Chapter 8: Writing Graphical User Interfaces Visual Basic.NET Programming: From Problem Analysis to Program Design

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5 Understanding the Code Generated by the Windows Form Designer Use drag-and-drop features of Windows Form Designer to create GUIs Visual programming consists of: –Creating a form –Setting its properties –Adding components –Setting component properties –Adding event handling code

Visual Basic.NET Programming: From Problem Analysis to Program Design6 Understanding the Code Generated by the Windows Form Designer (continued) VB.NET generates code that handles details of form design –Specifies attributes and methods that make form work When creating a form: –Most generated code collapsed under heading “Windows Form Designer generated code” Begins with #Region directive Ends with #End Region directive –View by clicking expand node –Generated code is complex

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8 Exploring the FormDemo Program (continued) Private keyword –Indicates that method is accessible only within own class Me keyword –Refers to current object Parameter list –Identifies variables that receive values when method invoked

Visual Basic.NET Programming: From Problem Analysis to Program Design9 Exploring GUI Design Principles Standards that guide creative process of user interface design Basic principles include: –Creating consistent look and feel –Ensuring ease of use –Minimizing data entry errors –Providing feedback to users –Adhering to standard naming conventions

Visual Basic.NET Programming: From Problem Analysis to Program Design10 Creating a Consistent Look and Feel Look and feel –Style and appearance of form –Includes choice of colors and fonts for various controls Key design goal –Provide consistent look and feel as user moves among various forms

Visual Basic.NET Programming: From Problem Analysis to Program Design11 Ensuring Ease of Use and Minimizing Data-Entry Errors Purpose of each control and layout of form should be intuitive Placement and grouping of controls should be logical Good practice: –Design input forms to minimize required keystrokes

Visual Basic.NET Programming: From Problem Analysis to Program Design12 Providing Feedback to the User Provide feedback to user –When certain actions have been completed –To inform user when data entry errors have occurred Present feedback in consistent manner

Visual Basic.NET Programming: From Problem Analysis to Program Design13 Naming Conventions Adhering to set of naming conventions –Improves program readability –Facilitates program maintenance Assign meaningful variable names –Change Name property for each control Variable name should reflect both –Type of control –Purpose of control

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Visual Basic.NET Programming: From Problem Analysis to Program Design15

Visual Basic.NET Programming: From Problem Analysis to Program Design16 Handling Events Forms are event-driven: the user has to do something (take an action) for an event to happen (e.g. calculate, display) To create event handling procedure: –Double-click control in Forms Designer window –VB.NET places method header in Code window –Add statements that handle event –Code is added to most commonly used event handler for control See Ex. 8-1

Visual Basic.NET Programming: From Problem Analysis to Program Design17 Working with Additional GUI Controls Other commonly used controls: –Text boxes: See Ex. 8-2 –Combo boxes –Check boxes –Radio buttons

Visual Basic.NET Programming: From Problem Analysis to Program Design18 Using Text Boxes and Combo Boxes Text box –Used to display textual information –Enable inputting of text from keyboard –Property Text: identifies the text contained in the text box Combo box –Extends functionality of text box –Provides ability to select item from predetermined list of values Can also type value –Property Text: identifies the text that is displayed by default in the combo box

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Visual Basic.NET Programming: From Problem Analysis to Program Design20 Using Check Boxes and Radio Buttons Check boxes and radio buttons provide ability to select from options States: –Checked/Selected –Unchecked/Not selected Check box –Appears as small white box –Usually includes label that identifies purpose See Ex. 8-4

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Visual Basic.NET Programming: From Problem Analysis to Program Design22 Using Radio Buttons Radio buttons –Appear as small white circles –Have captions that identify purpose Group of radio buttons –Represents set of related options –Options are mutually exclusive

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Visual Basic.NET Programming: From Problem Analysis to Program Design24

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