How to include image in metadata for plug-in DLL using MEF?

Question

How to include image in metadata for plug-in DLL using MEF?

C # .NET 4.0 WinForms

I started to implement the MEF sample code from this tutorial , which describes how to create a custom ExportAttribute attribute for metadata. Everything was done smoothly until I tried to include the image from the resource file in the metadata. The goal is to extract the name, description and icon for each plug-in DLL as metadata for creating a plug-in menu in the main program.

Now I get a compilation error:

"The attribute argument must be a constant expression, typeof expression, or an array creation expression of type attribute parameter"

So now I have a problem and you need to find out:

1) How to include an image in an attribute?

or

2) How to include metadata in MEF without using attributes?

Here is the code I'm using:

In the contract class:

// Metadata contract interface
public interface IPlugInMetadata
{
    string PlugInTitle { get; }
    string PlugInDescription { get; }
    Image PlugInIcon { get; }
}

// Plug-In contract interface
public interface IPlugIn
{
    void StartPlugIn(object systemObject);
    void StopPlugin();
}

Custom Attribute in DLL Plug-In:

[MetadataAttribute]
[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class PluginMetadataAttribute : ExportAttribute
{
    public string title { get; set; }
    public string description { get; set; }
    public Image icon { get; set; }

    public PluginMetadataAttribute(string plugInTitle, string plugInDescription, Image plugInIcon) 
        : base(typeof(IPlugInMetadata))
    {
        title = plugInTitle;
        description = plugInDescription;
        icon = plugInIcon;
    }
}

And finally, the program class in the DLL Plug-In:

[Export(typeof(IPlugIn))]
[PluginMetadata(ResourceFile.PlugInTitle, ResourceFile.PlugInDescription, ResourceFile.PlugInIcon24)]
public class Program : IPlugIn
{
    public void StartPlugIn(object systemObject)
    {
        Console.WriteLine("Start Plug-In: " + ResourceFile.PlugInTitle);
    }

    public void StopPlugin()
    {
        Console.WriteLine("Stop Plug-In: " + ResourceFile.PlugInTitle);
    }
}

This line creates an error.

[PluginMetadata(ResourceFile.PlugInTitle, ResourceFile.PlugInDescription, ResourceFile.PlugInIcon24)]

Obviously, the ResourceFile is not considered a constant, but then how can I use the image as metadata, or is this impossible? (note that the image is set to "Embedded in.resx")

Thanks for any help or suggestions!

+5

c # plugins image metadata mef

user1689175 Jan 31 '13 at 19:58

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1 answer

user1689175 · Accepted Answer · 2013-02-01T23:51:19+0000

Found a solution:

, , MEF. DLL , EXE . , .NET:

Icon MyDLLIcon = Icon.ExtractAssociatedIcon(DLLFilePath);

, MEF, .

, Plug-In , , , - .

:

, 5 (MainProgram, ContractInterfaces, PlugInA, PlugInB, PlugInC)
Post Build DLL "Plug-Ins"
MainProgram (WinForm) DLL- ListView .
ListView Plug-In ( Lazy-) .
, TextBox , , .
Title, Description Version Plug-In

DLL ( Visual Studio 6 Common Graphics Misc)

DLL, ListView, DLL ( Plug-In ListView).

# WinForm "MainProgram" ( VS 2010):

- Code Sample Using, :

;
System.Collections.Generic;
System.ComponentModel.Composition;
System.ComponentModel.Composition.Hosting;
System.Drawing;
System.IO;
System.Windows.Forms;
ContractInterfaces;
( ) MainProgram

public partial class Form1 : Form
{
    // Prerequisites to run:
    //      1)  Project, Add Reference, Projects, ContractInterface
    //      2)  Project, Add Reference, .NET, System.ComponentModel.Composition

    [ImportMany(typeof(IPlugIn))]
    private IEnumerable<Lazy<IPlugIn, IPlugInMetadata>> LoadedPlugIns;

    List<PlugInInfo> AvailablePlugIns = null;


    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        // Get a list of the available Plug-Ins
        AvailablePlugIns = GetPlugInList();

        // Prepare an ImageList to hold the DLL icons
        ImageList ImgList = new ImageList();
        ImgList.ColorDepth = ColorDepth.Depth32Bit;
        ImgList.ImageSize = new Size(32, 32);

        // Populate ImageList with Plug-In Icons
        foreach (var item in AvailablePlugIns)
        {
            ImgList.Images.Add(item.PlugInIcon.ToBitmap());
        }

        // Assign the ImageList to the ListView
        listView1.LargeImageList = ImgList;

        int imageIndex = 0;

        // Create the ListView items
        foreach (var item in AvailablePlugIns)
        {
            listView1.Items.Add(item.PlugInTitle, imageIndex);
            imageIndex++;
        }

        listView1.MouseDoubleClick += new MouseEventHandler(listView1_MouseDoubleClick);
    }

    void listView1_MouseDoubleClick(object sender, MouseEventArgs e)
    {
        // Get the Plug-In index number 
        int plugInNum = listView1.SelectedItems[0].Index;

        PlugInInfo selectedPlugIn = AvailablePlugIns[plugInNum];

        // Call the StartPlugIn method in the selected Plug-In.
        // Lazy Instantiation will fully load the Assembly here
        selectedPlugIn.PlugIn.StartPlugIn(this);

        Console.WriteLine("Plug-In Title:          {0}", selectedPlugIn.PlugInTitle);
        Console.WriteLine("Plug-In Description:    {0}", selectedPlugIn.PlugInDescription);
        Console.WriteLine("Plug-In Version:        {0}", selectedPlugIn.PlugInVersion);
        Console.WriteLine();
    }



    private List<PlugInInfo> GetPlugInList()
    {
        // Create a List to hold the info for each plug-in
        List<PlugInInfo> plugInList = new List<PlugInInfo>();

        // Set Plug-In folder path to same directory level as Solution
        string plugInFolderPath = System.IO.Path.Combine(Application.StartupPath, @"..\..\..\Plug-Ins");

        // Test if the Plug-In folder exists
        if (!Directory.Exists(plugInFolderPath))
        {
            // Plug-In Folder is missing, so try to create it
            try
            { Directory.CreateDirectory(plugInFolderPath); }
            catch
            { MessageBox.Show("Failed to create Plug-In folder", "Folder Creation Error:", MessageBoxButtons.OK, MessageBoxIcon.Exclamation); }
        }

        try
        {
            // Create a catalog of plug-ins
            var catalog = new DirectoryCatalog(plugInFolderPath, "*.dll");
            AggregateCatalog plugInCatalog = new AggregateCatalog();
            plugInCatalog.Catalogs.Add(catalog);
            CompositionContainer container = new CompositionContainer(plugInCatalog);

            // This line will fetch the metadata from each plug-in and populate LoadedPlugIns
            container.ComposeParts(this);

            // Save each Plug-Ins metadata
            foreach (var plugin in LoadedPlugIns)
            {
                PlugInInfo info = new PlugInInfo();

                info.PlugInTitle = plugin.Metadata.PlugInTitle;
                info.PlugInDescription = plugin.Metadata.PlugInDescription;
                info.PlugInVersion = plugin.Metadata.PlugInVersion;
                info.PlugIn = plugin.Value;

                plugInList.Add(info);
            }

            int index = 0;

            // Extract icons from each Plug-In DLL and store in Plug-In list
            foreach (var filePath in catalog.LoadedFiles)
            {
                plugInList[index].PlugInIcon = Icon.ExtractAssociatedIcon(filePath);
                index++;
            }
        }
        catch (FileNotFoundException fex)
        {
            Console.WriteLine("File not found exception : " + fex.Message);
        }
        catch (CompositionException cex)
        {
            Console.WriteLine("Composition exception : " + cex.Message);
        }
        catch (DirectoryNotFoundException dex)
        {
            Console.WriteLine("Directory not found exception : " + dex.Message);
        }

        return plugInList;
    }
}


public class PlugInInfo
{
    public string PlugInTitle { get; set; }
    public string PlugInDescription { get; set; }
    public string PlugInVersion { get; set; }
    public Icon PlugInIcon { get; set; }
    public IPlugIn PlugIn { get; set; }
}

ListView "listView1" . TextBoxes .

"ContractInterfaces", :

System.Windows.Forms;
( ) ContractInterfaces

// Prerequisites to run:
//      1)  Project, Add Reference, .NET, "System.Windows.Forms"

public interface IPlugIn
{
    void StartPlugIn(Form mainForm);
}

public interface IPlugInMetadata
{
    string PlugInTitle { get; }
    string PlugInDescription { get; }
    string PlugInVersion { get; }
}

"PlugInA", :

;
System.ComponentModel.Composition;
System.Windows.Forms;
ContractInterfaces;
( ) PlugInA

    // Prerequisites to run:
//      1)  Project, Add Reference, Projects, "ContractInterface"
//      2)  Project, Add Reference, .NET, "System.Windows.Forms"
//      3)  Project, Add Reference, .NET, "System.ComponentModel.Composition"
//      4)  Project, Properties, Build Events, Post-Build event command line:
//          xcopy "$(ProjectDir)$(OutDir)$(TargetFileName)"  "$(SolutionDir)Plug-Ins\" /Y
//      5)  Project, Properties, Build Events, Run the post-build event:, Always
//      6)  Project, Properties, Application, Icon and manifest, [Select an icon]

[Export(typeof(IPlugIn))]
[PluginMetadata]
public class Program : IPlugIn
{
    private Form MainForm;

    public void StartPlugIn(Form mainForm)
    {
        MainForm = mainForm;

        // Place a TextBox on the Main Form
        TextBox textBox = new TextBox();
        textBox.Text = "PlugInA";
        MainForm.Controls.Add(textBox);
        textBox.Width = 65;
        textBox.Height = 20;
        textBox.Top = 0;
        textBox.Left = 0;
    }
}

// Create a custom strong-typed Metadata Attribute for MEF
[MetadataAttribute]
[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class PluginMetadataAttribute : ExportAttribute
{
    public string PlugInTitle { get; set; }
    public string PlugInDescription { get; set; }
    public object PlugInVersion { get; set; }

    public PluginMetadataAttribute()
        : base(typeof(IPlugInMetadata))
    {
        PlugInTitle = "Plug-In A";
        PlugInDescription = "This is Plug-In A";
        PlugInVersion = "1.0.0.0";
    }
}

"PlugInB", :

;
System.ComponentModel.Composition;
System.Windows.Forms;
ContractInterfaces;
( ) PlugInB

// Prerequisites to run:
//      1)  Project, Add Reference, Projects, "ContractInterface"
//      2)  Project, Add Reference, .NET, "System.Windows.Forms"
//      3)  Project, Add Reference, .NET, "System.ComponentModel.Composition"
//      4)  Project, Properties, Build Events, Post-Build event command line:
//          xcopy "$(ProjectDir)$(OutDir)$(TargetFileName)"  "$(SolutionDir)Plug-Ins\" /Y
//      5)  Project, Properties, Build Events, Run the post-build event:, Always
//      6)  Project, Properties, Application, Icon and manifest, [Select an icon]

[Export(typeof(IPlugIn))]
[PluginMetadata]
public class Program : IPlugIn
{
    private Form MainForm;

    public void StartPlugIn(Form mainForm)
    {
        MainForm = mainForm;

        // Place a TextBox on the Main Form
        TextBox textBox = new TextBox();
        textBox.Text = "PlugInB";
        MainForm.Controls.Add(textBox);
        textBox.Width = 65;
        textBox.Height = 20;
        textBox.Top = 30;
        textBox.Left = 0;
    }
}

// Create a custom strong-typed Metadata Attribute for MEF
[MetadataAttribute]
[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class PluginMetadataAttribute : ExportAttribute
{
    public string PlugInTitle { get; set; }
    public string PlugInDescription { get; set; }
    public object PlugInVersion { get; set; }

    public PluginMetadataAttribute()
        : base(typeof(IPlugInMetadata))
    {
        PlugInTitle = "Plug-In B";
        PlugInDescription = "This is Plug-In B";
        PlugInVersion = "1.0.0.1";
    }
}

"PlugInC", :

;
System.ComponentModel.Composition;
System.Windows.Forms;
ContractInterfaces;
( ) PlugInC

// Prerequisites to run:
//      1)  Project, Add Reference, Projects, "ContractInterface"
//      2)  Project, Add Reference, .NET, "System.Windows.Forms"
//      3)  Project, Add Reference, .NET, "System.ComponentModel.Composition"
//      4)  Project, Properties, Build Events, Post-Build event command line:
//          xcopy "$(ProjectDir)$(OutDir)$(TargetFileName)"  "$(SolutionDir)Plug-Ins\" /Y
//      5)  Project, Properties, Build Events, Run the post-build event:, Always
//      6)  Project, Properties, Application, Icon and manifest, [Select an icon]

[Export(typeof(IPlugIn))]
[PluginMetadata]
public class Program : IPlugIn
{
    private Form MainForm;

    public void StartPlugIn(Form mainForm)
    {
        MainForm = mainForm;

        // Place a TextBox on the Main Form
        TextBox textBox = new TextBox();
        textBox.Text = "PlugInC";
        MainForm.Controls.Add(textBox);
        textBox.Width = 65;
        textBox.Height = 20;
        textBox.Top = 60;
        textBox.Left = 0;
    }
}

// Create a custom strong-typed Metadata Attribute for MEF
[MetadataAttribute]
[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class PluginMetadataAttribute : ExportAttribute
{
    public string PlugInTitle { get; set; }
    public string PlugInDescription { get; set; }
    public object PlugInVersion { get; set; }

    public PluginMetadataAttribute()
        : base(typeof(IPlugInMetadata))
    {
        PlugInTitle = "Plug-In C";
        PlugInDescription = "This is Plug-In C";
        PlugInVersion = "1.0.0.2";
    }
}

:

Solution "Project Dependencies...". :

MainProgram - - ContractInterface
PlugInA - - ContractInterface
PlugInB - - ContractInterface
PlugInC - - ContractInterface
ContractInterface - - []

Solution "Project Build Order...". :

ContractInterface
PlugInB
PlugInC
MainProgram

. 3 DLL, "Plug-Ins" , (*.sln). , , Plug-In. , ListView . ListView, .

, , -...

How to include image in metadata for plug-in DLL using MEF?

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