1. Chapter 1: An Introduction to Visual Basic 2015

2. Lesson B Objectives After studying Lesson B, you should be able to:
Add a control to a form
Set the properties of a label, picture box, and button control
Select multiple controls
Change the layering order of controls
Center controls on the form
Open the Project Designer window
Start and end an application
Enter code in the Code Editor window
Terminate an application using the Me.Close() instruction
Run the project’s executable file
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3. Wndows In lesson 1A you have learned about:
Windows Form Designer
Solution Explorer Window
Properties Window
In this lesson you will learn about the Toolbox window (also known as toolbox)
The toolbox contains the tools you will use to create your application’s user interface
Each tool represents a class from which an object such as a button or textbox can be instantiated
Instantiated objects called controls will appear on the form
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4. The Toolbox Window Class Object Toolbox window (or toolbox) Controls
A pattern from which an object is created
Object
An instance with behaviors and attributes
Toolbox window (or toolbox)
Contains tools for designing a user interface
Each tool represents a class
Controls are instantiated using tools from the toolbox
Controls
GUI objects that appear on a form
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5. The Toolbox Window (cont.)
Figure 1-13 Toolbox window showing the purpose of the Label tool
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6. The Label Tool (p29)
Use the Label tool to add a label control to a form
A label control displays text that cannot be edited at run time (it means that the user is not allowed to modify)
Notice that
Appears in the Object box in the properties window
Label1 is the
Label1 is the default name assigned to the label control
System.Windows.Forms.Label indicates that the control is an instance of the Label class
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7. The Label Tool (p29) Name property (p30) Text property (p31)
A unique name for a control
Text property (p31)
Specifies the value that appears in a label control
Location property (p31)
Specifies the location of a control on a form
Includes an X value and a Y value
How do you select a control on the form without clicking on it?
Your answer is: ?
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8. Figure 1-15 Label control added to the form
The Label Tool (cont.)
Figure 1-15 Label control added to the form
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9. The Label Tool (cont.) Setting the Text Property
Select the lblMsg control
Click text in the Properties list
Type Come visit our residents!
Press Enter
Verify that the AutoSize property is set to True
Select the lblName control
Type Crighton Zoo
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10. The Label Tool (cont.) Setting the Location Property
Select the lblMsg control
Click Location in the Properties list
Expand the Location property by clicking the plus box
Type 180, 115
Press Enter
Select the lblName control
Type 180, 70
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11. Changing a Property For Multiple Controls (p31)
A control inherits the font attribute of the form
Sometimes You may want to use different font type, style, or size for a control text
You can change the font, the size o other property of one control (or more than one control of the same class)
In the Splash screen You can make the text in the two label controls more noticeable by increasing the size of the font used to display text (p31)
Select the first control, hold down the Ctrl (Control) key as you select the other control (or controls) on the form
Figure 1-16 Label controls selected on the form
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12. Changing a Property For Multiple Controls (p31)
A control inherits the font attribute of the form
Sometimes You may want to change the default values
To simultaneously modify similar controls:
Click one control and then press and hold the Ctrl key
Click other similar control(s) in the form, or click and drag to group the controls
Set the property value in the Properties list
Figure 1-16 Label controls selected on the form
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13. Changing a Property For Multiple Controls (cont.)
Using the Format Window’s Order Option (p32)
The Format menu contains an Order option that allows you to control the layering of one or more controls on a form
Using the Format Menu’s Order Option (p32)
Change the form’s Backcolor property to dark green
Add… 3…
Figure 1-17 New label on top of previous labels
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14. Changing a Property For Multiple Controls (cont.)
Using the Format Window’s Order Option (p32)
To layer one control over another layer
Create a label control and size it to cover other labels
Figure 1-17 New label on top of previous labels
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15. Changing a Property For Multiple Controls (cont.)
Using the Format Window’s Order Option (p33)
To reverse the layers
Click the label control on the form
Click Format on the menu bar
Point to Order and then click Send to Back
Figure 1-17 New label on top of previous labels
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16. The PictureBox Tool (p33)
You can include an image on a form using a picture box control which you instantiate using the picture box control
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17. The PictureBox Tool (p33)
Creates a picture box control
Displays an image on a form
Task box: Lists tasks associated with a picture box
Use the task box to import an image into a project
A project’s resource file contains imported images
Figure 1-19 Open task list for a picture box
Figure 1-20 Completed Select Resource dialog box
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18. The PictureBox Tool (cont.)
Figure 1-21 Picture boxes added to the form
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19. The PictureBox Tool (cont.)
Using the Format Menu to Align and Size (p35)
The Format menu provides a Center in Form options for centering one or more controls either vertically or horizontally on the form
The Format menu also provides an align option for aligning two or more controls by their left, right, top, or bottom borders
The menu Make Same Size option allows to make to or more two or more controls the same width and/or height
Before you can use the Format menu to change the alignment or size of two or more controls, you must first select the controls
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20. The PictureBox Tool (cont.)
Select the reference control first . The reference control is the one whose size and/or location you want to match
The reference control will have white sizing handles,
Whereas the other selected controls will have black sizing handles
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21. The Button Tool (p36)
Every application should give the user a way to exit a program
Most Windows applications accomplish the task by using either an exit option on the File menu or an exit button
In this lesson the splash screen will provide a button for ending the application
In Windows applications a button control is commonly used to perform an immediate action when clicked
The OK and Cancel button are examples of button controls found in many Windows applications.
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22. The Button Tool Used to create a button control
Used to perform an action when clicked
Examples: OK and Cancel buttons
Common means of exiting a Windows application:
Exit option on the FILE menu
Exit button
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23. The Button Tool Steps to add a Button control to the form (p36)
Use the button tool in the toolbox
The three-character ID used when naming button control is btn
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24. Starting and Ending an Application
Startup form
Displays when an application is first started
The Project Designer window specifies the startup form or the executable code to be run
Right-click My Project in the Solution Explorer window and then click Open
Or, click PROJECT on the menu bar and then click <project name> Properties
Application tab
Specify startup form
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25. Programming with Microsoft Visual Basic 2015

26. Starting and Ending an Application (cont.)
Executable file
A file that can be run outside of the IDE
Its filename ends with .exe
It is automatically created when a Visual Basic application is started
Two ways to start an application in the IDE:
Click DEBUG on the menu bar and then click Start Debugging
Press the F5 key
Figure 1-22 Application pane in the Project Designer window
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27. The Code Editor Window (p 39)
After creating your application interface, you can begin entering the Visual Basic instructions (code) that tells the controls how to respond to the user’s actions
Those actions such as clicking, double-clicking, and scrolling are called events
You tell an object how to respond to an event by writing an event procedure which is a set of Visual Basic instructions that are processed only when the event occurs.
You enter the procedure’s code in the Code Editor window.
In this lesson you will write a Click event procedure for the Exit button which should end the application when it is clicked
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28. The Code Editor Window Events Event procedure Code Editor window
User actions such as double-clicking
Event procedure
A set of program instructions that are processed when an event occurs
Code Editor window
Provides templates for creating event procedures
To open it, right-click the form and then click View Code
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29. The Code Editor Window (cont.)
Figure 1-24 Code Editor window opened in the IDE
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30. The Code Editor Window (p39)
Figure 1-26 was obtained using Visual Studio lets use this figure to illustrate the paragraph at the bottom of page 39
Project list box
Object list box
Method list box
This Code Editor window contains three (the Visual Studio 2013 provides only two) dropdown list boxes
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31. The Code Editor Window (cont.)
Dropdown list boxes named:
Project
Object
Method
T he project box contains the name of the current project: Splash Project
The object box lists the names of the objects included in the user interface
The method box lists the events to which the selected object is capable of responding
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32. The Code Editor Window (cont.)
In object-oriented programming (OOP), an event is considered a behavior of an object because it represents an action to which the object can respond
In (OOP), the Code Editor window “exposes” an object’s behavior to the programmer
You use the Object and Method list boxes to select the object and event, respectively, that you want to code
In this case you will select btnExit in the Object list box, and you will select Click in the Method list box
This is because you want the application to end when the Exit button is clicked
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33. The Code Editor Window (p 40 cont.)
To select the btnExit control’s Click event (p40):
1. Click the object list arrow and then click btnExit in the list Click the Method list arrow and then click and then click Click in the list…. A code template for the btnExit control’s click event procedure appears in the Code Editor window (see Figure 1-26)
Figure 1-26 btnExit control’s Click event procedure
The code editor provides the code template to help you follow the rules of the Visual Basic language
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34. The Code Editor Window (p 40 cont.)
Syntax: The rules of a programming language are called its syntax
OOP: Object-oriented programming; events are clickable
Procedure header: The first line in the code template for an event procedure
Procedure footer: The last line in the code template for an event procedure
Keyword: A word that has a special meaning in a programming language
Keywords appear in different color than the rest of the code
The Private keyword in Figure 1-26 indicates that the button’s Click event procedure can be used only within the current Code Editor window
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35. The Code Editor Window (p 40 cont.)
Keyword: A word that has a special meaning in a programming language
Keywords appear in different color than the rest of the code
The Private keyword in Figure 1-26 indicates that the button’s Click event procedure can be used only within the current Code Editor window
The Sub keyword is an abbreviation of the term sub procedure, which is a block of code that performs a specific task
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36. The Code Editor Window (cont.)
Sub procedure
A block of code that performs a specific task
Keywords in a sub procedure block:
Sub: Starts a sub procedure
Private: Restricts the use of the procedure to the form where it appears
End Sub: Indicates the end of a sub procedure
Event sub procedure names include the object name and event name
Example: btnExit.Click
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37. The Code Editor Window (p 40 cont.)
With Visual Studio 2013 you have this Code Editor window
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38. The Code Editor Window (cont.)
OOP
Object-oriented programming; events are clickable
Syntax
The rules of a programming language
Procedure header
The first line in the code template for an event procedure
Prcoedure footer
The last line in the code template for an event procedure
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39. The Code Editor Window (cont.)
The Me.Close() Instruction
Method
A predefined procedure
Can be called (or invoked) when needed
Me.Close() method
Causes the current form to close
If it is the only form in an application, the application terminates
IntelliSense feature
Provides appropriate selections as pop-up lists
Type the first few letters of your choice
Then use the arrow keys to select an item in the list
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40. The Code Editor Window (cont.)
Figure 1-27 List displayed by the IntelliSense feature
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41. Lesson B Summary
To add a control to a form, use a tool from the toolbox
Use the label control for text that users cannot edit
You can set the properties of multiple controls simultaneously
To start and stop an application in the IDE, use DEBUG on the menu bar
Use the Code Editor window to display an object’s event procedures
The Me.Close() method closes the current form at run time
Programming with Microsoft Visual Basic 2015