1. Starting Out with Visual Basic.NET 2 nd Edition Chapter 2 Creating Applications With Visual Basic.NET

2. Starting Out with Visual Basic.NET 2 nd Edition 2.1 Introduction

3. Starting Out with Visual Basic.NET 2 nd Edition 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

4. Starting Out with Visual Basic.NET 2 nd Edition 2.2 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

5. Starting Out with Visual Basic.NET 2 nd Edition 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

6. Starting Out with Visual Basic.NET 2 nd Edition Visualize the Application Running on the Computer and Design its User Interface

7. Starting Out with Visual Basic.NET 2 nd Edition 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

8. Starting Out with Visual Basic.NET 2 nd Edition 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

9. Starting Out with Visual Basic.NET 2 nd Edition 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

10. Starting Out with Visual Basic.NET 2 nd Edition 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

11. Starting Out with Visual Basic.NET 2 nd Edition 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)

12. Starting Out with Visual Basic.NET 2 nd Edition 2.3 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

13. Starting Out with Visual Basic.NET 2 nd Edition Augment the Hotel Application Now the hotel owner wants to add an option to view written directions:

14. Starting Out with Visual Basic.NET 2 nd Edition 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

15. Starting Out with Visual Basic.NET 2 nd Edition Direction's Application Control Properties Label: Name: lblDirections Text: "Traveling …" Button Name: btnDisplayDirections Text: "Display Directions" Button: Name: btnExit Text: "Exit"

16. Starting Out with Visual Basic.NET 2 nd Edition 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

17. Starting Out with Visual Basic.NET 2 nd Edition 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.

18. Starting Out with Visual Basic.NET 2 nd Edition Syntax for Referring to the Value of a Control's Property ControlName Dot PropertyName In this situation: lblDirections.Visible

19. Starting Out with Visual Basic.NET 2 nd Edition Syntax for an Assignment Statement Item receiving the value Equal symbol Value to be assigned In this situation: lblDirections.Visible = True

20. Starting Out with Visual Basic.NET 2 nd Edition 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

21. Starting Out with Visual Basic.NET 2 nd Edition 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

22. Starting Out with Visual Basic.NET 2 nd Edition 2.4 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

23. Starting Out with Visual Basic.NET 2 nd Edition 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

24. Starting Out with Visual Basic.NET 2 nd Edition 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

25. Starting Out with Visual Basic.NET 2 nd Edition 2.5 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

26. Starting Out with Visual Basic.NET 2 nd Edition 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

27. Starting Out with Visual Basic.NET 2 nd Edition 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

28. Starting Out with Visual Basic.NET 2 nd Edition TextAlign Property for Labels The value of TextAlign establishes the text's justification: TopLeft TopCenter TopRight MiddleLeft MiddleCenter –MiddleRight –BottomLeft –BottomCenter –BottomRight

29. Starting Out with Visual Basic.NET 2 nd Edition 2.6 Clickable Images Controls Other Than Buttons Have Click Event Procedures

30. Starting Out with Visual Basic.NET 2 nd Edition 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

31. Starting Out with Visual Basic.NET 2 nd Edition PicutreBox 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

32. Starting Out with Visual Basic.NET 2 nd Edition 2.7 Using Visual Basic.NET Help In This Section You Learn to Use the Visual Basic.NET Help System

33. Starting Out with Visual Basic.NET 2 nd Edition 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

34. Starting Out with Visual Basic.NET 2 nd Edition 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

35. Starting Out with Visual Basic.NET 2 nd Edition 2.8 Debugging Your Application At Some Point, Most Applications Contain Bugs, or Errors That Prevent the Application From Operating Properly

36. Starting Out with Visual Basic.NET 2 nd Edition 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

37. Starting Out with Visual Basic.NET 2 nd Edition 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