common controls

The Text Box
The text box is the standard control for accepting input from the user as well as to display the output. It can handle string (text) and numeric data but not images or pictures. String in a text box can be converted to a numeric data by using the function Val(text). The following example illustrates a simple program that processes the input from the user.
The Label
The label is a very useful control for Visual Basic, as it is not only used to provide instructions and guides to the users, it can also be used to display outputs. One of its most important properties is Caption. Using the syntax label.Caption, it can display text and numeric data . You can change its caption in the properties window and also at runtime.
The Command Button
The command button is one of the most important controls as it is used to execute commands. It displays an illusion that the button is pressed when the user click on it. The most common event associated with the command button is the Click event.
The Picture Box
The Picture Box is one of the controls that is used to handle graphics. You can load a picture at design phase by clicking on the picture item in the properties window and select the picture from the selected folder. You can also load the picture at runtime using the LoadPicture method. For example, the statement will load the picture grape.gif into the picture box.

Picture1.Picture=LoadPicture ("C:\Images\1.gif")

You will learn more about the picture box in future lessons. The image in the picture box is not resizable.

The List Box
The function of the List Box is to present a list of items where the user can click and select the items from the list. In order to add items to the list, we can use the AddItem method. For example, if you wish to add a number of items to list box 1, you can key in the following statements

Example 3.2



Private Sub Form_Load ( )



List1.AddItem “Lesson1”

List1.AddItem “Lesson2”

List1.AddItem “Lesson3”

List1.AddItem “Lesson4”



End Sub

The items in the list box can be identified by the ListIndex property, the value of the ListIndex for the first item is 0, the second item has a ListIndex 1, and the second item has a ListIndex 2 and so on

The Combo Box
The function of the Combo Box is also to present a list of items where the user can click and select the items from the list. However, the user needs to click on the small arrowhead on the right of the combo box to see the items which are presented in a drop-down list. In order to add items to the list, you can also use the AddItem method. For example, if you wish to add a number of items to Combo box 1, you can key in the following statements

Example 3.3

Private Sub Form_Load ( )

Combo1.AddItem “Item1”

Combo1.AddItem “Item2”

Combo1.AddItem “Item3”

Combo1.AddItem “Item4”

End Sub

The Check Box The Check Box control lets the user selects or unselects an option. When the Check Box is checked, its value is set to 1 and when it is unchecked, the value is set to 0. You can include the statements Check1.Value=1 to mark the Check Box and Check1.Value=0 to unmark the Check Box, as well as use them to initiate certain actions. For example, the program will change the background color of the form to red when the check box is unchecked and it will change to blue when the check box is checked. You will learn about the conditional statement If….Then….Elesif in later lesson. VbRed and vbBlue are color constants and BackColor is the background color property of the form.

Example 3.4

Private Sub Command1_Click()

If Check1.Value = 1 And Check2.Value = 0 Then
MsgBox "Apple is selected"
ElseIf Check2.Value = 1 And Check1.Value = 0 Then
MsgBox "Orange is selected"
Else
MsgBox "All are selected"
End If

End Sub

The Option Box The Option Box control also lets the user selects one of the choices. However, two or more Option Boxes must work together because as one of the Option Boxes is selected, the other Option Boxes will be unselected. In fact, only one Option Box can be selected at one time. When an option box is selected, its value is set to “True” and when it is unselected; its value is set to “False”. In the following example, the shape control is placed in the form together with six Option Boxes. When the user clicks on different option boxes, different shapes will appear. The values of the shape control are 0, 1, and 2,3,4,5 which will make it appear as a rectangle, a square, an oval shape, a rounded rectangle and a rounded square respectively.

Example 3.5

Private Sub Option1_Click ( )

Shape1.Shape = 0

End Sub



Private Sub Option2_Click()

Shape1.Shape = 1

End Sub



Private Sub Option3_Click()

Shape1.Shape = 2

End Sub



Private Sub Option4_Click()

Shape1.Shape = 3

End Sub



Private Sub Option5_Click()

Shape1.Shape = 4

End Sub


Private Sub Option6_Click()

Shape1.Shape = 5

End Sub

All above controls are most use in application, but there is many more controls are very usefull, here i copies lesson from vbtutor.net for fast and easy to understand controls and properties.