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VB Forum / Win API / January 2008Sending scroll messages to external applications
Hello! I am opening documents(*.txt, *.doc, etc.) in external applications(Notepad, Word Viewer, Excel Viewer) and I have to scroll automatically those external applications. I've looked so far in GetScrollInfo, GetScrollRange, ScrollWindow and SetScrollPos on www.pinvoke.net, but I am not sure how to use those methods to control scrolling of external apps. Do you have any ideas or experience how to realize that? Kindly, Thomas All right. I found some interesting information in the MSDN, but I still don't know how to get the handle to a scroll bar. I am using GetScrollInfo() to get information on the scroll bar in a window. It works only with SB_CTL with notepad.exe and the Microsoft Word Viewer(returns 1). SB_VERT returns 0(i am just interested in the vertical scroll bar so far). <code> Public Function Scroll() As Boolean Dim retValue As Boolean Dim si As SCROLLINFO Dim lRet As Integer si = New SCROLLINFO With si .cbSize = Len(si) .fMask = ScrollInfoMask.SIF_ALL End With lRet = GetScrollInfo(New IntPtr(_current_file.pInfo.dwThreadId), ScrollBarDirection.SB_CTL, si) If 0 = lRet Then lRet = System.Runtime.InteropServices.Marshal.GetLastWin32Error() MsgBox("Last Win32-Errorcode: " & lRet.ToString) End If Return retValue End Function </code> "_current_file" is a simple object which stores a file path and the process information about the application which opened it with CreateProcess: <code> Public Structure PROCESS_INFORMATION Public hProcess As IntPtr Public hThread As IntPtr Public dwProcessId As Integer Public dwThreadId As Integer End Structure </code> Is there a way to get to the scroll bar control of the process or window? Regards, Thomas Thomas Wieczorek <wieczo.yo@googlemail.com> schrieb im Beitrag <cee96e82-58ae-4eab-8f02-ffb53f6ee2bb@l32g2000hse.googlegroups.com>... > <code> > ... [quoted text clipped - 3 lines] > Is there a way to get to the scroll bar control of the process or > window? You are using VB.NET, but this newsgroup is dealing with VB <= 6.0 which has not much more in common with VB.NET but the name. So you should ask your question in an appropriate newsgroup - look out for newsgroups with "dotnet" in their names. Just a hint: There have to be four types of scroll bars taken into account: Type 1: Scroll bar control This is a 'real' window of the standard window class "SCROLLBAR". Scroll bar messages and functions of the Windows API for scroll bar controls are supported. Type 2: Standard scroll bar This isn't a window but part of the non-client area of a window with the window style WS_HSCROLL and/or WS_VSCROLL. Scroll bar messages and functions of the Windows API for standard scroll bars are supported, if the window procedure of the window with the standard scroll bar(s) doesn't prevent support. Type 3: Custom scroll bar controls This is a 'real' window either based on the standard window class "SCROLLBAR" or another registered window class (which may have been registered for use by any application or by its 'owner' application only). Support of Windows API scroll bar messages and functions for scroll bar controls depends on the implementation of the window class - they may be supported or not. Usually the documentation of the custom control informs you about this. Type 4: Application specific scroll bar implementation. This is a scroll bar completely handled and drawn by the application, usually without a window of its own. Support of Windows API scroll bar messages and functions depends on the application - but is very unlikely. For type 1 search for a child window of the main window which is of the window class "SCROLLBAR". Then use the retrieved window handle, if any, with Windows API scroll bar messages and functions. For type 2 send/call Windows API scroll bar messages and functions with the window handle of the window in question which has the WS_HSCROLL/WS_VSCROLL window style. For type 3 you have to know the window class name of the custom scroll bar control. Then find the window and call GetScrollInfo() with the retrieved window handle. If this failes, the control doesn't support the Windows API scroll bar functions for scroll bar controls. Then send the found window a SBM_GETSCROLLINFO message. If this failes, the control doesn't support Windows API scroll bar messages for scroll bar controls either. If neither functions nor messages are supported, the only other possible ways are a) using an API for this provided by the control, if any, or b) synthesizing mouse events (see SendInput()). The same is valid for type 4 except that you have to use the handle of the window with the application specific scroll bar implementation.  Signature---------------------------------------------------------------------- THORSTEN ALBERS Universität Freiburg albers@ uni-freiburg.de ---------------------------------------------------------------------- |
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