Development/Tutorials/Plasma/DataEngines - Revision history

AnneW at 15:33, 15 July 2012

2012-07-15T15:33:08Z

Nicolas17: monospacing identifiers

2011-06-27T19:36:01Z

monospacing identifiers

Nicolas17: update to new syntaxhighlighter

2011-06-27T19:32:14Z

update to new syntaxhighlighter

Nicolas17: whitespace fixes

2011-06-25T01:35:33Z

whitespace fixes

Nicolas17: Remove 'Abstract' heading, make the text appear as intro paragraph instead

2011-06-25T01:35:05Z

Remove 'Abstract' heading, make the text appear as intro paragraph instead

Bille: expand a comment

2011-06-07T14:50:55Z

expand a comment

Odysseus at 23:43, 19 March 2011

2011-03-19T23:43:27Z

Camilasan at 20:24, 17 January 2011

2011-01-17T20:24:54Z

Bille: update how to restart plasma

2010-08-19T14:31:44Z

update how to restart plasma

Sreich: explain alternative to polling

2010-04-19T18:15:58Z

explain alternative to polling

← Older revision		Revision as of 15:33, 15 July 2012
Line 1:		Line 1:
−	~~{{Template:I18n/Language Navigation Bar\|Development/Tutorials/Plasma/DataEngines}}~~

	{{TutorialBrowser\|		{{TutorialBrowser\|

@@ Line 65: / Line 65: @@
 The most important bits are:
-* the Name, Comment and Type fields, which are required for all desktop files
+* the <tt>Name</tt>, <tt>Comment</tt> and <tt>Type</tt> fields, which are required for all desktop files
-* the X-KDE-ServiceTypes field, which tells plasma that this is a data engine
+* the <tt>X-KDE-ServiceTypes</tt> field, which tells plasma that this is a data engine
-* the X-KDE-Library field, which tells plasma how to load the data engine - in this case by loading plasma_engine_testtime.so from the plugin folder
+* the <tt>X-KDE-Library</tt> field, which tells plasma how to load the data engine - in this case by loading <tt>plasma_engine_testtime.so</tt> from the plugin folder
-* the X-Plasma-EngineName field, which tells plasma what the exported plugin name is (as given to K_EXPORT_PLASMA_DATAENGINE)
+* the <tt>X-Plasma-EngineName</tt> field, which tells plasma what the exported plugin name is (as given to <tt>K_EXPORT_PLASMA_DATAENGINE</tt>)
-* the X-KDE-PluginInfo-Name is important for DataEngines since 4.2, without it, plasma will not find your DataEngine
+* the <tt>X-KDE-PluginInfo-Name</tt> is important for DataEngines since 4.2, without it, plasma will not find your DataEngine

@@ Line 24: / Line 24: @@
 A very useful tool for anyone writing data engines is the Plasma engine explorer.  You can use it to see how the time data engine should work now by running
-<code bash>
+<syntaxhighlight lang="bash">
 plasmaengineexplorer
-</code>
+</syntaxhighlight>
 Near the top of the window is a drop-down box for selecting a data engine.  Choose the "time" engine.  You can now request a source.  Try requesting the "Local" source, with an update interval of 500ms (twice a second).  A single item, Local, should be visible in the sources list.  Click the + on the left to expand it, and you should get the date, time, timezone, timezone continent and timezone city listed, together with the type for each.
@@ Line 44: / Line 44: @@
 '''plasma-engine-testtime.desktop'''
-<code ini>
+<syntaxhighlight lang="ini">
 [Desktop Entry]
 Name=Test Time Engine
@@ Line 62: / Line 62: @@
 X-KDE-PluginInfo-License=LGPL
 X-KDE-PluginInfo-EnabledByDefault=true
-</code>
+</syntaxhighlight>
 The most important bits are:
@@ Line 75: / Line 75: @@
 '''testtimeengine.h'''
-<code cppqt>
+<syntaxhighlight lang="cpp-qt">
 // the following header is required by the LGPL because
 // we are using the actual time engine code
@@ Line 132: / Line 132: @@
 #endif // TESTTIMEENGINE_H
-</code>
+</syntaxhighlight>
 A separate header file may seem a bit pointless for a plugin this small, but it is a good habit to get into.
@@ Line 142: / Line 142: @@
 '''testtimeengine.cpp'''
-<code cppqt>
+<syntaxhighlight lang="cpp-qt">
 // the following header is required by the LGPL because
 // we are using the actual time engine code
@@ Line 227: / Line 227: @@
 // this is needed since TestTimeEngine is a QObject
 #include "testtimeengine.moc"
-</code>
+</syntaxhighlight>
@@ Line 270: / Line 270: @@
 The CMakeLists.txt file tells CMake how to build your plugin.  The following file will work for this project:
-<code bash>
+<syntaxhighlight lang="bash">
 # A name for the project
 project(plasma-testtime)
@@ Line 299: / Line 299: @@
 install(FILES plasma-engine-testtime.desktop
          DESTINATION ${SERVICES_INSTALL_DIR})
-</code>
+</syntaxhighlight>
@@ Line 305: / Line 305: @@
 Run
-<code bash>
+<syntaxhighlight lang="bash">
 cmake -DCMAKE_BUILD_TYPE=debugfull -DCMAKE_INSTALL_PREFIX=$KDEDIR
 make
 make install
-</code>
+</syntaxhighlight>
 Replace <tt>$KDEDIR</tt> with your kde installation directory if <tt>$KDEDIR</tt> is not set.
 Alternatively, you can run the following
-<code bash>
+<syntaxhighlight lang="bash">
 cmake -DCMAKE_BUILD_TYPE=debugfull
 make
 cp ./lib/plasma_engine_testtime.so $KDEDIR/lib/kde4
 cp ./plasma-engine-testtime.desktop $KDEDIR/share/kde4/services/
-</code>
+</syntaxhighlight>
 Now run <tt>kbuildsycoca4</tt> to tell KDE applications (including plasma and the plasma engine explorer) about the new desktop file.
 Now you can test it as we did the time engine.  Run
-<code bash>
+<syntaxhighlight lang="bash">
 plasmaengineexplorer --engine testtime
-</code>
+</syntaxhighlight>
 Note that if you change a data engine (or applet), the change will not register in any running applications.  After modifying and reinstalling a data engine, to make plasma register the change you must run
-<code bash>
+<syntaxhighlight lang="bash">
 kbuildsycoca4
 kquitapp plasma-desktop (or plasma-netbook, etc)
 plasma-desktop
-</code>
+</syntaxhighlight>

@@ Line 13: / Line 13: @@
 reading=[http://api.kde.org/4.x-api/kdelibs-apidocs/plasma/html/classPlasma_1_1DataEngine.html DataEngine API], [[Development/Tutorials/CMake|CMake Tutorials]], [[Development/Tutorials/Plasma/GettingStarted|Writing a Plasmoid (Tutorial)]]
 }}
 DataEngines provide a standardized interface to various data sources for visualizations to use.
@@ Line 19: / Line 20: @@
 The time data engine provides the current date and time for any timezone that the system knows about.  It is used by every one of the many clock plasmoids.  The obvious benefit of this is that there is no need to reimplement the logic for selecting timezones in every clock plasmoid.
 ==The Plasma Engine Explorer==

@@ Line 13: / Line 13: @@
 reading=[http://api.kde.org/4.x-api/kdelibs-apidocs/plasma/html/classPlasma_1_1DataEngine.html DataEngine API], [[Development/Tutorials/CMake|CMake Tutorials]], [[Development/Tutorials/Plasma/GettingStarted|Writing a Plasmoid (Tutorial)]]
 }}
 DataEngines provide a standardized interface to various data sources for visualizations to use.

@@ Line 225: / Line 225: @@
 // this plugin.  The first argument must match
 // the X-Plasma-EngineName in the .desktop file.
 K_EXPORT_PLASMA_DATAENGINE(testtime, TestTimeEngine)

@@ Line 7: / Line 7: @@
 name=Writing a Data Engine|
-pre=[http://mindview.net/Books/TICPP/ThinkingInCPP2e.html C++], [http://www.trolltech.com/products/qt/ Qt], [[Getting_Started/Build/KDE4|KDE4 development environment]]|
+pre=[http://mindview.net/Books/TICPP/ThinkingInCPP2e.html C++], [http://www.trolltech.com/products/qt/ Qt], [[Getting_Started/Build|KDE development environment]]|
 next=|

← Older revision		Revision as of 20:24, 17 January 2011
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		+	{{Template:I18n/Language Navigation Bar\|Development/Tutorials/Plasma/DataEngines}}
		+
	{{TutorialBrowser\|		{{TutorialBrowser\|

← Older revision		Revision as of 18:15, 19 April 2010
Line 245:		Line 245:
	====Responding to Outside Events====		====Responding to Outside Events====

−	Polling does not make sense for all engines. Some engines, such as the device engine, respond to outside events. You can use <tt>setData()</tt> at any time to create or update a source. <tt>removeData()</tt> and <tt>removeSource()</tt> are also useful methods.	+	Polling does not make sense for all engines. Some engines, such as the device engine, respond to outside events. You can use <tt>setData()</tt> at any time to create or update a source. <tt>removeData()</tt> and <tt>removeSource()</tt> are also useful methods. For the applets that want to be informed when the sources change, without using polling, use <tt>dataUpdated</tt>. Use it by calling <tt>connectSource</tt>