Chapter Ten

1
Chapter Ten

• Using Controls

2
Objectives

• Learn about Controls
• How to create a Form containing Labels
• How to set a Labels Font
• How to add Color to a Form
• How to add CheckBox and RadioButton objects to a
  Form

3
Objectives

• How to add a PictureBox to a Form
• How to add ListBox, ComboBox, and CheckedListBox
  items to a Form
• How to add functionality to a ListBox with one
  SelectedItem
• How to add functionality to a ListBox with
  multiple SelectedItems
• How to supply a default selection for a ListBox

4
Understanding Controls

• The Control class provides the definition for GUI
  objects such as Forms and Buttons
• The Control class has 23 direct descendants, some
  of which have their own descendants
• The Visual Studio Help documentation can be a
  useful resource when using Controls

5
Understanding Controls

• Controls inheritance hierarchy

6
Understanding Controls

• A MarshalByRefObject object is one you can
  instantiate on a remote computer
• The Component class provides containment and
  cleanup for other objects
• The Control class implements very basic
  functionality required by classes that appear to
  the user
• The Control class handles user input through the
  keyboard and pointing device

7
Creating a Form with Labels

• A Label is one of the simplest GUI Control
  objects you can place on a form
• You typically use a Label control to provide
  descriptive text for another Control
• You can create a Label by calling the class
  constructor

8
Creating A Form with Labels

• FormWithLabels program and Output

9
Setting a Labels Font

• You use the Font class to change the appearance
  of printed text on your Forms
• If the font size contains a decimal point, it
  must be of type float
• You can create a Font using FontStyles
• Once you have defined a Font, you can set a
  Labels Font with a statement like label1.Font
  myFont

10
Setting a Labels Font

• Font dialog box

11
Setting a Labels Font

• Label with new Font, FontStyle, and Size

12
Adding Color to a Form

• The Color class contains a wide variety of
  predefined Colors that you can use with your
  Controls
• Visual Studio also allows you to create custom
  colors
• Examples of using Colors
• label1.BackColor System.Drawing.Color.Blue
• label1.BackColor Color.Blue

13
Using CheckBox and RadioButton Objects

• The ButtonBase class has three direct
  descendants Button, CheckBox, and RadioButton
• When a Form contains CheckBoxes, any number of
  them can be checked or unchecked at the same time
• RadioButtons are similar to CheckBoxes, except
  that when placed on a Form, only one RadioButton
  can be selected at a time
• Both CheckBox and RadioButton objects have a
  Checked property and a CheckedChanged() method

14
Adding a PictureBox to a Form

• A PictureBox is a Control in which you can
  display graphics
• Lincoln Room Form with Image

15
Adding ListBox, CheckListBox, and ComboBox
Controls to a Form

• ListBox,ComboBox, and CheckedListBox objects
  descend from the same familythey all are
  list-type widgets that descend from ListControl
• The ListBox Control enables you to display a list
  of items that the user can select by clicking
• With a ListBox, you can allow the user to make a
  single selection only or multiple selections by
  setting the SelectionMode property

16
Adding Functionality to a ListBox with One
SelectedItem

• The SelectedItem property of a ListBox contains
  the value of the item a user has selected
• The easiest way to add functionality to a ListBox
  is by using the Visual Studio IDE

17
Adding Functionality to a ListBox with One
SelectedItem

• Using the String Collection Editor to type
  ListBox options

18
Adding Functionality to a ListBox with One
SelectedItem

• Selecting a ListBox option to change a Label

19
Adding Functionality to a ListBox with Multiple
SelectedItems

• When you create a ListBox, by default its
  SelectionMode is One
• When a ListBox mode allows for more than one
  selection you use the SelectedItems array that
  contains a list of all currently selected item
  names
• You access each SelectedItems element in the same
  way you access any other array element
• You can determine how many items are selected by
  using the SelectedItems.Count field

20
Adding Functionality to a ListBox with Multiple
SelectedItems

• Application that uses a ListBox that allows
  multiple selections

21
Supplying a Default Selection for a ListBox

• When you execute a program containing a ListBox,
  at first no items are selected highlighting
  appears within a ListBox only after you click an
  option
• You can force an item to be the default by using
  the SetSelected() method
• The SetSelected() method requires two
  argumentsthe position of the item to select and
  a Boolean value

22
Supplying a Default Selection for a ListBox

• Typical execution of Hemingway Homes application

23
Chapter Summary

• The Control class provides the definitions for
  GUI objects
• Typically, you use a Label control to provide
  descriptive text for another Control object
• You use the Font class to change the appearance
  of printed text on Forms
• The Color class contains a wide variety of
  predefined Colors that you can use with your
  Controls
• The Button, CheckBox, and RadioButton classes all
  descend from ButtonBase

24
Chapter Summary

• A PictureBox is a Control in which you can
  display graphics from a bitmap, icon, JPEF, GIF,
  or other image file type
• ListBox, ComboBox, and CheckedListBox objects
  descend from the same family
• The SelectedItem property of a ListBox contains
  the value of the item a user has selected
• When a ListBox mode allows for more than one
  selection, instead of a SelectedItem field, you
  use a SelectedItems array
• You can use the SetSelected() method to force a
  ListBox item to be the default