IExternal Command Availability Interface

An interface that should be implemented to provide the implementation for a accessibility check for a Revit add-in External Command.

Namespace: Autodesk.Revit.UI
Assembly: RevitAPIUI (in RevitAPIUI.dll) Version: 25.0.0.0 (25.0.0.0)

Syntax

C++

public interface IExternalCommandAvailability

Public Interface IExternalCommandAvailability

public interface class IExternalCommandAvailability

type IExternalCommandAvailability = interface end

The IExternalCommandAvailability type exposes the following members.

Methods

	Name	Description
	IsCommandAvailable	Implement this method to provide control over whether your external command is enabled or disabled.

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Remarks

This interface should share the same assembly with add-in External Command.

Example

C++

public class SampleAccessibilityCheck : IExternalCommandAvailability
{
    public bool IsCommandAvailable(Autodesk.Revit.UI.UIApplication applicationData, 
        CategorySet selectedCategories)
    {
        // Allow button click if there is no active selection
        if (selectedCategories.IsEmpty)
            return true;
        // Allow button click if there is at least one wall selected
        foreach (Category c in selectedCategories)
        {
            if (c.BuiltInCategory == BuiltInCategory.OST_Walls)
                return true;
        }
        return false;
    }
}

Public Class SampleAccessibilityCheck
    Implements IExternalCommandAvailability
    Public Function IsCommandAvailable(applicationData As Autodesk.Revit.UI.UIApplication, selectedCategories As CategorySet) As Boolean Implements IExternalCommandAvailability.IsCommandAvailable
        ' Allow button click if there is no active selection
        If selectedCategories.IsEmpty Then
            Return True
        End If
        ' Allow button click if there is at least one wall selected
        For Each c As Category In selectedCategories
            If c.BuiltInCategory = BuiltInCategory.OST_Walls Then
                Return True
            End If
        Next
        Return False
    End Function
End Class

Reference

Autodesk.Revit.UI Namespace

IExternalCommandAvailability Interface

IExternal Command Availability Interface

Reference