Any 'Windows Service' Experts? Why can't I capture the screen??

25 Apr 2006 1:43 AM

gwhite1

I use this code to capture a screen in a regular VB 2005 windows app.
It works great! I found the code in google. But when I create a windows
service it does not capture the screen. It only captures a blank
graphic. Does anyone know why it will not capture the current screen?
Is something not available when running as a service? Thanks!!!
Sheila

    Function CreateScreenshot() As System.Drawing.Bitmap
        Dim Rect As System.Drawing.Rectangle =
System.Windows.Forms.Screen.PrimaryScreen.Bounds
        Dim gDest As System.Drawing.Graphics
        Dim hdcDest As IntPtr
        Dim hdcSrc As Integer

        CreateScreenshot = New System.Drawing.Bitmap(Rect.Right,
Rect.Bottom)
        gDest = gDest.FromImage(CreateScreenshot)

        hdcSrc = GetDC(0)
        hdcDest = gDest.GetHdc
        BitBlt(hdcDest.ToInt32, 0, 0, Rect.Right, Rect.Bottom, hdcSrc,
0, 0, SRCCOPY)
        gDest.ReleaseHdc(hdcDest)
        ReleaseDC(0, hdcSrc)
    End Function

25 Apr 2006 3:46 AM

Chris

gwhi***@kc.rr.com wrote:
Show quoteHide quote

> I use this code to capture a screen in a regular VB 2005 windows app.
> It works great! I found the code in google. But when I create a windows
> service it does not capture the screen. It only captures a blank
> graphic. Does anyone know why it will not capture the current screen?
> Is something not available when running as a service? Thanks!!!
> Sheila
>
>     Function CreateScreenshot() As System.Drawing.Bitmap
>         Dim Rect As System.Drawing.Rectangle =
> System.Windows.Forms.Screen.PrimaryScreen.Bounds
>         Dim gDest As System.Drawing.Graphics
>         Dim hdcDest As IntPtr
>         Dim hdcSrc As Integer
>
>         CreateScreenshot = New System.Drawing.Bitmap(Rect.Right,
> Rect.Bottom)
>         gDest = gDest.FromImage(CreateScreenshot)
>
>         hdcSrc = GetDC(0)
>         hdcDest = gDest.GetHdc
>         BitBlt(hdcDest.ToInt32, 0, 0, Rect.Right, Rect.Bottom, hdcSrc,
> 0, 0, SRCCOPY)
>         gDest.ReleaseHdc(hdcDest)
>         ReleaseDC(0, hdcSrc)
>     End Function
>

The windows service runs in it's own session. This is why you can't
make an interactive service and you can't screen capture.

Chris

25 Apr 2006 4:03 AM

gene kelley

On 24 Apr 2006 18:43:47 -0700, gwhi***@kc.rr.com wrote:

Show quoteHide quote

>I use this code to capture a screen in a regular VB 2005 windows app.
>It works great! I found the code in google. But when I create a windows
>service it does not capture the screen. It only captures a blank
>graphic. Does anyone know why it will not capture the current screen?
>Is something not available when running as a service? Thanks!!!
>Sheila
>
>    Function CreateScreenshot() As System.Drawing.Bitmap
>        Dim Rect As System.Drawing.Rectangle =
>System.Windows.Forms.Screen.PrimaryScreen.Bounds
>        Dim gDest As System.Drawing.Graphics
>        Dim hdcDest As IntPtr
>        Dim hdcSrc As Integer
>
>        CreateScreenshot = New System.Drawing.Bitmap(Rect.Right,
>Rect.Bottom)
>        gDest = gDest.FromImage(CreateScreenshot)
>
>        hdcSrc = GetDC(0)
>        hdcDest = gDest.GetHdc
>        BitBlt(hdcDest.ToInt32, 0, 0, Rect.Right, Rect.Bottom, hdcSrc,
>0, 0, SRCCOPY)
>        gDest.ReleaseHdc(hdcDest)
>        ReleaseDC(0, hdcSrc)
>    End Function

I'm not sure if this is related, but:
With Windows Media Player ver 9 and earlier, you use to be able to
screen capture a running video via the PrintScreen key and the frame
that was playing at the time would show in the resulting capture. With
ver 10 (and possibly from an additional XP upgrade), you no longer can
capture the frame. All you get is a blank media player. Screen capture
of a running video on any other player that I have, here, works as
expected.

I don't recall what MS calls it, but I believe it has something to do
with their attempt to protect media licensing rights.

Gene

25 Apr 2006 4:52 AM

Cor Ligthert [MVP]

GWhite,

A service cannot reach (direct) the screen. (I never tried it, therefore it
was to often written here).

Cor

<gwhi***@kc.rr.com> schreef in bericht
Show quoteHide quote

news:1145929427.640052.51450@v46g2000cwv.googlegroups.com...
>I use this code to capture a screen in a regular VB 2005 windows app.
> It works great! I found the code in google. But when I create a windows
> service it does not capture the screen. It only captures a blank
> graphic. Does anyone know why it will not capture the current screen?
> Is something not available when running as a service? Thanks!!!
> Sheila
>
>    Function CreateScreenshot() As System.Drawing.Bitmap
>        Dim Rect As System.Drawing.Rectangle =
> System.Windows.Forms.Screen.PrimaryScreen.Bounds
>        Dim gDest As System.Drawing.Graphics
>        Dim hdcDest As IntPtr
>        Dim hdcSrc As Integer
>
>        CreateScreenshot = New System.Drawing.Bitmap(Rect.Right,
> Rect.Bottom)
>        gDest = gDest.FromImage(CreateScreenshot)
>
>        hdcSrc = GetDC(0)
>        hdcDest = gDest.GetHdc
>        BitBlt(hdcDest.ToInt32, 0, 0, Rect.Right, Rect.Bottom, hdcSrc,
> 0, 0, SRCCOPY)
>        gDest.ReleaseHdc(hdcDest)
>        ReleaseDC(0, hdcSrc)
>    End Function
>

25 Apr 2006 10:11 AM

Patrice

Try perhaps to check the "allow service to interact with desktop" checkbox.

A service is generally not tied to the desktop. It runs in its own
context...

--
Patrice

<gwhi***@kc.rr.com> a écrit dans le message de news:
1145929427.640052.51***@v46g2000cwv.googlegroups.com...

Show quoteHide quote

>I use this code to capture a screen in a regular VB 2005 windows app.
> It works great! I found the code in google. But when I create a windows
> service it does not capture the screen. It only captures a blank
> graphic. Does anyone know why it will not capture the current screen?
> Is something not available when running as a service? Thanks!!!
> Sheila
>
>    Function CreateScreenshot() As System.Drawing.Bitmap
>        Dim Rect As System.Drawing.Rectangle =
> System.Windows.Forms.Screen.PrimaryScreen.Bounds
>        Dim gDest As System.Drawing.Graphics
>        Dim hdcDest As IntPtr
>        Dim hdcSrc As Integer
>
>        CreateScreenshot = New System.Drawing.Bitmap(Rect.Right,
> Rect.Bottom)
>        gDest = gDest.FromImage(CreateScreenshot)
>
>        hdcSrc = GetDC(0)
>        hdcDest = gDest.GetHdc
>        BitBlt(hdcDest.ToInt32, 0, 0, Rect.Right, Rect.Bottom, hdcSrc,
> 0, 0, SRCCOPY)
>        gDest.ReleaseHdc(hdcDest)
>        ReleaseDC(0, hdcSrc)
>    End Function
>