[nvda-addons] Re: Developing Addons - The best way to get started?
- From: "Damien Sykes-Pendleton" <damien@xxxxxxxxxxxxxxxxxxxx>
- To: <nvda-addons@xxxxxxxxxxxxx>
- Date: Tue, 12 Apr 2016 18:30:32 +0100
Hi,
One thing I did manage to do is to apply the first example app module example
to the application I want to change rather than Notepad, so I know I’m in the
right direction there. What also helps is because this application is much
bigger I was able to see it in action more – the focus beeping one. Even if I
so much as moved the cursor, pressed Tab, went into menus etc, it beeped all
the time, so not sure if that’s to do with keyboard input or whatever. If so
then that’s not the issue. Key commands are being recognised fine, it’s just
what is being spoken.
Thanks.
Kind regards,
Damien.
From: derek riemer
Sent: Tuesday, April 12, 2016 5:59 PM
To: nvda-addons@xxxxxxxxxxxxx
Subject: [nvda-addons] Re: Developing Addons - The best way to get started?
Hi,
It really depends what you intend your add-on to do. Do you think some code
should execute? Test it by either importing logHandler, and logging with one of
the methods there, or use tones.beep to beep as the first thing that happens in
that function. Also, it shouldn't play the error sound unless you are running
master or next. Look for errors in your log, test your add-on with master or
next, or go to the NVDA python console and run >>> import versionInfo
versionInfo.isTestVersion = True
Then the sound should happen. You could write an add-on to set this to true at
NVDA Startup (Hint) just putting that in a python file in the globalPlugins
folder should do it. Do not be afraid to ask us questions if you have a
hypothesis about some control, and a way in which you are trying to make it
work. I promise you, there are no dumb questions here. If it is a script, be
sure to bind it to a gesture. If it is one of the meriad of events, then you
may very well just have to play with trying multiple events until you find the
right one. That's where making NVDA play different tones for different events
is super helpful.
HTH
On 4/12/2016 10:32 AM, Damien Sykes-Pendleton wrote:
Hi there,
OK. So I now have a fair grasp of the Python language. Luckily because I’ve
tried so many times before and failed it was just a case of refreshing my
memory as to what different things meant, and reading more in-depth those
things that I didn’t understand. I think it kind of helped that the easy stuff
was, well, easy, and the harder stuff I have covered before in other languages,
but they are termed or written differently. I think one thing that confused me
a lot when I started out is how all classes inherit from object, when an
instance of a class is also called an object. Wow...Deep stuff.
Also, this time, I have seen Python code in action, having installed Python
itself. It’s odd, but I think that helped me more than I realised it would.
Reading code and then seeing it work seems to impress things more firmly into
memory (Human, that is).
Now that I’ve done that, it seems when I tried this before that the thing I
was struggling with most were NVDA concepts. There were no errors triggered (At
least I don’t think), but the addon itself that I created didn’t work.
Is there anything else I need to look at? The development guide has become a
little easier in some respects but I’m still in the dark about others, for
instance application controls, accessing them, reading them, event triggers,
etc.
Thanks.
Kind regards,
Damien.
From: derek riemer
Sent: Friday, April 08, 2016 6:17 PM
To: nvda-addons@xxxxxxxxxxxxx
Subject: [nvda-addons] Re: Developing Addons - The best way to get started?
Hi,
Please feel free to ask us (especially me) anyy development questions you
have. I can try to help. Please believe me when I say I know where you are
coming from, I had to learn all this myself, and it is damn hard. Even if you
ask "This button is not speaking, How should I try to make it speak?" I will
try to walk you in the right direction.
On 4/8/2016 5:56 AM, Damien Sykes-Pendleton wrote:
Hi James,
Again. This proves just how much, or little, knowledge I have on this
subject. I always assumed that the information that NVDA uses to evaluate the
functionality or purpose of a control was through the Windows API. When I wrote
my first addon that didn't involve copying and pasting from an example, it was
to read content that NVDA didn't recognise on its own for whatever reason, that
other screen readers did. This didn't work. My theory for this is that I was
pretty much guessing what I had to do to get it to work, and of course that is
not the way to understand your own code. It helps to understand what your code
needs to do, something of which I understood very little, if not nothing at
all. If you can't understand that, you need to be able to understand what you
want to do. Although I know what I want to do in terms of functionality,
translating that into code is very difficult, given that I don't know about all
the underlying structures such as in-depth control information (ID, handle,
class etc), NVDA objects, accessibility platforms, the list goes on and on.
As for learning Python itself, this is not so much the problem as
remembering every single thing I'm reading. When I look at a Python tutorial,
I'm thinking, yes this makes sense. Sounds good to me. Oh wow, I've finished
the tutorial. Let's go back to addons. Oh wait, what did the tutorial say about
this? I don't remember that part...Look back at the tutorial. Oh, it's not in
here. This must be an NVDA specific reference. Either that, or, Ah yes, I
remember this now. Now how was the addon guide referencing this?
I'm trying to explain it the best way I can, because there isn't one
specific example or situation that I can pinpoint without referencing something
else, it's all linked, hence the massive confusion which, if we're talking
code, is making my brain go into an infinite loop.
Kind regards,
Damien.
-----Original Message----- From: James Scholes
Sent: Friday, April 08, 2016 12:25 PM
To: nvda-addons@xxxxxxxxxxxxx
Subject: [nvda-addons] Re: Developing Addons - The best way to get started?
Replies inline.
Damien Sykes-Pendleton wrote:
Well if we're constraining ourselves to the facts, I can only really
say what I have said before, in that the developer guide assumes a
good working knowledge of Python and NVDA's internal workings,
neither of which I feel I have enough of to really get going.
First, tackle Python. You need a good, working knowledge of the
language to write NVDA add-ons. This will never change, no matter how
much documentation is written. Create some small Python projects which
make use of object-oriented programming, inheritance, wxPython.
It is incredibly important to understand that creating NVDA add-ons is
not at all like writing JAWS scripts. With JAWS scripting, the language
is proprietary and the creators of that language decide in advance what
functionality you have access to. NVDA not only gives you the full
power of the Python language, but also lets you write code which runs in
the same environment as NVDA's core, meaning that you can literally do
whatever you like, only constrained by your imagination and knowledge.
Naturally, this provides a lot of room for error, so NVDA add-on writing
often comes with a lot of responsibility. That is why there is a
higher barrier to entry. It's up to you to decide whether that barrier
is worth scaling or not. But nobody, on this list or otherwise,
will ever be able to create documentation that explains every possible
aspect of creating NVDA add-ons. Having said that, the community has
created some extra documentation, which I will leave it up to them to
share.
I have looked into Python, both on the official language tutorial
and from Learn Python the Hard Way. Although these are both good
resources, they are also very extensive to the point that by the
time I have read them and gone back to the developer guide, I'm
trying to conceptualise everything else into Python terms rather than
NVDA terms
I'm not entirely sure what you mean here. NVDA is Python. Granted, to
write a good add-on, you have to be aware of some of NVDA's internals,
but really, you need to give us examples of what you're trying to do and
why it's posing a problem. If you have a good understanding of Python
as I said above, writing NVDA add-on boilerplate will be easy.
some of which can be done but easily forgotten, or others which can't
be done at all.
Again, I have no idea what you mean. What Python features,
functionality or concepts are you having difficulty translating into
valid concepts to be used in an NVDA add-on?
Then, as I have also said before, there
is the vagueness of references, such as "Refer to the NVDA code
documentation". I cannot find this documentation anywhere, even in
the NVDA source code.
If you check out the NVDA source code and read the accompanying readme
files, you will see instructions on generating the NVDA code
documentation. You can also browse an online copy, although I don't
think it's updated on a regular basis, at:
https://files.derekriemer.com/nvda/module-tree.html ;
Honestly though, I think most NVDA developers will tell you that reading
the code itself is usually better than the documentation. If you're
hoping that the code documentation will shine a light on everything that
has hitherto seemed confusing, you'll be seriously disappointed. The
code documentation is constructed from Python docstrings. It's a terse
reference, not a guide.
Even so, I doubt I'd be able to glean much
from it, since NVDA has a lot of in-depth interaction with the
operating system which, when it comes to development, I know hardly
anything about the workings of. This then also adds the Windows API
to my reference list, and now I feel like I am on a road of
information overload.
Any portions of the Windows API that are used by NVDA have already been
wrapped as simple Python functions for use in higher level abstractions.
Unless you need to use a part of it that hasn't already been defined as
such, you don't need to understand the ins and outs of that.
Additionally, it's highly unlikely that, for your first add-ons, you'll
even need to use such functionality. Rather, you'll interact with the
abstractions that NVDA provides.
To sum up:
1. Learn Python. If you don't know the language, if you can't write
scripts or small programs in it, you will have a hard time writing code
for NVDA.
2. Get familiar with reading other people's Python code. You'll be
doing a lot of that if you want to create high quality add-ons.
3. Give us examples of things you're finding hard. We don't need an
article, we just need you to explain what you don't understand so we can
point you in the right direction.
4. Don't run before you can walk. If you're struggling with how to
create the most basic of add-ons, the Windows API isn't even a distant
concern.
--
------------------------------------------------------------------------------
Derek Riemer
a.. Department of computer science, third year undergraduate student.
b.. Proud user of the NVDA screen reader.
c.. Open source enthusiast.
d.. Member of Bridge Cu
e.. Avid skiier.
Websites:
Honors portfolio
Awesome little hand built weather app!
mailto:derek.riemer@xxxxxxxxxxxx ;
Phone: (303) 906-2194
--
--------------------------------------------------------------------------------
Derek Riemer
a.. Department of computer science, third year undergraduate student.
b.. Proud user of the NVDA screen reader.
c.. Open source enthusiast.
d.. Member of Bridge Cu
e.. Avid skiier.
Websites:
Honors portfolio
Awesome little hand built weather app!
mailto:derek.riemer@xxxxxxxxxxxx ;
Phone: (303) 906-2194
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