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C# 如何根据 propertygrid 中另一个属性的值公开一个属性?

转载 作者:行者123 更新时间:2023-11-30 16:31:45 24 4
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我有一个具有多个属性的类。有时可以在属性网格中编辑属性 (A)。但有时属性 A 可能无法编辑。这取决于另一个属性的值。

我该怎么做?

编辑:抱歉,我忘了在设计时提到我想要这个。

最佳答案

运行时属性模型是一个高级主题。对于 PropertyGrid,最简单的方法是编写一个 TypeConverter,继承自 ExpandableObjectConverter。覆盖 GetProperties,并将有问题的属性换成自定义属性。

从头开始编写 PropertyDescriptor 是一件苦差事;但在这种情况下,您主要只需要将所有方法链接(“装饰器”)到原始(反射)描述符。只需重写 IsReadOnly 即可返回您想要的 bool 值。

绝非微不足道,而是可以实现的。


using System;
using System.ComponentModel;
using System.Windows.Forms;
static class Program
{
[STAThread]
static void Main() {
Application.EnableVisualStyles();
Application.Run(new Form { Text = "read only",
Controls = {
new PropertyGrid { Dock = DockStyle.Fill, SelectedObject = new Foo { IsBarEditable = false }}
}
});
Application.Run(new Form { Text = "read write",
Controls = {
new PropertyGrid { Dock = DockStyle.Fill, SelectedObject = new Foo { IsBarEditable = true }}
}
});
}

}

[TypeConverter(typeof(Foo.FooConverter))]
class Foo
{
[Browsable(false)]
public bool IsBarEditable { get; set; }
public string Bar { get; set; }
private class FooConverter : ExpandableObjectConverter
{
public override PropertyDescriptorCollection GetProperties(ITypeDescriptorContext context, object value, Attribute[] attributes)
{
var props = base.GetProperties(context, value, attributes);
if (!((Foo)value).IsBarEditable)
{ // swap it
PropertyDescriptor[] arr = new PropertyDescriptor[props.Count];
props.CopyTo(arr, 0);
for (int i = 0; i < arr.Length; i++)
{
if (arr[i].Name == "Bar") arr[i] = new ReadOnlyPropertyDescriptor(arr[i]);
}
props = new PropertyDescriptorCollection(arr);
}
return props;
}
}
}
class ReadOnlyPropertyDescriptor : ChainedPropertyDescriptor
{
public ReadOnlyPropertyDescriptor(PropertyDescriptor tail) : base(tail) { }
public override bool IsReadOnly
{
get
{
return true;
}
}
public override void SetValue(object component, object value)
{
throw new InvalidOperationException();
}
}
abstract class ChainedPropertyDescriptor : PropertyDescriptor
{
private readonly PropertyDescriptor tail;
protected PropertyDescriptor Tail { get {return tail; } }
public ChainedPropertyDescriptor(PropertyDescriptor tail) : base(tail)
{
if (tail == null) throw new ArgumentNullException("tail");
this.tail = tail;
}
public override void AddValueChanged(object component, System.EventHandler handler)
{
tail.AddValueChanged(component, handler);
}
public override AttributeCollection Attributes
{
get
{
return tail.Attributes;
}
}
public override bool CanResetValue(object component)
{
return tail.CanResetValue(component);
}
public override string Category
{
get
{
return tail.Category;
}
}
public override Type ComponentType
{
get { return tail.ComponentType; }
}
public override TypeConverter Converter
{
get
{
return tail.Converter;
}
}
public override string Description
{
get
{
return tail.Description;
}
}
public override bool DesignTimeOnly
{
get
{
return tail.DesignTimeOnly;
}
}
public override string DisplayName
{
get
{
return tail.DisplayName;
}
}
public override PropertyDescriptorCollection GetChildProperties(object instance, Attribute[] filter)
{
return tail.GetChildProperties(instance, filter);
}
public override object GetEditor(Type editorBaseType)
{
return tail.GetEditor(editorBaseType);
}
public override object GetValue(object component)
{
return tail.GetValue(component);
}
public override bool IsBrowsable
{
get
{
return tail.IsBrowsable;
}
}
public override bool IsLocalizable
{
get
{
return tail.IsLocalizable;
}
}
public override bool IsReadOnly
{
get { return tail.IsReadOnly; }
}
public override string Name
{
get
{
return tail.Name;
}
}
public override Type PropertyType
{
get { return tail.PropertyType; }
}
public override void RemoveValueChanged(object component, EventHandler handler)
{
tail.RemoveValueChanged(component, handler);
}
public override void ResetValue(object component)
{
tail.ResetValue(component);
}
public override void SetValue(object component, object value)
{
tail.SetValue(component, value);
}
public override bool ShouldSerializeValue(object component)
{
return tail.ShouldSerializeValue(component);
}
public override bool SupportsChangeEvents
{
get
{
return tail.SupportsChangeEvents;
}
}
}

关于C# 如何根据 propertygrid 中另一个属性的值公开一个属性?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/4692365/

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