maemo.org - Talk - Need help getting started with 'Qt' + C++ for N900 ..

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Need help getting started with 'Qt' + C++ for N900 ..

Hey all ... Well I've finally found some time to start trying to develop stuff for the N900, but there are some things which are confusing me which I need some assistance on ...

Firstly, I see there are two ways I can program for the N900: C++ and Python ... I've heard devloping using Python is somewhat easier, but since I dont know python and have been using c++ for 6-7 years now, I think C++ is the better option here ... Do you agree ?

Secondly, I'm trying to develop using Nokia's Qt technology, but there's a lot of jargon here on the forums which is confusing me. Can someone please clarify the difference between the following terms:

Qt 4.6 (or Qt 4.7) which is installed on the N900 ... Why is this need to be installed ? Are these the Header file libraries that would be used ?

Qt Creator and Qt Designer ... Isn't the latter part of the former ?

Nokia Qt SDK Framework .. How is this differenct from QT Creator ?

MADDE ... How is this related to the entire 'Qt' technology ?

PyQt ... I understand is for using Qt with Python, but this is an actual tool, or is it a name given to a group of programs (Qt Designer, Python, etc..), and is it an official Nokia bundle/program ?

As you can see, I'm just trying to piece together the terms right now, so I know what is being discussed when I search the forums ..

Lastly, if anyone knows any tutorial here on how to start developing Apps for N900 in C++ using Qt, please do post the link .. !

Thanks !

Re: Need help getting started with 'Qt' + C++ for N900 ..

Hi!

If you have a strong background on C++, I suggest you go that way for Qt, since Qt is written in C++ and you are probably going to feel more confortably with it.

Qt are the UI libraries (well, actually it does more things but for now take it like it only does UI) created by trolltech (now part of Nokia). In Linux, the UI part is much more layered than in other operating systems. You have the part which is the X windows, which gives you the basic operations for performing drawings on the screen. In top of that, there are some toolkits like Gtk which is the one Maemo is actually using. Because of Gtk being the toolkit used by Maemo, you need Qt installed on the N900 (on the last firmware PR1.2, Qt 4.6 is already integrated on it)

AFAIK, Qt designer is the UI designer being used on Qt Creator. Qt creator is a complete IDE which uses Qt designer for desinging the UIs.

Nokia Qt SDK comes with Qt Creator, Qt itself, a N900/Maemo emulator and a Symbian emulator, and tools for crosscompiling to those.

MADDE is an alternative SDK for Maemo. It helps you crosscompiling your source code

PyQt is actually the bindings for using Qt on Python. There are also another bindings made by Nokia which are API compatible with PyQt called Pyside.

I hope it helps you.

Re: Need help getting started with 'Qt' + C++ for N900 ..

Quote:

Originally Posted by ahmadka (Post 700949)

What you heard is correct. I suggest you go with python first. I find python+qt to be easier than it should :-)

Open an ssh connection to your N900 and write this to a file:

Code:

#!/usr/bin/python



# Convenience imports

from PyQt4.QtCore import *

from PyQt4.QtGui import *



import sys



# This is a decorator class

class WinUi:

  # With only one function to decorate a window

  def setupUi(self, parent):

    self.centralwidget=QWidget(parent)

    parent.setCentralWidget(self.centralwidget)



    # A horizontal layout

    self.layout=QHBoxLayout(self.centralwidget)

   

    # With three items

    self.label=QLabel("Name:", self.centralwidget)

    self.txt=QLineEdit(self.centralwidget)

    self.but=QPushButton(self.centralwidget)



    l=self.layout



    # Add them to the layout

    l.addWidget(self.label)

    l.addWidget(self.txt)

    l.addWidget(self.but)

        

    # Se the label of the button

    self.but.setText("OK")



class Win(QMainWindow):

  def __init__(self):

    QMainWindow.__init__(self)



    # Setup the UI using the decorator class

    self.ui=WinUi()

    self.ui.setupUi(self)



    # Connect the mouse "clicked" event to a function

    self.ui.but.clicked.connect(self.click)



  def click(self):

    txt=self.ui.txt.text()

    if txt=='':

      QMessageBox.critical(self, "Error", "Please type something")

    else:

      QMessageBox.information(self, "Success", "You typed: %s" % txt)



# Standard things

# Create an application then create a window.

# Show the window and run the main loop

app=QApplication(sys.argv)

win=Win()

win.show()

app.exec_()

Take care of the spaces. They matter in python. Then run:

Code:

python myfile.py

where myfile.py is the filename you used.

The WinUi class will come from qt-designer so your program will be just the Win class and some standard stuff.

Being able to develop directly on N900 is an extra bonus of using python.

Re: Need help getting started with 'Qt' + C++ for N900 ..

C++ and Python are two possible languages to use. You can develop for the N900 in C (for easy GTK+-2.0 integration), shellscript, LISP or LUA. Take your pick.

But, if you want to rely on the SDK, C++ and Qt is the dominant variant.