VB.Net程序设计:鼠标滑轮滚动Panel面板

http://www.vbforums.com/showthread.PHP?646751-Scrolling-a-panel-with-mousewheel

Scrolling a panel with mousewheel.

If the panel is hosted on a form,you Could handle the form's MouseWheel event to scroll the panel like this:

Code:

Private Sensitivity As Integer = 20

Private Sub Panel1_MouseWheel(sender As Object,e As System.Windows.Forms.MouseEventArgs) Handles Panel1.MouseWheel
	If Panel1.Bounds.Contains(e.Location) Then
		Dim vScrollPosition As Integer = Panel1.VerticalScroll.Value
		vScrollPosition -= Math.Sign(e.Delta) * Sensitivity
		vScrollPosition = Math.Max(0,vScrollPosition)
		vScrollPosition = Math.Min(vScrollPosition,Me.VerticalScroll.Maximum)
		Panel1.AutoScrollPosition = New Point(Panel1.AutoScrollPosition.X,_
                              vScrollPosition)
		Panel1.Invalidate()
	End If
End Sub

Edit: The panel's own MouseWheel event fires only when the panel has Focus. So another way is to make a control which inherits from Panel:

Code:

Public Class PanelWithWheelScrolling
	Inherits Panel
	Protected Overrides Sub OnMouseEnter(e As System.EventArgs)
		Me.Select()
		MyBase.OnMouseEnter(e)
	End Sub
End Class

However,I haven't found a way yet to make the panel lose focus when the mouse leaves it,which Could be a nuisance if you don't want it to scroll. Maybe someone else can think of a way.

Edit 2: An option is to pass the focus to a sibling control,but you should do it on the parent Form rather than in an inherited control as above:

Code:

Private Sub Panel1_MouseEnter(sender As Object,e As System.EventArgs) Handles Panel1.MouseEnter
		Panel1.Select()
	End Sub

	Private Sub Panel1_MouseLeave(sender As Object,e As System.EventArgs) Handles Panel1.MouseLeave
		Button1.Select()
	End Sub

At least the code is a bit simpler than my first version! BB