On Fri, 16 Jan, 2015 at 11:06 PM, Benjamin Kehlet <[email protected]>
wrote:
2015-01-16 16:00 GMT+01:00 Jan Blechta <[email protected]>:
On Fri, 16 Jan 2015 12:55:35 +0100
Benjamin Kehlet <[email protected]> wrote:
I agree with Garth and Jan that Qt should be removed. The Qt
I didn't say whether Qt should be removed.
Ah, I see that now. Sorry.
I don't think that there's a
strong need to remove it unless it requires in a future any
maintenance
which nobody wants to do.
With a removal, VTK plots will loose a capability of closing a
window.
I didn't know that. What functionality is it that the Qt-based
plotting provides? Closing plotting windows programmatically?
functionality was added to make it possible to reuse the plotting
functionality in third party Qt applications, but this is
(apparently)
not used at all. The plotting code should really be kept as
minimal as
possible.
If someone wants to embed the plots in Qt (or another GUI
framework),
it is better to expose the what is needed to do that outside of
Dolfin. (I haven't looked into this, but it may be possible
already by
using VTKWindowOutputStage).
This is exactly what is done. There are few #ifdef HAS_QVTK
switching
between vtkRenderWindowInteractor implementation and QVTKWidget
implementation. If we remove Qt, QVTK (I'm not sure how coupled are
these two dependencies; anyway DOLFIN requires both or none) then
this
interface will be gone.
Code in plot-qt demo is just application using this interface.
My point was that I imagine it would be pretty simple to adjust the
interface so that applications can do this outside Dolfin. An
application could maybe do somethin like this:
* Create a dolfin::VTKPlotter object.
* Grab a reference to the vtkRenderWindow object from the
dolfin::VTKPlotter object an connect it to whatever GUI framework it
uses.
* Plot the dolfin object to the dolfin::VTKPlotter.
or (a bit more low level)
* Create a dolfin::GenericVTKPlottable object from the dolfin object
it would like to plot.
* Grab a reference to the vtkActor object from the
GenericVTKPlottable.
In both cases the plotting code in Dolfin is reused, but Dolfin is
unaware of the GUI framework and linking, find_package() etc. is done
(and maintained) on the application side.
Joachim: Shout if I'm missing anything essential here!
Finally, the apparent confusion of new users by enormous number of
useless dependencies is rather problem of documentation. There
should
be clearly stated:
1. What is dependency for.
2. Which dependencies are recommended to have useful DOLFIN.
Good point, but maintaining documentation also requires work. This is
maintenance that no one is eager to do and should be minimized.
I don't think documentation is the solution. It helps, but if someone
needs to make a decision at that level before they can get started it's
already too late. A new user is unlikely to understand the full
implications of having or not having an optional dependency, and err on
the side of caution and enable it. I know I do.
Cutting dependencies that offer little reduces maintenance, simplifies
testing (fewer combinations to consider) and simplifies installation
approaches like Hashdist and containers/VMs that have fewer
dependencies to worry about supporting.
Garth
Benjamin
Jan
Regards
Benjamin
2015-01-15 21:33 GMT+01:00 Anders Logg <[email protected]>:
> I would vote for keeping the Qt functionality for a while longer.
> It was added in case we would later needed (for users that want
to
> wrap DOLFIN plots inside applications).
>
> But I agree with needing to reduce the number of dependencies.
>
> --
> Anders
>
>
> Thu Jan 15 2015 at 5:28:36 PM skrev Garth N. Wells
> <[email protected]>:
>>
>> It would be nice if we can reduce the number of optional
>> dependencies in DOLFIN - it's confusing for users to know which
>> optional dependencies they really should have, e.g. PETSc, and
>> which they very likely do not need, e.g. QT.
>>
>> Garth
>>
>> On Thu, 15 Jan, 2015 at 3:18 PM, Jan Blechta
>> <[email protected]> wrote:
>> > Garth suggested removing Qt dependency. Here are some facts
to be
>> > considered
>> >
>> > 1. DOLFIN links to libQtCore, libQtGui
>> > - cost:
>> > - linking problems, recently on support mailing list
but
>> > rather rare
>> > - size of libdolfin.so, Release build type, with
>> > everything except PaStiX and slepc4py:
>> > - with Qt 8M
>> > - without Qt 8M
>> > - memory footprint after "from dolfin import *"
>> > VIRT RES SHR
>> > - with Qt 751M 101M 39M
>> > - without Qt 679M 97M 48M
>> > This is rather negligible.
>> > - advantages:
>> > - Plot window can be closed!
>> >
>> > 2. there is plot-qt demo demonstrating how interactive widget
>> > allowing
>> > - basically what usual VTK plotting does
>> > - plus reporting some numbers on mouse hover
>> > - plus marking cells by clicking on them
>> > for the prize of 252 lines of C++ code (without comments
and
>> > blank lines). According to git log in that directory, it seems
>> > that the code is not fragile and did not need maintenance
nearly
>> > at all so far.
>> >
>> > Similarly, Qt, QVTK related code in dolfin/plot is rather
>> > minimal and does not require much maintenance. But this isn't
so
>> > straightforward to check.
>> >
>> > Jan
>>
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