ArcObjects on Marko Apfel

LINQ and ArcObjects

Wed, 12 Sep 2012 15:20:00 +0200

Motivation

LINQ (language integrated query) is a component of the Microsoft. NET Framework since version 3.5. It allows a SQL-like query to various data sources such as SQL, XML etc.

Like SQL also LINQ to SQL provides a declarative notation of problem solving – i.e. you don’t need describe in detail how a task could be solved, you describe what to be solved at all. This frees the developer from error-prone iterator constructs.

Interop effects by resolving and instantiating types with ArcObjects

Fri, 25 Nov 2011 14:10:00 +0100

Problem

this code does not work

Type t = typeof(ESRI.ArcGIS.Framework.AppRefClass);
System.Object obj = Activator.CreateInstance(t);

but yet this code

Type t = Type.GetTypeFromCLSID(typeof(ESRI.ArcGIS.Framework.AppRefClass).GUID);
System.Object obj = Activator.CreateInstance(t);

Reason

In the first variant the runtime tries to cast to AppRefClass. This is not possible.

And in the second one, the runtime does not knows anything about AppRefClass. So it leave it as IUnknown.

"Failure has occurred while loading a type."

Fri, 28 Oct 2011 12:08:00 +0200

Motivation

During programming suddenly this error (Failure has occurred while loading a type) was thrown by accessing a artifact of a referenced library.

In such cases I take the assembly fusion logger fuslogvw to search for problems of loading assemblies. Sometimes an old version from a not expected folder is binded. But all bindings were correct.

Suppressing Add-in-registration task during build process

Mon, 16 May 2011 07:17:00 +0200

If you develop ArcGIS Add-ins with Visual Studio under limited permissions you get during the build process an error, that the stuff could not be registered.

Normally its enough to run one times this build as an admin. Then all needed information are set and also taken for users with limited access.

Casing of COM-Interop registered components

Tue, 08 Jun 2010 09:54:00 +0200

During a refactoring i realized that renaming of components, which will be registered for COM-Interop, must be done carefully.

In my case i changed the casing of XyzToolbar to XyzToolBar.

At the developing machine everything works fine. But after installing the modified stuff at the production machine, the toolbar was not visible. Using regasm with the new assemblies helped.

F# and ArcObjects, Part 3

Fri, 26 Mar 2010 13:15:00 +0100

Today i played a little bit with IFeature-sequences and piping data. The result was a calculator of the bounding box around all features in a feature class.

Maybe a little bit dirty, but for learning was it OK. ;-)

F# and ArcObjects, Part 2

Thu, 25 Mar 2010 14:49:00 +0100

After accessing one feature now i iterate through all features of a feature class:

open System;;

#I "C:\Program Files\ArcGIS\DotNet";;
#r "ESRI.ArcGIS.System.dll";;
#r "ESRI.ArcGIS.DataSourcesGDB.dll";;
#r "ESRI.ArcGIS.Geodatabase.dll";;
open ESRI.ArcGIS.esriSystem;;
open ESRI.ArcGIS.DataSourcesGDB;;
open ESRI.ArcGIS.Geodatabase;;

let aoInitialize = new AoInitializeClass();;

let status = aoInitialize.Initialize(esriLicenseProductCode.esriLicenseProductCodeArcEditor);;

let workspacefactory = new SdeWorkspaceFactoryClass();;

let connection = "SERVER=okul;DATABASE=p;VERSION=sde.default;INSTANCE=sde:sqlserver:okul;USER=s;PASSWORD=g";;

let workspace = workspacefactory.OpenFromString(connection, 0);;

let featureWorkspace = (box workspace) :?> IFeatureWorkspace;;

let featureClass = featureWorkspace.OpenFeatureClass("Praxair.SFG.BP_L_ROHR");;

let queryFilter = new QueryFilterClass();;

let featureCursor = featureClass.Search(queryFilter, true);;

let featureCursorSeq (featureCursor : IFeatureCursor) = 
 let actualFeature = ref (featureCursor.NextFeature())
 seq {
 while (!actualFeature) <> null do
 yield actualFeature
 do actualFeature := featureCursor.NextFeature()
 };;


featureCursorSeq featureCursor
 |> Seq.iter (fun feature -> Console.WriteLine ((!feature).OID));;

F# and ArcObjects, Part 1

Thu, 25 Mar 2010 10:58:00 +0100

After having a first look on F# its time to ask: How could i use F# with ArcObjects.

So my first steps was to do something with a feature in a F# interactive session. And these are my first code lines:

Nachtrag: Casting Anti-Pattern

Thu, 29 Oct 2009 12:40:00 +0100

Wie so oft im Leben sind manche Dinge auf den zweiten Blick komplexer als sie auf dem Ersten den Anschein haben.

Es kam die Anfrage, ob es nicht doch einen Unterschied zwischen “as” und “is” gibt & dann wurden noch ein paar Inputs gefunden, dass im Falle des “Überladens von Cast-Operatoren” mögliche Fallen lauern.

Casting Anti-Pattern

Thu, 29 Oct 2009 12:35:00 +0100

in unten stehendem Code ist ein Anti-Pattern, welches immer wieder im ArcObjects-Kontext zu beobachten ist.

if (element is IMapSurroundFrame)
{
 IMapSurround mapSurround = ((IMapSurroundFrame)element).MapSurround;
 ..

Es wird eine is-Abfrage gemacht (element is IMapSurroundFrame) und dann ein Stück später der tatsächliche Cast ((IMapSurroundFrame)element).

Catching COM-Exceptions from ArcObjects

Tue, 20 Oct 2009 14:36:00 +0200

to catch the COM-Exception in own applications thrown from the underlaying ArcObjects-Library could be done with:

catch (COMException ComEx)



 Console.WriteLine(string.Format("MyCode errored: {0}, Error Code: {1}",



 ComEx.Message, ComEx.ErrorCode));

the special error constants could be found under: