Question

我认为这是一个相当基本的问题，但我在这方面的花费时间要远远超过应该花的时间。

上下文如下：

我想创建一个自定义用户控件，它包含一个面板，其中垂直绘制3条线，控件应该以这样的方式工作：当值更改时，控件将使用更新的线位置重新绘制。

到目前为止，我的代码如下：

Public Class ColourValueBar

Private Position_Marker As Integer = 0
Private Position_Marker_LeftBound As Integer = 0
Private Position_Marker_RightBound As Integer = 0

Private render_Marker As Boolean = True
Private render_Left As Boolean = True
Private render_Right As Boolean = True


Private Shared myPenG As Pen = New Pen(Color.Green, 2)
Private Shared myPenM As Pen = New Pen(Color.Magenta, 4)

Public Property Marker() As Integer
    Get
        Return Position_Marker
    End Get
    Set(ByVal value As Integer)
        Try
            If (value < 0 Or value > 255) Then
                Throw New Exception("ColourValueBar : Marker " & value & " is out of bounds")
            End If
            Position_Marker = value
            Refresh()
        Catch ex As Exception
            MessageBox.Show(ex.ToString())
        End Try
    End Set
End Property

Public Property LeftBound() As Integer
    Get
        Return Position_Marker_LeftBound
    End Get
    Set(ByVal value As Integer)
        Try
            If (value < 0 Or value > 255) Then
                Throw New Exception("ColourValueBar : LeftBound " & value & " is out of bounds")
            End If
            Position_Marker_LeftBound = value
            Refresh()
        Catch ex As Exception
            MessageBox.Show(ex.ToString())
        End Try
    End Set
End Property

Public Property RightBound() As Integer
    Get
        Return Position_Marker_RightBound
    End Get
    Set(ByVal value As Integer)
        Try
            If (value < 0 Or value > 255) Then
                Throw New Exception("ColourValueBar : RightBound " & value & " is out of bounds")
            End If
            Position_Marker_RightBound = value
            Refresh()
        Catch ex As Exception
            MessageBox.Show(ex.ToString())
        End Try
    End Set
End Property

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

        ' Add any initialization after the InitializeComponent() call.




    Catch ex As Exception
        MessageBox.Show(ex.ToString())
    End Try

End Sub

Public Sub SetRendering(ByVal marker As Boolean, leftBound As Boolean, rightBound As Boolean)
    Try
        render_Marker = marker
        render_Left = leftBound
        render_Right = rightBound
        Refresh()
    Catch ex As Exception
        MessageBox.Show(ex.ToString())
    End Try
End Sub

'Protected Overridable Sub ColourValueBar_Paint(sender As Object, e As PaintEventArgs)
Public Sub Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs)
    Try
        'Using g As Graphics = PNL_Gradient.CreateGraphics 'Me.CreateGraphics


        If (render_Left) Then
            e.Graphics.DrawLine(myPenM, New Point(Position_Marker_LeftBound, 0), New Point(Position_Marker_LeftBound, 56))
        End If

        If (render_Right) Then
            e.Graphics.DrawLine(myPenM, New Point(Position_Marker_RightBound, 0), New Point(Position_Marker_RightBound, 56))
        End If

        If render_Marker Then
            e.Graphics.DrawLine(myPenG, New Point(Position_Marker, 0), New Point(Position_Marker, 56))
        End If

        '   PNL_Gradient.Refresh()

        ' End Using
    Catch ex As Exception
        MessageBox.Show(ex.ToString())
    End Try


End Sub

我的主要形式的测试代码：

Private Sub frmMain_Load(sender As Object, e As EventArgs) Handles Me.Load
    Try

        Dim Userbox As ColourValueBar = New ColourValueBar()
        Userbox.Location = New Point(150, 145)
        Userbox.Size = New Size(520, 63)
        Userbox.Visible = True


        Me.Controls.Add(Userbox)

        Userbox.Marker = 155
        Userbox.LeftBound = 100
        Userbox.RightBound = 200
        'Userbox.Draw()

    Catch ex As Exception
        MessageBox.Show(ex.ToString())
    End Try
End Sub

问题如下：

我可以从我的主窗体中绘制自定义控件，我可以看到面板。更改值似乎没有做任何事情，我尝试绘制线条的尝试似乎都没有效果。

强制调用Draw（）子函数不会显示任何行，但代码也不会抛出任何错误或异常。

我试过了：

制作一个Draw（）子，我把代码绘制成行并从我的主窗体中调用它
尝试重载Paint（），它会发出自己的警告

我也无法从工具箱中拖放我的控件;并显示错误消息＆＃34;无法加载工具箱项目＆＃39; ColourValueBar＆＃39;。它将从工具箱中删除＆＃39;但以编程方式将其添加到表单似乎有效（据我所知，因为线条图似乎不起作用）

我错过了什么，或者我在做什么本来就错了？

提前致谢，

编辑：

编辑的例程覆盖了OnPaint，在第一次被激活时绘制得很好，但是在线消失的情况下没有正确更新：

 Protected Overrides Sub OnPaint(e As PaintEventArgs)
    Try
        Using g As Graphics = PNL_Gradient.CreateGraphics

＆＃39; MyBase.OnPaint（e）中

            If (render_Left) Then
                g.DrawLine(myPenM, New Point(Position_Marker_LeftBound, 0), New Point(Position_Marker_LeftBound, 56))
            End If

            If (render_Right) Then
                g.DrawLine(myPenM, New Point(Position_Marker_RightBound, 0), New Point(Position_Marker_RightBound, 56))
            End If

            If render_Marker Then
                g.DrawLine(myPenG, New Point(Position_Marker, 0), New Point(Position_Marker, 56))
            End If

            MyBase.OnPaint(e)
        End Using
    Catch ex As Exception
        MessageBox.Show(ex.ToString())
    End Try


End Sub

使用e参数作为抽屉的相同例程，它在外部边界容器上绘制线条，并正确更新，但面板上绘有线条：

    Protected Overrides Sub OnPaint(e As PaintEventArgs)
    Try


        ' MyBase.OnPaint(e)

        If (render_Left) Then

            e.Graphics.DrawLine(myPenM, New Point(Position_Marker_LeftBound, 0), New Point(Position_Marker_LeftBound, 56))
        End If

            If (render_Right) Then
            e.Graphics.DrawLine(myPenM, New Point(Position_Marker_RightBound, 0), New Point(Position_Marker_RightBound, 56))
        End If

            If render_Marker Then
            e.Graphics.DrawLine(myPenG, New Point(Position_Marker, 0), New Point(Position_Marker, 56))
        End If

        MyBase.OnPaint(e)
    Catch ex As Exception
        MessageBox.Show(ex.ToString())
    End Try


End Sub

最后的尝试与＃2的工作方式相同：

   Protected Sub MyPaint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
    Try




        If (render_Left) Then
                e.Graphics.DrawLine(myPenM, New Point(Position_Marker_LeftBound, 0), New Point(Position_Marker_LeftBound, 56))
            End If

            If (render_Right) Then
            e.Graphics.DrawLine(myPenM, New Point(Position_Marker_RightBound, 0), New Point(Position_Marker_RightBound, 56))
        End If

            If render_Marker Then
            e.Graphics.DrawLine(myPenG, New Point(Position_Marker, 0), New Point(Position_Marker, 56))
        End If

    Catch ex As Exception
        MessageBox.Show(ex.ToString())
    End Try


End Sub

VB.net / VS2017 - 在自定义用户控件内的面板上绘制线条

0 个答案: