Develop Reference

Internationalization (translation) of dialog and the main window in a pyqt5 application

I am trying to translate my small application written in pyside2/pyqt5 to several languages, for example, Chinese. After googling, I managed to change the main window to Chinese after select from the menu -> language -> Chinese. However, the pop up dialog from menu -> option still remains English version. It seems the translation info is not transferred to the dialog. How do I solve this?
Basically, I build two ui files in designer and convert to two python files:One mainui.py and one dialogui.py. I then convert the two python file into one *.ts file using
pylupdate5 -verbose mainui.py dialogui.py -ts zh_CN.ts
after that, in linguist input the translation words. I can see the items in the dialog, which means this information is not missing. Then I release the file as zh_CN.qm file. All this supporting file I attached below using google drive.
Supporting files for the question
The main file is as
import os
import sys
from PySide2 import QtCore, QtGui, QtWidgets
from mainui import Ui_MainWindow
from dialogui import Ui_Dialog
class OptionsDialog(QtWidgets.QDialog,Ui_Dialog):
def __init__(self,parent):
super().__init__(parent)
self.setupUi(self)
self.retranslateUi(self)
class MainWindow(QtWidgets.QMainWindow,Ui_MainWindow):
def __init__(self):
super().__init__()
self.setupUi(self)
self.actionConfigure.triggered.connect(self.showdialog)
self.actionChinese.triggered.connect(self.change_lang)
def showdialog(self):
dlg = OptionsDialog(self)
dlg.exec_()
def change_lang(self):
trans = QtCore.QTranslator()
trans.load('zh_CN')
QtCore.QCoreApplication.instance().installTranslator(trans)
self.retranslateUi(self)
if __name__=='__main__':
app = QtWidgets.QApplication(sys.argv)
mainWin = MainWindow()
mainWin.show()
ret = app.exec_()
sys.exit(ret)
I think it should be a typical task because almost no application will only have a mainwindow.

You have to overwrite the changeEvent() method and call retranslateUi() when the event is of type QEvent::LanguageChange, on the other hand the QTranslator object must be a member of the class but it will be deleted and it will not exist when the changeEvent() method is called.
Finally assuming that the Language menu is used to establish only translations, a possible option is to establish the name of the .qm as data of the QActions and to use the triggered method of the QMenu as I show below:
from PySide2 import QtCore, QtGui, QtWidgets
from mainui import Ui_MainWindow
from dialogui import Ui_Dialog
class OptionsDialog(QtWidgets.QDialog,Ui_Dialog):
def __init__(self,parent):
super().__init__(parent)
self.setupUi(self)
def changeEvent(self, event):
if event.type() == QtCore.QEvent.LanguageChange:
self.retranslateUi(self)
super(OptionsDialog, self).changeEvent(event)
class MainWindow(QtWidgets.QMainWindow,Ui_MainWindow):
def __init__(self):
super().__init__()
self.setupUi(self)
self.m_translator = QtCore.QTranslator(self)
self.actionConfigure.triggered.connect(self.showdialog)
self.menuLanguage.triggered.connect(self.change_lang)
# set translation for each submenu
self.actionChinese.setData('zh_CN')
#QtCore.Slot()
def showdialog(self):
dlg = OptionsDialog(self)
dlg.exec_()
#QtCore.Slot(QtWidgets.QAction)
def change_lang(self, action):
QtCore.QCoreApplication.instance().removeTranslator(self.m_translator)
if self.m_translator.load(action.data()):
QtCore.QCoreApplication.instance().installTranslator(self.m_translator)
def changeEvent(self, event):
if event.type() == QtCore.QEvent.LanguageChange:
self.retranslateUi(self)
super(MainWindow, self).changeEvent(event)
if __name__=='__main__':
import sys
app = QtWidgets.QApplication(sys.argv)
mainWin = MainWindow()
mainWin.show()
ret = app.exec_()
sys.exit(ret)

Access QT Designer Objects Programmatically

Disclaimer: New to both python and qt designer
QT Designer 4.8.7
Python 3.4
PyCharm 5.0.3
Question - How do I add controls to the main form or a scroll area widget on the main form (created in QT Designer) programmatically?
I have created a MainWindow in qt designer and added my widgets. The following is the entire test program in PyCharm:
import sys
from PyQt4 import QtGui, QtCore, uic
from PyQt4.QtGui import *
from PyQt4.QtCore import *
qtCreatorFile = "programLauncher.ui"
Ui_MainWindow, QtBaseClass = uic.loadUiType(qtCreatorFile)
class MyApp(QtGui.QMainWindow, Ui_MainWindow):
def __init__(self):
QtGui.QMainWindow.__init__(self)
Ui_MainWindow.__init__(self)
self.setupUi(self)
# Cannot resize or maximize
self.setFixedSize(1045, 770)
# Add button test
self.dateLabel = QtGui.QLabel("Test")
self.pushButton = QtGui.QPushButton('Test button')
# self.scrollArea_programs.addWidget()
grid = QtGui.QGridLayout()
# self.scrollArea_programs.addWidget(self.pushButton)
grid.addWidget(self.dateLabel,0,0)
grid.addWidget(self.pushButton,0,1)
self.setLayout(grid)
self.pushButton_exit.clicked.connect(self.closeEvent)
def closeEvent(self):
QtGui.QApplication.quit()
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
window = MyApp()
window.show()
sys.exit(app.exec_())
As you can see I tried to add controls to a grid but nothing shows up when the program runs - I have also tried to add a control to the scroll area. Can someone help me to just add 1 control to the scroll area at run time - so then I can know the proper way to do it or "a" proper way to do this.
Thanks in advance

Without having access to your programLauncher.ui and making minimal changes to your posted code, you can add your UI elements to the window like so:
from PyQt4 import QtGui
import sys
class MyApp(QtGui.QMainWindow):
def __init__(self):
QtGui.QMainWindow.__init__(self)
# Cannot resize or maximize
self.setFixedSize(1045, 770)
widget = QtGui.QWidget(self)
self.setCentralWidget(widget)
# Add button test
self.dateLabel = QtGui.QLabel("Test")
self.pushButton = QtGui.QPushButton('Test button')
grid = QtGui.QGridLayout()
grid.addWidget(self.dateLabel, 0, 0)
grid.addWidget(self.pushButton, 0, 1)
widget.setLayout(grid)
self.pushButton.clicked.connect(self.closeEvent)
def closeEvent(self, event):
QtGui.QApplication.quit()
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
window = MyApp()
window.show()
sys.exit(app.exec_())
This will get the controls on the screen, although the layout leaves a lot to be desired. You may have to make modifications to this based on what's in your .ui file. One thing that you'll want to note in this example is that the QMainWindow needs a central widget (widget in the example above). You then set the layout on that widget.

You can use the designer to create your .ui file
The you can load it in your .py using something like:
from PyQt4 import QtCore, QtGui, uic
class my_win(QtGui.QMainWindow):
def __init__(self):
self.ui = uic.loadUi('my_ui.ui',self)
then you can access all your widgets with something like
self.ui.actionQuit.triggered.connect(QtGui.qApp.quit)
or
self.ui.my_button.triggered.connect(self.do_someting)

Thanks to JCVanHamme (the programLauncher.ui hint) and also outside help I now learned most of what I need to know to access MainWindow at run time. So for anyone interested in this beginner tip:
Take a blank form in QT Designer
Add a control
Run pyuic4 batch file
Take a look at the generated .py file to learn EVERYTHING about how to add controls.
Don't let the power go to your head - cheers

SVG icons with PyQt on Windows and Linux

I have a PyQt user interface as follows
import sys
from PyQt4 import QtGui
class Example(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Example, self).__init__(parent)
self.setWindowTitle('Example')
self.setWindowIcon(QtGui.QIcon('note_add.svg'))
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
ex.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
It works fine on Linux but it doesn't work well on Windows, because the SVG icon doesn't appear. I have two questions:
What is the proper way to use SVG icons with PyQt on Windows?
Is there a way to change the color fill of an SVG icon on the fly? This should work fine on both operating systems.

I know this is a few years late. But, better late than never. :)
For me, Qt works best when I define a specific directory. So, I'd implement this as so:
import sys
import os
from PyQt4 import QtGui
class Example(QtGui.QMainWindow):
def __init__(self, parent=None):
super(Example, self).__init__(parent)
### Newly added code ###
self.current_directory = os.path.dirname(__file__)
self.note_icon = os.path.join( self.current_directory, 'note_add.svg' )
### ### ### ###
self.setWindowTitle('Example')
self.setWindowIcon(QtGui.QIcon(self.note_icon))
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
ex.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()

A QApplication instance already exists

I'm doing some simple PySide on 3Dsmax 2015.
This is my error:
python.ExecuteFile "C:\Program Files\Autodesk\3ds Max 2015\scripts\Python\demoUniTest.py"
-- Runtime error: Line 32 <module>()
<type 'exceptions.RuntimeError'> A QApplication instance already exists.
This is my code:
import sys
from PySide.QtCore import *
from PySide.QtGui import *
from math import *
class Form(QDialog):
def __init__(self,parent=None):
super(Form,self).__init__(parent)
self.browser = QTextBrowser()
self.lineedit = QLineEdit("Type an expression and press Enter")
self.lineedit.selectAll()
layout = QVBoxLayout()
layout.addWidget(self.browser)
layout.addWidget(self.lineedit)
self.setLayout(layout)
self.lineedit.setFocus()
self.connect(self.lineedit, SIGNAL("returnPressed()"),self.updateUi)
self.setWindowTitle("Calculate")
def updateUi(self):
try:
text = self.lineedit.text()
self.browser.append("%s = <b>%s</b>" % (text,eval(text)))
except:
self.browser.append("<font color=red>%s is invalid</font>" %text)
app = QApplication(sys.argv)
form = Form()
form.show()
app.exec_()
When I use this code on Pycharm,I don't get any errors. It only appears when I use it on 3Dsmax 2015 Listener

Direct citation from the helpfile (Using PySide):
Normally one creates a PySide application object in a script using
QtGui.QApplication(). However, in 3ds Max, there is already a PySide
application running, so you get a handle for that object like this:
QtGui.QApplication.instance()

As a note this has changed somewhat in 3DS Max 2018 and PySide2. I'm just playing around with it myself right now and I was able to get it working after a bit of tinkering. Here's a link to the documentation, though be warned that there is a small typo in the code (at least at the time of writing): http://help.autodesk.com/view/3DSMAX/2018/ENU/?guid=__developer_what_s_new_in_3ds_max_python_api_what_s_new_in_the_3ds_max_2018_p_html
As mentioned in other answers you need to make your UI a child of the main 3DS Max application. The good news is that they have simplified this a bit for you with the function GetQMaxMainWindow(). Use it like this:
from PySide2 import QtWidgets, QtCore, QtGui
import MaxPlus
import os
class SampleUI(QtWidgets.QDialog):
def __init__(self, parent=MaxPlus.GetQMaxMainWindow()):
super(SampleUI, self).__init__(parent)
self.initUI()
def initUI(self):
mainLayout = QtWidgets.QHBoxLayout()
testBtn = QtWidgets.QPushButton("Test!")
mainLayout.addWidget(testBtn)
self.setLayout(mainLayout)
if __name__ == "__main__":
try:
ui.close()
except:
pass
ui = SampleUI()
ui.show()

You're creating an instance of QApplication in the line:
app = QApplication(sys.argv)
And getting that error because there's another instance of QApplication created somewhere before that (presumably somewhere in "3Dsmax 2015 Listener") and you're only allowed one.
See:
QT documentation on QApplication

Howto embed a video via mpylayer into a QWidget frame?

Is it possible in PyQt4 to embed a video via mpylayer into a QWidget (or into a subclass of it). If so, could you provide a minimal working example.

For a complete example of a Qt Widget that embeds MPlayer, try qmpwidget.
But here's a minimal PyQt demo to get you started:
import mpylayer
from PyQt4 import QtGui, QtCore
class Window(QtGui.QWidget):
def __init__(self):
QtGui.QWidget.__init__(self)
self.container = QtGui.QWidget(self)
self.container.setStyleSheet('background: black')
self.button = QtGui.QPushButton('Open', self)
self.button.clicked.connect(self.handleButton)
layout = QtGui.QVBoxLayout(self)
layout.addWidget(self.container)
layout.addWidget(self.button)
self.mplayer = mpylayer.MPlayerControl(
'mplayer', ['-wid', str(self.container.winId())])
def handleButton(self):
path = QtGui.QFileDialog.getOpenFileName()
if not path.isEmpty():
self.mplayer.loadfile(unicode(path))
if __name__ == '__main__':
import sys
app = QtGui.QApplication(sys.argv)
window = Window()
window.resize(640, 480)
window.show()
sys.exit(app.exec_())
(NB: this demo has only been tested on Linux)

You have to get the handle (id) of the widget → http://qt-project.org/doc/qt-4.8/qwidget.html#winId
And pass it to the -wid option of the MPlayer.
I can't provide you an example with Qt, simply because I don't know Qt, but I already wrote an MplayerCtrl for wxPython: https://bitbucket.org/dav1d/mplayerctrl
Relevant Code: https://bitbucket.org/dav1d/mplayerctrl/src/c680a1d99ad2/MplayerCtrl.py#cl-873