Languages/Ruby: Difference between revisions

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{{Archived}}
{{Note|The information below applies to older versions of Qt only. There are currently no Ruby bindings for Qt 5 and KDE Frameworks 5 available.}}
{{Warning|Some important links are non-functional, specially the official Korundum page. Until we solve this problem you can find the source code at [https://projects.kde.org/projects/kde/kdebindings/ruby kdebindings project page]}}
[[Image:ruby.png]]
[[Image:ruby.png]]


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[http://rubyforge.org/projects/korundum/ Korundum/QtRuby - Ruby-KDE/Qt bindings]
[http://rubyforge.org/projects/korundum/ Korundum/QtRuby - Ruby-KDE/Qt bindings]


NEW - The book [http://www.pragmaticprogrammer.com/titles/ctrubyqt/ Rapid GUI Development with QtRuby] is now available.
The book [http://www.pragmaticprogrammer.com/titles/ctrubyqt/ Rapid GUI Development with QtRuby] (for Qt version 3.x) is available.


Being [http://developer.kde.org/language-bindings/smoke/index.html Smoke-based] bindings means that they offer full access to most KDE 3.x and Qt 3.x classes.
Being [http://developer.kde.org/language-bindings/smoke/index.html Smoke-based] bindings means that they offer full access to most KDE 4.x and Qt 4.x classes.


= QtRuby =
= QtRuby =
Hello world example:
Hello world example:
<code>
<syntaxhighlight lang="ruby">
#!/usr/bin/ruby -w
#!/usr/bin/ruby -w
require 'Qt'
require 'Qt4'
a = Qt::Application.new(ARGV)
a = Qt::Application.new(ARGV)
hello = Qt::PushButton.new("Hello World!", nil)
hello = Qt::PushButton.new("Hello World!")
hello.resize(100, 30)
hello.resize(100, 30)
a.mainWidget = hello
hello.show
hello.show()
a.exec
a.exec()
</syntaxhighlight>
</code>
 
Hello Qt example in a more 'Rubyish' way:
 
<syntaxhighlight lang="ruby">
require 'Qt4'
 
Qt::Application.new(ARGV) do
    Qt::Widget.new do
 
        self.window_title = 'Hello QtRuby v1.0'
        resize(200, 100)
   
        button = Qt::PushButton.new('Quit') do
            connect(SIGNAL :clicked) { Qt::Application.instance.quit }
        end
 
        label = Qt::Label.new('<big>Hello Qt in the Ruby way!</big>')
       
        self.layout = Qt::VBoxLayout.new do
            add_widget(label, 0, Qt::AlignCenter)
            add_widget(button, 0, Qt::AlignRight)
        end
       
        show
    end
   
    exec
end
</syntaxhighlight>
 
= Current api coverage overview =
= Current api coverage overview =


Line 34: Line 70:


Any underscores in method names are removed, and the following character is capitalised. For example, you can use either of these two forms to call the same method:
Any underscores in method names are removed, and the following character is capitalised. For example, you can use either of these two forms to call the same method:
      create_standard_status_bar_action()
 
      createStandardStatusBarAction()
<syntaxhighlight lang="ruby">
create_standard_status_bar_action()
createStandardStatusBarAction()
</syntaxhighlight>


==Operator overloading==
==Operator overloading==
The full range of Qt operator methods is available, for example:
The full range of Qt operator methods is available, for example:


      p1 = Qt::Point.new(5,5)  => (5, 5)
<syntaxhighlight lang="ruby">
      p2 = Qt::Point.new(20,20) => (20, 20)
p1 = Qt::Point.new(5,5)  => (5, 5)
      p1 + p2                  => (25, 25)
p2 = Qt::Point.new(20,20) => (20, 20)
p1 + p2                  => (25, 25)
</syntaxhighlight>


==Declare signals and slots==
==Declare signals and slots==
Signals and slots are declared as list of strings like this:


Signals and slots are declared as list of strings like this:
<syntaxhighlight lang="ruby">
slots 'setColor(QColor)', 'slotLoad(const QString&)'..
signals 'clicked()'..
</syntaxhighlight>
 
For slots and signals without arguments you can use Ruby symbols:


      slots 'setColor(QColor)', 'slotLoad(const QString&)'..
<syntaxhighlight lang="ruby">
      signals 'clicked()'..
slots :slotLoad
signals :clicked
</syntaxhighlight>


Currently C++ type signatures must be used, a future version of QtRuby will allow ruby type signatures instead.
Currently C++ type signatures must be used, a future version of QtRuby will allow ruby type signatures instead. (see the section on emitting Ruby Classes)


Connect slots and signals like this:
Connect slots and signals like this:


      Qt::Object.connect( @colormenu, SIGNAL( "activated( int )" ),
<syntaxhighlight lang="ruby">
                        self, SLOT( "slotColorMenu( int )" ) )
Qt::Object.connect( @colormenu, SIGNAL( "activated(int)" ),
                  self, SLOT( "slotColorMenu(int)" ) )
</syntaxhighlight>
 
There is also two another possibilities:
 
<syntaxhighlight lang="ruby">
connect(:mysig, mytarget, :mymethod))
connect(SIGNAL('mysignal(int)'), mytarget, :mymethod))
</syntaxhighlight>
 
Or you can connect signal to a block:
 
<syntaxhighlight lang="ruby">
quit_button.connect(SIGNAL :clicked) { $qApp.quit }
</syntaxhighlight>


And emit signals like this:
And emit signals like this:


      emit colorChanged( black )
<syntaxhighlight lang="ruby">
emit colorChanged( black )
</syntaxhighlight>
 
==Emitting Ruby Classes==
Ruby classes can be emitted by embedding them inside a QVariant, and emitting the QVariant.
 
The following code provides a method called to_variant that can be used to easily convert objects to Variants
<syntaxhighlight lang="ruby">
class Qt::RubyVariant < Qt::Variant
    def initialize(value)
        super()
        @value = value
    end
 
    attr_accessor :value
end
 
class Object
    def to_variant
        Qt::RubyVariant.new self
    end
end
</syntaxhighlight>
 
Note: as of KDE 4.5 you can simply use
<syntaxhighlight lang="ruby">
variant = Qt::Variant.fromValue(my_ruby_object)
</syntaxhighlight>
to create a QVariant that contains your ruby object. To get it back, you just call Qt::Variant#value as usual.
 
This can be used as follows
<syntaxhighlight lang="ruby">
class MyObject < Qt::Object
    signals "mySignal(QVariant)"
    def doEmit
        # since KDE 4.5:
        # emit mySignal(Qt::Variant.fromValue(ruby_object))
        emit mySignal(ruby_object.to_variant)
    end
 
    slots "mySlot(QVariant)"
    def mySlot(variant)
        ruby_object = variant.value
    end
end
</syntaxhighlight>
 
=== Alternate way to emit Ruby Classes ===
You can also try to emit a ruby class by emitting it's object_id (either as an Integer or a QVariant), and use ObjectSpace._id2ref to get the object back.
 
<syntaxhighlight lang="ruby">
class Object
    def to_variant
        Qt::Variant.new object_id
    end
end
 
class Qt::Variant
    def to_object
        ObjectSpace._id2ref to_int
    end
end
</syntaxhighlight>


==Constructors==
==Constructors==
You can call constructors in the conventional style:
You can call constructors in the conventional style:


      quit = Qt::PushButton.new("Quit", self, "quit")
<syntaxhighlight lang="ruby">
quit = Qt::PushButton.new("Quit", self, "quit")
</syntaxhighlight>


Or you can pass a block if you prefer:
Or you can pass a block if you prefer:


      w = MyWidget.new { setCaption("foobar") }
<syntaxhighlight lang="ruby">
w = MyWidget.new { setCaption("foobar") }
</syntaxhighlight>


The block will be called in the context of the newly created instance.
The block will be called in the context of the newly created instance.
Line 77: Line 206:
Ordinary arguments can be provided as well as a block at the end:
Ordinary arguments can be provided as well as a block at the end:


      w = MyWidget.new(nil) { setCaption("foobar") }
<syntaxhighlight lang="ruby">
w = MyWidget.new(nil) { setCaption("foobar") }
</syntaxhighlight>


They are run in the context of the new instance.
They are run in the context of the new instance.
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And there's more! You can also pass an arg to the block, and it will be run in the context of the arg:
And there's more! You can also pass an arg to the block, and it will be run in the context of the arg:


      w = MyWidget.new { |theWidget| theWidget.setCaption "foobar" }
<syntaxhighlight lang="ruby">
w = MyWidget.new { |theWidget| theWidget.setCaption "foobar" }
</syntaxhighlight>


==Garbage Collection==
==Garbage Collection==
When a ruby instance is garbage collected, the underlying C++ instance will only be deleted if it isn't 'owned' by a parent object. Normally this will 'just work', but there are occasions when you need to delete the C++ ahead of garbage collection, and whether or not it has a parent. Use the dispose(), isDisposed() and disposed? methods like this:
When a ruby instance is garbage collected, the underlying C++ instance will only be deleted if it isn't 'owned' by a parent object. Normally this will 'just work', but there are occasions when you need to delete the C++ ahead of garbage collection, and whether or not it has a parent. Use the dispose(), isDisposed() and disposed? methods like this:


      item2.dispose
<syntaxhighlight lang="ruby">
      if item2.disposed?
item2.dispose
      puts "item2 is disposed"
if item2.disposed?
      end
puts "item2 is disposed"
end
</syntaxhighlight>


==C++ 'int*' and 'int&' argument types==
==C++ 'int*' and 'int&' argument types==
Ruby passes numeric values by value, and so they can't be changed when passed to a method. The Qt::Integer class provides a mutable numeric type which does get updated when passed as an argument. For example, this C++ method 'findByFileContent()':
Ruby passes numeric values by value, and so they can't be changed when passed to a method. The Qt::Integer class provides a mutable numeric type which does get updated when passed as an argument. For example, this C++ method 'findByFileContent()':


      # static Ptr findByFileContent( const QString &fileName,  
<syntaxhighlight lang="ruby">
      #                              int *accuracy=0 );
# static Ptr findByFileContent( const QString &fileName,  
#                              int *accuracy=0 );
      acc = Qt::Integer.new(0)
      fc = KDE::MimeType.findByFileContent("mimetype.rb", acc)
   
   
acc = Qt::Integer.new(0)
fc = KDE::MimeType.findByFileContent("mimetype.rb", acc)
</syntaxhighlight>


It supports the arithmetic operators, and so expressions such as 'acc + 3' will work.
It supports the arithmetic operators, and so expressions such as 'acc + 3' will work.


==C++ 'bool*' and 'bool&' argument types==
==C++ 'bool*' and 'bool&' argument types==
There is a similar problem for bool arg types, and the mutable Qt::Boolean class can be used like this:
There is a similar problem for bool arg types, and the mutable Qt::Boolean class can be used like this:


      # QFont getFont(bool * ok, const QFont&initial,  
<syntaxhighlight lang="ruby">
      #              QWidget* parent = 0, const char *name = 0);
# QFont getFont(bool * ok, const QFont&initial,  
#              QWidget* parent = 0, const char *name = 0);
 
 
      ok = Qt::Boolean.new
ok = Qt::Boolean.new
      font = Qt::FontDialog.getFont(ok,  
font = Qt::FontDialog.getFont(ok,  
                          Qt::Font.new("Helvetica [Cronyx]", 10),  
                    Qt::Font.new("Helvetica [Cronyx]", 10),  
                          self)
                    self)
      if !ok.nil?  
if !ok.nil?  
      # font is set to the font the user selected
# font is set to the font the user selected
      else  
else  
      # the user canceled the dialog
# the user canceled the dialog
      end
end
</syntaxhighlight>


Use 'nil?' to test the value returned in the Boolean
Use 'nil?' to test the value returned in the Boolean
==C++ (const )(unsigned )char* argument types==
In some cases Qt/KDE object "takes ownership" over Ruby String passed as char* argument type. Programmer needs to make sure that Ruby String is not being garbage collected or changed for the time it's being used by Qt/KDE object. It is also quite possible that Qt/KDE object will change and eventually free it(memory used internally by Ruby String to store its data). Be very careful when you call this kind of methods and make sure that there is no overloaded version witch accepts QString or QByteArray first!
==C++ unsigned char* functions==
Very few functions (as QImage::bits()) return a uchar* to directly manipulate data. These functions are not supported in Ruby and will throw an ArgumentError. More information on the [http://lists.kde.org/?l=kde-bindings&m=122899325331866&w=2 mail list].


==Debugging==
==Debugging==
If a method call can't be matched in the Smoke library giving a 'method_missing' error, first check that you are passing correct class instance that is properly initialized (with super method called in constructors of custom Qt classes descendants). You can also turn on debugging to trace the matching process:


If a method call can't be matched in the Smoke library giving a 'method_missing' error, you can turn on debugging to trace the matching process:
<syntaxhighlight lang="ruby">
 
a = Qt::Application.new(ARGV)
      a = Qt::Application.new(ARGV)
Qt.debug_level = Qt::DebugLevel::High
      Qt.debug_level = Qt::DebugLevel::High
a.loadLibrary("foo")  # Non existent method
      a.loadLibrary("foo")  # Non existent method
</syntaxhighlight>


Will give the following output:
Will give the following output:
Line 143: Line 286:
           static QWidget* QApplication::widgetAt(int, int, bool)
           static QWidget* QApplication::widgetAt(int, int, bool)
  ...
  ...
Here, the list of candidate methods 'methodIds' is empty
Here, the list of candidate methods 'methodIds' is empty


Line 149: Line 293:
You can trace virtual method callbacks:
You can trace virtual method callbacks:


      Qt::Internal::setDebug(Qt::QtDebugChannel::QTDB_VIRTUAL)
<syntaxhighlight lang="ruby">
Qt::Internal::setDebug(Qt::QtDebugChannel::QTDB_VIRTUAL)
</syntaxhighlight>


Or trace QtRuby garbage collection:
Or trace QtRuby garbage collection:


      Qt::Internal::setDebug(Qt::QtDebugChannel::QTDB_GC)
<syntaxhighlight lang="ruby">
Qt::Internal::setDebug(Qt::QtDebugChannel::QTDB_GC)
</syntaxhighlight>


==String i18n==
==String i18n==
Line 162: Line 310:


==Qt Designer==
==Qt Designer==
A 'rbuic4' tool is included in qtruby/tools/rbuic to compile .ui files into ruby code. As described above, Qt Designer uses UTF-8. In addition to the options in the original uic C++ utility an '-x' flag has been added. This will generate a top level stub in the code:


A 'rbuic' tool is included in qtruby/rubylib/designer/rbuic to compile .ui files into ruby code. As described above, Qt Designer uses UTF-8. In addition to the options in the original uic C++ utility an '-x' flag has been added. This will generate a top level stub in the code:
<syntaxhighlight lang="bash">
 
$ rbuic mainform.ui -x -o mainform.rb
      $ rbuic mainform.ui -x -o mainform.rb
</syntaxhighlight>


Will add this to the end of the generated code:
Will add this to the end of the generated code:


      if $0 == __FILE__
<syntaxhighlight lang="ruby">
          a = Qt::Application.new(ARGV)
if $0 == __FILE__
          w = MainForm.new
    a = Qt::Application.new(ARGV)
          a.setMainWidget(w)
    w = MainForm.new
          w.show
    w.show
          a.exec
    a.exec
      end
end
</syntaxhighlight>


Then you can test the example code straight away:
Then you can test the example code straight away:
Line 181: Line 331:
       $ ruby mainform.rb
       $ ruby mainform.rb


Use the '-kde' option to require the 'Korundum' extension rather than the 'Qt' one. If the '-x' option is used in conjunction, it generates a KDE top level. For example:
Use the '-kde' option to require the 'korundum4' extension rather than the 'Qt4' one. If the '-x' option is used in conjunction, it generates a KDE top level. For example:


      $ rbuic -x -kde knotifywidgetbase.ui -o knotifywidgetbase.rb
<syntaxhighlight lang="bash">
$ rbuic4 -x -kde knotifywidgetbase.ui -o knotifywidgetbase.rb
</syntaxhighlight>


Will generate this top level code:
Will generate this top level code:


      if $0 == __FILE__
<syntaxhighlight lang="ruby">
      about = KDE::AboutData.new("knotifywidgetbase",  
if $0 == __FILE__
                          "KNotifyWidgetBase", "0.1")
    about = KDE::AboutData.new("knotifywidgetbase",  
      KDE::CmdLineArgs.init(ARGV, about)
                      "KNotifyWidgetBase", "0.1")
        a = KDE::Application.new()
    KDE::CmdLineArgs.init(ARGV, about)
    w = KNotifyWidgetBase.new
    a = KDE::Application.new()
    a.setMainWidget(w)
    w = KNotifyWidgetBase.new
    w.show
    w.show
    a.exec
    a.exec
      end
end
</syntaxhighlight>
 
==Loading .ui files at runtime with Qt::UiLoader==
 
Let's say you created a file in your project directory called 'gui.ui' using Qt Designer ('/usr/bin/designer', comes with Qt. At least on Arch).
You can load it like so:
 
<syntaxhighlight lang="ruby">
require 'Qt4'
require 'qtuitools'


==Loading .ui files at runtime with QUI::WidgetFactory==
class MyApp < Qt::Application
    def initialize
        super ARGV


You can load a Qt Designer .ui file at runtime with the 'qui' extension, for example:
        # 'gui.ui' was created with qt designer ('designer' on arch linux)
        file = Qt::File.new 'gui.ui' do
            open Qt::File::ReadOnly
        end
       
        window = Qt::UiLoader.new.load file


      require 'Qt'
        file.close
      require 'qui'
      a = Qt::Application.new(ARGV)
      if ARGV.length == 0
        exit
      end
      if ARGV.length == 2
        QUI::WidgetFactory.loadImages ARGV[0]
        w = QUI::WidgetFactory.create ARGV[1]
        if w.nil?
          exit
        end
        w.show()
        a.connect(a, SIGNAL('lastWindowClosed()'), a, SLOT('quit()'))
        a.exec()
      end


==QtRuby shell==
        if window.nil?
            print "Error. Window is nil.\n"
            exit
        end
        window.show
    end
end


You can use the QtRuby shell in bin/rbqtsh to create widgets interactively from the command line.
a = MyApp.new
a.exec
</syntaxhighlight>


==API reference==
==API reference==


Use the bin/rbqtapish tool to discover which methods are available in the QtRuby api. This command:
Use the bin/rbqtapi tool to discover which methods are available in the QtRuby api. This command:


  $ rbqtapish Qt::TextEdit
<syntaxhighlight lang="bash">
$ rbqtapi Qt::TextEdit
</syntaxhighlight>


Will list all the methods in the Qt::TextEdit class
Will list all the methods in the Qt::TextEdit class


  $ rbqtapi -rsetCaption  
<syntaxhighlight lang="bash">
$ rbqtapi -rsetCaption  
</syntaxhighlight>


Lists all methods whose names contain the string 'setCaption'
Lists all methods whose names contain the string 'setCaption'
Line 239: Line 403:
==Example programs==
==Example programs==


The best way to start programming QtRuby is to look at some existing code and start messing with it.. The are various samples under qtruby/rubylib/examples and korundum/rubylib/examples.
The best way to start programming QtRuby is to look at some existing code and start messing with it.. The are various samples under qtrubyexamples and korundum/examples.


=KDE Specific Infomation=
==Writing Unit Tests==
Using Ruby allows you the power to leverage testing frameworks such as RSpec in order to unit and integration test your classes.


Instead of <code>require 'Qt'</code>, use <code>require 'Korundum'</code> for KDE programs.
Most classes such as Models can be easily tested via the APIs they expose. Below is a small extract with some interesting tests from the mingle_mover project (http://github.com/gja/mingle_mover). The class being tested is a TableModel


The KDE K* classes such as KApplication are renamed as KDE::Application. The other KDE classes are in the KParts::, KIO:: or DOM:: namespaces, with the same names as their C++ counterparts.
Note how we create a stub to pass to QAbstractTableModel::data, which accepts a QModelIndex as an argument.


Use the 'rbkdeapi' script to introspect the Korundum api from the command line. For example:
<syntaxhighlight lang="ruby">
describe CardModel do
    it "Should Implement QAbstractTableModel" do
        CardModel.ancestors.should include Qt::AbstractTableModel
    end


      $ rbkdeapi KDE::Action
    it "Should Not Be Editable" do
        @model.data(mock_index(1,2), Qt::EditRole).should_not be_valid
        @model.headerData(nil, nil, Qt::EditRole).should_not be_valid
       
        flags = @model.flags(nil)
        flags.should have_flag Qt::ItemIsEnabled
        flags.should have_flag Qt::ItemIsSelectable
        flags.should_not have_flag Qt::ItemIsEditable
    end


Will list all the methods in the KDE::Action class. There are currently (as at KDE 3.3 beta 2) 977 classes/30841 methods in the Smoke library runtime, so the coverage of the Qt/KDE api is pretty complete.
    it "Should not return any vertical headers" do
        @model.headerData(1, Qt::Vertical).should_not be_valid
    end


=DCOP Support=
    it "Should color a row according to the status" do
        @model.data(mock_index(1,2), Qt::ForegroundRole).value.color.should == Qt::Color.new(Qt::red)
        @model.data(mock_index(0,2), Qt::ForegroundRole).value.color.should == Qt::Color.new(Qt::green)
        @model.data(mock_index(0,0), Qt::ForegroundRole).should_not be_valid
    end


Here is a minimal ruby dcop slot implementation:
    def mock_index(row, col)
        stub(:row => row, :column => col)
    end


      require 'Korundum'
    def have_flag(flag)
        return simple_matcher("A flag that matches " + flag.to_s) { |given| (given & flag) != 0 }
      class MyWidget < KDE::PushButton
    end
        k_dcop 'QPoint mySlot(int,QString)'
end
</syntaxhighlight>
        def initialize(parent, name)
              super
          end
        def mySlot(counter,greeting)
              return Qt::Point.new(50, 100)
        end
      end  


This slot is passed an integer and a string, and returns a Qt::Point.
=== Testing Out Signals and Slots ===
Below is a simple class which can be used to test out a class via the signals it emits:


Note that the class doesn't have to inherit from DCOPObject. If you include a 'k_dcop' slots declaration a 'listener' dcop object instance is created automatically, and these four methods are added to your class:
<syntaxhighlight lang="ruby">
class RubySignalSpy < Qt::Object
    def self.create(*args, &block)
        Class.new(self).new(*args, &block)
    end


      interfaces()
    def count(name)
      functions()
        @calls[name].size
      connectDCOPSignal()
    end
      disconnectDCOPSignal()


The name of the object is always the ruby classname, and you can only instantiate one instance for each ruby class that has 'k_dcop' declarations. See examples/dcop/dcopslot.rb and dcopsignal.rb for an example of the simplest approach.
    def params(name, invocation = 0)
        @calls[name][invocation]
    end


If you wish to use the full functionality of a DCOPObject, you can subclass it and call all the methods, not just the four above. Additionally, you can instantiate more than one instance per class and rename the dcop object with the setObjId() method or by passing the name to the constructor. See the examples/dcop/petshop.rb code for an example of a more complex dcop object.
    def method_missing(name, *args, &block)
        @calls[name.to_sym] << args
        exec_action_for(name, args)
    end


Define a dcop slot like this in one ruby program:
    def responds_to?(name)
        true
    end


      k_dcop 'QPoint getPoint(QString)'
  private
    def initialize
      def getPoint(msg)
        @calls = {}
          puts "message: #{msg}"
        def @calls.[](index)
          return Qt::Point.new(50, 100)
            super || self[index] = []
      end
        end
        @actions = {}
        super
    end


Call it from another program and print the reply, like this:
    def mocked_slots(*names, &block)
        slots *names
        names.each { |name| @actions[name] = block }
    end


      dcopRef = KDE::DCOPRef.new("dcopslot", "MyWidget")
    def exec_action_for(name, args)
        @actions[name].call(self, args) if @actions[name]
    end


There are three different ways to specify a DCOP call:
    def slots(*args)
        self.class.slots(*args)
    end
end
</syntaxhighlight>


      res = dcopRef.call("getPoint(QString)", "Hello from dcopcall")
<syntaxhighlight lang="ruby">
      res = dcopRef.call("getPoint", "Hello from dcopcall")
      it "Should be able to emit a signal when called" do
      res = dcopRef.getPoint("Hello from dcopcall")
        reciever = RubySignalSpy.create do
            slots "recieved(int, int)"                     # Explicitly name slots with parameters
            mocked_slot :some_other_slot do |spy, params|  # Pass a block to be executed when called
            end                                            # You must call mocked_slot with a symbol
        end


If the dcop slot has a 'void' or 'ASYNC' type, the result will be true if the call succeeds or nil if it fails
        class ClassWeAreTesting < Qt::Object
            signals "sending(int, int)"
            def broadcast
                emit sending(4, 2)
            end
        end


==DCOP Attributes==
        sender = ClassWeAreTesting.new


You can set a dcop attribute like this, instead of calling:
        Qt::Object.connect(sender, SIGNAL("sending(int, int)"), reciever, SLOT("recieved(int, int)"))
        sender.broadcast
        reciever.count(:recieved).should == 1              # Get count of calls
        reciever.params(:recieved, 0).should == [4, 2]      # Get the parameters of nth invocation
    end
</syntaxhighlight>


      klipper.setClipboardContents("Hello there klipper")
=== Testing UI Classes ===
It is much more difficult to test UI classes. In most cases, you will need to instantiate a QApplication so that you can create your widgets.  


Assign to the DCOP attribute:
Some rudimentary tests can be written by simulating clicks are various locations. Watch this space as more tests get written
<syntaxhighlight lang="ruby">
describe SomeTableView do
    before(:all) do
        @app = Qt::Application.new(ARGV)
        @view = SomeTableView.new
    end


       klipper = DCOPRef.new("klipper", "klipper")
    it "Should accept a mouse click on second row"        
      klipper.clipboardContents = "Hello there klipper"
        @row2 = @view.rowViewportPosition 1
        @view.mousePressEvent(Qt::MouseEvent.new(Qt::Event::MouseButtonPress, Qt::Point.new(0,@row2), Qt::LeftButton, Qt::LeftButton, Qt::NoModifier))
        # Assert something here, such as that a signal has been emitted
    end


Amaze your friends! Do the programming equivalent of leaping over tall buildings in one bound! Here with one line of quite clear code, we read a file from disc and assign it the 'clipboardContents' klipper attribute via dcop:
    after(:all) do
        @app.dispose!
    end
end
</syntaxhighlight>


      klipper.clipboardContents = IO.readlines("myfile").to_s
=KDE Specific Infomation=
Instead of <syntaxhighlight lang="ruby">require 'Qt4'</syntaxhighlight>, use<syntaxhighlight lang="ruby">require 'korundum4'</syntaxhighlight> for KDE programs.


==DCOP Predicates==
The KDE K* classes such as KApplication are renamed as KDE::Application. The other KDE classes are in the KParts::, KIO:: or DOM:: namespaces, with the same names as their C++ counterparts.


Instead of:
Use the 'rbkdeapi' script to introspect the Korundum api from the command line. For example:


      result = dcopRef.isFoo()
<syntaxhighlight lang="bash">
$ rbkdeapi KDE::Action
</syntaxhighlight>


You can use this more rubyish form:
Will list all the methods in the KDE::Action class. There are currently (as at KDE 3.3 beta 2) 977 classes/30841 methods in the Smoke library runtime, so the coverage of the Qt/KDE api is pretty complete.
 
      if dcopRef.foo?
          puts "foo is true"
      else
          puts "foo? is false"
      end
 
Similarly you can use foo? as an alias for methods of the form hasFoo(). See examples/dcop/dcoppredicate.rb and dcopslot.rb
 
==Underscore to CamelCase DCOP method name conversion==
 
Any underscores in a method name are removed, and the following character is capitalised. For example:
 
      res = dcopRef.get_point("Hello from dcopsend")
 
Is a synonym for:
 
      res = dcopRef.getPoint("Hello from dcopsend")
 
==Send to a DCOPRef==
 
There are two different ways to specify a DCOP send:
 
      res = dcopRef.send("mySlot(QString)", "Hello from dcopsend")
      res = dcopRef.send("mySlot", "Hello from dcopsend")
 
The result will either be true or false (but not nil for fail like DCOPRef.call() method described above).
 
When a call of the form 'dcopRef.getPoint(5, "foobar")' is made, the C++ type signature is obtained from the list of those returned by DCOPRef.functions(). However, if a method name is overloaded the ruby argument types are used to derive a type signature, in order to resolve the call like this:
 
      String => QString
      Float => double
      Integer => int
      TrueClass|FalseClass (ie 'true' or 'false') => bool
      Qt::Widget etc => QWidget
      KDE::URL etc => KURL
      Array => QStringList
 
Specify the full C++ type signature using the form 'dcopRef.call("getPoint(int,QString)", 5, "foobar")' if these rules fail to pick the right method.
 
==Defining DCOP Signals==
 
      k_dcop_signals 'void testEmitSignal(QString)'
      def doit()
          emit testEmitSignal("Hello DCOP Slot")
      end
 
Connect slot 'mySlot' to a DCOP signal like this:
 
      res = slottest.connectDCOPSignal("dcopsignal",
                              "SenderWidget",
                              "testEmitSignal(QString)",
                              "mySlot(QString)",
                              true)


=Build dependencies=
=Build dependencies=


* ruby 1.8 or greater
* ruby 1.8 or greater (svn trunk works with 1.9.1)
* automake 1.7 or greater
* cmake 2.6 or greater
* Qt 3.1 or greater
* Qt 4.0 or greater
* KDE 3.1 or greater (for korundum)
* KDE 4.1 or greater (for korundum)


=Tutorials=
=Tutorials=
There is a ruby translation of [http://developer.kde.org/language-bindings/ruby/tutorial/tutorial.html Qt Tutorial #1], and the corresponding ruby code is in qtruby/rubylib/tutorial/t1 to t14.
There is a ruby translation of [http://developer.kde.org/language-bindings/ruby/tutorial/tutorial.html Qt Tutorial #1], and the corresponding ruby code is in qtruby/rubylib/tutorial/t1 to t14.


And a Qt4 version of the same tutorial translated to Ruby by Darshan Ishaya [http://www.darshancomputing.com/qt4-qtruby-tutorial/ Qt4 Tutorial #1]  
And a Qt4 version of the same tutorial translated to Ruby by Darshan Ishaya [[Development/Tutorials/Qt4_Ruby_Tutorial|Qt4 Ruby Tutorial]]  


[http://developer.kde.org/language-bindings/ruby/tutorial2/tutorial2.html Qt Tutorial #2], a Charting Application with ruby code in qtruby/rubylib/examples/qt-examples/chart.
[http://developer.kde.org/language-bindings/ruby/tutorial2/tutorial2.html Qt Tutorial #2], a Charting Application with ruby code in qtruby/rubylib/examples/qt-examples/chart.
Line 405: Line 580:


The book [http://www.pragmaticprogrammer.com/titles/ctrubyqt/ Rapid GUI Development with QtRuby] is now available.
The book [http://www.pragmaticprogrammer.com/titles/ctrubyqt/ Rapid GUI Development with QtRuby] is now available.
There is also an approach to create an [[/Ruby-Qt/KDE Book|Ruby-Qt/KDE Book]] under a free license. The content will be created in this wiki. The book made with latex will be derived from the content in the wiki. Any Questions? Contact [[User:SaLOUt|me]]!


=Download=
=Download=
Line 419: Line 596:
* [http://weblog.nomejortu.com/x-windows/ruby-qt-custom-widget-example ruby Qt custom widget example]
* [http://weblog.nomejortu.com/x-windows/ruby-qt-custom-widget-example ruby Qt custom widget example]
* [http://weblog.nomejortu.com/x-windows/ruby-qttreewidget-example ruby Qt::TreeWidget example]
* [http://weblog.nomejortu.com/x-windows/ruby-qttreewidget-example ruby Qt::TreeWidget example]
* [http://www.ruby-forum.com/topic/189346#new Very useful link how to create your first Qt window dialog]


[[Category:Ruby]]
[[Category:Ruby]]

Latest revision as of 14:15, 31 May 2019


This page has been archived
The information on this page is outdated or no longer in use but is kept for historical purposes. Please see the Category:Archives for similar pages.
Note
The information below applies to older versions of Qt only. There are currently no Ruby bindings for Qt 5 and KDE Frameworks 5 available.


Warning
Some important links are non-functional, specially the official Korundum page. Until we solve this problem you can find the source code at kdebindings project page


Very complete bindings to both the KDE API and the Qt APIs. The Korundum package includes both a QtRuby Qt-only binding along with the full combined Qt/KDE one. The QtRuby package contains just Qt bindings with no dependencies on KDE.

Korundum/QtRuby - Ruby-KDE/Qt bindings

The book Rapid GUI Development with QtRuby (for Qt version 3.x) is available.

Being Smoke-based bindings means that they offer full access to most KDE 4.x and Qt 4.x classes.

QtRuby

Hello world example:

#!/usr/bin/ruby -w
require 'Qt4'
a = Qt::Application.new(ARGV)
hello = Qt::PushButton.new("Hello World!")
hello.resize(100, 30)
hello.show
a.exec

Hello Qt example in a more 'Rubyish' way:

require 'Qt4'

Qt::Application.new(ARGV) do
    Qt::Widget.new do

        self.window_title = 'Hello QtRuby v1.0'
        resize(200, 100)
    
        button = Qt::PushButton.new('Quit') do
            connect(SIGNAL :clicked) { Qt::Application.instance.quit }
        end

        label = Qt::Label.new('<big>Hello Qt in the Ruby way!</big>')
        
        self.layout = Qt::VBoxLayout.new do
            add_widget(label, 0, Qt::AlignCenter)
            add_widget(button, 0, Qt::AlignRight)
        end
        
        show
    end
    
    exec
end

Current api coverage overview

Available calls

You can call all Qt public and protected methods, and all friend methods such as bitBlt() etc

Virtual methods

All virtual methods can be overridden, not just event handlers

Properties

'foobar = 5' is a synonym for 'setFooBar(5)'

Use either CamelCase or lowercase with underscore naming

Any underscores in method names are removed, and the following character is capitalised. For example, you can use either of these two forms to call the same method:

create_standard_status_bar_action()
createStandardStatusBarAction()

Operator overloading

The full range of Qt operator methods is available, for example:

p1 = Qt::Point.new(5,5)   => (5, 5)
p2 = Qt::Point.new(20,20) => (20, 20)
p1 + p2                   => (25, 25)

Declare signals and slots

Signals and slots are declared as list of strings like this:

slots 'setColor(QColor)', 'slotLoad(const QString&)'..
signals 'clicked()'..

For slots and signals without arguments you can use Ruby symbols:

slots :slotLoad
signals :clicked

Currently C++ type signatures must be used, a future version of QtRuby will allow ruby type signatures instead. (see the section on emitting Ruby Classes)

Connect slots and signals like this:

Qt::Object.connect( @colormenu, SIGNAL( "activated(int)" ),
                  self, SLOT( "slotColorMenu(int)" ) )

There is also two another possibilities:

connect(:mysig, mytarget, :mymethod))
connect(SIGNAL('mysignal(int)'), mytarget, :mymethod))

Or you can connect signal to a block:

quit_button.connect(SIGNAL :clicked) { $qApp.quit }

And emit signals like this:

emit colorChanged( black )

Emitting Ruby Classes

Ruby classes can be emitted by embedding them inside a QVariant, and emitting the QVariant.

The following code provides a method called to_variant that can be used to easily convert objects to Variants

class Qt::RubyVariant < Qt::Variant
    def initialize(value)
        super()
        @value = value
    end

    attr_accessor :value
end

class Object
    def to_variant
        Qt::RubyVariant.new self
    end
end

Note: as of KDE 4.5 you can simply use

variant = Qt::Variant.fromValue(my_ruby_object)

to create a QVariant that contains your ruby object. To get it back, you just call Qt::Variant#value as usual.

This can be used as follows

class MyObject < Qt::Object
    signals "mySignal(QVariant)"
    def doEmit
        # since KDE 4.5:
        # emit mySignal(Qt::Variant.fromValue(ruby_object))
        emit mySignal(ruby_object.to_variant)
    end

    slots "mySlot(QVariant)"
    def mySlot(variant)
        ruby_object = variant.value
    end
end

Alternate way to emit Ruby Classes

You can also try to emit a ruby class by emitting it's object_id (either as an Integer or a QVariant), and use ObjectSpace._id2ref to get the object back.

class Object
    def to_variant
        Qt::Variant.new object_id
    end
end

class Qt::Variant
    def to_object
        ObjectSpace._id2ref to_int
    end
end

Constructors

You can call constructors in the conventional style:

quit = Qt::PushButton.new("Quit", self, "quit")

Or you can pass a block if you prefer:

w = MyWidget.new { setCaption("foobar") }

The block will be called in the context of the newly created instance.

Ordinary arguments can be provided as well as a block at the end:

w = MyWidget.new(nil) { setCaption("foobar") }

They are run in the context of the new instance.

And there's more! You can also pass an arg to the block, and it will be run in the context of the arg:

w = MyWidget.new { |theWidget| theWidget.setCaption "foobar" }

Garbage Collection

When a ruby instance is garbage collected, the underlying C++ instance will only be deleted if it isn't 'owned' by a parent object. Normally this will 'just work', but there are occasions when you need to delete the C++ ahead of garbage collection, and whether or not it has a parent. Use the dispose(), isDisposed() and disposed? methods like this:

item2.dispose
if item2.disposed?
puts "item2 is disposed"
end

C++ 'int*' and 'int&' argument types

Ruby passes numeric values by value, and so they can't be changed when passed to a method. The Qt::Integer class provides a mutable numeric type which does get updated when passed as an argument. For example, this C++ method 'findByFileContent()':

# static Ptr findByFileContent( const QString &fileName, 
#                               int *accuracy=0 );
 
acc = Qt::Integer.new(0)
fc = KDE::MimeType.findByFileContent("mimetype.rb", acc)

It supports the arithmetic operators, and so expressions such as 'acc + 3' will work.

C++ 'bool*' and 'bool&' argument types

There is a similar problem for bool arg types, and the mutable Qt::Boolean class can be used like this:

# QFont getFont(bool * ok, const QFont&initial, 
#               QWidget* parent = 0, const char *name = 0);		
 		
ok = Qt::Boolean.new
font = Qt::FontDialog.getFont(ok, 
                    Qt::Font.new("Helvetica [Cronyx]", 10), 
                    self)
if !ok.nil? 
# font is set to the font the user selected
else 
# the user canceled the dialog
end

Use 'nil?' to test the value returned in the Boolean

C++ (const )(unsigned )char* argument types

In some cases Qt/KDE object "takes ownership" over Ruby String passed as char* argument type. Programmer needs to make sure that Ruby String is not being garbage collected or changed for the time it's being used by Qt/KDE object. It is also quite possible that Qt/KDE object will change and eventually free it(memory used internally by Ruby String to store its data). Be very careful when you call this kind of methods and make sure that there is no overloaded version witch accepts QString or QByteArray first!

C++ unsigned char* functions

Very few functions (as QImage::bits()) return a uchar* to directly manipulate data. These functions are not supported in Ruby and will throw an ArgumentError. More information on the mail list.

Debugging

If a method call can't be matched in the Smoke library giving a 'method_missing' error, first check that you are passing correct class instance that is properly initialized (with super method called in constructors of custom Qt classes descendants). You can also turn on debugging to trace the matching process:

a = Qt::Application.new(ARGV)
Qt.debug_level = Qt::DebugLevel::High
a.loadLibrary("foo")  # Non existent method

Will give the following output:

      classname    == QApplication
      :: method == loadLibrary$
      -> methodIds == []
      candidate list:
      Possible prototypes:
          static QWidget* QApplication::widgetAt(int, int, bool)
			...

Here, the list of candidate methods 'methodIds' is empty

Another debugging mechanism allows various trace 'channels' to be switched on.

You can trace virtual method callbacks:

Qt::Internal::setDebug(Qt::QtDebugChannel::QTDB_VIRTUAL)

Or trace QtRuby garbage collection:

Qt::Internal::setDebug(Qt::QtDebugChannel::QTDB_GC)

String i18n

QtRuby supports $KCODE values of 'u', 'e' and 's' or the corresponding '-K' options from the command line. Qt Designer .ui files have UTF-8 strings so if you use any 8 bit UTF-8 characters, you will need to set $KCODE='u' or use the -Ku command line option.

Other capabilities and offerings

Qt Designer

A 'rbuic4' tool is included in qtruby/tools/rbuic to compile .ui files into ruby code. As described above, Qt Designer uses UTF-8. In addition to the options in the original uic C++ utility an '-x' flag has been added. This will generate a top level stub in the code:

$ rbuic mainform.ui -x -o mainform.rb

Will add this to the end of the generated code:

if $0 == __FILE__
    a = Qt::Application.new(ARGV)
    w = MainForm.new
    w.show
    a.exec
end

Then you can test the example code straight away:

      $ ruby mainform.rb

Use the '-kde' option to require the 'korundum4' extension rather than the 'Qt4' one. If the '-x' option is used in conjunction, it generates a KDE top level. For example:

$ rbuic4 -x -kde knotifywidgetbase.ui -o knotifywidgetbase.rb

Will generate this top level code:

if $0 == __FILE__
    about = KDE::AboutData.new("knotifywidgetbase", 
 		                       "KNotifyWidgetBase", "0.1")
    KDE::CmdLineArgs.init(ARGV, about)
    a = KDE::Application.new()
    w = KNotifyWidgetBase.new
    w.show
    a.exec
end

Loading .ui files at runtime with Qt::UiLoader

Let's say you created a file in your project directory called 'gui.ui' using Qt Designer ('/usr/bin/designer', comes with Qt. At least on Arch). You can load it like so:

require 'Qt4'
require 'qtuitools'

class MyApp < Qt::Application
    def initialize
        super ARGV

        # 'gui.ui' was created with qt designer ('designer' on arch linux)
        file = Qt::File.new 'gui.ui' do
            open Qt::File::ReadOnly
        end
        
        window = Qt::UiLoader.new.load file

        file.close

        if window.nil?
            print "Error. Window is nil.\n"
            exit
        end 
        window.show
    end
end

a = MyApp.new
a.exec

API reference

Use the bin/rbqtapi tool to discover which methods are available in the QtRuby api. This command:

$ rbqtapi Qt::TextEdit

Will list all the methods in the Qt::TextEdit class

$ rbqtapi -rsetCaption

Lists all methods whose names contain the string 'setCaption'

Example programs

The best way to start programming QtRuby is to look at some existing code and start messing with it.. The are various samples under qtrubyexamples and korundum/examples.

Writing Unit Tests

Using Ruby allows you the power to leverage testing frameworks such as RSpec in order to unit and integration test your classes.

Most classes such as Models can be easily tested via the APIs they expose. Below is a small extract with some interesting tests from the mingle_mover project (http://github.com/gja/mingle_mover). The class being tested is a TableModel

Note how we create a stub to pass to QAbstractTableModel::data, which accepts a QModelIndex as an argument.

describe CardModel do
    it "Should Implement QAbstractTableModel" do
        CardModel.ancestors.should include Qt::AbstractTableModel
    end

    it "Should Not Be Editable" do
        @model.data(mock_index(1,2), Qt::EditRole).should_not be_valid
        @model.headerData(nil, nil, Qt::EditRole).should_not be_valid
        
        flags = @model.flags(nil)
        flags.should have_flag Qt::ItemIsEnabled
        flags.should have_flag Qt::ItemIsSelectable
        flags.should_not have_flag Qt::ItemIsEditable
    end

    it "Should not return any vertical headers" do
        @model.headerData(1, Qt::Vertical).should_not be_valid
    end

    it "Should color a row according to the status" do
        @model.data(mock_index(1,2), Qt::ForegroundRole).value.color.should == Qt::Color.new(Qt::red)
        @model.data(mock_index(0,2), Qt::ForegroundRole).value.color.should == Qt::Color.new(Qt::green)
        @model.data(mock_index(0,0), Qt::ForegroundRole).should_not be_valid
    end

    def mock_index(row, col)
        stub(:row => row, :column => col)
    end

    def have_flag(flag)
        return simple_matcher("A flag that matches " + flag.to_s) { |given| (given & flag) != 0 }
    end
end

Testing Out Signals and Slots

Below is a simple class which can be used to test out a class via the signals it emits:

class RubySignalSpy < Qt::Object
    def self.create(*args, &block)
        Class.new(self).new(*args, &block)
    end

    def count(name)
        @calls[name].size
    end

    def params(name, invocation = 0)
        @calls[name][invocation]
    end

    def method_missing(name, *args, &block)
        @calls[name.to_sym] << args
        exec_action_for(name, args)
    end

    def responds_to?(name)
        true
    end

  private
    def initialize
        @calls = {}
        def @calls.[](index)
            super || self[index] = []
        end
        @actions = {}
        super
    end

    def mocked_slots(*names, &block)
        slots *names
        names.each { |name| @actions[name] = block }
    end

    def exec_action_for(name, args)
        @actions[name].call(self, args) if @actions[name]
    end

    def slots(*args)
        self.class.slots(*args)
    end
end
      it "Should be able to emit a signal when called" do
        reciever = RubySignalSpy.create do
            slots "recieved(int, int)"                      # Explicitly name slots with parameters
            mocked_slot :some_other_slot do |spy, params|   # Pass a block to be executed when called
            end                                             # You must call mocked_slot with a symbol
        end

        class ClassWeAreTesting < Qt::Object
            signals "sending(int, int)"
            def broadcast
                emit sending(4, 2)
            end
        end

        sender = ClassWeAreTesting.new

        Qt::Object.connect(sender, SIGNAL("sending(int, int)"), reciever, SLOT("recieved(int, int)"))
        sender.broadcast
        reciever.count(:recieved).should == 1               # Get count of calls
        reciever.params(:recieved, 0).should == [4, 2]      # Get the parameters of nth invocation
    end

Testing UI Classes

It is much more difficult to test UI classes. In most cases, you will need to instantiate a QApplication so that you can create your widgets.

Some rudimentary tests can be written by simulating clicks are various locations. Watch this space as more tests get written

describe SomeTableView do
    before(:all) do
        @app = Qt::Application.new(ARGV)
        @view = SomeTableView.new
    end

    it "Should accept a mouse click on second row"        
        @row2 = @view.rowViewportPosition 1
        @view.mousePressEvent(Qt::MouseEvent.new(Qt::Event::MouseButtonPress, Qt::Point.new(0,@row2), Qt::LeftButton, Qt::LeftButton, Qt::NoModifier))
        # Assert something here, such as that a signal has been emitted
    end

    after(:all) do
        @app.dispose!
    end
end

KDE Specific Infomation

Instead of

require 'Qt4'

, use

require 'korundum4'

for KDE programs.

The KDE K* classes such as KApplication are renamed as KDE::Application. The other KDE classes are in the KParts::, KIO:: or DOM:: namespaces, with the same names as their C++ counterparts.

Use the 'rbkdeapi' script to introspect the Korundum api from the command line. For example:

$ rbkdeapi KDE::Action

Will list all the methods in the KDE::Action class. There are currently (as at KDE 3.3 beta 2) 977 classes/30841 methods in the Smoke library runtime, so the coverage of the Qt/KDE api is pretty complete.

Build dependencies

  • ruby 1.8 or greater (svn trunk works with 1.9.1)
  • cmake 2.6 or greater
  • Qt 4.0 or greater
  • KDE 4.1 or greater (for korundum)

Tutorials

There is a ruby translation of Qt Tutorial #1, and the corresponding ruby code is in qtruby/rubylib/tutorial/t1 to t14.

And a Qt4 version of the same tutorial translated to Ruby by Darshan Ishaya Qt4 Ruby Tutorial

Qt Tutorial #2, a Charting Application with ruby code in qtruby/rubylib/examples/qt-examples/chart.

The Qt Designer Color Tool Tutorial, with ruby code in qtruby/rubylib/designer/examples/colortool.

Paul Lutus has written a tutorial on how to get started with Ruby GUI programming with Qt

For KDE, there is a ruby translation of this KDE 3.0 tutorial originally written for C++ by Antonio Larrosa Jiménez. The sources are in korundum/rubylib/tutorials/p1 to p9.

The book Rapid GUI Development with QtRuby is now available.

There is also an approach to create an Ruby-Qt/KDE Book under a free license. The content will be created in this wiki. The book made with latex will be derived from the content in the wiki. Any Questions? Contact me!

Download

You can obtain recent SVN snapshots on the Rubyforge QtRuby/Korundum site.

More help

There are two IRC channels (#qtruby and #kde-ruby) in FreeNode. If you prefer e-mail, you can use the kde-bindings mailing-list (low traffic) or ask in the ruby-talk mailing list (you may use the Ruby Forum gateway to post in ruby-talk from web).

More information

A series of articles on ruby QT (inspired by the work done for the dradis project):