使用PropertyGrid设置PerformanceCounter

Question

我想通过使用PropertyGrid设置参数来动态创建PerformanceCounter。如果我将PropertyGrid.SelectedObject设置为PerformanceCounter，它不会提供与集成开发环境中相同的选项。

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我该怎么做这个戏法呢？这是完全可能的吗？

Answer 1

主要问题是一些PerformanceCounter属性，如CategoryName，是用ReadOnly属性标记的。当属性网格在属性上看到ReadOnly属性时，您无法对其进行编辑，因此您可以使用类别名称列表的下拉列表。

我不知道设计师如何使用魔法来克服这一点，但这是我的解决方案。我们向编辑过的PerformanceCounter实例添加一个自定义TypeDescriptionProvider，并提供一个删除ReadOnly限制的自定义类型描述符。

您可以这样使用它(通过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;

下面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);
        }
    }
}

Answer 2

这会告诉我，默认情况下，propertygrid只会显示那些可以在运行时更改的设置，并且在设计时看到的设置和在运行时看到的设置之间总是存在差异。