< Development‎ | Tutorials‎ | Plasma4
Revision as of 12:08, 11 March 2011 by Mart (talk | contribs)



Writing a plasma applet in QML is very easy, in fact, with KDE 4.6 and Qt 4.7 it just works.

Package Structure

You create a .desktop file and the .qml file. They have to be in the usual plasma package structure.

plasmoid-qml/metadata.desktop plasmoid-qml/contents/ui/main.qml


[Desktop Entry] Name=Hello QML Comment=A hello world widget in QML Icon=chronometer

X-Plasma-API=declarativeappletscript X-Plasma-MainScript=ui/main.qml X-Plasma-DefaultSize=200,100

X-KDE-PluginInfo-Author=Frederik Gladhorn [email protected] X-KDE-PluginInfo-Website=http://plasma.kde.org/ X-KDE-PluginInfo-Category=Examples X-KDE-PluginInfo-Name=org.kde.hello-qml X-KDE-PluginInfo-Version=0.0

X-KDE-PluginInfo-Depends= X-KDE-PluginInfo-License=GPL X-KDE-PluginInfo-EnabledByDefault=true X-KDE-ServiceTypes=Plasma/Applet Type=Service


import Qt 4.7

Text {

   text: "Hello world!";



You can install your plasmoid: plasmapkg --install plasmoid-qml


You can run it in plasmoidviewer as usual: plasmoidviewer plasmoid-qml


It's possible to use Plasma specific imports in qml files loaded by qmlviewer:

qmlviewer -I /usr/lib/kde4/imports/ plasmoid-qml/contents/qml/main.qml

Where the -I is the path to the plasma plugin for qml. Try to look for the path of /usr/lib/kde4/imports/org/kde/plasma/graphicswidgets/libgraphicswidgetsbindingsplugin.so and use everything up to org of that path.

Hovewer it's strongly discouraged to use qmlviewer to develop plasmoids, because some features won't be available there:

  • localization with i18n()
  • access to the global plasmoid object
  • device specific qml files imported with plasmapackage:// urls
  • bindings for qicons, KJobs, services and KConfig

Features only available in Plasma widgets

In order to have a better integration with the KDE platform and to reach an higher degree of expressivity, the stock features of QML have been expanded with the following features, that strictly follow the Plasmoid JavaScript API:

Plasmoid object

Every QML plasmoid will have an object called plasmoid, that will give access to the configuration, the formfactor, immutability and so on. It offers the same api as the object with the same name in the Javascript API.


It's possible to localize strings with the usual i18n(), i18nc(), i18np() global functions

Extra types

Some extra types are available from withing JavaScript, namely

  • KConfigGroup: it's an object with its cnfig keys readable and writable as properties
  • QIcon: can be constructed with QIcon("fdo name") such as QIcon("konqueror")
  • KJob
  • Plasma Service api

Plasma specific imports

To use some Plasma specific features is necessary to use some particular QML imports.

Plasma Core

org.kde.plasma.core This is the import that lets you access to the most important Plasma Core features.


Used to connect to a dataengine


Attaches to a DataSource, makes possible to use a dataengine as a model for a QML ListView, GridView, PathView and so on


Loads a Plasma Svg, it's not the visual item


Visual item that paints a Svg


Loads a Plasma FrameSvg, it's not the visual item.


Visual item that displays a Plasma FrameSvg

Extra Qt features


  • QPixmapItem
  • QImageItem
  • QIconItem

Plasma Widgets in QML

To use plasma widgets, you simply add an import line for them. All properties, signals and slots from ordinary Plasma widgets are available there. Those widgets are provided as a transition tool, intended to be replaced by the Plasma version of QtComponents.

import Qt 4.7 import org.kde.plasma.graphicswidgets 0.1 as PlasmaWidgets

Item {

   width: 64
   height: 64
   PlasmaWidgets.IconWidget {
       id: icon
       Component.onCompleted: setIcon("flag-red")
       anchors.centerIn: parent


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