rock-qtbindings

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• (C) 2003-2007 Richard Dale All rights reserved. *

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• This program is free software; you can redistribute it and/or modify *
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Here is a Ruby SMOKE adaptor for Qt

Why ruby? From the rubytalk list

On 8/28/03 8:56 PM, "Scott Thompson" wrote:

: Can anyone give me a good reason why I would want to use Ruby over Python?

Ruby smells better than Python. Also, it has cuter girls.

Python sometimes tastes better if you prepare it right.

I hadn't noticed the odor thing. It does have a faintly floral aroma doesn't it.

Of course it is no surprise that you can get more and cuter girls with Rubies than you can with Pythons.

Scott

So there you have it! :)

Here is 'Hello World' in QtRuby:

#!/usr/bin/ruby -w

require 'Qt'

a = Qt::Application.new(ARGV) hello = Qt::PushButton.new("Hello World!") hello.resize(100, 30) hello.show a.exec

Ruby 1.8 is unfortunately implicitly required as with 1.6.x it is not possible to:

Make dynamic constants available (thus forcing syntax such as Qt.RichText rather than Qt::RichText)
Call super in the initialize method thus making subclassing of non trivial classes impossible

QtRuby features a very complete coverage of the Qt api:

- You can call all Qt public and protected methods, and all friend methods
	such as bitBlt() etc
	
- Virtual methods
	All virtual methods can be overriden, not just event handlers
	
- Properties 
	'fooBar = 5' is a synonym for 'setFooBar(5)'
	
- Predicates
	'if foo?' is a synonym for 'if isFoo()' or 'if hasFoo()'
	
- Use underscore naming for method names instead of camel case if you 
	prefer. 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()'..
		
	If the slots or signal have no arguments they can also be declared as
		Symbols:

		slots :click, :toggle
		signals :clicked

	Currently C++ type signatures must be used, a future version of QtRuby
		will allow ruby type signatures instead.
	
	Connect slots and signals like this:
				
		Qt::Object.connect( @_colormenu, SIGNAL( "activated( int )" ),
					 		self, SLOT( "slotColorMenu( int )" ) )

	And emit signals like this:
	
		emit colorChanged( black )

- 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() and isDisposed() methods like this:
	
		item2.dispose
		if item2.isDisposed
			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

- Debugging
	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:
	
		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.

- Qt Designer
	A 'rbuic4' tool is included in 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:
	
	$ rbuic4 mainwindowbase.ui -x -o mainwindowbase.rb
	
	Will add this to the end of the generated code:

		if $0 == __FILE__
			a = Qt::Application.new(ARGV)
			u = Ui_MainWindowBase.new
			w = Qt::MainWindow.new
			u.setupUi(w)
			w.show
			a.exec
		end
		
	Then you can test the example code straight away:
		
	$ ruby mainwindowbase.rb

- Loading .ui files at runtime with Qt::UiLoader
	You can load a Qt Designer .ui file at runtime with Qt::UiLoader,
	for example:
	
		require 'Qt'
		...

		loader = Qt::UiLoader.new
		
		file = Qt::File.new(":/forms/calculatorform.ui")
		file.open(Qt::File::ReadOnly)
		formWidget = loader.load(file, self)
		file.close
		
		@ui_inputSpinBox1 = findChild(Qt::SpinBox, "inputSpinBox1")
		@ui_inputSpinBox2 = findChild(Qt::SpinBox, "inputSpinBox2")
		@ui_outputWidget = findChild(Qt::Label, "outputWidget")
		
		Qt::MetaObject.connectSlotsByName(self)
		
		self.layout = Qt::VBoxLayout.new do |l|
			l.addWidget(formWidget)
		end

- API reference
	Use the bin/rbqtapi tool to discover which methods are available in
	the QtRuby api.
		
- 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/examples.

- Optional QScintilla text editing widget support
	Great for building your own ruby IDE..

- Optional Qwt scientific plotting library support

Have Fun!

-- Richard