1. GUIs Basic Concepts

2. GUI GUI : Graphical User Interface Window/Frame : a window on the screen Controls/Widgets : GUI components

3. QT QT – layer of code to enable platform independent applications

4. QT Must add QT += widgets to.pro file – Tells QTCreator to look for those.h files / libraries

5. QT QApplication : class that manages resources, runs event loop – Create BEFORE anything GUI related – exec starts loop Last thing main does returns when all windows closed

6. QObject All GUI components are QObjects

7. Most Important Widgets Display text : Qlabel Text input : QLineEdit Button : QPushButton

8. Making a Window Any Qwidget can be a window – Call show method

9. Styling Can modify style through code:

10. Styling Can style with HTML within strings:

11. Styling Can apply style sheets to widgets

12. Event Handling & Layout

13. Event Based Programming Event : anything that happens – Window resized – Button pressed – Network connection closes

14. Event Based Programming Event : anything that happens – Window resized – Button pressed – Network connection closes Event based programs: – Enter infinite loop – Wait for events to happen – respond to them

15. Notifications Callback : – Way to register a function to be called in certain situation

16. Notifications Callback : – Way to register a function to be called in certain situation Function Pointer : stores address of a function – Type depends on return type and parameters

17. Function Pointers Name of function by itself is memory address Use to set function pointers:

18. Define Compiler macro – Preprocessor definition that replaces your source code with something more complex

19. Slots & Signals In QT – Signal : a message that a Widget can send – Slot : a function that can receive a message Signals wired to 0+ slots On event, sends signal to each listening slot

20. A Working Button Want a button that quits program:

21. A Working Button Want a button that quits program: Need to hook a signal from Button To slot in application

22. A Working Button Want a button that quits program: Need to hook a signal from Button To slot in application

23. Quitting Qobject::connect function hooks signal to slot – SIGNAL / SLOT ugly macros Address of widget Function to use as SIGNAL / SLOT

24. Layout Cross platform /resizeable GUIs need to be flexible Place components in layout boxes (sizers) – Components request needed size – Let layout boxes organize components

25. A Simple QT Layout Layout widgets – Invisible boxes that group widgets QVBoxLayout : Vertical group QHBoxLayout : Horizontal group

26. In Code Make widgets Add to layout

27. Behaviors Behavior hookup:

28. Behavior Errors Hookup happens at runtime… watch for errors in Application Output – Stuff inside SLOT / SIGNAL just treated as strings!