← Development/Tutorials/Plasma4/Ruby/GettingStarted You do not have permission to edit this page, for the following reason: The action you have requested is limited to users in one of the groups: Users, Administrators, trusted, KDEDevelopers. You can view and copy the source of this page. Warning: This is a plain 'port' of the Getting Started article on Python and Plasma. I have changed the text where necessary for Ruby, and of course changed the example. Some things however might be incorrect. For the Python Tutorial see [http://techbase.kde.org/Development/Tutorials/Plasma/Python/GettingStarted here]. == Abstract == In this tutorial we'll cover setting up a very simple plasma applet in Ruby, and how to install it and run it, basically the edit, install, run and debug cycle. To follow this you will need to have KDE 4.2 or later installed, and also the ruby support for plasma and related dependencies. I'm going to assume that you are using a unix-style operating system such as Linux of *BSD and aren't adverse to the shell. == Project Structure == The first step for any software project is to set up your project's directory on disk. For this tutorial we are going to create a very simple "hello-ruby" applet. Create a directory on somewhere called <tt>hello-ruby</tt> which in turn contains a <tt>contents</tt> directory which then contains a <tt>code</tt> directory. This command below will do all this. <code bash> mkdir -p hello-ruby/contents/code </code> This creates a simple directory structure which also matches the package structure expect by the <tt>plasmapkg</tt> command. More on this later. == Metadata.desktop == In the <tt>hello-ruby</tt> directory create a file called <tt>metadata.desktop</tt> and open it in your text editor. Copy the following code into <tt>metadata.desktop</tt>. <code ini> [Desktop Entry] Encoding=UTF-8 Name=Hello Ruby Name[nl]=Hallo Ruby Type=Service ServiceTypes=Plasma/Applet Icon=chronometer X-Plasma-API=ruby X-Plasma-MainScript=code/main.rb X-KDE-PluginInfo-Author=Simon Edwards X-KDE-PluginInfo-Emailemail@example.com X-KDE-PluginInfo-Name=hello-ruby X-KDE-PluginInfo-Version=1.0 X-KDE-PluginInfo-Website=http://plasma.kde.org/ X-KDE- PluginInfo-Category=Examples X-KDE- PluginInfo-Depends= X-KDE- PluginInfo-Depends=GPL X-KDE- PluginInfo-EnabledByDefault=true </code> This <tt>metadata.desktop</tt> file list important information needed by Plasma to load the applet, and also information about what the applet is and who created it. The <tt>Name</tt> field lists the name of the applet. This field can also be listed multiple times as different translations. Here I've just given a Dutch translation of the name. The <tt>[nl]</tt> indicates the language of the field. The <tt>Type</tt> and <tt>ServiceType</tt> fields identify what kind of thing this desktop file is describing. Here we say that we have a plasma applet. The <tt>Icon</tt> field gives the name of the icon to associate with this applet. The icon is typically shown in things such as the "Add widget" dialog in Plasma. The <tt>X-Plasma-API</tt> and <tt>X-Plasma-MainScript</tt> fields are used specifically by Plasma to find the correct script-engine to use when loading and running the applet. Most of the <tt>X-KDE-PluginInfo-*</tt> fields give extra information about who created the applet. <tt>X-KDE-PluginInfo-Category</tt> lists a category which this applet belongs to. http://techbase.kde.org/Projects/Plasma/PIG has a list of acceptable category names. == Main script == Create a file in the <tt>contents/code</tt> directory called <tt>main.rb</tt>, open it up in your text editor and put this code in it and save it. <code ruby> # <Copyright and license information goes here.> require 'plasma_applet' module RubyStart class Main < PlasmaScripting::Applet def initialize parent super parent end def init self.has_configuration_interface = false resize 125, 125 self.aspect_ratio_mode = Plasma::Square end def paintInterface(painter, option, rect) painter.save painter.pen = Qt::white painter.draw_text rect, Qt::AlignVCenter | Qt::AlignHCenter, "Hello Ruby!" painter.restore end end end </code> This is basically the simplest applet which actually does something. The code starts out with the usual copyright notice and license information which I've actually left out for now. Next up is the loading of Ruby support in Plasma. Only loading <tt>plasma_applet</tt> is enough as it will load the rest of the Qt and KDE Ruby bindings. In order to create applets which can be packaged and delivered to users across the network via KDE's Get Hot New Stuff (GHNS) framework, we need to use the <tt>PlasmaScripting::Applet</tt> class as a base class for our applet. In our main class the constructor method (<tt>initialize</tt>) is almost empty and only forwards the call to the superclass. It's recommended to put most of the initialisation code in the <tt>init</tt> method. After Plasma has constructed and initialised the applet, Plasma will call the <tt>init</tt> method on the applet to let it continue setting itself up. Our <tt>init</tt> method is rather short. We just tell Plasma that we don't have a configuration dialog and we set up the initial size of the applet. The <tt>paintInterface</tt> method is where we draw our "Hello Ruby" message. First we save the state / settings of the given <tt>QPainter</tt> object by calling <tt>save</tt>. Then we set the color to white and use <tt>drawText</tt> to draw our message. Finally we call <tt>restore</tt> which resets the <tt>QPainter</tt> settings back to how it was when <tt>paintInterface</tt> was called. == Packaging, installing & running == Plasma applets can be packaged in zip files and installed using the <tt>plasmapkg</tt> command line tool. The directory structure which we have used for our project matches that need in the zip file. All we have to do is zip it update. Run the following command from inside the hello-ruby directory. <code bash> zip -r ../hello-ruby.zip . </code> This will create the hello-ruby.zip file in the directory just above the hello-ruby directory. Go to this directory in the shell and run this <tt>plasmapkg</tt> command to install our little hello-ruby applet. <code bash> plasmapkg -i hello-ruby.zip </code> This installs the applet into your home directory. Now we can run it. When developing applets it is more convenient to use the <tt>plasmoidviewer</tt>. This is a little utility which displays an applet in a window instead of you having to use your desktop. This command below will run our applet. <code bash> plasmoidviewer hello-ruby </code> You should now be able to see the fruits of your labor. To uninstall our applet we use <tt>plasmapkg</tt> again with its -r option. <code bash> plasmapkg -r hello-ruby </code> == Conclusion == This tutorial covers very basics of developing Plasma applets using Ruby. Most of the material discussed here is boring but important "boilerplate" stuff which stays mostly the same between every applet project. In future tutorials we can move on to move exciting things than just displaying a single line of static text. In the next tutorial we explain how to use Plasma's specialized widgets in your applet instead of manually implementing the <tt>paintInterface</tt> method. Templates used on this page: Template:Archived (view source) Template:Box (view source) Template:Warning (view source) Return to Development/Tutorials/Plasma4/Ruby/GettingStarted. Retrieved from "https://techbase.kde.org/Development/Tutorials/Plasma4/Ruby/GettingStarted"