Question

I have an existing Window Forms application. The application has a property grid. The values of the properties are set by the user at runtime. What I would like to do is determine from code the current value of any given property. I have had partial success. I am able to get the Category as well as the property name information. I am having difficulty getting the current value of the properties as set by the user, as well as two other related questions.

The code I am using is as follows:

 // ICustomTypeDescriptor Interface Implementation
 public AttributeCollection GetAttributes()
 {
      return TypeDescriptor.GetAttributes(GetType());
 }

 public string GetClassName()
 {
      return TypeDescriptor.GetClassName(GetType());
 }

 public string GetComponentName()
 {
      return TypeDescriptor.GetComponentName(GetType());
 }

 public TypeConverter GetConverter()
 {
      return TypeDescriptor.GetConverter(GetType());
 }

 public EventDescriptor GetDefaultEvent()
 {
      return TypeDescriptor.GetDefaultEvent(GetType());
 }

 public PropertyDescriptor GetDefaultProperty()
 {
      return TypeDescriptor.GetDefaultProperty(GetType());
 }

 public object GetEditor(Type editorBaseType)
 {
      return TypeDescriptor.GetEditor(GetType(), editorBaseType);
 }

 public EventDescriptorCollection GetEvents(Attribute[] attributes)
 {
      return TypeDescriptor.GetEvents(GetType(), attributes);
 }

 public EventDescriptorCollection GetEvents()
 {
      return TypeDescriptor.GetEvents(GetType());
 }

 public PropertyDescriptorCollection GetProperties(Attribute[] attributes)
 {
      // ... This returns a list of properties.
      PropertyDescriptorCollection pdc = TypeDescriptor.GetProperties(GetType(), attributes);
      PropertyDescriptor[] arr = new PropertyDescriptor[pdc.Count];
      pdc.CopyTo(arr, 0);
      PropertyDescriptorCollection propertyCollection = new PropertyDescriptorCollection(arr);

      ModifyProperties(propertyCollection); // modifies which properties are visible

      // temporary code to get the program to print out the properties
foreach (PropertyDescriptor pd in propertyCollection)
{
           Print("input category = "+pd.Category);
           Print("input display name = "+pd.DisplayName);
           Print("input name = "+pd.Name);
        // Print("input value = "+pd.GetValue(Input).ToString()); <--- Does NOT work
}

return propertyCollection;
 }

 public PropertyDescriptorCollection GetProperties()
 {
      return TypeDescriptor.GetProperties(GetType());
 }

 public object GetPropertyOwner(PropertyDescriptor pd)
 {
      return this;
 }

My questions are:

1. How can I get the values of the properties? For example, I have a property aspect ratio. Its display name is Aspect Ratio and its name is aspectRatio. Its value is 5. How can I retieve this via code at runtime?

2. How can I order the properties. I have tried to use the above approach to ordering the properties but the ordering failed. I am not sure how best to proceed.

Any suggestions would be greatly appreciated. Thank you.

Answer 1

Maybe this

foreach (PropertyDescriptor pd in propertyCollection)
{
     Print("input category = "+pd.Category);
     Print("input display name = "+pd.DisplayName);
     Print("input name = "+pd.Name);
     Print("input value = " + pd.GetValue(GetPropertyOwner(pd)));   
}

If you have custom objects you want to get a nice string from you could add a helper method like below:

    private string GetPropertyValue(PropertyDescriptor pd)
    {
        var property = GetPropertyOwner(pd);
        if (property is CustomObject)
        {
            var dataSeries = property as CustomObject;
            // This will return a string of the list contents ("One, Two, Three")
            return string.Join(",", dataSeries.ListProperty.ToArray());

        }
        else if (property is ....)
        {
            return somthing else
        }
        return property.ToString();
    }

Demo class:

public class CustomObject
{
    private List<string> _listProperty = new List<string>(new string[]{"One","Two","Three"});
    public List<string> ListProperty
    {
        get { return _listProperty; }
        set { _listProperty = value; }
    }

}