C# plug-ins continued — Interacting with one’s hosted application

By reeset / On / In C#, General Computing

Example Project Source: PluginProject.zip

Because I’ve been doing a lot of work with MarcEdit and plug-ins, I thought I’d post some sample code for anyone interested in how this might work.  Essentially, the sample project includes 3 parts — a host application, a set of Interfaces and a Shared library.  Making this work requires a couple of important parts. 

First, the host application (either the form or class), need to implement the set of interfaces.  So for example, if interaction with a form in the hosted application was need, you would configure the form to implement a set of interfaces.  This would look like:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace HostApp
{
public partial class Form1 : Form, HostInterfaces.IHost
{
//...
}

This implements the IHost class (link to msdn) — a generic class that allows you to

pass objects between dynamically loaded libraries.  .NET includes a IScript interface that allows for scripting functionality as well. 

Anyway, the interfaces are simply like delegates — they define the visible functions/methods that will be accessible to a foreign assembly.  This is the simpliest file to create.  It looks something like this:


using System;
using System.Collections.Generic;
using System.Text;

namespace HostInterfaces
{
public interface IHost
{
System.Windows.Forms.Label label { get;}
System.Windows.Forms.ToolStripButton AddButton(string caption);
void RemoveButton(System.Windows.Forms.ToolStripButton t);

}
}

Finally, the Dynamic assembly has the ability to work with any function/object within the host application that has been made public through the interface.  For this sample project, I’ve shown how to modify a label (on the host application), add a button to a toolbar and respond to click events from that button. 

The project is a simple one — but should go a long way towards showing how this works.

Cheers,

–TR

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