Programming for Geographical Information Analysis: Advanced Skills

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Programming for Geographical Information
AnalysisAdvanced Skills

• Lecture 2 ArcObjects Framework
• Dr Andy Evans

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• AddIn Architecture
• ArcObjects Framework

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Java

• Direct access to ArcObjects Framework inside and
  outside Arc.
• Ability to add components to the GUI.
• Ability to communicate with external applications.

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AddIns

• Button Icon on toolbar.
• Tool Changes mouse operations.
• Combo box Dropdown list and editable box.
• Toolbar For grouping AddIns.
• Menu Dropdown and right-click.
• Tool palette Floating container for other
  AddIns.
• Dockable window Floating window that can be
  locked into the GUI.
• Application extension Additional functionality
  within, e.g. Arc extensions.

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Form

• jar zip file, with a .esriaddin extension
• Contains
• config.xml metadata describing the addin
• Java class files
• Other resources needed e.g. data, images

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Installing

• File is just dropped into
• USERPROFILE\
• My Documents\ArcGIS\AddIns\Desktop10.2 
• or
• USERPROFILE\
• Documents\ArcGIS\AddIns\Desktop10.2
• There are easy install options for users (double
  clicking on the addin will bring up a wizard to
  walk through installing it)

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Installing a sent AddIn

• AddIn Manger

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Installing a sent AddIn

• Choose Add from file and navigate to the file.
• Should then see it under the commands list in
  whatever Category youve created for it in the
  XML file.
• Drag and drop from here, onto the interface.

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Managing AddIns

• Admin Registry Keys (regedit.exe)
• HKEY_LOCAL_MACHINE\SOFTWARE\ESRI\Desktop10.2 \
  Settings
• BlockAddIns
• 0 - Load all.
• 1 - Load signed only.
• 2 - Load ESRI only.
• 3 - Load from administrator folders only.
• 4 - Do not Load any Add-Ins.
• AddInFolders
• AdminAddInLock - stop tampering with these.

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Digital signing

• See
• http//help.arcgis.com/en/sdk/10.0/Java_AO_ADF/con
  ceptualhelp/engine/index.html/Digitally_signed_ad
  d_ins/0001000004zq000000/

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Making an AddIn

• Rather than writing the config.xml ourselves, and
  zipping it up manually with the java files,
  theres an Eclipse IDE plugin.
• This does all the basic class generation for us,
  and prepares the file.
• Details for installing the IDE and plugin on the
  website.

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Eclipse
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Eclipse
Project area
Editor area, currently showing config.xml, but
shown as a form, not text.
Show xml text source
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Config.xml
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Eclipse

• Should check code as you write.
• Will compile when you save the file.
• Errors reported in problems panel
• Note that the javadoc panel displays the javadocs
  of known classes.

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Eclipse

• Will autocomplete as you type. Will also suggest
  potential quick fixes if you click on hover over
  an issue.

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Debugging

• No System.out.println()
• Best bet is
• JOptionPane.showMessageDialog(null, String)
• E.g.
• JOptionPane.showMessageDialog(null, "Hello
  World")
• Or for exception checking
• catch (Exception e)
• JOptionPane.showMessageDialog(null,
  e.getStackTrace())

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Help coding

• Course Code Cookbook
• Theres no point in you struggling to find key
  bits of code on ESRIs site.
• So, there are many useful code examples,
  stripped down to be a simple as possible, on the
  course website.
• The quid pro quo
• Send us useful code you get working.
• Read and try and understand the code, dont just
  cut- and-paste it. Ask questions!

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Help coding

• Intro to Eclipse
• Help -gt Welcome -gt Overview / Tutorials
• Arc Programming pages
• http//resources.arcgis.com/en/help/arcobjects-jav
  a/concepts/engine/
• Java ArcObjects Developer Guide -gt
• Developing extensions -gt
• ArcGIS Desktop customizations using add-ins

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Help coding

• API
• http//resources.arcgis.com/en/help/arcobjects-jav
  a/api/arcobjects/index.html
• Note that the API docs are a re-write of the VB
  pages, and still contain some VB code
• If it says This parameter is optional, it
  usually isnt.
• If it says If you dont want this parameter,
  just pass in zero or Nothing, then pass in
  null.
• If it gives Variant as a return type, it returns
  java.lang.Object.

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Select the AddIn
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If you are developing, you need to reboot Arc to
get changes to appear, but you dont need to
re-add the addIn.
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Extensions

• Classes that extend Arc functionality
• Custom feature renderers
• Custom geoprocessing tools can be added to
  ArcToolbox and ModelBuilder
• Class extensions Change form of data
• Plug-in data sources
• Utility objects Combine other tools

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Installing

• Jar file placed in
• ltArcGIS Install Dirgt/java/lib/ext

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• Programming ArcGIS
• AddIn Architecture
• ArcObjects Framework

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Code

• The code that goes in the addIn is then code to
  work with the ArcObjects framework.

The running version of Arc is accessed via
gatekeeper objects. You then request objects
from these, and subsequent objects from the
objects you get back.
Ask App for Document Ask Document for Maps Ask
Maps for a Map Ask Map for Layers Ask Layers for
Layer etc.
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init(IApplication app)

• Most addIns come with a init method that can be
  overridden. This is sent the application as an
  entry point for the running framework.
• import com.esri.arcgis.framework.
• private IApplication app
• _at_Override
• public void init(IApplication app)
• this.app app

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Document

• You can use this to get hold of the current
  document. This is the current data and GUI.
• import com.esri.arcgis.arcmapui.
• IMxDocument mxDoc (IMxDocument)app.getDocume
  nt()

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API

• It is then just a matter of finding how to do
  stuff in the API docs
• http//resources.arcgis.com/en/help/arcobjects-jav
  a/api/arcobjects/index.html

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N.B.

• The code utilises Java Annotations.
• _at_name
• Used as a marker for software intending to
  process the code.
• _at_Override

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N.B.II

• Arc returns objects that implement multiple
  interfaces.
• You generally cast the object to a specific
  interface when using it.
• IMxDocument mxDoc (IMxDocument)app.getDocume
  nt()
• There is nothing to stop you recasting it to
  another interface to use different methods in it
• IDocument iDoc (IDocument) mxDoc
• Infact, it is very common.

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The COM

• In Microsoft languages, this reassignment of
  interface labels is key.
• It allows chunks of code to use other chunks of
  code without knowing anything other than the
  interface names.
• It is used to hold together a great deal of the
  Component Object Model (COM) at the heart of
  Microsoft software.
• ArcGIS is built around the COM, so this is a
  common thing to see.

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Interfaces

• This requires some care.
• You might think that redefining everything as the
  right object would be sensible
• public void init(IApplication app)
• Application a (Application)app
• You could then use all the methods.
• However, while objects Arc gives you will match
  the interfaces, they may not do anything sensible.

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Interfaces

• For example, this works in ArcMap
• public void init(IApplication app)
• Application a (Application)app
• IGxSelection selec a.getSelection()
• JOptionPane.showMessageDialog
• (null, selec.toString())
• But doesnt give you anything sensible, as
  IGxSelection is an ArcCatalog class, and here the
  Application object is the ArcMap Application
  object, not the ArcCatalog one.

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Interfaces

• In general, better to get the interface right and
  keep the object defined by its interfaces.
• As well as explicitly casting, just attaching the
  right label works if you are going to a less
  specific class
• IMxDocument mxDoc app.getDocument()
• But generally in the examples youll see an
  explicit cast because it saves looking up the
  relationship.
• In the API Docs, in general go for the interface
  list at the top of the class.
• Interfaces generally start I
• Then Mx for ArcMap, Gx for ArcCatalog.

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ArcMap IApplication methods

• newDocument(boolean userPickTemplate?, String
  path)
• openDocument(String optionalPath)
• refreshWindow()
• saveDocument(String optionalPath)

If the paths are null, the usual new, open,
and save processes occur.
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ArcMap IMXDocument methods

• Used for getting data
• getActiveView() i.e. layout view or data view
  data.
• getFocusMap() i.e. currently selected/shown
  map.
• getMaps() i.e. all maps.
• getSelectedItem() i.e. that the user has picked.
• getSelectedLayer() i.e. that the user has picked.
• Documents also implement IDocument, the main use
  of which is programmatically controlling toolbars.

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Next Lecture

• Getting, sorting, and searching data.
• Practical
• Hello World!
• Utilising tools in Arc Addins.