Ada on Android?

Ada on Android?

[Stephen Leake]

I managed to modify an open source music player written in Java to do
what I want on my new Android.

Now I want to make it even better, but I'm already tired of saying "I
wish this was in Ada!".

So I install GNAT GPL 2011 for jvm target, and ran jvm2ada on
android.jar (which generated about 2,900 files!, after some hiccups).

Then I tried building the Java hello world tutorial translated to Ada.
The compiler reported several bugs in the generated code; some obvious
errors (duplicate identifiers) some apparently compiler bugs. After
finding work-arounds for all of those, I finally hit a bug box that I
don't see how to fix.

I'm doing this at home, so I can't use my work AdaCore support contract
to get help.

Has anyone here done any Ada for Android?

I could compromise and write the GUI and Android API-intensive stuff in
Java and the rest in Ada, but for this program, most of it is GUI or
Android-intensive (there are a _lot_ of very nice facilities in the
Android API). So that would not gain much.

--
-- Stephe

Re: Ada on Android?

[onox]

On Sep 5, 7:22 pm, Stephen Leake <stephen_le...@stephe-leake.org>
wrote:
> I managed to modify an open source music player written in Java to do
> what I want on my new Android.
>
> Now I want to make it even better, but I'm already tired of saying "I
> wish this was in Ada!".
>
> So I install GNAT GPL 2011 for jvm target, and ran jvm2ada on
> android.jar (which generated about 2,900 files!, after some hiccups).
>
> Then I tried building the Java hello world tutorial translated to Ada.
> The compiler reported several bugs in the generated code; some obvious
> errors (duplicate identifiers) some apparently compiler bugs. After
> finding work-arounds for all of those, I finally hit a bug box that I
> don't see how to fix.
>
> I'm doing this at home, so I can't use my work AdaCore support contract
> to get help.
>
> Has anyone here done any Ada for Android?
>
> I could compromise and write the GUI and Android API-intensive stuff in
> Java and the rest in Ada, but for this program, most of it is GUI or
> Android-intensive (there are a _lot_ of very nice facilities in the
> Android API). So that would not gain much.
>
> --
> -- Stephe

You might be interested in checking the GNATDroid (Android 2.3+) cross-
compiler for FreeBSD at http://www.dragonlace.net/

Re: Ada on Android?

[Stephen Leake]

onox <denkpadje@gmail.com> writes:

> On Sep 5, 7:22 pm, Stephen Leake <stephen_le...@stephe-leake.org>
> wrote:
>> Has anyone here done any Ada for Android?
>>
>
> You might be interested in checking the GNATDroid (Android 2.3+) cross-
> compiler for FreeBSD at http://www.dragonlace.net/

I don't need to target ARM; the Android API is for the JVM target.

The problem is binding to the Android API; I don't see any mention of
that on the DragonLace.Net page.

-- 
-- Stephe

Re: Ada on Android?

[Brian Drummond]

On Mon, 05 Sep 2011 21:16:13 -0400, Stephen Leake wrote:

> onox <denkpadje@gmail.com> writes:
> 
>> On Sep 5, 7:22 pm, Stephen Leake <stephen_le...@stephe-leake.org>
>> wrote:
>>> Has anyone here done any Ada for Android?
>>>
>>>
>> You might be interested in checking the GNATDroid (Android 2.3+) cross-
>> compiler for FreeBSD at http://www.dragonlace.net/
> 
> I don't need to target ARM; the Android API is for the JVM target.

Was.

As of Android 2.3, the API has also been opened up to native (usually 
ARM) code. See
http://developer.android.com/sdk/ndk/index.html

There was some support for C on earlier Android versions but as of 2.3 
it's supposed to be complete and for C++ too. Performance aside, this may 
be a better approach than targetting the JVM. For example, is it possible 
the Ada compiler hits some difference between JVM and Dalvik that isn't 
important to the Java compiler?

This (in 2.3) was apparently intended as a sop to the C++ community but 
opens the way to Ada as well via the Dragonlace compiler (or my so far 
unsuccessful attempts at building FSF Gnat 4.6/4.7 to target Arm on 
Linux). 

> The problem is binding to the Android API; I don't see any mention of
> that on the DragonLace.Net page.

The NDK documentation will cover that (for C++ anyway); as far as I can 
see, it's a mess. You may not ever need Java but you will need the SDK's 
GUI builder (and from the SDK examples, that still requires hand editing 
XML!)

A GTKAda binding to that mess would be nice ... 
(though probably difficult to impossible)

Meanwhile, I think getting the ACATS suite to pass on Android is quite 
impressive. Kudos to jrmarino.

Here, I have FreeBSD going in VirtualBox on my laptop, and am working 
through installing the tools via ports. (GTK took 24 hours building 
several hundred packages from source; and now GPS insists on building an 
obsolete GCC4.5.x before it will install...) 

Then my cheap Flytouch pad is only Android 2.2(Froyo). I may have to look 
around for an upgrade to 2.3...

I'll report if/when I have a HelloWorld running.

But I think we're close.
- Brian

Re: Ada on Android?

[jrmarino]

On Sep 6, 12:33 pm, Brian Drummond <br...@shapes.demon.co.uk> wrote:
> Meanwhile, I think getting the ACATS suite to pass on Android is quite
> impressive. Kudos to jrmarino.

Thanks, Brian.

> Here, I have FreeBSD going in VirtualBox on my laptop, and am working
> through installing the tools via ports. (GTK took 24 hours building
> several hundred packages from source; and now GPS insists on building an
> obsolete GCC4.5.x before it will install...)

GPS meaning GNAT Programming Studio?  It doesn't require GCC 4.5.
Some other dependency must be pulling that in (probably in error).
GPS only requires GNAT-AUX to build.

John

Re: Ada on Android?

[Pascal Obry]

Le 05/09/2011 22:15, onox a �crit :
> You might be interested in checking the GNATDroid (Android 2.3+) cross-
> compiler for FreeBSD at http://www.dragonlace.net/

I haven't looked, but is there a script or instruction to build a cross 
for Android somewhere?

Pascal.

-- 

--|------------------------------------------------------
--| Pascal Obry                           Team-Ada Member
--| 45, rue Gabriel Peri - 78114 Magny Les Hameaux FRANCE
--|------------------------------------------------------
--|    http://www.obry.net  -  http://v2p.fr.eu.org
--| "The best way to travel is by means of imagination"
--|
--| gpg --keyserver keys.gnupg.net --recv-key F949BD3B

Re: Ada on Android?

[jrmarino]

On Sep 6, 6:54 pm, Pascal Obry <pas...@obry.net> wrote:
> Le 05/09/2011 22:15, onox a écrit :
>
> > You might be interested in checking the GNATDroid (Android 2.3+) cross-
> > compiler for FreeBSD athttp://www.dragonlace.net/
>
> I haven't looked, but is there a script or instruction to build a cross
> for Android somewhere?
>
> Pascal.
>

Pascal,
Only the GNAT-AUX repository has the necessary patches to build GNAT
for Android.  Unless somebody duplicates my work, any new android
cross-compiler would have use this codebase.

The ports listed on Dragonlace are being added to FreeBSD now, two of
the four are already committed.  When the final two get committed,
FreeBSD users with be able to do something like "cd /usr/ports/lang/
gnatdroid-armv7 && make install" to get their cross-compiler.  Users
of other OS's will have to use the FreeBSD makefiles as a template and
hopefully publish their work if successful.  I won't have time to port
this over to other hosts any time soon.

Regards,
John

Re: Ada on Android?

[Brian Drummond]

On Tue, 06 Sep 2011 05:08:30 -0700, jrmarino wrote:

>> ... and now GPS insists on building
>> an obsolete GCC4.5.x before it will install...)
> 
> GPS meaning GNAT Programming Studio?  It doesn't require GCC 4.5. Some
> other dependency must be pulling that in (probably in error). GPS only
> requires GNAT-AUX to build.

... finally, GCC4.5 built (after a frustrating time, trying to enlarge 
the virtualbox "disk" allocated to freeBSD). It appears LAPack requires 
GCC4.5, NumPy requires LAPack, Py26-gtk requires NumPy and so on...

Saw the GnatDroid ports in portsnap, just before I saw your other post. 
Cool...

- Brian

Re: Ada on Android?

[Stephen Leake]

Brian Drummond <brian@shapes.demon.co.uk> writes:

> On Mon, 05 Sep 2011 21:16:13 -0400, Stephen Leake wrote:
>
>> onox <denkpadje@gmail.com> writes:
>> 
>>> On Sep 5, 7:22 pm, Stephen Leake <stephen_le...@stephe-leake.org>
>>> wrote:
>>>> Has anyone here done any Ada for Android?
>>>>
>>>>
>>> You might be interested in checking the GNATDroid (Android 2.3+) cross-
>>> compiler for FreeBSD at http://www.dragonlace.net/
>> 
>> I don't need to target ARM; the Android API is for the JVM target.
>
> Was.
>
> As of Android 2.3, the API has also been opened up to native (usually 
> ARM) code. See
> http://developer.android.com/sdk/ndk/index.html
>
> There was some support for C on earlier Android versions but as of 2.3 
> it's supposed to be complete and for C++ too. Performance aside, this may 
> be a better approach than targetting the JVM. For example, is it possible 
> the Ada compiler hits some difference between JVM and Dalvik that isn't 
> important to the Java compiler?

I never got as far as actually trying to run things.

I'm writing a music player app, that uses lots of neat stuff (like a low
level music player) in the Android API. So I need to use the JVM.

The compiler bugs are encountered when trying to compile the specs of
the Ada binding to the API, not in the code generator. 

> This (in 2.3) was apparently intended as a sop to the C++ community
>but
> opens the way to Ada as well via the Dragonlace compiler (or my so far 
> unsuccessful attempts at building FSF Gnat 4.6/4.7 to target Arm on 
> Linux). 

Ada is supposed to be able to target the JVM; also being able to target
ARM is an orthogonal issue. Targeting the ARM would be useful for
compiling a new cryptographic library, for example. Totally unnecessary
for building a music player.

>> The problem is binding to the Android API; I don't see any mention of
>> that on the DragonLace.Net page.
>
> The NDK documentation will cover that (for C++ anyway); as far as I can 
> see, it's a mess. You may not ever need Java but you will need the SDK's 
> GUI builder (and from the SDK examples, that still requires hand editing 
> XML!)

I already have a working app written in Java; I found the Java source
code for the example music player written by Google, and adapted it. Not
hard, and I found the on-line Android API docs to be adequate, if not
outstanding. But I still want to redo it in Ada before I add more
features.

I'm don't understand what "SDK GUI Builder" you are talking about; I
used Eclipse and the Android toolkit, as the Hello World tutorial says.
And yes, the GUI builder suffers from the same WYSIAYG problems every
other GUI builder I've used has; editing XML was necessary, but also far
easier than trying to do the same thing in the GUI builder.

It is possible to do without the GUI builder by writing either Java or
Ada code that constructs the GUI; we have the same choice in GtkAda. I'm
going with the recommended approach to make sure I know what its
advantages are before I give up on it.

For example, that might be the best way to allow skin customizations,
which is a nice feature.

> A GTKAda binding to that mess would be nice ... 
> (though probably difficult to impossible)

Why would that be nice?

So far, the Android windowing stuff is _far_ cleaner and easier to use
than the equivalent GtkAda stuff. I don't have to immediately do unsafe
type conversions to write marshallers for my app event handlers; that's
all hidden. All I have to do is declare an overriding implementation of
a JVM class method.

I'm sure I will run into limitations with this method; I'm already
having trouble keeping track of what thread each method call is running
in (the API docs are _not_ clear about that; I'm assuming anything
called a "callback" can be running in a different thread than the read
of the app).

In fact, I'm thinking of writing a similar music player for Windows,
using the JVM and Java windowing stuff there. It may not be as clean as
Android, but it would be hard to be much worse than Gtk. The alternative
would be to try to write a plugin for VLC or one of the other existing
players: I have not looked into that yet, so I don't know what GUI
kit they use. 

> Meanwhile, I think getting the ACATS suite to pass on Android is quite 
> impressive. Kudos to jrmarino.

That is good, but not my need at the moment.

> Here, I have FreeBSD going in VirtualBox on my laptop, and am working 
> through installing the tools via ports. (GTK took 24 hours building 
> several hundred packages from source; and now GPS insists on building an 
> obsolete GCC4.5.x before it will install...) 
>
> Then my cheap Flytouch pad is only Android 2.2(Froyo). I may have to look 
> around for an upgrade to 2.3...
>
> I'll report if/when I have a HelloWorld running.

I'm talking about the full Android windowing Hello World at
http://developer.android.com/resources/tutorials/hello-world.html.

_not_ just Ada.Text_IO.Put_line.

> But I think we're close.

You are way overly optimistic. But that's a necessary attitude in this
business :).

-- 
-- Stephe

Re: Ada on Android?

[Stephen Leake]

jrmarino <dragonlace.cla@marino.st> writes:

> On Sep 6, 6:54 pm, Pascal Obry <pas...@obry.net> wrote:
>> Le 05/09/2011 22:15, onox a écrit :
>>
>> > You might be interested in checking the GNATDroid (Android 2.3+) cross-
>> > compiler for FreeBSD athttp://www.dragonlace.net/
>>
>> I haven't looked, but is there a script or instruction to build a cross
>> for Android somewhere?
>>
>> Pascal.
>>
>
> Pascal,
> Only the GNAT-AUX repository has the necessary patches to build GNAT
> for Android.  

This is ambiguous. Android is an operating system; you also need to
specify the machine when talking about cross compilers.

As far as I can tell, GNAT-AUX only targets the ARM machine.

> Unless somebody duplicates my work, any new android cross-compiler
> would have use this codebase.

I see no reason why the GNAT GPL 2011 jvm target should not work for
Android (except for the bugs I'm complaining about, of course. but they
are at a different level of detail :).

-- 
-- Stephe

Re: Ada on Android?

[jrmarino]

On Sep 8, 2:18 am, Stephen Leake <stephen_le...@stephe-leake.org>
wrote:
> jrmarino <dragonlace....@marino.st> writes:
> > On Sep 6, 6:54 pm, Pascal Obry <pas...@obry.net> wrote:
> >> Le 05/09/2011 22:15, onox a écrit :
>
> >> > You might be interested in checking the GNATDroid (Android 2.3+) cross-
> >> > compiler for FreeBSD athttp://www.dragonlace.net/
>
> >> I haven't looked, but is there a script or instruction to build a cross
> >> for Android somewhere?
>
> >> Pascal.
>
> > Pascal,
> > Only the GNAT-AUX repository has the necessary patches to build GNAT
> > for Android.  
>
> This is ambiguous. Android is an operating system; you also need to
> specify the machine when talking about cross compilers.
>
> As far as I can tell, GNAT-AUX only targets the ARM machine.
>
> > Unless somebody duplicates my work, any new android cross-compiler
> > would have use this codebase.
>
> I see no reason why the GNAT GPL 2011 jvm target should not work for
> Android (except for the bugs I'm complaining about, of course. but they
> are at a different level of detail :).
>
> --
> -- Stephe

Stephe, you're talking apples to oranges.
We're talking about building native Ada applications which (like
native C/C++ applications) could utilize the Android API for windows,
accelerator sensor access, etc.  The binding with those libraries
still need to be made, and you need to wrap in the xml manifests
described in the "nativeactivity" capability that was introduced with
Android 2.3.

You're talking about building the apps in the Java VM I think, and
that's just an entirely different approach.

GNAT-AUX specifically targets x86, x86_64 on four BSDs and Solaris,
and ARM on Android.  It will very likely work on other platforms
(namely Linux) and even other processors, but that is just a carryover
from gcc and it's not tested.
Stock GCC/GNAT can not be built for Android/ARM, although it should
work fine for Linux/ARM.

John

Re: Ada on Android?

[Brian Drummond]

On Wed, 07 Sep 2011 20:15:12 -0400, Stephen Leake wrote:

> Brian Drummond <brian@shapes.demon.co.uk> writes:

> Ada is supposed to be able to target the JVM; also being able to target
> ARM is an orthogonal issue. Targeting the ARM would be useful for
> compiling a new cryptographic library, for example. Totally unnecessary
> for building a music player.

Not necessary. Perhaps sufficient if you can bind to the API from native 
code and write native code callbacks (you can from C/C++ in Android 2.3, 
so presumably also Ada).

I am not suggestion there is anything wrong in targetting the JVM in Ada!
However, if that turns out to be problematic, native code could offer an 
alternative approach. Ideally, both will work.

> I'm don't understand what "SDK GUI Builder" you are talking about; I
> used Eclipse and the Android toolkit, as the Hello World tutorial says.

That is the one I meant. (I don't know how you installed it; for me, it 
came with the SDK. But it's some sort of Eclipse plugin)

> It is possible to do without the GUI builder by writing either Java or
> Ada code that constructs the GUI; we have the same choice in GtkAda. I'm
> going with the recommended approach to make sure I know what its
> advantages are before I give up on it.

Interesting. As far as I could see, we have to use XML (or the builder) 
to control layout. If you can do that in [Java/Ada] instead, that's very 
good news! I missed that. Any references to it, or sample projects?

>> A GTKAda binding to that mess would be nice ... (though probably
>> difficult to impossible)
> 
> Why would that be nice?

Just commonality with other platforms. I hear you about the mess in GTK 
underneath! 

If we can develop for Android and use the same product on other platforms 
(not just Windows), that would also be nice. Nicer, if the underlying 
windowing stuff is cleaner.

>> I'll report if/when I have a HelloWorld running.
> 
> I'm talking about the full Android windowing Hello World at
> http://developer.android.com/resources/tutorials/hello-world.html.
> _not_ just Ada.Text_IO.Put_line.

So am I; or rather, the exact equivalent "hello-jni" example from
http://developer.android.com/sdk/ndk/overview.html#samples
This ought to work on Android 1.5 and above. Then proceeding to the 
"native activity" and other samples, which will require 2.3.

For Ada.Text_IO.Put_line we are there already.

> You are way overly optimistic. But that's a necessary attitude in this
> business :).

Thanks!

- Brian

Re: Ada on Android?

[Stephen Leake]

Brian Drummond <brian@shapes.demon.co.uk> writes:

> On Wed, 07 Sep 2011 20:15:12 -0400, Stephen Leake wrote:
>
>> Ada is supposed to be able to target the JVM; also being able to target
>> ARM is an orthogonal issue. Targeting the ARM would be useful for
>> compiling a new cryptographic library, for example. Totally unnecessary
>> for building a music player.
>
> Not necessary. Perhaps sufficient if you can bind to the API from native 
> code and write native code callbacks (you can from C/C++ in Android 2.3, 
> so presumably also Ada).
>
> I am not suggestion there is anything wrong in targetting the JVM in Ada!
> However, if that turns out to be problematic, native code could offer an 
> alternative approach. Ideally, both will work.

Ah. I guess JNI is more complicated/complete than I had thought.
I'll have to read more about it. For example, there is now a
NativeActivity that allows writing a complete Activity in native code.

>> It is possible to do without the GUI builder by writing either Java or
>> Ada code that constructs the GUI; we have the same choice in GtkAda. I'm
>> going with the recommended approach to make sure I know what its
>> advantages are before I give up on it.
>
> Interesting. As far as I could see, we have to use XML (or the builder) 
> to control layout. If you can do that in [Java/Ada] instead, that's very 
> good news! I missed that. Any references to it, or sample projects?

I haven't tried it yet, but see
http://developer.android.com/reference/android/widget/LinearLayout.html
; you can specify a LinearLayout in code, and add things to it. 

There are reasons to use the XML; it keeps layout separate from the
rest of the code, so specifying portrait vs landscape vs widget is
cleaner. But similar separation could be achieved with appropriate
subprograms (or should I say "methods"? sigh).

Allowing users to specify layout at runtime might be a big advantage.

>>> A GTKAda binding to that mess would be nice ... (though probably
>>> difficult to impossible)
>> 
>> Why would that be nice?
>
> Just commonality with other platforms. I hear you about the mess in GTK 
> underneath! 
>
> If we can develop for Android and use the same product on other platforms 
> (not just Windows), that would also be nice. Nicer, if the underlying 
> windowing stuff is cleaner.

Yes, cross platform is a nice dream. I had high hopes for GtkAda for
that. At the moment, I think QtAda is better, but not by much.

I would like to port my Android music App to windows.

It may be that the Android windowing classes are built on top of Gtk,
in which case it _might_ be possible to port them to Windows. That would
be neat.

>>> I'll report if/when I have a HelloWorld running.
>> 
>> I'm talking about the full Android windowing Hello World at
>> http://developer.android.com/resources/tutorials/hello-world.html.
>> _not_ just Ada.Text_IO.Put_line.
>
> So am I; or rather, the exact equivalent "hello-jni" example from
> http://developer.android.com/sdk/ndk/overview.html#samples

Ok. I guess I should install the NDK and look at that.

-- 
-- Stephe