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Chapter 3. Building an Application in the Visual Basic .NET Environment. Making an Application – Interface Design. Once you have analyzed the problem and understand the needs, the next step is to design the user interface ( UI ).

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Chapter 3

Chapter 3

Building an Application in the Visual Basic .NET Environment


Making an application interface design
Making an Application –Interface Design

  • Once you have analyzed the problem and understand the needs, the next step is to design the user interface (UI).

  • The UI is the way the a program accepts data and instructions from the user and produces results.

  • A Graphical User Interface (GUI) provides visual cues such as a menu, a button, or small pictures (called icons) to help the user enter data and give instructions to the computer.


More new terms
MORE NEW TERMS

  • A control is said to have focus when it is selected on the screen.

  • Usually it’s easy to see which object has focus during a run. You’ll see the cursor blinking or a box around the button or control.

  • You can set the focus to any object via code or by setting properties.

  • Properties--characteristics, or attributes, of a control, such as its color or the text that displays on top of it.

  • Properties window -located on the right hand side of your screen. You go there to change properties during design time


Using the property window
Using the Property Window

  • Object Box – displays the name of the currently selected object or control.

  • Property List – displays the set of properties for the object named in the Object Box.

  • Toolbar

    • Categorized button – properties are grouped by categories such as behavior or appearance.

    • Alphabetic button – all the properties are displayed alphabetically.

  • Description Pane – displays information about what the selected property is for.

  • It is not necessary to set every property for controls added to your forms. VB.Net assigns default values for each property.


New properties form
NEW PROPERTIES -- FORM

  • StartPosition Property (form)– specifies the position where the application will display on run.

    • The default value is WindowsDefault.

    • Please switch to CenterScreen for my applications.

  • Text Property (form)– allows you to set the title for a form.

  • FormBorderStyle Property – controls the appearance of the border of a form.

    • Default value is Sizable. User can drag and resize the application at run.

    • Please switch to FixedDialog for my applications.

  • BackColor and ForeColor – sets the background and foreground colors for the form.


New terms
NEW TERMS

  • Design time - the time during which you build an application.

  • Run Time-- the time during which you use a program for its intended purpose.

  • Controls-- objects that you can add to your form.They are found on VB.Net’s Toolbox

    • Label control -- displays text on the form that cannot be altered by the end user.

    • Textbox control--displays text on the form that can be altered by end user

    • Button control--used by the user to initiate actions called events.

    • NumericUpDown control – used to display or allow users to enter numbers on a form. Cuts down on user’s ability to screw things up.


Some important properties
SOME IMPORTANT PROPERTIES

  • Name-- allows you to rename the object to something that makes more sense.

  • Text- allows you to change the words that show up on the control itself. (or on the title bar of the form!).

  • Read-Only--Makes it impossible for the end user to edit the text in that box.

  • Tab Index--Allows the programmer to control the order in which the control gets the focus when the user is tabbing

  • Tab Stop--Allows the programmer to have a control skipped during tabbing.

  • Font--Allows the programmer to change the style of the captions and text.


More important properties
MORE IMPORTANT PROPERTIES

NUMERIC UP/DOWN BOXES

  • Value Property – (NUD) defines the current value displayed in the control

  • Minimum and Maximum Properties – (NUD) allows the programmer to define the upper and lower boundaries for the values in a NUD control.

  • Decimal Places Property – (NUD) allows the programmer to set up the number of decimal points allowed in the control. Default is 0.


Comment statments
COMMENT STATMENTS

  • COMMENT STATEMENTS – programmers often add comments within their code as a form of internal documentation.

    • A comment is text added within an event procedure that explains how the code works or why it is written.

    • Comments are not executed by the computer and are ignored by .NET

    • Comments are included for informational purposes and for other programmers. They are an excellent means for team’s of programmers to communicate with one another.

    • They also are a great way for you to leave notes to yourself or others.

  • Each comment line must begin with an apostrophe or the letters REM – which is short for “remark”.



Naming controls
NAMING CONTROLS

  • We learned four new controls this chapter.

  • Any of these objects that are receiving code must be renamed with one of the following prefixes:

    • TXT= Text box

    • BTN = Button

    • LBL = Label

    • NUD = Numeric Up/Down


Events
EVENTS

  • Most windows applications are event-driven programs.

  • Events are messages sent to an object

    • Click event – default event for buttons. Code will execute when user Clicks on the button.

  • Event procedures, which are triggered by events, are groups of code statements

  • Code statements are instructions to the computer written at design time for the computer to execute at run time


Writing code in the code window
Writing Code in the Code Window

  • Intellisense anticipates your needs during coding and displays prompts to assist you in coding

  • A syntax error is an error caused by code statements that violate one of the structure or syntax rules of the Visual Basic .NET language

  • Event procedures for controls start with the word Private Sub since the section is just for that one control.

  • The line that begins End Sub indicates the end of a particular event procedure.


Assignment statements
Assignment Statements

  • controlname.propertyname=propertyvalue



Chapter 3 complete

Chapter 3 Complete

Building an Application in the Visual Basic .NET Environment


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