Chapter 2More Controls

Programming in C#. NET

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Objectives

• Use text boxes, group boxes, check boxes, radio buttons, and picture boxes effectively

• Set the BorderStyle property to make controls appear flat or three-dimensional

• Select multiple controls and move them, align them, and set common properties

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Objectives cont.

• Make your projects easy for the user to understand and operate

• Clear the contents of text boxes and labels• Change text color during program execution• Concatenate (join) strings of text• Make a control visible or invisible at run

time by setting its Visible property

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Introducing More Controls

• Text boxes, group boxes, check boxes, radio buttons, and picture boxes are found in the toolbox

• Each class of controls has own properties• To see control properties

– Place control on form and view properties list or

– Click on control and press F1 for Help

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Text Boxes

• Use a text box when you want the user to type some input

• Set the Text property in code to assign a literal for display

• Set the TextAlign property to change alignment of text in the box– HorizontalAlignment.Left– HorizontalAlignment.Right– HorizontalAlignment.Center

• Example: messageText.TextAlign=HorizontalAlignment.Left;

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Group Boxes

• Used as containers for other controls• Make forms easier to understand• Set Text property to words to appear on top

edge of group box

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Check Boxes• Allow user to select or deselect an option• In a group of check boxes, any number may be

selected• The Checked property is set to true if checked

and false if not checked• CheckedChanged event triggers when the user

clicks in a Check Box• Text property sets text to appear next to the box

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Radio Buttons

• Use when only one button of a group may be selected

• Radio buttons placed directly on a form function as a group

• The Checked property is set to true if checked and false if not checked

• Both CheckedChanged and Click event triggers when the user clicks on a Radio Button

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Picture Boxes

• Used to hold an image• Set Image property to the name of a graphic

file• The picture is saved in the form’s .resx file• Set the SizeMode property to

StretchImage to make picture fill the control

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Setting a Border and Style

• Labels, text boxes, and picture boxes have a BorderStyle property

• BorderStyle options – None– FixedSingle– Fixed3D

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Drawing a Line

• Draw a line using the Label control– Set Text property to blank– Set BorderStyle to None– Change Backcolor to color of line– Control size of line using Width and Height

properties

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Selecting Multiple Controls

• Drag a selection box around the controls• Click on one control to select it; Hold down the

Ctrl or Shift key and click on other controls to select

• Use combination of above methods• Click Select All on the Edit menu to select all

controls on a form• Click anywhere on form or on another control to

deselect the controls

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Controls as a Group

• Move controls as a group by clicking on one of the selected controls and dragging the group to a new location

• Set common properties for group of controls using the Properties window

• Align group of controls using buttons on the Layout toolbar or items on the Format menu

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Designing the User Interface

• Design applications to match other Windows applications

• Follow industry standards for color, size, and placement of controls– Windows applications are mostly gray– Color can indicate what is expected of the user– Group controls to aid the user– Use sans serif font on forms and do not make them bold– Limit large font sizes to a few items

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Defining Keyboard Access Keys

• Use access keys (hot keys) for project response with keyboard

• Type an ampersand (&) in front of the character to be the access character

Example: &OK for OK• Use Windows-standard keys whenever possible• Make sure you don’t give two controls the same

access key

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Setting the Accept and Cancel Buttons

• It is sometimes preferable to use the Enter key or Esc key instead of moving the mouse

• Accept button acts as the Enter key– Set the AcceptButton property of form to

button name• Cancel button acts as the Esc key

– Set the CancelButton property of form to button name

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Focus

• One control on the form always has the focus

• Focus may appear as a light dotted line on some controls such as buttons

• Insertion point appears inside a text box that has focus

• Some controls can receive focus and others cannot

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The Tab Order

• Controls that can receive focus have a TabStop property

• The TabIndex property determines the order the focus moves as the Tab key is pressed

• As controls are created, TabIndex is set in sequence

• When program starts, focus is on the control with lowest TabIndex

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The Tab Order cont.

• Label controls cannot receive focus• Default value of TabStop for buttons and

text boxes is true• Default value of TabStop for radio buttons

is false• The tab key takes you to one radio button in

a group; Use arrow keys to move to another radio button in the group

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Setting the Tab Order

• Set each control’s TabIndex property in Properties window

• Can also use Visual Studio .NET feature to set TabIndexes automatically– Open Design window– Select View / Tab Order– Click on controls in desired tab order– Sequence numbers representing tab order on controls

are updated– Select View / Tab Order to hide sequence numbers

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Setting the Form’s Location on the Screen• By default, the form appears in the upper-left

corner of the screen• Set form’s screen position with StartPosition

property• StartPosition options

– Manual– CenterScreen– WindowsDefaultLocation– WindowsDefaultBounds– CenterParent

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Creating ToolTips

• Add a ToolTip component to a form• ToolTip control is placed in component tray

at bottom of the Form Designer• Component tray hold controls that do not

have a visual representation at run time• Each control on form has new property:

ToolTip on ToolTip1 (assume name of control is ToolTip1)

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Coding for the Controls

• You can change properties as a project executes

• Examples include clearing out contents of a text box or label, resetting the focus, and changing the color of text

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Clearing Text Boxes and Labels

• Set Text property to an empty string• Empty string shown as “”• Use the Clear() method• Set the Text property to string.Empty• Examples: nameTextBox.Text = “”;

messageLabel.Text = “”;dataEntryTextBox.Clear();messageLabel.Text = string.Empty;

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Resetting the Focus

• Use the Focus method to reset the focus to a particular control

• Example: nameTextBox.Focus();

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Set the Checked Property of Radio Buttons and Check Boxes

• Select or deselect a control in code by setting the Checked property to true or false

• Must use lowercase for true or false• Examples:

redRadioButton.Checked = true; //Select buttondisplayCheckBox.Checked = true; //Make box checkeddisplayCheckBox.Checked = false; //Make box unchecked

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Setting Visibility at Run Time

• Use Visible property to set visibility• Example: messageLabel.Visible = false;• Can make visibility depend on selection

user makes in a check box or radio button• Example:

messageLabel.Visible = displayCheckBox.Checked;

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Changing the Color of Text

• Use ForeColor property to change the color of the text

• Use BackColor property to change the color around the text

• The Color class contains color constants• Type keyword Color and a period to see full list of

available colors• Examples: nameTextBox.ForeColor = Color.Red;

messageLabel.ForeColor = Color.White;

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Concatenating Text

• Join two strings of text using process called concatenation

• Use a plus (+) between the two strings• Example:

messageLabel.Text = “Your name is “ + nameTextBox.Text;

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Continuing Long Program Lines

• You can break a statement at any white space• The end of a statement is determined by the

semicolon• To break in the middle of a literal, you must

concatenate the strings to rejoin them• Example:

greetingsLabel.Text = “Greetings “ + nameTextBox.Text + “: You have been selected to win a free prize. “ +

“Just send us $100 for postage and handling”;

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Writing Event Handlers

• Select the method to respond to an event in the Properties window– Click on Events button at top of window– Select the event and drop down list of available

methods

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Your Hands-On Programming Example

For this example you will write a program that uses many of the new controls and topics introduced in this chapter. The program will input the user’s name and a message and display the two items concatenated in a label. The user can change the color of the label’s text by selecting with radio buttons, and hide or display the output by checking a check box.

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Your Hands-On Programming Example cont.

You will include buttons to display the message in the label, clear the text boxes and label, and exit. Include the keyboard access keys; make the Display button the accept button and make the Clear button the cancel button.

Place a logo on the form. Actually, you will place two picture boxes with different sizes for the logo on the form. Each time the user clicks on the logo, it will toggle the large and small versions of the logo.

Add a ToolTip to the logo that says “Click here”.

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Good Programming Habits

• Make the text in a text box right justified or centered using the TextAlign property

• Use the Checked property of a check box to set other properties that must be true or false

• Always test the tab order on your forms; Fix it if necessary using the TabIndex properties

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Good Programming Habits cont.

• Create multiple controls of the same type by Ctrl-clicking on the tool and drawing the needed controls

• Use text boxes when you want the user to enter or change the text

• Use label controls when you do not want the user to change data

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Summary

• Text boxes are used primarily for user input.• Group boxes are used as containers for other

controls and to group like items on a form.• Check boxes and radio buttons allow the user to

make choices.• The current state of check boxes and radio buttons

is stored in the Checked property.• Picture box controls hold a graphic which is

assigned to the Image property.

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Summary cont.

• The BorderStyle property determines whether the control appears flat or three-dimensional.

• Use a Label control to create a line on a form.• You can select multiple controls and treat them as

a group.• Follow Windows standard guidelines for colors,

control size and placement, access keys, default and cancel buttons, and tab order.

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Summary cont.

• Define keyboard access keys by including an ampersand in the Text property.

• Set the AcceptButton property so the user can press Enter, and set the CancelButton property so the user can press Esc.

• The focus moves from control to control as the user presses the Tab key.

• Add a ToolTip control to a form then set the ToolTip on ToolTip1 property for each control.

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Summary cont.

• Clear the Text property by setting it to an empty string.• Use the Focus method to make a control have focus.• You can set the Checked property of a radio button or

checkbox at run time, and the Visible property of all controls.

• Change the color of text in a control with the ForeColor property.

• Use the color constants to change colors at run time.• Concatenation is the joining of two strings with a plus

sign.