Key Related Events in C# .Net

 

Key Related Events

1. KeyPress
2. Key down
3. Key Up

 The difference between Keypress and Key down:

• In key press, logic will be executed Before displaying a character
• In key down, logic will be executed After displaying a character
• Key board character are divided into two types:-

   

 

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Example of developing a Ball and Bat game:

   

• Open WFAP
• Place a Label control  properties 

Back  Color = black Auto Size  = false Location  = 202, 440 Left,    top

• Place a Picture Box Control  Properties 

Image = Select an image Size mode  = Stretch image Location  = 13, 200 Left,    top

• Place a Timer with Enabled = true;
• Place one more Timer with Enabled = false
• Code for Form1_Keydown event

{

Int I = (int) e.  keycode;

//Message Box. Show (I + “”);

If ((I = = 37)  && Label1.left > 0 )

Label 1.left = Label1.left -3;

If ((I = = 39)  && Label1.left < this. Width - 100 )

Label 1.left = Label1.left +3;

}

• Code for Timer 1 _ Tick Event

{

Picture Box. Top = Picture Box 1. Top – 15;

If (Picture Box. Top  < 0)

{

Timer 1. Enabled = false;

Timer 1. Enabled = true;

}

Code for Timer 2 _ Tick Event

{

Picture Box1. Top = Picture Box 1. Top +5;

Picture Box2. Left = Picture Box 1. Left +1;

If  (Picture Box1. Top = Label1.Top && Picture Box1.left  >Label1.left && Picture Box1. Left  < Label1.right )

{

Timer 1.enabled = true;

Timer 2.enabled = false;

}

     

2.Every item will be identified with a unique index number which tarts always from zero.  

 

3. Como box allows to select only one item at a time
4. The list box allows to select multiple items also.

 

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Common Properties and methods of list box and combo box:- 

Properties:-  

1. Items used to add items at design time
2. Selected item
3. Selected Index

  Methods: -

   

1. Combo box1. Items Add (String)
2. Combo box1. Items Insert(index, String)
3. Combo box1. Items Remove(String)
4. Combo box1. Items Remove(index)
5. Combo box1. Items clear();
6. Combo box1. Items Index of (String)
7. Combo box1. Items Countà(property)
8. Combo box1. Items Get Enumerator ();  

 Example on combo box:-

A program to change the shape of  a FORM

   

Namespace System Drawing. Drawing 2 D

• Open WFAP
• Place a combo box properties  Items = add

 

• Using System . Drawing . Drawing 2 D;
• Code for combo box 1 _ Selected Index changed Event

  Graphics path g = new Graphics path ();

Int I = combo box 1. Selected index;

If  (I = = 0) //circle

1. Add Ellipse (10, 10, 150, 150) ;

else if (i ==1 ) //ellipse

1. Add Ellipse (10, 10, 150, 400) ;

else //triangle {

1. Add Line (10, 10, 200, 300) ;
2. Add Line (200, 300, 100, 150) ;
3. Add Line (100, 150, 10,10) ;

}