如何使控件正确绘制/刷新

我有一个源自支票簿的控件，我将其称为“SettingBooleanButton”，但是当将任何窗口或对话框拖动到该控件上时，该控件会保留拖动的迹象

下图显示了将应用程序窗口拖动到控件上方的效果

这是我的 OnPaint() 代码块

Public Class SettingBooleanButton
    Inherits CheckBox

    Private _settingSection As String
    Private _settingName As String
    Private _associatedSetting As Setting

    Public Event StateChange(ByVal affectedSetting As Setting)

    Sub New()
        ' This call is required by the designer.
        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.
        Appearance = Appearance.Button
        FlatStyle = FlatStyle.Flat
        TextAlign = ContentAlignment.MiddleCenter
        AutoSize = False
    End Sub

    Public Property SettingSection As String
        Get
            Return _settingSection
        End Get
        Set(value As String)
            _settingSection = value
        End Set
    End Property

    Public Property SettingName As String
        Get
            Return _settingName
        End Get
        Set(value As String)
            _settingName = value
        End Set
    End Property

    ''' <summary>
    ''' Sets a boolean value to indicate the initial checked state of the control.
    ''' </summary>
    ''' <value>
    '''   <c>true</c> to set it as [checked state]; otherwise, <c>false</c>.
    ''' </value>
    Public Property CheckedState As Boolean
        Get
            Return Checked
        End Get
        Set(value As Boolean)
            _associatedSetting = New Setting(_settingSection, _settingName, String.Empty)

            RemoveHandler CheckedChanged, AddressOf StateChanged
            Checked = value
            SetText()
            AddHandler CheckedChanged, AddressOf StateChanged
        End Set
    End Property

    Private Sub StateChanged(sender As Object, e As EventArgs)
        If IsNothing(_associatedSetting) Then
            Return
        End If

        _associatedSetting.Value = Checked.ToString()
        SetText()
        RaiseEvent StateChange(_associatedSetting)
    End Sub

    Public Sub SetText()
        If Checked Then
            Font = New Font(Font.FontFamily, Font.Size, FontStyle.Bold)
            ForeColor = Color.WhiteSmoke
            Text = Resource.SettingBooleanButton_TrueState
        Else
            Font = New Font(Font.FontFamily, Font.Size, FontStyle.Regular)
            ForeColor = SystemColors.ControlText
            Text = Resource.SettingBooleanButton_FalseState
        End If
    End Sub

    Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
        MyBase.OnPaint(e)

        If Checked Then
            ControlPaint.DrawBorder(e.Graphics, e.ClipRectangle, Color.Black, ButtonBorderStyle.Solid)               
        End If
    End Sub

End Class

   ControlPaint.DrawBorder(e.Graphics, e.ClipRectangle, ...)

像这样使用 e.ClipRectangle 是 Paint 事件处理程序中的一个传统错误。这是not与您要绘制的边框相匹配的矩形。这只是控制的一部分needs被画。这通常是整个控制，但并非总是如此。例如，当您在控件上拖动窗口时，只有显示的部分需要重新绘制。所以现在你把边框画在了错误的位置，产生了那些黑线。

仅当您的绘制代码很昂贵并且您想趁机在不需要时跳过该昂贵的代码时，您才使用 ClipRectangle。这是非常罕见的，Windows 中的剪辑已经非常高效了。

您需要传递边框的实际矩形。使固定：

   ControlPaint.DrawBorder(e.Graphics, Me.ClientRectangle, _
                           Color.Black, ButtonBorderStyle.Solid)