I'm trying to show a QFileDialog using the following piece of code:
import os, sys
from PyQt4.QtGui import *
class MainWindow(QWidget):
def __init__(self):
QWidget.__init__(self)
self._button = QPushButton('Test button')
self._button.clicked.connect(self._onButtonClicked)
self._layout = QHBoxLayout()
self._layout.addWidget(self._button)
self.setLayout(self._layout)
def _onButtonClicked(self):
self._dialog = QFileDialog(self, 'Select directory')
self._dialog.setDirectory(os.getenv('HOME'))
self._dialog.setFileMode(QFileDialog.Directory)
self._dialog.directoryEntered.connect(self._onDirEntered)
self._dialog.exec_()
def _onDirEntered(self, directory):
print("Entered directory: %s" % (directory))
if __name__ == "__main__":
app = QApplication(sys.argv)
mw = MainWindow()
mw.show()
app.exec_()
Two problems here:
The directoryEntered signal is never emitted, at least I don't get any output from the script (except for some KDE warnings about Samba support, etc.); actually no signal from the QFileDialog class I tried to connect to gets emitted in the example. What am I doing wrong?
In this example I set the starting directory to $HOME, but the dialog will start in /home instead and have my home directory selected in the listing instead of starting directly in my home directory. Can I change this behaviour somehow?
I'm using Python 3.4.0 with PyQt 4.10.4-2.
Both problems do not occur when using a non-native dialog as suggested by #ekhumoro.
Related
I am new to python and multiprocessing (Electronics background). I am writing an GUI application to communicate with micro controller over serial port. The interaction with user is through some buttons on the GUI, which sends some command on serial port to the MCU and displays data received from MCU in the same GUI(there can be data from MCU without any command being sent). I am using PyQt5 module and QT designer to design the UI. I converted the UI to py code using uic.compileUi. I am then calling this python file in my main code.
After reading through several documents and stack overflow posts I decided to use to QThreads for the application.
I am however facing issue with serial communication when being used inside thread (It works fine if used in a single main loop without threads).
My code is:
from PyQt5 import uic
from PyQt5.QtWidgets import QApplication,QWidget,QMainWindow #
from PyQt5.QtCore import QCoreApplication, QObject, pyqtSignal, pyqtSlot, QThread
import serial
from GUI import Ui_MainGUIWindow
import sys
serialString = ""
def ClosePort():
serialPort.close()
# print("port closed")
def OpenPort():
serialPort.open()
#print("port open")
def sendFV():
serialPort.write('fv\r'.encode())
def configSerial(port,baudRate):
global serialPort
serialPort=serial.Serial(port = port, baudrate=baudRate, bytesize=8, timeout=None, stopbits=serial.STOPBITS_ONE)
if not serialPort.isOpen():
serialPort.open()
class Worker(QObject):
finished = pyqtSignal()
dataReady = pyqtSignal(['QString'])#[int], ['Qstring']
print("workerinit")
def run(self):
print ("worker run")
while(1):
if(serialPort.in_waiting > 0):
serialString = serialPort.read()
self.dataReady.emit(str(serialString))
self.finished.emit()
class GUI(QWidget):
def __init__(self):
self.obj = Worker()
self.thread = QThread()
self.obj.dataReady.connect(self.onDataReady)
self.obj.moveToThread(self.thread)
self.obj.finished.connect(self.thread.quit)
self.thread.started.connect(self.obj.run)
self.thread.finished.connect(app.exit)
self.thread.start()
self.initUI()
def initUI(self):
#Form, Window = uic.loadUiType("TestGUI.ui")
#print(Form,Window)
#self.window = Window()
#self.form=Form()
self.window = QMainWindow()
self.form = Ui_MainGUIWindow()
self.form.setupUi(self.window)
self.form.FVButton.clicked.connect(sendFV)
print("guiinit")
self.window.show()
def onDataReady(self, serialString):
print("here")
print(serialString.decode('Ascii'))
self.form.plainTextOutput.insertPlainText((serialString.decode('Ascii')))
self.form.plainTextOutput.ensureCursorVisible()
if __name__ == '__main__':
configSerial("COM20",9600)
"""
app = QCoreApplication.instance()
if app is None:
app = QCoreApplication(sys.argv)
"""
app = QApplication(sys.argv)
form=GUI()
app.exec_()
sys.exit(ClosePort())
I get following error on line if(serialPort.in_waiting > 0):
File "C:\Users\...\Anaconda3\lib\site-packages\serial\serialwin32.py", line 259, in in_waiting
raise SerialException("ClearCommError failed ({!r})".format(ctypes.WinError()))
SerialException: ClearCommError failed (OSError(9, 'The handle is invalid.', None, 6))
I found this post talking about similar issue, but do know how exactly to implement the suggested solution in my code.
Also I get "kernel died" error multiple times when I run the code on spyder IDE. I added a check if I am creating multiple instances of QT application but that did not help.Running the code from anaconda command prompt works fine.
Using wxPython version 4.0.1 (pheonix) with python 3.6.5
I use a wxPython DirDialog to allow my user to input a start directory. It correctly selects and populates my "working directory" variable (using GetPath()) but then doesn't ever close the directory dialog prompt box.
I read through the wxPython-user google pages and the only related question I found referred to this as being "intended behavior," implying it would happen later in execution (https://groups.google.com/forum/#!searchin/wxpython-users/close%7Csort:date/wxpython-users/ysEZK5PVBN4/ieLGEWc6AQAJ).
Mine, however, doesn't close until the entire script has completed running (which takes a fair amount of time), giving me the spinning wheel of death. I have tried a combination of calls to try to force the window to close.
app = wx.App()
openFileDialog = wx.DirDialog(None, "Select", curr, wx.DD_DIR_MUST_EXIST)
openFileDialog.ShowModal()
working_directory = openFileDialog.GetPath()
openFileDialog.EndModal(wx.CANCEL) #also wx.Close(True) and wx.Destroy()
openFileDialog.Destroy()
openFileDialog=None
I have also tried creating a window, passing it as the parent of the DirDialog, and then closing the window and it gives the same behavior.
You don't mention which operating system you are on or version of wx but in the partial code that you supplied there is no MainLoop, which is what was mentioned by Robin Dunn in his answer, in your link.
Try this and see if it works the way you would expect.
import wx
from os.path import expanduser
import time
class choose(wx.Frame):
def __init__(self, parent):
wx.Frame.__init__(self, parent, -1, "Dialog")
panel = wx.Panel(self,-1)
text = wx.StaticText(panel,-1, "Place holder for chosen directory")
self.Bind(wx.EVT_CLOSE, self.OnClose)
self.Show()
curr = expanduser("~")
dlg = wx.DirDialog(None, message="Choose a directory", defaultPath = curr,
style=wx.DD_DEFAULT_STYLE|wx.DD_DIR_MUST_EXIST)
if dlg.ShowModal() == wx.ID_OK:
text.SetLabel(dlg.GetPath())
dlg.Destroy()
b = wx.BusyInfo("I'm busy counting",parent=None)
wx.Yield()
for i in range(30):
time.sleep(1)
del b
def OnClose(self, event):
self.Destroy()
if __name__ == '__main__':
my_app = wx.App()
choose(None)
my_app.MainLoop()
Intro
I encountered a problem while trying to learn PyQt5.
So far in my search for an answer and understanding to the problem i have come up mostly empty handed. A lot of links and posts i find does not apply to python or even Qt5 at all, which is not strange because SIGABRT applies to several fronts of memory allocation etc. (Correct me if I'm wrong).
I'm fairly certain that the error stems from the lines such as and similar to
buttonEnv.clicked.connect(lambda: self.btnClicked(buttonEnv))
But have not been able to locate or figure out what it is. Probably because of my lack of knowledge coming to python.
System
-OS: Arch linux (Manjaro) 4.9.27-1-MANJARO
-IDE: Pycharm 2017.1
-Python version: 3.6
-Using: PyQt5
Error I'm getting
/usr/bin/python3.6 /opt/pycharm-community/helpers/pydev/pydevd.py
--multiproc --qt-support --client 127.0.0.1 --port 42749 --file /home/alpeace/Documents/git_reps/project-tardis/main.py pydev debugger:
process 22588 is connecting
Connected to pydev debugger (build 171.4249.47)
Process finished with exit code 134 (interrupted by signal 6: SIGABRT)
My code
#!/usr/bin/python3
# -*- coding: utf-8 -*-
import sys
from PyQt5.QtWidgets import QMainWindow, QAction, qApp, QApplication, QGridLayout,\
QBoxLayout, QPushButton, QWidget, QSizePolicy
from PyQt5.QtGui import QIcon
class HomeScreen(QWidget):
clickedBtn = ''
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
self.clickedBtn = ''
homeBtnLayout = QGridLayout()
self.setLayout(homeBtnLayout)
buttonEnv = QPushButton('Environment')
buttonEnv.clicked.connect(lambda: self.btnClicked(buttonEnv))
buttonEnv.setSizePolicy(QSizePolicy.MinimumExpanding, QSizePolicy.Preferred)
buttonMedia = QPushButton('Media')
buttonMedia.clicked.connect(lambda: self.btnClicked(buttonMedia))
buttonMedia.setSizePolicy(QSizePolicy.MinimumExpanding, QSizePolicy.Preferred)
buttonInv = QPushButton('Inventory')
buttonInv.clicked.connect(lambda: self.btnClicked(buttonInv))
buttonInv.setSizePolicy(QSizePolicy.MinimumExpanding, QSizePolicy.Preferred)
buttonSched = QPushButton('Schedual')
buttonSched.clicked.connect(lambda: self.btnClicked(buttonSched))
buttonSched.setSizePolicy(QSizePolicy.MinimumExpanding, QSizePolicy.Preferred)
homeBtnLayout.addWidget(buttonEnv, 0, 0)
homeBtnLayout.addWidget(buttonMedia, 0, 1)
homeBtnLayout.addWidget(buttonInv, 1, 0)
homeBtnLayout.addWidget(buttonSched, 1, 1)
self.move(300, 150)
self.show()
def btnClicked(self, btnName):
self.clickedBtn = btnName.text()
btnName.disconnect()
def getClickedBtn(self):
return self.clickedBtn
class MainWindow(QMainWindow):
screenHome = HomeScreen()
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
self.setGeometry(300, 300, 300, 250)
self.setWindowTitle('Home')
self.screenHome = HomeScreen()
self.setCentralWidget(self.screenHome)
self.show()
def changeWindow(self):
newWindow = self.screenHome.getClickedBtn()
if newWindow == 'Environment':
print(newWindow)
elif newWindow == 'Media':
print(newWindow)
elif newWindow == 'Inventory':
print(newWindow)
elif newWindow == 'Schedual':
print(newWindow)
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = MainWindow()
sys.exit(app.exec_())
Anyways, thanks for reading and i hope someone might be able to help me with this. If more information is needed i will gladly provide it, but as far as I know this should be sufficient.
The problem is you're doing this on class level:
class MainWindow(QMainWindow):
screenHome = HomeScreen()
This means you're trying to create a HomeScreen at the very beginning, even before your main-block is running.
Since you're assigning self.screenHome properly later anyways:
def initUI(self):
# [...]
self.screenHome = HomeScreen()
you can simply get rid of the class level one.
By the way, the faulthandler module is useful in tracking things like this down - when putting an import faulthandler; faulthandler.enable() at the top, Python tells you on what line something happened - in this case it pointed to HomeScreen.__init__ so I've only had to figure out where a HomeScreen object is created before QApplication.
I am working on a very simple interface to explore/graph csv files. My aim is ultimately to explore, not to build software as I am not a developer, more of a "desperate user" :-)
I am leveraging the code found in this example
These are my first steps both in Python and in GUI, so I tend to put print messages in my calls so that I can more or less track what is happening. And this is where I found a strange behavior if I run the code from within Spyder.
import sys
import os
from PyQt4 import QtGui
import pandas as pd
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar
import matplotlib.pyplot as plt
# QtGui.QDialog
class Window(QtGui.QDialog):
def __init__(self, parent=None):
super(Window, self).__init__(parent)
# a figure instance to plot on
self.figure = plt.figure()
# this is the Canvas Widget that displays the `figure`
# it takes the `figure` instance as a parameter to __init__
self.canvas = FigureCanvas(self.figure)
# this is the Navigation widget
# it takes the Canvas widget and a parent
self.toolbar = NavigationToolbar(self.canvas, self)
# Just some extra button to mess around
self.button= QtGui.QPushButton('Push Me')
self.button.clicked.connect(self.do_print)
# set the layout
layout = QtGui.QVBoxLayout()
layout.addWidget(self.toolbar)
layout.addWidget(self.canvas)
layout.addWidget(self.button)
self.setLayout(layout)
def do_print(self):
print('Hello World!!')
if __name__ == '__main__':
app = QtGui.QApplication(sys.argv)
main = Window()
main.show()
sys.exit(app.exec_())
The strange behavior is that if I push the button once, nothing happens on the Ipython console. By the second time I push, then two "Hello World!" printouts appear.
If, on the other hand, I just launch my script from within a Windows Shell:
python my_simple_test.py
Then everything works as expected.
What am I then doing wrong from within Spyder?
Thanks,
Michele
IPython buffers stdout a bit differently from a terminal. When something is printed, it looks at how long it has been since it last flushed the buffer, and if it's longer than some threshold, it flushes it again. So the second time you click the button, it flushes stdout, and you see both outputs.
You can force it to flush immediately like this:
print('Hello World!!')
sys.stdout.flush()
I am working on adding a printer interface to some home-brewed Python3 code with a Gtk3 UI, using (mostly) Eclipse Indigo with the PyDev plugin.
While developing the PrintOperation callbacks I found a problem where apparently the gi-introspection fails to find the right underlying library struct for the Cairo Context. The error reported in the console is:
Traceback (most recent call last):
File "/home/bob/Projects/MovieList/src/MovieList/MovieListIO.py", line 203, in on_printDialog_draw_page
cr = context.get_cairo_context()
File "/usr/lib/python3/dist-packages/gi/types.py", line 43, in function
return info.invoke(*args, **kwargs)
TypeError: Couldn't find conversion for foreign struct 'cairo.Context'
At first I thought this was something to do with Eclipse and/or PyDev, because I could run the program within Idle without any error messages. But then I found that when the program was packaged for deployment with the built-in command-line Python tools, the installed version also gave the error. So, I wrote a couple of test scripts abstracting the printer functionality to try to isolate what was going on. In both cases, the key line is in the on_printOperation_draw_page() callback (marked with comments).
Here is the first test script (Script 1, printTestPdf.py), which loads a pdf file using Poppler, and prints it using the system print dialog:
#!/usr/bin/env python3
import os
from gi.repository import Gtk, Poppler
testFile = 'file://' + os.path.join(os.getcwd(), 'printTestPdf.pdf')
pdfDocument = Poppler.Document.new_from_file(testFile, None)
class Example(Gtk.Window):
def __init__(self):
super(Example, self).__init__()
self.init_ui()
def init_ui(self):
self.set_title("Print Pdf Test")
self.resize(230, 150)
self.set_position(Gtk.WindowPosition.CENTER)
self.connect("delete-event", Gtk.main_quit)
printButton = Gtk.Button('Press Me')
self.add(printButton)
printButton.connect('clicked', self.on_printButton_clicked)
self.show_all()
def on_printButton_clicked(self, widget):
"""
Handler for the button click.
"""
printOperation = Gtk.PrintOperation()
printOperation.connect('draw-page', self.on_printOperation_draw_page)
printOperation.set_job_name('Print Pdf Test')
printOperation.set_n_pages(pdfDocument.get_n_pages())
printOperation.run(Gtk.PrintOperationAction.PRINT_DIALOG,
parent=self)
def on_printOperation_draw_page(self, printOperation, context, pageNo):
"""
Handler for the draw-page signal from the printOperation.
"""
cr = context.get_cairo_context() # <-- THIS IS THE LINE
page = pdfDocument.get_page(pageNo)
page.render_for_printing(cr)
def main():
app = Example()
Gtk.main()
if __name__ == "__main__":
main()
This is the second script (Script 2, printTestHtml.py), which is almost identical, except it loads an HTML file for printing using weasyprint:
#!/usr/bin/env python3
import os
from gi.repository import Gtk
from weasyprint import HTML
testFile = os.path.join(os.getcwd(), 'printTestHtml.html')
pdfDocument = HTML(filename=testFile).render()
class Example(Gtk.Window):
def __init__(self):
super(Example, self).__init__()
self.init_ui()
def init_ui(self):
self.set_title("Print Html Test")
self.resize(230, 150)
self.set_position(Gtk.WindowPosition.CENTER)
self.connect("delete-event", Gtk.main_quit)
printButton = Gtk.Button('Press Me')
self.add(printButton)
printButton.connect('clicked', self.on_printButton_clicked)
self.show_all()
def on_printButton_clicked(self, widget):
"""
Handler for the button click.
"""
printOperation = Gtk.PrintOperation()
printOperation.connect('begin-print', self.on_printOperation_begin_print)
printOperation.connect('draw-page', self.on_printOperation_draw_page)
printOperation.set_job_name('Print HTML Test')
printOperation.set_n_pages(len(pdfDocument.pages))
printOperation.run(Gtk.PrintOperationAction.PRINT_DIALOG,
parent=self)
def on_printOperation_draw_page(self, printOperation, context, pageNo):
"""
Handler for the draw-page signal from the printOperation.
"""
cr = context.get_cairo_context() # <-- THIS IS THE LINE
page = pdfDocument.pages[pageNo]
page.paint(cr) # <-- there is a separate issue here
def main():
app = Example()
Gtk.main()
if __name__ == "__main__":
main()
Both scripts generate an internal pdf document, which is used to render each page on request via the PrintOperation draw_page callback.
Now, whether and how the scripts succeed or fail depends on the context in which they are run. Script 1 always works, except if it is run after a failure of Script 2 in Idle. Script 2 always generates the error message as reported above when run in Eclipse. In Idle, Script 2's behaviour is complex. Sometimes it fails due to a second problem (marked), and does not exhibit the first failure. However, for reasons I have yet to establish, every so often it generates the original error, and when it does, it keeps doing it and Script 1 show the error too, until Idle is re-booted. Running directly from the command line matches the behaviour in Eclipse. I have tried to summarise this behaviour below:
* Eclipse
- Script 1: Always OK
- Script 2: Always Fails
* Command line
- Script 1: Always OK
- Script 2: Always Fails
* Idle
- Script 1: OK, except after failure of Script 2
- Script 2: Intermittent Fail. Knock-on to future runs (up to next error)
This pattern of failure may help determine what the root problem is, but it is beyond me to understand it.
Ignoring the bizarre behaviour in Idle, it is possible the difference between Script 1 and Script 2 holds a clue to my original problem. Why does Script 1 run successfully, while Script 2 generates the introspection error?
If you can offer any suggestions as to what is going wrong I would be most grateful. If you can come up with a solution I will be delighted!
In view of the lack of response I have come up with the following workaround, which uses WebKit instead of weasyprint to do the parsing, rendering and administration of the printing from html:
#!/usr/bin/env python3
import os
from gi.repository import Gtk, WebKit
testFile = 'file://' + os.path.join(os.getcwd(), 'printTestHtml.html')
class Example(Gtk.Window):
def __init__(self):
super(Example, self).__init__()
self.init_ui()
def init_ui(self):
self.set_title("Print Html WebKit Test")
self.resize(230, 150)
self.set_position(Gtk.WindowPosition.CENTER)
self.connect("delete-event", Gtk.main_quit)
printButton = Gtk.Button('Press Me')
self.add(printButton)
printButton.connect('clicked', self.on_printButton_clicked)
self.show_all()
def on_printButton_clicked(self, widget):
webView = WebKit.WebView()
webView.load_uri(testFile)
webFrame = webView.get_main_frame()
webFrame.print_full(Gtk.PrintOperation(),
Gtk.PrintOperationAction.PRINT_DIALOG)
def main():
app = Example()
Gtk.main()
if __name__ == "__main__":
main()
What I think is going on is that somehow weasyprint interferes with the introspection process. I have raised this as a bug on the weasyprint home page on github.
Just in case it helps I was looking for a solution to the cairo error.
Had this cairo error happen on my RPi3 with Pandas and Matplotlib. The plot window was showing up blank.
I had to run sudo apt-get install python-gobject-cairo
Based on this: https://github.com/rbgirshick/py-faster-rcnn/issues/221