如果我有一个winform,我是否可以通过使用Ctrl鼠标滚轮来知道如何控制应用程序中的字体缩放级别(以及应用程序窗口本身)？我看到Scroll Wheel事件中有一个Delta,但不确定它是如何工作的.有没有我可以研究的代码示例？
非常感谢所有的帮助！
您必须处理
KeyDown和
KeyUp事件才能确定是否按住Ctrl键.此值应存储在类级别,因为除了KeyDown和KeyUp事件之外,其他子例程将使用它.
然后编写代码来处理表单的MouseWheel事件.向下滚动(朝向您)会导致MouseEventArgs的Delta属性为负值.向上滚动显然是相反的. Delta属性的值始终为120.
微软的这个价值的原因如下：
Currently,a value of 120 is the standard for one detent. If higher resolution mice are introduced,the definition of WHEEL_DELTA might become smaller. Most applications should check for a positive or negative value rather than an aggregate total.
在您的上下文中,您只需检查Delta的符号并执行操作.
Public Class Form1
Enum ZoomDirection
None
Up
Down
End Enum
Dim CtrlIsDown As Boolean
Dim ZoomValue As Integer
Sub New()
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
ZoomValue = 100
End Sub
Private Sub Form1_KeyDown_KeyUp(ByVal sender As Object,_
ByVal e As KeyEventArgs) _
Handles Me.KeyDown,Me.KeyUp
CtrlIsDown = e.Control
End Sub
Private Sub Form1_MouseWheel(ByVal sender As Object,ByVal e As MouseEventArgs) _
Handles Me.MouseWheel
'check if control is being held down
If CtrlIsDown Then
'evaluate the delta's sign and call the appropriate zoom command
Select Case Math.Sign(e.Delta)
Case Is < 0
Zoom(ZoomDirection.Down)
Case Is > 0
Zoom(ZoomDirection.Up)
Case Else
Zoom(ZoomDirection.None)
End Select
End If
End Sub
Private Sub Zoom(ByVal direction As ZoomDirection)
'change the zoom value based on the direction passed
Select Case direction
Case ZoomDirection.Up
ZoomValue += 1
Case ZoomDirection.Down
ZoomValue -= 1
Case Else
'do nothing
End Select
Me.Text = ZoomValue.ToString()
End Sub
End Class
有关您的问题的更多信息,请阅读以下内容：
> MSDN: Control.KeyDown Event
> MSDN: Control.KeyUp Event
> MSDN: Control.MouseWheel Event
> MSDN: MouseEventArgs Class