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Oct 2nd, 2000, 01:50 PM
#1
Thread Starter
Addicted Member
I found the coding to display the desktop, but there's an error somewhere? Can anyone figure out what's wrong
URL:http://support.microsoft.com/support/kb/articles/q140/8/85.asp
Coding:Step-by-Step Example
Start Visual Basic for Windows (VB.EXE). Form1 is created by default.
Add a picture box (Picture1) to Form1.
Set the following properties:
Control Property Value
------------------------------
Picture1 AutoRedraw True
Picture1 Visible False
Add the following code to your .BAS module:
Type lrect
left As Integer
top As Integer
right As Integer
bottom As Integer
End Type
Private Declare Function GetDesktopWindow Lib "user" () As Integer
Private Declare Function GetDC Lib "user" (ByVal hWnd%) As Integer
' Enter the following Declare on one, single line:
Private 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
' Enter the following Declare on one, single line:
Private Declare Function ReleaseDC Lib "User"(ByVal hWnd As Integer, ByVal
hDC As Integer) As Integer
Private Declare Sub GetWindowRect Lib "User" (ByVal hWnd%, lpRect As lrect)
Global TwipsPerPixel As Single
Add the following code to the Form1 Click event procedure:
Private Sub Form_Click ()
Call GrabScreen
End Sub
Public 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
Public 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
Run the program. Click Form1.
Using 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.
OK: When I tried the example I got a whole bunch of undefined variables. When I defined the variables I got an Overflow error Run-time error '6'
Does anyone know what the hell is going on?
212 will lead you to the truth
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