Chapter 5Chapter 5Menus, Common Dialog Menus, Common Dialog Boxes, Sub Procedures Boxes, Sub Procedures

andandFunction ProceduresFunction Procedures

Programming InProgramming In

Visual Basic .NETVisual Basic .NET

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<ALT><F><ALT><F>MenuMenu

Menu ItemsMenu Items

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MenusMenus

• Menu BarMenu Bar

– Contains menus which drop down to display list of Contains menus which drop down to display list of menu itemsmenu items

• Each item has a name and text propertyEach item has a name and text property

• Each item has a click eventEach item has a click event

• Add MainMenu control to formAdd MainMenu control to form

– Appears in the Component Tray, below form, where Appears in the Component Tray, below form, where nondisplay controls are shownnondisplay controls are shown

– Words "Words "Type HereType Here" appear at the top of the form" appear at the top of the form

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Menus (continued)Menus (continued)

Type first Menu hereType first Menu here

MainMenu Control MainMenu Control appears in appears in Component TrayComponent Tray

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Defining MenusDefining Menus

• To create the menus simply type where the words "To create the menus simply type where the words "Type Type HereHere" appear at the top of the form" appear at the top of the form

• Include & symbol as you type to indicate keyboard access Include & symbol as you type to indicate keyboard access keyskeys

• You are actually entering the Text property for a You are actually entering the Text property for a MenuItem objectMenuItem object

• Change MenuItem object names in the Properties window Change MenuItem object names in the Properties window and follow consistent naming conventionsand follow consistent naming conventions

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Submenus Submenus

• Pop up to the right of a menu itemPop up to the right of a menu item

• Filled triangle to the right of the menu item indicates to the Filled triangle to the right of the menu item indicates to the user the existence of a submenuuser the existence of a submenu

• Create submenus by moving to the right of a menu item Create submenus by moving to the right of a menu item and typing the next item's textand typing the next item's text

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Submenus Submenus (continued)(continued)

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Separator BarsSeparator Bars

• Used for grouping menu items according to their purposeUsed for grouping menu items according to their purpose

• Visually represented as a bar across the menuVisually represented as a bar across the menu

• Create using one of two methodsCreate using one of two methods

– Typing a single hyphen for the textTyping a single hyphen for the text

– Right-click on Menu Designer where you want a Right-click on Menu Designer where you want a separator bar and choose Insert Separatorseparator bar and choose Insert Separator

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Coding for Menu ItemsCoding for Menu Items

• Double-click any menu item to open the item’s click event Double-click any menu item to open the item’s click event procedureprocedure

• Write code for the click event procedureWrite code for the click event procedure

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Modifying Menu ItemsModifying Menu Items

• Right-click the Menu Bar to:Right-click the Menu Bar to:

– DeleteDelete

– Insert NewInsert New

– Insert SeparatorInsert Separator

– Edit NamesEdit Names

• Displays menu item Name property rather than Text Displays menu item Name property rather than Text property on formproperty on form

• Drag and Drop menu items to new locationsDrag and Drop menu items to new locations

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Menu PropertiesMenu Properties

• Enabled property, True/FalseEnabled property, True/False

• Checked property, True/FalseChecked property, True/False

– Used to indicate current state of menu item that can be Used to indicate current state of menu item that can be turned on and offturned on and off

• Create keyboard shortcutsCreate keyboard shortcuts

– In Properties window for menu item, select the Shortcut In Properties window for menu item, select the Shortcut propertyproperty

– Make choice from drop-down listMake choice from drop-down list

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Standards for Windows MenusStandards for Windows Menus

• Follow Windows standards for applicationsFollow Windows standards for applications

• Include keyboard access keysInclude keyboard access keys

• Use standards for shortcut keys, if usedUse standards for shortcut keys, if used

• Place File menu at left end of menu bar and end File menu Place File menu at left end of menu bar and end File menu with Exitwith Exit

• Help, if included, is placed at right end of menu barHelp, if included, is placed at right end of menu bar

FFile ile EEdit dit VView Formaiew Formatt HHelpelp

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Common Dialog BoxesCommon Dialog Boxes

• Predefined standard dialog boxes for:Predefined standard dialog boxes for:

– File Opening and SavingFile Opening and Saving

– Font and Color selectionFont and Color selection

– Printing and PreviewingPrinting and Previewing

• Add appropriate Common Dialog control to formAdd appropriate Common Dialog control to form

– Appears in the Component TrayAppears in the Component Tray

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Common Dialog ControlsCommon Dialog Controls

• OpenFileDialogOpenFileDialog

• SaveFileDialogSaveFileDialog

• FontDialogFontDialog

• ColorDialogColorDialog

• PrintDialogPrintDialog

• PrintPreviewDialogPrintPreviewDialog

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Component trayComponent tray

Common dialog controlsCommon dialog controls

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Displaying a Windows Common Dialog Displaying a Windows Common Dialog BoxBox

• Use ShowDialog method to display the common dialog Use ShowDialog method to display the common dialog box at run timebox at run time

• ShowDialog only displays the dialog, it does not do ShowDialog only displays the dialog, it does not do anything elseanything else

ColorDialog1.ShowDialog( )ColorDialog1.ShowDialog( )FontDialog1.ShowDialog( )FontDialog1.ShowDialog( )

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CodeCode

With OpenFileDialog1With OpenFileDialog1 .ShowDialog().ShowDialog()End WithEnd With

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Using the Information from the Dialog Using the Information from the Dialog BoxBox

• Code must be written to retrieve and use the choice made Code must be written to retrieve and use the choice made by the user in the common dialog boxby the user in the common dialog box

• ExampleExample

– Color Dialog displayedColor Dialog displayed

– User selects color and clicks OKUser selects color and clicks OK

– Code must be written to apply the selected color to the Code must be written to apply the selected color to the object(s)object(s)

titleLabel.BackColor = ColorDialog1.Color

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Color and Font DialogsColor and Font Dialogs

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Setting Initial ValuesSetting Initial Values

• Before executing the ShowDialog method, assign the Before executing the ShowDialog method, assign the existing values of the object's properties that will be existing values of the object's properties that will be alteredaltered

• When the dialog box appears, the current values will be When the dialog box appears, the current values will be selectedselected

• If the user presses Cancel, property settings for the objects If the user presses Cancel, property settings for the objects will remain unchangedwill remain unchanged

FontDialog1.Font = subTotalLabel.Font FontDialog1.Font = subTotalLabel.Font or or ColorDialog1.Color = Me.BackColorColorDialog1.Color = Me.BackColor

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Creating Context MenusCreating Context Menus

• Shortcut menus that pop up when you right-clickShortcut menus that pop up when you right-click• Are specific to the component to which user is pointing, Are specific to the component to which user is pointing,

reflecting options available for that component or situationreflecting options available for that component or situation• A context menu does not have a top level menuA context menu does not have a top level menu• Application can have multiple context menusApplication can have multiple context menus

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Creating Context Menus (continued)Creating Context Menus (continued)

• Add ContextMenu component to the formAdd ContextMenu component to the form

– Appears in the Component TrayAppears in the Component Tray

• Click on the words "Click on the words "Context MenuContext Menu", at the top of the form, ", at the top of the form, the words "the words "Type HereType Here" appear" appear

• Click on the words "Click on the words "Type HereType Here" and proceed as you did for " and proceed as you did for the main menuthe main menu

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Connecting the Context Menu to a Form Connecting the Context Menu to a Form or Objector Object

• Set the form or object’s ContextMenu property to the Set the form or object’s ContextMenu property to the name of the ContextMenuname of the ContextMenu

• If there is more than one context menu defined, If there is more than one context menu defined, choose from the listchoose from the list

• Add to the Handles clause of a MainMenu item to use Add to the Handles clause of a MainMenu item to use the same procedure for a related ContextMenu itemthe same procedure for a related ContextMenu item

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Writing General ProceduresWriting General Procedures

• A general procedure is reusable code which can be called A general procedure is reusable code which can be called from multiple proceduresfrom multiple procedures

• Useful for breaking down large sections of code into Useful for breaking down large sections of code into smaller unitssmaller units

• Two typesTwo types– Sub Procedure performs actionsSub Procedure performs actions– Function performs actions AND returns a value (the Function performs actions AND returns a value (the

return valuereturn value))

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Creating a New Sub ProcedureCreating a New Sub Procedure

• In the Editor window enclose the lines of code with a set of In the Editor window enclose the lines of code with a set of Private Sub and End Sub statementsPrivate Sub and End Sub statements

• To use the Sub Procedure, call it from another procedureTo use the Sub Procedure, call it from another procedure

• Code in a Sub Procedure cannot be executed unless called Code in a Sub Procedure cannot be executed unless called from another procedurefrom another procedure

Private Sub ProcedureName( )' Statements in the procedure.

End Sub

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Passing Arguments to Procedures Passing Arguments to Procedures (page 205)(page 205)

• Declare variable as local and pass to any called proceduresDeclare variable as local and pass to any called procedures

• If a sub procedure names an argument, any call to the procedure If a sub procedure names an argument, any call to the procedure must supply the argumentmust supply the argument

• Name of local variable does not need to match name in sub Name of local variable does not need to match name in sub procedure argument listprocedure argument list

• Number of arguments, sequence and data type must matchNumber of arguments, sequence and data type must match

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Passing Arguments ByVal or ByRefPassing Arguments ByVal or ByRef

• ByVal (default)ByVal (default)

– Sends a copy, original cannot be alteredSends a copy, original cannot be altered

• ByRefByRef

– Sends a reference to the memory location where the Sends a reference to the memory location where the original is stored and therefore the original can be original is stored and therefore the original can be alteredaltered

• Examples page 206Examples page 206

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Sub Procedure ExampleSub Procedure Example

Private Sub SelectColor(incomingColor As Color)With ColorDialog1

.Color = incomingColor

.ShowDialog( )End With

End Sub

Private Sub changeTitleButtonColor_Click( )Dim originalColor As Color

originalColor = titleLabel.ForeColorSelectColor(originalColor)titleLabel.ForeColor = ColorDialog1.Color

End Sub

Sub Procedure

CallingProcedure

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Writing Function ProceduresWriting Function Procedures

• In the Editor window enclose the linesIn the Editor window enclose the linesof code with Private Function( ) and End Function of code with Private Function( ) and End Function statementsstatements

• To use the Function, Call it by using it in an expressionTo use the Function, Call it by using it in an expression

• Pass arguments ByVal or ByRefPass arguments ByVal or ByRef

Private Function FunctionName( ) As Datatype' Statements to execute.

End Function

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Returning the Result of a FunctionReturning the Result of a Function

• To return a value to the calling procedure set up a return To return a value to the calling procedure set up a return valuevalue

• The return value will be placed by VB in a variable with The return value will be placed by VB in a variable with the SAME name as the Function's namethe SAME name as the Function's name

OROR

• Use the Return statement to return the valueUse the Return statement to return the value

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Function ExampleFunction Example

Private Sub calculateButton_Click( )Dim salesDecimal As Decimal

salesDecimal = Decimal.Parse(salesTextBox.Text)

commissionLabel.Text = Commission(salesDecimal.ToString("C"))End Sub

CallingProcedure

Private Function Commission(ByVal salesAmountDecimal As Decimal) _ As Decimal

If salesAmountDecimal < 100D ThenCommission = 0D

ElseCommission = 0.15 * salesAmountDecimal

End IfEnd Function

Function

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Functions with Multiple ArgumentsFunctions with Multiple Arguments

• Functions can receive one or more arguments (values)Functions can receive one or more arguments (values)

• Sequence and data type of arguments in Call must exactly match Sequence and data type of arguments in Call must exactly match arguments in function headerarguments in function header

Private Function Payment(ByVal rateDecimal As Decimal, _ ByVal timeDecimal As Decimal, ByVal amountDecimal _ As Decimal) As Decimal

paymentLabel.Text = Payment(Decimal.Parse(rateTextBox.Text), _ Decimal.Parse(yearsTextBox.Text), _ Decimal.Parse(principalTextBox.Text)).ToString( )End Function

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Breaking Calculations into Smaller Breaking Calculations into Smaller UnitsUnits

• Projects with many calculations are easier to understand Projects with many calculations are easier to understand and write if calculations are broken into small unitsand write if calculations are broken into small units

• Each unit should perform one program function or logic Each unit should perform one program function or logic blockblock

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