It requires Dolfin with Qt; it just reparents the plot window. Since the window (widget) is fetched from Qt directly, it does not require that the plot widget (or contents) are exported to Python.
The alternative implementation (exposing VTK actors instead) would probably require exposing those to Python. Regards, Joachim On 19 January 2015 at 18:37, Jan Blechta <[email protected]> wrote: > On Sat, 17 Jan 2015 15:18:50 +0100 > Joachim Berdal Haga <[email protected]> wrote: > > > I can provide a bit of history, at least. Originally the Qt support > > was meant to support embedding the plotting widget in external GUIs > > (meshbuilder, Dolfin GUI applications for teaching, etc.). However, it > > turned out that the VTK built-in window-manager interaction is (or > > was, at the time) really primitive, and it was impossible to get > > simple things like closing windows to work reliably across platforms. > > Hence, Qt was used also for the "simple" plot window. Since Qt is > > commonly installed already on workstations, and cluster-installations > > don't need a plotting window anyway, I considered it a reasonable > > dependency. (Rightly or wrongly.) > > > > Now, as Anders pointed out, these GUIs haven't materialized yet. One > > under-communicated aspect (because it wasn't considered back then) is > > that this can be done in Python, too, using PySide or PyQt. Just for > > fun I've attached a small demo that creates a Python GUI application > > for the Poisson demo, using PySide. Note: This is not meant to be > > included as a Dolfin demo, it is just thrown together to show that it > > can be done. > > Bummer, I haven't succeeded installing PySide using pip to try it. > > Does it need DOLFIN built with Qt? If not, it is then a good argument > for removing Qt dependency from DOLFIN. > > Jan > > > > > Benjamin: It is probably as easy as you suggest. The reason it is > > like it is now, it that we (or I) ended up using Qt for the simple > > plot window anyway, for stability reasons; and then it's even easier > > to embed the window in another application. > > > > Regards, > > Joachim. > > > > > > On 17 January 2015 at 09:12, Garth N. Wells <[email protected]> wrote: > > > > > > > > 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 > > >>>> >> > > >>>> >> _______________________________________________ > > >>>> >> fenics mailing list > > >>>> >> [email protected] > > >>>> >> http://fenicsproject.org/mailman/listinfo/fenics > > >>>> > > > >>>> > > > >>>> > _______________________________________________ > > >>>> > fenics mailing list > > >>>> > [email protected] > > >>>> > http://fenicsproject.org/mailman/listinfo/fenics > > >>>> > > > >>>> _______________________________________________ > > >>>> fenics mailing list > > >>>> [email protected] > > >>>> http://fenicsproject.org/mailman/listinfo/fenics > > >>>> > > >>> > > >>> _______________________________________________ > > >> fenics mailing list > > >> [email protected] > > >> http://fenicsproject.org/mailman/listinfo/fenics > > >> > > > > > > > >
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