[Pharo-dev] Questions about Athens

Igor Stasenko siguctua at gmail.com
Thu Oct 31 15:29:17 EDT 2013


On 31 October 2013 18:24, kilon alios <kilon.alios at gmail.com> wrote:

> I created a new subject
>
> About the problem to recreate it all it takes is a demo := AthensDemoMorph
> new openInWorld . It opens the morph with the Athens grey box, I save the
> image , close pharo, open pharo which reloads the image automagically and
> BOOM Red Box of Doom :) My other tries also are based on AthensDemoMorph
> since I cant find documentation to do things differently.
>
>
That one is bad, it does not having session management code.
Perhaps because the code there was authored before i figured what is most
convenient pattern to deal with it, neither i thought about that at all,
because it was
too early to think about it. At that stage i was more concerned about that
framework
is capable of rendering stuff correctly. (see my other reply about that).



> So lets get to the questions
>
> 1) You say you have morphs using Athens that don't have this problem, care
> to explain further ?
>
> yes, there is number of morphs which correctly implement session-aware
resource management, which you need when working with surfaces.
AthensSceneView, AthensWrapMorph

The problem is that right now it is a little incursions (since Athens does
not completely
replaces old Canvas and runs in parallel to it), and there is no globals,
like Display
which manages that.

This code had to be added at one day, but not before we figure, how we can
deliver
rendered data directly to OS-level window bypassing Form(s) and unnecessary
bit copying here and there between number of double-triple-quadruple
buffering which stands between Morphic and OS-level screen, which greatly
hinders the screen update performance. (or at least figure our migration
plan/path).

But for that we also must cut out parts in VM and move responsibility for
creating
OS-level window(s) into image, not VM.
The limitations, which we currently having in VM greatly cripples the
number of
choices of what can be done using Pharo for making desktop-level
application.
But it is more general problem, and there's nothing in Athens to blame for
it.

2) How do I recreate automatically those surfaces ?
>
> 3) Do I need to instruct the image on load to reinitialize those objects ?
>
> 4) If yes How I do that ?
>
> see how i did that in AthensSceneView, AthensWrapMorph


> You say its a major problem but yet its not an Athens bug.  I know this is
> has to do with how image saves live objects and that NB calls are not part
> of the image hence creating the problem.
>
> 5) Are there ways to avoid the problem ?
>
> yes, use Smalltalk session object to check if session is changed before
any attempt of using external resource(s).


> 6) Also why there is a Red Box of Doom in the first place ?
>
> 7) Why the debugger is not triggered as it should be ?
>
> It is a general feature of Morphic: if there's an error during morph's
drawing
it renders it as red box, but not opens a debugger.
because opening debugger implies that you will need to render debugger
window,
but if that code raising an error, you will enter endless recursion.

If you don't like it, you can disable it in
Morph>>fullDrawOn: aCanvas
(and then try to put a mistake in any morph's rendering code.. but don't
say i didn't warned you ;)

8) Is that critical a failure of Morphic ?
>
>
It is not a failure, the red box is the only sane way how to keep things
running,
even if there's error(s) in code. But sometimes even that doesn't helps.
Other choice would be to just leave to OS, because at that stage UI will be
unresponsive anyways, but that will be even worse, isn't?


> 9) Why Athens even though is based largely on Cairo , and taking into
> consideration the intention to extend to other graphical interfaces, not
> following the Cairo design more closely so we can use the Cairo tutorials ?
>
> The biggest source for design choices is not Cairo. But OpenVG standard.
Cairo was easy to reach, low-hanging fruit which we grasp.
A more expanded answer as for why Athens is not copy-paste of Cairo,
you can read here:
http://computeradventures.wordpress.com/2012/03/07/athens-a-first-babysteps/

[[
In other words, give me 1 week, a lump sum of money, and after 2 weeks [image:
;)] i will deliver you a binding to any C library you want. But do not
expect that it will be much easier to use it, only because you can access
it in smalltalk. This is because exposing a non-object oriented library in
smalltalk does not automagically makes it by a bit more object oriented,
especially in terms of smalltalk, not in terms of C++ [image: :)] .
]]



10) Is the Cairo design so prohibiting / limiting for Athens ? Does Cairo
> do things so differently than other vector based libraries ?
>
>
Most of them providing more or less same set of features.
But each of them has own API and own idiosyncrasies to deal with,
and Athens here to serve for hiding unnecessary details from users and
provide a consistent object-oriented API.


> 11) How important is Athens to Pharo community , meaning further bug
> fixes, improvements , tutorials etc ? I hear there is an intention to
> gradual move Morphic to it. Is this true ?
>
> Yes, it is our future.


> I really like Athens, I am asking all these questions because I need to
> make a fast decision whether I will continue to use Pharo or not for my
> project. Learning OpenGL and using NBOpenGL produced zero results for me. I
> was not even able to create a single triangle. My gpu driver because of
> Macos gave me close to zero errors, and Red Box of Doom made it impossible
> to debug opengl problems. In short close to zero error reporting made it a
> no go for me.
>
>
Sounds like you surrendered too quickly. :)
I know multiple people who managed to do things with it,
like importing 3d models and rendering them.
But sure thing, it is not easy and requires a lot of effort and broad
knowledge in multiple areas and abilities to learn & search for examples
and docs and
understanding the mechanics behind everything.



> So I fall back at much simpler solutions because I want to create my own
> GUI API. I see several solutions for this
>
> 1) Pharo Athens
> 2) Amber SVG / WebGL based Vector libs like Pixi /  Athens / HTML5 + CSS
> 3) Python + PyQT + QT
>
> I rather stay with Pharo. But I already wasted months of doing nothing and
> going nowhere with NBOpenGL , I am tried of moving in circles. I am not
> frustrated cause I knew when I tried that OpenGL was very hard ( I was
> warned by several opengl people ) so failure was always an option , but I
> can no longer justify wasting my time getting nowhere.
>
> you can ask Alex, who has working examples of opengl. Roassal 3D.



> I dont need much from a graphic lib all I need is
>
> a) Stability . If it crashes regularly its no good
>
> b) Speed, if moving graphic elements around slows down (anything above
> 20%)  dual cores , its no good
>
> c) Basic Feature set  like , lines, curves , circles and ellipses ,
> display of raster graphics, simple animations , import export of graphic
> formats, png , jpg and svg is enough.
>
> Looks like Athens satisfies b and c , I am not so sure about a.
>
>
I dealing with Athens for... ?last year? almost every day during my work..
don't have much problems here. And that would be my top-priority taks, if
it would be a problem, because it would be blocking my own work.



> I am trying to understand Athens code from reading it, once again I am a
> big failure at understanding code.
>
> ask questions. I will gladly help understanding.


> So is there any hope for someone like me , that he is not a very good
> coder, he is new to Pharo and he has a simple mind to use Athens to make a
> basic GUI API ?
>
> Definitely yes :)


> On Thu, Oct 31, 2013 at 6:07 PM, Igor Stasenko <siguctua at gmail.com> wrote:
>
>>
>> On 31 October 2013 16:40, kilon alios <kilon.alios at gmail.com> wrote:
>>
>>> save the image while the morph is displayed, reload the image and in its
>>> place there is the big red box with the yellow X , reporting an error with
>>> Athens. I have reproduced the error on Windows too with the Athens
>>> examples. I assumed my explanation was clear , I hope its clear now.
>>>
>>>
>> no. not clear. which morph? what class, how you using it etc.
>> I have morphs which using Athens for drawing and i can save and load
>> image back and i don't have red squares of death.
>>
>>
>>> This means that its impossible to save an image with a morph using
>>> Athens displaying and have it reload back when the image is reloaded.
>>>
>>> The athens-surface, especially cairo surface is valid only within a
>> single session.
>> if you boot new image, you must recreate (or stop using) surface you used
>> in previous session.
>> Otherwise you will have red box of doom.
>>
>> And while i agree that this is pretty major problem (in terms of making
>> your morph to be session-aware
>> and in terms of managing external resources) i am far from calling it a
>> bug of Athens of any kind per se.
>>
>>
>>
>>>  On Thu, Oct 31, 2013 at 5:05 PM, Stéphane Ducasse <
>>> stephane.ducasse at inria.fr> wrote:
>>>
>>>>
>>>> On Oct 31, 2013, at 9:55 AM, kilon alios <kilon.alios at gmail.com> wrote:
>>>>
>>>> yes I am aware of the examples already, I am learning from them. Please
>>>> note I have found a bug with Athens, which looks to me pretty major. If I
>>>> save a morph using Athens
>>>>
>>>>
>>>> what do you mean save a morph
>>>>
>>>> and reload the image,
>>>>
>>>>
>>>> what do you mean?
>>>>
>>>>
>>>> I see the red box of doom. For example trying your example from
>>>> stackoverflow. Are you aware of this bug ?
>>>>
>>>>
>>>> On Thu, Oct 31, 2013 at 2:43 AM, Igor Stasenko <siguctua at gmail.com>wrote:
>>>>
>>>>> ah, yes , there's also examples in
>>>>> Athens-Examples package.
>>>>>
>>>>>
>>>>> On 31 October 2013 01:30, Igor Stasenko <siguctua at gmail.com> wrote:
>>>>>
>>>>>>
>>>>>> On 30 October 2013 23:02, kilon alios <kilon.alios at gmail.com> wrote:
>>>>>>
>>>>>>> well I just asked if there is any kind of Documentation about Athens
>>>>>>> . Or should I just read the code and ask questions ?
>>>>>>>
>>>>>>>
>>>>>> the main source of documentation right now is class comments
>>>>>> and tutorial.
>>>>>> I've spent quite of a time commenting the central classes of athens,
>>>>>> hope that's helpful.
>>>>>> Of course this does not replacement for a well written docu, and that
>>>>>> needs to be done.
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> On Wed, Oct 30, 2013 at 11:51 PM, Igor Stasenko <siguctua at gmail.com>wrote:
>>>>>>>
>>>>>>>> i hope you satisfied with my answer.
>>>>>>>> you welcome to ask more, if you not :)
>>>>>>>>
>>>>>>>>
>>>>>>>> On 30 October 2013 22:32, dimitris chloupis <thekilon at yahoo.co.uk>wrote:
>>>>>>>>
>>>>>>>>>
>>>>>>>>> http://stackoverflow.com/questions/19694197/how-to-create-lines-with-athens
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Best regards,
>>>>>>>> Igor Stasenko.
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Best regards,
>>>>>> Igor Stasenko.
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Best regards,
>>>>> Igor Stasenko.
>>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>> --
>> Best regards,
>> Igor Stasenko.
>>
>
>


-- 
Best regards,
Igor Stasenko.
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