How to modify PropertyGrid at runtime (add/remove property and dynamic types/enums)

Question

How do you modify a propertygrid at runtime in every way? I want to be able to add and remove properties and add "dynamic types", what I mean with that is a type that result in a runtime generated dropdown in the propertygrid using a TypeConverter.

I have actually been able to do both those things (add/remove properties and add dynamic type) but only separately not at the same time.

To implement the support to add and remove properties at runtime I used this codeproject article and modified the code a bit to support different types (not just strings).

private System.Windows.Forms.PropertyGrid propertyGrid1;
private CustomClass myProperties = new CustomClass();

public Form1()
{
    InitializeComponent();

    myProperties.Add(new CustomProperty("Name", "Sven", typeof(string), false, true));
    myProperties.Add(new CustomProperty("MyBool", "True", typeof(bool), false, true));
    myProperties.Add(new CustomProperty("CaptionPosition", "Top", typeof(CaptionPosition), false, true));
    myProperties.Add(new CustomProperty("Custom", "", typeof(StatesList), false, true)); //<-- doesn't work
}

/// <summary>
/// CustomClass (Which is binding to property grid)
/// </summary>
public class CustomClass: CollectionBase,ICustomTypeDescriptor
{
    /// <summary>
    /// Add CustomProperty to Collectionbase List
    /// </summary>
    /// <param name="Value"></param>
    public void Add(CustomProperty Value)
    {
        base.List.Add(Value);
    }

    /// <summary>
    /// Remove item from List
    /// </summary>
    /// <param name="Name"></param>
    public void Remove(string Name)
    {
        foreach(CustomProperty prop in base.List)
        {
            if(prop.Name == Name)
            {
                base.List.Remove(prop);
                return;
            }
        }
    }

etc...

public enum CaptionPosition
{
    Top,
    Left
}

My complete solution can be downloaded here.

It works fine when I add strings, bools or enums, but when I try to add a "dynamic type" like StatesList it doesn't work. Does anyone know why and can help me to solve it?

public class StatesList : System.ComponentModel.StringConverter
{
    private string[] _States = { "Alabama", "Alaska", "Arizona", "Arkansas" };

    public override System.ComponentModel.TypeConverter.StandardValuesCollection
    GetStandardValues(ITypeDescriptorContext context)
    {
        return new StandardValuesCollection(_States);
    }

    public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
    {
        return true;
    }

    public override bool GetStandardValuesExclusive(ITypeDescriptorContext context)
    {
        return true;
    }
}

The method of using a TypeConverter works fine when you don't try to add the property at runtime, for example this code works without any problem, but I want to be able to do both.

Please take a look at my project. Thanks!

Answer 1

What you do, is adding StatesList (a TypeConverter) as a property.
What you should do, is adding a property with StatesList as its TypeConverter.

Answer 2

Ah, of course!

myProperties.Add(new CustomProperty("Custom", "", typeof(States), false, true));

[TypeConverter(typeof(StatesList))]
public class States
{
}

Works like a charm, thank you!

I have updated my project, hope it can be helpful to others, it can be found here.

Answer 3

This question and answer was of great usefulness to me. However, I needed to extend things a bit further by allowing for run-time generated dropdown list values. I thought I would post some sample code in regards to what it required, in case anyone finds it useful.

First, I added an options parameter to the CustomProperty constructor and added an Options property:

    private List<string> lOptions;

    public CustomProperty(string sName, object value, Type tType, bool bReadOnly, bool bVisible, List<string> lOptions)
    {
        this.lOptions = lOptions;
    }

    public List<string> Options
    {
        get { return lOptions; }
    }

Second, I added an Options property to the CustomPropertyDescriptor class:

    public List<string> Options
    {
        get
        {
            return m_Property.Options;
        }
    }

Third, I had to modify the GetStandardValues method in my dynamic type class (i.e. StatesList) to make use of the new Options property on the CustomPropertyDescriptor Object:

    public override StandardValuesCollection
                 GetStandardValues(ITypeDescriptorContext context)
    {
        CustomPropertyDescriptor descriptor = (CustomPropertyDescriptor)context.PropertyDescriptor;
        return new StandardValuesCollection(descriptor.Options);
    }

Finally, I had to pass in my list of options when creating a new CustomProperty object:

    List<string> optionsList = new List<string>(new string[] { "test1", "test2", "test3" });        
    CustomProperty myProperty = new CustomProperty(attr.Name, attr.Value, valueType, false, true, optionsList);

In place of the static list that I passed in for this example, you can generate the list of options for your dropdown in any manner that you please, giving you full control over the options available.

Answer 4

in my case TypeConverter did not apply to States class

[TypeConverter(typeof(StatesList))] // not work
public class States
{
}

so i added override in CustomPropertyDescriptor

public override TypeConverter Converter
{
    get {
        if (this.PropertyType.Equals(typeof(States)) ) {
            return new StatesList(); ; 
        }
        return base.Converter;
    }
}