Question

这是我的代码，应该改变我的任何按钮的背面颜色，但它不起作用，我不知道什么是错的：

Public Sub color(ByVal backcolor As System.Drawing.Color)
    backcolor = Drawing.Color.CadetBlue
End Sub

以下是点击按钮时的调用方法。它应该改变Button1的背面颜色，但它不会。我做得对吗还是我错过了什么？

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    color(Button1.BackColor)
End Sub

Answer 1

System.Drawing.Color是值类型（结构）。当您将其传递给color方法时，只会传递一个副本，并且您的方法只会更改副本。您应该将Sub更改为Function并返回颜色并将其指定给按钮的BackColor属性：

Public Function color() As System.Drawing.Color
    Return System.Drawing.Color.CadetBlue
End Function

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    Button1.BackColor = color()
End Sub

虽然该功能不会添加任何值。你应该直接设置颜色：

Button1.BackColor = System.Drawing.Color.CadetBlue

Per @ VisualVincent的评论，你可以在你的Sub：

中使用ByRef

Private Sub ChangeColor(ByRef c As System.Drawing.Color)
    c = Color.CadetBlue
End Sub

Answer 2

Public Sub color(ByVal btn As Control, ByVal clr As System.Drawing.Color)
    btn.BackColor = clr
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    color(Button1, Drawing.Color.CadetBlue)
End Sub

或者

Public Sub color(ByVal btn As Control)
    btn.BackColor = Drawing.Color.CadetBlue
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    color(Button1)
End Sub

适用于任何控件（Textboxes，Labels e.t.c）

Answer 3

您可以创建一个扩展方法来执行此操作。创建公共模块，如下所示：

Public Module Module1    
    <Runtime.CompilerServices.Extension()>
    Public Sub SetBackColourToCadetBlue(aButton As Button)
    'Use the following line for Telerik Button
    'Public Sub SetBackColourToCadetBlue(aButton As Telerik.WinControls.UI.RadButton) 
        aButton.BackColor = Color.CadetBlue
    End Sub
End Module

您可以调用以下内容来设置任何按钮的背景颜色：

Button1.SetBackColourToCadetBlue()

无法通过自定义方法更改按钮的背景颜色

3 个答案: