Create a command by inheriting from BaseCommand

Click here to get the sample associated with this walkthrough.

In this topic

• About creating a command by inheriting from BaseCommand
• Create a class library
• Add references
• Delete the class1 file
• Create a ZoomToLayer command
• Change the default icon bitmap
• Inherit the BaseCommand abstract class
• Add code to the overridden constructor of BaseCommand
• Add ZoomToLayer functionality
• Expose the ZoomToLayer class to COM
• Compile the project
• Use the command in ArcMap
• Debug the command
• Deploy the command

About creating a command by inheriting from BaseCommand

Create a class library

1. Start Visual Studio.
   

Add references

1. As part of the ArcGIS Visual Studio Integration Framework features, the ArcGIS Project Wizard guides you through adding in references to .NET assemblies. The ArcGIS Project Wizard appears after you click OK from the previously shown New Project dialog box. Although there are other formats for viewing the available Esri references, use the default Filter by: Product Features view. See the following screen shot:
   
   
   

2. Since you are creating an ArcGIS for Desktop application, only assemblies relevant for ArcGIS for Desktop display. Click the Desktop ArcMap node and select the following assemblies: ESRI.ArcGIS.ADF.Local, ESRI.ArcGIS.ArcMapUI, ESRI.ArcGIS.Carto, ESRI.ArcGIS.Framework, ESRI.ArcGIS.Geometry, ESRI.ArcGIS.System, and ESRI.ArcGIS.SystemUI. To select multiple items at one time, press and hold the Ctrl key, then click each item. Click Add to have your references appear in the Selected Assemblies pane. See the following screen shot:
   
   

3. Click Finish to create your project.
4. You still need a reference to System.Drawing; therefore, click the Project menu, click Add Reference, click the .NET tab, then click the System.Drawing assembly under the Component Name area. See the following screen shot:
   
   

5. Click OK to close the Add Reference dialog box and add the assembly reference.
   

Delete the class1 file

Create a ZoomToLayer command

1. In the Solution Explorer, right-click the project, click Add, and click New Item.
2. In the Add New Item dialog box, click to expand the project items, then click ArcGIS under the Categories pane. Click Base Command under the Templates pane. Name the class ZoomToLayer.cs (C#) or ZoomToLayer.vb (VB .NET) and click Add. See the following screen shot:
   
   
   
3. When the ArcGIS New Item Wizard Options dialog box appears, click Desktop or ArcMap Command, then click OK. See the following screen shot:
   
   

Change the default icon bitmap

1. In the Solution Explorer, right-click ZoomToLayer.bmp, click Delete, then click OK to permanently delete the ZoomToLayer.bmp file.
2. In the Solution Explorer, right-click the CommandInheritingBaseCommand project, click Add, and click Existing Item.
3. On the Add Existing Item dialog box, click the Files of type drop-down arrow and select Image Files.
4. Browse for an image file and click Add to copy it to your project directory. See the following screen shot:
   
   
     
5. Right-click the image file in the Solution Explorer and click Properties. In the Properties window, click the Build Action drop-down arrow and select Embedded Resource. Name the bitmap file ZoomToLayer.png. See the following screen shot:
   
   
   
   The bitmap icon file is ready to use later in this walkthrough.

Inherit the BaseCommand abstract class

public sealed class ZoomToLayer: BaseCommand

Public NotInheritable Class ZoomToLayer
Inherits BaseCommand

[ProgId("CommandInheritingBaseCommand.ZoomToLayer")]

<ComClass(ZoomToLayer.ClassId, ZoomToLayer.InterfaceId, ZoomToLayer.EventsId), _
          ProgId("CommandInheritingBaseCommand.ZoomToLayer")>

Add code to the overridden constructor of BaseCommand

1. Scroll in the code window to find the constructor for the ZoomToLayer class in the ZoomToLayer file. All the properties are empty strings and update their values for the command as shown in the following code example:
   

public ZoomToLayer()
{
    //
    // TODO: Define values for the public properties.
    //
    base.m_category="Developer Samples"; //Localizable text.
    base.m_caption="Zoom To Layer"; //Localizable text.
    base.m_message="Zoom to the extent of the active layer in the TOC"; 
        //Localizable text. 
    base.m_toolTip="Zoom To Layer"; //Localizable text. 
    base.m_name="DeveloperSamples_ZoomToLayer"; 
        //Unique ID, not localizable (for example,  "MyCategory_ArcMapCommand").
    try
    {
        //
        // TODO: If necessary, change the bitmap name.
        //
        string bitmapResourceName=GetType().Name + ".png";
        base.m_bitmap=new Bitmap(GetType(), bitmapResourceName);
    }
    catch (Exception ex)
    {
        System.Diagnostics.Trace.WriteLine(ex.Message, "Invalid Bitmap");
    }
}

' A creatable COM class must have a Public Sub New()
' with no parameters; otherwise, the class will not be
' registered in the COM registry and cannot be created
' via CreateObject.

Public Sub New()
    MyBase.New()
    ' TODO: Define values for the public properties.
    MyBase.m_category="Developer Samples" 'Localizable text.
    MyBase.m_caption="Zoom To Layer" 'Localizable text.
    MyBase.m_message="Zoom to the extent of the active layer in the TOC" 'Localizable text.
    MyBase.m_toolTip="Zoom To Layer" 'Localizable text.
    MyBase.m_name="DeveloperSamples_ZoomToLayer 'Unique ID, not localizable (for example, "MyCategory_ArcMapCommand").
    Try
    'TODO: If necessary, change the bitmap name.
    Dim bitmapResourceName As String=Me.GetType().Name + ".png"
    MyBase.m_bitmap=New Bitmap(Me.GetType(), bitmapResourceName)
    Catch ex As Exception
    System.Diagnostics.Trace.WriteLine(ex.Message, "Invalid Bitmap")
    End Try
    
End Sub

Add ZoomToLayer functionality

#region "Zoom to Active Layer in TOC"

/// <summary>Zooms to the selected layer in the table of contents (TOC) associated with the active view.</summary>
/// <param name="mxDocument">An IMxDocument interface.</param>
/// <remarks></remarks>
public void ZoomToLayerInTOC(IMxDocument mxDocument)
{
    if (mxDocument == null)
    {
        return ;
    }
    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

#Region "Zoom to Active Layer in TOC"

''' <summary>Zooms to the selected layer in the TOC associated with the active view.</summary>
''' <param name="mxDocument">An IMxDocument interface.</param>
''' <remarks></remarks>

Public Sub ZoomToLayerInTOC(ByVal mxDocument As IMxDocument)
    
    If mxDocument Is Nothing Then
        Return
    End If
    
    ' Get the map.
    Dim activeView As IActiveView=mxDocument.ActiveView
    
    ' Get the TOC.
    Dim contentsView As IContentsView=mxDocument.CurrentContentsView
    
    ' Get the selected layer.
    Dim selectedItem As System.Object=contentsView.SelectedItem
    If Not (TypeOf selectedItem Is ILayer) Then
        Return
    End If
    
    Dim layer As ILayer=TryCast(selectedItem, ILayer) ' Dynamic cast.
    
    ' Zoom to the extent of the layer and refresh the map.
    activeView.Extent=layer.AreaOfInterest
    activeView.Refresh()
    
End Sub

#End Region

2. To take advantage of the functionality for the Zoom to Active Layer in TOC ArcGIS snippet, call the function and supply the appropriate input parameter. The required parameter is an ESRI.ArcGIS.ArcMapUI.IMxDocument interface, and you can use another ArcGIS snippet to get the MxDocument to pass in. 
3. To access ArcGIS snippets, right-click the Visual Studio code editor window at the necessary insertion point (before the end of the class file), and Insert Snippet: Double-click `ArcObjects` from the popup window. Double-click 'Mapping'. Double click the 'Page Layout' and then Double-click  'Get PageLayout from ArcMap'.
   

#region "Get MxDocument from ArcMap"

/// <summary>Get MxDocument from ArcMap.</summary>
/// <param name="application">An IApplication interface that is the ArcMap application.</param>
/// <returns>An IMxDocument interface.</returns>
/// <remarks></remarks>
public IMxDocument GetMxDocument(IApplication application)
{

    if (application == null)
    {
        return null;
    }

    IMxDocument document=application.Document;
    IMxDocument mxDocument=(IMxDocument)(document); // Explicit cast.

    return mxDocument;

}

#endregion

#Region "Get MxDocument from ArcMap"

''' <summary>Get MxDocument from ArcMap.</summary>
''' <param name="application">An IApplication interface that is the ArcMap application.</param>
''' <returns>An IMxDocument interface.</returns>
''' <remarks></remarks>

Public Function GetMxDocument(ByVal application As IApplication) As IMxDocument
    
    If application Is Nothing Then
        Return Nothing
    End If
    
    Dim document As IDocument=application.Document
    Dim mxDocument As IMxDocument=CType(document, IMxDocument) ' Explicit cast.
    
    Return mxDocument
    
End Function

#End Region

3. Now that the snippets are in place, call them from the OnClick method to execute the code when the custom command is clicked in ArcMap. To call the GetMxDocument method, pass in an ESRI.ArcGIS.Framework.IApplication interface (previously specified) as member variable m_application. To call the ZoomToLayerInTOC method, pass in an ESRI.ArcGIS.ArcMapUI.IMxDocument interface that is the return value from the GetMxDocument method. Call both snippets in order as shown in the following code example:
   

/// <summary>
/// Occurs when this command is clicked.
/// </summary>
public override void OnClick()
{
    IMxDocument mxDocument=GetMxDocument(m_application);

    ZoomToLayerInTOC(mxDocument);
}

Public Overrides Sub OnClick()
Dim mxDocument As IMxDocument=GetMxDocument(m_application)
ZoomToLayerInTOC(mxDocument)
End Sub

Expose the ZoomToLayer class to COM

Compile the project

1. Make sure you save your project and the work you have done.
2. Click the Build menu and click Build Solution.

Use the command in ArcMap

1. Start ArcMap and open a map document that has data layers.
2. Click the Tools menu and click Customize to open the Customize dialog box. Click the Commands tab, then click Developer Samples under the Categories pane.
   • If you do not see your Category or Command, verify Register for COM Interop is checked in your Visual Studio Project Properties under the Build tab and rebuild your project. See the following screen shot:
     
     
3. On the Commands pane, click the Zoom To Layer CSharp command, and drag it onto an ArcMap toolbar, then click Close on the Customize dialog box. See the following screen shot:
   
   
   
4. Click any layer in the TOC and click the ZoomToLayer button. The map zooms to the extent of that layer. See the following screen shot:
   
   

Debug the command

1. Return to the solution in the Visual Studio IDE. 
2. Verify that ArcMap.exe is set as the external program to use for debugging. This is another feature set for you by the ArcGIS project template when you create your project.
   1. Right-click the CommandInheritingBaseCommand project in the Solution Explorer window and click Properties.
   2. Click the Debug tab on the property page.
   3. Under Start Action, set Start external program to use ArcMap.exe in the Bin folder of your ArcGIS install directory. See the following screen shot: 
      
      

Deploy the command

See Also: