Cross Platform Development Focusing on Trolltech QT

1
Cross Platform DevelopmentFocusing on Trolltech
QT

• By Gabriel Johnson

2
Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform DevelopmentFocusing on Trolltech
QT
By Gabriel Johnson
Cross Platform Development
3
Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development
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Why Cross Platform?

• The computing world is becoming increasingly
  diverse
• With the right tools it can be painless
• Open up product to new markets
• Open up product to new users

Cross Platform Development
5
Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development
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Advantages

• New Target Market
• Support Existing Customers
• Choice
• Code Quality
• Financial Reasons
• Its Cool and Gives Warm Fuzzies

Cross Platform Development
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Disadvantages

• Cost of Training
• Cost of Purchasing
• Testing Time
• Managing Multiple Releases
• Dependent on Tools

Cross Platform Development
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Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Considerations
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development
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Design Considerations

• Language
• Use Standards-Based Persistent Storage
• Make Business Logic Abstract
• Closer to the User Means Less Portability
• Use XML for Standardized, Interoperable
  Communications between Subsystems
• Avoid Hiding The Power of a Specific Platform in
  the Name of Portability

Cross Platform Development
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Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Considerations
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development
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Design Issues

• Individual Compilers
• Follow language Standards
• Avoid Compiler Macros or Functions
• Individual Platforms
• Platform Specific Libraries are Necessary

Cross Platform Development
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Example

• MyCreateDialogBox()
• if (this is a Windows machine)
• call the Windows library CreateDialog()
  function
• else if (this is a Mac)
• call the Mac library's dialog creation
  function
• else if (this is a UNIX box)
• call the X Window System's dialog creation
  function

Cross Platform Development
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Design Issues

• Individual Compilers
• Follow language Standards
• Avoid Compiler Macros or Functions
• Individual Platforms
• Platform Specific Libraries are Necessary
• Platform Idiosyncrasies

Cross Platform Development
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Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Considerations
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development
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Tools

• WxWidgets
• Java
• Python
• MONO
• QT

Cross Platform Development
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Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Considerations
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development
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QT Overview

• Qt is a complete C application development
  framework, including
• A comprehensive C class library
• RAD GUI development tool
• Internationalization tool

Cross Platform Development
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QT Overview

• QT is Cross Platform
• The Qt API and tools are consistent across all
  supported platforms
• Consequence for users and customers
• OS Choices Include
• Windows 95 through Server 2003
• Mac OS X
• Linux and embedded Linux
• AIX, BSD/OS, FreeBSD, HP-UX, IRIX, NetBSD,
  OpenBSD, Solaris, Tru64 UNIX

Cross Platform Development
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Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Considerations
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development
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QT Features

• Qt provides a platform-independent encapsulation
  of the local window system and operating system
• The Qt API is identical on every platform,
  applications are compiled to native executables
• Result Write once, compile everywhere

Cross Platform Development
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Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Considerations
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development
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Signals and Slots

• Unique inter-object communication mechanism,
  provides
• Type-safe callback between objects
• Facilitates loose coupling / encapsulation
• Sender and receiver does not know about each
  other
• 1-to-many, many-to-1 communication between
  objects
• Fully Object-oriented

Cross Platform Development
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Signals and Slots
Cross Platform Development
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Signals and Slots

• class Foo public QObject
• Q_OBJECT
• public
• Foo()
• int value() const
• return val
• public slots
• void setValue( int )
• signals
• void valueChanged( int )
• private int val

Cross Platform Development
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Signals and Slots

• void FoosetValue( int v )
• if ( v ! val )
• val v
• emit valueChanged(v)

Cross Platform Development
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Signals and Slots

• Foo a, b
• connect(a,SIGNAL(valueChanged(int)),
• b, SLOT(setValue(int)))
• b.setValue( 11 )
• a.setValue( 79 )
• b.value()

Cross Platform Development
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Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Considerations
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development
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Class Library

• GUI Toolkit Classes
• Full API to easily create the GUI
• Complete set of GUI controls
• Native look feel
• OS encapsulation Classes
• File directory handling
• Date time
• Registry / preferences
• Networking
• Process handling
• Threading
• Dynamic library loading

Cross Platform Development
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Class Library

• SQL Database Classes
• Database operations
• Database-independent API
• DB-aware widgets
• Utility Classes
• String and regular expressions
• Text and binary I/O
• Collections
• XML I/O
• Integration and Migration Classes
• OpenGL
• ActiveX
• Netscape Plugins

Cross Platform Development
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Overview

• Why do Cross Platform Development?
• Advantages and Disadvantages
• Design Considerations
• Design Issues
• Tools
• QT Overview
• QT Features
• Signals and Slots
• Class Library
• Designer

Cross Platform Development