GEOG 485 GIS Programming and Customization

Transcription

1 Overview of Project 1 The first three parts of Lesson were surprisingly easy. I come to GEOG 485 with no programming background or experience. In the month preceding this course I worked through the first three modules of the ESRI Learning Visual Basic for Applications for New ArcGIS Developers course and the first seven chapters of Getting to Know ArcObjects. That gave me enough of a taste of visual basic that Parts 1-3 of this course were clearly understandable and easy to follow. Reality hit with part 4. The move from following step by step instructions to creating code, even simple code that mimics what the earlier steps demonstrated, proved challenging. I was able to successfully complete all the exercises, but not without a few puzzling missteps. Customizing the ArcMap Interface The initial steps in this project were to create a simple demonstration version of ArcMap to help non-gis professionals interact with a map of the United States. All tool menus except Main Menu, Draw, Standard, and Tools were removed from the map document and available tools in the Standard and Tools menus were reduced. The tools menu (Figure 1) contains only the Zoom In, Zoom Out, Pan, Select Features, Identify, Measure, and Label tools. I left it undocked within the map display area. Figure 1 - Modified "Tools" Menu from Customized ArcMap document. Screen capture from ArcMap 9.3 (ESRI 2008) After simplifying the menu interface, a startup procedure was written using the Visual Basic Editor. Upon opening the ArcMap document the user is asked to provide their name in an input box (Figure 2), which is saved as a string and concatenated with a welcome message in a greeting message box (Figure 3). Figure 2 What s your name? Input Box from ArcMap document. Screen capture from ArcMap 9.3 (ESRI 2008) Figure 3 Hello Message Box from ArcMap document. Screen capture from ArcMap 9.3 (ESRI 2008) When the user clicks OK the message box closes and the user can begin to explore the map (Figure 4). I centered the map on the continental United States. If the display location were to be in Alaska or Hawaii I d recenter to include those areas. Additional features that would enhance usability of the application would be to include a menu with options to zoom to a particular state or city. JCourson_Project1 Page 1

2 Figure 4 Lesson1 ArcMap document. Screen capture from ArcMap 9.3 (ESRI 2008) As other class members noted in the Lesson 1 forum, I experienced problems getting the document to save my customizations. It took a few tries before I realized that every time I opened the document the default file for saving customizations reverted to Normal.mxt. After deleting and reconfiguring my Normal.mxt the third time I decided to save a copy of it with another name so I could more easily recapture my preferred customized settings. I also learned that by renaming my mxd file after completing my customizations, I lost them again since they were saved to the original file name. Web Page I have created a Web Page at It contains brief biographical information, contact information and a single blog entry. I ve included links to sites for several organizations I relate to as well as a link to where some of the maps and datasets I ve developed are available. Programming Exercises The most challenging section for me related to the Illustrating the Concepts code below: Dim pmap As IMap Set pmap = pmxdoc.focusmap Dim pflayer As IFeatureLayer2 Set pflayer = pmap.layer(0) Dim strdisplayfield As String strdisplayfield = pflayer.displayfield MsgBox strdisplayfield, vbokonly, "Test" JCourson_Project1 Page 2

3 Even though I successfully used parts of it to complete the Set the map document s RelativePaths property exercise and I understand that the first two lines point to the map document, the next two lines point to the focus frame, the next two lines point to the top layer in the table of contents, and the last three lines extract and deliver a display value to the message box if you took the code away and asked me to recreate it I d be absolutely lost. I think that s the greatest concern for me right now. I m trying to study the code strings and understand line by line what each element means, but sometimes even when I can figure out how to make it work, I m still unsure exactly how and why it works. I am finding that as I go back and rework the same exercises, with each repetition the concepts become clearer. That gives me hope. The first three practice exercises where fairly simple. I accomplished them on either one try or found that it was essentially a typo somewhere in my code that caused it not to work right the first time. I appreciated having the codes and explanations to refer to and only looked at those after I managed to get the code working. The fourth practice exercise proved more challenging as it pointed me back to the Illustrating the Concepts section I mentioned above. I wasn t initally sure whether I was looking within the document, the focus frame or a layer to find the value. After several failed efforts I looked at the Practice 4 Solution code. After reviewing the code, it made sense, but if that help hadn t been available I might still be searching for a solution. The first exercise for credit was very straightforward. I got it right on one try. The second was more challenging and it took three tries before I got a working solution. All the struggle over the SearchTolerancePixels property in practice exercise 4 paid off when I began to look for the RelativePaths property. The problem I encountered here was the syntax for setting the value to True. Once I found the right syntax I discovered again how reassuring the autocomplete feature can be as it presented me with a True/False values to choose. I added a message box (Figure 5) that delivered a visual confirmation that the value had been set to True. As a rule I keep this set as default for all new files. In this case I left it as a sub procedure but it seems like it would be advisable to add this kind of property setting to the OpenDocument procedure for Normal.mxt. Figure 5 RelativePath Value Message Box. Screen capture from ArcMap 9.3 (ESRI 2008) I ve included an Appendix with the VBA code from all of the exercises. I ve heard from experienced programmers that it is helpful to store copies of your code so that you can refer back to things that work as you re learning how to write more complicated code. Sources ESRI (2008). ArcMap 9.3. Redlands, CA: Environmental Systems Research Institute, The Pennsylvania State University ( ) GEOG 485: GIS Programming and Customization, Lesson 1: Basics of ArcGIS Customization. The Pennsylvania State University World Campus Certificate/MGIS Programs in GIS. Retrieved September 30, 2009 from This document is published in fulfillment of an assignment by a student enrolled in an educational offering of The Pennsylvania State University. The student, named above, retains all rights to the document and responsibility for its accuracy and originality. JCourson_Project1 Page 3

4 Appendix Project 1 VBA Code Private Function MxDocument_OpenDocument() As Boolean Dim strusername As String strusername = InputBox("Please enter your name:", "What's your name?", "your name here") MsgBox "Hi, " & strusername & "! This is the Penn State World Campus GIS Demonstration Project. Please explore this exciting map of the United States!", vbokonly, "Hello" End Function Public Sub Test() Dim pmap As IMap Set pmap = pmxdoc.focusmap Dim pflayer As IFeatureLayer2 Set pflayer = pmap.layer(0) Dim strdisplayfield As String strdisplayfield = pflayer.displayfield MsgBox strdisplayfield, vbokonly, "Test" Public Sub Practice1() Dim strx As String strx = "Hello" MsgBox strx, vbokonly, "Practice 1" Public Sub Practice2() Dim x As Integer Dim y As Integer Dim z As Integer x = 9 y = 7 z = x + y MsgBox z, vbokonly, "Practice2" Public Sub Practice3() Dim strusername As String strusername = InputBox("Pleae enter your name", "User Name Entry", "enter your name here") MsgBox "Hi " & strusername & "!", vbokonly, "Welcome!" Public Sub Practice4() Dim stp As Long stp = pmxdoc.searchtolerancepixels MsgBox stp, vbokonly, "Search Tolerance Pixels" JCourson_Project1 Page 4

5 Public Sub Exercise1() Dim dblusernum As Double dblusernum = InputBox("Enter a number", "Enter a Number to calculate its square", "enter number here") Dim dblsquare As Double dblsquare = dblusernum * dblusernum MsgBox "That number squared is: " & dblsquare, vbokonly, "Your number squared!" Public Sub Exercise2() pmxdoc.relativepaths = True Dim strrelpath As String strrelpath = pmxdoc.relativepaths MsgBox "In this map document, the store relative path names to data sources property is set to: " & strrelpath, vbokonly, "RelativePath Value" JCourson_Project1 Page 5