Plugin to Host - return Control

Question

I'm working on an application that supports various plugins (well, that's planned at least). And I'd love to have it beautiful.

So I want to let the plugin developer send a big control (like a panel or other containers) to my host application and have the user setup their settings for the plugin in the application.

That would take the plugin-developer's effort to somehow implement a settings-panel that runs by in an own window.

Thing is, I'm not sure how to do that. I can pass variables to my host application but as soon as I try to add the control to my container panel, I get a RemoteException, telling me that the field 'parent' on type 'System.Windows.Forms.Control' can't be found.

I tried to add the plugin-control that way:

panel.Controls.Add(pluginControl);

If I try it the other way around:

pluginControl.Parent = panel;

I get a SerializationException because the class System.Windows.Forms.Control isn't marked Serializable.

Maybe some person ran into the same thing and can help me. Let me know if you need more information!

Edit: Have a look on my current implementation: https://dl.dropboxusercontent.com/u/62845853/Random%20crap/NotModified_SamplePluginSystem.zip

Answer 1

I tried something which you can adorn to your needs:

First i created a PluginBase class and the proper EventArgs in a ClassLibrary:

 public abstract class PluginBase
{
    public abstract void Initialize();

    protected void showControl(UserControl control)
    {
        ShowControl(this, new ControlToBeShownEventArgs() { TheControl = control });
    }

    public event EventHandler<ControlToBeShownEventArgs> ShowControl = delegate { };
}

public class ControlToBeShownEventArgs : EventArgs
{
    public UserControl TheControl { get; set; }
}

This library is referenced by every Plugin and by the host application. The Plugin is in turn also a Class Library (build path set to the one of the host) inside i made a plugin inheriting this base type:

class SomePlugin : PluginBase
{
    public override void Initialize()
    {
        showControl(new UserControl1());
    }
}

The UserControl1 is the Control to be shown.

Done that, I next added the following code to the main window of the host:

    List<PluginBase> plugins = new List<PluginBase>();

    private void Form1_Load(object sender, EventArgs e) //Hook in the event too
    {
        DirectoryInfo dir = (new FileInfo(Assembly.GetExecutingAssembly().Location)).Directory;
        foreach (var item in dir.GetFiles())
        {
            if (item.Name.Contains("Plugin") && item.Name.EndsWith(".dll"))
            {
                Assembly ass = Assembly.LoadFile(item.FullName);
                foreach (Type type in ass.GetTypes().Where(t => t.BaseType.Name == "PluginBase"))
                {
                    PluginBase pibase = (PluginBase)Activator.CreateInstance(type,false);
                    plugins.Add(pibase);
                }

            }
        }
        foreach (var item in plugins)
        {
            item.ShowControl += item_ShowControl;
            item.Initialize();
        }

    }

    void item_ShowControl(object sender, ControlToBeShownEventArgs e)
    {
        this.Controls.Add(e.TheControl);
    }