VSTO Excel Worksheet Scrolling Event

Question

Hello all,I am trying to get an event from Excel when a user is finished scrolling using the scrollbars, the mousewheel etc. Now I could not find any Excel events, so i tried using API's. Basically a window procedure that intercepts scroll messages like msg = WM_HSCROLL OrElse msg = WM_VSCROLL OrElse msg = WM_MOUSEWHEEL etc.This&nbsp;works&nbsp;to&nbsp;get&nbsp;an&nbsp;event&nbsp;when&nbsp;the&nbsp;user&nbsp;starts&nbsp;scrolling&nbsp;(so&nbsp;not&nbsp;when&nbsp;the&nbsp;user&nbsp;finishes).&nbsp;So&nbsp;I&nbsp;need&nbsp;to&nbsp;add&nbsp;a&nbsp;timer&nbsp;and&nbsp;guess&nbsp;when&nbsp;the&nbsp;user&nbsp;finishes&nbsp;scrolling.&nbsp;Now&nbsp;I&nbsp;personally&nbsp;don't&nbsp;like&nbsp;using&nbsp;timers&nbsp;for&nbsp;things&nbsp;like&nbsp;this.&nbsp;Any&nbsp;Idea's?If required i can give you the code for detection of the start of the scrolling. I am using&nbsp;

kidd_ip · Answer

How about leveraging System.Windows.Forms.Timer alongside some conditions to determine when the user stops scrolling, without relying purely on timers:
&nbsp;

Hook into the scrolling messages to detect when scrolling starts.
Start a System.Windows.Forms.Timer to check for the scrolling state at intervals.
If no scrolling is detected for a specific duration, consider it as the end of scrolling.

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;

public class ScrollDetector
{
    private const int WM_HSCROLL = 0x0114;
    private const int WM_VSCROLL = 0x0115;
    private const int WM_MOUSEWHEEL = 0x020A;
    private Timer scrollTimer;
    private bool isScrolling;

public ScrollDetector()
    {
        scrollTimer = new Timer();
        scrollTimer.Interval = 100; // Check every 100ms
        scrollTimer.Tick += ScrollTimer_Tick;
        isScrolling = false;

// Set up your hook or message intercept here
    }

private void ScrollTimer_Tick(object sender, EventArgs e)
    {
        if (!isScrolling)
        {
            scrollTimer.Stop();
            OnScrollEnd();
        }
        isScrolling = false;
    }

private void OnScrollEnd()
    {
        // Handle scroll end event
        Console.WriteLine("Scrolling ended");
    }

// Example window procedure to intercept scroll messages
    protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM_HSCROLL || m.Msg == WM_VSCROLL || m.Msg == WM_MOUSEWHEEL)
        {
            isScrolling = true;
            if (!scrollTimer.Enabled)
            {
                scrollTimer.Start();
            }
        }
        base.WndProc(ref m);
    }
}

&nbsp;

jaymcc510 · Answer

Awesome&nbsp;

myexceldeveloper · Answer

Hello,&nbsp;thanks very much for the replay. I did try that already but the thing is it's using timers, so it will not give an event when the user is finished scrolling. To get a 'smooth' result one needs to know when the users stops scrolling otherwise the timer has ended while the user is still scrolling, or the user is already 'long' finished scrolling, and there is the problem. Now catching the PgUP/DN/Arrow keys is not a problem but using the mousewheel or the scrollbars is. Also note that the scrolling event only starts the event when the user starts scrolling so not during scrolling (as far as I know).Tnx Arie&nbsp;

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VSTO Excel Worksheet Scrolling Event

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