Events in C# .Net

Events

Action on control is called an “Event”.

In C #. Net, always events take two arguments

Always the first argument will be an object but the second argument type may vary from event to event. C #.net events are divided into 4 groups

Mouse Related events

Focus Related events

Drag Related events

Key Related events

Mouse Related Events

Click

Double click

Mouse up

Mouse Down

House leave

House enter

Mouse More

Mouse Mover: this event will be fired when the mouse pointer placed on the control for some time.

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A program to use the company logo as the mouse pointer

Open windows form Application Project

Place a picture Box control àproperties

Image = Select an Image.

Size  Mode = Stretch Image

Code for Form1 Mouse More Event

{

Picture Box 1. Location = new Point  (e. x, e. y);

Cursor . Hide ();

}

Developing Animated Text

Open Windows Forms Application Project

Form àProperties àBack color  = Black

Place a button

Place a Timer with Enabled = false

  Using System. Drawing.Drawing 2D   Code in GD

String S = “MICRO SOFT TECHNOLOGIES”

Font f = new  Font  (“Arial ”, 50);

Linear Gradient Brush  b = new   Linear  Gradient Brush   

(new point  (100, 100), new Point  (200, 300), color. Red, color .yellow );

Int x =5; Graphics g;

// abstract class

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  Code for Button 1_ click

{

g = this .create Graphics ();

Draw String (S, f,b 10,10);

Timer 1. Enabled = true;

}

  Code for Timer 1_Tick event

{

X = X+3;

If (X > 300) X= 0;  

Linear Gradient Brush   b1 = new  Linear  Gradient Brush    

(new point  (100, 100), new Point  (x, 300), color. Red, color .yellow );

);

draw String (S, f,b, 10, 10);

Focus Related Events

Leave: This event will be executed while the cursor is coming out from control.

Enter: This event will be executed while the cursor is Entering into control.

Note:- Generally these events will be used in Data Validations  

Example on Leave Event 

Open Windows Forms Application Project

Place two Labels and two text boxes as shown

Place error Provider control àProperties àBack Style = Always Blink

Code for Text Box1 Leave Event {

If (text Box1. Text = “”)

Error Provider1. Set Error (text Box 1,” Eno should not be Empty “);

Else Error Provider1. Set Error (text Box 1,” “ .);

// No Space

}

Observations

Error Provider1. Set Error () takes two arguments

Arg 1: The control Name, after which a blinking  Icon needs to be displayed.

Arg 2: Error Message, if this is empty, then blinking  Icon will Will not be displayed.  

Drag Related Events

C # supports four Types of Drag Related Events

To work with Drag Related Events, ALLOW DROP property must be set to true.

Example: -

A program for dragging the data from MS – word into .net text box.

Open WFAP Place a text box - - >  properties - - >  Allow drop = true Multiline = true scroll bars = both

Code for Text Box 1 Drag Enter Event

{

If  (e. data. Get data present  (Data Formats .Text)  == true)

  {

String s = (String) . e. Data . Get Data (Data Formats. Text) ;

Text Box 1.Text = s;

}

else

Message Box. Show (“Not valid”);