Basic Controls

1
Basic Controls Properties
Chapter 2
2
Overview

• VB-IDE
• Basic Controls
• Command Button
• Label
• Text Box
• Picture Box
• Program Editor
• Setting Properties with Code

3
The Visual Basic IDE
4
The Workspace Toolbox
5
Selecting Tools

• Using the toolbox and the Workspace Window you
  can build a form that has nearly any desired
  appearance
• Double click on an icon in the toolbox to create
  a new instance of that type of object in your
  workspace
• These objects are called controls
• Using the mouse, a control can be resized or moved

6
The Project Window

• This window allows you to select and open one or
  more forms that are used in a given project.

7
The Form Layout Window

• You may use this window to adjust the position of
  the form on the CRT screen.
• Clicking on the X will close this window and
  leave room for other things.

8
The Properties Window

• This window allows you to examine and modify the
  various properties of control objects in a
  program
• Properties govern the appearance and behavior of
  a control object
• They may be modified using the properties window,
  or by VB code

9
The Command Control

• The command control is one of the most important
  tools in the toolbox
• Double clicking on the command button icon will
  install a command button on the working form

Command Button
10
Adding a Command Button

• The command buttons are named, by default
  Command1, Command2, etc.
• They may be moved or changed in size using the
  mouse

11
Properties of Command Buttons

• Each command button has several properties.
  govern the buttons appearance and behavior
• The most important are the (name) and the caption
• (name) is how a programmer can refer to the
  button in VB code
• caption is the text a user will see displayed
  inside the button

12
Highlighting a Property

• When you highlight a property, its definition
  appears below the properties window

13
Names and Captions

• Clicking on the (name) property lets us name it
  cmdstop, (note the name starts with cmd)
• Changing the caption to Stop gives the user an
  idea as to the buttons function

14
Naming Convention

• Good practice in Visual Basic suggests that we
  should name all objects in a program with names
  that indicate their function
• These names are invariant during a programs
  execution and are seen only by programmers
• Command buttons names should begin with the
  prefix cmd
• Names should begin with the prefix for the given
  object type, and should contain only letters and
  numbers
• Captions are used to convey information to the
  user
• They can change as the program runs
• They may contain any letters, numbers, spaces,
  etc.

15
Command Buttons The Program Editor

• Visual Basic (VB) supports a text editor (not a
  word processor) that permits the writing and
  modification of program code
• The program editor is one of two sub-windows that
  appears in the Workspace
• The other is the Forms window
• Many of the commands used in the program editor
  are like those used in word processors, but there
  are differences

16
Entering the Editor

• The editor is normally entered by double
  clicking on an Event Producing Object in the
  workspace.
• The result is a code window which opens with the
  subroutine describing that event as the focus.

17
Entering Event Code

• Double clicking on the cmdStop button itself,
  causes the Code window to open
• The VB commands that define the buttons function
  go here
• The End command terminates the VB program

18
The Label Control

• The label control is an object with 37 named
  Properties
• You can adjust its size and position with the
  mouse
• You can change its (name) its caption and
  visibility using the Properties window

19
Label Control Properties
20
Using Labels

• The label control is usable only for output
• It cannot accept input from the user
• Its size, shape, color, visibility and the form
  of the information presented can be controlled
• By editing its properties
• By writing VB code to change its properties
• Labels can be sized and moved using the mouse.

21
A Program Using a Label
22
Using a Label

• When program execution begins, the system starts
  as in A, when the cmdby button is pressed the
  system goes to B
• Repeated pressing of the cmdby button bounces the
  system between the two states

23
Naming Convention

• Labels should be given a (name) that begins with
  lbl.
• The Caption property of a label may be anything
  that makes sense one or more words or symbols.
• Caption is displayed for the user
• (name) is only accessible to the programmer
• The Visible property may be either True or False
• If false, the label is not displayed

24
3. The Text Box Control

• Labels are designed to be used for output
• Command buttons can accept input from the user,
  but only of a limited nature
• The text box control allows the user input data

25
Text Box Properties

• The text property contains the string of text
  displayed by the text box
• Unlike labels, by default this text can be edited
  by the user at runtime
• The proper prefix for text box names is txt
• Text boxes do not have Caption property!

26
4. The Picture Box

• The Picture box control can be used to display a
  picture on the form
• The proper prefix for picture box names is pct
• Click on its Picture property
• A command button with an ellipsis () will be
  displayed
• By clicking on the button, a dialog box will
  appear to select the graphic file to display
  within the picture box control