Miscellany

This is from the VBKB that comes with VB3. You'll need to make whatever adjustments to the API if your using VB432 or VB5.


How to Copy Entire Screen into a Picture Box in VB for Windows
Article ID: Q80670

Summary:

Using the Windows API call BitBlt, you can capture the entire
Microsoft Windows screen and place the image into a Microsoft Visual
Basic for Windows picture box. You first get the handle to the desktop,
then use the desktop window handle to get the handle to the desktop's
device context (hDC), and finally use the Windows API call BitBlt to
copy the screen into the Picture property of a Visual Basic for
Windows picture box control.

More Information:

Example
-------

1. Start Visual Basic for Windows (VB.EXE). Form1 is created by default.

2. Create a picture box (Picture1) on Form1.

3. Set the following properties:

   Control   Property      Value
   -------   --------      -----

   Picture1  AutoRedraw    True
   Picture1  Visible       False

4. Add the following code:

Global.Bas
----------

Type lrect
    left As Integer
    top As Integer

    right As Integer
    bottom As Integer
End Type
Declare Function GetDesktopWindow Lib "user" () As Integer
Declare Function GetDC Lib "user" (ByVal hWnd%) As Integer

' Note: The following Declare should be on one line:
Declare Function BitBlt Lib "GDI" (ByVal hDestDC%,
                                   ByVal X%,
                                   ByVal Y%,
                                   ByVal nWidth%,
                                   ByVal nHeight%,
                                   ByVal hSrcDC%,
                                   ByVal XSrc%,
                                   ByVal YSrc%,
                                   ByVal dwRop&
                                  ) As Integer


' Note: The following Declare should be on one line:
Declare Function ReleaseDC Lib "User"(ByVal hWnd As Integer,
                                      ByVal hDC As Integer
                                     ) As Integer

Declare Sub GetWindowRect Lib "User" (ByVal hWnd%, lpRect As lrect)
Global Const True = -1
Global Const False = 0
Global TwipsPerPixel As Single

Form1
-----

Sub Form_Click ()
  Call GrabScreen
End Sub

Sub GrabScreen ()

    Dim winSize As lrect

    ' Assign information of the source bitmap.
    ' Note that BitBlt requires coordinates in pixels.
    hwndSrc% = GetDesktopWindow()
    hSrcDC% = GetDC(hwndSrc%)
    XSrc% = 0: YSrc% = 0
    Call GetWindowRect(hwndSrc%, winSize)
    nWidth% = winSize.right             ' Units in pixels.

    nHeight% = winSize.bottom           ' Units in pixels.

    ' Assign informate of the destination bitmap.
    hDestDC% = Form1.Picture1.hDC
    x% = 0: Y% = 0

    ' Set global variable TwipsPerPixel and use to set
    ' picture box to same size as screen being grabbed.
    ' If picture box not the same size as picture being
    ' BitBlt'ed to it, it will chop off all that does not
    ' fit in the picture box.
    GetTwipsPerPixel
    Form1.Picture1.Top = 0
    Form1.Picture1.Left = 0
    Form1.Picture1.Width = (nWidth% + 1) * TwipsPerPixel
    Form1.Picture1.Height = (nHeight% + 1) * TwipsPerPixel

    ' Assign the value of the constant SRCOPYY to the Raster operation.

    dwRop& = &HCC0020

    ' Note function call must be on one line:
    Suc% = BitBlt(hDestDC%, x%, Y%, nWidth%, nHeight%,
                  hSrcDC%, XSrc%, YSrc%, dwRop&)

    ' Release the DeskTopWindow's hDC to Windows.
    ' Windows may hang if this is not done.
    Dmy% = ReleaseDC(hwndSrc%, hSrcDC%)

    'Make the picture box visible.
    Form1.Picture1.Visible = True
End Sub

Sub GetTwipsPerPixel ()
    ' Set a global variable with the Twips to Pixel ratio.
    Form1.ScaleMode = 3
    NumPix = Form1.ScaleHeight
    Form1.ScaleMode = 1
    TwipsPerPixel = Form1.ScaleHeight / NumPix
End Sub

5. Run the program and click on the form.


6. With the mouse, change the size of the form to see more of the
   picture box. With a little work, you can use this as a "screen
   saver" program.