如何设置非活动控件的背景颜色

Question

我有一个包含多个文本框和组合框的表单。我已将活动控件的背景颜色属性设置为天蓝色。我想在所有文本框和组合框不活动时将它们的背景颜色设置为白色。

Answer 1

有正确的方法和错误的方法。你在问错误的方法。正确的方法是从 TextBox 派生您自己的类并覆盖 OnEnter 和 OnLeave 方法。对 ComboBox 重复此操作。

但是您要求的方式错误，并且您可能尝试添加此功能为时已晚，因此我们必须通过在运行时找到控件来解决它。将构造函数添加到您的表单类并使其看起来像：

Public Sub New()
    InitializeComponent()
    FindControls(Me.Controls)
End Sub

Private Sub FindControls(ctls As Control.ControlCollection)
    For Each ctl As Control In ctls
        Dim match As Boolean
        If TypeOf ctl Is TextBoxBase Then match = True
        If TypeOf ctl Is ComboBox Then
            Dim combo = DirectCast(ctl, ComboBox)
            If combo.DropDownStyle <> ComboBoxStyle.DropDownList Then match = True
        End If
        If match Then
            AddHandler ctl.Enter, AddressOf ControlEnter
            AddHandler ctl.Leave, AddressOf ControlLeave
        End If
        FindControls(ctl.Controls)
    Next
End Sub

Private controlColor As Color

Private Sub ControlEnter(sender As Object, e As EventArgs)
    Dim ctl = DirectCast(sender, Control)
    controlColor = ctl.BackColor
    ctl.BackColor = Color.AliceBlue
End Sub

Private Sub ControlLeave(sender As Object, e As EventArgs)
    Dim ctl = DirectCast(sender, Control)
    ctl.BackColor = controlColor
End Sub