AttributeCallback 委托
更新：2007 年 11 月
在某一类型需要属性时调用。
命名空间： Microsoft.Windows.Design.Metadata
程序集： Microsoft.Windows.Design（在 Microsoft.Windows.Design.dll 中）
语法
声明
Public Delegate Sub AttributeCallback ( _
builder As AttributeCallbackBuilder _
)
用法
Dim instance As New AttributeCallback(AddressOf HandlerMethod)
public delegate void AttributeCallback(
AttributeCallbackBuilder builder
)
public delegate void AttributeCallback(
AttributeCallbackBuilder^ builder
)
JScript 不支持委托。
参数
builder
类型：Microsoft.Windows.Design.Metadata.AttributeCallbackBuilder可用于添加属性的 AttributeCallbackBuilder。AttributeCallbackBuilder 委托只能为请求元数据的类型生成属性。
备注
在填充较大的属性表时，可以使用 AttributeCallback 委托。通过使用回调模式，可将属性表填充一直推迟到设计器需要某一类型的设计时元数据时。
示例
下面的代码示例演示如何使用 AttributeCallbackBuilder 类创建和填充属性表。
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.ComponentModel;
using System.Reflection;
using System.Windows.Media;
using System.Windows.Controls;
using System.Windows;
using Microsoft.Windows.Design.Features;
using Microsoft.Windows.Design.Metadata;
namespace CustomControlLibrary.VisualStudio.Design
{
// Container for any general design-time metadata to initialize.
// Designers look for a type in the design-time assembly that
// implements IRegisterMetadata. If found, designers instantiate
// this class and call its Register() method automatically.
internal class Metadata : IRegisterMetadata
{
// Called by the designer to register any design-time metadata.
public void Register()
{
AttributeTableBuilder builder = new AttributeTableBuilder();
// Build the attribute table by using the AttributeCallbackBuilder
// class. The attribute table is not populated until the designer
// needs it, which is more efficient for large attribute tables.
builder.AddCallback(
typeof(Button),
delegate(AttributeCallbackBuilder callbackBuilder)
{
callbackBuilder.AddCustomAttributes(
new DefaultPropertyAttribute("Content"));
// Apply the ReadOnlyAttribute to the Background property
// of the Button class.
callbackBuilder.AddCustomAttributes(
"Background",
new ReadOnlyAttribute(true));
PropertyDescriptorCollection properties =
TypeDescriptor.GetProperties(typeof(Button));
PropertyDescriptor pd = properties["Foreground"];
callbackBuilder.AddCustomAttributes(
pd,
new ReadOnlyAttribute(true));
callbackBuilder.AddCustomAttributes(
Button.WidthProperty,
new TypeConverterAttribute(typeof(LengthConverter)),
new DescriptionAttribute("This is the width"));
MemberInfo[] members = typeof(Button).GetMember("Height");
callbackBuilder.AddCustomAttributes(
members[0],
new ReadOnlyAttribute(true));
});
MetadataStore.AddAttributeTable(builder.CreateTable());
}
}
}
另请参见
参考
Microsoft.Windows.Design.Metadata 命名空间