© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 1 Unit 1 Introduction to Programming Using VB.NET Chapter 2 Creating Applications with VB.NET

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 2 A First Visual Basic.NET Application Develop your first application:  Display a map and written directions to the Highlander Hotel  Use a form with labels  Use a PictureBox control  Write an event procedure

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 3 Focus on Problem Solving: Building the Hotel Directions Application In This Section You Create Your First Visual Basic.NET Application: a Window That Displays a Map and Road Directions to a Hotel

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 4 Clearly Define What the Program is To Do Purpose: Display a map to the Highlander Hotel Input: None Process: Display a form Output: Display a graphic image showing a map on the form

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 5 Visualize the Application Running on the Computer and Design its User Interface

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 6 Make a List of the Controls Needed Control TypeDescription (Control Name) FormA small form that will serve as (Default Name: Form1)the window onto which the other controls will be placed LabelDisplays the message (Default Name: Label1) "Directions to the Highlander Hotel" PictureBoxDisplays the graphic image (Default Name: PictureBox1)showing the map to the hotel

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 7 Define the Values of Each Control's Relevant Properties Form  Name: Form1  Text: "Directions" Label  Name: Label1  Text: "Directions to the Highlander Hotel"  TextAlign: MiddleCenter  Font: Microsoft sans serif, bold, 18 point PictureBox  Name: PictureBox1  Picture: HotelMap.jpg  SizeMode: StretchImage

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 8 Use Visual Basic.NET to Create the Forms and Other Controls Establish the Form Add the Labels Set the TextAlign Property, Font and Style Insert a PictureBox Control Try Running the Application

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 9 Project Organization on Disk Each Solution is stored as a Visual Basic.NET Project Within the Folder created with the project name are various files, including: .sln contains data describing the solution .vbproj contains data describing the project

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 10 Properties Window Used to view and modify the property values of a given object Two views of the properties:  Alphabetic (across all properties)  Categorized (groups properties by logical use)

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 11 Focus on Problem Solving: Responding to Events An Application Responds to Events, Such As Mouse Clicks and Keyboard Input, by Executing Code Known As Event Procedures In This Section, You Write Event Procedures for the Directions Application

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 12 Augment the Hotel Application Now the hotel owner wants to add an option to view written directions:

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 13 Controls to be Added Control TypeDescription (Control Name) LabelDisplays written directions to (lblDirections)the hotel ButtonWhen clicked, causes the above (btnDisplayDirections) label to appear on the form ButtonStops the application (btnExit)when clicked

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 14 Direction's Application Control Properties Label:  Name: lblDirections  Text: "Traveling …" Button  Name: btnDisplayDirections  Text: "Display Directions" Button:  Name: btnExit  Text: "Exit"

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 15 Method btnDisplayDirections_Click, I Private Sub btnDisplayDirections_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles btnDisplayDirections.Click ' Make the directions visible lblDirections.Visible = True End Sub Line Continuation Mark Name of the event the procedure responds to Name of the control that owns the event procedure Marks the beginning of this event procedure

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 16 Method btnDisplayDirections_Click, II Private Sub btnDisplayDirections_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles btnDisplayDirections.Click ' Make the directions visible lblDirections.Visible = True End Sub Makes the control lblDirections visible: Assigns the value True to the Visible Property of the lblDirections control.

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 17 Syntax for Referring to the Value of a Control's Property ControlName Dot PropertyName In this situation:  lblDirections.Visible

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 18 Syntax for an Assignment Statement Item receiving the value Equal symbol Value to be assigned In this situation:  lblDirections.Visible = True

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 19 Use Visual Basic.NET to Update the Application Place the label and the buttons on the form Enter the code for the two procedures Test the application

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 20 Additional Properties Color properties:  BackColor: Sets the background color  ForeColor: Sets the foreground (e.g., text) color Form style property value examples:  Sizable: (Default) Has normal buttons in upper right and is resizable via the edges  Fixed3D: Has a 3D look; normal buttons; is not resizable by its edges

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 21 Modifying the Text Property With Code Quite Often, You Will Need to Change a Control’s Text Property With Code This Is Done With an Assignment Statement

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 22 The Text Property Can Be Modified via Code, I Suppose that a form was established with a label lblMessage that said: 1 Kilometer = ? And on a btnfeet button click, we wanted to change the value of the text property to 1 Kilometer = 3,281 feet

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 23 The Text Property Can Be Modified via Code, II Private Sub btnFeet_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles btnFeet.Click ' Display the conversion to feet. lblMessage.Text = "1 Kilometer = 3,281 feet" End Sub Assigns the given string to the text property of lblMessage This has the effect of changing the previously displayed value to this one

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 24 The AutoSize, BorderStyle, and TextAlign Properties The Label Control’s AutoSize Property Allows a Label to Change Size Automatically to Accommodate the Amount of Text in Its Text Property The BorderStyle Property Allows You to Set a Border Around a Label Control

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 25 AutoSize Property for Labels AutoSize is a Boolean (True or False) Property of labels False (the default) means that the box size will not change, depending on the amount of text assigned to it True means that it will resize itself to fit variable amounts of text

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 26 BorderStyle Property for Labels BorderStyle determines the look of the box  None (the default) means no border  FixedSingle means a border one pixel wide  Fixed3D gives it a recessed 3-dimensional look

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 27 TextAlign Property for Labels The value of TextAlign establishes the text's justification:  TopLeft  TopCenter  TopRight  MiddleLeft  MiddleCenter –MiddleRight –BottomLeft –BottomCenter –BottomRight

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 28 Clickable Images Controls Other Than Buttons Have Click Event Procedures

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 29 PictureBox Control As we saw earlier the Image Property can be set to an graphic of some sort The image is clickable This event can be handled by code to take whatever the appropriate action is

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 30 PictureBox Click Event code When PictureBox picUSA is clicked, lblMessage is set appropriately: Private Sub picUSA_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles picUSA.Click ' Display the country name lblMessage.Text = "United States of America" End Sub

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 31 Using Visual Basic.NET Help In This Section You Learn to Use the Visual Basic.NET Help System

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 32 Dynamic Help Dynamic Help provides help information that is relevant to the operation you are currently performing This window occupies the same location as the Properties window Simply select the tab at the bottom to select which you wish to view

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 33 Help Menu The usual categories of Help that you are probably accustomed to in Microsoft applications  Contents…  Index…  Search… Are available through this window also

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 34 Debugging Your Application At Some Point, Most Applications Contain Bugs, or Errors That Prevent the Application From Operating Properly

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 35 Types of Errors: Compile Errors These are errors in the syntax (form) of your program Visual Basic.NET will inform you of these as soon as they are found The area of the error will be shown with a jagged blue line A description of the error will be given in the Task List window

© 2006 ITT Educational Services Inc. Introduction to Computer Programming: Unit 1: Chapter 2: Slide 36 Types of Errors: Runtime Errors These errors occur while your program is running Visual Basic.NET will detect some of these and inform you about them Others you must detect yourself Always carefully check the operation of your program to be sure that it operates as required