VBA and ArcObjects Programming

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VBA and ArcObjects Programming

• Week 1
• Spring 2008
• Advanced GIS

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Why learn programming ?

• Because, there are three types of GIS jobs in the
  market....
• Logon to monster.com and type GIS programmer
• And you will find the pay scale.

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Object-Oriented Programming

• Object has property and behaviors (methods). Lots
  of objects are buttons, tools, windows, and
  dialog boxes.
• Object.Method
• Table.AddRecord
• Tree.Grow(10) /argument, parameter
• Tree.Create /first create a tree, then
• Tree.GrowBranch /then, grow branch from the tree
• Branch.GrowApple /apple grown from branch.
• Boy.Eat(AnApple)

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Visual Basic for Application (VBA)

• A simplified version of Visual Basic, loaded with
  ArcGIS, embedded within applications.
• Use functions in ArcGIS
• Code organized in Procedures a procedure
  includes instructions. Procedure can be linked to
  each other, by calling others. Events makes
  procedure run.

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ArcObjects and ArcGIS

• ArcMap and ArcCatalog are built with ArcObjects
• Each GIS part is a programmable object
• Users and programmers use same objects
• Data frames, layers, features, tables, symbols,
  points, lines, polygons, records, fields, colors
  --------are ArcObjects

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ArcObjects

• There are 2,700 classes and 2,000 interfaces
  documented in several object model diagrams.
• With such extensive collection of classes, you
  can create many customized applications to extend
  ArcGISs functions.
• Where to begin with? is the major difficulties
  faced by GIS programmers.
• Problem solving strategy help you glide through
  the real-world ArcObjects programming tasks.
• Three parts of problem-solving guides

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I Define the ArcObjects Programming Tasks
II Locate the correct object model

• Identify a subtask
• Extract keywords
• Search for the correct object model diagrams
• Review all related documentation

• Describe the problem in ArcObjects terms
• Identify subtasks
• Decide where to write the code
• Search for a related sample of recommended
  methodology

III Navigate the object model diagram

• Review the structure of the object model diagram
• Trace the flow between classes and assemble code

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Describe the problem in ArcGIS terms

• For example Add a dataset called States to
  ArcMap can be described as
• Access the States feature class from a personal
  geodatabase and add it to ArcMap.
• A two-step approach illustrate the procedures.

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Customize Toolbars

• Open a ArcMap screen (Start Programs ArcGIS
  ArcMap)
• You want to start with A new empty map.
• Add theme from c\esri\esridata\usa\ (STATES,
  Drainage, lakes, rivers and roads)
• Once your themes are in the project, practice the
  functions of ArcMap (
• Zoom In/Out,
• Pan,
• Select Feature,
• Identify,
• Measure ? (you may get degrees as distance)
  change DataFrame Properties setting of Display
  Unit to Miles

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Showing/Hiding toolbars

• Double-click any unoccupied area of any toolbars
  to display the Customize dialog box (or from
  ToolsCustomize..)
• The presence of a check mark next to the toolbar
  name indicates it is present.
• In the Toolbars tab of the Customize dialog ,
  click New. In the Tools Name area type in My
  personal tools and Save in Untitled (since you
  havent saved your project yet). If you save the
  personal tool into Normal.mxt, then it will
  become a default tool for everyone who use this
  machine. We dont want to do so. Simply save it
  to Untitled to avoid confusion to other users.
• Click OK

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Adding more tools to your personal tool box

• Adding buttons and menus to your personal tool by
  selecting commands (click Command tab to switch
  to Command window) dragging to My personal
  tools toolbar. With category of Selection open
  (Command Selection), drag commands to My
  personal tools (drag Buffer Selection and
  Hyperlink to the window, if Category is
  Selection)
• Practice putting different menu and commands on
  your personal toolbar. You can also remove them
  by dragging out of the box.
• Click Close to close the customize window.
• Save file in your own folder (if you dont have
  one, create one in G drive)

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Writing Macros in VBA

• You can use VBA integrated development
  environment (IDE) to create macros to help you
  automate tasks you perform repeatedly
• With the VB Editor you can edit macros, copy
  macros from one module to next, rename modules
  that store macros.
• Click the Tool menu, point to Macros, then click
  Macro. In the Macro dialog, type MyZoomIn as name
  and click Create (this will take you to the VB
  screen and you are ready to create a customized
  tool)

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Code window

• Sub MyZoomIn()
• '
• ' macro MyRoomIn
• '
• Dim pDoc As IMxDocument
• Dim pEnv As IEnvelope
• Set pDoc ThisDocument
• Set pEnv pDoc.ActiveView.Extent
• pEnv.Expand 0.5, 0.5, True
• pDoc.ActiveView.Extent pEnv
• pDoc.ActiveView.Refresh
• End Sub
• Envelopes are the rectangular window that contain
  a specific element.  All Geometry objects have an
  envelope defined by the XMin, XMax, YMin, and
  YMax of the object.  Envelopes can also serve as
  the viewing area for a particular view screen or
  data frame.

ArcMap Doc
ThisPredefined variable-is the Idocument
interface to the MxDocument object
ActiveView property provides an IActiveView
interface that links the document data to the
current screen display of that data
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Run Macro

• Go to File Close Return to ArcMap
• In ArcMap, go to ToolsMacro and select
  Module1.MyZoomIn macro and click Run (make sure
  your macro settings is in Normal) (Alt F8)
• The display zoomed in 50 smaller.

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Add Macro to a toolbar

• Go to Tools Customize.
• In the Toolbar tab, make sure My personal Tool
  is still there
• Click Command tab and select Macros category.
  Select your macro (MyRoomIn) and drag to My
  Personal Tool bar
• A default icon appears. To change image,
  right-click on this icon and a context menu
  shows, go to Change Button Image and select one
  from the panel (smiling face,ok?)
• Close the Customize dialog box
• Click the smiling face to run the macro

Right-click on smiling face, select View Source
to modify your code to 0.75 from 0.5 for zoomin
ratio
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Exercise - 1

• Create a new Macro named MyRoomOut in Module1
• Hint copy code from codewindow (from the
  beginning of the Sub to the End Sub, and paste
  below the existing code. Rename the copied Sub
  to MyZoomOut and change line
• pEnv.Expand 0.5, 0.5, True to
• pEnv.Expand 2.0,2.0,True
• Add this macro to My Personal Tool and run it

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UIControls User Interface Controls

• UIButton - Save
• UITool - Pan
• UIComboBox
• UIEditBox
• Code is required for UI to work.

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Project, Code module and Procedure
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Project/Code Module/Procedure

• 3 types of projects
• Map documents (.mxd)
• Base templates (.mxt)
• Normal template (Normal.mxt)
• Code modules
• ThisDocument, you may write code for any
  UIControls that you make in a particular project
• Procedure
• Code is organized into procedures

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Procedures

• 4 types of procedures
• Event, subroutine, function and property
• Event correspond to user actions, such as
  Click, which will execute the codes once it is
  clicked and three other types of codes will be
  called to work
• Public/Private Private procedure can only be
  called within same code module where Public
  procedures can be called by other code modules.

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InputBox/MsgBox

• InputBox and MsgBox are two fundamental message
  receiving and conveying methods used in the
  beginning of this class.
• Inputbox (Message here, Title Here.)
• MsgBox (Message Here, Title here)
• You may not use () for these boxes