Chapter 13: Advanced GUI and Graphics Visual Basic.NET Programming: From Problem Analysis to Program...

Chapter 13: Advanced GUI and Graphics

Visual Basic .NET Programming:

From Problem Analysis to Program Design

Visual Basic .NET Programming: From Problem Analysis to Program Design 2

Objectives

• Work with additional GUI controls

• Draw lines, rectangles, and ovals

• Develop GUI classes that interact with a PD class

• Create applications with multiple forms

• Simulate a DA class

• Create an integrated system that simulates interaction with a database


Working with Additional GUI Controls

• Other GUI components:

– Menus

– Group boxes

– Tab pages

• Namespace:

– System.Windows.Forms

• Control

– Superclass of other GUI classes



Using Group Boxes and Panels• Containers

– Enable you to visually and logically organize groups of related controls

• Add components – By drawing them inside group box or panel

• Move panel or group box– All controls within it move together

• Common use of group boxes and panels – Group set of radio buttons





Using Tree Nodes and Tree Views

• Tree view

– Displays group of hierarchically related items

– Each item is represented as instance of TreeNode class

– Useful for displaying hierarchical information



Using Tree Nodes and Tree Views (continued)

• Tree node

– Has a value

– Types:

• Parent

• Child

• Sibling




Example 13-2: Using Tree Views and Tree Nodes

• Declaring variables:

– Dim rootNode, profNode As TreeNode

• Adding to tree:

– control.Nodes.Add(myString)

• Finding selected node:

– myNode = trvCSC.SelectedNode


Example 13-2: Using Tree Views and Tree Nodes

(continued)

• Accessing related nodes:

– myNode.Parent

– myNode.PrevNode

– myNode.NextNode

• Accessing node text:

– myNode.NextNode.Text


Using Tab Controls and Tab Pages

• Tab control

– Provides functionality for set of tab pages

– Instance of TabPage class

– Useful when

• Form requires large number of controls

• Controls can be grouped into logical subsets

– User switches between subsets by clicking appropriate tab





Using Main Menus and Menu Items

• MainMenu and MenuItem classes

– Create menus and submenus for a form

• Main menu control

– Serves as container for menu structure

• Menu items

– Represent individual menu choices within structure


Using Main Menus and Menu Items (continued)

• Menu purposes:

– Provide functionality for common tasks, such as

• Opening and closing files

• Editing text

• Accessing help features

– Can use menus instead of buttons to perform many tasks






Drawing Lines, Rectangles, and Ovals

• VB .NET includes a rich set of classes for drawing graphical elements

• System.Drawing namespace

– Contains classes and structures needed for drawing graphical objects

– Automatically available in Windows applications

• No need to import namespace


Drawing Lines, Rectangles, and Ovals (continued)

• Structure

– Can include:

• Constructors

• Methods

• Properties

• Events

– Value type

• Variable contains actual data for structure




Example 13-5: Using Graphics

• Generate paint event for form:

– Invalidate()

• Event handler parameters

– Sender

• Reference to object that raised event

– e

• Object specific to event being handled


Example 13-5: Using Graphics (continued)

'declare variables needed for drawing

Dim instrumentColor As Color

Dim myBrush As SolidBrush

Dim myPen As Pen


Example 13-5: Using Graphics (continued)

'draw a white rectangle to serve as drawing canvas

g.FillRectangle(New SolidBrush(Color.White), 18, 160, 492, 248)

'Define a brush using the selected Color

myBrush = New SolidBrush(instrumentColor)

'Define a pen using the selected Color

myPen = New Pen(instrumentColor)


Developing GUI Classes that Interact With a PD Class

• Create GUIs that interact with problem domain (PD) class

• Customer PD class contains – Three attributes:

• Name

• Address

• PhoneNo

– Parameterized constructor,

– Get and set accessor methods


Adding a Customer

• Visual programming process

– Generates variables necessary to create GUI

– Does not generate all variables needed to respond to events

• Variables must be added to source code through the Code Editor window


Finding a Customer

• Use ArrayList to simulate interaction with database

– Customer instances created from hard-coded data


Creating Applications with Multiple Forms

• Link multiple forms through GUI that allows you to navigate between forms

– Referred to as main menu GUI

– Uses buttons to navigate between forms

• Event handlers hide and show forms:

– frmAddCustomerGUI.ShowDialog()

– Me.Show()


Creating Applications with Multiple Forms (continued)

• Modal dialog box

– Form must be dismissed before next statement in procedure will be executed

– Use ShowDialog method

• Data Access (DA) class

– Enables sharing of data among forms



Simulating a DA Class

• Simulate interaction with database by using ArrayList of customers

• DA classes provide data storage and retrieval services


Simulating a DA Class (continued)

• DA methods

– Initialize

– GetAll

– AddNew

– Find

– Update


Creating an Integrated System that Simulates Interaction

With a Database

• Modify previously developed forms to use DA class


Modifying the Main Menu Form

• Initialize simulated database

– By invoking Initialize method of CustomerDA class

– Invoked by event handler for Load event


Modifying the Add Customer Form

• Event handler for Add Customer button

– Invokes AddNew method of DA class

– To add Customer instance to simulated database


Modifying the Find Customer Form

• Does not include CreateCustomers method

• PopulateListBox method now invokes DA class method GetAll

– To obtain ArrayList

• Event handler for list box

– Invokes DA class method Find

• Event handler for Update button

– Invokes DA class method Update


Programming Example: Interacting with Multiple PD

Classes• PD classes:

– Person– Student– Professor– Phone

• DA classes:– Student– professor



Summary

• Group boxes and panels

– Containers that enable you to visually and logically organize groups of related controls

• Tree view

– Displays group of hierarchically related items as expandable outline

• Tab control

– Provides functionality for a set of tab pages


Summary (continued)

• Main menu control

– Serves as container for menu structure

• Menu items

– Represent individual menu choices within that structure

• Graphics class contains methods for drawing shapes

• Structures are value types


Summary (continued)

• Event handlers provide two parameters:

– Sender

– e

• Graphical user interface (GUI) classes can interact with problem domain (PD) and data access (DA) classes

Date post:	21-Dec-2015
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Chapter 13: Advanced GUI and Graphics Visual Basic.NET Programming: From Problem Analysis to Program...

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