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Is there an easy way to determine if the scroll bar of a richtextbox control is at the bottom?
Regards | | pauldevinedotnet Friday, September 18, 2009 5:53 AM | I quickly glanced the properties and methods of the RichTextBox control, but I could not find a .Net way of doing it. Therefore, I put this code together. It should accomplish what you need. A note: Under Windows 7, I found the function GetScrollInfo() in user32.dll even though MSDN online states that the function belongs to comctl32.dll. Just a heads up in case it fails in Vista or XP.
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
class Win32ScrollBars
{
public enum ScrollBarDisposition
{
Horizontal = 0,
Vertical = 1
}
[Flags]
private enum SBInfoFlags : uint
{
Range = 0x1,
Page = 0x2,
Position = 0x4,
TrackPosition = 0x10,
All = Range | Page | Position | TrackPosition
}
[StructLayout(LayoutKind.Sequential)]
public struct SCROLLINFO
{
public uint size;
public uint mask;
public int min;
public int max;
public uint page;
public int pos;
public int trackPos;
}
[DllImport("user32.dll")]
private static extern bool GetScrollInfo(IntPtr hWnd, ScrollBarDisposition bar, IntPtr lpsi);
public static SCROLLINFO GetScrollBarInfo(Control control, ScrollBarDisposition sbDisp)
{
SCROLLINFO info = new SCROLLINFO();
info.size = (uint)Marshal.SizeOf(typeof(SCROLLINFO));
info.mask = (uint)SBInfoFlags.All;
IntPtr infoPtr = Marshal.AllocHGlobal((int)info.size);
Marshal.StructureToPtr(info, infoPtr, false);
GetScrollInfo(control.Handle, sbDisp, infoPtr);
info = (SCROLLINFO)Marshal.PtrToStructure(infoPtr, typeof(SCROLLINFO));
Marshal.FreeHGlobal(infoPtr);
return info;
}
}
}
The above class should provide you with the information of the scrollbar of your choice. I did the following to achieve what you needed.
private void Form1_Load(object sender, EventArgs e)
{
richTextBox1.Text = "Some really long textj so I get a vertical scroll bar.";
richTextBox1.VScroll += new EventHandler(richTextBox1_VScroll);
}
void richTextBox1_VScroll(object sender, EventArgs e)
{
Win32ScrollBars.SCROLLINFO info = Win32ScrollBars.GetScrollBarInfo(richTextBox1, Win32ScrollBars.ScrollBarDisposition.Vertical);
if (info.pos + info.page == info.max)
{
MessageBox.Show("The scrollbar is at the bottom!");
}
}
This seems to work as required.
MCP - Marked As Answer byAland LiMSFT, ModeratorMonday, September 21, 2009 4:13 AM
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| | webJose Monday, September 21, 2009 3:27 AM | If you use WordWrap you should not see it, and you can always set which ones you want to show.
RichTextBoxScrollBars.Both()
RichTextBoxScrollBars.ForcedBoth()
RichTextBoxScrollBars.ForcedHorizontal()
RichTextBoxScrollBars.ForcedVertical()
RichTextBoxScrollBars.Horizontal()
RichTextBoxScrollBars.Vertical()
RichTextBoxScrollBars.None()
VB.NET to C#
http://www.developerfusion.com/tools/convert/vb-to-csharp/ | | Se3ker385 Friday, September 18, 2009 7:15 AM | Thanks, but not quite what i meant. If the scroll bar is visible I need to detect if the user has move the slider all the way to the bottom of the richtextbox and just wondering if there was a quick way of determining this. | | pauldevinedotnet Sunday, September 20, 2009 11:58 PM | I quickly glanced the properties and methods of the RichTextBox control, but I could not find a .Net way of doing it. Therefore, I put this code together. It should accomplish what you need. A note: Under Windows 7, I found the function GetScrollInfo() in user32.dll even though MSDN online states that the function belongs to comctl32.dll. Just a heads up in case it fails in Vista or XP.
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
class Win32ScrollBars
{
public enum ScrollBarDisposition
{
Horizontal = 0,
Vertical = 1
}
[Flags]
private enum SBInfoFlags : uint
{
Range = 0x1,
Page = 0x2,
Position = 0x4,
TrackPosition = 0x10,
All = Range | Page | Position | TrackPosition
}
[StructLayout(LayoutKind.Sequential)]
public struct SCROLLINFO
{
public uint size;
public uint mask;
public int min;
public int max;
public uint page;
public int pos;
public int trackPos;
}
[DllImport("user32.dll")]
private static extern bool GetScrollInfo(IntPtr hWnd, ScrollBarDisposition bar, IntPtr lpsi);
public static SCROLLINFO GetScrollBarInfo(Control control, ScrollBarDisposition sbDisp)
{
SCROLLINFO info = new SCROLLINFO();
info.size = (uint)Marshal.SizeOf(typeof(SCROLLINFO));
info.mask = (uint)SBInfoFlags.All;
IntPtr infoPtr = Marshal.AllocHGlobal((int)info.size);
Marshal.StructureToPtr(info, infoPtr, false);
GetScrollInfo(control.Handle, sbDisp, infoPtr);
info = (SCROLLINFO)Marshal.PtrToStructure(infoPtr, typeof(SCROLLINFO));
Marshal.FreeHGlobal(infoPtr);
return info;
}
}
}
The above class should provide you with the information of the scrollbar of your choice. I did the following to achieve what you needed.
private void Form1_Load(object sender, EventArgs e)
{
richTextBox1.Text = "Some really long textj so I get a vertical scroll bar.";
richTextBox1.VScroll += new EventHandler(richTextBox1_VScroll);
}
void richTextBox1_VScroll(object sender, EventArgs e)
{
Win32ScrollBars.SCROLLINFO info = Win32ScrollBars.GetScrollBarInfo(richTextBox1, Win32ScrollBars.ScrollBarDisposition.Vertical);
if (info.pos + info.page == info.max)
{
MessageBox.Show("The scrollbar is at the bottom!");
}
}
This seems to work as required.
MCP - Marked As Answer byAland LiMSFT, ModeratorMonday, September 21, 2009 4:13 AM
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| | webJose Monday, September 21, 2009 3:27 AM |
|
index > Windows Forms General > C# richTextBox Control Scroll bar Issue