1. Chapter 4 Windows Forms GUI/EDP
Yingcai Xiao

2. .NET GUI
Forms and Controls

3. Concepts: GUI
Windows Forms—for writing GUI based applications (Windows Applications).
GUI: Graphical User Interface, to make programs easy to use, WYSIWYG (What you see is what you get).
Designing GUI-based Applications: Look & Feel
Look => Appearance (Layout Design)
Feel => Response (Event Handling)
User => Button Click => Event => Event Handler (a method).
GUI-based application => Event-driven programming
Two main tasks of GUI-based EDP:
Design interface appearance (look)
Implement even handlers (feel).

4. Concepts: GUI Design Principles
Users first: let users control the program not the other way around.
Elegant: simple but powerful. E.g.: iPot, iPhone, Google
Intuitive: don’t need too much training to use it. Compare operating interfaces of cars and airplanes.
Clarity: use icons and keywords that are standardized or clearly defined. (AWK?). Give users hints when they hesitating.
Hierarchical: only put the most frequently used and most important controls at the top level.
Speedy: users do not have patience to wait for too long.
Forgiving: allow users to make mistakes. Undo and redo.
Alignment: use tables.
Internationalization: use symbols.
More:
Day stopped here. 2/9/2016

5. .NET GUI Classes (Event Generators)
GUI Items are defined in System.Windows.Forms.
System.Windows.Forms.Form class: all forms derive from it.
Properties (can be treated as “public” data members):
ClientRectangle (drawing area not including the borders) ClientSize
BorderStyle
Text (Title Bar)
Methods:
OnPaint (event handler for the PAINT event)

6. Controls (Windows GUI Items)
System.Windows.Forms Control Classes 
Class
Descriptions
Button
Push buttons
CheckBox
Check boxes
CheckedListBox
List boxes whose items include check boxes
ComboBox
Combo boxes
DataGrid
Controls that display tabular data
DataGridTextBox
Edit controls hosted by DataGrid controls
DateTimePicker
Controls for selecting dates and times

7. Controls (Windows GUI Items) Cont.
System.Windows.Forms Control Classes 
GroupBox
Group boxes
HScrollBar
Horizontal scroll bars
Label
Label controls that display static text
LinkLabel
Label controls that display hyperlinks
ListBox
List boxes
ListView
List views (display flat lists of items in a variety of styles)
MonthCalendar
Month-calendar controls

8. Controls (Windows GUI Items) Cont.
System.Windows.Forms Control Classes 
NumericUpDown
Spinner buttons (up-down controls)
PictureBox
Controls that display images
PrintPreviewControl
Controls that display print previews
ProgressBar
Progress bars
PropertyGrid
Controls that list the properties of other objects
RadioButton
Radio buttons
RichTextBox
Rich-edit controls

9. Controls (Windows GUI Items) Cont.
System.Windows.Forms Control Classes 
StatusBar
Status bars
TabControl
Tab controls
TextBox
Edit controls
ToolBar
Toolbars
ToolTip
Tooltips
TrackBar
Track bars (slider controls)
TreeView
Tree views (display hierarchical lists of items)
VScrollBar
Vertical scroll bars

10. Programming a GUI APP using VS
Start Visual Studio
New project
Windows Forms Application
Toolbox->All Windows Forms->Common Controls->Button
drag it to Form1
Double click on button1 in Form1
Add to button1_Click
Text = "Hello!";
Build and run
Day Finished

11. Programming a GUI APP using Notepad
Use Notepad to write the program
Create your form (GUI) by sub-classing System.Windows.Forms.Form.
Add controls (GUI items) to the form.
Code your program logic.
Compile the program using csc.
Example:
T:\Xiao\Windows Programming\Examples\C4\DialogDemo\DialogDemo.cs

12. Programming a Control 1. Instantiate the corresponding control class.
2. Initialize the control by setting its property values.
Add the control to the form by calling
the “Add” method of the form’s Controls collection.
4. Map event handlers to the events.
5. Implement the event handlers.
Even 2/9/2016 needs to read app6 code on EDP, Day done.

13. Adding a Button to a Form
//Create and initialize the button
Button MyButton = new Button ();
MyButton.Location = new Point (16, 16);
MyButton.Size = new Size (96, 24);
MyButton.Text = "Click Me";
// add the button to the form’s Controls collection.
Controls.Add (MyButton);
// Add event handlers to events
MyButton.Click += new EventHandler (OnButtonClicked);
// Write the event handlers
void OnButtonClicked (Object sender, EventArgs e){… }
T:\Xiao\Windows Programming\Examples\C4\DialogDemo\DialogDemo.cs

14. Common Dialog Classes Defined in System.Windows.Forms
Dialog Boxes
Common Dialog Classes Defined in System.Windows.Forms
Class
Dialog Type
ColorDialog
Color dialog boxes for choosing colors
FontDialog
Font dialog boxes for choosing fonts
OpenFileDialog
Open File dialog boxes for choosing files
PageSetupDialog
Page Setup dialog boxes for entering page setup parameters
PrintDialog
Print dialog boxes for entering print parameters
SaveFileDialog
Save File dialog boxes for entering file names

15. DialogDemo.cs class MyDialog : Form { Label WidthLabel;
TextBox WidthBox;
Button OKButton;
public int UserWidth {
get { return Convert.ToInt32 (WidthBox.Text); }
set { WidthBox.Text = value.ToString (); } }
public MyDialog () {
// Initialize the dialog's visual properties
ClientSize = new Size (296, 196);
StartPosition = FormStartPosition.CenterParent;
FormBorderStyle = FormBorderStyle.FixedDialog;
Text = "Edit Ellipse";
ShowInTaskbar = false;
Day to start with real code and GDI

16. DialogDemo.cs // Create the dialog's controls
WidthLabel = new Label ();
WidthLabel.Location = new Point (16, 16);
WidthLabel.Size = new Size (48, 24);
WidthLabel.Text = "Width";
WidthBox = new TextBox ();
WidthBox.Location = new Point (64, 12);
WidthBox.Size = new Size (96, 24);
WidthBox.TabIndex = 1;

17. DialogDemo.cs OKButton = new Button ();
OKButton.Location = new Point (184, 12);
OKButton.Size = new Size (96, 24);
OKButton.TabIndex = 3;
OKButton.Text = "OK";
OKButton.DialogResult = DialogResult.OK;
AcceptButton = OKButton;
// Add the controls to the dialog
Controls.Add (WidthLabel);
Controls.Add (WidthBox);
Controls.Add (OKButton);
} }

18. DialogDemo.cs // In the parent form who starts the dialog:
MyDialog dlg = new MyDialog ();
if (dlg.ShowDialog (this) == DialogResult.OK) {
MyWidth = dlg.UserWidth; // get the input from the form
Invalidate (); // update the display of the parent form }

19. EDP

20. Concepts: EDP
Event-Driven Programming (EDP): Application waits (idles) after initialization until the user generates an event trough an input device (keyboard, mouse, …). The OS dispatches the event to the application who owns the active window. The corresponding event handler(s) of the application is invoked to process the event.

21. Events A menu in C++: char c; bool done = false; while(!done) {
cout << “Please make your selection, q to end:”
cin >> c;
switch(c) {
case “+”:
add( );
break;
case “-”:
sub( );
case “q”:
done = true; }
Event Loop
Event
Event Mapping
&
Even Dispatching
Event Handler

22. Key Components of EDP
(1) Event Generators:
keyboard, GUI items (buttons, menus, …), NUI devices.
(2) Events / Messages:
MouseClick, KeyDown, …
(3) Event Loop:
an infinite loop constantly waits for events.
(4) Event Mapping / Event Registration:
inform event dispatcher which event an event hander is for.
(5) Event Dispatcher:
dispatch events to the corresponding event handlers.
(6) Event Handlers:
methods for processing events.
OnMouseClick(), …

23. Key Components of EDP in .NET
(1) Event Generators
- commonly used GUI items are predefined.
- used by programmers / GUI designers.
(2) Events / Messages
- commonly used ones predefined.
(3) Event Loop: - taken care of by .NET.
(4) Event Mapping / Registration:
- implemented by .NET.
- to be used by the programmers
with appropriate matching:
event – delegate – even handler
(5) Event Dispatching: - taken care of by .NET.
(6) Event Handlers
- to be implemented by programmers.

24. .NET EDP Classes (1) GUI Items (Event Generators)
System.Windows.Forms.Form
Button, Dialog, ….
(2) Events: predefined Windows Messages:
e.g. WM_KEYDOWN
(3) Event Loop:
Built in System.Windows.Forms.Application Class:
static Run( ) method starts an application’s event loop.

25. .NET EDP Classes (4) Event Mapping / Registration:
System defined ones have their names fixed: e.g. OnPaint().
Other handlers need to be registered to the events with
their corresponding delegates by the programmer.
e.g. : MyButton.Click += new EventHandler (OnButtonClicked);
The Resource Editor will do this automatically
when the programmer double-clicks on a button.
(5) Event Dispatching:
Built in: HW->OS->Active Application->Event Object->
Delegate:Invoke->Handlers. .

26. .NET EDP Classes (6) Event Handlers: Programmers’ work.
void HandlerName (Object sender, EventArgs e)
//sender can be omitted.
HandlerName = “On” “EventName”
e.g. OnKeyDown(Object sender, EventArgs e);
.NET based GUI EDP:
Identify needed GUI items; code or visually design GUI.
Identify related event; register event handlers with the events via their delegates.
Implement event handlers.

27. Mouse and Keyboard Events/Handlers
OnKeyDown
A key is pressed
KeyEventArgs
OnKeyPress
A character is typed on the keyboard
KeyPressEventArgs
OnKeyUp
A key is released
OnMouseDown
A mouse button is pressed
MouseEventArgs
OnMouseEnter
The mouse cursor enters a form
EventArgs
OnMouseOver
The mouse cursor pauses over a form

28. Mouse and Keyboard Events/Handlers
OnMouseLeave
The mouse cursor leaves a form
EventArgs
OnMouseMove
The mouse cursor moves over a form
MouseEventArgs
OnMouseUp
A mouse button is released
OnMouseWheel
The mouse wheel is rolled

29. Mouse and Keyboard Events/Handlers
WM_KEYDOWN
protected override void OnKeyDown (KeyEventArgs e) {
// from the form     
if (e.KeyCode == Keys.F1) // Function key F1 was pressed
{ … } }
WM_CHAR protected override void OnKeyPress (KeyPressEventArgs e) {    
if  (e.KeyChar == 'C') { … } // Do something

30. Other Form-Level Events
OnActivated
A form is activated
OnClosed
A form is closed
OnClosing
A form is about to close
OnDeactivate
A form is deactivated
OnGotFocus
A form receives the input focus
OnLoad
A form is created
OnLocationChanged
A form is moved
OnLostFocus
A form loses the input focus
OnPaintBackground
A form’s background needs repainting
OnSizeChanged
A form is resized

31. Main Menus: top-level menu.
// Create a MainMenu object
MainMenu menu = new MainMenu ();
// Add a File menu and populate it with items
MenuItem item = menu.MenuItems.Add ("&File");
item.MenuItems.Add ("&New", new EventHandler (OnFileNew));
item.MenuItems.Add ("&Open...", new EventHandler (OnFileOpen));
// Add an Edit menu and populate it, too
item = menu.MenuItems.Add ("&Edit");
item.MenuItems.Add ("Cu&t", new EventHandler (OnEditCut));
Processing Menu Commands
void HandlerName (Object sender, EventArgs e)

32. Context Menus Context Menus: pop up context menus
ContextMenu menu = new ContextMenu ();
menu.MenuItems.Add ("&Open", new EventHandler (OnOpen));
menu.MenuItems.Add ("&Rename", new EventHandler (OnRename));
menu.MenuItems.Add ("&Delete", new EventHandler (OnDelete));
menu.Show (this, new Point (x, y));
Menu Item States: item.Checked = true;

33. Shortcuts and Accelerators
Shortcut keys:
key combinations to directly invoke a command
e.g. Control O to open a file
item.MenuItems.Add (new MenuItem ("&Open...", new EventHandler (OnFileOpen), Shortcut.CtrlO));
Keyboard Accelerators: to help accessing a menu item without using the mouse. An accelerator key related to a menu item is preceded with an “&” and is displayed underlined.
e.g. Alt F to access the File menus, then O to open a file
Microsoft defines Keyboard Accelerators the same as Shortcuts.

34. Drawing in .NET .NET Drawing Classes: in System.Drawing.
Graphics Device Interface (GDI) software to interface with the graphics hardware.
GDI+ Graphics Primitives (System.Drawing.Drawing2D): Bitmap, Font, HatchBrush, LinearGradientBrush, Pen, SolidBrush, TextureBrush, DrawArc, DrawCurve, DrawEllipse, DrawIcon, DrawImage, DrawLine, DrawPie, DrawPolygon, DrawString, FillEllipse, FillPie, FillPolygon, FillRectangle.

35. Drawing in .NET cont.
GDI+ : stateless, a form passes parameters detailing output characteristics to every Graphics method it calls. For (stateless) Internet use.
Old Windows GDI: stateful, drawing parameters are stored as state variables in the GDI’s device context.
Example: DialogDemo.cs – OnPaint(PaintEventArgs e)
Dispose your GDI+ Objects to avoid running out of GDI+ resourses. e.g. brush.Dispose();

36. GDI and Beyond DirectX: Direct3D, DirectMusic, DirectSound.
Xbox (based on DirectX): Video Game
XNA (Xbox New Architecture, XNA is Not an Acronym):
Video Game development and management
WPF: Windows Presentation Foundation
Introduced in .NET 3.0
Based on DirectX, not GDI
2D and 3D

37. Summary GUI-based windows application development:
GUI-based programming.
forms and controls,
look and feel
EDP
events and handlers
GDI