鼠标滚轮会始终影响面板吗？

Question

Not sure if I can word this right but here we go.

I have my application which has a couple of text boxes and a panel with a scroll bar. I want the mouse scroll wheel to always affect the panel. Is there a way of doing this? Currently when I change focus form the panel to the text boxs the scroll wheel stops working for the panel.

Thanks in advance

Answer 1

You can do this with a PreFilterMessage. Firstly, change your form to implement IMessageFilter as in:

public partial class Form1 : Form, IMessageFilter

Then in the constructor add the message filter:

public Form1()
{
  InitializeComponent();
  Application.AddMessageFilter(this);
}

Then implement the IMessageFilter interface:

public bool PreFilterMessage(ref Message m)
{
  if (m.Msg == WM_MOUSEWHEEL)
  {
    SendMessage(panel1.Handle, m.Msg, m.WParam, m.LParam);
    return true;
  }
  return false;
}

And you will also need the following:

private const int WM_MOUSEWHEEL = 0x020A;
[DllImport("user32.dll")]
private static extern IntPtr WindowFromPoint(Point pt);
[DllImport("user32.dll")]
private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);