Frank,
Your example is a good demonstration of |QFileDialog|‘s signals.
However, since the processing runs in the GUI thread, the
progress bar is virtually useless as the GUI has no time to
update it. It starts empty, the application hangs, and then it is
filled when the processing is done.
Janwillem,
As I see it, if you would like a progress bar, you have three
options:
1. Call |QCoreApplication.processEvents()|
<http://seanfisk.github.io/pyside-docs/pyside/PySide/QtCore/QCoreApplication.html#PySide.QtCore.PySide.QtCore.QCoreApplication.processEvents>
during your processing code. This is not always a great idea,
and more of a hack than a solution. But it usually works.
2. Split your processing into chunks as in this example
<http://qt-project.org/wiki/Threads_Events_QObjects#72c9aabadf52900fbf3d4c1ff2b6008c>.
However, the code is a bit convoluted and it still runs in
the GUI thread. The whole page that contains that example is
a great read for asynchronous programming.
3. Send your processing to a thread, and dispatch events from
the thread indicating the progress.
The first two solutions involve running processing code within
the GUI thread. If any step of the processing takes longer than a
second, then it’s probably not a good idea as the user will see
the application hang. Here is an example implementation of the
third solution:
|#!/usr/bin/env python
# Example: Asynchronously process a directory of files with a progress bar.
import sys
import os
import time
from PySideimport QtCore, QtGui
class ProcessingThread(QtCore.QThread):
# Fired when each file is processed.
file_processed = QtCore.Signal(int, str)
def __init__(self, parent=None):
super(ProcessingThread, self).__init__(parent)
self.files = []
def run(self):
# Code that's run in the thread.
for i, filenamein enumerate(self.files):
# The actual code for one file goes here. Stubbed out with
# time.sleep() for now.
time.sleep(0.5)
print 'Processed:', filename
# Send update to the GUI thread.
self.file_processed.emit(i +1, filename)
class MyWidget(QtGui.QWidget):
def __init__(self, parent=None):
super(MyWidget, self).__init__(parent)
# Setup UI.
self._layout = QtGui.QVBoxLayout(self)
self._button = QtGui.QPushButton('Open files...')
self._progress = QtGui.QProgressBar()
self._filelist = QtGui.QPlainTextEdit()
self._layout.addWidget(self._button)
self._layout.addWidget(self._filelist)
self._layout.addWidget(self._progress)
# Setup events.
self._button.clicked.connect(self._button_clicked)
# Create the thread. Note that this doesn't actually _start_ it.
self._thread = ProcessingThread()
self._thread.file_processed.connect(self._file_processed)
# We need to wait for the thread before exiting. Either use this or
# don't let the user close the window if processing is happening.
See
# the next method in this class.
QtCore.QCoreApplication.instance().aboutToQuit.connect(
self._thread.wait)
# def closeEvent(self, event):
# # This is an alternative to waiting for the threads. Just don't
let
# # the user close the window.
# if self._thread.isRunning():
# QtGui.QMessageBox.critical(
# self, 'Processing',
# 'Cannot exit while processing is happening.')
# event.ignore()
# else:
# event.accept()
def _button_clicked(self):
# If we are already running the processing, produce an error.
if self._thread.isRunning():
QtGui.QMessageBox.critical(
self,'Processing',
'Can only process one directory at a time.')
return
# Get the directory name from the user.
dir_name = QtGui.QFileDialog.getExistingDirectory(
parent=self,
caption='Choose files...',
dir=os.getcwd())
# Activate the main dialog as it will be deactivated for some
reason
# after the file dialog closes (at least on my machine).
self.activateWindow()
# Get the list of files in the directory and prime the progress
bar.
files = os.listdir(dir_name)
# Set values for progress bar.
self._progress.setRange(0, len(files))
self._progress.setValue(0)
# Create and start the thread.
self._thread.files = files
self._thread.start()
def _file_processed(self, num_files_processed, filename):
# Called for each file that is processed.
self._filelist.appendPlainText(filename)
self._progress.setValue(num_files_processed)
if __name__ =='__main__':
app = QtGui.QApplication(sys.argv)
w = MyWidget()
w.show()
w.raise_()
raise SystemExit(app.exec_())|
This is all fine, but it might not solve your original problem of
the file dialog not closing. On my Mac, the file dialog is gone
as soon as the call to |getExistingDirectory()| finishes.
However, since I don’t have a runnable portion of your code, I
can’t really test it. I would recommend attempting to run my
example to see if it exhibits the same problem as your program.
Hope this helps!
Cheers,
--
Sean Fisk
On Tue, Dec 10, 2013 at 4:43 PM, Frank Rueter | OHUfx
<[email protected] <mailto:[email protected]>> wrote:
Here is an example using signals/slots
On 11/12/13 09:56, Janwillem van Dijk wrote:
Here is the snippet: It reads the filenames in a folder and
determines new names for photo's based on the exif info.
I apreciate that threading might be a solution but the
problem seems too simple for that. Can you give an example
on how to use the signal concept?
self.outFolder = QFileDialog.getExistingDirectory(
caption='Destination folder', dir=self.defOutFolder)
self.outFiles = []
if self.outFolder:
self.outFolder = self.outFolder.replace('\\', '/')
self.lineEdit_dest.setText(self.outFolder)
self.progressBar.setRange(0, self.numFiles)
for i, fname in enumerate(self.inFiles):
self.progressBar.setValue(i + 1)
newpath, newfname = rename_photo(self.inFolder, fname)
newpath = path.join(self.outFolder, newpath)
self.outFiles.append([fname, newpath, newfname])
s = fname + ' --> ' + self.outFolder + '\n'
s += path.join(newpath, newfname).replace(self.outFolder, '')
self.plainTextEdit_dest.appendPlainText(s)
On 10/12/13 21:35, Sean Fisk wrote:
Hi Janwillem,
Are you running the “lengthy part that processes a files
list” within the GUI thread? If so, you will probably see
your GUI hang while this is happening (you won’t be able to
click or do anything). In this case, you should consider
running the processing in a different thread using QThread
<http://seanfisk.github.io/pyside-docs/pyside/PySide/QtCore/QThread.html>
or QThreadPool
<http://seanfisk.github.io/pyside-docs/pyside/PySide/QtCore/QThreadPool.html>.
Can you post the relevant part of the code?
Thanks,
--
Sean Fisk
On Tue, Dec 10, 2013 at 3:17 PM, Janwillem van Dijk
<[email protected] <mailto:[email protected]>> wrote:
Hi, I have a PySide script that uses
QFileDialog.getExistingDirectory(). After clicking the
Open button the script proceeds with a lengthy part
that processes a files list and writes to a
QPlainTextEdit. Unfortunately the QFileDialog widget
does only disappear after this processing is finished,
hiding the QPlainTextEdit.
How can I make that the QFileDialog widget is gone
before the processing starts?
Cheers, Janwillem
_______________________________________________
PySide mailing list
[email protected] <mailto:[email protected]>
http://lists.qt-project.org/mailman/listinfo/pyside
