Office Development

PInvoke Object Extender

David E. CraigLeave a comment

If you have done work in Office (especially Excel) and performed operations that look across all the cells in the UsedRange, you might note – if you do a performance analysis of your code – that you will see up to 100ms per Object Model touch, especially for properties and methods from the Cell object. The issue here are all the checks and balances in the Primary Interops as well as the weight of .NET through COM. To avoid it you can Private Invoke (PInvoke) the Excel application directly and .NET does two things for you:

  1. It keeps the function table for the private interface cached so it does not always have to keep going and getting it for you.
  2. It allows you to interface with the EXE directly, bypassing several layers.

The end result, is usually something like a 100ms to 3ms performance improvement.

To help with PInvoke operations, I developed the following class that EXTENDS the OBJECT class type:

/// <summary>
/// This class extends object with a set of methods to help
/// PInvoke into COM objects much faster.
/// </summary>
public static class ObjectExtender
{
    public static object InvokeMethod(this object PobjItem, string PstrMethod, object[] PobjMethodParams)
    {
        try
        {
            return PobjItem.GetType().InvokeMember(PstrMethod, BindingFlags.InvokeMethod, null, PobjItem, PobjMethodParams, null);
        }
        catch
        {
            return null;
        }

    }

    public static object InvokeMethod(this object PobjItem, string PstrMethod)
    {
        return InvokeMethod(PobjItem, PstrMethod, null);
    }

    public static object GetProperty(this object PobjItem, string PstrProperty, object[] PobjParams)
    {
        try
        {
            return PobjItem.GetType().InvokeMember(PstrProperty, BindingFlags.GetProperty, null, PobjItem, PobjParams, null);
        }
        catch
        {
            return null;
        }
    }

    public static object GetProperty(this object PobjItem, string PstrProperty)
    {
        return GetProperty(PobjItem, PstrProperty, null);
    }

    public static void SetProperty(this object PobjItem, string PstrProperty, object PobjValue)
    {
        try
        {
            object[] LobjVal = { PobjValue };
            PobjItem.GetType().InvokeMember(PstrProperty, BindingFlags.SetProperty, null, PobjItem, LobjVal, null);
        }
        catch
        {
            return;
        }
    }

To use this code, you would do something like this:

LobjCell.InvokeMethod("Calculate");
object LobjVal = LobjCell.GetProperty("Validation");
object LobjFormula = LobjVal.GetProperty("Formula1");

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