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Chapter 2

Chapter 2. Creating a First VB .NET Solution. Objectives. Explore the role of the developer Examine the steps in creating and saving a solution Understand how to design a user interface Set properties at design time Understand the Label, Button, and PictureBox controls

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Chapter 2

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  1. Chapter 2 Creating a First VB .NET Solution

  2. Objectives • Explore the role of the developer • Examine the steps in creating and saving a solution • Understand how to design a user interface • Set properties at design time • Understand the Label, Button, and PictureBox controls • Understand the purpose of the Code Editor • Create an event handler • Understand programming errors and assignment statements

  3. The Role of Author and Developer • As a programmer you use existing tools called components • Components include the controls found in the Toolbox • As the developer, you use components created by others • In this chapter, you will work in the role of the developer • As the author, you create components designed for use by developers

  4. Creating a New Solution • Every program you create is called a solution • Solution file as a suffix of .sln • Each solution is created in its own unique folder • When you create a solution, VB .NET creates the solution folder. It must not already exist • Solution folder contains other folders and all of the files comprising the solution • To copy a solution to another computer, copy the solution folder and all of its contents

  5. Files in The Solution • Chapter.02\Startup02 contains all folders and files comprising solution • Startup02.vbproj is the project file • Startup02.sln is the solution file • Startup02.suo is the solution configuration file • frmMain.vb is the form module • frmmain.resx contains form configuration information • This file is called a resource file • The folders bin and obj contain executable files and debugging information • Note that the structure of a solution differs significantly between VB 6 and VB .NET

  6. Types of Projects • WindowsApplication template creates desktop applications • You will create a Windows Application in this chapter • ClassLibrary template creates components used by other applications • WindowsControlLibrary template creates controls to supplement those provided by VB .NET • ASP.NET Web Applications create dynamic Web pages that execute on a Web server

  7. Creating a New Solution • New Project dialog box allows you to define the: • solution type in the Project Types pane • project template • Select WindowsApplication to create a desktop application • location of the solution • The solution is created in a new folder • Remember that the folder must not already exist • solution name

  8. New Project dialog box Select Windows Application project template Set project name Project created in this folder

  9. Designing the User Interface (1) • Principles of a Good User Interface • Control – The user should control the program not the other way around • User-friendliness – The interface should help the user accomplish tasks and not call attention to itself • Avoid using too many fonts or images • Intuitiveness – The interface should follow a direct style that proceeds logically • Consistency – Use consistent fonts and other elements

  10. Designing the User Interface (2) • Clarity – Visual elements should be readily comprehensible • Feedback – Provide immediate and clear feedback to the user • Advise the user of errors and provide suggestions to correct errors • Graphics – Avoid unnecessary graphics that serve no useful purpose • Use graphics as intuitive metaphors such as a stop sign • Input – Minimize transitions from keyboard to mouse

  11. Visual Elements of Control Instances • Align control instances vertically or horizontally • Distribute control instances evenly about the form • Group control instances together functionally • Control instances should have a similar size • Be aware of screen resolution and size • Minimize use of bright colors • Use bright colors only for emphasis • Provide adequate contrast between foreground and background colors • Similar objects should have similar colors • For example, use the same text and background color for labels

  12. Setting Properties at Design Time • Use the Properties window to set properties for the form and the control instances created on the form • You only use the Properties window to set properties at design time • Form properties • BackColor specifies the form’s background color • FormBorderStyle defines the appearance of the form’s border • Icon defines the icon appearing in the form’s title bar • Width and Height define size of the form or control instance • X and Y define position of the form or control instance

  13. Setting Properties • Enter or select data in value column • Value column operates differently depending on the type of data stored in the property • For some properties you edit text • Set colors using a color palette • Use a dialog box to set properties involving fonts • For properties such as FormBorderStyle, select predefined values from a drop-down list

  14. Properties window Use the list box to select form or control instances (Form1 selected) Size property expandedClick button to expand or collapse property

  15. Setting the Name Property • All forms and control instances have a Name property • Name must adhere to the following rules: • First character must be a letter • Subsequent characters can contain letters and numbers • Name must be less than 255 characters long • Cannot contains special characters other than an underscore • Name cannot contain spaces • Name must be unique

  16. Naming Conventions • Using meaningful names improves code readability • Meaninful names help you the developer. VB .NET does not care about these naming prefixes • This book uses a prefix (usually three characters) for forms, controls and other objects • Form – "frm" • Button – "btn" • Label – "lbl" • OpenFileDialog – "ofd" • PictureBox – "pic"

  17. Renaming a Form (1) • Use Solution Explorer to change the disk file name • Do not change the file extension • Do not rename files using Windows Explorer. Use the Solution Explorer • Use Properties window to set Name property • Apply standard prefix of "frm" followed by a descriptive name • Set startup form as necessary using project’s Property Pages • Note that disk file name and the value of the Name property may be different

  18. Renaming a Form (2) File name of form (frmMain.vb) appears in Solution Explorer

  19. Setting the Startup Object Activate the Property Pages by right clicking project in the Solution Explorer and selecting Property Pages Startup object set to frmMain

  20. Controlling the Form’s Border Style • The FormBorderStyle property controls whether user can resize the form, and the appearance of the form’s border • None – no border • FixedSingle – flat border not resizable • Fixed3D – 3D border not resizable • FixedDialog – for dialog boxes • Sizable – user can resize the form by dragging the border • FixedToolWindow, SizableToolWindow – appears with a shorter title bar

  21. Setting the FormBorderStyle Property Select the desired border style from the drop-down list

  22. Setting the BackColor Property Set BackColor using the color palette

  23. Setting the Font property Set the Font property using the Font dialog box

  24. Setting the TextAlign Property Set the TextAlign property visually

  25. The Control Box • Control box appears at the upper-right corner of the form’s title bar • The control box has three buttons • Left button - Minimize button hides the form • Middle button – Maximizes or restores the window • Right button – Closes the form

  26. Properties Applicable to the Control Box • ControlBox property determines whether the control box appears on the title bar • MaximizeBox property enables or disables the maximize / restore buttons • MinimizeBox enables or disables the minimize button • All of these properties store the value True or False

  27. The Label Control • Used to identify other control instances on a form or display output • User cannot enter text in a label • The standard prefix for the Label control is "lbl"

  28. The Label Control (Properties) • BorderStyle - defines the border surrounding the label • Font - defines the typeface and font size • ForeColor,BackColor – defines the text and background colors respectively • Set these properties using the color palette • Name - defines name of control instance. Must be unique • Remember to use the prefix "lbl" • Text - appears in the visible region of control instance • TextAlign - property defines alignment of text • Visible - determines whether control instance is visible or not. • Possible values are True and False

  29. Creating a Control Instance Toolbox is typically autohidden Select the Label control Create the control instance by drawing it on the form

  30. Moving a Control Instance First, click the control instance to activate it (sizing handles appear) Drag the control instance to its new position

  31. Resizing a Control Instance First, click the control instance to select it Drag the control instance to its new position

  32. Deleting a Control Instance • Click the control instance appearing on the form to select it • Press the Delete key

  33. The Button Control • Create a button that the user clicks • The standard prefix is "btn" • Button control instance fires a Click event when clicked by the user • More on events later in the chapter • The positional properties are the same as the Label control

  34. Button Control (Properties) • Enabled - controls whether button will generate events • Valid values are True and False • FlatStyle - controls visual appearance • Valid values are Flat, Popup, Standard, or System • Image - contains image that appears in button • ImageAlign - defines position of image if an image appears • Text - property contains Button text • Precede a character with an ampersand (&) to define a hot key

  35. Selecting Multiple Control Instances (1) • Useful to set properties for multiple control instances at the same time • Selecting multiple control instances allows you to align them • Two techniques exist to select multiple control instances • Hold down the Shift key, and then click on the desired control instances • Drag a region with the pointer tool • Even if only part of a control instance is in the region, the control instance will be selected • Properties window displays a limited set of properties. No object appears in the Object list box

  36. Selecting Multiple Control Instances (2) Active control instance surrounded with black sizing handles Sizing handles surround three selected control instances

  37. Aligning Multiple Control Instances • Format menu contains menu items to align control instances (selected control instances are aligned) • Align – Align margins with one another • Make Same Size – Make control instances the same size • Horizontal Spacing – Set horizontal spacing between control instances • Vertical Spacing – Set vertical spacing between control instances • Center in Form – Center control instances between the form margins

  38. The PictureBox control • Displays graphical images of varying types • Bitmaps, Gif, and others • Images will stretch and resize based on property settings • Standard prefix is "pic"

  39. The PictureBox Control (Properties) • BorderStyle - controls appearance of surrounding border • Image - contains picture appearing in visible region • SizeMode - controls how image will be resized • Normal – Image size is fixed • StretchImage – Image will resize to fit in the control instance’s visible region • AutoSize – Control instance resizes to fit image • CenterImage – Center image in visible region of control instance

  40. Effect of the SizeMode Property StretchImage Normal AutoSize CenterImage

  41. The OpenFileDialog Control • The purpose is to allow the user to select a file from a standard dialog box • Note that the control just gets file name. It does not open the file • Not visible to the user at run time • Appears in a resizable tray at the bottom of the Win Form Designer • Standard prefix is "ofd" • ShowDialog method displays the dialog box to the user • FileName property contains the name of the file selected by the user

  42. The Code Editor • Formally known as the Code and Text Editor Window • Intelligent text editor used to edit VB .NET and other code • Plus (+) and minus (-) signs appear to expand or collapse code segments • Intellisense technology helps to complete statements by displaying tooltips

  43. Anatomy of the Code Editor Select form or control instance in the Class Name list box Select event in Method Name list box Expand or collapse procedure

  44. Printing the Code for the Solution • You may want to print code for a solution for reference • To print code: • Activate the Code Editor for a module • Click File and then click Print on the VB .NET menu bar

  45. Event Handlers • Event handlers contain one or more VB .NET statements that execute when a user performs an action such as clicking a button User clicks button to exit the solution Windows generates Click event for Exit button Click event (handler) executes for the button Private Sub btnExit_Click(. . .) Handles btnExit.Click Me.Close() End Sub

  46. Creating an Event Handler (1) Select control instance in Class Name list box

  47. Creating an Event Handler (2) Select Event name in Method Name list box

  48. Creating an Event Handler (3) VB .NET creates the event handler

  49. IntelliSense Technology Intellisense technology displays ToolTips and drop-down lists as you type a statement

  50. Type of Programming Errors • Errors classified into 3 types • Syntax errors occur when a statement violates language rules • Run-time errors occur when a program runs • A dialog box appears describing the error • Click Break to highlight the offending statement in the Code Editor • Logic errors occur because of a design or coding problem • A logic error may or may not cause a run-time error

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