zhengxuan.zhang
65 lines
2.0 KiB
C#
65 lines
2.0 KiB
C#
using System;
|
|
using System.Drawing;
|
|
using System.Windows.Forms;
|
|
|
|
namespace Scatter
|
|
{
|
|
public static class MouseWheelHandler
|
|
{
|
|
public static void Add(Control ctrl, Action<MouseEventArgs> onMouseWheel)
|
|
{
|
|
if (ctrl == null || onMouseWheel == null)
|
|
throw new ArgumentNullException();
|
|
|
|
var filter = new MouseWheelMessageFilter(ctrl, onMouseWheel);
|
|
Application.AddMessageFilter(filter);
|
|
ctrl.Disposed += (s, e) => Application.RemoveMessageFilter(filter);
|
|
}
|
|
|
|
private class MouseWheelMessageFilter
|
|
: IMessageFilter
|
|
{
|
|
private readonly Control _ctrl;
|
|
private readonly Action<MouseEventArgs> _onMouseWheel;
|
|
|
|
public MouseWheelMessageFilter(Control ctrl, Action<MouseEventArgs> onMouseWheel)
|
|
{
|
|
_ctrl = ctrl;
|
|
_onMouseWheel = onMouseWheel;
|
|
}
|
|
|
|
public bool PreFilterMessage(ref Message m)
|
|
{
|
|
var parent = _ctrl.Parent;
|
|
if (parent != null && m.Msg == 0x20a) // WM_MOUSEWHEEL, find the control at screen position m.LParam
|
|
{
|
|
var pos = new Point(m.LParam.ToInt32() & 0xffff, m.LParam.ToInt32() >> 16);
|
|
|
|
var clientPos = _ctrl.PointToClient(pos);
|
|
|
|
if (_ctrl.ClientRectangle.Contains(clientPos)
|
|
&& ReferenceEquals(_ctrl, parent.GetChildAtPoint(parent.PointToClient(pos))))
|
|
{
|
|
var wParam = m.WParam.ToInt32();
|
|
Func<int, MouseButtons, MouseButtons> getButton =
|
|
(flag, button) => ((wParam & flag) == flag) ? button : MouseButtons.None;
|
|
|
|
var buttons = getButton(wParam & 0x0001, MouseButtons.Left)
|
|
| getButton(wParam & 0x0010, MouseButtons.Middle)
|
|
| getButton(wParam & 0x0002, MouseButtons.Right)
|
|
| getButton(wParam & 0x0020, MouseButtons.XButton1)
|
|
| getButton(wParam & 0x0040, MouseButtons.XButton2)
|
|
; // Not matching for these /*MK_SHIFT=0x0004;MK_CONTROL=0x0008*/
|
|
|
|
var delta = wParam >> 16;
|
|
var e = new MouseEventArgs(buttons, 0, clientPos.X, clientPos.Y, delta);
|
|
_onMouseWheel(e);
|
|
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
} |