Mastering AutoCAD VBA

575 Drawing an AutoCAD Line from Word... Combining the power of AutoCAD and Visual Basic providesendless opportunities for creating impressive customized applications ranging fromstreaml

Mastering ™

San Francisco • Paris • Düsseldorf • Soest • London

Marion Cottingham

AutoCAD VBA

Mastering ™

San Francisco • Paris • Düsseldorf • Soest • London

Marion Cottingham

Acquisitions and Developmental Editor: Raquel Baker

Editor: Carol Henry

Production Editor: Nathan Whiteside

Technical Editor: Steve Hansen

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Copyright © 2001 SYBEX Inc., 1151 Marina Village Parkway, Alameda, CA 94501 World rights reserved The author created reusable code in this publication expressly for reuse by readers Sybex grants readers limited permission to reuse the code found in this publication or its accompanying CD-ROM so long as author is attributed in any application containing the reusabe code and the code itself is never distributed, posted online by electronic transmission, sold, or commercially exploited as a stand-alone product Aside from this specific exception concerning reusable code, no part of this publication may be stored in a retrieval system, transmitted, or reproduced in any way, including but not limited to photocopy, photo- graph, magnetic, or other record, without the prior agreement and written permission of the publisher.

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To all my students, past and present, who have inspired me more than they’ll ever know.

—Marion Cottingham

I would like to thank all my supporters from the University of Western Australia,especially those from the Computer Science and Software Engineering department Inparticular, thanks to Dr Sandra Penrose for her helpful advice; Professor Barry Brady(Executive Dean of the Faculty of Engineering and Mathematical Sciences) for allow-ing me study leave to engage in the scholarly activity of writing this book; ProfessorAlan Robson (Deputy Vice-Chancellor) for his indirect support; and Colin Campbell-Fraser (Director of Public Affairs) for his encouragement

Thanks goes to everyone at Sybex who worked on this book, especially to theAssociate Publisher Cheryl Applewood for giving me the opportunity to write it, andDevelopment Editor Raquel Baker who kept me on track until the book went into itsproduction phase Thanks go to Production Editor Nathan Whiteside, who helped me

to keep to deadlines with his insatiable appetite for chapters He coordinated thewhole project and made the book happen on time

Thanks to the Editor Carol Henry for her excellent editing, enthusiasm, and gestions…from start to finish She truly made this a better read and kept me companyduring the twilight hours while I worked sixteen hours ahead of her hanging upsidedown at the other side of the world Thanks to the Technical Editor Steve Hansen forhis comments and expert advice that also have made this a better book

sug-Thanks to Manufacturing Specialist Steve Melville and to Electronic PublishingSpecialist Jill Niles, who put my words onto the printed page, and to Indexer Ted Laux,who has made all the material in the book easy to find

Finally, thanks to Autodesk for producing AutoCAD, which is such a powerfulsoftware package that is fun to use and has made defunct the phrase “and now back tothe drawing board!”

Contents at a Glance

Introduction xxiii

Part 1 • VBA Macros and the Visual Basic Editor 1

Chapter 1 • Developing a Simple VBA Application 3

Chapter 2 • Creating VBA Macros 29

Chapter 3 • Quick Tour of the IDE 53

Chapter 4 • VBA Programming Concepts 79

Part 2 • Drawing Lines and Solid Areas Using VBA Macros 129

Chapter 5 • The AutoCAD Object Model 131

Chapter 6 • Macro-izing Line Drawing 167

Chapter 7 • Macro-izing Solid Areas 221

Part 3 • Reusability and Customization 267

Chapter 8 • Templates and Reusability 269

Chapter 9 • Creating Drawings with Text 305

Chapter 10 • Debugging Your Code 355

Chapter 11 • Dimensioning Drawings from Your Own Menus and Toolbars 375

Chapter 12 • File Input and Output 419

Part 4 • 2D Drawing Techniques 447

Chapter 13 • Working with 2D Drawing Techniques 449

Chapter 14 • Grouping Objects 471

Part 5 • 3D Drawing Techniques 511

Chapter 15 • Creating and Drawing 3D Solids 513

Chapter 16 • ActiveX Controls 565

Chapter 17 • AutoCAD and the Internet 597

Appendix A • Object Models 619

Appendix B • ASCII Character Set 631

Index 637

CONTENTS AT A GLANCE xiii

Introduction xxiii

Part 1 • VBA Macros and the Visual Basic Editor 1

Chapter 1 • Developing a Simple VBA Application 3

Advantages of Using VBA with AutoCAD 5

The AutoCAD VBA Environment 6

Creating UserForm Modules 7

Puttering around in the Toolbox 8

Developing Your First Application 14

Creating the GUI 14

Setting Captions in the Properties Window 17

The VBA Code Window 19

Running Your Application 24

Saving Your Application 25

Returning to AutoCAD 26

Summary 27

Chapter 2 • Creating VBA Macros 29

What Is a Macro? 31

ThisDrawing Object 31

Standard Modules 32

Creating a Macro to Add Text to a Drawing 34

Using the IDE’s Editing Features to Enter Code 34

Saving a Macro 41

Running a Macro 42

Using VBA’s Date and Time Functions 45

Updating Your DrawText Macro 45

Loading VBA Project Files 46

Loading a Project Manually 46

Loading a Project Each Time a Drawing Object Is Opened 48

Loading a Project When AutoCAD Starts Up 48

Canceling the Loading of a Project at Startup 50

Starting an Application from a Macro 50

Summary 51

Chapter 3 • Quick Tour of the IDE 53

VBA IDE Components 55

Exploring the Menu Bar 56

Setting Your IDE Options 58

The IDE’s Toolbars 62

Printing UserForms 70

Overview of the Code Commands 71

Commands for Editing Code 71

Commands for Debugging Code 72

Commands for Running Code 73

Getting Help 74

Context-Sensitive Help 77

Summary 77

Chapter 4 • VBA Programming Concepts 79

How Code Instructs the Computer 81

Statements and Expressions 81

All about Variables 82

Declaring Variables Using the Dim Statement 84

To Declare or Not to Declare? 85

Handling Arrays of Variables 86

Creating an Array 87

Accessing Array Elements 87

All About Constants 89

Declaring Symbolic Constants 89

Viewing Built-in Constants in the Object Browser 90

Scope of Constants and Variables 94

Public vs Private 94

Scope at the Procedure Level 95

UserForm and Module-Level Scope 95

Static Statements and the Static Keyword 96

Defining Your Own Types 99

Using Conditions to Control Code Execution 100

If…Then…Block 100

If…Then…Else… 102

Select Case Statement 103

Using Loops to Repeat Code 104

Repeating Code a Set Number of Times 105

Repeating Code an Unknown Number of Times 106

Overview of Objects, Properties, Methods, and Events 107

All about Objects 107

AutoCAD Drawing Objects 109

The Microsoft Forms Object Model 111

All about Properties 113

All about Methods 119

All about Events 120

Comparing VBA Programming Constructs 121

Macros 121

Procedures 122

Setting the Tab Order for Controls 125

Functions 126

Parameters and Arguments 127

Programs 127

Applications 128

Summary 128

Part 2 • Drawing Lines and Solid Areas Using VBA Macros 129

Chapter 5 • The AutoCAD Object Model 131

AutoCAD Application Object 133

AutoCAD Document Objects 134

Coding the Finding Name Application 136

Running an Application from a Macro 140

Loading Your Application 142

Communicating with Message Boxes 142

The MsgBox Function 142

Graphical Object Spaces 147

ModelSpace Collection 147

PaperSpace Collection 147

Block Objects 150

Adding Graphical Objects 150

Accessing Graphical Objects 152

Preferences Object 154

Sending Text to the AutoCAD Command Line 159

VB’s String-Handling Functions 161

Summary 166

Chapter 6 • Macro-izing Line Drawing 167

Drawing a Line 169

A Control’s TabIndex and TabStop Properties 176

The With Statement 176

Setting Linetypes 177

Running Your Line Drawing Application 186

Highlighting a Line from a Macro 188

Highlighting and Coloring All Lines 192

Identifying Lines Selected by the User 198

Scales and Weights for Lines 200

Scaling Using a Transformation Matrix 206

Scaling a Line with Respect to the Origin 207

Scaling with Respect to a Fixed Point 210

Multiple Parallel Lines 214

Using Arc Objects 215

Lots of Arcs 217

Summary 219

Chapter 7 • Macro-izing Solid Areas 221

Drawing Circles 223

Drawing Filled Circles 225

Circle of Bricks Application 229

Drawing Freeform Shapes 236

Calculating Areas of Shapes 249

Filling with Inner and Outer Loops 250

Working with Input Boxes 258

Multiple-Line Prompts 259

Drawing a Range Top from a Macro 260

Summary 265

Part 3 • Reusability and Customization 267

Chapter 8 • Templates and Reusability 269

Templates for Reusability 271

Setting the Drawing Units 272

Setting Drawing Units from VBA Code 273

All about Grids 278

Displaying Grid Points 278

Setting Grid Limits 280

Displaying the Whole Grid 281

Setting the Spacing for Grid Points 283

All about Snapping 285

Setting the Snap Spacing 285

Changing All the Environment Settings from a Macro 287

Creating the Floor Plan from a Macro 288

Creating a Template 292

Creating a New Drawing from a Template 293

Macros vs Templates 295

Working with a User Coordinate System 295

Creating a UCS from a Macro 296

Viewing the UCS Matrix 297

Toggling the USC Icon On and Off 300

Copying Objects Using a Macro 302

Summary 304

Chapter 9 • Creating Drawings with Text 305

Creating New Drawing Documents from a Macro 307

Creating Arrays of Objects 310

Polar Arrays 310

Rectangular Arrays 316

Setting Text Attributes 320

Setting Text Attributes in AutoCAD 320

Setting Text Attributes from a Macro 322

Formatting Text from a Macro 324

Formatting Numbers, Times, and Dates 340

Formatting Numbers 340

Formatting Times and Dates 341

Validating Input 342

Adding Text to Arrows 343

Summary 353

Chapter 10 • Debugging Your Code 355

Types of Errors 357

Logic Errors 357

Compiler Errors 359

Run-Time Errors 361

Debug Menu Commands 362

Using Breakpoints 363

Stepping Through Code 365

Using the IDE’s Debugging Windows 366

The Immediate Window 366

The Watches Window 368

The Locals Window 369

Which Debugging Aid to Use? 372

The Call Stack 372

Summary 374

Chapter 11 • Dimensioning Drawings from Your Own Menus and Toolbars 375

AutoCAD’s Dimensioning Styles 377

Dimensioning Drawings from an Application 379

The Aligned Dimensioning Style 380

The Angular Dimensioning Style 381

The Diametric Dimensioning Style 382

The Ordinate Dimensioning Style 383

The Radial Dimensioning Style 384

The Rotated Dimensioning Style 386

The 3 Point Angular Dimensioning Style 386

A Dimensioning Application 387

Saving Your Dimension Styles 400

Using Your Own Dimension Style 403

Customizing Menu Commands 405

Creating a New Menu to Run Macros 406

Creating Your Own Toolbar 411

Adding Preprogrammed Toolbar Buttons 416

Summary 418

Chapter 12 • File Input and Output 419

Handling Drawing Files in Your Code 421

Creating a New Drawing from a Macro 421

Saving a Drawing to a File 425

Verifying That a File Exists 427

Copying Files 429

Displaying Open and Save As Dialog Boxes 430

Using the CommonDialog Control 432

Writing Data to a File from Code 437

Input and Output Modes for Opening Files 441

The Application Path Property 442

Using the Input Statement to Read Data from a File 443

Closing Files 445

Summary 446

Part 4 • 2D Drawing Techniques 447

Chapter 13 • Working with 2D Drawing Techniques 449

Interactive Drawing Techniques for Precision 451

Changing Grid and Snap Angles 451

Controlling Polar Tracking 453

Drawing Splines 456

Adding and Loading Shapes 461

Loading and Adding Shapes from a Macro 462

Moving a Drawing Object from within Code 465

Summary 469

Chapter 14 • Grouping Objects 471

Collecting Objects into Layers 473

Creating Layers from the AutoCAD Window 473

Creating Layers from a Macro 474

Changing Settings in the Layer Properties Manager 483

The On, Freeze, and Lock Options 485

Locking and Unlocking Layers in Code 485

Freezing and Thawing Layers in Code 486

Turning Layers On and Off in Code 488

Accessing All Layers from a Macro 488

Grouping Objects into Blocks 490

Creating a Simple Block 490

Adding a Block to a Drawing 492

Referencing External Blocks 494

Moving Blocks 496

Using Selection Sets 496

Selection Modes 504

InitializeUserInput Method 504

Using Groups 505

Creating a New Group 505

Accessing Individual Drawing Objects from a Group 509

Summary 509

Part 5 • 3D Drawing Techniques 511

Chapter 15 • Creating and Drawing 3D Solids 513

Creating 3D Solids 515

Creating a Box 521

Creating a Wedge 524

Creating a Sphere 526

Creating a Torus 529

Creating a Cone 532

Creating a Cylinder 535

Constructing Complex Solids 543

Determining Whether Two Solids Intersect 547

Grow Your Own Solids 547

Creating Solids by Extrusion 547

Creating Solids by Revolution 551

Chamfered and Filleted Edges 554

Chamfering and Filleting Edges from a Macro 554

Cross-Sectioning 3D Solids 560

Summary 564

Chapter 16 • ActiveX Controls 565

ActiveX and COM 567

Using AutoCAD with Other Applications 567

Dragging Objects into AutoCAD 567

Using ActiveX Controls in Macros 569

Exchange between AutoCAD and Excel 569

Saving Line Data to an Excel Spreadsheet 570

Drawing an AutoCAD Line from Excel 573

Exchange between AutoCAD and Word 575

Sending Data to Word from an AutoCAD Macro 575

Drawing an AutoCAD Line from Word 578

Exchange between AutoCAD and a Database 580Saving Line Data in a Database 583Creating an Access Module from a VBA Macro 588Displaying Data in Access Forms 591Summary 596

Chapter 17 • AutoCAD and the Internet 597

URL Paths of Files on the Web 599Browsing the Web for Files 599Downloading a Web File Using Macros 600Getting the URL Using a Macro 601Launching the Browser from a Macro 603The Code for Getting a Web File 605The Code for Sending a File to the Web 606Putting It All Together 608Preparing Drawings for Publishing on the Web 609Adding Hyperlinks to a Drawing 614Adding Hyperlinks from the AutoCAD Window 615Adding Hyperlinks from a Macro 616Summary 618

Appendix A • Object Models 619

AutoCAD Object Model 621Microsoft Office Object Model 624Microsoft Excel Object Model 626Microsoft Access Object Model 628Microsoft Word Object Model 629

Appendix B • ASCII Character Set 631

Index 637

Autodesk first included Microsoft’s Visual Basic for Applications (VBA) inAutoCAD Release 14 Combining the power of AutoCAD and Visual Basic providesendless opportunities for creating impressive customized applications ranging fromstreamlining the routine tasks you currently perform using AutoCAD to creatingdrawings in seconds that would normally take hours The book takes you step-by-stepthrough how to create macros to automate the routine tasks you currently do inAutoCAD It shows you how to create powerful Windows applications so that you canrun your macros at the click of a button You’ll quickly learn how much fun it is tobuild graphical user interfaces (GUIs) by simply dragging and dropping controls from

a toolbox to a UserForm—you already do much the same thing when you developdrawings using AutoCAD

The material in this book is compatible with AutoCAD 14, AutoCAD 2000, andAutoCAD 2000i

I’m sure you’ll enjoy developing code with all the pop-up help provided by theVisual Basic for Applications Integrated Development Environment (VBA IDE) Ifyou’re lucky enough to be using AutoCAD 2000i with its new updated Heidi® graphicsengine, you have access to its revolutionary Internet/intranet tools that enable you topublish drawings on the Web to speed up your design review process You’ll enjoy theimprovements to the Array interface that help you preview your results, and the exten-sion to the 3D Orbit feature that allows lights, materials, and textures support whileorbiting You’ll also find that you can now ask questions of the Help facility, rather thanhaving to guess at the name of a command, method, or property And you’ll also notice

an Active Assistant on display to provide additional help

If you are not using AutoCAD 2000i and would like more information about it, go

to Autodesk’s AutoCAD Product Center at the following URL Here you can get productinformation, view an interactive demonstration, or (in the United States and Canada)order a free demo CD

http://www3.autodesk.com/adsk/index/0,,303942-123112,00.html

Who Should Read This Book

This book assumes that the reader is already a casual user of AutoCAD and knows itsfundamentals (opening and closing drawing files, interactively creating drawings, and soforth) The material in this book extends this knowledge by showing how to perform the

same tasks from VBA code, and how to enhance AutoCAD by customizing additionalinterfaces that make it easier to perform some tasks.

To the reader who wants to learn how to code macros in VBA, this book assumes

no prior knowledge of VBA or any other programming language It is the ideal bookfor AutoCAD users to learn how to write code to automate routine tasks This bookprovides you with the stepping stones needed to develop your very own macros andapplications that run inside AutoCAD

To the reader who has VBA programming experience from other applications,you’ll learn about the numerous objects and collections that AutoCAD has to offer andthe methods and properties these contain

Since most examples show how to perform a task first from the AutoCAD windowand then from VBA code, readers with no coding experience will quickly see the rela-tionships between how they perform a task in the AutoCAD window and the objectsthey need to use in code to perform the same task The reader with coding experiencewill quickly see the relationships of the objects they use in code, to the drawing objects,options, and settings required for the AutoCAD window

What You Can Do with VBA

Endless numbers of tasks are just waiting to be automated using VBA After you’vetaken the time to develop a macro or an application and have fully tested that it workscorrectly, the code is guaranteed to perform correctly and reliably every time you use

it Just think of the timesaving possibilities of running your code instead of goingthrough the same sequence of actions over and over again Using VBA, many tasks can

be completed with one or two mouse clicks—you can’t beat that Freeing up yourtime on the menial tasks lets you concentrate more on the complex tasks that requireyour artistic abilities

As you make your way through this book and become more experienced at gramming, you’ll get more and more ambitious and find lots of things that are suitablefor automating Just about any task that you do manually in AutoCAD can be auto-mated using VBA This book takes you by the hand and gently guides you deeper intothe “mysteries” of coding Because of the VBA IDE’s easy-to-use features, programmers

pro-no longer need to be gurus You’ll be amazed at just how quickly you start developingfull-blown Windows applications that run smoothly alongside AutoCAD

What’s In This Book

This book takes you through the practical steps of creating powerful and time-savingVBA macros and applications The focus is on automation aimed at saving time,increasing productivity, and producing complex drawings at the click of a button Thebook is divided into five parts:

Part 1: VBA Macros and the Visual Basic Editor

Part 1 shows you how to develop your first application and takes you on a quick tour ofthe Visual Basic Editor You’ll also be introduced to some VBA programming conceptsthat you’ll find useful as a reference as you progress through the book

Chapter 1 provides step-by-step instructions for developing a simple applicationthat requires a GUI, containing controls from the VBA Toolbox that are coded torespond to a user’s actions

Chapter 2 shows you how to create macros that can run on their own or be used tostart an application You’ll learn to make the most of the IDE’s powerful editing features.Chapter 3 takes you on a quick tour of the IDE, showing you how to access its vari-ous windows You’ll also see how to display some of the toolbars, and how to make thebest use of the Help facility

Chapter 4 covers all the programming concepts you need for getting well way as an AutoCAD VBA programmer You’ll find it useful to have all this information

under-in one location rather than dispersed throughout the book—it’s much easier to comeback to later

Part 2: Drawing Lines and Solid Areas Using VBA Macros

Part 2 is your tutor for using objects from the AutoCAD Object Model—lines, circles,and freeform shapes—and how to fill areas with color

Chapter 5 shows the hierarchical structure of the AutoCAD Object Model You’ll seehow to access its objects from code You’ll work through what’s required to communicatewith users via message boxes, and learn how to send a command to the AutoCAD com-mand line from a macro

Chapter 6 covers drawing lines and setting their attributes (linetype, color, andthickness) from a macro You’ll also see how to scale drawing objects from a macro

Chapter 7 demonstrates drawing circles and freeform shapes and filling them withcolor The points defining the freeform shapes are selected by the user, and the values ofthe coordinates are passed to a macro.

Part 3: Reusability and Customization

In Part 3, you’ll fashion an AutoCAD template and create a new drawing documentfrom code You’ll see how to design a new group of menu commands and toolbar but-tons in the AutoCAD window to run your macros, and how to read and write data to afile

Chapter 8 shows how to set the AutoCAD environment settings and make a plate drawing from a macro It compares macros and templates from the point of view

tem-of reusability, and introduces User Coordinate System (UCS) concepts applicable toAutoCAD VBA programming

Chapter 9 describes the process of creating a new drawing document from a macroand how to create polar and rectangular arrays You’ll also see how to display text from

a macro, and how to format numbers, dates, and times

Chapter 10 introduces you to the many debugging features found in the IDE Ittalks about various kinds of errors you may encounter You’ll see how you can watchthe values of variables change as the code is executed

In Chapter 11, you’ll add a new group of menu commands to the AutoCAD windowand create toolbar buttons for quick access to these new commands

Chapter 12 discusses how to transfer data to and from files, and how to add aCommon Dialog control to display the Windows Open and Save As dialog boxes

Part 4: 2D Drawing Techniques

Part 4 discusses interactive drawing techniques using the snap and grid features You’llsee how to group objects and set group attributes

Chapter 13 discusses interactive drawing techniques for increased precision,including grid and snap It tells you how to create and manipulate a spline curve, andhow to animate the movement of a drawing object

Chapter 14 demonstrates the grouping of objects into layers or blocks so that theycan be handled as single entities It shows how to freeze and thaw layers and how tolock and unlock them

INTRODUCTION xxvii

Part 5: 3D Drawing Techniques

Part 5 describes the creation and drawing of 3D solids and how to view them from ferent angles using the 3D Orbit control

dif-In Chapter 15, you’ll create a range of primitive solids and combine them usingunion, intersection, and subtraction operators You’ll also see how to create solids usingextrusion and revolution, how to remove hidden lines, and how render solids with fullcolor—from your VBA macro

In Chapter 16, you’ll explore the exchange of data among other Microsoft tions, using objects from Excel, Access, and Word as examples

applica-Chapter 17 discusses AutoCAD 2000i’s latest Internet features You’ll see how tolaunch your Web browser from code, validate URL addresses, and open and save draw-ings on the Internet You’ll use the Publish to Web Wizard that creates the HTML filesfor your very own Web pages You’ll also see how to add hyperlinks to a drawing

This book also features two bonus chapters (18 and 19) on the CD, which extendyour skills in several areas See “What’s On the CD” later in this Introduction

Appendix B lists all the ASCII symbols in a handy, one-stop reference table foryour convenience

AutoCAD Versions Compatible with This Book

Readers using AutoCAD 14, 2000, 2000i, and even future versions of the program willall benefit from this book It is written to be as universally applicable as possible, sincethe VBA concepts and language hardly change between versions of AutoCAD Eachnew release brings new objects providing additional functionality For the most part,

the new releases are upward-compatible, in that any macros written for one versionwill normally run without problems on a later release So the code in the listingsthroughout this book and on the CD will likely be happy to run without problems forseveral years to come.

The screenshots throughout this book were taken using AutoCAD 2000i

Conventions Used in This Book

This book uses a number of conventions to present information in as readable a format

as possible Tips and Warnings appear from time to time to call attention to specialhighlights

Tips provide extra information that will be helpful in completing the task at hand.

Warnings alert you to situations where particular care must be taken to avoid problems.

This book takes advantage of several font styles and conventions used for the

pro-gramming code Bold font in text indicates something that you type at the keyboard A

monospaced fontis used for code listings and code snippets, for URLs, and for names In code lines, a continuation arrow (↵) indicates that the code line wraps down

file-to the next line due file-to space limitations of the book When a continuation arrow ispresent, you do not have to add a line break if you are typing the code yourself

Have fun unlocking the power of VBA!

What’s On the CD-ROM

The accompanying CD contains all the numbered code listings you’ll find throughoutthis book With the CD, you can quickly access the code without having to enter ityourself from scratch Just transfer the code to the Visual Basic Editor, and then youcan run the macros and try out any changes you wish to make

Also on the CD is Adobe Acrobat Reader, for your convenience in easily accessingthe bonus chapters, which are in PDF format.

Bonus Chapters

The CD also includes two bonus chapters with additional exercises to build your2D and 3D drawing skills

Chapter 18: Once you’ve learned the basics of 2D drawing techniques, you can

build on these skills with the exercises in Chapter 18, which demonstrate how toplot a drawing using the Plot Table Wizard, and how to change a Paper Space view-port from a macro You can also build your VBA skills with the exercise on how tochange a Paper Space viewport from a macro

Chapter 19: Exercises in this chapter build on the 3D drawing skills developed

in Part 5 They cover rendering and lighting effects, including using macros toaccomplish hidden-line removal, shading, and rendering of 3D solids You’ll seehow to control the level of smoothness at which a surface is rendered, and how tochange the lighting—all from macros

Chapter 1

Developing a Simple VBA Application

I n this chapter, you will learn how to create a simple VBA

appli-cation through a series of tutorials You will learn how to employ visual tools to create the graphical user interface, and write code

to execute simple commands You will also explore the basics of the Visual Basic environment by using its features to create practical code that you can reuse for repetitive tasks.

If you consider yourself an intermediate user of AutoCAD VBA and have already written some successful VBA code, you may want to skip this chapter—or even just skim over the entire Part I, depending

on your experience The material covered in Chapter 4,“VBA gramming Concepts,” will always be useful to you as a reference This chapter covers the following topics:

Pro-• Advantages of using VBA with AutoCAD

• The AutoCAD VBA environment

• Developing your first application

Advantages of Using VBA with AutoCAD

Visual Basic for Applications (VBA) is a programming environment created by

Microsoft that is built into applications to automate operations It provides tools thatyou can drag and drop to build a graphical user interface (GUI), and a programminglanguage that you can use to interact with AutoCAD objects Using VBA with Auto-CAD allows you to customize your AutoCAD application in seemingly unlimited ways

In this book, you’ll see how simple it is to automate repetitive tasks With the timesaved, you’ll be free to concentrate on applying your artistic talents and engineeringskills to make your drawings more intricate

Once you start writing VBA code, you’ll quickly realize just how easy it is to accessobjects from the AutoCAD and VBA object libraries You’ll soon be able to call on thepower of these objects while gaining a deeper insight into AutoCAD’s features As youstart to see the benefits that VBA macros and applications can provide, you’ll want tospend your extra time customizing even more tasks Before you know it, you’ll have awhole library of reusable macros and applications at your fingertips!

A macro is a group of code statements, usually not very long or complicated, that is useful in automating

a repetitive task In your work at the computer, most likely you’ve used them already without realizing it.

An application is a program that has been created to perform a specific task This can be something very simple, such as prompting the user for their name and password, or something very substantial and complex such as AutoCAD itself.

Another not-so-obvious advantage of learning AutoCAD VBA is that your skillsare transferable to a growing number of other applications that have VBA capability.These applications include all those in the Microsoft Office family of applications, such

as Access, Word, and Excel, in addition to Microsoft Visual Basic itself and about twohundred other licensees

VBA interfaces with applications by communicating and controlling objectsthrough the application’s object libraries, rather than by having any special connection

to the application’s inner workings All you need to know are the names of the objectsinvolved, and you can access their functionality with VBA code You’ll find the objectnames meaningful and easy to remember, such as ThisDrawing (an object in Auto-CAD), ThisDocument (an object in Word), and ThisWorkbook (an object in Excel) Asyou enter the names of objects in your code, the editing features of VBA’s Integrated

ADVANTAGES OF USING VBA WITH AUTOCAD 5

Development Environment (IDE) offer you drop-down lists of elements particular tothe type of object you’ve entered You’ll see how this works in Chapter 2.

You can use a macro to automate just about anything, but it is probably most tive to start with the tasks you have to do time and time again Why not think about thoseboring, uninspiring jobs you hate doing the most, and start with them! These are probablytasks that are time consuming and error prone, so implementing them in macros or appli-cations will not only increase your productivity but lift your spirits by removing some ofthe tedious tasks that make you yawn just by thinking about them (Such as adding all therequired bits and pieces of information for starting a new drawing; or perhaps you’vefound that you regularly draw the same items over and over again.)

produc-After you’ve successfully developed VBA code that works in the ways you want it

to, it’s guaranteed to perform correctly and reliably each time you run it Now there’s an

incentive to learn VBA! So let’s begin by examining the interface where you will writeyour code—the Visual Basic Editor

The AutoCAD VBA Environment

The Visual Basic Editor is the integrated environment in which you develop all your

VBA code As you can see from Figure 1.1, the IDE has its own graphical user interface.Its windows provide all the tools required for creating, editing, debugging, and runningyour macros and applications With this much functionality, the IDE is almost a stand-alone application, except that it can only be opened from the AutoCAD window anddoes not remain open after AutoCAD has been closed

The term VBA Editor is often used synonymously with the IDE even though the IDE provides more than just editing features.

The VBA IDE can be opened from the AutoCAD window in a variety of ways:

• Type vbaide next to the command prompt in the command line.

• Choose Tools ➜ Macro ➜ Visual Basic Editor

• Use the key-combination (shortcut) Alt+F11

In the examples throughout this book, I’ve used menu commands in instructions.Most commands can also be accessed through a toolbar button or a key-combination, sooccasionally I give an alternative access method as a reminder that there are other ways toinvoke commands The access method you use is up to your personal preference

Figure 1.1 AutoCAD’s VBA environment

Chapter 3 takes you on a guided tour of the IDE and discusses some of its features

in more detail

Creating UserForm Modules

A module is just a container for VBA code, and a UserForm module is a window (or

dia-log box) that can be considered a powerful extension to the AutoCAD GUI You decidewhat controls to place on your UserForm in order to perform the tasks required byyour application You can place labels and text boxes in which users can enter the infor-mation that your program needs in order to run You can use option buttons and checkboxes to give users the chance to select the items they require In fact, just about anycontrol you’ve seen in the applications running under Windows is available for use inthe VBA IDE

Adding a UserForm Module to Your Application

To add a UserForm module to your application:

1 Start AutoCAD and choose Tools ➜ Macro ➜ Visual Basic Editor The VBA

IDE opens

2 Choose Insert ➜ UserForm UserForm1 appears, containing a title bar with a

Close button, as shown in Figure 1.2

Project Explorer window

Standard toolbar Menu bar Title bar

Properties window

Code window

THE AUTOCAD VBA ENVIRONMENT 7

Figure 1.2 A brand-new UserForm

A UserForm is the only module that can be viewed from the IDE in two different ways:

• Graphically, by choosing View ➜ Object to open up the UserForm window(see Figure 1.2)

• With code, by choosing View ➜ Code to open up the Code window as shown here:

Opening the Code window displays the event procedure that will run if the

User-Form is clicked There are many events to choose from, but double-clicking any controlautomatically displays the primary event that you’ll most likely want to respond to.You’ll see how to access the other events later in this chapter, in the section “CodingEvent Procedures.”

Puttering Around in the Toolbox

VBA provides a set of common controls in a Toolbox window (see Figure 1.3) You cansimply drag and drop individual controls onto a UserForm to develop GUI features foryour application

Figure 1.3 Controls in the standard Toolbox

If the Toolbox isn’t on display, select the Toolbox command from the View menu

or click the Toolbox icon (shown in the margin) at the end of the Standard toolbar

Both of these actions will be available for selection only when a UserForm has beenadded to a project and it is being viewed in its graphical form rather than as a Codewindow To view a UserForm graphically, simply choose View ➜ Object

These controls are all available for you to drag and drop onto your UserForm,making AutoCAD VBA a powerful visual programming system that’s extremely effi-cient at quickly developing the GUI for a project—you can virtually design your wholeGUI using only the mouse!

You will recognize most of the controls in the Toolbox because you have alreadyexperienced using them in other applications Following are brief descriptions of whateach control does:

Select Objects The Select Objects control is used to resize and move a control

after it has been drawn on a UserForm If you’ve double-clicked another control toinsert multiple instances of it on the UserForm without returning to the Toolbox,you can click the Select Objects control to stop

Label The Label control displays text that you’ve assigned to its Caption property at

design time or in code A Label control is often used to display information or indicate

to a user what data should be entered into a TextBox control The text displayed by theLabel control is strictly read-only and cannot be changed by the user during run time

TextBox The TextBox control allows users to input textual information during

run time It is common practice to assign the empty string (””) to this control’sText property to initialize it or to clear out any data that’s no longer required

Select Objects TextBox ListBox OptionButton Frame TabStrip ScrollBar

CheckBox ComboBox Label

Image

CommandButton MultiPage SpinButton ToggleButton

THE AUTOCAD VBA ENVIRONMENT 9

ComboBox The ComboBox control combines the functionality of the TextBox

control with that of the ListBox control to provide the user with the option of ing text into the TextBox, or clicking the down-arrow button and selecting an itemfrom a drop-down list When an item is selected from the list, it is automatically dis-played in the text box at the top of the ComboBox You can set the Style property ofthis control in order to restrict the user to selecting an item from the ListBox Thiseliminates the need to test whether the user has entered a valid value

enter-ListBox The enter-ListBox control enables the user to select one or more items from a list.

If there are too many items to be displayed at once, a scroll bar will automaticallyappear Even so, this control generally takes up more space than a ComboBox control,which needs only the same amount of space on the UserForm as a TextBox control

CheckBox The CheckBox control enables the user to “check” (select) zero or

more boxes from a group of CheckBoxes This control is often used to indicatewhether items are true or false, or to answer yes or no to questions CheckBoxes aresimilar in function to OptionButtons, except that they allow more than one item to

be selected at the same time

OptionButton OptionButton controls are used in groups of options to allow

selection of one option from the group When only one group of OptionButtons isrequired, it can be placed directly onto the UserForm When there is more thanone group, Frame controls (described just below) are used to separate groups, toenable one OptionButton per group to be selected You determine the Option-Button that will be the default selection If the user selects another OptionButtonfrom the same group, the old one is automatically deselected

ToggleButton The ToggleButton control toggles between on or off, true or false,

and yes or no When clicked, its appearance changes to match its value; it togglesbetween a raised button appearance (off) to a pushed-in appearance (on) The Pic-ture property of this control allows you to display a selection of options to the user

in a graphical way

Frame The Frame control allows a UserForm to be divided into areas where you

can group other controls, such as OptionButtons and CheckBoxes The Framecontrol and the controls inside it then behave collectively as a single entity Whenyou move the Frame, all the controls inside it move, too; when you disable theFrame, all its controls become disabled Frames are typically used to create groups

of OptionButtons on a UserForm, so that an option from each group can beselected rather than just a single option