Qt Technical Presentation

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QtTechnical Presentation

• Written by Eirik Aavitsland
• Qt Product Manager
• Trolltech

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Presentation Overview

• About Trolltech
• Overview of Qts architecture and features

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AboutTrolltech
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Trolltech

• Founded in 1994
• Offices
• Oslo, Norway (HQ)
• Santa Clara, California
• Brisbane, Australia
• Ownership
• Majority by employees
• Investments by Canopy Group, Inprise/Borland,
• Currently 75 employees and growing
• Main products Qt and Qtopia

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Product LineQt

• Platform-independent application framework

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Product lineQtopia

• Qt/EmbeddedQt for resource-constraineddevices
  and embedded OSs
• Qtopia Window system applications for PDAs,
  smartphones, etc.

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Commercial Qt usage

• Worldwide 2000 customers, including

Adobe, Agilent, ARM, Boeing, Bosch, Cadence,
Canon, CEA Technologies, ChevronTexaco,
DaimlerChrysler, Deutsche Telekom, Disney, Earth
Decision Sciences, ESA, Fraunhofer, HP, IBM,
Intel, JD Edwards, Lockheed Martin, LogicaCMG,
Mentor Graphics, NASA, NEC, NTT, PGS, Pioneer,
Rohde Schwarz, Scania, Schlumberger, Sharp,
Shell, Siemens, Sony, STN-Atlas, Stryker
Leibinger, Synopsys, Thales...
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Non-commercial Qt usage

• Trolltech has been a key player in the Linux
  marketplace since 1996
• Qt is a critical component in all Linux
  distributions
• Qt is the basis of KDE
• ...and thousands of other free software projects
• Widely used by Linux community
• thousands of developers
• millions of end-users

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QtFeatures
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Overview

• Qt is a C application framework
• Class library / Application Programmers
  Interface (API)
• Development tools
• Developers use the standard native tools to build
  Qt apps
• C compiler
• Debugger
• IDE
• etc.

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Multi-platform

• Qt provides a platform-independent encapsulation
  of the local window system and operating system
• The Qt API is the same on every platform
• Write once, compile everywhere
• Native executables on each platform

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Pros of Qts platform independence

• Single-source
• Shorter development time
• Less maintenance
• Change or add new target platforms at any time
• Avoid hard decisions on target platform
• Insulated against OS and window system changes
• Well prepared for future OSs and window systems

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Qt vs. Java

• Qt gives the same platform independence as Java
• But Qt applications must be recompiled for each
  platform
• Qt apps dont need a Virtual Machine
• Qt apps more lightweight, significantly faster
• It is easier to interface other libraries with Qt
• Java may arguably be a nicer language than C
• ...but Qt makes C nicer in various ways
• Handles garbage collection of Qt classes
• Adds signals and slots for inter-object
  communication
• Avoid use of, and does not require use of,
  advanced C

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Class library overview

• Full set of GUI classes
• Widget set and GUI toolkit
• Operating system encapsulation classes
• OO, C class interface to C system calls
• SQL database access classes
• Data storing and retrieval
• Utility classes
• Commonly useful classes
• Integration Migration classes
• Using Qt with other libraries and legacy code

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GUI toolkit classes

• Full API to easily create the GUI
• Like MFC, Motif or Swing, but nicer...
• Complete set of GUI controls
• Menu bars, buttons, scroll bars, popup menus,
  etc. etc.
• Very simple to create custom controls
• Native Look Feel
• customizable / themeable

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OS encapsulation classes

• File directory handling
• Date time
• Registry / preferences
• Networking
• URL, socket, TCP, DNS, FTP, HTTP
• Process handling
• fork, terminate, kill, stdin/stdout/stderr I/O
• Threading
• start, terminate, semaphore, mutex, wait
• Dynamic library loading

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SQL database classes

• Store, retrieve, query, traverse modify DB data
• Database-independent API
• Oracle, Sybase/MS SQL Server, MySQL, PostgreSQL,
  ODBC
• DB-aware widgets
• editable forms and tableviews

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Utility classes

• String and regular expressions
• Unicode
• Text and binary I/O
• codecs
• Collections
• Optional alternatives to STL collections
• XML I/O
• Parser with SAX2 interface
• DOM level 2 implementation

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Integration Migration classes

• OpenGL
• 3D graphics rendering in a Qt widget
• ActiveX
• Host ActiveX controls in a Qt app
• Use Qt to create ActiveX controls
• Motif
• co-exist with legacy Motif code stepwise
  migration
• Microsoft Foundation Classes
• co-exist with legacy MFC code stepwise migration
• Netscape Plugins
• Create Netscape/Mozilla/Opera LiveConnect plugins
  with Qt

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Development ToolsOverview

• Qt Designer
• Visual GUI builder
• Qt Linguist
• Language translators tool
• Qt Assistant
• Help browser
• qmake
• Makefile generator

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Qt Designer

• WYSIWYG, drag drop GUI builder
• Widget properties editor
• Supports the Qt auto-layout system
• Designs stored in open, documented XML format
• Does not interfere with users source code

MyDialog.xml
MyDialogBase.cpp
uic
MyDialog.cpp
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Documentation

• Reference Manual
• HTML
• generated from the source code
• Fully cross-referenced
• Browsable from Qt Assistant
• or normal web browser doc.trolltech.com
• Tutorials
• Examples
• Qt programming books

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Services

• Maintenance
• Maintenance releases every 6-10 weeks
• Feature releases 1-2 times per year
• Support
• Email-based
• Training
• On-site or open enrollment
• Consulting
• Partner companies

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Qt Architecture Signals Slots

• Type-safe callback mechanism
• Object-oriented
• Facilitates loose coupling / encapsulation
• Sender and receiver does not know about each
  other
• 1-to-many, many-to-1, many-to-many

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Thank you