问题
We have a WinForms application that we are progressively converting to WPF. At this point the application's main form is a Form (WinForms) that contains a vertical sidebar built in WPF. The sidebar is hosted in an ElementHost control.
The sidebar is made of a ScrollViewer that contains other controls. The problem is that when the focus is somewhere in the WinForms aera and I use the mouse wheel over the ScrollViewer, it does not scroll.
This is related to the WPF/WinForms integration because in a 100% WPF project, the ScrollViewer reacts to the mouse wheel even if the focus is on another control.
What is the correct way to fix this?
回答1:
consider doing a message filter and when you receive WM_MOUSEWHEEL, determine if the mouse is over your WPF control. If so then send the message directly to your Element window handle.
Something like this:
System.Windows.Forms.Application.AddMessageFilter( new MouseWheelMessageFilter( YourElementInsideAnElementHost ) );
Dont forget to call RemoveMessageFilter when you go out of scope
public class MouseWheelMessageFilter : IMessageFilter
{
private const int WM_MOUSEWHEEL = 0x020A;
private FrameworkElement _element;
[DllImport("user32.dll")]
public static extern int SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
public MouseWheelMessageFilter(FrameworkElement element)
{
_element = element;
}
public bool PreFilterMessage(ref Message m)
{
if (m.Msg == WM_MOUSEWHEEL)
{
Rect rect = new Rect(0, 0, _element.ActualWidth, _element.ActualHeight);
Point pt = Mouse.GetPosition(_element);
if (rect.Contains(pt))
{
HwndSource hwndSource = (HwndSource)HwndSource.FromVisual(_element);
SendMessage(hwndSource.Handle, m.Msg, m.WParam, m.LParam);
return true;
}
}
return false;
}
}
回答2:
Try setting the focus to the ElementHost by calling elementHost.Select()
This made the MouseWheel event work for me.
来源:https://stackoverflow.com/questions/5723290/mouse-events-are-not-received-by-a-wpf-scrollviewer-when-hosted-in-a-winforms-co