自定义边框在WPF标签 [英] Custom Border in a WPF Label

问题描述

我需要建立一个自定义的WPF控件这样的事情

I need to build a custom WPF Control something like this

由于我是新WPF中，我用下面的code（对不起，VB.NET）

As I am new in WPF, I used the following code (sorry for VB.NET)

Public Class TextPlaceholder
  Inherits System.Windows.Controls.Label

  Const CustomBorderWidth As Integer = 2

  Public Sub New()
    MyBase.New()
    Me.BorderBrush = SystemColors.ActiveBorderBrush
  End Sub

  Protected Overrides Sub OnRender(drawingContext As System.Windows.Media.DrawingContext)
    MyBase.OnRender(drawingContext)

    Dim pointTopLeft As New Point(-1, -1)
    Dim pointTopRight As New Point(Me.ActualWidth, -1)
    Dim pointBottomLeft As New Point(-1, Me.ActualHeight)
    Dim pointBottomRight As New Point(Me.ActualWidth, Me.ActualHeight)

    Dim myPen As New Pen(Me.BorderBrush, CustomBorderWidth)
    drawingContext.DrawLine(myPen, pointTopLeft, New Point(pointTopLeft.X + 5, pointTopLeft.Y))
    drawingContext.DrawLine(myPen, pointTopLeft, New Point(pointTopLeft.X, pointTopLeft.Y + 5))

    drawingContext.DrawLine(myPen, pointTopRight, New Point(pointTopRight.X - 5, pointTopRight.Y))
    drawingContext.DrawLine(myPen, pointTopRight, New Point(pointTopRight.X, pointTopRight.Y + 5))

    drawingContext.DrawLine(myPen, pointBottomLeft, New Point(pointBottomLeft.X + 5, pointBottomLeft.Y))
    drawingContext.DrawLine(myPen, pointBottomLeft, New Point(pointBottomLeft.X, pointBottomLeft.Y - 5))

    drawingContext.DrawLine(myPen, pointBottomRight, New Point(pointBottomRight.X - 5, pointBottomRight.Y))
    drawingContext.DrawLine(myPen, pointBottomRight, New Point(pointBottomRight.X, pointBottomRight.Y - 5))
  End Sub

End Class

现在

1）是否有做到这一点的最好办法，考虑到我将继承该控件，需要在继承的控制相同的边框
2）这是好以指定BorderBrush的默认值（是不透明的），像我一样？
3）为什么我的角落都动了一个像素（不是很合适链接）？

1) Is it the best way to do it, considering that I will inherit that control and need the same border on the inherited controls
2) Is it good to specify the default value for the BorderBrush (to be non-transparent), like I did?
3) Why my corners are moved with a pixel (not really right linked)?

推荐答案

一个更好的事情是不是使用了边框类/控制创建自己的装饰类（这基本上是什么边框是）。

A better thing to do is instead of using the Border class/control create your own Decorator class (that's essentially what a Border is).

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