[PyQt] QDialog's widgets do not show up correctly

[Phil Thompson]

On Sun, 6 Jul 2008 17:19:30 +0200, Christoph Schmidt <ch_schmidt at online.de>
wrote:
> Hi,
> 
> I'm currently learning programming with PyQt and play around a bit with 
> python-apt + PyQt4. My problem is as follows: In order to indicate the 
> progress of an apt operation, python-apt offers the possibility to pass
an
> 
> instance of a progress class. In this case I subclassed FetchProgress
from
> 
> apt.progress:
> 
> class GuiUpdateProgress(QDialog, FetchProgress):
>     def __init__(self, parent=None):
> 	QDialog.__init__(self, parent)
> 	FetchProgress.__init__(self)
> 	self.items = {}
> 	self.setModal(True)
> 	self.fetchIndicator = QProgressBar()
> 	self.speedIndicator = QLabel("Unknown")
> 	self.layout = QVBoxLayout()
> 	self.layout.addWidget(self.fetchIndicator)
> 	self.layout.addWidget(self.speedIndicator)
> 	self.setLayout(self.layout)
>     
>     def start(self):
> 	self.show()
>     
>     def stop(self):
>         if 2 in self.items.values():
> 	    QMessageBox.warning(self, "Update Error",
>                                   "One or more sources could not be
> updated!")
> 	self.hide()
>     
>     def updateStatus(self, uri, descr, shortDescr, status):
> 	self.items[uri] = status   # unimportant
> 
>     def pulse(self):
> 	self.percent = ((self.currentBytes + self.currentItems)*100.0) /
>                                  float(self.totalBytes + self.totalItems)
>         if self.currentCPS > 0:
>             self.eta = (self.totalBytes-self.currentBytes) /
>                              float(self.currentCPS)
> 	self.fetchIndicator.setValue(int(self.percent))
> 	self.speedIndicator.setText(str(self.eta))
> 	return True
>     
>     def mediaChange(self, medium, drive):
> 	pass   # unimportant
> 
> When I now pass an instance of this class to a python-apt operation, at
> first 
> start() is called, then updateStatus() and pulse() are being called 
> repeatedly until the operation is done and stop() is called in the end.
> 
> I would expect this code to let a QDialog pop up, show its initial state
> when 
> start() is called and update whenever pulse() is called. However, it
seems
> to 
> only show an empty window before pulse() is called the first time, and
> even 
> when pulse() is called, only the QProgressBar updates itself, the QLabel 
> stays invisible.
> 
> I uploaded the a tstable version of the code at
> http://pastebin.com/f3caddde3 
> to show you what I mean (python-apt is required). My PyQt Version is 
> (according to Synaptic) 4.3.3.
> 
> I hope somebody can tell me what I am doing wrong.

Modal dialogs have their own event loop. You probably need to call the
dialog's exec_() method.

Phil