The Android NDK provides tools that allow Android application developers -to embed components that make use of native code in their Android applications. -
- -Android applications run in the Dalvik virtual machine. The NDK allows -developers to implement parts of their applications using native-code languages -such as C and C++. This can provide benefits to certain classes of applications, -in the form of reuse of existing code and in some cases increased speed.
- -The NDK provides:
- -This release of the NDK supports two ARM instruction sets:
-ARMv5TE machine code will run on all ARM-based Android devices. ARMv7-A will -run only on devices such as the Verizon Droid or Google Nexus One that have a -compatible CPU. The main difference between the two instruction sets is that -ARMv7-A supports hardware FPU and Thumb-2 instructions. You can target either or -both of the instruction sets — ARMv5TE is the default, but switching to -ARMv7-A is as easy as adding a single line to the application's Application.mk -file, without needing to change anything else in the file. You can also build -for both architectures at the same time and have everything stored in the final -.apk. Complete information is provided in the CPU-ARCH-ABIS.TXT in the NDK -package.
- -The NDK provides stable headers for libc (the C library), libm (the Math -library), OpenGL ES (3D graphics library), the JNI interface, and other -libraries, as listed in the section below.
- -The NDK will not benefit most applications. As a developer, you will need -to balance its benefits against its drawbacks; notably, using native code does -not result in an automatic performance increase, but does always increase -application complexity. Typical good candidates for the NDK are self-contained, -CPU-intensive operations that don't allocate much memory, such as signal processing, -physics simulation, and so on. Simply re-coding a method to run in C usually does -not result in a large performance increase. The NDK can, however, can be -an effective way to reuse a large corpus of existing C/C++ code.
- -Please note that the NDK does not enable you to develop native-only -applications. Android's primary runtime remains the Dalvik virtual machine.
- -The NDK includes a set of cross-toolchains (compilers, linkers, etc..) that -can generate native ARM binaries on Linux, OS X, and Windows (with Cygwin) -platforms.
- -It provides a set of system headers for stable native APIs that are -guaranteed to be supported in all later releases of the platform:
- -The NDK also provides a build system that lets you work efficiently with your -sources, without having to handle the toolchain/platform/CPU/ABI details. You -create very short build files to describe which sources to compile and which -Android application will use them — the build system compiles the sources -and places the shared libraries directly in your application project.
- -Important: With the exception of the -libraries listed above, native system libraries in the Android platform are -not stable and may change in future platform versions. -Your applications should only make use of the stable native system -libraries provided in this NDK.
- -The NDK package includes a set of documentation that describes the
-capabilities of the NDK and how to use it to create shared libraries for your
-Android applications. In this release, the documentation is provided only in the
-downloadable NDK package. You can find the documentation in the
-<ndk>/docs/ directory. Included are these files:
Additionally, the package includes detailed information about the "bionic"
-C library provided with the Android platform that you should be aware of, if you
-are developing using the NDK. You can find the documentation in the
-<ndk>/docs/system/libc/ directory:
The NDK includes four sample Android applications that illustrate how to use -native code in your Android applications:
- -hello-jni — a simple application that loads a string from
-a native method implemented in a shared library and then displays it in the
-application UI. two-libs — a simple application that loads a shared
-library dynamically and calls a native method provided by the library. In this
-case, the method is implemented in a static library that is imported by the
-shared library. san-angeles — a simple application that renders 3D
-graphics through the native OpenGL ES APIs, while managing activity lifecycle
-with a {@link android.opengl.GLSurfaceView GLSurfaceView} object. hello-gl2 — a simple application that renders a triangle
-using OpenGL ES 2.0 vertex and fragment shaders.For more information, see Using the Sample -Applications.
- -The sections below describe the system and software requirements for using -the Android NDK, as well as platform compatibility considerations that affect -appplications using libraries produced with the NDK.
- -<uses-sdk>
-element in its manifest file, with an android:minSdkVersion attribute
-value of "3" or higher. For example:
-
-<manifest> - ... - <uses-sdk android:minSdkVersion="3" /> - ... -</manifest>- -
Additionally, if you use this NDK to create a native library that uses the -OpenGL ES APIs, the application containing the library can be deployed only to -devices running the minimum platform versions described in the table below.
- -| Version | -Platform Compatibility | -
|---|---|
| OpenGL ES 1.1 | Android 1.6 (API Level 4) or higher |
| OpenGL ES 2.0 | Android 2.0 (API Level 5) or higher |
To ensure compatibility, the application must declare the proper
-android:minSdkVersion attribute value, as given in the table
-above.
For more information about API Level and its relationship to Android -platform versions, see -Android API Levels.
Installing the NDK on your development computer is straightforward and -involves extracting the NDK from its download package and running a host-setup -script.
- -Before you get started make sure that you have downloaded the latest Android SDK and upgraded your applications -and environment as needed. The NDK will not work with older versions of the -Android SDK. Also, take a moment to review the System -and Software Requirements for the NDK, if you haven't already.
- -To install the NDK, follow these steps:
- -android-ndk-<version>. You can rename the NDK directory if
-necessary and you can move it to any location on your computer. This
-documentation refers to the NDK directory as <ndk>. <ndk>/build/host-setup.sh
If the script completes successfully, it prints a "Host setup complete." -message. If it fails, it prints instructions that you can follow to correct any -problems.
-Once you have run the host-setup script, you are ready start working with the -NDK.
- -Once you've installed the NDK successfully, take a few minutes to read the
-documentation included in the NDK. You can find the documentation in the
-<ndk>/docs/ directory. In particular, please read the
-OVERVIEW.TXT document completely, so that you understand the intent of the NDK
-and how to use it.
If you used a previous version of the NDK, take a moment to review the -list of NDK changes in the CHANGES.TXT document.
- -Here's the general outline of how you work with the NDK tools:
- -<project>/jni/...<project>/jni/Android.mk to
-describe your native sources to the NDK build system<ndk>/apps/<my_app>/Application.mk to
-describe your Android application and native sources it needs to the NDK build
-system. This file sets up the link between an Android SDK application project
-and any number of shared libraries defined in the
-<project>/jni/ folder and it specifies the path to the
-application project that will receive the shared library built from the
-sources.$ make APP=<my_app>
The build tools copy the stripped, shared libraries needed by your -application to the proper location in the application's project directory.
-For complete information on all of the steps listed above, please see the -documentation included with the NDK package.
- - -The NDK includes four sample applications that illustrate how to use native -code in your Android applications:
- -hello-jni — a simple application that loads a string from
-a native method implemented in a shared library and then displays it in the
-application UI. two-libs — a simple application that loads a shared
-library dynamically and calls a native method provided by the library. In this
-case, the method is implemented in a static library imported by the shared
-library. san-angeles — a simple application that renders 3D
-graphics through the native OpenGL ES APIs, while managing activity lifecycle
-with a {@link android.opengl.GLSurfaceView GLSurfaceView} object. hello-gl2 — a simple application that renders a triangle
-using OpenGL ES 2.0 vertex and fragment shaders.For each sample, the NDK includes an Android application project, as well as
-the corresponding C source code and the necessary Android.mk and Application.mk
-files. The application projects are provided in
-<ndk>/apps/<app_name>/project/ and the C source for
-each application is provided in
-<ndk>/apps/<app_name>/project/jni/.
Once you have installed the NDK, you can build the shared libraries from the -NDK by using these commands from the root of the NDK directory:
-$ make APP=hello-jni — compiles
-<ndk>/apps/hello-jni/project/jni/hello-jni.c and outputs a
-shared library to
-<ndk>/apps/hello-jni/project/libs/armeabi/libhello-jni.so.
-$ make APP=two-libs — compiles
-<ndk>/apps/two-libs/project/jni/second.c and
-first.c and outputs a shared library to
-<ndk>/apps/two-libs/project/libs/armeabi/libtwolib-second.so.
-Next, build the sample Android applications that use the shared -libraries:
- -<ndk>/apps/<app_name>/project/. Then, set up an AVD, if
-necessary, and build/run the application in the emulator. For more information
-about creating a new Android project in Eclipse, see Developing in
-Eclipse.android tool to create
-the build file for each of the sample projects at
-<ndk>/apps/<app_name>/project/. Then set up an AVD, if
-necessary, build your project in the usual way, and run it in the emulator.
-For more information, see Developing in Other
-IDEs.If you have questions about the NDK or would like to read or contribute to -discussions about it, please visit the android-ndk group and -mailing list.
- - diff --git a/docs/html/sdk/sdk_toc.cs b/docs/html/sdk/sdk_toc.cs index 8ef1176ac2475..556f78164241b 100644 --- a/docs/html/sdk/sdk_toc.cs +++ b/docs/html/sdk/sdk_toc.cs @@ -126,8 +126,7 @@ Windows, r3 new!