Diving into C#

Outside, it's been a chilly few days here in Denver, which has given me the opportunity to ramp up some of my skills. I'm a VB guy, but recently I dove into building some ArcObjects components in C#. The experience reminded me of a long-ago, early-morning, Adirondack scout camp, "polar bear" swim. Standing before the icy black, I shivered at the thought of jumping in... but the experience was surprisingly painless, and it was over and done before I knew it.

I started by working through the ESRI C# Walkthrough: Creating a simple command for ArcMap

Since I'm using Visual Studio 2005 (.NET 2.0) and I'm also using the Visual C# Express Edition, I found a few differences from the ESRI documented steps. I figured I'd note those differences here:

Create a new class library

Steps worked fine

Reference the ESRI object libraries

I found it useful to also reference to ESRI.ArcGIS.Utility. I used this later for component category registration.

Create a zoom-in command

Steps worked fine

Add a using directive

To define my class, I modified the default .cls. By default, you'll get these directives:

using System;

using System.Collections.Generic;

using System.Text;

I found that I only need the first, and I also added this directive:

using ESRI.ArcGIS.Utility.CATIDs;

Implement the ICommand interface

ESRI Step 4 states "Right-click the ICommand interface, click Add, and then click Implement Interface"...I couldn't find this functionality. Perhaps its because I'm using the Express version...
So, I manually stubbed out my class...actually, I copy/pasted from another ESRI dev sample.

Adding code to the members of ICommand

IntPntr is defined in System, so you'll either need a directive (see above), or you'll have to fully qualify:

private System.IntPtr m_hBitmap;

Returning the ICommand::Bitmap property

Steps worked fine

Expose the ZoomIn class to COM

To reg. for COM interop, Goto Project > Properties > Build > Register for COM interop. Also, maybe this is obvious, but I had to add GuidGen.exe as an External Tool (again, I'm using the Express Version of Visual Studio). Location for me was: "C:\Program Files\Microsoft Visual Studio 8\Common7\Tools"

Adding COM category registration functions

I did this differently. Since we're using ESRI.ArcGIS.Utility.CATIDs, you can do this instead:

#region "Component Category Registration"

[ComRegisterFunction()]

static void Reg(string regKey)

{

MxCommands.Register(regKey);

}

[ComUnregisterFunction()]

static void Unreg(string regKey)

{

MxCommands.Unregister(regKey);

}

#endregion

Compiling the project, Use the command in ArcMap

In order to get a .tlb, I had to go to Project > Properties > Application > Assembly Info > and check 'Make Assembly COM-visible'

Stepping through the command with the debugger

I found that I wasn't able to do this with the Express Version of VS... but I was hungry for lunch and I didn't try to hard...

Talk to you soon,

-Cory

www.eicher-gis.com