在PropertyGrid中设置ReadOnly属性会将所有属性设置为只读 [英] Setting ReadOnly Property in PropertyGrid Sets All Properties Readonly

问题描述

我正在使用PropertyGrid控件来编辑类属性，并且我尝试根据其他属性设置将某些属性设置为只读.

I am using a PropertyGrid control to edit my class properties and I am trying to set certain properties read-only depending on other property settings.

这是我班上的代码:

Imports System.ComponentModel
Imports System.Reflection

Public Class PropertyClass

    Private _someProperty As Boolean = False

    <DefaultValue(False)>
    Public Property SomeProperty As Boolean
        Get
            Return _someProperty
        End Get
        Set(value As Boolean)
            _someProperty = value
            If value Then
                SetReadOnlyProperty("SerialPortNum", True)
                SetReadOnlyProperty("IPAddress", False)
            Else
                SetReadOnlyProperty("SerialPortNum", False)
                SetReadOnlyProperty("IPAddress", True)
            End If
        End Set
    End Property

    Public Property IPAddress As String = "0.0.0.0"

    Public Property SerialPortNum As Integer = 0

    Private Sub SetReadOnlyProperty(ByVal propertyName As String, ByVal readOnlyValue As Boolean)
        Dim descriptor As PropertyDescriptor = TypeDescriptor.GetProperties(Me.GetType)(propertyName)
        Dim attrib As ReadOnlyAttribute = CType(descriptor.Attributes(GetType(ReadOnlyAttribute)), ReadOnlyAttribute)
        Dim isReadOnly As FieldInfo = attrib.GetType.GetField("isReadOnly", (BindingFlags.NonPublic Or BindingFlags.Instance))
        isReadOnly.SetValue(attrib, readOnlyValue)
    End Sub
End Class

这是我用来编辑值的代码:

This is the code I am using to edit the values:

    Dim c As New PropertyClass
    PropertyGrid1.SelectedObject = c

问题在于，当我将SomeProperty设置为True时，什么也没有发生，而当我再次将其设置为False时，它将 all 属性设置为只读.有人可以看到我的代码中的错误吗?

The problem is that when I set SomeProperty to True, nothing happens and when I then set it to False again it sets all properties Read-Only. Can someone see an error in my code?

推荐答案

尝试使用ReadOnly属性装饰所有的类属性:

Try decorating ALL of your class properties with the ReadOnly attribute:

<[ReadOnly](False)> _
Public Property SomeProperty As Boolean
  Get
    Return _someProperty
  End Get
  Set(value As Boolean)
    _someProperty = value
    If value Then
      SetReadOnlyProperty("SerialPortNum", True)
      SetReadOnlyProperty("IPAddress", False)
    Else
      SetReadOnlyProperty("SerialPortNum", False)
      SetReadOnlyProperty("IPAddress", True)
    End If
  End Set
End Property

<[ReadOnly](False)> _
Public Property IPAddress As String = "0.0.0.0"

<[ReadOnly](False)> _
Public Property SerialPortNum As Integer = 0

从以下代码项目中找到它:启用/禁用属性在运行时在PropertyGrid中

Found it from this Code Project: Enabling/disabling properties at runtime in the PropertyGrid

为了使所有这些正常工作，将类的每个属性的ReadOnly属性静态定义为所需的任何值都是很重要的.如果没有，那么在运行时以这种方式更改属性将错误地修改类的每个属性的属性.

In order for all this to work properly, it is important to statically define the ReadOnly attribute of every property of the class to whatever value you want. If not, changing the attribute at runtime that way will wrongly modify the attributes of every property of the class.

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