Chapter Ten

1. Chapter Ten Using Controls

2. Objectives • Learn about Controls • How to create a Form containing Labels • How to set a Label’s 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 • Control’s 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 Label’s 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 Label’s Font with a statement like label1.Font = myFont

10. Setting a Label’s Font • Font dialog box

11. Setting a Label’s 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 family—they 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 arguments—the 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