Development/Tutorials/Plasma4/RubyApplet: Difference between revisions

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    This tutorial shows how to create your own Plasmoids using the Ruby scripting language.
     
     
    Warning: This tutorial is outdated. It doesn't work on KDE 4.2. This article is being kept for future translation to the current way of developing a Ruby Plasma applet. If you're looking for a tutorial on how to write a Plasma applet in Ruby on KDE 4.2 and later, have a look at the [[Development/Tutorials/Plasma/Ruby/GettingStarted|Getting Started]] tutorial.
     
    ==Abstract==
     
    This tutorial shows how to create your own Plasma Widget/Applet/Plasmoid using the Ruby scripting language.  
     
    See also:
    * [http://www.kdedevelopers.org/node/3560 Writing Plasma Applets in C# and Ruby]
    * [http://websvn.kde.org/trunk/KDE/kdebindings/ruby/plasma/examples/ Ruby and Plasma examples]
    * [[Development/Tutorials/Qt4_Ruby_Tutorial|Qt4 Ruby Tutorial]]
    * [[Development/Tutorials/Plasma|Plasma Tutorials]]


    ==The desktop file==
    ==The desktop file==
    Line 5: Line 17:
    The desktop file is the entry-point to our applet. It does define what the applet is for and how it should be loaded and handled by plasma.
    The desktop file is the entry-point to our applet. It does define what the applet is for and how it should be loaded and handled by plasma.


    [[http://websvn.kde.org/trunk/KDE/kdebindings/ruby/plasma/examples/applets/webapplet/plasma-ruby-applet-web.desktop?view=markup plasma-ruby-applet-web.desktop]]
    For our webbrowser applet we use the [http://websvn.kde.org/trunk/KDE/kdebindings/ruby/plasma/examples/applets/webapplet/plasma-ruby-applet-web.desktop?view=markup plasma-ruby-applet-web.desktop] desktop file which looks like;


    <code>
    <syntaxhighlight lang="ini">
    [Desktop Entry]
    [Desktop Entry]
    Name=Ruby Web Browser
    Name=Ruby Web Browser
    Line 19: Line 31:
    X-KDE-PluginInfo-Name=plasma-ruby-web-applet
    X-KDE-PluginInfo-Name=plasma-ruby-web-applet


    X-KDE-PluginInfo-Version=pre0.1
    X-KDE-PluginInfo-Version=0.1
    X-KDE-PluginInfo-Category=Web
    X-KDE-PluginInfo-Category=Web
    X-KDE-PluginInfo-Depends=QtRuby
    X-KDE-PluginInfo-Depends=QtRuby
    X-KDE-PluginInfo-License=GPL
    X-KDE-PluginInfo-License=GPL
    X-KDE-PluginInfo-EnabledByDefault=true
    X-KDE-PluginInfo-EnabledByDefault=true
    </code>
    </syntaxhighlight>


    The important parts within those desktop service file are the referenced X-KDE-Library which will be loaded on request and is responsible for executing our with X-KDE-PluginKeyword defined Ruby scrip file. Our applet will be known by Plasma under the unique name "plasma-ruby-web-applet".
    The important parts within those desktop service file are the referenced X-KDE-Library which will be loaded on request and is responsible for executing our with X-KDE-PluginKeyword defined Ruby scrip file. Our applet will be known by Plasma under the unique name "plasma-ruby-web-applet".
    Line 30: Line 42:
    ==The Ruby Script==
    ==The Ruby Script==


    It follows the Ruby scripting code which does implement the whole functionality to display a webbrowser within the applet and to allow to browse around.
    It follows the Ruby scripting code which does implement the whole functionality to display a webbrowser within the applet and to browse around those content.


    [http://websvn.kde.org/trunk/KDE/kdebindings/ruby/plasma/examples/applets/webapplet/web_applet.rb?view=markup web_applet.rb]
    The [http://websvn.kde.org/trunk/KDE/kdebindings/ruby/plasma/examples/applets/webapplet/web_applet.rb?view=markup web_applet.rb] ruby script looks like;


    <code ruby>
    <syntaxhighlight lang="ruby">
    # import the plasma-applet functionality which we need to implement our own applet.
    # import the plasma-applet functionality which we need to
    # implement our own webbrowser applet.
    require 'plasma_applet'
    require 'plasma_applet'


    # we define an own module
    # We define an own module
    module PlasmaRubyWebApplet
    module PlasmaRubyWebApplet


       # the WebApplet class does implement the Plasma::Applet
       # The WebApplet class does implement a Plasma::Applet.
       class WebApplet < Plasma::Applet
       class WebApplet < Plasma::Applet


         # the both slots used by our applet.
         # The both slots used by our applet.
         slots 'load(QUrl)',
         slots 'load(QUrl)',
               'loadFinished(bool)'
               'loadFinished(bool)'


         # constructor.
         # Constructor for our WebApplet class.
         def initialize(parent, args)
         def initialize(parent, args)
           super
           super
         end
         end


         # on initialization this method will be called.
         # On initialization this method will be called by plasma. Here we
        # are able to do expensive initialization work to show something
        # within our applet.
         def init
         def init
          # Let's start with a nice default size.
           resize(600, 400)
           resize(600, 400)


           # create the Browser widget which will display the content.
           # Create the Browser widget which will display the content
          # of webpages.
           @page = Plasma::WebContent.new(self)
           @page = Plasma::WebContent.new(self)
           @page.page = Qt::WebPage.new(@page)
           @page.page = Qt::WebPage.new(@page)
    Line 64: Line 81:
             Qt::WebSettings::LinksIncludedInFocusChain, true)
             Qt::WebSettings::LinksIncludedInFocusChain, true)


          # Connect signals the webbrowser provides with own functions.
           connect(@page, SIGNAL('loadFinished(bool)'),
           connect(@page, SIGNAL('loadFinished(bool)'),
                   self, SLOT('loadFinished(bool)'))
                   self, SLOT('loadFinished(bool)'))
    Line 69: Line 87:
                   self, SLOT('load(QUrl)'))
                   self, SLOT('load(QUrl)'))


           # start browsing some webpage
           # Start browsing some webpage
           @page.url = Qt::Url.new("http://dot.kde.org/")
           @page.url = Qt::Url.new("http://dot.kde.org/")
         end
         end


         # this method will be called once the user clicks on a link. we
         # This method will be called once the user clicks on a link.
         # just load the defined url and display it.
         # We just load the defined URL-address and let the
        # webbrowser-page display the content.
         def load(url)
         def load(url)
           puts "Loading #{url.toString}"
           puts "Loading #{url.toString}"
    Line 80: Line 99:
         end
         end


         # this method will be called once loading a page finished.
         # This method will be called once loading a page finished.
         def loadFinished(success)
         def loadFinished(success)
           puts "page loaded #{@page.page.currentFrame.url.toString}"
           puts "page loaded #{@page.page.currentFrame.url.toString}"
         end
         end


         # this method will be called each time a constraint changed. the
         # This method will be called each time a constraint changed. the
         # for us most interesting constraints are;
         # for us most interesting constraints are;
         # * LocationConstraint if the location of the applet changed
         # * LocationConstraint if the location of the applet changed
    Line 94: Line 113:
         def constraintsEvent(constraints)
         def constraintsEvent(constraints)
           if constraints.to_i & Plasma::SizeConstraint.to_i
           if constraints.to_i & Plasma::SizeConstraint.to_i
            # if the size of the Applet changed, then resize also the
            # webbrowser.
             @page.resize(size())
             @page.resize(size())
           end
           end
    Line 100: Line 121:
       end
       end
    end
    end
    </code>
    </syntaxhighlight>


    ==Installing the applet==
    That was already all the code needed to implement our own webbrowser Applet using the Ruby language. The in this sample used [http://doc.trolltech.com/4.4/qtwebkit.html webbrowser] does provide additional functionality to use optional a full powered webbrowser or adopt it to your needings.


    To install the applet the [[http://websvn.kde.org/trunk/KDE/kdebindings/ruby/plasma/examples/applets/webapplet/CMakeLists.txt?view=markup CMakeLists.txt]] is used. It basicly does copy the both files above to the right locations
    ==Install and test the Applet==


    <code>
    To install the Applet the [http://websvn.kde.org/trunk/KDE/kdebindings/ruby/plasma/examples/applets/webapplet/CMakeLists.txt?view=markup CMakeLists.txt] is used. It basically does copy the both files above to the right locations. Translated to command-line arguments it would look like;
    cp plasma-ruby-applet-web.desktop `kde4-config --install services`
    cp web_applet.rb `kde4-config --install data`/plasma_ruby_web_applet/
    </code>


    what installs the both files for all users. If you like to have them accessible only from within one user, then just copy those both files to your $KDEHOME where the command "kde4-config --localprefix" should provide you a hint where that may be :)
    <syntaxhighlight lang="bash">
    sudo cp plasma-ruby-applet-web.desktop `kde4-config --install services`
    sudo mkdir `kde4-config --install data`/plasma_ruby_web_applet/
    sudo cp web_applet.rb `kde4-config --install data`/plasma_ruby_web_applet/
    </syntaxhighlight>


    To take a look at your applet or test it during the developing, you can fire up;
    what installs the both files to the global installation directory to make hem available for all users on your sysem. If you like to have them accessible only from within one user, then just copy those both files to the users $KDEHOME (the command "kde4-config --localprefix" should provide you a hint where that may be).


    <code>
    To take a look at your applet or test it during development, you can;
     
    <syntaxhighlight lang="bash">
    kbuildsycoca4
    kbuildsycoca4
    plasmoidviewer plasma-ruby-web-applet
    plasmoidviewer plasma-ruby-web-applet
    </code>
    </syntaxhighlight>
     
    where the kbuildsycoca4 does rebuild the desktop-cache to update changes done to the desktop file. The plasmoidviewer is a tool that allows you to start and view your applet outside of plasma.
    [[Media:Example.ogg]]


    where the kbuildsycoca4 does rebuild the desktop-cache to update changes done at the desktop file. The plasmoidviewer is a tool that allows you to start and view your applet outside of plasma.
    [[Category:Ruby]]

    Revision as of 23:27, 11 September 2014


    Warning: This tutorial is outdated. It doesn't work on KDE 4.2. This article is being kept for future translation to the current way of developing a Ruby Plasma applet. If you're looking for a tutorial on how to write a Plasma applet in Ruby on KDE 4.2 and later, have a look at the Getting Started tutorial.

    Abstract

    This tutorial shows how to create your own Plasma Widget/Applet/Plasmoid using the Ruby scripting language.

    See also:

    The desktop file

    The desktop file is the entry-point to our applet. It does define what the applet is for and how it should be loaded and handled by plasma.

    For our webbrowser applet we use the plasma-ruby-applet-web.desktop desktop file which looks like;

    [Desktop Entry]
    Name=Ruby Web Browser
    Icon=internet-web-browser
    
    Type=Service
    ServiceTypes=Plasma/Applet
    
    X-KDE-Library=krubypluginfactory
    X-KDE-PluginKeyword=plasma_ruby_web_applet/web_applet.rb
    X-KDE-PluginInfo-Name=plasma-ruby-web-applet
    
    X-KDE-PluginInfo-Version=0.1
    X-KDE-PluginInfo-Category=Web
    X-KDE-PluginInfo-Depends=QtRuby
    X-KDE-PluginInfo-License=GPL
    X-KDE-PluginInfo-EnabledByDefault=true
    

    The important parts within those desktop service file are the referenced X-KDE-Library which will be loaded on request and is responsible for executing our with X-KDE-PluginKeyword defined Ruby scrip file. Our applet will be known by Plasma under the unique name "plasma-ruby-web-applet".

    The Ruby Script

    It follows the Ruby scripting code which does implement the whole functionality to display a webbrowser within the applet and to browse around those content.

    The web_applet.rb ruby script looks like;

    # import the plasma-applet functionality which we need to
    # implement our own webbrowser applet.
    require 'plasma_applet'
    
    # We define an own module
    module PlasmaRubyWebApplet
    
      # The WebApplet class does implement a Plasma::Applet.
      class WebApplet < Plasma::Applet
    
        # The both slots used by our applet.
        slots 'load(QUrl)',
              'loadFinished(bool)'
    
        # Constructor for our WebApplet class.
        def initialize(parent, args)
          super
        end
    
        # On initialization this method will be called by plasma. Here we
        # are able to do expensive initialization work to show something
        # within our applet.
        def init
          # Let's start with a nice default size.
          resize(600, 400)
    
          # Create the Browser widget which will display the content
          # of webpages.
          @page = Plasma::WebContent.new(self)
          @page.page = Qt::WebPage.new(@page)
          @page.page.linkDelegationPolicy = Qt::WebPage::DelegateAllLinks
          @page.page.settings.setAttribute(
            Qt::WebSettings::LinksIncludedInFocusChain, true)
    
          # Connect signals the webbrowser provides with own functions.
          connect(@page, SIGNAL('loadFinished(bool)'),
                  self, SLOT('loadFinished(bool)'))
          connect(@page.page, SIGNAL('linkClicked(QUrl)'),
                  self, SLOT('load(QUrl)'))
    
          # Start browsing some webpage
          @page.url = Qt::Url.new("http://dot.kde.org/")
        end
    
        # This method will be called once the user clicks on a link.
        # We just load the defined URL-address and let the
        # webbrowser-page display the content.
        def load(url)
          puts "Loading #{url.toString}"
          @page.url = url
        end
    
        # This method will be called once loading a page finished.
        def loadFinished(success)
          puts "page loaded #{@page.page.currentFrame.url.toString}"
        end
    
        # This method will be called each time a constraint changed. the
        # for us most interesting constraints are;
        # * LocationConstraint if the location of the applet changed
        # * ScreenConstraint if the screen on which the applet is located
        #   on changed
        # * SizeConstraint if the size of the applet changed
        # * ImmutableConstraint if the applet got locked/unlocked
        def constraintsEvent(constraints)
          if constraints.to_i & Plasma::SizeConstraint.to_i
            # if the size of the Applet changed, then resize also the
            # webbrowser.
            @page.resize(size())
          end
        end
    
      end
    end
    

    That was already all the code needed to implement our own webbrowser Applet using the Ruby language. The in this sample used webbrowser does provide additional functionality to use optional a full powered webbrowser or adopt it to your needings.

    Install and test the Applet

    To install the Applet the CMakeLists.txt is used. It basically does copy the both files above to the right locations. Translated to command-line arguments it would look like;

    sudo cp plasma-ruby-applet-web.desktop `kde4-config --install services`
    sudo mkdir `kde4-config --install data`/plasma_ruby_web_applet/
    sudo cp web_applet.rb `kde4-config --install data`/plasma_ruby_web_applet/
    

    what installs the both files to the global installation directory to make hem available for all users on your sysem. If you like to have them accessible only from within one user, then just copy those both files to the users $KDEHOME (the command "kde4-config --localprefix" should provide you a hint where that may be).

    To take a look at your applet or test it during development, you can;

    kbuildsycoca4
    plasmoidviewer plasma-ruby-web-applet
    

    where the kbuildsycoca4 does rebuild the desktop-cache to update changes done to the desktop file. The plasmoidviewer is a tool that allows you to start and view your applet outside of plasma. Media:Example.ogg