我的问题是:如何检测滚动条是否在richtextbox的末尾?编辑:当我说到末尾时,我指的是完全滚动到底部,而不是其他任何地方。
我的问题是:如何检测滚动条是否在richtextbox的末尾?编辑:当我说到末尾时,我指的是完全滚动到底部,而不是其他任何地方。
请查看GetScrollRange
和GetScrollPos
API...
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
注意:
要确定滚动条是否可见,请调用GetWindowLong
并检查WS_VSCROLL
。
要确定滑块可以达到的最大值,请调用GetScrollInfo
;我认为最大值是
scrollMax - largeChange + 1
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;
}
}
获取“正确”的最大值很繁琐。您需要从GetScrollRange返回的最大值中减去nPage(大改变)值,然后才能正确地将其与HScrollPosition属性进行比较,例如:
if (_rtb.VScrollPosition == _rtb.VScrollPositionMax)
{
Debug.WriteLine("Scroll is at the bottom most edge");
}
if (richTextBox1.Size.Width - richTextBox1.ClientSize.Width > 10)
抱歉,您需要自己将其转换为VB.NET。这应该不难 :)
一种方法是使用GetScrollPos函数。以下是使用VB.NET的有点冗长的示例。
http://www.codeproject.com/KB/vb/VbNetScrolling.aspx?print=true