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Project 2
Working with Intrinsic Controls and ActiveX Controls

Intrinsic Controls

• Intrinsic controls - are the basic set of twenty controls in the Toolbox.
• Controls exist within the Visual Basic .exe file
  • do not have to add these to Toolbox
  • can not be removed from the Toolbox

ActiveX Controls

• ActiveX controls - exist as separate files
• in earlier versions of Visual Basic called VBX’s (Visual Basic Extensions) and later OCX’s .ocx extensions
• include these controls by adding them to Toolbox
• Microsoft includes many ActiveX controls with the Professional and Enterprise editions of VB
• thousands of ActiveX controls are available from software vendors

ActiveX Controls

• Over 2000 ActiveX controls are available today. In Addition version 5 is the first version of Visual Basic that enables you to create your own controls. You can create controls from scratch, customize controls, or combine controls to make new controls.

Building a Project
3 Step Process

1.  Create the Interface
2.  Set Properties
3.  Write Code

Form Size and Position

• Resize form - during design-time by changing the values of its Height and Width properties
• Position form - by changing value of its Top and Left properties
  • StartUpPosition property - can be set at design-time to center the form on the desktop
  • Code statements can be used at run-time to center the form on the desktop

Labels and AutoSize Property

• Note: contents of a label control cannot be directly changed by the user
• AutoSize property of a label to True, the label’s size automatically is adjusted to size of label’s caption
• If Property has 2 values (False/True)
  • Double-clicking the name of property switches between values

Labels and Backstyle Property

• BackStyle properties
  • 1 - Opaque - (default) BackColor property displays within the label’s borders
  • 0 - Transparent - color of control below the label (form) displays within the label’s borders

Copying Controls

• Note: Want to add multiple similar controls to a form
• Copy control to Clipboard
• Paste copies from Clipboard to form

List Box Control

• Note: used to present list of choices
• List box - part or all of the list of choices displays
• Scroll bar automatically added if list too long for the size of the list box
• Drop-Down list - list of choices appears only when you click the down arrow located next to the list box

Combo Box Control

• Combo box controls can have different selection methods and can appear differently, depending on how properties set
  • (Style 0) - Drop-down list
    • Selection - click in list or type item in combo box
  • (Style 1) - List always shows; scroll bar added if list is longer than control’s size
    • Selection - click in list or type item in combo box
  • (Style 2) - Drop-down list
    • Selection - click in list

Shape Control

• Shape control is used to add a rectangle, square, ellipse, or circle to a form
• Note: change the shape property of the Shape control in the Properties Window to get the different shapes
• Default shape of Shape Control is (0 - Rectangle) (1-3 other shapes)

Check Box Control

• Check box control is used in applications to turn options on or off
• Clicking an empty check box places an check mark in the box (option selected)
• Clicking on a selected check box removes the check mark (option not selected)
• Note: When placed inside a frame as many check boxes as desired may be selected (not mutually exclusive)

Frame Control

Used as a container for other controls
Differences from Shape Control

1. Only rectangular shape
2. frame can have caption
3. Only one option button can be selected at a time when inside a frame (mutually exclusive)

Option Button Control

• Option buttons present a set of mutually exclusive choices (radio buttons)
• Note: All option buttons on a form function as one group unless they are inside a frame.
• For an option button to be part of a group, it must be added directly inside frame
• Cannot add an option button to form and drag it inside frame

Option Buttons continued

• Cut and Paste method or Double-click method to add option buttons can not be used since they would have added option buttons to the form instead of inside the frame
• Note: Double-clicking on a Control button from the Toolbox always adds the control to the center of the form

TextBox Controls

• At run-time, the Microsoft Windows operating system automatically implements a standard keyboard interface to allow navigation in Textbox controls. The user can enter, edit, and delete text with the ARROW keys (UP, LEFT, DOWN, and RIGHT; and also use the DELETE, BACKSPACE, HOME, and END keys)
• On some Visual Basic controls, a scroll bar is automatically added when contents extend beyond control’s borders. This is not true of text boxes, must use ScrollBars property

Common Dialog Control

• Common dialog control is used in applications to display one of five common dialog boxes at run-time
• Open, Save As, Print, Color, and Font
• Common dialog control invisible (run-time)
• Dialog box opened during run-time - by applying one of the Show methods to CommonDialog control through code
• ActiveX control - must be added to Toolbox before you can add it to an application

Common Dialog Control

• Note: when you choose OK from a color dialog box after selecting a color during run time, the selected color becomes the value of the common dialog control’s Color property
• Through a code statement set BackColor property of another control equal to value of the common dialog control’s Color property

Color Dialog Box
Actions User’s Perspective

1. Color was selected in the dialog box
2. the OK button was chosen
3. a control’s color then changed to the selected color

Note: movie theater attendant will not be able to change the Movie Box Office application’s color. Programmer can use the Color dialog box to show different color possibilities to ANC management. 
(double-click on form to activate - no directions given to user for this)

Aligning Controls

• Use VB6’s Format menu or Form Editor Toolbar to access form layout commands that adjust the alignment, spacing, and size of any group of controls on a form
• Align command - aligns selected objects with each other using the last selected object in a group

Setting Properties
Naming Controls

Note: As controls are added to form Visual Basic assigns a name to control (Default Command1)

Note: Easier to read and edit code if controls have names that represent purpose of control within application. (Better cmdOK)

Visual Basic Controls Prefixes (Table 2-2 VB 2.27)

Adding Items to Drop-Down List
(2 Ways)

1. Design-Time - add items to ComboBox or ListBox control by adding items to the control’s List property
   • use CTRL-Enter at end of each item in list
2. Run-Time - use AddItem method using code

example: (put in Form_Load procedure)

• cboDropDownListBox.Additem "List Item One"
• cboDropDownListBox.Additem "List Item Two"
• cboDropDownListBox.Additem "List Item Three"

Setting Label Properties

• BorderStyle Property - changes border look
  • 0 - None (default)
  • 1 - Fixed Single
  • Note: double-click on property to change
• FontSize Property - changes size of letters
  • Note: FontSize value after current value in list can be selected by double-clicking

Visible Property

• Determines if control can be seen at run-time.
• Used in movie application to make the 5th radio button invisible so that when application starts the user does not see any number of tickets selected on the radio button frame.
• Code can be used to control property

Default Property
Command Buttons

• Default property of a command button allows you to press ENTER key as an alternative to clicking the button
  • change default property to True by double-clicking
• Note: Only one command button on form can have its Default property set to True.
• If a different button is chosen to have this property, Visual Basic will change 1st button to False.

Writing Code

• General format:

Controlname.property = value

Example:

cmdEnter.Default = True

To Save the Form (Steps)

1. Click the Save Project button on Standard toolbar
2. Type Name of Form in File Name box in the Save File As dialog box
3. Click Floppy drive A in the Save in list box
4. Click the button in the Save File As dialog box
5. Type Name of Project in File Name box in the Save Project As dialog box
6. Click the button in the Save Project As dialog box

Movie Box Office Application

• Seven events in the movie box office application require event procedures or subroutines.
• See MOVIE BOX OFFICE EVENT SUMMARY TABLE 2-5 page VB 2.42

General Declarations Subroutine

• Variables - used in code statements to store temporary values
• data type - determines what kind of data the variable can store (numeric or character etc.)

Rules Variable Names

• Begin with a character
• Less than 255 characters long
• Cannot contain punctuation or blank spaces

Variables Continued

• Easiest way to create a variable is to assign a value to variable’s name in a code statement

Example:

rate = 3.5 or name = "John"

• String - character data enclosed in quotation marks

Code that Creates Variables

Implicit and Explicit Variables

• Implicitly declared variables - variables created simply by using them
• Explicitly declared variables - variables declared in a separate code statement

Dim variablename As datatype

• Data types - Byte, Boolean, Integer, Long, Currency, Single, Double, Date, String, Object, Variant, a user-defined type, or an object type
• Scope of Variable - refers to whether a variable is available for use by different subroutines

Variables Continued

• Local Variables - When variables are created simply by using them, they can be used only within the subroutine in which they were created.

Lose their value between calls unless they are declared static

• Global Variables - Variables declared in a special procedure (General Procedure) where both the variable name and data type must be specified. These variables can be shared by many procedures.

Declaration Statement

• General Format:

Dim variablename As datatype

Example:

Dim num As Integer

Note: Case and color automatically changed

Note: VB inspects code for common errors when ENTER key pressed at end of line.

Editor Options

• Visual Basic has several optional code writing and editing features such as automatically verifying correct syntax after you enter a line of code.
• You can enable or disable these features on the Editor tab sheet in the Options dialog box, accessed on the Visual Basic Tools menu

Creating Procedures
Several Controls (Steps)

1. Select control to assign code from Object list box
2. Select desired event from Procedures list box
3. Enter code statements

Order Of Precedence

If... Then...Else Statement
Single - line

General format:

If condition Then true-task Else false-task

Condition - is made up of two expressions and a relational operator.

Example: If chkMatinee.Value = 1 Then price = 3.5 Else price = 5

 

RELATIONAL OPERATORS
 (Table 2-8 VB 2.46)

Format$ function

• General Format:

Format$ (expression, predefined format name)

Example:

Format$ (grosspay, "currency")

Note: function must be called in an expression can not be used by itself

Control.property = Function (argument list)

Format$ function

lblAmtdue.Caption = Format$ (num * price, "currency")

• Currency is a predefined format name (VB will display in dollars and cents)

Note: $ character appended to Format tells VB to change numeric result of expression to a string before it is assigned to caption of label

• Predefined formats (Table 2-9 VB 2.47)
  (General, Currency, Fixed, Standard, Percent, Yes/No)

Option1_Click Subroutine
(3 options)

1. Num variable assigned to number of tickets
2. Determine ticket price
       Value property of check box is 1 if checked 0 if not
3. Calculate amount due (num*price)
       display it as dollars and cents in Amount Due box

Coding Option1_click

Sub Option1_Click ( )

‘calculate and display amount due

num = 1

If chkMatinee.Value = 1 Then price = 3.5 Else price = 5

lblAmtdue.Caption = Format$(num * price, "currency")

End Sub

cmdEnter_Click Subroutine

• Event adds the number of tickets and movie’s name to the top of a scrollable list in the transaction record (txtRecord) and clears the movie name, matinee check box, number of tickets, and amount due.

String Data Functions

• Concatenation - adding strings together (ampersand (&) character used)

name$ = title$ & " " & firstname$ & " " & lastname$

• Chr$ function
• Chr$(10) - line feed code
• Chr$(13) - carriage return code
• Chr$(13) & Chr$(10) when used together causes a new line to be started

Constants

• Constant - similar to variable, reserves space in memory, but remains same during execution of program.
• Const statement - used in General declarations section to define a constant
• Predefined Constants - Visual Basic contains a large set of predefined constants
• vbNewLine - equivalent to the characters chr$(10) & chr$(13)

Combo List Box Principles

• Index - Visual Basic assigns consecutive numbers to items added to Combo Box or List Box
  • first item given an index of 0
• ListIndex property - item selected by user during run-time given the value of that item’s index
  • can select an item from list using code by changing the control’s ListIndex property
  • ListIndex value of -1 means no item selected

Code cmdEnter_Click

Sub cmdEnter_Click ( )

‘Update transaction list and clear settings

txtRecord.Text = num & " " & cboShow.Text & vbNewLine & txtRecord.Text

cboShow.Listindex = -1 ‘list box empties selects blank list item

chkMatinee.Value = 0 ‘uncheck matinee box

Option5.Value = True ‘select invisible button

lblAmtdue.Caption = "" ‘clear caption

End Sub

CommonDialog Control Code

• Show methods - used to display a common dialog during run-time using code with CommonDialog control
• ShowColor method - used to display Color Dialog Box
• Flags property - used to define the dialog box’s properties and behaviors using CommonDialog Control
• Color property of CommonDialog Control is assigned to the BackColor property on controls using code

Project 2
Working with Controls
END

Program Creating Drop-Down Application Requirements

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