Programming with Avenue

1
Programming with Avenue

• CEEN 514
• Civil Engineering Application of GIS
• BYU

2
Object model diagram
3
Object model diagram
4
Avenue scripts

• An object-oriented programming language
• Custom ArcView applications are created with
  AvenueTM scripts.
• Scripts are written, compiled, tested and
  debugged from the ArcView Script Editor document.

5
Script Editor

• ArcView document used to write, compile, run,
  debug, and edit scripts
• Like other documents, the Script Editor has a
  unique set of menus, and buttons

6
Creating your first script

• Step 1 Enter the code into the script window
• Step 2 Compile the script
• Step 3 Test and debug as necessary
• Step 4 Save the script

7
Typing and Loading

• Start writing Avenue code by typing directly into
  a Script window.
• Its a good habit to add comments in your code.
  An apostrophe indicates a comment in Avenue.
• You can also use a text editor to type your
  Avenue code into an ASCII text file, then load
  the text file into a Script window.

8
Compiling, Testing, Debugging, and Saving

• Use Compile button to compile the script
• Use Run button to execute and test the script
• The Examine Variables button displays a
  window showing the variable type, name, class and
  value
• Scripts can be saved with your current project.
  You can also save scripts as text files to store
  them separately

9
Customizing the user interface

• The customize dialog box is the visual interface
  you use to customize the documents GUIs.
• The individual menu choices, buttons, and tools
  are called controls.
• With the Customize dialog box you can move, add,
  delete or change properties of the controls.

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The Customize dialog box

• To open the Customize dialog box, choose
  Customize in the Project menu, OR
• Double-click on any blank space on the button or
  tool bar

11
Assigning a script to a control

• In the Customize dialog box, use the Properties
  List to assign a script to a control.
• Double-click an event property to display the
  Script Manager, and choose the script that will
  execute when the event occurs.
• The Script Manager is a dialog box listing all
  scripts that are currently available in the
  project.
• Menu choices, buttons, and tools all have a Click
  property. Tools also have an Apply property.

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Objects, classes, and requests

• An object is a package of properties and requests
• Objects are elements you work with in ArcView,
  such as views, themes, GUIs controls, and
  graphics.
• Objects can also be things like number, strings,
  and dates.

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Classes how objects are defined

• A class is a template for building objects
• Each class defines a unique set of requests and
  properties
• Instances are objects created from the same class
  all share the same request and properties
• View class View1, MyView are instances

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Requests

• Create objects, retrieve objects, and check or
  change properties
• Create new objects (class requests)
• myView View.Make
• Retrieve Objects (instance requests)
• myView aProject.FindDoc(View1)
• Check and change property values
• myView.SetName(Atlanta)

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Avenue online help

• The Avenue online Help system gives detailed
  explanations of classes and requests.

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Constructing Avenue Statements

• Send a request to an object
• General statement Object.RequestRequest
• av.GetProject.FindDoc(View1).FindTheme(City)
  
• Requests can require parameters
• myView.SetName(Atlanta)
• Statement with numbers Object Request Object
• 15 20
• theValue 100

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Assignment statements

• A request sent to an object returns another
  object
• Assign a variable to the returned object
• aTheme av.GetProject.FindDoc(World).FindTheme
  (GNP)
• Assign variables directly
• CompanyTitle Environmental Modeling Research
  Laboratory
• aConstant 1.5
• Assign local or global variables
• myLocalVar 25 23
• _myGlobalVar myValue 37

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Variable rules

• Not declared or typed
• Must begin with a letter or underscore
• Not case-sensitive
• Avenue compiler finds conflicts with reserved
  names
• View av.GetProject.FindDoc(Redlands)
• A local variable is available only in the script
  in which it is assigned
• Global variable names are preceded by an
  underscore (_) and are available to all scripts

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Using strings

• Concatenate strings
• theNewString Good MorningMichael
• Good Morning Michael
• theNewString Good MorningMichael
• Good MorningMichael
• Newline, tab, and carriage return NL, TAB, and
  CR
• theNewString Good MorningNLMichael
• Good Morning
• Michael
• String conversions
• myNumber string1.AsNumber
• newDate myString.AsDate

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Using numbers

• Numeric evaluation is left to right, unless
  parentheses are used
• x 2 3 3 x 15
• x 2 (3 3) x 11
• Mathematical operations
• wholeNumber 35.689.Round returns 36
• Number formatting
• myNumber.SetFormat(d.dd)
• Number conversions
• numRadians 90.AsRadians
• numDegrees numRadians.AsDegrees

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Example Avenue script

• Start ArcView and open example project
• Open script Example01
• Compile and run the script
• Examine variables during script execution
• Save the script to a text file
• Modify the View menu and button bar
• Assign the script to a control
• Save and close the project

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Working with a View

• Creating a new view
• aView View.Make
• aView.SetName(aName)
• aView.GetWin.Open
• Getting a view
• aView av.GetActiveDoc
• aView av.GetProject.FindDoc(aViewName)

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Adding a theme to a view

• Create a data source name
• from a shapefile
• dataSrc SrcName.Make(c\avdata\streets.shp)
• Create the theme
• theTheme Theme.Make(dataSrc)
• Add the theme to a view
• theView av.GetProject.FindDoc(Redlands)
• theView.AddTheme(theTheme)

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Working with a theme

• Getting a theme from a view
• aView av.GetProject.FindDoc(aViewName)
• aTheme aView.FindTheme(aThemeName)
• Making a theme visible
• aTheme.SetVisible(TRUE)
• Changing the name of a theme
• aTheme.SetName(aThemeName)

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Example VwThm01

• creates a view
• add themes to a view

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Example VwThm02

• changes the name of a view
• changes the name of a theme

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Working with tables

• The role of virtual tables (VTabs)
• How a table and a Vtab are associated
• Getting a Vtab or an Ftab
• Modifying fields and field values
• Using a bitmap for managing selections

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Table and VTab classes

• A Table is a type of document for viewing tabular
  data
• Each table has an associated virtual table (VTab)
• A VTab manages the data sources
• supports the viewing of multiple data sources
  as one
• Each VTab is composed of zero or many fields
• The VTab has a selection bitmap
• FTab supports tables that are associated with
  themes. FTab is a type of VTab, and therefore
  performs the same operations

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Creating a table from an existing data source

• Convert the pathname to a FileName
• theFN c\data\offices.txt.AsFileName
• Create a VTab and a Table
• Vtab.Make(aFile, isWritable,skipRecord)
• theVTab Vtab.Make(theFN, fasle,false)
• myTable Table.Make(theVTab)
• Get the table window and open it
• myTable.GetWin.Open

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Getting a Vtab or an Ftab

• Getting a Vtab from a table
• aTable av.GetProject.FindDoc(aTableName)
• aVtab aTable.GetVtab
• Getting an Ftab from a theme
• aView av.GetProject.FindDoc(aViewName)
• aTheme aView.FindTheme(aThemeName)
• anFtab aTheme.GetFtab

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Working with fields

• Returning fields
• fieldList theVTab.GetFields
• Getting a field
• firstField fieldList.Get(0)
• myField theVTab.GetActiveField
• myField theVTab. FindField(City)
• Getting the field type
• theFieldType myField.GetType
• Setting an alias name or visibility
• myField.SetAlias(Zoning Code)
• myField.SetVisible(True)

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Updating record values

• Get the Vtab and set it editable
• theVTab av.getProjectFindDoc(Table1).GetVtab
  
• theVTab.SetEditable(True)
• Get the field and update its value for a record
• nameField theVTab.FindField(Name)
• idField theVTab.FindField(ID)
• theValue theVTab.ReturnValue(idField, 3)
• theVTab.SetValue(nameField, 3, newName)
• Update the document
• theVTab.Refresh

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Calculating field values

• Get the Vtab and the field to calculate
• theVTab av.GetActiveDoc.GetVTab
• theField theVTab.FiendField(Total_Tax)
• Create an expression
• theExpression FieldName1 FieldName2
• Calculate the new field value
• theVTab.Calculate(theExpression, theField)
• theVTab.Refresh

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Creating a selection bitmap

• A selection bitmap flags each record as selected
  or not selected
• theBitmap aVtab.GetSelection
• theBitmap anFtab.GetSelection
• Clearing selection
• theBitmap.ClearAll
• Getting counts on the bitmap
• totalBits theBitMap.GetSize
• selBits theBitMap.Count

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Processing records

• Process all records in the Vtab
• for each rec in aVTab
• do something
• end
• Process all selected records in the bitmap
• for each rec in aVTab.GetSelection
• do something
• end

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Summing selected records

• Get the VTab, the field, and the bitmap
• theVTab theTable.GetVTab
• theField theVTab.FindField(Area)
• theBitMap theVTab.GetSelection
• Sum the area for the selected records
• sum 0
• for each rec in theBitMap
• val theVTab.ReturnValue(theField, rec)
• sum sum val
• end
• Report the results
• MsgBox.Info(Total area issum.AsString,Stat
  istics)

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Example TblVtab01

• Find a table
• Get the Vtab
• Find a field
• Calculate field values

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More work with tables

• Summarizing a table (Vtab or Ftab)
• Joining two tables (Vtab or Ftab)
• Creating a new database file and a table
• Querying a table (Vtab or Ftab)

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Summarizing a table (Vtab or Ftab)

• Get the Vtab/Ftab and a field
• aFtab aTheme.GetFtab
• stateFld aFtab.FindField(StateName)
• Summarize area and create a new database file
• aFTab.Summarize (aFileName, aClass, aField,
  Fields, Summarys)
• aFTab.Summarize( States".AsFileName, dbase,
  stateFld,
• areaFld,VTAB_SUMMARY_SUM )
• To count the number of occurrence only
• aFTab.Summarize( States".AsFileName, dbase,
  stateFld, ,)

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Joining two tables (Vtab/Ftab)

• Get both tables
• aFTab aTheme.GetFtab
• aVtab aTable.GetVtab
• Find fields
• fldFtab aFtab.FindField(fldFtabName)
• fldVtab aVtab.FindField(fldVtabName)
• Joining two tables
• aFTab.Join (aToField, aFromVTab, aFromField)
• aFTab.Join (fldFtab, aVTab, fldVtab)
• Removing join
• aFTab.UnjoinAll

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Creating a new database and table

• Create source file and table
• theVTab VTab.makeNew(emplyees.dbf.AsFileName
  ,dbase)
• myTable Table.make(theVTab)
• Add two fields
• field1 Field.Make(ID,FIELD_SHORT,5,0)
• field2 Field.Make(Name,FIELD_CHAR,10,0)
• theVTab.AddFields(field1, field2)
• Add ten records and set initial values
• for each i in 1..10
• rec theVTab.AddRecord
• theVTab.SetValue(field1, rec, i)
• end

42
Querying a table (Vtab/Ftab)

• Getting the Ftab and the Bitmap
• aFTab aTheme.GetFtab
• aBitMap aFtab.GetSelection
• Writing an query expression
• theQuery StateNameaStateName.Quote
• Querying and updating selection
• aFtab.Query(theQuery, aBitMap,
  VTAB_SELTYPE_NEW
• aFtab.UpdateSelection

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Example Summarize01

• Summarize a shapefile based on a field and thus
  create a new dbase file
• Create a table from the new dbase file

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Example GetInfo01

• Join a Vtab with an Ftab
• Calculate a field in Ftab using joined fields

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Example CrtDbfQuery01

• Create a new dbase file and add fields
• Get information from a Ftab
• Query another Ftab and find totals
• Add records in the new dbase file and set values
  in the fields.

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Dialog Designer

• CEEN 514
• Civil Engineering Application of GIS
• BYU

47
What is a dialog

• A dialog is another user interface tool you can
  use to build applications in ArcView
• Create your own input forms
• Organize related tools in separate windows
• Link whats displayed in a dialog directly to
  your data
• Add buttons directly to a View or Layout

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How does the Dialog Designer work?

• Load Dialog Designer extension into ArcView. You
  will notice a new document in the project window.
  
• Double click the icon and youll create a new
  dialog editor document.
• All of the interface components, controls, you
  can add to your dialogs are located on the tool
  bar.
• Once you have added controls to the dialog,
  youll write scripts that make it work. Then,
  youll attach your dialog to ArcViews interface
  so people can use it

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Dialog Designer document
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Creating a dialog and adding a control to it

• Load the Dialog Designer extension
• Start ArcView and bring up the Extension Manager
  dialog. Check Dialog Designer and press OK.
• Create a dialog document
• Double-click on the Dialogicon in the
  project window
• Add controls to a dialog
• Select a control button from the tool bar, then
  click and drag out a rectangle on the dialog
  inside the dialog frame

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Creating a dialog and adding a control to it
(contd)

• Set the control properties
• Display the label buttons properties by
  double-clicking it on the dialog. In the Name
  field, type in the name. To change the label,
  double-click on the Label property and type in.

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Creating a dialog and adding a control to it
(contd)

• Attach a script to the control
• Locate the Click property and double-click to
  display the script manager dialog. Select the
  script and press OK.

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Creating a dialog and adding a control to it
(contd)

• Compile and run the dialog
• Make the dialog the active document
• Press the Compile button
• Press the Run button

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Attach the dialog to the interface

• At this point, you can run the dialog by
  pressing the Run button. But, youll likely want
  to attach the dialogs you create to ArcViews
  interface.
• Create the following script and attach to a
  button on the ArcViews button bar.
• aDialogName.Run
• Runs the dialog.
• Av.GetProject.FindDialog(aDialogName).Open
• If your dialogs are loaded from an extension, use
  following request.
• Av. FindDialog(aDialogName).Open

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Whats next?

• Depending on your application, there are several
  ways to distribute your custom dialogs.
• You can save those in a project.
• If youll be using your dialogs with different
  projects or you plan to distribute them to
  others, you can create an ArcView extension.

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Example Dialog Designer

• Load the Dialog Designer extension
• Create a dialog
• Add controls
• Change properties of the control
• Write script and attach to the control
• Compile and run
• Attach dialog to the interface

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Advance Avenue

• CEEN 514
• Civil Engineering Application of GIS
• BYU

58
The Application Framework

• When ArcView starts, the application is created
• Reference the application with the keyword av
• A one-to-one association exists between
  application and project
• av.GetProject
• Multiple associations between Project and Doc,
  Project and DocGUI
• av.GetProject.FindDoc(World)
• A one-to-one association exists between Doc and
  DocWin, Doc and DocGUI
• av.GetProject.FindDoc(World).GetWin

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Working with the application

• Window properties
• av.MoveTo(20,20)
• av.Resize(800,600)
• av.TileWindows
• Active document and window
• theActiveDoc av.GetActiveDoc
• theActiveWin av.GetActiveWin

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Controlling the status bar

• Display a message in the status bar
• av.ShowMsg(Creating themes)
• av.ClearMsg
• Move the progress bar or stop progress
• for each i in 0..100
• av.SetStatus(i)
• end
• av.ClearStatus

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Executing a script from another script

• Use the application with the Run request
• Pass any object into the called script
• In the called script, use SELF to refer to the
  passed object
• Use the Return statement to send an object back

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Working with the project

• Create, name, and save a project
• theProject Project.Make
• theProject.SetFileName(world.apr.AsFileName)
• theProject.Save
• Open and close a project
• theProject Project.Open(world.apr.AsFileName)
  
• theProject.Close
• Manage documents in the project
• theView theProject.FindDoc(Asia)
• theProject.SetActive(theView)
• theProject.RemoveDoc(theView)

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Example Application and Project

• Start ArcView and open a project
• Modify the application window
• Customize the status bar
• Change the name of a project
• Write a script that runs another script
• Manage documents in a project

64
Branching and looping

• Branching statements
• IfThenElse
• Boolean expressions
• Check a condition for true or false
• Looping statements
• For Each
• While
• Collections
• Lists
• Dictionaries

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IfThenElse statement

• Conditional branching
• if (Boolean expression) then
• do something
• else
• do something else
• end
• Example verify a password
• thePWord MsgBox.Password
• if (thePWord cheddar) then
• av.GetProject.FindDoc(LA Banks).GetWin.Open
• else
• MsgBox.Info(Sorry, incorrect
  password,Password)
• end

66
Boolean objects and expressions

• There are two Boolean objects true and false
• Assign directly or return from a request
• done false
• status theTheme.IsVisible
• Place Boolean expressions in parentheses
• (yourNumber gt 36)
• Create compound expressions with and,or, or not
• ((yourResponse yes) and (yourNumber gt 36))

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While statement

• Performs a set of requests while a condition is
  true, the loop stops when a condition is false
• While (condition)
• some request here
• condition must change
• end
• Example sum a set of numbers
• While (start)
• if (thevalue ltgt nil) then
• sum sum theValue.AsNumber
• else
• start false
• end
• end

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For Each statement

• Applies a set of requests to each object in a
  collection
• for each anObject in aCollection
• request block
• end
• Turn on each theme in the view
• theThemeList theView.GetThemes
• for each thm in theThemeList
• thm.SetVisible(true)
• end
• Intervals and increments
• for each num in 0..10 by 2
• sum sum num
• end

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Lists

• A group or collection of objects
• Create a list
• myList theCompany, Phone, 157.50
• theThemeList theView.GetThemes
• newList List.Make
• Add objects to a list
• theNames.Insert(City)
• theNames.Add(Streets)
• Reference objects in a list
• myList theCompany, Phone, 157.50
• theName myList.Get(0)
• myList.Remove(2)

70
Dictionaries

• A dictionary is a collection of unique key and
  value pairs
• KEY VALUE "Utah" "Provo", "Orem", "Salt lake
  City
• Create and add elements
• usStateCity Dictionary.make(52)
• usStateCity.Add(Utah, Provo,Orem,Salt
  Lake City)
• Retrieve dictionary entries
• theStateList usStateCity.ReturnKeys
• UtahCities usStateCity.Get(Utah)

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Continue, Break, and Exit

• Alters the normal flow control
• Continue skips the current iteration of the loop
• Break causes immediate exit from the loop
• Exit immediately terminates the script

for each num in 1..4 if (num 3) then
continue end sum sum num end sum 7
for each num in 1..4 if (num 3) then
break end sum sum num end sum 3
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Example Branching and looping

• Creating and displaying list of themes
• Toggle theme visibility
• Design a customer data input form
• Use a dictionary to store customer data

73
Themes and legends

• Setting theme symbology
• Theme selection
• Theme analysis

74
Setting theme symbology

• Get a list of legend symbols
• theLegend theTheme.GetLegend
• theLegendSyms theLegend.getSymbols
• Get the Symbol window and the Color Palette
• thePalette av.GetSymbolWin.GetPalette
• theColors thePalette.GetList(PALETTE_LIST_COL
  OR)
• Set symbol color
• firstSym theLegendSyms.Get(0)
• firstSym.SetColor(theColors.Get(4))
• Redraw legend
• theTheme.InvalidateLegend
• Turn the theme on
• theTheme.SetVisible(true)

75
Shuffling themes in the TOC

• Get the view and theme list
• theView av.GetActiveDoc
• theThemeList theView.GetThemes
• Shuffle the first theme to the bottom
• theTheme theThemeList.Get(0)
• theThemeList.Shuffle(theTheme,theThemeList.Count)
  
• Redraw all theme
• theView.InvalidateTOC(nil)

76
Selecting theme features

• Get the feature table and the feature selection
• theView av.getActiveDoc
• theTheme theView.FindTheme(nwtracts)
• theFTab theTheme.GetFtab
• theSelection theFTab.GetSelection
• Create a logical expression
• theExpression (med_hh_in gt 60000)
• theFTab.Query(theExpression, theSelection,
• VTAB_SELTYPE_NEW)
• Highlight the new selection in the view and table
• theFTab.UpdateSelection

77
Example Themes and Legends

• Create a theme from a shapefile
• Change the symbols
• Shuffle the themes
• Build an expression to select features