1. CSC 298
Windows Forms

2. Programming Windows Forms
Use the FCL classes in the namespace System.Windows.Forms, e.g.
Form: most Windows Forms applications derive from Form
Application: the Run method provides the message loop to handle the interaction of the user with the Form
Use also the classes in System.Drawing for graphics capabilities (Graphics Device Interface+ GDI+), e.g. the Graphics class.

3. Inheritance hierarchy of Form

4. Using Forms Know about common structs
Color (create your color with FromArgb)
Rectangle: upper left point (x,y), width, height
Size: width and height
Point: (x,y)
Know about the common form properties
ForeColor, BackColor, Font, ClientRectangle,
Practice: see class website

5. Forms and events Input model for forms is event driven
any action on the form by the user (mouse click, key pressed, etc…) is associated with a different method in a class
the user's action triggers a call to the method
To manage the user's actions, override these methods in the class that inherits Form
Common methods
OnMouseDown, OnMouseUp, OnMouseMove, OnPaint, etc…

6. Event Methods To override, write e.g. for OnPaint
protected override void OnPaint(PaintEventArgs pea) { /* your code */ }
All event methods take an argument that describe the event, for instance
MouseEventArgs for mouse events
KeyEventArgs, KeyPressEventArgs for keyboard event
EventArgs for events that don't carry a particular description (resize event, change of the backcolor, etc…)

7. Alternative: create an event handler
Create an event handler and attach it to the relevant event, e.g.
public class MyForm: Form{ {
public MyForm(){
PaintEventHandler myHandler = new PaintEventHandler(MyOnPaint); this.Paint += myHandler;
// rest of the constructor }
private void MyOnPaint(Object source, PaintEventArgs pea) {/* code */}

8. Delegates
Event handlers must match a method prototype called the delegate, defined as for instance
public delegate void PaintEventHandler(Object source, PaintEventArgs pea);
Common event handlers
KeyEventHandler, MouseEventHandler, EventHandler
Common events on a form (look for )
mouse: Click, MouseMove, MouseUp, MouseDown, etc…
keyboard: KeyDown, KeyUp, KeyPress
others: Resize, Closing, etc…

9. Controls on a form
A form is a container. Thus it can have controls, e.g. buttons, radio buttons, check boxes…
Can't override the protected event methods for these controls since their classes are not inherited
Must use the event handler approach
public class MyForm: Form{
private Button cmdOK = new Button();
public MyForm(){
cmdOK.Click += new EventHandler(CmdOnClick); }
private void CmdOnClick(Object source, EventArgs ea){ /* code for click on OK button */ }

10. Defining your own events
Rarely needed for common applications
Create your own delegate to define the prototype of the event handler
public delegate void MyEventHandler(Object source, MyEventArgs mea);
Create a variable of the type defined by the delegate: the event
public event MyEventHandler MyEvent;
The user of the class adds (+=) or removes (-=) event handlers to the event
See example (Phone.cs)