Form Properties

Every form and dialog box is derived from the Form class, which itself is derived from the Control class. Therefore, they share the approximately 100 properties of the Control and Form base classes. Table 5-1 listed many of the most commonly used form properties.

While all of the form properties can be used with either dialog boxes or normal forms, either modal or modeless, several properties are often used to create the "dialog box" look and otherwise control the appearance and behavior of the form. They include those shown in Table 6-1, extracted from Table 5-1 in Chapter 5.

The following example will demonstrate the creation of a dialog box. This example will consist of a very simple form with only a single button. Clicking the button will open a modal dialog box. The dialog box is a separate form in the project, although many of its properties are set programmatically by the parent form.

Create a new project in Visual Studio .NET called DialogDemo.

Drag a button onto the form, change the Text property of the button to Create Dialog Box, and resize the button to fit the text. Rename the button to btnCreate.

Add a second form to the project to serve as the dialog box. To do so, either select the menu item Project Add Windows Form... or right-click on the project name in the Solution Explorer and select Add Add Windows Form.... When the Add New Item dialog box comes up, change the default form name to dlg.cs or dlg.vb, depending on your language. Change the (Name) property of the form to DlgTest.

The new form will show up in the Solution Explorer, along with the original Form1.cs or Form1.vb. Your screen should look something like Figure 6-1. (Note that this project was actually named vbDialogDemo to distinguish it from the C# version.)

Figure 6-1. DialogDemo design

Click on the Form1.vb[Design] (or Form1.cs[Design]) tab at the top of the design window, and then double-click on the button created previously. This will open a code skeleton for the Click event handler in the code window. The Click event is the default event for a Button control. Enter the highlighted code shown in Example 6-1 (for C#) or in Example 6-2 (for VB.NET).

Example 6-1. Click event handler to show dialog box in C#

private void btnCreate_Click(object sender, System.EventArgs e) { Form dlg = new DlgTest( ); dlg.Text = "Dialog Test"; dlg.FormBorderStyle = FormBorderStyle.FixedDialog; dlg.BackColor = Color.Azure; dlg.ControlBox = true; dlg.MaximizeBox = false; dlg.MinimizeBox = false; dlg.ShowInTaskbar = false; dlg.Icon = new Icon(typeof(csDialogDemo.Form1),"INFO.ICO"); dlg.Size = new Size(300,300); dlg.StartPosition = FormStartPosition.CenterScreen; dlg.ShowDialog( ); }

Example 6-2. Click event handler to show dialog box in VB.NET

Private Sub btnCreate_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) _ Handles btnCreate.Click dim dlg as New DlgTest dlg.Text = "Dialog Test" dlg.FormBorderStyle = FormBorderStyle.FixedDialog dlg.BackColor = Color.Azure dlg.ControlBox = true dlg.MaximizeBox = false dlg.MinimizeBox = false dlg.ShowInTaskbar = false dim f as New Form1( ) dlg.Icon = new Icon(f.GetType( ),"INFO.ICO") dlg.Size = new Size(300,300) dlg.StartPosition = FormStartPosition.CenterScreen dlg.ShowDialog( ) End Sub

Before the project will run with this code, the icon file referred to when setting the Icon property needs to be properly located. You could hardwire in a location with a line such as the following:

dlg.Icon = new Icon("c:iconsinfo.ico")

but that raises obvious problems for deployment. A slightly better option would be to include the icon file in the same directory as the executable, in which case the following line of code would work:

dlg.Icon = new Icon("info.ico")

Note that in this case, when developing in Visual Studio .NET, the icon file must be included in the proper output directory, typically the bindebug directory located under the project directory when working in C#, or the bin directory when working in VB.NET.

In either case, this would require installing the actual icon file as part of the deployment. Instead, use the code shown in Example 6-1 or Example 6-2, which presumes that the icon file is included as an embedded resource in the assembly.

To embed the icon file, add it to the project by right-clicking on the project in the Solution Explorer, selecting Add Add Existing Item, and navigating to the icon file. This will add a copy of the file to the project directory. Then select the newly added icon file in the Solution Explorer, go to the Properties window, and change the Build action for the file to Embedded Resource, as shown in Figure 6-2. This will cause the icon file to be included automatically in the compiled assembly, eliminating the need for a separate file in the deployment. (All issues concerning deployment of applications are covered in Chapter 22.)

Figure 6-2. Embedded Resource in project

Running the application and clicking on the button will bring up the dialog box shown on top of the parent form in Figure 6-3.

Figure 6-3. DialogDemo dialog box

The first line of code in the Click event handler in Figure 6-1 or Figure 6-3 instantiates a new form of type dlgTest, which is the name you gave the form created previously in Visual Studio .NET. The last line of code in the method shows the form modally, using the ShowDialog method. All the lines in between set various properties to control the appearance and behavior of the dialog box. Each property is described in Table 6-1.