C# Signature:
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool GetScrollInfo(IntPtr hwnd, int fnBar, ref SCROLLINFO lpsi);
VB Signature:
Declare Function GetScrollInfo Lib "user32" (ByVal hWnd As IntPtr, ByVal fnBar As ScrollBarDirection, ByRef lpsi As SCROLLINFO) As Integer
C# User-Defined Types:
[StructLayout(LayoutKind.Sequential)]
struct SCROLLINFO
{
public uint cbSize;
public uint fMask;
public int nMin;
public int nMax;
public uint nPage;
public int nPos;
public int nTrackPos;
}
private enum ScrollBarDirection
{
SB_HORZ = 0,
SB_VERT = 1,
SB_CTL = 2,
SB_BOTH = 3
}
private 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
}
VB User-Defined Types:
<StructLayout(LayoutKind.Sequential)>Private Structure SCROLLINFO
Public cbSize As Integer
Public fMask As Integer
Public nMin As Integer
Public nMax As Integer
Public nPage As Integer
Public nPos As Integer
Public nTrackPos As Integer
End Structure
Private Enum ScrollBarDirection
SB_HORZ = 0
SB_VERT = 1
SB_CTL = 2
SB_BOTH = 3
End Enum
Private Enum ScrollInfoMask
SIF_RANGE = &H1
SIF_PAGE = &H2
SIF_POS = &H4
SIF_DISABLENOSCROLL = &H8
SIF_TRACKPOS = &H10
SIF_ALL = (SIF_RANGE Or SIF_PAGE Or SIF_POS Or SIF_TRACKPOS)
End Enum
Notes:
None.
Tips & Tricks:
Please add some!
C# Sample Code:
// Returns the width of a UserControl containing a RichTextBox
// such that no horizontal scrollbar will be needed
public int PreferredWidth
{
get
{
int MINWIDTH = 200;
int BORDERWIDTH = SystemInformation.Border3DSize.Width;
int SCROLLBARWIDTH = SystemInformation.VerticalScrollBarWidth;
SCROLLINFO si = new SCROLLINFO();
si.cbSize = Marshal.SizeOf( si );
si.fMask = (int) ScrollInfoMask.SIF_RANGE;
GetScrollInfo( RichTextBox1.Handle, (int) ScrollBarDirection.SB_HORZ, ref si );
int iWidth = si.nMax - si.nMin + 2 * BORDERWIDTH + SCROLLBARWIDTH + 2;
return Math.Max( MINWIDTH, iWidth );
}
}
VB Sample Code:
Private Function GetScrollBarPageSize(ByVal hWnd As IntPtr, ByVal fnBar As Integer) As Integer
Dim si As New SCROLLINFO
With si
.cbSize = Len(si)
.fMask = SIF_PAGE
End With
Dim lRet As Integer = GetScrollInfo(hWnd, fnBar, si)
If lRet <> 0 Then
Return si.nPage
Else
Return -1
End If
End Function
Alternative Managed API:
Do you know one? Please contribute it!
