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