如何在运行时更改DisplayNameAttribute以在Property Grid C#中使用

Question

我想知道如何在运行时更改DisplayNameAttribute,当我进行一些转换时,我希望displayName在我的属性网格中是Feet而不是Meters,这可能吗？

[DisplayName("Meters")]
public double Distance
  {
     get{return distance;}
  }

Answer 1

有许多不同的方法可以做到这一点.最简单的是做一些类似于某些i18n产品的做法 - 将属性子类化并截取文本; 但这仅在您拥有类型时才有效,并且从属性中您无法访问上下文.

接下来要看的是TypeConverter,因为它提供了对属性的组件模型视图的访问,并且比下两个选项更简单;-p这将适用于PropertyGrid,但不是DataGridView等等.

列表中的下一个是ICustomTypeDescriptor- 不是一个有趣的实现接口,但您可以交换自己的属性描述符.这要求您拥有该类型(以提供接口支持).

最后,CustomTypeDescriptor就像最后一样,但即使对于你不拥有的类型也是如此,并允许在类型和对象级别访问调整的元数据(其他一切只支持对象).

选择哪个？我怀疑那TypeConverter是最明智的; 你需要对象上下文(子类属性不提供),但你不需要额外的复杂性.

这是一个例子; 请注意,在TypeConverter代码中我们可以访问对象上下文.如果名称很简单,那么将其放入TypeConverter(创建属性时)就足够了.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows.Forms;
class MyFunkyTypeConverter : ExpandableObjectConverter
{
    public override PropertyDescriptorCollection GetProperties(ITypeDescriptorContext context, object value, Attribute[] attributes)
    {
        PropertyDescriptorCollection props = base.GetProperties(context, value, attributes);
        List<PropertyDescriptor> list = new List<PropertyDescriptor>(props.Count);
        foreach (PropertyDescriptor prop in props)
        {
            switch (prop.Name)
            {
                case "Distance":
                    list.Add(new DisplayNamePropertyDescriptor(
                        prop, "your magic code here"));
                    break;
                default:
                    list.Add(prop);
                    break;
            }
        }
        return new PropertyDescriptorCollection(list.ToArray(), true);
    }
}
class DisplayNamePropertyDescriptor : PropertyDescriptor
{
    private readonly string displayName;
    private readonly PropertyDescriptor parent;
    public DisplayNamePropertyDescriptor(
        PropertyDescriptor parent, string displayName) : base(parent)
    {
        this.displayName = displayName;
        this.parent = parent;
    }
    public override string  DisplayName
    {get { return displayName; } }

    public override bool ShouldSerializeValue(object component)
    { return parent.ShouldSerializeValue(component); }

    public override void SetValue(object component, object value) {
        parent.SetValue(component, value);
    }
    public override object GetValue(object component)
    {
        return parent.GetValue(component);
    }
    public override void ResetValue(object component)
    {
        parent.ResetValue(component);
    }
    public override bool CanResetValue(object component)
    {
        return parent.CanResetValue(component);
    }
    public override bool IsReadOnly
    {
        get { return parent.IsReadOnly; }
    }
    public override void AddValueChanged(object component, EventHandler handler)
    {
        parent.AddValueChanged(component, handler);
    }
    public override void RemoveValueChanged(object component, EventHandler handler)
    {
        parent.RemoveValueChanged(component, handler);
    }
    public override bool SupportsChangeEvents
    {
        get { return parent.SupportsChangeEvents; }
    }
    public override Type PropertyType
    {
        get { return parent.PropertyType; }
    }
    public override TypeConverter Converter
    {
        get { return parent.Converter; }
    }
    public override Type ComponentType
    {
        get { return parent.ComponentType; }
    }
    public override string Description
    {
        get { return parent.Description; }
    }
    public override PropertyDescriptorCollection GetChildProperties(object instance, Attribute[] filter)
    {
        return parent.GetChildProperties(instance, filter);
    }
    public override string Name
    {
        get { return parent.Name; }
    }

}

[TypeConverter(typeof(MyFunkyTypeConverter))]
class MyFunkyType
{
    public double Distance {get;set;}

    public double AnotherProperty { get; set; }
}
static class Program
{
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.Run(new Form { Controls = {
            new PropertyGrid { Dock = DockStyle.Fill,
                SelectedObject = new MyFunkyType {
                    Distance = 123.45
                }}
        }});
    }
}