Addin Button Icon

[ravindrathorat]

Hi Team

@YuhanZhang 

I am trying to crate addin in C#. I have created sample addin. It works too. But I am trying to add icon for button. It not happening. Could you please provide code snippet to add button icon.

[JhoelForshav]

Hi @ravindrathorat 
You need to convert your Icon to IPictureDisp in the two sizes 32x32 and 16x16. I don't know how you've set it up but I'm guessing you have an ico-file in your resources with these two sizes, or two different files maybe.

I don't typically write in C# but I made an attempt to give you an example here with a converter and how to set a button up:

using System.Drawing;
using System.Runtime.InteropServices;
using stdole;

// Step 1: The PictureDispConverter - converts .NET icons to COM IPictureDisp
// Inventor's API is COM-based so it needs IPictureDisp, not System.Drawing.Icon
public sealed class PictureDispConverter
{
    // P/Invoke to OleAut32.dll - this is the Win32 COM function that creates IPictureDisp
    [DllImport("OleAut32.dll", EntryPoint = "OleCreatePictureIndirect", 
               ExactSpelling = true, PreserveSig = false)]
    private static extern IPictureDisp OleCreatePictureIndirect(
        [MarshalAs(UnmanagedType.AsAny)] object picdesc,
        ref Guid iid,
        [MarshalAs(UnmanagedType.Bool)] bool fOwn);

    private static Guid iPictureDispGuid = typeof(IPictureDisp).GUID;

    // PICTDESC structs describe the picture to COM
    private static class PICTDESC
    {
        public const short PICTYPE_ICON = 3;

        [StructLayout(LayoutKind.Sequential)]
        public class Icon
        {
            internal int cbSizeOfStruct = Marshal.SizeOf(typeof(Icon));
            internal int picType = PICTYPE_ICON;
            internal IntPtr hicon = IntPtr.Zero;
            internal int unused1;
            internal int unused2;

            public Icon(System.Drawing.Icon icon)
            {
                // Convert the .NET icon to a Win32 HICON handle
                this.hicon = icon.ToBitmap().GetHicon();
            }
        }
    }

    public static IPictureDisp ToIPictureDisp(System.Drawing.Icon icon)
    {
        var pictIcon = new PICTDESC.Icon(icon);
        return OleCreatePictureIndirect(pictIcon, ref iPictureDispGuid, true);
    }
}

// Step 2: In your Activate method - load the icon and create the button
public void Activate(Inventor.ApplicationAddInSite addInSiteObject, bool firstTime)
{
    var app = addInSiteObject.Application;

    // Load icon at two sizes - Inventor expects both large (32x32) and small (16x16)
    var largeIcon = new Icon(Properties.Resources.AppIcon, 32, 32);
    var smallIcon = new Icon(Properties.Resources.AppIcon, 16, 16);

    // Convert to COM IPictureDisp that Inventor understands
    IPictureDisp largePicture = PictureDispConverter.ToIPictureDisp(largeIcon);
    IPictureDisp smallPicture = PictureDispConverter.ToIPictureDisp(smallIcon);

    // Create the button definition with both icons
    var controlDefs = app.CommandManager.ControlDefinitions;
    var button = controlDefs.AddButtonDefinition(
        "My Button",                          // Display name
        "cmd_my_button",                      // Internal ID - must be unique
        CommandTypesEnum.kShapeEditCmdType,   // Command type
        "{your-addin-client-id}",             // Your addin's GUID
        "Tooltip text",                       // Short tooltip
        "Longer description tooltip",         // Long tooltip
        smallPicture,                         // 16x16 icon
        largePicture,                         // 32x32 icon
        ButtonDisplayEnum.kDisplayTextInLearningMode
    );

    if (firstTime)
        AddToUserInterface(button);
}

 If you don't get it to work - feel free to share more information about your project structure etc. Maybe even share your entire solution. Then I'm sure we'll figure it out

[TylerWarner33]

@ravindrathorat 

You can review the sample provided with the SDK that shows how to do this, update 2026 to the version you are using:

%PUBLIC%\Documents\Autodesk\Inventor 2026\SDK\DeveloperTools\Samples\VCSharp.NET\AddIns\SimpleAddIn

 
If you don't have the 'Developer Tools' installed, you would run the 'developertools.msi' file, again, update 2026 to the version you are using:

%PUBLIC%\Documents\Autodesk\Inventor 2026\SDK

A common error that prevents the image from loading is forgetting to include the 'StandardIcon' or 'LargeIcon' parameter when defining the ControlDefinition.