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LibreOffice Android
*******************
Bootstrap
*********
Contains common code for all projects on Android to bootstrap LibreOffice. In
addition it is a home to LibreOfficeKit (LOK - see libreofficekit/README) JNI
classes.
LOAndroid3 (in experimental)
****************************
LibreOffice Android application - the code is based on Fennec (Firefox for Android).
It uses OpenGL ES 2 for rendering of the document tiles which are gathered from
LibreOffice using LOK. The application contains the LibreOffice core in one shared
library: liblo-native-code.so, which is bundled together with the application.
TiledRendering
**************
Tiled rendering is a technique that splits the document to bitmaps of same size
(typically 256x256) which are fetched on demand.
Architecture and Threading
**************************
The application implements editing support using 4 threads:
1. The Android UI thread, we can't perform anything here that would take a considerable
amount of time.
2. An OpenGL thread which contains the OpenGL context and is responsible for drawing
all layers (including tiles) to the screen.
3. A thread (LOKitThread), that performs LibreOfficeKit calls, which may take more time
to complete. In addition it also receives events from the soffice thread (see below)
when the callback emits an event. Events are stored in a blocking queue (thread
processes events in FCFS order, goes to sleep when no more event is available and
awakens when there are events in queue again).
4. A native thread created by LibreOfficeKit (we call it the soffice thread), where
LibreOffice itself runs. It receives calls from LOKitThread, and may emit callback
events as necessary.
Android-specific notes
**********************
Note that this document has not necessarily been updated to match
reality...
For instructions on how to build for Android, see README.cross.
* Getting something running on an emulated device
Create an AVD in the android UI, don't even try to get
the data partition size right in the GUI, that is doomed to producing
an AVD that doesn't work. Instead start it from the console:
LD_LIBRARY_PATH=$(pwd)/lib emulator-arm -avd <Name> -partition-size 500
In order to have proper acceleration, you need the 32-bit libGL.so:
sudo zypper in Mesa-libGL-devel-32bit
Where <Name> is the literal name of the AVD that you entered.
Then:
cd android/experimental/LOAndroid3
ant debug install
adb logcat
And if all goes well - you should have some nice debug output to enjoy
when you start the app. After a while of this loop you might find that you have
lost a lot of space on your emulator's or device's /data volume. If using the
emulator, you can do:
adb shell stop; adb shell start
but on a (non-rooted) device you probably just need to reboot it. On the other
hand, this phenomenon might not happen on actual devices.
* What about using a real device?
That works fine, too.
* Debugging
First of all, you need to configure the build with --enable-debug or
--enable-dbgutil. You may want to provide --enable-selective-debuginfo too,
like --enable-selective-debuginfo="sw/" or so, in order to fit into the memory
during linking.
Building with all symbols is also possible but the linking is currently
slow (around 10 to 15 minutes) and you need lots of memory (around 16GB + some
swap).
You also want to avoid --with-android-package-name (or when you use
that, you must set it to "org.libreoffice"), otherwise ndk-gdb will complain
that
ERROR: Could not extract package's data directory. Are you sure that
your installed application is debuggable?
When you have all this, install the .apk to the device, and:
cd android/experimental/LOAndroid3
<android-ndk-r10d>/ndk-gdb --adb=<android-sdk-linux>/platform-tools/adb --start
Pretty printers aren't loaded automatically due to the single shared
object, but you can still load them manually. E.g. to have a pretty-printer for
rtl::OString, you need:
(gdb) python sys.path.insert(0, "/master/solenv/gdb")
(gdb) source /master/instdir/program/libuno_sal.so.3-gdb.py
* Debuggint the Java part
At the moment the code is not organized in a way that would make Eclipse or
Android Studio happy as-is, so the quickest way is to use the jdb command-line
debugger. Steps to use it:
1) Find out the JDWP ID of a debuggable application:
adb jdwp
From the list of currently active JDWP processes, the last number is the just
started debuggable application.
2) Forward the remote JDWP port/process ID to a local port:
adb forward tcp:7777 jdwp:31739
3) Connect to the running application:
jdb -sourcepath src/java/ -attach localhost:7777
Assuming that you're already in the LOAndroid3 directory in your shell.
* Common Errors / Gotchas
lo_dlneeds: Could not read ELF header of /data/data/org.libreoffice...libfoo.so
This (most likely) means that the install quietly failed, and that
the file is truncated; check it out with adb shell ls -l /data/data/....
* Detailed explanation
Note: the below talk about unit tests is obsolete; we no longer have
any makefilery etc to build unit tests for Android.
Unit tests are the first thing we want to run on Android, to get some
idea how well, if at all, the basic LO libraries work. We want to
build even unit tests as normal Android apps, i.e. packaged as .apk
files, so that they run in a sandboxed environment like that of
whatever eventual end-user Android apps there will be that use LO
code.
Sure, we could quite easily build unit tests as plain Linux
executables (built against the Android libraries, of course, not
GNU/Linux ones), push them to the device or emulator with adb and run
them from adb shell, but that would not be a good test as the
environment such processs run in is completely different from that in
which real end-user apps with GUI etc run. We have no intent to
require LibreOffice code to be used only on "rooted" devices etc.
All Android apps are basically Java programs. They run "in" a Dalvik
(or on Android 5 or newer - ART) virtual machine. Yes, you can also
have apps where all *your* code is native code, written in a compiled
language like C or C++. But also also such apps are actually started
by system-provided Java bootstrapping code (NativeActivity) running
in a Dalvik VM.
Such a native app (or actually, "activity") is not built as a
executable program, but as a shared object. The Java NativeActivity
bootstrapper loads that shared object with dlopen.
Anyway, our current "experimental" apps are not based on NativeActivity.
They have normal Java code for the activity, and just call out to a single,
app-specific native library (called liblo-native-code.so) to do all the
heavy lifting.
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