.net - 使用 PropertyGrid 设置 PerformanceCounter

Question

我想通过使用 PropertyGrid 设置参数来动态创建一个 PerformanceCounter。如果我将 PropertyGrid.SelectedObject 设置为 PerformanceCounter，它不会提供与 IDE 中相同的选项。

我该怎么做？有可能吗？

Answer 1

主要问题是某些 PerformanceCounter 属性(例如 CategoryName)标有 ReadOnly属性。当属性网格在属性上看到 ReadOnly 属性时，您无法对其进行编辑，因此您无法使用包含类别名称列表的下拉菜单。

我不知道设计师用了什么魔法来克服这个问题，但这是我的解决方案。我们添加自定义 TypeDescriptionProvider到已编辑的 PerformanceCounter 实例，并提供一个自定义类型描述符以消除 ReadOnly 限制。

这是您可以如何使用它(使用 PropertyGrid 类的 propertyGrid1 实例):

PerformanceCounter counter = new PerformanceCounter();

// use a custom type description provider for this counter
TypeDescriptor.AddProvider(new PerformanceCounterTypeProvider(), counter);

// filter unwanted properties
propertyGrid1.BrowsableAttributes = new AttributeCollection(DesignerSerializationVisibilityAttribute.Visible);

// select it in the property grid
propertyGrid1.SelectedObject = counter;

这是使用的实用程序代码:

public class PerformanceCounterTypeProvider : TypeDescriptionProvider
{
    private static PropertyDescriptor[] _properties;

    static PerformanceCounterTypeProvider()
    {
        List < PropertyDescriptor> properties = new List<PropertyDescriptor>();
        foreach (PropertyDescriptor pd in TypeDescriptor.GetProperties(typeof(PerformanceCounter)))
        {
            PerformanceCounterPropertyDescriptor clone = new PerformanceCounterPropertyDescriptor(pd);
            properties.Add(clone);
        }
        _properties = properties.ToArray();
    }

    public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType, object instance)
    {
        return new PerformanceCounterTypeDescriptor();
    }

    private class PerformanceCounterTypeDescriptor : CustomTypeDescriptor
    {
        public override PropertyDescriptorCollection GetProperties(Attribute[] attributes)
        {
            return new PropertyDescriptorCollection(PerformanceCounterTypeProvider._properties.ToArray());
        }
    }

    private class PerformanceCounterPropertyDescriptor : PropertyDescriptor
    {
        private PropertyDescriptor _desc;

        public PerformanceCounterPropertyDescriptor(PropertyDescriptor desc)
            : base(desc, new List<Attribute>(desc.Attributes.OfType<Attribute>()).ToArray())
        {
            _desc = desc;
        }

        public override void SetValue(object component, object value)
        {
            // we can't use _desc.SetValue because the underlying property descriptor checks it's read only
            ComponentType.GetProperty(Name).SetValue(component, value, null);
        }

        public override bool IsReadOnly
        {
            get { return false; }
        }

        public override bool CanResetValue(object component)
        {
            return _desc.CanResetValue(component);
        }

        public override Type ComponentType
        {
            get { return _desc.ComponentType; }
        }

        public override object GetValue(object component)
        {
            return _desc.GetValue(component);
        }

        public override Type PropertyType
        {
            get { return _desc.PropertyType; }
        }

        public override void ResetValue(object component)
        {
            _desc.ResetValue(component);
        }

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