[Moved] How to use QProcess in a loop?

ManasQt

Hi All,
How to use QProcess in a loop and update QProgressBar in Main thread?

thanks,

andre

Don't. Just use the asynchronic API of QProcess (using signals & slots) and you do not need a loop.

ManasQt

Hi Andre,

     I have designed a Custom QDialog which has QProgessBar in StatusBar.

I am processing some process which performs some file conversions. Here i have 100s of files to convert and while conversion i have to update the progressbar simultaneously.
please give some sample code which deals with this kind of case.

tobias.hunger

That sounds like a good job for "Qt Concurrent":http://doc.qt.nokia.com/4.7-snapshot/threads-qtconcurrent.html:-) Check the documentation and examples that come with it.

ManasQt

Hi Tobias Hunger,
well i am using PySide so the one you are suggesting is not available.It would be great if you give me an alternative way to achieve this.

In My case,

i have a custom QDialog with 3 QPushButtons-Convert,Cancel,Finished and QProgressBar,QThread,QProcess

I am running QProcess inside QThread. and created a signal which sends the progressbar value to Main Thread.
here i am getting an Error: Cannot create children for a parent that is in a different thread

the 'Convert Button' does the bulk file conversions. So when user clicks on it,
i am running QThread.

please help me.

andre

Did you read the "wiki article":http://developer.qt.nokia.com/wiki/Threads_Events_QObjects on threading?

ManasQt

Hi All,
Please tell me why i am not able to update progressbar without freezing UI
@import sys,os

    self.thread=Thread()
    self.thread.setFiles(self.fileNames,self.exe_path)
    self.connect(self.thread,QtCore.SIGNAL("setProgressValue(int)"),self.updateProgressBar)
    self.connect(self.thread,QtCore.SIGNAL("updateLogInfo(QString)"),self.updateLogInfo)
    self.connect(self.thread, QtCore.SIGNAL("finished()"), self.threadFinished)
    self.connect(self.thread, QtCore.SIGNAL("terminated()"), self.threadTerminated)
    self.thread.start()

class Thread(QtCore.QThread):
setProgressValue=QtCore.Signal(int)
updateLogInfo=QtCore.Signal(str)
def init(self,parent=None):
QtCore.QThread.init(self,parent)
self.moveToThread(self)
def setFiles(self,files,exe_path):
print "setFiles"
self.files=files
self.exe_path=exe_path

def startProcessing(self):
    self.count=0
    self.process=QtCore.QProcess()
    self.process.setReadChannel(QtCore.QProcess.StandardOutput)
    self.process.setProcessChannelMode(QtCore.QProcess.MergedChannels)
    self.connect(self.process,QtCore.SIGNAL("readyReadStandardOutput()"),
    self,QtCore.SLOT("readyReadOutput()"))
    #self.connect(self.process,QtCore.SIGNAL("readyRead()"),
    self,QtCore.SLOT("readyRead()"))
    self.connect(self.process,QtCore.SIGNAL("readyReadStandardError()"),
    self,QtCore.SLOT("readyReadErrorOutput()"))
    self.connect(self.process,QtCore.SIGNAL("finished(int)"),self,QtCore.SLOT("processFinished(int)"))
    self.process.error.connect( self.processError )
    
    for filename in self.files:
        arguments=[]
        arguments.append(filename)
        self.process.start(self.exe_path,arguments)
            
        if self.process.waitForStarted():
            self.process.waitForBytesWritten()
            if not self.process.waitForFinished():
                print "exe failed:",self.process.errorString()
def run(self):
    QtCore.QTimer.singleShot(0,self,QtCore.SLOT("startProcessing()"))
    self.exec_()

def readyRead(self):
    if not self.process:
        return 
    print "readyRead"
    result=self.process.readAllStandardOutput()
    self.updateLogData(str(result.data()))
    
def readyReadOutput(self):
    if not self.process:
        return 
    print "readyReadOutput"
    result=self.process.readAllStandardOutput()
    self.updateLogData(str(result.data()))
    
def readyReadErrorOutput(self):
    if not self.process:
        return 
    print "readyReadErrorOutput"
    error=self.process.readAllStandardError()
    self.updateLogData(str(error.data()))
            
def processFinished(self,exitCode):
    if self.process.exitStatus()==QtCore.QProcess.ExitStatus.CrashExit:
        self.updateLogData(self.process.errorString())
    print "processFinished"
    self.updateProgressBarValue(self.count)
    
def processError(self):
    if not self.process:
        return 
    print "processError"
    self.updateLogData(self.process.errorString())
    
def updateProgressBarValue(self,value):
    self.emit(QtCore.SIGNAL("setProgressValue(int)"),value)
    
def updateLogData(self,data):
    self.emit(QtCore.SIGNAL("updateLogInfo(QString)"),data)

@

goetz

Moved to the language bindings forum.

ManasQt

Where is "Moved to the language bindings forum." link please!

goetz

I moved this thread to the mentioned forum. You find the link at the top of the page in the bread crumbs just above the thread title.

[Moved] How to use QProcess in a loop&#63;

[Moved] How to use QProcess in a loop?