cocos2d 跨平台原理 以及android.mk编译的入口

在android工程下面jni/hellocpp/main.cpp里面是cocos2d c++的入口。

一路跟踪Cocos2dxActivity.java找到Cocos2dxRenderer.java

public void onSurfaceCreated(final GL10 pGL10, final EGLConfig pEGLConfig) {        Cocos2dxRenderer.nativeInit(this.mScreenWidth, this.mScreenHeight);        this.mLastTickInNanoSeconds = System.nanoTime();        mNativeInitCompleted = true;    }

调用native方法nativeInit创建glView。

其中nativeInit方法在cocos/platform/android/javaactivity-android.cpp可以看到

java层是怎么能够找的到javaactivity-android.cpp这个文件呢？

在obj目录下可以看到javaactivity-android.o文件

但是这个文件在什么时候在哪里编译的呢？

右键工程可以看到会执行目录下的build_native.py

在build_native.py里面可以看到一段函数

def do_build(cocos_root, ndk_root, app_android_root,ndk_build_param,sdk_root,android_platform,build_mode):    ndk_path = os.path.join(ndk_root, "ndk-build")    num_of_cpu = get_num_of_cpu()    if ndk_build_param == None:        command = '%s -j%d -C %s NDK_DEBUG=%d' % (ndk_path, num_of_cpu, app_android_root, build_mode=='debug')    else:        command = '%s -j%d -C %s NDK_DEBUG=%d %s' % (ndk_path, num_of_cpu, app_android_root, build_mode=='debug', ' '.join(str(e) for e in ndk_build_param))    if os.system(command) != 0:        raise Exception("Build dynamic library for project [ " + app_android_root + " ] fails!")    elif android_platform is not None:      sdk_tool_path = os.path.join(sdk_root, "tools/android")      cocoslib_path = os.path.join(cocos_root, "cocos/platform/android/java")      command = '%s update lib-project -t %s -p %s' % (sdk_tool_path,android_platform,cocoslib_path)       if os.system(command) != 0:        raise Exception("update cocos lib-project [ " + cocoslib_path + " ] fails!")          command = '%s update project -t %s -p %s -s' % (sdk_tool_path,android_platform,app_android_root)      if os.system(command) != 0:        raise Exception("update project [ " + app_android_root + " ] fails!")              buildfile_path = os.path.join(app_android_root, "build.xml")      command = 'ant clean %s -f %s -Dsdk.dir=%s' % (build_mode,buildfile_path,sdk_root)      os.system(command)

打印执行的命令可以看到

xx\android-ndk-r10c\ndk-build -j4 -C xx\Projects\cake\proj.android NDK_DEBUG=0

ndk-build 其实就是对GNU Make的封装，它的目的是调用正确的NDK编译脚本，它等价于 make -f $NDK/build/core/build-local.mk [参数]
打开build-local.mk

可以看到关于jni目录下的application.mk和android.mk信息。

可见这就是编译C++文件的入口。

再看android.mk

其中$(call import-module,.)会引入上面add-path下的外部android.mk文件

可以看到cocos目录下有个android.mk文件

LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE := cocos2dx_internal_staticLOCAL_MODULE_FILENAME := libcocos2dxinternalLOCAL_SRC_FILES := \cocos2d.cpp \2d/CCAction.cpp \2d/CCActionCamera.cpp \2d/CCActionCatmullRom.cpp \2d/CCActionEase.cpp \2d/CCActionGrid.cpp \2d/CCActionGrid3D.cpp \2d/CCActionInstant.cpp \2d/CCActionInterval.cpp \2d/CCActionManager.cpp \2d/CCActionPageTurn3D.cpp \2d/CCActionProgressTimer.cpp \2d/CCActionTiledGrid.cpp \2d/CCActionTween.cpp \2d/CCAnimation.cpp \2d/CCAnimationCache.cpp \2d/CCAtlasNode.cpp \2d/CCCamera.cpp \2d/CCClippingNode.cpp \2d/CCClippingRectangleNode.cpp \2d/CCComponent.cpp \2d/CCComponentContainer.cpp \2d/CCDrawNode.cpp \2d/CCDrawingPrimitives.cpp \2d/CCFont.cpp \2d/CCFontAtlas.cpp \2d/CCFontAtlasCache.cpp \2d/CCFontCharMap.cpp \2d/CCFontFNT.cpp \2d/CCFontFreeType.cpp \2d/CCGLBufferedNode.cpp \2d/CCGrabber.cpp \2d/CCGrid.cpp \2d/CCLabel.cpp \2d/CCLabelAtlas.cpp \2d/CCLabelBMFont.cpp \2d/CCLabelTTF.cpp \2d/CCLabelTextFormatter.cpp \2d/CCLayer.cpp \2d/CCLight.cpp \2d/CCMenu.cpp \2d/CCMenuItem.cpp \2d/CCMotionStreak.cpp \2d/CCNode.cpp \2d/CCNodeGrid.cpp \2d/CCParallaxNode.cpp \2d/CCParticleBatchNode.cpp \2d/CCParticleExamples.cpp \2d/CCParticleSystem.cpp \2d/CCParticleSystemQuad.cpp \2d/CCProgressTimer.cpp \2d/CCProtectedNode.cpp \2d/CCRenderTexture.cpp \2d/CCScene.cpp \2d/CCSprite.cpp \2d/CCSpriteBatchNode.cpp \2d/CCSpriteFrame.cpp \2d/CCSpriteFrameCache.cpp \2d/CCTMXLayer.cpp \2d/CCFastTMXLayer.cpp \2d/CCTMXObjectGroup.cpp \2d/CCTMXTiledMap.cpp \2d/CCFastTMXTiledMap.cpp \2d/CCTMXXMLParser.cpp \2d/CCTextFieldTTF.cpp \2d/CCTileMapAtlas.cpp \2d/CCTransition.cpp \2d/CCTransitionPageTurn.cpp \2d/CCTransitionProgress.cpp \2d/CCTweenFunction.cpp \platform/CCGLView.cpp \platform/CCFileUtils.cpp \platform/CCSAXParser.cpp \platform/CCThread.cpp \platform/CCImage.cpp \math/CCAffineTransform.cpp \math/CCGeometry.cpp \math/CCVertex.cpp \math/Mat4.cpp \math/MathUtil.cpp \math/Quaternion.cpp \math/TransformUtils.cpp \math/Vec2.cpp \math/Vec3.cpp \math/Vec4.cpp \base/CCAutoreleasePool.cpp \base/CCConfiguration.cpp \base/CCConsole.cpp \base/CCData.cpp \base/CCDataVisitor.cpp \base/CCDirector.cpp \base/CCEvent.cpp \base/CCEventAcceleration.cpp \base/CCEventCustom.cpp \base/CCEventDispatcher.cpp \base/CCEventFocus.cpp \base/CCEventKeyboard.cpp \base/CCEventController.cpp \base/CCEventListener.cpp \base/CCEventListenerController.cpp \base/CCEventListenerAcceleration.cpp \base/CCEventListenerCustom.cpp \base/CCEventListenerFocus.cpp \base/CCEventListenerKeyboard.cpp \base/CCEventListenerMouse.cpp \base/CCEventListenerTouch.cpp \base/CCEventMouse.cpp \base/CCEventTouch.cpp \base/CCIMEDispatcher.cpp \base/CCNS.cpp \base/CCProfiling.cpp \base/ccRandom.cpp \base/CCRef.cpp \base/CCScheduler.cpp \base/CCScriptSupport.cpp \base/CCTouch.cpp \base/CCUserDefault.cpp \base/CCUserDefault-android.cpp \base/CCValue.cpp \base/TGAlib.cpp \base/ZipUtils.cpp \base/atitc.cpp \base/base64.cpp \base/ccCArray.cpp \base/ccFPSImages.c \base/ccTypes.cpp \base/ccUTF8.cpp \base/ccUtils.cpp \base/etc1.cpp \base/pvr.cpp \base/s3tc.cpp \base/CCController.cpp \base/CCController-android.cpp \base/ObjectFactory.cpp \renderer/CCBatchCommand.cpp \renderer/CCCustomCommand.cpp \renderer/CCGLProgram.cpp \renderer/CCGLProgramCache.cpp \renderer/CCGLProgramState.cpp \renderer/CCGLProgramStateCache.cpp \renderer/CCGroupCommand.cpp \renderer/CCQuadCommand.cpp \renderer/CCMeshCommand.cpp \renderer/CCRenderCommand.cpp \renderer/CCRenderer.cpp \renderer/CCTexture2D.cpp \renderer/CCTextureAtlas.cpp \renderer/CCTextureCache.cpp \renderer/ccGLStateCache.cpp \renderer/ccShaders.cpp \renderer/CCVertexIndexBuffer.cpp \renderer/CCVertexIndexData.cpp \renderer/CCPrimitive.cpp \renderer/CCPrimitiveCommand.cpp \renderer/CCTrianglesCommand.cpp \deprecated/CCArray.cpp \deprecated/CCSet.cpp \deprecated/CCString.cpp \deprecated/CCDictionary.cpp \deprecated/CCDeprecated.cpp \deprecated/CCNotificationCenter.cpp \physics/CCPhysicsBody.cpp \physics/CCPhysicsContact.cpp \physics/CCPhysicsJoint.cpp \physics/CCPhysicsShape.cpp \physics/CCPhysicsWorld.cpp \physics/chipmunk/CCPhysicsBodyInfo_chipmunk.cpp \physics/chipmunk/CCPhysicsContactInfo_chipmunk.cpp \physics/chipmunk/CCPhysicsJointInfo_chipmunk.cpp \physics/chipmunk/CCPhysicsShapeInfo_chipmunk.cpp \physics/chipmunk/CCPhysicsWorldInfo_chipmunk.cpp \../external/ConvertUTF/ConvertUTFWrapper.cpp \../external/ConvertUTF/ConvertUTF.c \../external/tinyxml2/tinyxml2.cpp \../external/unzip/ioapi_mem.cpp \../external/unzip/ioapi.cpp \../external/unzip/unzip.cpp \../external/edtaa3func/edtaa3func.cpp \../external/xxhash/xxhash.cLOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH) \                    $(LOCAL_PATH)/. \                    $(LOCAL_PATH)/.. \                    $(LOCAL_PATH)/platform \                    $(LOCAL_PATH)/base \                    $(LOCAL_PATH)/../external \                    $(LOCAL_PATH)/../external/tinyxml2 \                    $(LOCAL_PATH)/../external/unzip \                    $(LOCAL_PATH)/../external/chipmunk/include/chipmunk \                    $(LOCAL_PATH)/../external/xxhash \                    $(LOCAL_PATH)/../external/nslogLOCAL_C_INCLUDES := $(LOCAL_PATH) \                    $(LOCAL_PATH)/. \                    $(LOCAL_PATH)/platform \                    $(LOCAL_PATH)/../external \                    $(LOCAL_PATH)/../external/tinyxml2 \                    $(LOCAL_PATH)/../external/unzip \                    $(LOCAL_PATH)/../external/chipmunk/include/chipmunk \                    $(LOCAL_PATH)/../external/edtaa3func \                    $(LOCAL_PATH)/../external/xxhash \                    $(LOCAL_PATH)/../external/ConvertUTF \                    $(LOCAL_PATH)/../external/nslogLOCAL_EXPORT_LDLIBS := -lGLESv2 \                       -llog \                       -lz \                       -landroidLOCAL_STATIC_LIBRARIES := cocos_freetype2_staticLOCAL_STATIC_LIBRARIES += cocos_png_staticLOCAL_STATIC_LIBRARIES += cocos_jpeg_staticLOCAL_STATIC_LIBRARIES += cocos_tiff_staticLOCAL_STATIC_LIBRARIES += cocos_webp_staticLOCAL_STATIC_LIBRARIES += cocos_chipmunk_staticLOCAL_WHOLE_STATIC_LIBRARIES := cocos2dxandroid_static# define the macro to compile through support/zip_support/ioapi.cLOCAL_CFLAGS   :=  -DUSE_FILE32APILOCAL_CPPFLAGS := -Wno-deprecated-declarations -Wno-extern-c-compatLOCAL_EXPORT_CFLAGS   := -DUSE_FILE32APILOCAL_EXPORT_CPPFLAGS := -Wno-deprecated-declarations -Wno-extern-c-compatifeq ($(TARGET_ARCH_ABI),armeabi-v7a)LOCAL_ARM_NEON  := trueendifinclude $(BUILD_STATIC_LIBRARY)#==============================================================include $(CLEAR_VARS)LOCAL_MODULE := cocos2dx_staticLOCAL_MODULE_FILENAME := libcocos2dLOCAL_STATIC_LIBRARIES := cocostudio_staticLOCAL_STATIC_LIBRARIES += cocosbuilder_staticLOCAL_STATIC_LIBRARIES += cocos3d_staticLOCAL_STATIC_LIBRARIES += spine_staticLOCAL_STATIC_LIBRARIES += cocos_network_staticLOCAL_STATIC_LIBRARIES += audioengine_staticinclude $(BUILD_STATIC_LIBRARY)#==============================================================$(call import-module,freetype2/prebuilt/android)$(call import-module,platform/android)$(call import-module,png/prebuilt/android)$(call import-module,jpeg/prebuilt/android)$(call import-module,tiff/prebuilt/android)$(call import-module,webp/prebuilt/android)$(call import-module,chipmunk/prebuilt/android)$(call import-module,3d)$(call import-module,audio/android)$(call import-module,editor-support/cocosbuilder)$(call import-module,editor-support/cocostudio)$(call import-module,editor-support/spine)$(call import-module,network)$(call import-module,ui)$(call import-module,extensions)$(call import-module,Box2D)$(call import-module,curl/prebuilt/android)$(call import-module,websockets/prebuilt/android)$(call import-module,protobuf-lite)

$(call import-module,audio/android)

这个下面也有android.mk文件javaactivity-android.o就是在这里编译的。

到这里一切就豁然开朗了。

参考链接:
http://blog.sina.com.cn/s/blog_4057ab62010197z8.html
http://blog.csdn.net/smfwuxiao/article/details/8523087