vb.net - 在用户控件中单击属性时打开“编辑列”时出错
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
我的专栏编辑器:
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
类型描述上下文:
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:对象变量或未设置块变量。
https://i.stack.imgur.com/rkeua.jpg
和
C#中的相同代码: ,它可以正常工作
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; }
}
}
我的专栏编辑器:
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;
}
}
类型描述上下文:
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
哪里有问题?在此先感谢您的帮助
解决方案
我发现了问题
在 VB.Net 中,当在 Designer Cod 中将 Datagridview 添加到 UserControl 时定义有:
Friend WithEvents Dgv1 As System.Windows.Forms.DataGridView
这是正确的
Private Dgv1 As System.Windows.Forms.DataGridView
甚至不应该那样
Private WithEvents Dgv1 As System.Windows.Forms.DataGridView
这太糟糕了
我决定转向 C#
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