【发布时间】：2020-05-23 08:37:16
【问题描述】：
VB.Net
我有一个带有 Dgv1(DataGridView) 的 UserControl
我想用“编辑列”表单编辑设计中的列
鳕鱼用户控制：
Public Class MyUserControl
Inherits UserControl
<Editor(GetType(MyColumnEditor), GetType(UITypeEditor))> _
<DesignerSerializationVisibility(DesignerSerializationVisibility.Content)> _
Public ReadOnly Property Columns() As DataGridViewColumnCollection
Get
Return Me.Dgv1.Columns
End Get
End Property
End Class
MyColumnEditor：
Public Class MyColumnEditor
Inherits System.Drawing.Design.UITypeEditor
Public Overrides Function GetEditStyle(context As ITypeDescriptorContext) As UITypeEditorEditStyle
Return UITypeEditorEditStyle.Modal
End Function
Public Overloads Overrides Function EditValue(context As ITypeDescriptorContext, provider As IServiceProvider, value As Object) As Object
Dim field As Object = context.Instance.[GetType]().GetField("Dgv1", System.Reflection.BindingFlags.NonPublic Or System.Reflection.BindingFlags.Instance)
Dim dataGridView1 = CType(field.GetValue(context.Instance), DataGridView)
dataGridView1.Site = CType(context.Instance, Control).Site
Dim columnsProperty As Object = TypeDescriptor.GetProperties(dataGridView1)("Columns")
Dim tdc As Object = New TypeDescriptionContext(dataGridView1, columnsProperty)
Dim editor = CType(columnsProperty.GetEditor(GetType(UITypeEditor)), UITypeEditor)
Dim result As Object = editor.EditValue(tdc, provider, value)
dataGridView1.Site = Nothing
Return result
End Function
End Class
TypeDescriptionContext：
Public Class TypeDescriptionContext
Implements ITypeDescriptorContext
Public editingObject As Control
Public editingProperty As PropertyDescriptor
Public Sub New(obj As Control, property1 As PropertyDescriptor)
editingObject = obj
editingProperty = property1
End Sub
Public ReadOnly Property Container As IContainer Implements ITypeDescriptorContext.Container
Get
Return editingObject.Container
End Get
End Property
Public ReadOnly Property Instance As Object Implements ITypeDescriptorContext.Instance
Get
Return editingObject
End Get
End Property
Public Sub OnComponentChanged() Implements ITypeDescriptorContext.OnComponentChanged
End Sub
Public Function OnComponentChanging() As Boolean Implements ITypeDescriptorContext.OnComponentChanging
Return True
End Function
Public ReadOnly Property PropertyDescriptor As PropertyDescriptor Implements ITypeDescriptorContext.PropertyDescriptor
Get
Return editingProperty
End Get
End Property
Public Function GetService(serviceType As Type) As Object Implements IServiceProvider.GetService
Return editingObject.Site.GetService(serviceType)
End Function
End Class
但是当单击列属性进行编辑时显示错误： 未设置对象变量或 With 块变量。
https://i.stack.imgur.com/rkeua.jpg
和
C#中相同的代码：，运行正常
用户控制：
public partial class MyUserControl : UserControl
{
public MyUserControl()
{
InitializeComponent();
}
[Editor(typeof(MyColumnEditor), typeof(UITypeEditor))]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
public DataGridViewColumnCollection Columns
{
get { return this.Dgv1.Columns; }
}
}
MyColumnEditor：
public class MyColumnEditor : UITypeEditor
{
public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context)
{
return UITypeEditorEditStyle.Modal;
}
public override object EditValue(ITypeDescriptorContext context,
IServiceProvider provider, object value)
{
var field = context.Instance.GetType().GetField("Dgv1",
System.Reflection.BindingFlags.NonPublic |
System.Reflection.BindingFlags.Instance);
var dataGridView1 = (DataGridView)field.GetValue(context.Instance);
dataGridView1.Site = ((Control)context.Instance).Site;
var columnsProperty = TypeDescriptor.GetProperties(dataGridView1)["Columns"];
var tdc = new TypeDescriptionContext(dataGridView1, columnsProperty);
var editor = (UITypeEditor)columnsProperty.GetEditor(typeof(UITypeEditor));
var result = editor.EditValue(tdc, provider, value);
dataGridView1.Site = null;
return result;
}
}
TypeDescriptionContext：
public class TypeDescriptionContext : ITypeDescriptorContext
{
private Control editingObject;
private PropertyDescriptor editingProperty;
public TypeDescriptionContext(Control obj, PropertyDescriptor property)
{
editingObject = obj;
editingProperty = property;
}
public IContainer Container
{
get { return editingObject.Container; }
}
public object Instance
{
get { return editingObject; }
}
public void OnComponentChanged()
{
}
public bool OnComponentChanging()
{
return true;
}
public PropertyDescriptor PropertyDescriptor
{
get { return editingProperty; }
}
public object GetService(Type serviceType)
{
return editingObject.Site.GetService(serviceType);
}
}
我知道 Vb.net 而不是专业人士 并将此代码 C# 转换为 VB.net
问题出在哪里？ 提前感谢您的帮助
【问题讨论】：
-
为什么需要转换它？绝大多数 .NET Framework 都是用 C# 编写的，您对此没有任何问题。为什么不直接将 C# 代码编译成 DLL 并像使用任何其他库一样使用它？
-
将所有
... As Object替换为Dim tdc = New TypeDescriptionContext(dataGridView1, columnsProperty)。这些不是（所有）对象类型，例如，tdc是TypeDescriptionContext。有些转换器，当找到var something = somethingelse;时，转换为Dim something As Object = somethingelse，这是错误的。无论如何，我会考虑 @jmcilhinney 告诉你的内容。
标签： vb.net datagridview uitypeeditor