| <html><body><pre>Android NDK How-To: |
| =================== |
| |
| A collection of tips and tricks for NDK users |
| |
| |
| How to force the display of build commands: |
| ------------------------------------------- |
| |
| Do "ndk-build V=1" and actual build commands will be |
| displayed. This can be used to verify that things are compiled |
| as you expect them to, and check for bugs in the NDK build system. |
| |
| (The V=1 trick comes from the Linux kernel build system) |
| |
| |
| How to force a rebuild of all your sources: |
| ------------------------------------------- |
| |
| Use GNU Make's "-B" option, as in: |
| |
| ndk-build -B |
| |
| |
| How to store your native sources in a location other than $PROJECT/jni: |
| ----------------------------------------------------------------------- |
| |
| First, you can simply tell your $PROJECT/jni/Android.mk to include |
| another Android.mk that are located in different places. |
| |
| Alternatively, you can define APP_BUILD_SCRIPT in your Application.mk |
| to point to an alternative Android.mk file. |
| |
| |
| How to build a project's native files without cd-ing to it: |
| ----------------------------------------------------------- |
| |
| Sometimes, you may need to rebuild a project's native file without |
| being able to cd to its top-level path from the command-line. This |
| is do-able by using the GNU-Make '-C <path>' option, as in: |
| |
| ndk-build -C <project-path> |
| |
| |
| How to store your Application.mk in a location other than $PROJECT/jni: |
| ----------------------------------------------------------------------- |
| |
| Starting with NDK r4, you can simply place the file under $PROJECT/jni/ |
| and launch the 'ndk-build' script from your project tree. |
| |
| If you want to use 'ndk-build' but place the file to a different location, |
| use a GNU Make variable override as: |
| |
| ndk-build NDK_APPLICATION_MK=/path/to/your/Application.mk |
| |
| If you're using the legacy $NDK/apps/<name> build method, you can create |
| a symbolic link to your final Application.mk there. For example, imagine |
| that you wrote: |
| |
| $PROJECT/foo/Application.mk |
| |
| You can create a symlink like with a command like: |
| |
| ln -s $PROJECT/foo $NDK/apps/<name> |
| |
| This will make $NDK/apps/<name>/Application.mk point directly to |
| $PROJECT/jni/Application.mk |
| |
| Note that generated files will still go under $NDK/out/apps/<name> though. |
| |
| Windows users: The NDK is only supported on Cygwin, which implements |
| symbolic links through the "ln -s" command, as in: |
| |
| ln -s <target> <link> |
| |
| |
| How to properly add include directories to your module declaration: |
| ------------------------------------------------------------------- |
| |
| If you define several modules, it is common to need to include one |
| module's header while compiling another one. For example, consider |
| the following example: |
| |
| $PROJECT/jni/foo/ |
| Android.mk |
| foo.h |
| foo.c |
| |
| $PROJECT/jni/bar/ |
| Android.mk |
| bar.c |
| |
| Where the 'bar.c' uses '#include <foo.h>'. You will need to add the |
| path to the 'foo' module in jni/bar/Android.mk to build it properly. |
| |
| One is tempted to use the following: |
| |
| LOCAL_C_INCLUDES := ../foo |
| |
| However this will not work because all compilation happens from the |
| directory where 'ndk-build' is invoked, and include files must be |
| relative to it. |
| |
| The correct line is instead: |
| |
| LOCAL_C_INCLUDES := $(LOCAL_PATH)/../foo |
| |
| Which uses a path relative to $(LOCAL_PATH), in the case where you would |
| need to move 'foo' and 'bar' to a deeper level in the 'sources' hierarchy. |
| |
| In case you absolutely need it, you can also use NDK_APP_PROJECT_PATH to |
| point to your project directory: |
| |
| LOCAL_C_INCLUDES := $(NDK_APP_PROJECT_PATH)/jni/foo |
| |
| However, we don't recommend using this, paths relative to $(LOCAL_PATH) |
| being better. |
| |
| </pre></body></html> |
