Project | in Visual Basic .NET

Printer QR Code ISO/IEC18004 in Visual Basic .NET Project |

information that may be useful in the event. In this case, the sender argument will be a reference to the ActClose button, since that s the object that will generate the Click event. A button s Click event doesn t have any more useful information available, so e is the default object type, System.EventArgs, which is pretty much just a placeholder, and the object from which all of the more interesting e argument types derive. The name of this event handler is ActClose_Click, but if you want to change it to FredAndWilma, that s fine; it won t mess up anything. But you must keep the Handles ActClose.Click clause intact. This is the part that links the event handler to the actual event. The code to close the form is extremely simple. Enter it now, either by using the first code snippet for this chapter or by typing it directly.

' ----- Close the form. Me.Close( )

This statement says, I m the AboutProgram form/object, and I command myself to close. If you run the program right now (press the F5 key), you close the form by clicking on the Close button. Since the AboutProgram form was the only form in the application, closing it automatically ended the entire application, no questions asked. OK, back up to the second item, the web-style links. You could go back to the form surface and double-click on each link label to create an event handler for each label s default event (in this case, the LinkClicked event). But you can also add the event handler subroutines right in the editor, either by typing the code yourself (which is no fun) or by using the two drop-down lists just above the editor window (see Figure 5-8).

The Class Name list appears on the left side. Selecting an entry from this list updates the righthand list, the Method Name list. To add an event handler template for the CompanyWeb s LinkClicked event, first select CompanyWeb from the Class Name list,

|

and then select LinkClicked from the Method Name list. The following code block appears in the code window:

Private Sub CompanyWeb_LinkClicked(ByVal sender As Object, _ ByVal e As System.Windows.Forms. _ LinkLabelLinkClickedEventArgs) _ Handles CompanyWeb.LinkClicked End Sub

This template s argument list is a little more interesting, since its e argument is an object of type System.Windows.Forms.LinkLabelLinkClickedEventArgs. The LinkLabel control allows you to have multiple web-style links in a single control, interspersed among regular text. The e argument has a Link property that tells you which of the links in the control was clicked by the user. Since our labels have only a single link, we won t bother to check it. We ll just show the web page immediately anytime the link is clicked.

' ----- Show the company web page. Process.Start("http://www.timaki.com")

The Process object is part of the System.Diagnostics namespace, and Start is one of its shared members that lets you start up external applications and resources. You pass it any valid URL and it will run using the user s default browser or application for that URL. Let s try it again with the CompanyEmail s LinkClicked event. Add in the template any way you choose and then type or insert the code that starts a new message to an email address.

' ----- Send email to the company. Process.Start("mailto:tim@timaki.com")

The last event to design is one of the first events called in the lifetime of the form: the Load event. It s called just before the form appears on the screen. Double-clicking on the surface of the form creates an event handler template for the Load event. If you prefer to use the Class Name and Method Name drop-down lists instead, select (AboutProgram Events) from the Class Name list before using the Method Name list.

Private Sub AboutProgram_Load(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles Me.Load End Sub