capture and stream..

[mikepol]

hi all

i'm wondering if it's possible for me to capture certain amount of my screan at an interval, compress it and send it accross a socket?

kindof like vnc...

is it possible in vb?

thanks

[dglienna]

it would not be easy to do, but, as you may have guessed, anything is possible. these programs tend to only send the data that has changed. this makes the job a lot easier, as usually not too much of the screen changes.
Of course, if you are transferring graphical data, as opposed to text, it is that much harder!

[Joacim Andersson]

Capture a part of the screen is easy, sending it across a socket is also fairly simple. Then we come to the compression part... If you capture a part (or all) of the screen VB will store it as an uncompressed bitmap file. You could use some third party tool to compress it to a JPG or GIF before sending it but you probably need to store it as a file on disk first which also takes time.

Here's a quick example on how to store a part of the screen and show it in a picture box on a form.

Private Declare Function GetDesktopWindow _
 Lib "user32.dll" () As Long
 
Private Declare Function GetDC _
 Lib "user32.dll" ( _
 ByVal hwnd As Long) As Long
 
Private Declare Function ReleaseDC _
 Lib "user32.dll" ( _
 ByVal hwnd As Long, _
 ByVal hdc As Long) As Long
 
Private Declare Function BitBlt _
 Lib "gdi32.dll" ( _
 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
 
Private Sub Form_Load()
    With Picture1
        .ScaleMode = vbPixels 'for easier calculations
        .AutoRedraw = True
    End With
End Sub
 
Private Sub Command1_Click()
    Capture 10, 10
End Sub
 
Private Sub Capture(ByVal x As Long, ByVal y As Long)
    'We capture the screen at position x,y and
    'use the width and height of the picture box
    Dim hDesktopDC As Long, hDesktopWnd As Long
    
    hDesktopWnd = GetDesktopWindow
    hDesktopDC = GetDC(hDesktopWnd)
    With Picture1
        BitBlt .hdc, 0, 0, .ScaleWidth, .ScaleHeight, hDesktopDC, x, y, vbSrcCopy
        .Refresh
    End With
    ReleaseDC hDesktopWnd, hDesktopDC
End Sub

Cheers,

[dglienna]

it's much easier sending text only.

[Joacim Andersson]

it's much easier sending text only.

That's true... and that a fish enjoys water is also true