Partial screen capture via xy and height/width parameters

VB gurus please help:

I want to capture an area of the screen providing the routine xy coordinates and the height and width of the screen area. This capture would be at intervals and once captured comparing the image area captured to a database of .bmp files (small images of approximately 500 bytes preloaded to an array) of same area for comparison to determine if changed.

To get a start on this first of all I would like input as to the use of VB6 or .NET for this endeaver. Secondly, any recommendations as to where I could find routines that would closely resemble this capability.

As always I appreicate any input provided.

Fred Hanna

You can use the GetDesktopWindow() and GetWindowDC() APIs to BitBlt a portion of the Desktop :).

VB Code:

Public Declare Function GetDesktopWindow Lib "user32" Alias "GetDesktopWindow" () As Long
Public Declare Function GetWindowDC Lib "user32" Alias "GetWindowDC" (ByVal hwnd As Long) As Long
Public Declare Function BitBlt Lib "gdi32" Alias "BitBlt" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
 
Dim DesktopDC as Long
 
    DesktopDC = GetWindowDC(GetDesktopWindow())
 
    BitBlt picDest.hDC, 0, 0, Width, Height, DesktopDC, X, Y, vbSrcCopy