Dialog Boxes In C#

DialogResult res = MessageBox.Show("Are you sure you want to Delete", "Confirmation", MessageBoxButtons.OKCancel, MessageBoxIcon.Information);  
if (res == DialogResult.OK) {  
    MessageBox.Show("You have clicked Ok Button");  
    //Some task…  
}  
if (res == DialogResult.Cancel) {  
    MessageBox.Show("You have clicked Cancel Button");  
    //Some task…  
}

Dialog box can be configured to constant by setting FormBorderStyle property to FormBorderStyle.FixedDialog, setting MinimizeBox and MaximizeBox property to false. Framework Class Library(FCL) does not provide class as Dialog. The developer creates custom dialog classes by deriving type from System.Windows.Form base class.

Model dialog is displayed, using ShowDialog() method. Modeless dialog boxes are displayed, using Show() method.

Common Dialog Box

The dialog boxes that are used, which are common to all Windows Application. It performs common tasks like saving a file, choosing a font etc. This provides a standard way to the Application interface.

The examples are given below.

• FontDialog
• ColorDialog
• OpenDialog
• SaveDialog

These dialog boxes are implemented by an operating system, so they can be shared across all the Application that runs on that operating system (Windows).

Steps to use common dialog box

• Instantiate the required common dialog box.
• Set the properties of common dialog box, if required.
• Call its ShowDialog() method to invoke the dialog box.

ShowDialog() returns an enumerated type called DialogResult. It defines the identifiers, which indicates which button was clicked. For example, DialogResult.OK and DialogResult.Cancel are some values that indicates OK or Cancel button were clicked respectively.

Open File Dialog Box

The OpenFileDialog allows you to choose a file to be opened in an Application.

For example, the code is given below.

OpenFileDialog ofd = new OpenFileDialog();  
ofd.Title = "Open a Text File";  
ofd.Filter = "Text Files (*.txt) | *.txt | All Files(*.*) | *.*"; //Here you can filter which all files you wanted allow to open  
DialogResult dr = ofd.ShowDialog();  
if (dr == DialogResult.OK) {  
    StreamReader sr = new StreamReader(ofd.FileName);  
    txtEx.Text = sr.ReadToEnd();  
    sr.Close();  
}

Save File Dialog Box

The SaveFileDialog box is used to allow the user to select the destination and name of the file to be saved.

For example, the code is given below.

SaveFileDialog sfdlg = new SaveFileDialog();  
sfdlg.Filter = "Text Files (*.txt) | *.txt"; //Here you can filter which all files you wanted allow to open  
if (sfdlg.ShowDialog() == DialogResult.OK) {  
    // Code to write the stream goes here.  
} 

The content can be saved to the file, using appropriate class like StreamWriter class in the case of Text Editor Application.

Font and Color Dialog Boxes

FontDialogBox is used to allow the user to select font settings. The ColorDialogBox is used to allow the user to select a color.

For example, the code is given below.

//Font Dialog  
FontDialog fdlg = new FontDialog();  
fdlg.ShowDialog();  
txtEx.Font = fdlg.Font;  
//Color Dialog  
ColorDialog cdlg = new ColorDialog();  
cdlg.ShowDialog();  
txtEx.ForeColor = cdlg.color;   

Output of Color Dialog is given below.

In either case, the properties and methods are available. They can be used to get the selected values or set the values for the dialog box.

Custom Dialog Box

Even though common dialog boxes are useful, they do not support the requirements of domain-specific dialog boxes. Developer need to create their own dialog boxes.

Following steps represent the process of creating Custom Dialog Box

1. Add a form to your project by right clicking the project in Solution Explorer, point to Add and then click Windows Form.
2. In the properties Window, change the FormBorderStyle property to FixedDialog.
3. Customize the appearance of the form, as required.
4. Add controls into this form.

Note

Use ShowDialog() method to open the form as modal dialog box. This method can be used for the custom dialog boxes too. Show() method is used to open the model's dialog box.