Develop Reference

Creating a C++ Qt Gui for a Python logic

I was presented with a Python logic for which I need to create a GUI. I want to use Qt for that purpose and ideally I would like to program it in C++, without using the Qt Creator.
What are recommended ways of combining a C++ Qt GUI and a Python logic, perhaps with a controlling layer which is either in Python or C++?
Due to prior research, I'm aware of certain tools like PySide, PythonQt, SWIG, Shiboken and others (although I haven't used them so far) and that it is very simple to import *.ui files into Python, but the number of possible ways is a bit overwhelming and I could not come up with a "good solution" so far.
Ideally, I would not use Qt Designer, but create the GUI (windows, custom widgets, helper classes etc) by hand, combine them into one or few classes which I expose to a Python/C++ controlling layer (by wrappers? DLL?) which manages the communication between GUI and logic.
How can I achieve this?
A short version of this question might just be: How can I use a Qt C++ GUI with a Python logic?

You can create your GUI application using qt c++ and wrap controler logic written in a python api embedding the python api.
https://docs.python.org/2/extending/embedding.html
But if you have many methods that will be boring to do and you may have some memory leaks if not well written in th c++ side.
Another solution may be using rpc calls to a python api using a webservice (rest api/json rpc ....Etc...). Qt application is client of a python rest api.
like this you split the c code from the python one. You can do that using json rpc calls , or other apis,like jcon (https://github.com/joncol/jcon-cpp).
You will too be able to find python and QT xml rpc api able to talk together.
swig (http://swig.org) may have some capability , but it is better used in the other way : calling c func from python

Framework for paint program

I've decided to start working on a personal project, attempting to develop a cross platform, MSPaint like app. Oddly enough, I find mspaint is one of the applications I miss the most on Linux or OS X, so I want to try to make something similar. Tuxpaint, mtpaint, gpaint, etc. are all old and inactive and ugly. I don't want to make GIMP, just the basics, similar in features to MS Paint.
I'm thinking of doing it in python with the pygtk toolkit, but I was interested to hear your suggestions. Would C/C++ be a better choice, or even C# (gasp!) with mono? How about using Qt as opposed to GTK, or maybe some other fancy library I don't know about (Please, not FLTK!). I'd be curious to hear your thoughts.
Thanks!

Qt's canvas object (or its newer replacement QGraphicsView) can do pretty cool things. Whether you choose C++ or python is a matter of personal choice, as Qt is supported in both languages. For a simple project like this I'd choose python because killer performance is not much of an issue, and it will be much easier to write.
Another thing to look into is making this app web based with HTML5's canvas object and Javascript. It can be surprisingly robust, and anything that can be put on the cloud is a win in most cases.

If you decide to go with Python (which would be my choice because it's such a simple language), then TkInter is considered the de-facto standard GUI package. That link should send you to some excellent starting references for TkInter, although I also really like Not_a_Golfer's suggestion of an HTML5 web-app.

Short: You can use both, no third party library is guaranteed to be distributed with all major distributions.
Long:
Gtk+ vs. Qt
What do you want incorporate into your application. If it is just selecting a brush, selecting color you could pretty much use any gui toolkit.
If you are going to run it as a web-based tool, Gtk+ has an html5 backend renderer (I don't know about Qt)
A sidenote:
I recommend to use the toolkit's native programming language (gtk+ C, Qt C++) - if you don't, you will suffer from delays with bugfixes, generally more bugs and delayed releases, though for that case it shouldn't really matter.
Everything else boils down to personal preferences and there already exist some questions to tackling that issue.

if you are using qt,you can use QtitanRibbon

High(er) level frameworks that wrap Tkinter/ttk

Curious if there are any higher level frameworks that attempt to wrap Tkinter? For example, wxPython is wrapped by the Dabo framework (http://dabodev.com/) and PythonCard.
Motivation: We've recently moved to Python 2.7 (Windows) and are very impressed with the new ttk (Tile) support which allows one to build professional quality, platform native GUI's using the built-in Tkinter framework. In the past we would have used wxPython to create simple GUI interfaces for our command line utilities, but we're re-thinking this strategy in favor of using Tkinter/ttk for these use cases.
We're new to Tkinter (coming from wxPython) and while Tkinter/ttk seem to be simple to use, there seems to be a lot of repeated boilerplate code that we're writing. Before we try to wrap up some of our code in a home made set of classes, I want to make sure that we're not re-inventing the wheel.

Probably a little bit late for you. But I've just released a tkinter framework in beta called tKroopy. Which aims to provide a means for switching between dialogs and provide some higher level widgets, like easily displaying tabulated data.
It was designed for building lots of small to medium applications and grouping them together in a single application, but there is no reason why you couldn't use it to build a single large scale application too.
https://github.com/tKroopy/tkroopy

The only one I knew about seems quite stale, Python megawidgets.
You can find a list of others on the Tkinter wiki.

tkRAD supports python 2 and 3 and looks mature
https://pypi.python.org/pypi/tkRAD/1.6.5

Is there a Python library that allows to build user interfaces without writing much code?

I am writing editing front ends in Python since several years now, and I am fed up with micromanaging every UI detail of a window or dialog every single time.
Is there a technology that allows me to, say, specify the relations between a GTK+ Glade-designed interface and the tables and records of an SQLite database to do all the middle man work? It should spare me the work of manually writing event handlers, input evaluators and view updates.
The technologies in question are just examples, but I want to stick with Python as far as possible.

Besides the ones already mentioned I can add:
Kiwi
uxpython
pygtk
treethon
I've never used any of them so have no recommendations but, for what it's worth, I have used at least 2 complex programs built directly on pygtk that worked in both Windows and Linux.
I think Kiwi is the only one of these with baked in support for db (through interface with SQLAlchemy, SQLObject, or Storm) but I would be surprised if you couldn't use one of those ORM's inside any of the other frameworks.

PyQt and its models can automate some of these tasks for you (to some amount off course, e.g. filling widgets with data from a database and handling most of the widgets behaviour, buffering etc.).
If you want a more object-oriented approach to handling SQL you could look into an ORM-oriented solution (for example SQLAlchemy).

Dabo is built on top of wxPython, so you may not prefer it, but it's designed to make it easy to tie a GUI to a database, so I'd recommend you check it out if you haven't already. In particular, it's got good facilities for tying widgets to data, and handling a lot of the common cases of GUI development.

wxGlade may help, although I haven't used it myself so I don't speak from experience.
Boa Constructor apparently has a wxPython GUI builder in it, and there is also PythonCard, though development on these two projects seems to have stalled.

Traits might be a good option for you.
http://code.enthought.com/projects/traits/docs/html/TUIUG/index.html
AS simple as it is to map a UI to an object, it doesn't seem too far fetched to incorporate SQLAlchemy for persistence.

There is a good book on wxPython, "wxPython in Action", which can't be said for some of the other solutions. No knock on the others. I've had success developing with wxPython in the past and it comes with a great set of demo applications with source code from which you can borrow liberally.
The best UI designer I found for wxPython applications is a commercial one, Anthemion DialogBlocks. It's by one of the wxPython programmers and is worth the money. Other solutions for UI design include wxGlade (I found it usable but not featureful) and Boa Constructor (haven't used it). Wing IDE might also have one. Stani's Python Editor bundles wxGlade, I believe. There are a lot of other projects that don't really work or are fairly old.
As far as SQL automation goes, as another answerer says, I'd look at SQL alchemy, but the learning curve for a small application might be too much and you'd be better off just going straight to odbc. The best odbc api is the one used by Django, pyodbc.
It's been a while since I developed with these tools, so there may be something newer for each, but at the time these were definitely the best of breed in my opinion.

I had lots of success with wxPython, but that was some years ago now and there may be better new solutions...

Ok this is an unconventional solution but write yourself a code generator. I have done this several times using Mako. So in my case I auto inspect a table which columns it contains and types and generate classes from that. It's more work upfront but does exactly what you want and is reusable in subsequent projects.

Cross-platform gui toolkit for deploying Python applications

Building on:
http://www.reddit.com/r/Python/comments/7v5ra/whats_your_favorite_gui_toolkit_and_why/
Merits:
1 - ease of design / integration - learning curve
2 - support / availability for *nix, Windows, Mac, extra points for native l&f, support for mobile or web
3 - pythonic API
4 - quality of documentation - I want to do something a bit more complicated, now what?
5 - light weight packaging so it's not necessary to include a full installer (py2exe, py2app would ideally work as-is and not generate a gazillion MBs file)
6 - licensing
7 - others? (specify)
Contenders:
1 - tkinter, as currently supported (as of 2.6, 3.0)
2 - pyttk library
3 - pyGTK
4 - pyQt
5 - wxPython
6 - HTML-CGI via Python-based framework (Django, Turbogears, web.py, Pylons...) or Paste
7 - others? (specify)

Please don't hesitate to expand this answer.
Tkinter
Tkinter is the toolkit that comes with python. That means you already have everything you need to write a GUI. What that also means is that if you choose to distribute your program, most likely everyone else already has what they need to run your program.
Tkinter is mature and stable, and is (at least arguably) quite easy to use.I found it easier to use than wxPython, but obviously that's somewhat subjective.
Tkinter gets a bad rap for looking ugly and out of date. While it's true that it's easy to create ugly GUIs with Tkinter, it's also pretty easy to create nice looking GUIs. Tkinter doesn't hold your hand, but it doesn't much get in the way, either. Tkinter looks best on the Mac and Windows since it uses native widgets there, but it looks OK on linux, too.
The other point about the look of Tkinter is that, for the most part, look isn't as important as people make it out to be. Most applications written with toolkits such as Tkinter, wxPython, PyQT, etc are special-purpose applications. For the types of applications these toolkits are used for, usability trumps looks. If the look of the application is important, it's easy enough to polish up a Tkinter application.
Tkinter has some features that other toolkits don't come close to matching. Variable traces, named fonts, geometry (layout) managers, and the way Tkinter processes events are still the standard to which other toolkits should be judged.
On the downside, Tkinter is a wrapper around a Tcl interpreter that runs inside python. This is mostly invisible to anyone developing with Tkinter, but it sometimes results in error messages that expose this architecture. You'll get an error complaining about a widget with a name like ".1245485.67345" which will make almost no sense to anyone unless you're also familiar with how Tcl/tk works.
Another downside is that Tkinter doesn't have as many pre-built widgets as wxPython. The hierarchical tree widget in Tkinter is a little weak, for example, and there's no built-in table widget. On the other hand, Tkinter's canvas and text widgets are extremely powerful and easy to use. For most types of applications you will write, however, you'll have everything you need. Just don't expect to replicate Microsoft Word or Photoshop with Tkinter.
I don't know what the license is for Tkinter, I assume the same as for python as a whole. Tcl/tk has a BSD-style license.
PyQt
It's build on top of Qt, a C++ framework. It's quite advanced and has some good tools like the Qt Designer to design your applications. You should be aware though, that it doesn't feel like Python 100%, but close to it. The documentation is excellent
This framework is really good. It's being actively developed by Trolltech, who is owned by Nokia. The bindings for Python are developed by Riverbank.
PyQt is available under the GPL license or a commercial one. The price of a riverbank PyQt license is about 400 euro per developer.
Qt is not only a GUI-framework but has a lot of other classes too, one can create an application by just using Qt classes. (Like SQL, networking, scripting, …)
Qt used to emulate GUI elements on every platform but now uses native styles of the platforms (although not native GUI toolkits): see the documentation for Mac OS X and the windows XP style
Packaging is as simple as running py2exe or pyInstaller. The content of my PyQt app looks like this on windows (I have used InnoSetup on top of it for proper installation):
pyticroque.exe PyQt4.QtGui.pyd unicodedata.pyd
MSVCP71.dll PyQt4._qt.pyd unins000.dat
MSVCR71.dll python25.dll unins000.exe
PyQt4.QtCore.pyd sip.pyd _socket.pyd
QT comes with a widget designer and even in recent versions with an IDE to help design Qt software.
PySide
PySide is a LGPL binding to Qt. It's developed by nokia as a replacement for the GPL PyQt.
Although based on a different
technology than the existing
GPL-licensed PyQt bindings, PySide
will initially aim to be
API-compatible with them. In addition
to the PyQt-compatible API, a more
Pythonic API will be provided in the
future.
wxPython
wxPython is a binding for Python using the wxWidgets-Framework. This framework is under the LGPL licence and is developed by the open source community.
What I'm really missing is a good tool to design the interface, they have about 3 but none of them is usable.
One thing I should mention is that I found a bug in the tab-view despite the fact that I didn't use anything advanced. (Only on Mac OS X) I think wxWidgets isn't as polished as Qt.
wxPython is really only about the GUI-classes, there isn't much else.
wxWidgets uses native GUI elements.
An advantage wxPython has over Tkinter is that wxPython has a much larger library of widgets from which to choose from.
Others
I haven't got any experience with other GUI frameworks, maybe someone else has.

I'm just weighing in to say that TKinter sucks. It sadly seems that it is packed with Python because of backwards compatibility.
The documentation is horrible. It looks horrible. I have run into some bizarre bugs that will actually crash Python.

Jython.
Jython is an implementation of the
high-level, dynamic, object-oriented
language Python written in 100% Pure
Java, and seamlessly integrated with
the Java platform. It thus allows you
to run Python on any Java platform.
You can use either Swing, Applet, or other GUI frameworks available to Java platform. See Java Tutorials for Graphical User Interfaces and 2D Graphics. There are plenty of books and documentation such as API reference.
Here's a Hello world Swing application from An Introduction to Jython.
from javax.swing import *
frame = JFrame("Hello Jython")
label = JLabel("Hello Jython!", JLabel.CENTER)
frame.add(label)
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)
frame.setSize(300, 300)
frame.show()
Here's a Jython applet by Todd Ditchendorf that demonstrates multi-threaded particle drawing (60 lines).
from __future__ import nested_scopes
import java.lang as lang
import java.util as util
import java.awt as awt
import javax.swing as swing
class Particle:
def __init__(self,initX,initY):
self.x = initX
self.y = initY
self.rng = util.Random()
def move(self):
self.x += self.rng.nextInt(10) - 5
self.y += self.rng.nextInt(20) - 10
def draw(self,g2):
g2.drawRect(self.x,self.y,10,10)
class ParticleCanvas(awt.Canvas):
def __init__(self,newSize):
awt.Canvas.__init__(self,size=(newSize,newSize))
def paint(self,g2):
for p in self.particles:
p.draw(g2)
class ParticleApplet(swing.JApplet):
def init(self):
self.canvas = ParticleCanvas(self.getWidth())
self.contentPane.add(self.canvas)
def start(self):
n = 10
particles = []
for i in range(n):
particles.append(Particle(150,150))
self.canvas.particles = particles
self.threads = []
for i in range(n):
self.threads.append(self.makeThread(particles[i]))
self.threads[i].start()
def makeThread(self,p):
class MyRunnable(lang.Runnable):
def run(this):
try:
while 1:
p.move()
self.canvas.repaint()
lang.Thread.sleep(100)
except lang.InterruptedException:
return
return lang.Thread(MyRunnable())
If you are just interested in drawing lines and circles you can probably cut it down to half.

I would definitely appreciate it if anyone knows of something better than what's commonly discussed; I see to have headaches finding something appropriate...
Qt is great, but PyQt doesn't seem to have the same development resources. It seems to have some clever way to generate bindings, but isn't complete (e.g. PyKDE terminal kpart) and there is a dearth of documentation (as the developers admit). Compatibility with Qt's UI designer is nice.
wxpython - controls aren't as nice looking, widget library isn't as large as KDE.
OpenGL - doesn't even support fonts by default... pygame is okay, but opengl being a state machine is too annoying (object oriented models prevent making the a call in the wrong state).
XUL - neat idea, I wish it worked. The pyxulrunner tutorial didn't work for me, though -- first I had to add the xulrunner /usr/lib path to LD_LIBRARY_PATH, then it still had problems with "from xpcom import components"...
my wishlist for a ui library would be
Python integration (i.e. uses builtins like unicode, modules like threading, and language features like closures)
good intermediate representation (like XUL instead of generating hundreds of lines looking like "listbox91.addChild(label28)")
simple mutlithreaded support (automatic locks or event posting so e.g. elt.setText can be called from any thread; let the designer manage locking with Python locks if necessary)
user-centric features as well - scripting of a sequence of UI events, ability to keybind anything (KDE has dcop, but afaik binding isn't done automatically by the UI library), and intercept events.
potential for a large, easy-to-contribute standard library.
documentation, though if the library was well designed and generated enough interest, this would be a given.
In my experience, html is so much easier to get something good-looking up than UI libraries.
edit - after working with PyQt 4 for a while, it gets the job done for simple UI's. I'm currently not developing for end users, so looks don't matter. The QTextBrowser is very useful for displaying basic HTML tables and generating HTML links.

Pro wxPython
Lots of tutorials
wxGlade as an Editor: not perfect yet, but usable.