ZoomToLayerButton

ZoomToLayerButton.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using ESRI.ArcGIS.Framework;
using ESRI.ArcGIS.ArcMapUI;
using ESRI.ArcGIS.esriSystem;
using ESRI.ArcGIS.Carto;

namespace CustomUIElements
{
  public class ZoomToLayerButton : ESRI.ArcGIS.Desktop.AddIns.Button
  {
    public ZoomToLayerButton()
    {
    }

    protected override void OnClick()
    {
      ZoomToActiveLayerInTOC();
    }

    protected override void OnUpdate()
    {
      this.Enabled = ArcMap.Application != null;
    }

    #region "Zoom to Active Layer in TOC"
    public void ZoomToActiveLayerInTOC()
    {
      IMxDocument mxDocument = ArcMap.Application.Document as IMxDocument;
      IActiveView activeView = mxDocument.ActiveView;

      // Get the TOC
      IContentsView IContentsView = mxDocument.CurrentContentsView;

      // Get the selected layer
      System.Object selectedItem = IContentsView.SelectedItem;
      if (!(selectedItem is ILayer))
      {
        return;
      }
      ILayer layer = selectedItem as ILayer;
      // Zoom to the extent of the layer and refresh the map
      activeView.Extent = layer.AreaOfInterest;
      activeView.Refresh();
    }
    #endregion
  }
}

ZoomToLayerButton.vb

Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.Text
Imports System.IO
Imports ESRI.ArcGIS.Framework
Imports ESRI.ArcGIS.ArcMapUI
Imports ESRI.ArcGIS.esriSystem
Imports ESRI.ArcGIS.Geodatabase
Imports ESRI.ArcGIS.Carto

Namespace CustomUIElements
  Public Class ZoomToLayerButton
    Inherits ESRI.ArcGIS.Desktop.AddIns.Button

    Public Sub New()
    End Sub

    Protected Overrides Sub OnClick()
      ZoomToActiveLayerInTOC(TryCast(My.ArcMap.Application.Document, IMxDocument))
    End Sub

    Protected Overrides Sub OnUpdate()
      Enabled = My.ArcMap.Application IsNot Nothing
    End Sub

#Region "Zoom to Active Layer in TOC"


    Public Sub ZoomToActiveLayerInTOC(ByVal mxDocument As IMxDocument)
      If mxDocument Is Nothing Then
        Return
      End If
      Dim activeView As IActiveView = mxDocument.ActiveView

      ' Get the TOC
      Dim IContentsView As IContentsView = mxDocument.CurrentContentsView

      ' Get the selected layer
      Dim selectedItem As System.Object = IContentsView.SelectedItem
      If Not (TypeOf selectedItem Is ILayer) Then
        Return
      End If
      Dim layer As ILayer = TryCast(selectedItem, ILayer)
      ' Zoom to the extent of the layer and refresh the map
      activeView.Extent = layer.AreaOfInterest
      activeView.Refresh()
    End Sub
#End Region
  End Class


End Namespace