[PySide] wait for QFileDialog to close
Janwillem van Dijk
jwevandijk at xs4all.nl
Wed Dec 11 22:30:36 CET 2013
On 11/12/13 21:56, Sean Fisk wrote:
> Janwillem,
>
> I'm glad you were able to able to figure out the problem. Sorry for my
> red herrings!
>
> Frank,
>
> I thought about it, and I have no idea why the progress bar works fine
> for you and not for me. It hangs for me, which is exactly what I
> expected to happen. Maybe some platform difference? I'm on Mac OS 10.6
> with PySide 1.2.1.
>
>
> --
> Sean Fisk
>
>
> On Wed, Dec 11, 2013 at 9:16 AM, Janwillem van Dijk
> <jwevandijk at xs4all.nl <mailto:jwevandijk at xs4all.nl>> wrote:
>
> The solution Frank proposed yesterday works (after I found out
> that you can get the output using selectedFiles()[0]).
> No problems with the progressbar.
> The actual processing can take a bit long because the exif's of
> digital camera shots are analysed (GExiv2 for photos and exiftool
> for movies ) and than copied to folders as
> /camara_make/year/month/imagetype/yyyymmddhhmmss_fname. When
> copying more than say 50 16MB raw photos the gui becomes blocked.
> In other apps I indeed solved that with threading but, although
> not elegant, I decided to live with that for this one.
> Many thanks for teaching me this extra bit of Python.
> Cheers, Janwillem
>
>
> On 11/12/13 05:45, Sean Fisk wrote:
>>
>> 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
>> <frank at ohufx.com <mailto:frank at ohufx.com>> 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
>>>> <jwevandijk at xs4all.nl <mailto:jwevandijk at xs4all.nl>> 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
>>>> PySide at qt-project.org <mailto:PySide at qt-project.org>
>>>> http://lists.qt-project.org/mailman/listinfo/pyside
>>>>
>>>>
>>>
>>
>>
>
>
I am on Linux (Ubuntu 13.10) and Python 3.2 developing using Spyder
2.3.0beta (I am a numpy scipy matplotlib user). I am not aware that
gexiv2 is available for Windows so I cannot test that.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/pyside/attachments/20131211/4c1ea368/attachment.html>
More information about the PySide
mailing list