Moving to Android NDK 1.6 from Android NDK 1.5 ...

I've updated my Android configuration to NDK 1.6, and am using the latest STLPort download.

There were a few things that changed, mainly system paths, as some posters to my blog were kind enough to point-out in earlier posts.

Here are some notes on that process, from the point of view of a cygwin-based setup under Windows. The comments generally apply to Linux/Mac as well, however.

Getting STLPort

I performed the "git" command for STLPort from within the root of the Android NDK folder, in other words from within this folder:

C:\android-ndk-1.6_r1

The command to use is this:

git clone git://umbel.mooo.com/ndk-wrappers.git

This puts the STLPort code in a slightly different place to where it was before, such that the code appears under the ndk-wrappers folder...


ndk-wrappers\stlport


... which you'll need to account for when you update the paths!

There were a couple of other things that I found tricky to get right in this transition were as follows.

env.sh

When you try running env.sh, you must do it with "source" otherwise the environment isn't updated properly. In other words, type this:

source ./env.sh


Application.mk

If your project is called "fred", then you need to have the following folder:

C:\android-ndk-1.6_r1\apps\fred

This should contain just one item, which is the Application.mk file, with the following (example!) two lines in it:

APP_PROJECT_PATH := /cygdrive/c/DOCUME~1/me/MYDOCU~1/WORKSP~1/fred
APP_MODULES := fred

libstlport.a

Once you've rebuilt STLPort, you need to copy libstlport.a (which seemed to be called libstlport.5.1.a in the previous build system... again, watch out for that!) to a new folder, which you'll need to create in the following location:

C:\android-ndk-1.6_r1\out\apps\fred\libs

The jni folder

You need to have at least two files (your source .cc file, and your Android.mk file) in the jni folder under your project, which is here in my example:

C:\Documents and Settings\me\My Documents\workspace\fred\jni

Android.mk

In my example, the Android.mk file contains this data:


LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

STLPORT_BASE := /cygdrive/c/android-ndk-1.6_r1/ndk-wrappers/stlport


LOCAL_MODULE := fred
LOCAL_CPP_EXTENSION := .cc
LOCAL_CFLAGS += -I$(STLPORT_BASE)/stlport \
-D__NEW__ \
-D__SGI_STL_INTERNAL_PAIR_H \
-DANDROID \
-DOS_ANDROID
LOCAL_SRC_FILES := fred.cc

#Static Libraries:
LOCAL_PREBUILT_LIBS := libs/libstlport.a
include $(BUILD_MULTI_PREBUILT)
LOCAL_STATIC_LIBRARIES := libs/libstlport

include $(BUILD_SHARED_LIBRARY)


Good luck!

That should be enough to get you up-and-running with NDK 1.6!

Android NDK - getting STLPort up and running

If you want to get STLPort running with the Android NDK, you'll have a bit of work to do; especially if using Cygwin under Windows.

First, visit http://umbel.mooo.com/ and get the STLPort version from John Ripley (great job, John!). If you're a cygwin user, you'll first need to remember to install the git package.

Next thing is to copy the files to a place that works for you. On my system, I copied the files into my c:\android-ndk-1.5_r1 folder, and then moved the two hello-stl folders to somewhere that seemed consistent with the other NDK files:


C:\android-ndk-1.5_r1\apps\hello-stl
C:\android-ndk-1.5_r1\sources\samples\hello-stl


I then had to change a few files before I could build the STLPort...

setup.sh

Change the top few lines to look like this:

#!/bin/bash
if uname | grep -qi linux; then
export NDK_HOST=linux-x86
elif uname | grep -qi CYGWIN; then
export NDK_HOST=windows
else
export NDK_HOST=darwin-x86
fi

Change the third line up from the bottom to look like this:


ln -sf "$NDK_DIR/build/prebuilt/${NDK_HOST}/arm-eabi-4.2.1/bin/arm-eabi-$tool" arm-linux-$tool


stlport/build/lib/android.mak

Change the TOOLCHAIN_PREFIX line to look like this:


TOOLCHAIN_PREFIX := $(NDK_DIR)/build/prebuilt/$(NDK_HOST)/arm-eabi-4.2.1/bin/arm-eabi-


sources/samples/hello-stl/Android.mk

Change the STLPORT_BASE line to be this:


STLPORT_BASE := /cygdrive/c/android-ndk-1.5_r1/stlport


Change this:


LOCAL_LDLIBS += -L$(STLPORT_BASE)/build/lib/obj/gcc/so \
-lstlport


to this:


LOCAL_STATIC_LIBRARIES := libstlport.5.1


---

Building STLPort

Now that the files are merged-in, you're ready to build STLPort!

Run the following in the cygwin shell... it will build the STLPort static library for you! You'll only need to do this once.


export NDK_DIR=/cygdrive/c/android-ndk-1.5-r1
cd $NDK_DIR
./env.sh
./setup.sh


Now, do this to copy the file to your project:


cp -p \
/cygdrive/c/android-ndk-1.5_r1\stlport\build\lib\obj\gcc\ar\libstlport.5.1.a \
/cygdrive/c/android-ndk-1.5_r1\out\apps\hello-stl\android-1.5-arm


---

Building your project's shared library

You can now go back to the cygwin shell, and do this:


cd /cygdrive/c/android-ndk-1.5_r1
make APP=hello-stl


... which will build your shared library file:

C:\android-ndk-1.5_r1\apps\hello-stl\project\libs\armeabi\libhello-stl.so


Note that this will have the static STLPort library linked-in.

Building the hello-stl project

From Eclipse, use the New Project Wizard to create a new Android project for each sample, using the "Import from Existing Source" option and import the source from c:\android-ndk-1.5_r1\apps\hello-stl\project

You can now build and run your project. The string displayed comes from the shared library, using std::string ...!

Android JNI NDK - and STL support?

There is an interesting post that you can find here, which indicates that it is possible to get STL support working in C++ code that you might want to port to the Android JNI / NDK, using STLPort. Cool!

This is really interesting; I think this was the biggest issue that was blocking a port of Mixtikl to Android devices (I think I can see a way around most other issues). So, I now need to clear some time in my schedule to investigate in more detail! :)

The STLPort info page has more details, and the license looks promising; all-in-all, this is very exciting!