC YES)
     endif()
 
+    # sfml-activity library is our bootstrap activity and must not depend on stlport_shared
+    # (otherwise Android will fail to load it)
+    if (ANDROID)
+        if (${target} MATCHES "sfml-activity")
+            set_target_properties(${target} PROPERTIES COMPILE_FLAGS -fpermissive)
+            set_target_properties(${target} PROPERTIES LINK_FLAGS "-landroid -llog")
+            set(CMAKE_CXX_CREATE_SHARED_LIBRARY ${CMAKE_CXX_CREATE_SHARED_LIBRARY_WITHOUT_STLPORT})
+        else()
+            set(CMAKE_CXX_CREATE_SHARED_LIBRARY ${CMAKE_CXX_CREATE_SHARED_LIBRARY_WITH_STLPORT})
+        endif()
+    endif()
+
     # link the target to its external dependencies
     if(THIS_EXTERNAL_LIBS)
         target_link_libraries(${target} ${THIS_EXTERNAL_LIBS})

extlibs/android/extlibs/Android.mk

@@ -16,32 +16,24 @@ include $(CLEAR_VARS)
 LOCAL_MODULE := ogg
 LOCAL_SRC_FILES := lib/$(TARGET_ARCH_ABI)/libogg.so
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
-TARGET_ARCH_ABI := armeabi armeabi-v7a x86
-
 include $(PREBUILT_SHARED_LIBRARY)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := flac
 LOCAL_SRC_FILES := lib/$(TARGET_ARCH_ABI)/libFLAC.so
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
-TARGET_ARCH_ABI := armeabi armeabi-v7a x86
-
 include $(PREBUILT_SHARED_LIBRARY)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := vorbis
 LOCAL_SRC_FILES := lib/$(TARGET_ARCH_ABI)/libvorbis.so
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
-TARGET_ARCH_ABI := armeabi armeabi-v7a x86
-
 include $(PREBUILT_SHARED_LIBRARY)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := vorbisenc
 LOCAL_SRC_FILES := lib/$(TARGET_ARCH_ABI)/libvorbisenc.so
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
-TARGET_ARCH_ABI := armeabi armeabi-v7a x86
-
 include $(PREBUILT_SHARED_LIBRARY)
 
 include $(CLEAR_VARS)
@@ -49,8 +41,6 @@ LOCAL_MODULE := sndfile
 LOCAL_SRC_FILES := lib/$(TARGET_ARCH_ABI)/libsndfile.so
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_SHARED_LIBRARIES := ogg flac vorbis vorbisenc
-TARGET_ARCH_ABI := armeabi armeabi-v7a x86
-
 include $(PREBUILT_SHARED_LIBRARY)
 
 include $(CLEAR_VARS)
@@ -58,6 +48,4 @@ LOCAL_MODULE := openal
 LOCAL_SRC_FILES := lib/$(TARGET_ARCH_ABI)/libopenal.so
 LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_SHARED_LIBRARIES := ogg flac vorbis vorbisenc
-TARGET_ARCH_ABI := armeabi armeabi-v7a x86
-
 include $(PREBUILT_SHARED_LIBRARY)

src/SFML/Android.mk

@@ -55,4 +55,11 @@ LOCAL_SHARED_LIBRARIES := sfml-system sfml-window
 
 include $(PREBUILT_STATIC_LIBRARY)
 
+include $(CLEAR_VARS)
+LOCAL_MODULE := sfml-activity
+LOCAL_SRC_FILES := lib/$(TARGET_ARCH_ABI)/libsfml-activity.so
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/include
+
+include $(PREBUILT_SHARED_LIBRARY)
+
 $(call import-module,sfml/extlibs)

src/SFML/Main/CMakeLists.txt

@@ -28,3 +28,10 @@ set_target_properties(sfml-main PROPERTIES FOLDER "SFML")
 
 # setup the install rule
 install(TARGETS sfml-main ARCHIVE DESTINATION lib${LIB_SUFFIX} COMPONENT devel)
+
+# because of a current limitation on Android (which prevents one library
+# from depending on shared libraries), we need a boostrap activity which
+# will load our shared libraries manually
+if(ANDROID)
+	sfml_add_library(sfml-activity SOURCES ${PROJECT_SOURCE_DIR}/src/SFML/Main/SFMLActivity.cpp)
+endif()

src/SFML/Main/SFMLActivity.cpp

@@ -0,0 +1,166 @@
+////////////////////////////////////////////////////////////
+//
+// SFML - Simple and Fast Multimedia Library
+// Copyright (C) 2013 Jonathan De Wachter (dewachter.jonathan@gmail.com)
+//
+// This software is provided 'as-is', without any express or implied warranty.
+// In no event will the authors be held liable for any damages arising from the use of this software.
+//
+// Permission is granted to anyone to use this software for any purpose,
+// including commercial applications, and to alter it and redistribute it freely,
+// subject to the following restrictions:
+//
+// 1. The origin of this software must not be misrepresented;
+//    you must not claim that you wrote the original software.
+//    If you use this software in a product, an acknowledgment
+//    in the product documentation would be appreciated but is not required.
+//
+// 2. Altered source versions must be plainly marked as such,
+//    and must not be misrepresented as being the original software.
+//
+// 3. This notice may not be removed or altered from any source distribution.
+//
+////////////////////////////////////////////////////////////
+
+#include <android/native_activity.h>
+#include <android/log.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <jni.h>
+
+#define LOGE(...) ((void)__android_log_print(ANDROID_LOG_INFO, "sfml-activity", __VA_ARGS__))
+
+void* loadLibrary(const char* libraryName, JNIEnv* lJNIEnv, jobject& ObjectActivityInfo)
+{
+    // Find out the absolute path of the library
+    jclass ClassActivityInfo = lJNIEnv->FindClass("android/content/pm/ActivityInfo");
+    jfieldID FieldApplicationInfo = lJNIEnv->GetFieldID(ClassActivityInfo, "applicationInfo", "Landroid/content/pm/ApplicationInfo;");
+    jobject ObjectApplicationInfo = lJNIEnv->GetObjectField(ObjectActivityInfo, FieldApplicationInfo);
+
+    jclass ClassApplicationInfo = lJNIEnv->FindClass("android/content/pm/ApplicationInfo");
+    jfieldID FieldNativeLibraryDir = lJNIEnv->GetFieldID(ClassApplicationInfo, "nativeLibraryDir", "Ljava/lang/String;");
+
+    jobject ObjectDirPath = lJNIEnv->GetObjectField(ObjectApplicationInfo, FieldNativeLibraryDir);
+
+    jclass ClassSystem = lJNIEnv->FindClass("java/lang/System");
+    jmethodID StaticMethodMapLibraryName = lJNIEnv->GetStaticMethodID(ClassSystem, "mapLibraryName", "(Ljava/lang/String;)Ljava/lang/String;");
+
+    jstring LibNameObject = lJNIEnv->NewStringUTF(libraryName);
+    jobject ObjectName = lJNIEnv->CallStaticObjectMethod(ClassSystem, StaticMethodMapLibraryName, LibNameObject);
+
+    jclass ClassFile = lJNIEnv->FindClass("java/io/File");
+    jmethodID FileConstructor = lJNIEnv->GetMethodID(ClassFile, "<init>", "(Ljava/lang/String;Ljava/lang/String;)V");
+    jobject ObjectFile = lJNIEnv->NewObject(ClassFile, FileConstructor, ObjectDirPath, ObjectName);
+
+    // Get the library absolute path and convert it
+    jmethodID MethodGetPath = lJNIEnv->GetMethodID(ClassFile, "getPath", "()Ljava/lang/String;");
+    jstring javaLibraryPath = static_cast<jstring>(lJNIEnv->CallObjectMethod(ObjectFile, MethodGetPath));
+    const char* libraryPath = lJNIEnv->GetStringUTFChars(javaLibraryPath, NULL);
+
+    // Manually load the library
+    void * handle = dlopen(libraryPath, RTLD_NOW | RTLD_GLOBAL);
+    if (!handle)
+    {
+        LOGE("dlopen(\"%s\"): %s", libraryPath, dlerror());
+        exit(1);
+    }
+
+    // Release the Java string
+    lJNIEnv->ReleaseStringUTFChars(THESTRING, pathStr);
+
+    return handle;
+}
+
+void ANativeActivity_onCreate(ANativeActivity* activity, void* savedState, size_t savedStateSize)
+{
+    // Before we can load a library, we need to find out its location. As
+    // we're powerless here in C/C++, we need the JNI interface to communicate
+    // with the attached Java virtual machine and perform some Java calls in
+    // order to retrieve the absolute path of our libraries.
+    //
+    // Here's the snippet of Java code it performs:
+    // --------------------------------------------
+    // ai = getPackageManager().getActivityInfo(getIntent().getComponent(), PackageManager.GET_META_DATA);
+    // File libraryFile = new File(ai.applicationInfo.nativeLibraryDir, System.mapLibraryName(libname));
+    // String path = libraryFile.getPath();
+    //
+    // With libname being the library name such as "jpeg".
+
+    // Initialize JNI
+    jint lResult;
+    jint lFlags = 0;
+
+    JavaVM* lJavaVM = activity->vm;
+    JNIEnv* lJNIEnv = activity->env;
+
+    JavaVMAttachArgs lJavaVMAttachArgs;
+    lJavaVMAttachArgs.version = JNI_VERSION_1_6;
+    lJavaVMAttachArgs.name = "NativeThread";
+    lJavaVMAttachArgs.group = NULL;
+
+    // Attach the current thread to the JAva virtual machine
+    lResult=lJavaVM->AttachCurrentThread(&lJNIEnv, &lJavaVMAttachArgs);
+
+    if (lResult == JNI_ERR) {
+        LOG("Couldn't attach the current thread to the Java virtual machine");
+        exit(1);
+    }
+
+    // Retrieve the NativeActivity
+    jobject ObjectNativeActivity = activity->clazz;
+    jclass ClassNativeActivity = lJNIEnv->GetObjectClass(ObjectNativeActivity);
+
+    // Retrieve the ActivityInfo
+    jmethodID MethodGetPackageManager = lJNIEnv->GetMethodID(ClassNativeActivity, "getPackageManager", "()Landroid/content/pm/PackageManager;");
+    jobject ObjectPackageManager = lJNIEnv->CallObjectMethod(ObjectNativeActivity, MethodGetPackageManager);
+
+    jmethodID MethodGetIndent = lJNIEnv->GetMethodID(ClassNativeActivity, "getIntent", "()Landroid/content/Intent;");
+    jobject ObjectIntent = lJNIEnv->CallObjectMethod(ObjectNativeActivity, MethodGetIndent);
+
+    jclass ClassIntent = lJNIEnv->FindClass("android/content/Intent");
+    jmethodID MethodGetComponent = lJNIEnv->GetMethodID(ClassIntent, "getComponent", "()Landroid/content/ComponentName;");
+
+    jobject ObjectComponentName = lJNIEnv->CallObjectMethod(ObjectIntent, MethodGetComponent);
+
+    jclass ClassPackageManager = lJNIEnv->FindClass("android/content/pm/PackageManager");
+
+    //jfieldID FieldGET_META_DATA = lJNIEnv->GetStaticFieldID(ClassPackageManager, "GET_META_DATA", "L");
+    //jobject GET_META_DATA = lJNIEnv->GetStaticObjectField(ClassPackageManager, FieldGET_META_DATA);
+    // getActivityInfo(getIntent().getComponent(), PackageManager.GET_META_DATA) -> ActivityInfo object
+    jmethodID MethodGetActivityInfo = lJNIEnv->GetMethodID(ClassPackageManager, "getActivityInfo", "(Landroid/content/ComponentName;I)Landroid/content/pm/ActivityInfo;");
+
+    // todo: do not hardcode the GET_META_DATA integer value but retrieve it instead
+    jobject ObjectActivityInfo = lJNIEnv->CallObjectMethod(ObjectPackageManager, MethodGetActivityInfo, ObjectComponentName, (jint)128);
+
+    // Load our libraries in reverse order
+    loadLibrary("stlport_shared", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("sfml-system", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("sfml-window", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("jpeg", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("freetype", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("sfml-graphics", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("ogg", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("FLAC", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("vorbis", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("vorbisenc", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("sndfile", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("openal", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("sfml-audio", lJNIEnv, ObjectActivityInfo);
+    loadLibrary("sfml-network", lJNIEnv, ObjectActivityInfo);
+    void* handle = loadLibrary("sfml-example", lJNIEnv, ObjectActivityInfo);
+
+    // todo: should we detach the current thread ? because if we do, it
+    // crashes (lJavaVM->DetachCurrentThread();)
+
+    // Call the original ANativeActivity_onCreate function
+    void (*ANativeActivity_onCreate)(ANativeActivity*, void*, size_t) = dlsym(handle, "ANativeActivity_onCreate");
+
+    if (!ANativeActivity_onCreate)
+    {
+        LOGE("sfml-activity: Undefined symbol ANativeActivity_onCreate");
+        exit(1);
+    }
+
+    ANativeActivity_onCreate(activity, savedState, savedStateSize);
+}