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Chapter 3.1 Controls. Programming In Visual Basic.NET. Controls in the Toolbox. Those controls that we will use in this class. The Name Property. How the programmer refers to a control in code Name must begin with a letter Must be less than 215 characters long

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Chapter 3.1 Controls

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Chapter 3 1 controls

Chapter 3.1Controls

Programming In

Visual Basic.NET


Controls in the toolbox

Controls in the Toolbox

Those controls that we will use in this class.


The name property

The Name Property

  • How the programmer refers to a control in code

  • Name must begin with a letter

  • Must be less than 215 characters long

  • May include numbers and the underscore

  • Use appropriate 3 character naming prefix


Control name prefixes

Control Name Prefixes


Text box txt

Text Box (txt)

  • Used for user input/data entry

  • Text Property

    • What is displayed in text box

    • What user entered in text box

  • TextAlign Property

    • Controls alignment of text in the Text Box

  • Change Event


Textbox control properties

TextBox Control – Properties

  • BorderStyle - defines the border surrounding the text box

  • ForeColor,BackColor - defines the text color and background color respectively

  • Enabled - controls whether the text box can get focus and will respond to events

  • Locked - controls whether user can change the text appearing in the text box

  • MultiLine - controls whether text will appear on multiple lines

  • MaxLength - defines the maximum number of characters that the user can enter into the text box


Textbox control properties1

TextBox Control – Properties

  • Name - defines name used to reference control instance with code

    • Again, use a standard prefix of "txt"

  • ScrollBars - defines whether vertical or horizontal scroll bars appear in text box

  • Text - contains the text appearing in text box

  • TextAlign - justifies text within the visible region of the control instance

  • X, Y, Height, Width properties define the position and size of the control instance


Textbox methods and events

TextBox - Methods and Events

  • Focus method sets input focus to a text box

  • Enter event fires when text box gets focus

  • Leave event fires when text box loses focus

  • TextChanged event fires when the the textual contents change at run time

    • The event fires for each character typed


Button btn

Button (btn)

  • Used to run/activate an Event Procedure

  • Click event

  • Properties

    • Text – Change the text property to display text to user

    • Image – change image to use a graphic button

    • Forecolor – changes the color of the text displayed

    • Backcolor – changes the color of the button


Label lbl

Label (lbl)

  • Used for

    • Output on a form

    • Identification of objects

    • Directions/Information

  • Cannot by modified by user


Label properties

Label Properties

  • Text – used to display text or instructions to the user

  • Font – change font size, color, appearance

  • Image – use images to draw attention

  • Autosize – adjust the label object to text entered into the text property

  • textAlign – aligns the text displayed on the object


Group box grp

Group Box (grp)

  • Used as containers for other controls such as radio buttons and check boxes

  • Improves readability of form

  • Text Property

    • What is displayed on the top edge of the group box

  • Splits the form object into separate planes

    • allows several groups of radio buttons on one form.


Group box grp1

Group box (grp)

  • Group boxes must be added to the form before other objects are added to them.

    • You can not drag checkboxes or radio buttons from the form to the group box

    • The group box must have the focus of the cursor before you draw your other objects inside them

      • Editing handles must be visible


Check box chk

Check Box (chk)

  • Used for user input/data entry

  • Allows the user to select or deselect 1 or more in any group

  • Checked Property

    • Checked = True

    • Unchecked = False

  • CheckChanged Event – default event


Radio button rdo

Radio Button (rdo)

  • Used for user input/data entry

  • Allows the user to select only 1 in any group

  • First create a group and then create each radio button inside the group

  • Checked Property

    • Checked = True

    • Unchecked = False

  • CheckChanged Event – default event


Picture box pic

Picture Box (pic)

  • Displays/contains a picture/graphic

  • Image Property

    • Complete path and filename of graphic

    • .bmp, .gif (including animated), .jpg, .png, .ico, .emf, .wmf

  • SizeMode Property

    • StretchImage causes graphic to be resized to match the size of the control

  • Visible Property


Other properties

Other Properties

  • BorderStyle Property –None, FixedSingle, Fixed3D

  • Forecolor – changes the color of text inside object

  • Backcolor – changes the color of object

  • Textalign – aligns text property

  • Enable

    • true (user can activate the object),

    • false (object us not available to user)

  • Visible

    • True (object appears on form)

    • False (object is hidden at run time)

  • TabIndex – set the order of the focus for controls on the form


Properties and methods

Properties and Methods

  • Properties can be set at design time in the property box

  • Or they be changed during program execution by statements in your code

    • txtHours.Text = "“ ‘ clears the content

  • Methods are action performed on objects

    • txtHours.focus


Selecting multiple controls

Selecting Multiple Controls

  • SHIFT-Click or CTRL-Click to select/deselect multiple controls

  • Use the mouse to drag a selection box around multiple controls

  • To deselect all selected controls click elsewhere on the form


Selecting multiple controls cont

Selecting Multiple Controls (cont.)

Start

here

Drag

to here

Using mouse to drag a selection box around multiple controls

Multiple selected controls,

observe selection handles.


What can be done with multiple selected controls

What Can be Done with Multiple Selected Controls?

  • Use Format Menu or Layout Toolbar to

    • Align them to each other

    • Make same size

    • Modify the spacing between them

  • Move them as a group

  • Set their common properties


Designing the user interface

Designing the User Interface

  • To the user the Interface should be

    • Easy to understand

    • Familiar

    • Comfortable

    • Organized

    • Sans Serif Fonts are best, not boldface or large

    • Color Neutral Overall

    • Keyboard Accessible


Keyboard access keys

Text=&OK

Text=E&xit

Keyboard Access Keys

  • Also referred to as Hot Keys

  • Underlined Letter

  • User presses ALT + underlined letter

  • Use Windows-Standard Keys

  • Defined using Text Property


Default cancel buttons

Default & Cancel Buttons

  • Default Button

    • Identified visually on Form by its darker outline

    • Responds to ENTER key

    • Form's AcceptButton Property

  • Cancel Button

    • Responds to ESC key

    • Form's CancelButton Property


Focus

Focus

  • One control on a Form always has the Focus

  • Not all control types can receive the focus

  • TabStop Property (applicable only for controls that are capable of receiving the focus)

    • Designates whether a control is allowed to receive the focus; True or False


Tab order

Tab Order

  • User should be able to use TAB key to move the focus through a form in an organized manner; top to bottom, left to right

  • TabIndex Property

    • Number in tab sequence

    • 0 for first control to receive the focus when the form loads

  • In form’s graphic view – Use View Menu, Tab Order to set


Setting tabindex property

Setting TabIndex Property

  • View menu, TabOrder

  • Click on each control in sequence to set TabIndex property of controls automatically


Form s screen location

Form's Screen Location

  • StartPosition Property

    • Manual

    • CenterScreen

    • WindowsDefaultLocation

    • WindowsDefaultBounds

    • CenterParent


Tooltips

ToolTips

  • Small label that is displayed when user places pointer on a control and pauses

  • Usually used with Command Buttons

  • Steps for creating ToolTips

    • Add a ToolTip Control to Form

      • Appears in the Component Tray, pane at bottom of Form Designer where nondisplay controls are shown

    • Set ToolTip on ToolTip1 Property of each control to the text of tip


Tooltip control

ToolTip Control

Component Tray


Clearing text boxes labels

txtName.Text = ""

lblMessage.Text = ""

txtCourse.Clear( )

Clearing Text Boxes & Labels

  • Set Text Property equal to the Empty String

    • Empty String is 2 quotation marks with no space between them ("")

  • Use the Clear Method of a Text Box


Resetting the focus

Resetting the Focus

  • Places the Insertion Point in a Text Box

  • Use the Focus Method

txtName.Focus( )


Checked property of check boxes and radio buttons

Checked Property of Check Boxes and Radio Buttons

  • Selects/Deselects Check Box or Radio Button

  • Set Checked Property

    • True = Checked, selected

    • False = Unchecked, deselected

radRed.Checked = True

chkBold.Checked = False


Vb color constants

VB Color Constants

  • ForeColor and BackColor Properties

  • Use VB Color Constants from the Color Class

  • View complete list in Help by using the keyword Color followed by a period

txtName.ForeColor = Color.AliceBlue

lblMessage.BackColor = Color.White


With and end with

With and End With

  • Change several properties at once in Code

  • Will run more efficiently

With txtName

.Visible = True

.Text ="Lynne"

. Focus( )

End With


Concatenation

Concatenation

  • Think of it as "glueing" text strings together

  • Example: txtFName contains First Name txtLName contains Last Name

lblFullName.Text = txtFName.Text & " " & txtLName.Text

lblNote.Text = "Today's weather is " & txtWeather.Text & "."


Continuing lines of code

Continuing Lines of Code

  • For long lines of code it is more readable to continue them to the next line

  • At the end of the line type Line Continuation Character, a Space followed by an Underscore

lblMessage.Text = txtFName.Text & "" & txtLName.Text & _

", welcome to Aiken Technical College. Today is " & _

txtToday.Text


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