GetScrollInfo doesn't work

  • Thread starter Thread starter Alex Fu
  • Start date Start date
A

Alex Fu

I create a utility class, and call

GetScrollInfo(txtHelp, (int)ScrollBarDirection.SB_VERT);

txtHelp is a RichTextBox component instance.





Please tell me why GetScrollInfo doesn't work. Thanks.



-------------------------------------

using System;

using System.Runtime.InteropServices;



namespace Alex.Plan

{

[StructLayout(LayoutKind.Sequential)]

public struct SCROLLINFO

{

public int cbSize;

public uint fMask;

public int nMin;

public int nMax;

public uint nPage;

public int nPos;

public int nTrackPos;

}



public enum ScrollBarDirection

{

SB_HORZ = 0,

SB_VERT = 1,

SB_CTL = 2,

SB_BOTH = 3

}



public enum ScrollInfoMask

{

SIF_RANGE = 0x1,

SIF_PAGE = 0x2,

SIF_POS = 0x4,

SIF_DISABLENOSCROLL = 0x8,

SIF_TRACKPOS = 0x16,

SIF_ALL = SIF_RANGE + SIF_PAGE + SIF_POS + SIF_TRACKPOS

}





/// <summary>

/// Summary description for NativeUtil.

/// </summary>

public class NativeUtil

{

[DllImport("user32.dll")]

private static extern bool GetScrollInfo(IntPtr hwnd, int fnBar,
ref SCROLLINFO ScrollInfo);



public static SCROLLINFO
GetScrollInfo(System.Windows.Forms.RichTextBox richtxt, int fnBar)

{

SCROLLINFO info = new SCROLLINFO();

info.cbSize = Marshal.SizeOf(info);

info.fMask = (int) ScrollInfoMask.SIF_ALL;

GetScrollInfo(richtxt.Handle, fnBar, ref info);

return info;

}

}

}





Regards



Alex
 
Alex Fu said:
public enum ScrollInfoMask
{
SIF_RANGE = 0x1,
SIF_PAGE = 0x2,
SIF_POS = 0x4,
SIF_DISABLENOSCROLL = 0x8,
SIF_TRACKPOS = 0x16,
SIF_ALL = SIF_RANGE + SIF_PAGE + SIF_POS + SIF_TRACKPOS
}
Click to expand...


[System.Flags]
public enum ScrollInfoMask
{
SIF_RANGE = 0x1,
SIF_PAGE = 0x2,
SIF_POS = 0x4,
SIF_DISABLENOSCROLL = 0x8,
SIF_TRACKPOS = 0x10,
SIF_ALL = SIF_RANGE | SIF_PAGE | SIF_POS | SIF_TRACKPOS
}


/claes
 
public enum ScrollInfoMask
{

SIF_RANGE = 0x1,

SIF_PAGE = 0x2,

SIF_POS = 0x4,

SIF_DISABLENOSCROLL = 0x8,

SIF_TRACKPOS = 0x16,

SIF_ALL = SIF_RANGE + SIF_PAGE + SIF_POS + SIF_TRACKPOS

}
Click to expand...

You have translated your ScrollInfoMask enum incorrectly to C#. The SIF_TRACKPOS
element should be 0x10 -- not 0x16.


Best Regards,
Dustin Campbell
Developer Express Inc.
 
Thank you, Mr. Bergefall. The method can work well now. I made two mistakes,
one is 0x16 should be 0x10; the other is RichTextBox.ScrollBars had been set
into NONE by legacy code. This method won’t work well unless the scrollbars
became visible.



Best Regards,



Alex Fu
 
Thank you, Mr. Campbell. The method can work well now. I made two mistakes,
one is 0x16 should be 0x10; the other is RichTextBox.ScrollBars had been set
into NONE by legacy code. This method won't work well unless the scrollbars
became visible. I add some code to show scrollbars before I call the method;
and hide them after the calling.



Best Regards,



Alex Fu
 
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