Development/Tutorials/Plasma/Python/Writing DataEngines - Revision history

Neverendingo: Text replace - "" to ""

2011-06-29T20:54:18Z

Text replace - "</code>" to "</syntaxhighlight>"

Neverendingo: Text replace - "`" to ""`


2011-06-29T20:37:00Z
Text replace - "<code ini>" to "<syntaxhighlight lang="ini">"

				
				
				
				
			
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			Revision as of 20:37, 29 June 2011
			
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  As with applets, DataEngines need the same directory structure (see [[../GettingStarted | the Getting Started tutorial]]), so the first step is to create the appropriate directories. The difference with respect to applets lies in the metadata.desktop file:   As with applets, DataEngines need the same directory structure (see [[../GettingStarted | the Getting Started tutorial]]), so the first step is to create the appropriate directories. The difference with respect to applets lies in the metadata.desktop file:
    
− <code ini> + <syntaxhighlight lang="ini">
  [Desktop Entry]   [Desktop Entry]
  Name=Python Date and Time   Name=Python Date and Time



Neverendingo: Text replace - "" to ""

2011-06-29T20:34:33Z
Text replace - "<code python>" to "<syntaxhighlight lang="python">"

				
				
				
				
			
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			Revision as of 20:34, 29 June 2011
			
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  For this tutorial we'll use the <tt>plasma-dataengine-pytime</tt> code, which is available on KDE's SVN. This DataEngine is an equivalent to the C++ time DataEngine we connected to in the [[../Using DataEngines|using DataEngines tutorial]]. Its function is to display time and date with respect to the current timezone. You can view [http://websvn.kde.org/branches/KDE/4.2/kdebase/workspace/plasma/scriptengines/python/examples/dataengines/pytime/contents/code/main.py?revision=906699&view=markup the main.py file online]. As the file is rather long, we'll take a look at it in sections.   For this tutorial we'll use the <tt>plasma-dataengine-pytime</tt> code, which is available on KDE's SVN. This DataEngine is an equivalent to the C++ time DataEngine we connected to in the [[../Using DataEngines|using DataEngines tutorial]]. Its function is to display time and date with respect to the current timezone. You can view [http://websvn.kde.org/branches/KDE/4.2/kdebase/workspace/plasma/scriptengines/python/examples/dataengines/pytime/contents/code/main.py?revision=906699&view=markup the main.py file online]. As the file is rather long, we'll take a look at it in sections.
    
− <code python> + <syntaxhighlight lang="python">
  # Copyright stuff   # Copyright stuff
    
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  In <tt>__init__</tt> we just initialize the class. In <tt>init()</tt> instead, we set the minimum polling interval, that is  the minimum time (in milliseconds) that needs to pass between one data request (from an applet, for example) and another.   In <tt>__init__</tt> we just initialize the class. In <tt>init()</tt> instead, we set the minimum polling interval, that is  the minimum time (in milliseconds) that needs to pass between one data request (from an applet, for example) and another.
    
− <code python> + <syntaxhighlight lang="python">
  # Continued from above   # Continued from above
       def sources(self):        def sources(self):
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  <tt>sourceRequestEvent</tt> is a function that is called when the applet accesses the DataEngine and requests a specific source (<tt>name</tt>). This function is usually used to make preparations (for example, setting up a connection) before the data can be received. In this case, we simply return <tt>updateSourceEvent</tt> with the source name.   <tt>sourceRequestEvent</tt> is a function that is called when the applet accesses the DataEngine and requests a specific source (<tt>name</tt>). This function is usually used to make preparations (for example, setting up a connection) before the data can be received. In this case, we simply return <tt>updateSourceEvent</tt> with the source name.
    
− <code python> + <syntaxhighlight lang="python">
  # Continued from above   # Continued from above
       def updateSourceEvent(self, tz):        def updateSourceEvent(self, tz):
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  Then, we set the timezone name (for example, "Europe/Rome") into the DataEngine. We also want to get continent and city into the DataEngine, so we split the string into a list with "/" and we check if contains two or more elements. If so, we set the first (for example "Europe") as continent and the second ("Rome") as city. Then the function returns True. <tt>updateSourceEvent</tt> should return True if succesful, and False if otherwise.   Then, we set the timezone name (for example, "Europe/Rome") into the DataEngine. We also want to get continent and city into the DataEngine, so we split the string into a list with "/" and we check if contains two or more elements. If so, we set the first (for example "Europe") as continent and the second ("Rome") as city. Then the function returns True. <tt>updateSourceEvent</tt> should return True if succesful, and False if otherwise.
    
− <code python> + <syntaxhighlight lang="python">
  def CreateDataEngine(parent):   def CreateDataEngine(parent):
       return PyTimeEngine(parent)        return PyTimeEngine(parent)



Nate c: my engine would not work without x-plasma-mainscript pointing to the entry file
2010-07-08T00:14:12Z
my engine would not work without x-plasma-mainscript pointing to the entry file

				
				
				
				
			
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			Revision as of 00:14, 8 July 2010
			
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  ServiceTypes=Plasma/DataEngine   ServiceTypes=Plasma/DataEngine
  X-Plasma-API=python   X-Plasma-API=python
−   + X-Plasma-MainScript=code/main.py
  X-KDE-PluginInfo-Author=Simon Edwards   X-KDE-PluginInfo-Author=Simon Edwards
  X-KDE-PluginInfo-Email=simon@simonzone.com   X-KDE-PluginInfo-Email=simon@simonzone.com



Einar: Crash no longer appears in KDE 4.2.1.
2009-03-07T09:59:35Z
Crash no longer appears in KDE 4.2.1.

				
				
				
				
			
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			Revision as of 09:59, 7 March 2009
			
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  == Problems ==   == Problems ==
    
− Using your own python dataengines is broken in the current Release 4.2.0.  This is fixed in svn and should be backported to 4.2.1 + Using your own python dataengines in KDE 4.2.0 leads to a crash. The problem is fixed in KDE 4.2.1.



Tmske at 09:07, 19 February 2009
2009-02-19T09:07:31Z


				
				
				
				
			
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			Revision as of 09:07, 19 February 2009
			
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  == Problems ==   == Problems ==
    
− Using your own dataengines seems to be broken for the current Release ( min. Kubuntu KDE 4.2 ). If this is not the case, please post the version and remove this part. + Using your own python dataengines is broken in the current Release 4.2.0.  This is fixed in svn and should be backported to 4.2.1



Tampakrap: dataengines broken in 4.2?
2009-02-18T20:16:38Z
dataengines broken in 4.2?

				
				
				
				
			
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			Revision as of 20:16, 18 February 2009
			
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  You can effectively separate presentation and data handling in your applets by creating DataEngines which deal with all the needs for data. In a few lines of code, you can set up your sources, retrieve data and then store it for applets to use.   You can effectively separate presentation and data handling in your applets by creating DataEngines which deal with all the needs for data. In a few lines of code, you can set up your sources, retrieve data and then store it for applets to use.
  + 
  + == Problems ==
  + 
  + Using your own dataengines seems to be broken for the current Release ( min. Kubuntu KDE 4.2 ). If this is not the case, please post the version and remove this part.



Einar: Add missing ")"
2009-01-24T14:38:05Z
Add missing ")"

				
				
				
				
			
			← Older revision
			Revision as of 14:38, 24 January 2009
			
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  == Testing the DataEngine ==   == Testing the DataEngine ==
    
− Run the <tt>plasmaeengineexplorer</tt> application (see [[../Using DataEngines | the Using DataEngines tutorial]] and select the <tt>plasma-dataengine-pytime</tt> DataEngine. If all went well, it will behave in the same manner as the <tt>time</tt> DataEngine.   + Run the <tt>plasmaeengineexplorer</tt> application (see [[../Using DataEngines | the Using DataEngines tutorial]]) and select the <tt>plasma-dataengine-pytime</tt> DataEngine. If all went well, it will behave in the same manner as the <tt>time</tt> DataEngine.
    
  == Conclusion ==   == Conclusion ==
    
  You can effectively separate presentation and data handling in your applets by creating DataEngines which deal with all the needs for data. In a few lines of code, you can set up your sources, retrieve data and then store it for applets to use.   You can effectively separate presentation and data handling in your applets by creating DataEngines which deal with all the needs for data. In a few lines of code, you can set up your sources, retrieve data and then store it for applets to use.



Einar: Concluded. May need more work, of course.
2009-01-24T11:04:41Z
Concluded. May need more work, of course.

				
				
				
				
			
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			Revision as of 11:04, 24 January 2009
			
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  == Conclusion ==   == Conclusion ==
  + 
  + You can effectively separate presentation and data handling in your applets by creating DataEngines which deal with all the needs for data. In a few lines of code, you can set up your sources, retrieve data and then store it for applets to use.





Einar: Add hashes to make sure the functions are properly indented (the first line can't be indented, apparently)
2009-01-24T11:02:23Z
Add hashes to make sure the functions are properly indented (the first line can't be indented, apparently)

				
				
				
				
			
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			Revision as of 11:02, 24 January 2009
			
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  <code python>   <code python>
−   + # Continued from above
       def sources(self):        def sources(self):
           sources = ["Local"]            sources = ["Local"]
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  <code python>   <code python>
  + # Continued from above
       def updateSourceEvent(self, tz):        def updateSourceEvent(self, tz):
           localName = "Local"            localName = "Local"

@@ Line 27: / Line 27: @@
 X-KDE-PluginInfo-License=LGPL
 X-KDE-PluginInfo-EnabledByDefault=true
-</code>
+</syntaxhighlight>
 Take a look at the ServiceType line. When using applets, it was "Plasma/Applet", but since now we're dealing with DataEngines, its value is "Plasma/DataEngine".
@@ Line 48: / Line 48: @@
      def init(self):
          self.setMinimumPollingInterval(333)
-</code>
+</syntaxhighlight>
 We start with the copyright information, followed by importing the required modules (<tt>PyQt4.QtCore</tt> and <tt>plasmascript</tt>). Since we're dealing with time and timezones, we also import <tt>kdecore</tt> to make use of what KDE offers.
@@ Line 63: / Line 63: @@
      def sourceRequestEvent(self, name):
          return self.updateSourceEvent(name)
-</code>
+</syntaxhighlight>
 The <tt>sources()</tt> function is called from applets to request what data sources a DataEngine has (for example, if your applet needs to connect to an online service, the DataEngine could offer a list of suitable services). In this case we first create a list with the "Local" name (which refers to the local time on your computer) and then we extend the list using <tt>KSystemTimeZones.zones().keys()</tt>. This adds the time zones known to KDE to the sources. As a final step, we return this list.
@@ Line 95: / Line 95: @@
          return True
-</code>
+</syntaxhighlight>
 <tt>updateSourceEvent</tt> is the main function needed for a DataEngine, as it takes care of updating and storing the data from a specific source (in our case, <tt>tz</tt>, a timezone). As a first step, we set <tt>localName</tt> to be "Local", and we compare the timezone supplied to the function to it. If they're the same, i.e. local time on the computer, we set the data to current time and date (<tt>QTime.currentTime()</tt> and <tt>QDate.currentDate()</tt>), and then we get the name of the timezone using <tt>KSystemTimeZones.local().name()</tt>.
@@ Line 108: / Line 108: @@
 def CreateDataEngine(parent):
      return PyTimeEngine(parent)
-</code>
+</syntaxhighlight>
 The last two lines deal, in a similar manner as applets, with creating the DataEngine.

← Older revision		Revision as of 09:59, 7 March 2009
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	== Problems ==		== Problems ==

−	Using your own python dataengines ~~is broken~~ in ~~the current Release~~ 4.2.0. ~~This~~ is fixed in ~~svn and should be backported to~~ 4.2.1	+	Using your own python dataengines in KDE 4.2.0 leads to a crash. The problem is fixed in KDE 4.2.1.

← Older revision		Revision as of 09:07, 19 February 2009
Line 131:		Line 131:
	== Problems ==		== Problems ==

−	Using your own dataengines ~~seems to be~~ broken ~~for~~ the current Release ~~( min. Kubuntu KDE~~ 4.2 ). ~~If this~~ is ~~not the case, please post the version~~ and ~~remove this part~~.	+	Using your own python dataengines is broken in the current Release 4.2.0. This is fixed in svn and should be backported to 4.2.1

← Older revision		Revision as of 20:16, 18 February 2009
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	You can effectively separate presentation and data handling in your applets by creating DataEngines which deal with all the needs for data. In a few lines of code, you can set up your sources, retrieve data and then store it for applets to use.		You can effectively separate presentation and data handling in your applets by creating DataEngines which deal with all the needs for data. In a few lines of code, you can set up your sources, retrieve data and then store it for applets to use.
		+
		+	== Problems ==
		+
		+	Using your own dataengines seems to be broken for the current Release ( min. Kubuntu KDE 4.2 ). If this is not the case, please post the version and remove this part.

← Older revision		Revision as of 11:04, 24 January 2009
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	== Conclusion ==		== Conclusion ==
		+
		+	You can effectively separate presentation and data handling in your applets by creating DataEngines which deal with all the needs for data. In a few lines of code, you can set up your sources, retrieve data and then store it for applets to use.