Application Development with .NET (31927) .NET Application Development (32998)
Lecture 7: Windows Forms in C#: Part – 1
Outline
• Windows Forms
• Event Handling basics
• Mouse and Keyboard events
• Controls
• Dialog / Message box
• Buttons, Labels, and Textbox
• Checkboxes and RadioButtons • ListBoxes and ComboBoxes
• GroupBoxes and Panels
• Menus
Windows Forms
• Instead of making console project, make windows form application project.
• A form is a graphical element that appears on your computer’s desktop
• Is a container for components and controls
• Components implement IComponent Interface
• A control is a component that has a graphical interface (such as a button) and event handlers.
Event Handling
• Graphical User Interface’s (GUIs) are event driven
• All controls have events associated with them.
• Examples of events would include mouse and keyboard handling. Controls being moved and resized. Controls being created and closed.
• Events are user actions such as key press, clicks, mouse movements, etc., or some occurrence such as system generated notifications.
• Applications need to respond to events when they occur. For example, interrupts. Events are used for inter-process communication.
• Click in the Properties Window of a Control to create the required event handler. The generates handler will be in the form
private void button1_Click(object sender, EventArgs e)
Creating a Windows Form
Select Windows Forms Application
Creating a Windows Form
Designer view:
Visual representation of the window that will open when a window application is opened.
Title bar has minimize, maximize, and close buttons
“Form1” is the default name of the form, can be changed
– Default blank form
– Similar to a canvas where control can be added
– Controls can be dragged and dropped
– The size and position of the form can be adjusted
– The size and position of the controls can be adjusted
Creating a Windows Form
Code view/Window:
– Double click the Form to switch to code window
– Or Right click on the Form and select View Code
Creating a Windows Form
Toolbox View:
Shows the available Controls for GUI developments
Controls : MessageBox
• MessageBox.Show(Over20overloadedoptions)
• Will display message on the screen in a dialog box. User clicks OK to close box.
Useful for displaying debugging messages, etc. Simple example:
MessageBox.Show(message, title);
MessageBox.Show(“Hello World from MessageBox!”, “My Message”);
Controls : Label
Displays read only text on the application. Can be changed programmatically.
: Drag and Drop the label control from toolbox to the Form
Example:
Controls : Button
A control that the user clicks to trigger a specific action. Creates a button_Click event.
Example:
: Drag and Drop the Button control from toolbox to the Form
Controls : TextBox
Used to display text or can be changed by user. Can be made into a password box by setting the UseSystemPasswordChar property to true.
Example:
: Drag and Drop the TextBox control from toolbox to the Form
UseSystemPasswordChar = true
PasswordChar = *
Controls : CheckBoxes
CheckBoxes allow the user to make multiple selections from a number of options. They have a state that is either checked or unchecked. CheckBox comes with a caption, which you can set in the Text property.
Example:
: Drag and Drop the CheckBox control from toolbox to the Form
if
(checkBox1.Checked == true){}
Controls : RadioButtons
Similar to CheckBoxes with one important exception. Within any container only one radio button can be checked.
: Drag and Drop the RadioButton control from toolbox to the Form
Example:
if
(radioButton1.Checked == true){}
Controls : ListBox
The ListBox control enables you to display a list of items to the user that the user can
select by clicking.
Example:
: Drag and Drop the ListBox control from toolbox to the Form
// For Adding items
listBox1.Items.Add(“Hello”);
// For Single item Selection
MessageBox.Show(listBox1.SelectedItem.ToString());
// For multiple item Seletions
( {
MessageBox.Show(obj.ToString());
}
foreach
Object
obj
in
listBox1.SelectedItems)
Controls : ComboBox
A ComboBox displays a text box combined with a ListBox, which enables the user to select items from the list or enter a new value . Similar to ListBox except we have a drop down list of the items
Example:
: Drag and Drop the ComboBox control from toolbox to the Form
// For Adding items
comboBox1.Items.Add(“Hello”);
// Show selected item
MessageBox.Show(comboBox1.Text);
Controls : Groupboxes 1. GroupBoxes can contain multiple controls.
2. Allows the controls to be moved and hidden all at the same time.
3. GroupBoxes can display a caption and do not have scroll bars.
4. GroupBox control displays a caption.
Controls : Menus
1. A Menu on a Windows Form is created with a MainMenu object, which is a collection of MenuItem objects.
2. Menus provide groups of related commands for Windows Applications
private
void
newToolStripMenuItem_Click
object
sender, EventArgs
e)
{
(
MessageBox.Show(“You are selected MenuItem New”); }
private void openToolStripMenuItem_Click(object sender, EventArgs e)
{
MessageBox.Show(“You are selected MenuItem Open”);
}