How to determine if there is a scroll bar or not at the end of richtextbox (vb.net)

Question

my question is: how to determine if the scrollbar is at the end or not at the end of a richtextbox?

edit: when I say at the end, I mean that it scrolls completely to the bottom, and not anywhere else.

Answer 1

Take a look GetScrollRangeand GetScrollPosAPI ...

Private Const SBS_HORZ = 0
Private Const SBS_VERT = 1

<DllImport("user32.dll")> _
Public Function GetScrollRange(ByVal hWnd As IntPtr, ByVal nBar As Integer, _
                               ByRef lpMinPos As Integer, _
                               ByRef lpMaxPos As Integer) As Boolean
End Function

<DllImport("user32.dll")> _
Public Function GetScrollPos(ByVal hWnd As Integer, _
                             ByVal nBar As Integer) As Integer
End Function

// ...

Dim scrollMin as Integer = 0
Dim scrollMax as Integer = 0

If(GetScrollRange(rtb.Handle, SBS_VERT, scrollMin, scrollMax) Then
   Dim pos as Integer = GetScrollPos(rtb.Handle, SBS_VERT)

   // Detect if they're at the bottom
EndIf

Notes:

To determine if the scroll bar is visible, call GetWindowLongand checkWS_VSCROLL

To determine the maximum value that the slider can reach, call GetScrollInfo; I think the maximum value

scrollMax - largeChange + 1

Answer 2

:

    const int SB_HORZ          = 0x0000;
    const int SB_VERT          = 0x0001;
    const int WM_HSCROLL       = 0x0114;
    const int WM_VSCROLL       = 0x0115;
    const int SB_THUMBPOSITION = 4;

    private enum ScrollInfoMask : uint
    {
        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)
    }

    [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;
    }

    public int HScrollPosition
    {
        get
        {
            return GetScrollPos(Handle, SB_HORZ);
        }
        set
        {
            SetScrollPos((IntPtr)Handle, SB_HORZ, value, true);
            PostMessageA((IntPtr)Handle, WM_HSCROLL, SB_THUMBPOSITION + 0x10000 * value, 0);
        }
    }

    public int VScrollPosition
    {
        get
        {
            return GetScrollPos(Handle, SB_VERT);
        }
        set
        {
            SetScrollPos((IntPtr)Handle, SB_VERT, value, true);
            PostMessageA((IntPtr)Handle, WM_VSCROLL, SB_THUMBPOSITION + 0x10000 * value, 0);
        }
    }

    public int HScrollPositionMax
    {
        get
        {
            SCROLLINFO scrollInfo = new SCROLLINFO();
            scrollInfo.fMask = (uint)ScrollInfoMask.SIF_ALL;
            scrollInfo.cbSize = (uint)Marshal.SizeOf(scrollInfo);
            GetScrollInfo(Handle, SB_HORZ, ref scrollInfo);

            return scrollInfo.nMax - (int)scrollInfo.nPage;
        }
    }

    public int VScrollPositionMax
    {
        get
        {
            SCROLLINFO scrollInfo = new SCROLLINFO();
            scrollInfo.fMask = (uint)ScrollInfoMask.SIF_ALL;
            scrollInfo.cbSize = (uint)Marshal.SizeOf(scrollInfo);
            GetScrollInfo(Handle, SB_VERT, ref scrollInfo);

            return scrollInfo.nMax - (int)scrollInfo.nPage;
        }
    }

"" . nPage ( ) GetScrollRange, HScrollPosition, :

if (_rtb.VScrollPosition == _rtb.VScrollPositionMax)
{
    Debug.WriteLine("Scroll is at the bottom most edge");
}

Answer 3

        if (richTextBox1.Size.Width - richTextBox1.ClientSize.Width > 10) 

, VB.NET . :)

Answer 4

- GetScrollPos. VB.NET.

http://www.codeproject.com/KB/vb/VbNetScrolling.aspx?print=true