Form With A Hole In It

Over the weekend, I saw this VB program in which one of the forms had a "hole" in it. I mean you could actually see the desktop through this "hole" in the form.

Anyone know how to do that?

Create A Form With A Hole In It

From www.vbcode.com

VB Code:

'1, Declararion
Private Declare Function CreateRoundRectRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long, ByVal X3 As Long, ByVal Y3 As Long) As Long
Private Declare Function CreateRectRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long
Private Declare Function CreateEllipticRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long
Private Declare Function CombineRgn Lib "gdi32" (ByVal hDestRgn As Long, ByVal hSrcRgn1 As Long, ByVal hSrcRgn2 As Long, ByVal nCombineMode As Long) As Long
Private Declare Function SetWindowRgn Lib "user32" (ByVal hWnd As Long, ByVal hRgn As Long, ByVal bRedraw As Long) As Long
 
'2  The Function
 
 
Private Function fMakeATranspArea(AreaType As String, pCordinate() As Long) As Boolean
 
'Name: fMakeATranpArea
'Author: Dalin Nie
'Date:   5/18/98
'Purpose: Create a Transprarent Area in a form so that you can see through
'Input:  Areatype : a String indicate what kind of hole shape it would like to make
'        PCordinate : the cordinate area needed for create the shape:
'         Example: X1,  Y1, X2, Y2 for Rectangle
 
 
'OutPut: A boolean
 
Const RGN_DIFF = 4
 
Dim lOriginalForm As Long
Dim ltheHole As Long
Dim lNewForm As Long
Dim lFwidth As Single
Dim lFHeight As Single
Dim lborder_width As Single
Dim ltitle_height As Single
 
 
 On Error GoTo Trap
    lFwidth = ScaleX(Width, vbTwips, vbPixels)
    lFHeight = ScaleY(Height, vbTwips, vbPixels)
    lOriginalForm = CreateRectRgn(0, 0, lFwidth, lFHeight)
    
    lborder_width = (lFHeight - ScaleWidth) / 2
    ltitle_height = lFHeight - lborder_width - ScaleHeight
 
Select Case AreaType
  
    Case "Elliptic"
 
            ltheHole = CreateEllipticRgn(pCordinate(1), pCordinate(2), pCordinate(3), pCordinate(4))
 
    Case "RectAngle"
   
            ltheHole = CreateRectRgn(pCordinate(1), pCordinate(2), pCordinate(3), pCordinate(4))
 
      
    Case "RoundRect"
             
               ltheHole = CreateRoundRectRgn(pCordinate(1), pCordinate(2), pCordinate(3), pCordinate(4), pCordinate(5), pCordinate(6))
 
    Case "Circle"
               ltheHole = CreateRoundRectRgn(pCordinate(1), pCordinate(2), pCordinate(3), pCordinate(4), pCordinate(3), pCordinate(4))
    
    Case Else
           MsgBox "Unknown Shape!!"
           Exit Function
 
       End Select
 
    lNewForm = CreateRectRgn(0, 0, 0, 0)
    CombineRgn lNewForm, lOriginalForm, _
        ltheHole, RGN_DIFF
    
    SetWindowRgn hWnd, lNewForm, True
    Me.Refresh
    fMakeATranspArea = True
Exit Function
 
Trap:
     MsgBox "error Occurred. Error # " & Err.Number & ", " & Err.Description
 
 
End Function
 
' 3'To Call
Dim lParam(1 To 6) As Long
 
lParam(1) = 100
lParam(2) = 100
lParam(3) = 250
lParam(4) = 250
lParam(5) = 50
lParam(6) = 50
 
'Call fMakeATranspArea("RoundRect", lParam())
'Call fMakeATranspArea("RectAngle", lParam())
Call fMakeATranspArea("Circle", lParam())
'Call fMakeATranspArea("Elliptic", lParam())

P.S. Looks like you've got an interesting interface in the making, judging by your previous post :)

So near, yet so far :)

Nice piece of code SLH...

Thanks guys! :D

Here's another piece of code that does it.

VB Code:

Private Declare Function GetWindowRgn Lib "user32" (ByVal hWnd As Long, ByVal hRgn As Long) As Long
Private Declare Function CreateEllipticRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long
Private Declare Function CreateRectRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long
Private Declare Function SetWindowRgn Lib "user32" (ByVal hWnd As Long, ByVal hRgn As Long, ByVal bRedraw As Boolean) As Long
Private Declare Function CombineRgn Lib "gdi32" (ByVal hDestRgn As Long, ByVal hSrcRgn1 As Long, ByVal hSrcRgn2 As Long, ByVal nCombineMode As Long) As Long
Private Const RGN_XOR = 3
 
Private Sub Form_Load()
    
    Dim hCurRgn As Long
    Dim hHoleRgn As Long
    Dim hNewRgn As Long
    Dim nWidth As Long, nHeight As Long
    Dim nSize As Long
 
    nWidth = Me.Width / Screen.TwipsPerPixelX
    nHeight = Me.Height / Screen.TwipsPerPixelY
 
    hNewRgn = CreateRectRgn(0, 0, nWidth, nHeight)
    hHoleRgn = CreateEllipticRgn(100, 100, 250, 250)
    CombineRgn hNewRgn, hNewRgn, hHoleRgn, RGN_XOR
    SetWindowRgn hWnd, hNewRgn, True
    
End Sub

Nice code Megatron. But you shouldn't put the code to make the hole in Form_Load, try maximize the form and you'll see what I mean...

Put the code you have in Form_Load in Form_Resize instead and it'll work much better

Quote:

---

Originally posted by McCain
Nice code Megatron. But you shouldn't put the code to make the hole in Form_Load, try maximize the form and you'll see what I mean...

Put the code you have in Form_Load in Form_Resize instead and it'll work much better

---

Very good point. I tried Megatron's code yesterday when he posted it (and I like it very much. Much better than the code on the link I posted :D) and it worked great, but, I didn't maximize the form when I was running it.

This does work better in Form_Resize!

Thanks McCain. :)

Oops. Didn't see that.

Although the only problem with putting it in the resize event is that these regions will constantly be created every time the form is resized thereby using up resources.

A couple DestryObjects in there should do the trick though.

But how often does the form resize? If it's only when you actually change the size of the form it shouldn't be that bad, should it?

I think the form's resize event gets called WHILE you are resizing it, so it would get called a lot.

SLH is correct.

And by the way, I made a typo in my previous post. The function name is DeleteObject, not DestroyObject.

How do we make the controls on the form visible even when a hole is punched in the form.

Just make sure they are out of the way of the hole (in the region specified). If you want them to be in the middle of the hole, make a rectangular region where you want it to be and OR it with the existing region.

I put this code in just to see how many times form_resize actualy gets called...

VB Code:

Dim intSize As Integer
 
Private Sub Form_Resize()
    intSize = intSize + 1
    Me.Caption = intSize
End Sub

If you maximize the form it only gets called once but if you resize it using the mouse it can get called 100+ times... So I guess we do need the DeleteObject...

Quote:

---

Originally posted by Sastraxi
Just make sure they are out of the way of the hole (in the region specified). If you want them to be in the middle of the hole, make a rectangular region where you want it to be and OR it with the existing region.

---

That is pretty interesting but how do we actually do it?

AttnSue: If I can ask, why you want a form with a hole in it?

Thanks.