Languages/Python/PyKDE Knotify Tutorial: Difference between revisions

    From KDE TechBase
    (terimation)
    (Mark for archiving)
     
    (5 intermediate revisions by 4 users not shown)
    Line 1: Line 1:
    {{Template:I18n/Language Navigation Bar|Development/Languages/Python/PyKDE_Knotify_Tutorial}}
    {{Archived}}
    {{Warning|This tutorial uses Qt4, PyQt4, and PyKDE4.}}


    {{TutorialBrowser|
    {{TutorialBrowser|
    Line 24: Line 25:
    We start with a minimal KDE Appliciation ([http://techbase.kde.org/Development/Languages/Python/Using_PyKDE_4 Using PyKDE4]):
    We start with a minimal KDE Appliciation ([http://techbase.kde.org/Development/Languages/Python/Using_PyKDE_4 Using PyKDE4]):


    <code python>
    <syntaxhighlight lang="python">
    #! /usr/bin/python
    #! /usr/bin/python
    # -*- coding: utf-8 -*-
    # -*- coding: utf-8 -*-
    Line 52: Line 53:
          
          
         app = KApplication ()
         app = KApplication ()
    </code>
    </syntaxhighlight>


    == Job class ==
    == Job class ==
    Line 61: Line 62:
    So it is easy to write a small Job-Class:
    So it is easy to write a small Job-Class:


    <code python>
    <syntaxhighlight lang="python">
    from PyQt4.QtCore import QObject,QTimer,QString
    from PyQt4.QtCore import QObject,QTimer,QString
    from PyKDE4.kdecore import KJob
    from PyKDE4.kdecore import KJob
    Line 124: Line 125:
             #return True for signaling that we support killing
             #return True for signaling that we support killing
             return True
             return True
    </code>
    </syntaxhighlight>


    ===What is going on?===
    ===What is going on?===
    Line 134: Line 135:
    ===How to use?===
    ===How to use?===
    Just create a instance of this class and start it:
    Just create a instance of this class and start it:
    <code python>
    <syntaxhighlight lang="python">
    job=MyJob(app)
    job=MyJob(app)
    job.start()
    job.start()
    </code>
    </syntaxhighlight>


    ===We want to know when the jobs done?===
    ===We want to know when the jobs done?===
    Create a '''SLOT''' to the '''result'''-signal:
    Create a '''SLOT''' to the '''result'''-signal:
    <code python>
    <syntaxhighlight lang="python">
    def handleResult(job):
    def handleResult(job):
         #handleResult Function
         #handleResult Function
    Line 154: Line 155:


    job.result.connect(handleResult)
    job.result.connect(handleResult)
    </code>
    </syntaxhighlight>


    Now we also add '''app.exec_()''' at the end of the main part, to prevent the program to stop before the job is stopped.
    Now we also add '''app.exec_()''' at the end of the main part, to prevent the program to stop before the job is stopped.
    Line 161: Line 162:
    Till now, a normal user doesn't see anything what is going on. To change it we have to register the Job to a JobTracker.  Now a user will see a progressbar and a suspend and a stop button. So we modify the start method:
    Till now, a normal user doesn't see anything what is going on. To change it we have to register the Job to a JobTracker.  Now a user will see a progressbar and a suspend and a stop button. So we modify the start method:


    <code python>
    <syntaxhighlight lang="python">
    from PyKDE4.kio import KIO
    from PyKDE4.kio import KIO
    ...
    ...
    Line 169: Line 170:
             self.i=0
             self.i=0
             QTimer().singleShot(0, self.doWork)
             QTimer().singleShot(0, self.doWork)
    </code>
    </syntaxhighlight>
     
    === Setting the job title and description ===
    Now you have the running job and a user can see nice progressbar. However, there is no visible information what job is currently running and what it is doing. To change it we have to emit signal '''KJob.description''' in our method '''MyJob.doWork''':
     
     
    <syntaxhighlight lang="python">
        def doWork(self):           
            #the actual work                                       
            try:           
                #if we are killed or suspended just return                                         
                if self.error() or self.isSuspended():                   
                    return
            except RuntimeError:
                #if this class is killed before a RuntimeError will raise
                return
     
            #do a peace of hard work
            self.i+=1
     
            #fortunately we have made a peace of work
            #-> show this to everybody
            KJob.setPercent(self,self.i*4)
            self.description.emit(self, "Our Splendid Job", ("Source","counter"), ("Destination","dummy"))
         
            if self.i==self.max:
                #jeah we have done the bunch of work
                #send the result signal for showing, that we ended the work
                self.emitResult()
                return
            #just go to sleep for 1000ms than go on
            QTimer().singleShot(1000, self.doWork)
    </syntaxhighlight>
     
    The parameters of this signal are the sending job (anything else than '''self''' doesn't make sense here), job title, and two tuples consising of two strings arbitrary that can be used to denote some job details. (consider them as a key-value pair).


    === Conclusion ===
    === Conclusion ===
    Here is the [[Development/Languages/Python/PyKDE_Knotify_Tutorial/MyJob.py|full code]] of this example.  
    Here is the [[Development/Languages/Python/PyKDE_Knotify_Tutorial/MyJob.py|full code]] of this example.  


    Is is very easy to create a Job and make it visible to normal users. Unfortunately I have problems with setting the heading and description, so this will be added in later versions.
    Is is very easy to create a Job and make it visible to normal users.

    Latest revision as of 13:46, 31 May 2019


    This page has been archived
    The information on this page is outdated or no longer in use but is kept for historical purposes. Please see the Category:Archives for similar pages.
    Warning
    This tutorial uses Qt4, PyQt4, and PyKDE4.


    Python KNotify Tutorial
    Tutorial Series   Python
    Previous   None
    What's Next  
    Further Reading   Qt Signals and Slots in python, Introduction to PyQT4, Using PyKDE4

    Abstract

    The aim of this tutorial is to give a sample class to include Notifications and Jobs to your own python programms, so the user can see what is going on (for example a backup system, that tells you that is backuping right now). It assumes a basic working knowledge of Python and PyKDE4. For now only the Job part is mentioned, 'cause that is the only part I've created right now.

    Further plans

    To add the Notification part also to this tutorial.

    Instruction

    We start with a minimal KDE Appliciation (Using PyKDE4):

    #! /usr/bin/python
    # -*- coding: utf-8 -*-
    
    if __name__ == "__main__":
        import sys
        
        from PyKDE4.kdecore import KCmdLineArgs, KAboutData, KLocalizedString, ki18n
        from PyKDE4.kdeui import KApplication    
        
        appName     = "default"
        catalog     = ""
        programName = ki18n ("default")  
        version     = "1.0"
        description = ki18n ("Default Example")  
        license     = KAboutData.License_GPL
        copyright   = ki18n ("(c) 2010 Sandro Knauß") 
        text        = ki18n ("none") 
        homePage    = "techbase.kde.org"
        bugEmail    = "[email protected]"
    
        aboutData   = KAboutData (appName, catalog, programName, version, description,
                                  license, copyright, text, homePage, bugEmail)
    
        
        KCmdLineArgs.init (sys.argv, aboutData)
        
        app = KApplication ()
    

    Job class

    The first step is to have a look to the [1]. The intersting on is:

    So it is easy to write a small Job-Class:

    from PyQt4.QtCore import QObject,QTimer,QString
    from PyKDE4.kdecore import KJob
    
    class MyJob(KJob):
        def __init__(self,parent=QObject()):
            KJob.__init__(self,parent)
            #We want to have a Suspenable and Killable Job
            self.setCapabilities(KJob.Capabilities(KJob.Suspendable|KJob.Killable))
    
            #Just a maximum Variable
            self.max=25
    
            #index
            self.i=0
    
        def start(self):
            #initalizing for work
            self.i=0
           
            #start the actual work in another thread
            #this function has to terminate, before the work is done
            QTimer().singleShot(0, self.doWork)
                                                                                                                                                   
        def doWork(self):             
            #the actual work                                         
            try:            
                #if we are killed or suspended just return                                           
                if self.error() or self.isSuspended():                    
                    return
            except RuntimeError:
                #if this class is killed before a RuntimeError will raise
                return
    
            #do a peace of hard work
            self.i+=1
    
            #fortunately we have made a peace of work 
            #-> show this to everybody
            KJob.setPercent(self,self.i*4)
           
            if self.i==self.max:
                #jeah we have done the bunch of work
                #send the result signal for showing, that we ended the work
                self.emitResult()
                return 
            #just go to sleep for 1000ms than go on
            QTimer().singleShot(1000, self.doWork)
        
        def doSuspend(self):
            #the surounding function from KJob makes the isSuspended() become True
            #returns True for signaling that this class supports to suspend
            return True
    
        def doResume(self):
            #start with work again
            QTimer().singleShot( 0, self.doWork )
            #return True for signaling that this class supports resuming
            return True
    
        def doKill(self):
            #return True for signaling that we support killing
            return True
    

    What is going on?

    • MyJob.__init__: First we create the class and initialize the counter i and the maximum max. To make is visible for others we set the Capacities, so this job is suspendable and killable.
    • MyJob.start: Here the pre working setting are made, we will se later for what we use this. After initalizing the Work we start the actual work by using a QTimer. The start method should start the asyncron.
    • MyJob.doWork: Do actual work and handle, if this job is killed or suspended.
    • MyJob.doSuspend/MyJob.doResume/MyJob.doKill: These function indicate that this feature is supported by this class.

    How to use?

    Just create a instance of this class and start it:

    job=MyJob(app)
    job.start()
    

    We want to know when the jobs done?

    Create a SLOT to the result-signal:

    def handleResult(job):
        #handleResult Function
        #it is called when the job is terminating
        if job.error():
           print 'error happend'
        else:
           print 'job has terminated successfully'
        
        #for terimation the complete application
        sys.exit()
    
    job.result.connect(handleResult)
    

    Now we also add app.exec_() at the end of the main part, to prevent the program to stop before the job is stopped.

    Visual feedback

    Till now, a normal user doesn't see anything what is going on. To change it we have to register the Job to a JobTracker. Now a user will see a progressbar and a suspend and a stop button. So we modify the start method:

    from PyKDE4.kio import KIO
    ...
        def start(self):
            #register the Job to the JobTracker
            KIO.getJobTracker().registerJob(self)
            self.i=0
            QTimer().singleShot(0, self.doWork)
    

    Setting the job title and description

    Now you have the running job and a user can see nice progressbar. However, there is no visible information what job is currently running and what it is doing. To change it we have to emit signal KJob.description in our method MyJob.doWork:


        def doWork(self):             
            #the actual work                                         
            try:            
                #if we are killed or suspended just return                                           
                if self.error() or self.isSuspended():                    
                    return
            except RuntimeError:
                #if this class is killed before a RuntimeError will raise
                return
    
            #do a peace of hard work
            self.i+=1
    
            #fortunately we have made a peace of work 
            #-> show this to everybody
            KJob.setPercent(self,self.i*4)
            self.description.emit(self, "Our Splendid Job", ("Source","counter"), ("Destination","dummy"))
           
            if self.i==self.max:
                #jeah we have done the bunch of work
                #send the result signal for showing, that we ended the work
                self.emitResult()
                return 
            #just go to sleep for 1000ms than go on
            QTimer().singleShot(1000, self.doWork)
    

    The parameters of this signal are the sending job (anything else than self doesn't make sense here), job title, and two tuples consising of two strings arbitrary that can be used to denote some job details. (consider them as a key-value pair).

    Conclusion

    Here is the full code of this example.

    Is is very easy to create a Job and make it visible to normal users.