Working with user Defined controls, Properties, events

Working with user Defined controls, user defined Properties and user defined events

EMS: Employee manager system

LMS: Library management system

1. When a predefined control is not providing users requirement, then user defined control need to be developed
2. To develop user defined controls, NET Introduced

“Windows forms control library project template”

3. User defined controls will be created in the format of DLL’S
4. User defined controls contains application Logic along with GUI.
5. User defined controls are reusable (write once ute many times)
6. The controls developed in c# can be used in vb also. But not in ASP.NET

IIS: Internet information service

ASPX: Afire server pages extension

7. User defined controls are Not. Self executable; there are form dependants.

1 Steps for developing user defined controls:

Step1

open windows forms control library project, then design the control as required and write the logic

Step2

Add an Jcon(optional),Build the project to get a DLL file.

Step3

open windows forms application project and add the DLL file into the Tool Box.

Obs:-

A new control will be added into the Tool Box

Step4

place a new control on the form add use it as per the requirement.

User defined control is a class, which must be inherited either from user control class or form any exiting control

Based on above statement, user defined controls are divided into two types

General UC                                     Inherited UC

User Control                                                      Text box

Text                                                                       Text

àWhen the base class name is user control, then it is called as “General User control”.

When the base class name is any existing control name like text box, button etc, then it is called as “Inherited” user control”. 

Developing login user control:

Open windows forms control Library project with project name login text.

(Out put file is login text.Dll)

Choose properties and set name = login (User defined control)

(This name will be displayed in the tool box after adding the control)

Lace two labels, two text boxes and a button as shown code for button1_click

If (text box1.text ==”teja”&&text box2. Text==”abc”)

Message box. show(“valid user”);

Else

Message box. show(“not a valid user”);

}

Adding an Icon

Viewà Solution ExplorerRt click on login text Add New item Bit map and provide the name as  login.bmp

Note:

user control name and BMP file names must be same.

Choose properties and ht width =16 and height=16

Design the bitmap as required

Choose the properties of login.bmp file and set build action= embedded resource.

Build the project(build menuà build solution)

OBS:

Login text.dll will be created under

F:/0194/ Login text/ Bin/debug folder

Open WFAP

Open tool boxàRt Click inside of tool boxàadd tapà gire the name hy controls

Open tool boxàRt Click inside of my controls tabàchoose itemsàbrowseàlogin text. Dll

(or)

Drag login text. Dll file into

Tool box  my control tab

Obs:-

A New control will be added with the name login

Place a login control on to the form

Obs:-

1. In above user control, two text boxes and two labels and a button controls are integrated together and a new control is formed with the name login
2. in general user control. Individual controls properties will not be inherited.

I.e, In above example it is not possible to change the text of labels, text boxes or button

3. Hence user defined propertied need to be developed

Working with user defined controls and user defined properties:-

A =10 Set                      Property

B=AGET

Property

1. A Collection of and get functions is called as “property”.
2. A property with get function is called as read – only property.
3. Syntax to write a property

Data type variable;

Public data type pName

{

Set

{

Variable = value;

}

Get

{

Return variable;

}

}

Example on user defined properties and user defined controls:

1. Q) Developing a scrollable user control with 30 Forms

1. Q) Developing a scrolling user control with Ltext, Lfont ,LB color and L Seep properties

Open windows forms control Library project with project name scrollable control

Place a label control.

Place a timer with enabled = true

Place one more timer with enabled= false .

Code for hmer1_tick

{

Label1.Top= Label1.Top-5;(It will scroll upwards)

If(Label1.Top<0)

{

timer 1.Enabled = false;

timer 2.Enabled = True;

}

}

àCode for timer2-Tick

{

Label1.Top=Label1.top+5);

If(Label1.top>350)

{

Timer1.enabled=true;

Timer2.enabled=false;

}

}

àcode in GD(Initialize component)

//LtextàLabel1.textàString

Public string L Text

{

Set{Label1.Text=value;}

Get{return Label1.Text;}

}

//LFontàLabel1.FontàFont

Public Font LFont

(or)

Public Font1 Font

{

Set{Label1.Font=value;}

Get{return Label1.Font;}

}

//LBcoloràLabel1.Back Coloràcolor

Public color LB color

{

Set{Label1.Back clor=value;}

Get{return Label1.back color;}

}

//LSpeedàTimer. Intervalàint

Public int LSpeed

{

Set

{

Timer1.Interval=value;

Timer2.Interval=value;

}

Get

{return timer1.interval;}

}

Build the project(Build menuàbuild solution)

Bs:-

Scrollable control.dll is created under

D:\c194\Scrollable control\Bin\Debug Folder

With a new control named “User control1”.

Open WFAP

àDrag scrollable control.DLL into tool boxàMy controls tab

àThen a new control with name user control 1 will be added into the tool box place this control on the form and check Ltext, Lfont, LB color and Lspeed properties.

Working with Inherited user controls

1. Inherited user control is required to add extra functionality for an existing control.
2. In the base class name is user control, then it is called as General user control
3. If the base class name is any existing control, then it is called as inherited user control.
4. In inherited user control, all the properties will be inherited from base control

IN UC

Text box-----40 properties

Text_______1 properties

41 properties

Genera LU Control

User control

Test

Test =” ABC”

Generally inherited user control’s class declaration will be as follows

Public partial class test: Text box

{

}

In inherited user controls only application logic allowed but placing some other controls are not allowed

Example on in H User control

Developing a user defined text box with a new property called as input type

If input type is A or a ,then text box need to accept only Alphabets

If input type is D or D, then text box need to be accept only digits.

 If input type is All then text box need to accept all characters.

open windows forms control library project with project name UDT.

Open code window by pressing f7(don’t double click on the form to open code window)

Change the class declaration as follows

Public partial class user defined control: Text box code in GD

String S =”ALL”;//This is the default value for input type property.

Public user control()

Public String Input type

{

Set{S=Value;}

Get{return S}

}

Code for user control – Key press Event

Private void user control – key press(--)

{

If(s==”A”// S ==”a”)

{

If(e.kdy char>=’A’&& e. key char=’Z’)

//e.key char>=’a’ && e. key char=’Z’)

1. Handled=false;

else

1. Handled =true;//this statement

Cancels the

Key stoke

}

If(S==”D”\\S==d)

{

If(e.key char>=’o’&& e.key char<=’9’)

1. Handled = false;

else

1. Handled = true;

}

Build the project(Build menuà Build solution)

Obs:-

UDT.DLL will be created under

E:\c194\UDT\bin\debug folder

Open windows forms application project

àDrag UDT.DLL into tool boxàMy controls tab, then a new control will be added with the name  user control

Design the form As shown

Execute the project and check either text boxes are accepting proper input or not.

Working with user controls and user defined events

 A call back procedure is also called user defined events

• When part of user controls logic and part of form’s logic need to be executed at one, shot, then user defined events are required.
• User defined events are also called as call back procedures.
• User defined events can be created with in 4 steps

Step1: Create a Delegate

Syntax:

Public delegate void delegate name(or) Dname()

Step2:- Create an event with the help of the delegate

Syntax

Public event D Nam Event name;

Step3 :Raise event or call the event

Syntax:

Erent name()

Step4: Define the event(Write the body)

Prirate void control name enent name()

{

Logic;

}

• Step1,2 and 3 will need to be followed while developing the control(windows forms control library project) These steps are followed by Microsoft
• Step4 need to be followed while using the control (windows forms application project)

Example on user defined event

open windows control library with project name UDE

Place button

Code in GD

Step1:

Public d delegate void D name();

Step2:

Public event D name Abc;

Code for Button1-click

Message box. show(“from uses control”)

Stpe3:

Abc();

Build the project(Build menuà build solution)

UDE.Dll will be crated under

E:\c194\UDE\bin\debug

àopen windows forms application project

• Drag UDE.DLL into tool boxàMy controls

Tabà place an added control on the form

(user control 1)

àCode for user control ABC event

Message Box. show(“from form”);

• Execute the project and click on the button, then two message boxes need to be displayed.