Making Your Own Custom Control

by Sam Huggill

Making your own custom control

Ever wondered how to put all of your 500-line code into your own control? Well now there's a way.

Using the Visual Basic 5 Control Creation Edition or Visual Basic 5 (although the CCE is free), you can create your own controls. This has been very beneficial to companies such as Data-Dynamics and Sheridan. They have made a lot of money with their own controls (see my previous article on custom controls).

Well, in the next two weeks I will show you a simple demonstration of how to make two different types of controls.

The first will make your program stay 'on top'. Make a new ActiveX control and add a .bas module (Project, Add Module). This first piece of code sets some constants and uses an API call on the 'user32' library. Add this code to the module:

Public Const HWND_TOPMOST = -1
Public Const HWND_NOTOPMOST = -2
Public Const SWP_NOMOVE = &H2
Public Const SWP_NOSIZE = &H1
Public Const SWP_NOACTIVATE = &H10
Public Const SWP_SHOWWINDOW = &H40
Public Declare Function SetWindowPos Lib "user32" _
(ByVal hwnd As Long, ByVal hWndInsertAfter As Long, _
ByVal x As Long, y, ByVal cx As Long, ByVal cy As Long, _
ByVal wFlags As Long) As Long

By default, the control name is 'UserControl1'. Change its name to something relevant like 'OnTop'. Change the CanGetFocus property to False and the InvisibleAtRunTime property to True. Give it a nice picture and leave the ToolboxBitmap property to None, unless you feel the desire to give it a meaningless picture!

Open up the code window for the Control, and go to the General Declarations procedure. This code adds a method statement, which makes the program 'normal':

Public Sub MakeNormal(Handle As Long)
SetWindowPos Handle, HWND_NOTOPMOST, 0, 0, 0, 0, _
End Sub

Now add this method statement to put the program on top:

Public Sub MakeTopMost(Handle As Long)
SetWindowPos Handle, HWND_TOPMOST, 0, 0, 0, 0, _
End Sub

Right, time to compile the control. Click File, Make OnTop.ocx. Now save the project (File, Save Project).

Click File, New Project. Select a Standard EXE file. Click Project, Components. Click on the Browse button. Go to the directory where you made the OCX file and double click on it. Click OK. Draw the control on to the form. Open up the code window for the form. Go to the form's Load procedure. Add this code:

Private Sub Form_Load()
OnTop1.MakeTopMost (Me.hwnd)
End Sub

Or, if you want it to become normal, use:

Private Sub Form_Load()
OnTop1.MakeNormal (Me.hwnd)
End Sub

Run the Project (F5).

So, you have made your own control which keeps your program on top, but now you want people to know that it was you that made it. Your claim to fame!

Well, as last time, load Visual Basic and choose "ActiveX Control" from the New Project dialog. Open up the code window for the control and go to the General Declarations procedure. Add this code which declares your name and web site address as a string:

Private mvarauthor As String
Private mvarURL As String

Now add these four pieces of code which store and retrieve the settings:

Public Property Let URL(ByVal vData As String)
mvarURL = vData
End Property

Public Property Get URL() As String
URL = mvarURL
End Property

Public Property Let author(ByVal vData As String)
mvarauthor = vData
End Property

Public Property Get author() As String
author = mvarauthor
End Property

Now add two labels to the control, and change the caption properties on each one to your name and web site address. e.g.

Lblname.caption="Sam Huggill"

Almost finished. Open the code window for the control and go to the Controls Initialise procedure and add this code:

Private Sub UserControl_Initialize()
Me.author = lblName.Caption
Me.URL = lblURL.Caption
End Sub

Now click File, Make Project1.ocx. Select a directory for the file. Now, make a new project and click Project, Components. Click browse, go to the directory where the file is. Double click on the file and click OK. Draw the control onto the form and look at the properties. See, it works!

If you would like to discuss any of the points touched upon in this article then please e-mail me at: shuggill@domain.softnet.co.uk or check my web site at: http://www.soft.net.uk/domain/. If you would like to subscribe to my FREE weekly VB newsletter then send an e-mail with the subject line of 'subscribe'.

Thanks for reading

Sam Huggill

This article was originally published on Wednesday Nov 20th 2002
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