PyQt Tips and Tricks - Revision history

amigadave: /* Tips and Tricks */ move content from PyQt instant startup screen trick

amigadave — Tue, 31 May 2011 09:44:28 GMT

Tips and Tricks: move content from PyQt instant startup screen trick

← Older revision		Revision as of 09:44, 31 May 2011
Line 91:		Line 91:
	</source>		</source>
	[http://talk.maemo.org/showpost.php?p=714507&postcount=1]		[http://talk.maemo.org/showpost.php?p=714507&postcount=1]
		+
		+	=== Instant startup screen ===
		+
		+	As most of us already know most PyQt4 apps are taking quite sometimes at start up and most of the time users are getting initial black screen while it's loading, this is just not only the case with Python apps but all the apps on [[Nokia N900\|N900]]. Nokia has used a trick to snapshot of apps start up screen and load image instantly when the app icon is pressed, which give users an impression that apps was started up instantly but in reality they were not. (modest, note, sketch, control panel, application manager, pdfviewer, worldclock, xterm, and calculator are using this trick). So why don't we apply the same trick on our apps to make it look fast at startup? Well, Most of us don't even know the trick is there and some debates whether this is a good idea or not, but I for one rather see a false startup image than a black screen. So below is the instruction to make your Python Qt app fly at startup on N900 device.
		+
		+	'''There are three basic things to make it work:'''
		+
		+	<ol>
		+	<li>
		+	A D-Bus service file (name whatever e.g. yourapp.service) in "<code>/usr/share/dbus-1/services/</code>" folder even though yourapp is not using D-Bus related service at all and it should look like this format in <code>yourapp.service</code>.
		+	<pre>
		+	[D-BUS Service]
		+	Name=what.ever.yourapp
		+	Exec=/opt/yourapp/main.py
		+	</pre>
		+	</li>
		+	<li>
		+	Adding "<code>X-Osso-Service=what.ever.yourapp</code>" in your yourapp.desktop file in "<code>/usr/share/applications/hildon/</code>" folder, something like this.
		+	<pre>
		+	[Desktop Entry]
		+	Encoding=UTF-8
		+	Version=1.0
		+	Type=Application
		+	Terminal=false
		+	Name=YourApp
		+	Icon=YourApp
		+	Exec=/opt/yourapp/main.py
		+	X-Osso-Service=what.ever.yourapp
		+	</pre>
		+	</li>
		+	<li>
		+	Lastly, A function code in your app to take a snapshot of your app startup screen when it starts up the first time or when it exits whichever your prefer. Below is an basic example of PyQt4 app code which take a snapshot of the screen at start up if it's not already exist and save it into '"<code>/home/user/.cache/launch/what.ever.yourapp.pvr</code>" (p.s. the file name has to match with your <code>X-Osso-Service</code>, and D-BUS Service Name plus .pvr extension).
		+	<source lang="python">
		+	#!/usr/bin/env python2.5
		+	# -- coding: utf-8 --
		+
		+	from PyQt4.QtGui import *
		+	from PyQt4.QtCore import *
		+
		+	import osso # only needed for osso_initialize
		+
		+	class MainWindow(QMainWindow):
		+	def __init__(self, parent = None):
		+	self.dbus_service_name = "what.ever.yourapp" #must be the same as your X-osso-service in yourapp.desktop file
		+	"""
		+	self.osso_c = osso.Context(self.dbus_service_name, "0.0.1", False)
		+	is only needed if your app is not launched from run-standalone.sh,
		+	Otherwise, your app will be terminated after ~ 2mins running
		+	don't ask me why :)
		+	"""
		+	self.osso_c = osso.Context(self.dbus_service_name, "0.0.1", False)
		+
		+	QMainWindow.__init__(self, parent)
		+
		+	self.centralwidget = QWidget(self)
		+	self.setCentralWidget(self.centralwidget)
		+
		+	"""
		+	the rest of your code here....
		+	"""
		+
		+	def takeScreenShot(self):
		+	pvr = "/home/user/.cache/launch/%s.pvr" % self.dbus_service_name
		+	if not QFile.exists(pvr): # skipped if it's already there
		+	QPixmap.grabWidget(self.centralwidget).save(pvr, 'png') # tell it to grab only your self.centralwidget screen, which is just window screen without the menu status bar on top.
		+
		+	if __name__ == '__main__':
		+	import sys
		+	app = QApplication(sys.argv)
		+	app.setApplicationName("YourAppName")
		+	YourApp = MainWindow()
		+	YourApp.show()
		+	YourApp.takeScreenShot() # run this after the YourApp.show()
		+	sys.exit(app.exec_())
		+	</source>
		+	</li>
		+	</ol>

	== Example Applications ==		== Example Applications ==

amigadave: add link

amigadave — Fri, 12 Nov 2010 13:41:45 GMT

add link

← Older revision		Revision as of 13:41, 12 November 2010
Line 1:		Line 1:
-	With ~~Meego~~ there is a lot of interest in developing applications in Qt rather than GTK. This page spawned from a [http://talk.maemo.org/showthread.php?t=56171 discussion thread].	+	With MeeGo there is a lot of interest in [[Qt4 development\|developing applications in Qt]] rather than GTK+. This page spawned from a [http://talk.maemo.org/showthread.php?t=56171 discussion thread].

	== Tips and Tricks ==		== Tips and Tricks ==

epage: Adding a performance note and a note for working with QThread

epage — Sat, 11 Sep 2010 17:18:43 GMT

Adding a performance note and a note for working with QThread

← Older revision		Revision as of 17:18, 11 September 2010
Line 2:		Line 2:

	== Tips and Tricks ==		== Tips and Tricks ==
		+
		+	=== Qt-Specific Performance Considerations ===
		+
		+	Riverbank claims[http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/pyqt4ref.html#the-qtcore-pyqtslot-decorator] that decorating slots with pyqtSlot is faster and reduces memory.
		+
		+	Example:
		+	<source lang="python">
		+	@QtCore.pyqtSlot(int)
		+	@QtCore.pyqtSlot('QString')
		+	def valueChanged(self, value):
		+	""" Two slots will be defined in the QMetaObject. """
		+	</source>
		+
		+	Notes:
		+	* Unverified for PyQt
		+	* Unsure if this applies to PySide

	=== Identifying the Sender of a Signal ===		=== Identifying the Sender of a Signal ===
Line 43:		Line 59:

	It is discouraged to inherit from <code>QThread</code> and to use <code>moveToThread</code> on the <code>QThread</code>.[http://labs.trolltech.com/blogs/2010/06/17/youre-doing-it-wrong]. A C++ example of how to use these is shown in a producer/consumer style application can be found on the [http://labs.trolltech.com/blogs/2006/12/04/threading-without-the-headache/ trolltech blog].		It is discouraged to inherit from <code>QThread</code> and to use <code>moveToThread</code> on the <code>QThread</code>.[http://labs.trolltech.com/blogs/2010/06/17/youre-doing-it-wrong]. A C++ example of how to use these is shown in a producer/consumer style application can be found on the [http://labs.trolltech.com/blogs/2006/12/04/threading-without-the-headache/ trolltech blog].
		+
		+	Note: The "You're Doing it Wrong" post claims run now has a default implementation to call exec_. As of python-qt 4.7 on Ubuntu 10.04 epage is not seeing this and had to create a class that inherits from QThread and provides that behavior.

	==== import threading ====		==== import threading ====

92.37.50.23: /* Stacked Windows */

92.37.50.23 — Sun, 18 Jul 2010 10:10:23 GMT

Stacked Windows

← Older revision		Revision as of 10:10, 18 July 2010
Line 61:		Line 61:

	<source lang="python">		<source lang="python">
-	class ~~showWindowQtGui~~.QMainWindow):	+	class showWindow(QtGui.QMainWindow):
	def __init__(self, parent=None):		def __init__(self, parent=None):
	QtGui.QWidget.__init__(self, parent)		QtGui.QWidget.__init__(self, parent)

amigadave: wikify slightly

amigadave — Fri, 18 Jun 2010 08:19:42 GMT

wikify slightly

← Older revision		Revision as of 08:19, 18 June 2010
Line 1:		Line 1:
	With Meego there is a lot of interest in developing applications in Qt rather than GTK. This page spawned from a [http://talk.maemo.org/showthread.php?t=56171 discussion thread].		With Meego there is a lot of interest in developing applications in Qt rather than GTK. This page spawned from a [http://talk.maemo.org/showthread.php?t=56171 discussion thread].

-	= Tips and Tricks =	+	== Tips and Tricks ==

-	== Identifying the Sender of a Signal ==	+	=== Identifying the Sender of a Signal ===

-	There are two main approaches for this. The first is to wrap the slot with a lambda to pass in any additional arguments	+	There are two main approaches for this. The first is to wrap the slot with a lambda to pass in any additional arguments:
	<source lang="python">		<source lang="python">
	def notifyMe(foo)		def notifyMe(foo)
Line 18:		Line 18:
	The second and more general solution is to use the [http://pysnippet.blogspot.com/2010/06/qsignalmapper-at-your-service.html QSignalMapper][http://talk.maemo.org/showpost.php?p=714752&postcount=8]		The second and more general solution is to use the [http://pysnippet.blogspot.com/2010/06/qsignalmapper-at-your-service.html QSignalMapper][http://talk.maemo.org/showpost.php?p=714752&postcount=8]

-	== Learning to use Qt CSS ==	+	=== Learning to use Qt CSS ===

	Much like web development, [http://doc.qt.nokia.com/4.6/stylesheet.html CSS is also available within Qt]. [http://doc.qt.nokia.com/4.6/stylesheet-examples.html There's a list of examples] that can be tried out just using Qt Designer. If you're using custom CSS, using [http://agateau.wordpress.com/2008/01/15/qt-stylesheets-and-qpalette/ palette() in your CSS definitions] will allow you to use colors that the theme already knows about. As an example, this is an easy way to get the default blue color on your buttons when you want that color.		Much like web development, [http://doc.qt.nokia.com/4.6/stylesheet.html CSS is also available within Qt]. [http://doc.qt.nokia.com/4.6/stylesheet-examples.html There's a list of examples] that can be tried out just using Qt Designer. If you're using custom CSS, using [http://agateau.wordpress.com/2008/01/15/qt-stylesheets-and-qpalette/ palette() in your CSS definitions] will allow you to use colors that the theme already knows about. As an example, this is an easy way to get the default blue color on your buttons when you want that color.
Line 24:		Line 24:
	Depending on your needs, there's a number of [http://doc.trolltech.com/4.4/stylesheet-reference.html#list-of-icons built-in icons] that are available for use.[http://talk.maemo.org/showpost.php?p=714507&postcount=1]		Depending on your needs, there's a number of [http://doc.trolltech.com/4.4/stylesheet-reference.html#list-of-icons built-in icons] that are available for use.[http://talk.maemo.org/showpost.php?p=714507&postcount=1]

-	Style sheets and the native QMaemo5Style do not mix very well, since Maemo 5 lays out and draws some widgets very differently (e.g. QRadioButton). We recommend using local style sheets on specific widgets only, instead of setting one via QApplication::setStyleSheet().[http://talk.maemo.org/showpost.php?p=714544&postcount=4]	+	Style sheets and the native <code>QMaemo5Style</code> do not mix very well, since Maemo 5 lays out and draws some widgets very differently (e.g. <code>QRadioButton</code>). We recommend using local style sheets on specific widgets only, instead of setting one via <code>QApplication::setStyleSheet()</code>.[http://talk.maemo.org/showpost.php?p=714544&postcount=4]

-	== QString and Python ==	+	=== QString and Python ===

-	I've had some ~~unicode~~-~~relate~~ issues when moving strings between ~~python~~ datatypes and Qt datatypes. Somehow, the ~~unicode~~ stuff would get lost. So, it's likely easiest (At least when you're new to ~~python~~ and Qt) to use QString and QStringList than their pure ~~python~~ counterparts.	+	I've had some Unicode-related issues when moving strings between Python datatypes and Qt datatypes. Somehow, the Unicode stuff would get lost. So, it's likely easiest (At least when you're new to Python and Qt) to use <code>QString</code> and <code>QStringList</code> than their pure Python counterparts.

-	If you're not bringing in data from anywhere else, this isn't that big of a deal, but if you're interacting with data from any other source, ~~unicode~~ is a pretty likely scenario these days.[http://talk.maemo.org/showpost.php?p=717579&postcount=11]	+	If you're not bringing in data from anywhere else, this isn't that big of a deal, but if you're interacting with data from any other source, Unicode is a pretty likely scenario these days.[http://talk.maemo.org/showpost.php?p=717579&postcount=11]

-	Just to note that, in my experience, locales fail to work with PyQt - QTextCodec.codecForLocale() does not return the correct codec, which also means QString's toLocal8Bit() and fromLocal8Bit() fail.	+	Just to note that, in my experience, locales fail to work with PyQt - <code>QTextCodec.codecForLocale()</code> does not return the correct codec, which also means <code>QString</code>'s <code>toLocal8Bit()</code> and <code>fromLocal8Bit()</code> fail.

-	The ~~python~~ locale stuff works fine, but then you have the joy of converting between QString and ~~python~~ strings (which works perfectly when it does it implicitly, but an explicit conversion seems to go via ASCII unless you specifically tell it to use ~~utf~~-8 instead). [http://talk.maemo.org/showpost.php?p=717585&postcount=12]	+	The Python locale stuff works fine, but then you have the joy of converting between <code>QString</code> and Python strings (which works perfectly when it does it implicitly, but an explicit conversion seems to go via ASCII unless you specifically tell it to use UTF-8 instead). [http://talk.maemo.org/showpost.php?p=717585&postcount=12]

-	== Qt and Threads ==	+	=== Qt and Threads ===

-	There are multiple options for preemptive threading and cooperative threading. The big question is QThread or threading.Thread. This has been discussed on the [http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16050.html PyQt mailing list] and [http://stackoverflow.com/questions/1595649/threading-in-a-pyqt-application-use-qt-threads-or-python-threads SO]	+	There are multiple options for preemptive threading and cooperative threading. The big question is <code>QThread</code> or <code>threading.Thread</code>. This has been discussed on the [http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16050.html PyQt mailing list] and [http://stackoverflow.com/questions/1595649/threading-in-a-pyqt-application-use-qt-threads-or-python-threads SO]

-	=== QThread ===	+	==== QThread ====

-	It is discouraged to inherit from QThread and to use moveToThread on the QThread.[http://labs.trolltech.com/blogs/2010/06/17/youre-doing-it-wrong]. A C++ example of how to use these is shown in a producer/consumer style application can be found on the [http://labs.trolltech.com/blogs/2006/12/04/threading-without-the-headache/ trolltech blog].	+	It is discouraged to inherit from <code>QThread</code> and to use <code>moveToThread</code> on the <code>QThread</code>.[http://labs.trolltech.com/blogs/2010/06/17/youre-doing-it-wrong]. A C++ example of how to use these is shown in a producer/consumer style application can be found on the [http://labs.trolltech.com/blogs/2006/12/04/threading-without-the-headache/ trolltech blog].

-	=== import threading ===	+	==== import threading ====

-	It appears QThread initializes some TLS for data essential for thread safe signals and slots. Also when creating cross-thread signals it queues the signal emission rather than doing it immediately. These present problems when wanting to use the native Python Threading in a Qt application.[http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16062.html][http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16082.html]	+	It appears <code>QThread</code> initializes some TLS for data essential for thread safe signals and slots. Also when creating cross-thread signals it queues the signal emission rather than doing it immediately. These present problems when wanting to use the native Python Threading in a Qt application.[http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16062.html][http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16082.html]

	If the Python thread would not interact directly with Qt then using Python threads is fine without any consideration.		If the Python thread would not interact directly with Qt then using Python threads is fine without any consideration.

-	Sometimes you must use Python threads with Qt like when porting applications. One solution to ~~his~~ is to pump messages into a queue and have an QTimer poll the queue periodically for tasks to process in the UI thread.[http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16062.html]	+	Sometimes you must use Python threads with Qt like when porting applications. One solution to this is to pump messages into a queue and have an <code>QTimer</code> poll the queue periodically for tasks to process in the UI thread.[http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16062.html]

-	=== QTimer ===	+	==== QTimer ====

-	Spread the work across multiple callbacks to allow the UI to remain responsive. See multiple [http://www.rkblog.rk.edu.pl/w/p/qtimer-making-timers-pyqt4/ QTimer types]. If you're not relying on third parties (anything that will block the interpreter - whether it be waiting on hardware or a call via XMLRPC) ~~QTimers~~ are probably a good choice.	+	Spread the work across multiple callbacks to allow the UI to remain responsive. See multiple [http://www.rkblog.rk.edu.pl/w/p/qtimer-making-timers-pyqt4/ QTimer types]. If you're not relying on third parties (anything that will block the interpreter - whether it be waiting on hardware or a call via XMLRPC) <code>QTimer</code>s are probably a good choice.

-	As an example, I wrote an app that would play a series of .jpg images as a movie in a player. While using a thread would work, using a QTimer worked great as well, since there was no waiting for hardware.	+	As an example, I wrote an app that would play a series of .jpg images as a movie in a player. While using a thread would work, using a <code>QTimer</code> worked great as well, since there was no waiting for hardware.

-	== Stacked Windows ==	+	=== Stacked Windows ===

	<source lang="python">		<source lang="python">
Line 74:		Line 74:
	[http://talk.maemo.org/showpost.php?p=714507&postcount=1]		[http://talk.maemo.org/showpost.php?p=714507&postcount=1]

-	= Example Applications =	+	== Example Applications ==
		+
	This is an overview of some of the PyQt applications available for Maemo. For some of the apps, there's a brief outline of unique functions they might have that you might want for your app.		This is an overview of some of the PyQt applications available for Maemo. For some of the apps, there's a brief outline of unique functions they might have that you might want for your app.

-	The official [http://www.riverbankcomputing.co.uk/software/pyqt/download PyQt] bindings come with ~~python~~-based examples for many things. There's also examples for [http://maemo.org/packages/view/python2.5-qt4-doc/ PyQt on ~~Maemo5~~] with ~~python~~ examples, as well.	+	The official [http://www.riverbankcomputing.co.uk/software/pyqt/download PyQt] bindings come with Python-based examples for many things. There's also examples for [http://maemo.org/packages/view/python2.5-qt4-doc/ PyQt on Maemo 5] with Python examples, as well.

	If you want to learn to become better in Python and Qt, reading code is one of the better ways to do it.		If you want to learn to become better in Python and Qt, reading code is one of the better ways to do it.
Line 88:		Line 89:
	* [http://maemo.org/packages/view/maelophone/ maelophone]		* [http://maemo.org/packages/view/maelophone/ maelophone]
	* [http://maemo.org/packages/view/healthcheck/ healthcheck]		* [http://maemo.org/packages/view/healthcheck/ healthcheck]
-	** Gives examples of interacting with much of the hardware on the ~~n900~~	+	** Gives examples of interacting with much of the hardware on the N900
	* [http://maemo.org/packages/view/qlister/ qlister]		* [http://maemo.org/packages/view/qlister/ qlister]
	* Gonvert (1.0+)		* Gonvert (1.0+)
Line 98:		Line 99:
	** Threading and Qt		** Threading and Qt

-	= Web Resources =	+	== Web Resources ==

-	* [http://doc.qt.nokia.com/qt-maemo-4.6/index.html Maemo Version of the QT Documentation]	+	* [http://doc.qt.nokia.com/qt-maemo-4.6/index.html Maemo Version of the Qt Documentation]
	* [http://doc.qt.nokia.com/qt-maemo-4.6/platform-notes-maemo5.html Maemo-specific platform notes]		* [http://doc.qt.nokia.com/qt-maemo-4.6/platform-notes-maemo5.html Maemo-specific platform notes]
	* [http://talk.maemo.org/showthread.php?t=42754 PyQt4 Demo's and Documentation Packages]		* [http://talk.maemo.org/showthread.php?t=42754 PyQt4 Demo's and Documentation Packages]
Line 106:		Line 107:
	[[Category:Qt]]		[[Category:Qt]]
	[[Category:Python]]		[[Category:Python]]
		+	[[Category:Development]]

epage: /* QThread */

epage — Thu, 17 Jun 2010 18:30:43 GMT

QThread

← Older revision		Revision as of 18:30, 17 June 2010
Line 41:		Line 41:

	=== QThread ===		=== QThread ===
		+
		+	It is discouraged to inherit from QThread and to use moveToThread on the QThread.[http://labs.trolltech.com/blogs/2010/06/17/youre-doing-it-wrong]. A C++ example of how to use these is shown in a producer/consumer style application can be found on the [http://labs.trolltech.com/blogs/2006/12/04/threading-without-the-headache/ trolltech blog].

	=== import threading ===		=== import threading ===

timconradinc: /* Example Applications */

timconradinc — Thu, 17 Jun 2010 14:31:37 GMT

Example Applications

← Older revision		Revision as of 14:31, 17 June 2010
Line 74:		Line 74:
	= Example Applications =		= Example Applications =
	This is an overview of some of the PyQt applications available for Maemo. For some of the apps, there's a brief outline of unique functions they might have that you might want for your app.		This is an overview of some of the PyQt applications available for Maemo. For some of the apps, there's a brief outline of unique functions they might have that you might want for your app.
		+
		+	The official [http://www.riverbankcomputing.co.uk/software/pyqt/download PyQt] bindings come with python-based examples for many things. There's also examples for [http://maemo.org/packages/view/python2.5-qt4-doc/ PyQt on Maemo5] with python examples, as well.

	If you want to learn to become better in Python and Qt, reading code is one of the better ways to do it.		If you want to learn to become better in Python and Qt, reading code is one of the better ways to do it.

timconradinc: /* Example Applications */

timconradinc — Thu, 17 Jun 2010 14:25:54 GMT

Example Applications

← Older revision		Revision as of 14:25, 17 June 2010
Line 73:		Line 73:

	= Example Applications =		= Example Applications =
		+	This is an overview of some of the PyQt applications available for Maemo. For some of the apps, there's a brief outline of unique functions they might have that you might want for your app.

-	* ncalc	+	If you want to learn to become better in Python and Qt, reading code is one of the better ways to do it.
-	* nclock	+
-	* maesynth	+	* [http://maemo.org/packages/view/ncalc/ ncalc]
-	** Uses QGraphicsView	+	* [http://maemo.org/packages/view/nclock/ nclock]
-	* maelophone	+	* [http://maemo.org/packages/view/maesynth/ maesynth]
-	* healthcheck	+	** Uses QGraphicsView to create a non-standard looking GUI
-	* qlister	+	** Also plays sounds when keys are pressed
		+	* [http://maemo.org/packages/view/maelophone/ maelophone]
		+	* [http://maemo.org/packages/view/healthcheck/ healthcheck]
		+	** Gives examples of interacting with much of the hardware on the n900
		+	* [http://maemo.org/packages/view/qlister/ qlister]
	* Gonvert (1.0+)		* Gonvert (1.0+)
	* [http://maemo.org/packages/view/wifieye/ WifiEye]		* [http://maemo.org/packages/view/wifieye/ WifiEye]
	* [http://maemo.org/packages/view/maegirls/ MaeGirls]		* [http://maemo.org/packages/view/maegirls/ MaeGirls]
-	* pyPianobar	+	* [http://maemo.org/packages/view/pypianobar/ pyPianobar]
	** Threading and Qt		** Threading and Qt
-	* pyRadio	+	* [http://maemo.org/packages/view/pyradio/ pyRadio]
	** Threading and Qt		** Threading and Qt

timconradinc: /* QTimer */

timconradinc — Thu, 17 Jun 2010 14:12:22 GMT

QTimer

← Older revision		Revision as of 14:12, 17 June 2010
Line 52:		Line 52:
	=== QTimer ===		=== QTimer ===

-	Spread the work across multiple callbacks to allow the UI to remain responsive. See multiple [http://www.rkblog.rk.edu.pl/w/p/qtimer-making-timers-pyqt4/ QTimer types]	+	Spread the work across multiple callbacks to allow the UI to remain responsive. See multiple [http://www.rkblog.rk.edu.pl/w/p/qtimer-making-timers-pyqt4/ QTimer types]. If you're not relying on third parties (anything that will block the interpreter - whether it be waiting on hardware or a call via XMLRPC) QTimers are probably a good choice.
		+
		+	As an example, I wrote an app that would play a series of .jpg images as a movie in a player. While using a thread would work, using a QTimer worked great as well, since there was no waiting for hardware.

	== Stacked Windows ==		== Stacked Windows ==

epage: /* import threading */

epage — Thu, 17 Jun 2010 13:58:04 GMT

import threading

← Older revision		Revision as of 13:58, 17 June 2010
Line 43:		Line 43:

	=== import threading ===		=== import threading ===
		+
		+	It appears QThread initializes some TLS for data essential for thread safe signals and slots. Also when creating cross-thread signals it queues the signal emission rather than doing it immediately. These present problems when wanting to use the native Python Threading in a Qt application.[http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16062.html][http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16082.html]
		+
		+	If the Python thread would not interact directly with Qt then using Python threads is fine without any consideration.
		+
		+	Sometimes you must use Python threads with Qt like when porting applications. One solution to his is to pump messages into a queue and have an QTimer poll the queue periodically for tasks to process in the UI thread.[http://www.mail-archive.com/pyqt@riverbankcomputing.com/msg16062.html]

	=== QTimer ===		=== QTimer ===