How to program Visual Basic 5.0: control creation edition

294 Pages·1997·1.22 MB·English

by  Jeffrey P. McManus

How to Program
Visual Basic 5.0

Control Creation Edition
by Jeffrey P. McManus
CONTENTS
Introduction
l How to Hurt Uncooperative Users
l Creating Controls in Visual Basic is So Great I Could Just Explode
l Why Johnny Can't Create Controls
l This Is Not What This Book Is About
l Who Should Use This Book
Chapter 1 What's New In Visual Basic 5.0
l What's New in the Integrated Development Environment
m Projects, Files, and the Project Explorer
m Form Layout Window
m Indent/Outdent
m Customizable Toolbars
m Wizards
m Procedure View/Full Module View
m Bookmarks
m Automatic Code Completion
m Drag-and-Drop Editing
l New Language Features
m Assertions
m Enumerated Constants
m AddressOf
m Language Features Pertaining to Control Creation
l Summary
Chapter 2 Control Basics
l Is an ActiveX Control?
m Differences between OCX Controls and ActiveX Controls
m Contexts in Which You Can Use ActiveX Controls
l Your Control's Interface
m Properties
m Events
m Methods
l Summary
Chapter 3 Developing Your First Control
l Getting Started
m Setting Up the IDE
l Managing the Project
l Designing Your Control
l Testing the Control
l Exposing the HappyHour Control's Caption Property
m Coding the Property Get
m Coding the Property Let
m Testing the New Caption Property
m Resizing the Control
m Supplying a Default Caption Using the Extender Object
m Storing Design-Time Property Changes
l Exposing Properties Using the ActiveX Control Interface Wizard
m Testing the New Code
l Summary
Chapter 4 Control Properties
l Creating Property Procedures
m Using the Example Files on the CD-ROM
m Declaring Properties
m Using Property Let and Property Get
m Enumerated Properties
m Validating Property Procedures
m Using the PropertyBag Object
m Properties of Constituent Controls
m Properties Your Control Should Provide
m Creating a Procedure Description
m Designating a Property as the Default
m Grouping Properties
m Synchronizing a Property with Properties of Its Container
l Creating Custom Property Pages
m Using the Property Page Wizard
m Programming the PropertyPage Object
m Modifying the Property Page
l Summary
Chapter 5 Handling and Raising Events
l Creating Custom Events
m Understanding the Syntax of Event and RaiseEvent
m Creating an Event
m Creating an Event That Includes a Parameter
m Raising Events of Constituent Controls
m Providing Standard Events
m Specifying a Default Event
m Understanding Container-Provided Events
l Events of the UserControl Object
l Summary
Chapter 6 Control Methods
l Creating a Method
m What the WatchClock Method Does
m Testing the WatchClock Method
l Creating a Method That Takes an Argument
m Testing the Parameterized Event Procedure
l Creating a Method That Returns a Value
m Testing the CalculateHowLong Method
l Implementing Standard Methods
l Using Methods Supplied by the Container
l Summary
Chapter 7 Interacting With the Container
l What Is a Container?
m Visual Basic Containers
m Interacting with Non-VB Containers
m Using Microsoft Internet Explorer as a Container
l Using the Extender Object
m Properties Exposed by the Visual Basic Extender Object
m Providing an Enabled Property
m Using the AmbientProperties Object to Synchronize Properties
m Using Extender Properties with the Containerator Project
m The Container Property
l Summary
Chapter 8 Using Constituent Controls
l Inherent Controls
l Acting on All the Constituent Controls in Your Control
l Third-Party Controls
m Licensing Considerations Applicable to Third-Party Controls
l Locating Commercial Controls
m Microsoft
m CNET ActiveX.com
m TechWeb ActiveXpress
m Dave Central
m BrowserWatch ActiveX Arena
m Catalog Resellers Specializing in VB Controls and Add-Ons
l Summary
Chapter 9 User-Drawn Controls
l Graphics Methods
m Addressing the Coordinate System
m The Line Method
m The Circle Method
m The PSet Method
m The Print Method
m The Cls Method
l The Paint Event
l Example of a User-Drawn Control: The Hexagon Control
l The Refresh Method
l Displaying Your Control As Disabled
l Displaying the Default Property
l Showing That Your Control Has the Focus
l Summary
Chapter 10 Window Dressing
l Giving Your Control a Transparent Background
l Design Time, Runtime, Read-Only Properties
m Demonstration
l Permitting Your Control to Act as a Container
m Demonstration
l Implementing Access Keys
m Access Keys with Constituent Controls
m Using the AccessKey Property and AccessKeyPress Event
l Controls That Are Invisible at Runtime
m Demonstration
l Controls That Align to the Edges of Forms
m Demonstration
l Adding an About Box
l Project Templates
m Demonstration
m Changing the Default Templates Folder
l Adding a Toolbox Bitmap
m Demonstration
l Summary
Chapter 11 Making Windows API and DLL Calls
l Declaring DLL Calls
l Sample Project: The SoundButton Control
m Using Resources
m Creating a Resource Script
m Compiling Your Resource File
m Beyond Clicksnd
l Sample Project: The MenuPic Control
m Designing the MenuPic Control
m How ChangeMenu Works
m Implementing MenuPic's Properties
m Calling ChangeMenu
m Testing MenuPic
l Summary
Chapter 12 Distributing Your Control
l Compiling Your Control
m Demonstration
m Confirming That It Worked
l Binary Compatibility
l Naming Your Control
l Project Properties
m Version Number
m Version Information
m Checking Version Information
m Application
m DLL Base Address
l Testing Your Compiled Control in Microsoft Access
l Using the Setup Wizard
l Binary Licensing
m When to License
l Localization
l Registering and Unregistering Controls
l Using Regclean
m A Word of Caution about Regclean
l Summary
Chapter 13 Deploying Your Control on the Web
l Hosting a Web Site
l For the Net-Impaired
l Obtaining the ActiveX Control Pad
l Crash Course on HTML and VBScript
m About HTML
m About VBScript
l Using the ActiveX Control Pad
l Testing Your Control in a Web Browser
m Adding VBScript Code to the Web Page
m Extra Credit
l Making It Work with Netscape
l Using the Setup Wizard in an Internet Context
l CAB Files and CODEBASE Tags
m Using the CODEBASE Tag
m GUIDs
l Safety Considerations
m Script-safe
m Initialization-Safe
l Licensing Issues on the Web
m Using the Lpk_tool Utility
l Signing Your Code
m Obtaining a Software Publisher's Certificate
l Using Signcode to Sign Your.CAB File
m Testing the Signed .CAB File
l Summary
Chapter 14 Controls That Interact with the Internet
l Asynchronous Download of Property Values
m Using the AsyncRead Method
m The HappyHour Control's URL Properties
m What the Timer Event Does
m Testing the Code
l Internet Controls as Constituent Controls
m Obtaining the Mabry Mail Control
m Building the TechSupport Control
l Adding Web-Browsing Features to Your Control
m Using Internet Explorer as a Constituent Control
m Controls That Act as Hyperlinks
m Using the Internet Explorer Automation Object
l Summary
Chapter 15 Debugging and Error Trapping
l Debugging
m The Immediate Window
m Breakpoints
m Using Option Explicit
m The Locals Window
m Monitoring Expressions Using Watches
m Using Assertions
l Error-Handling
m Writing Error-Handlers
m The Err Object
m Raising Errors
l Summary
Chapter 16 Object-Oriented Programming
l Object-Oriented Concepts
l Classes
m Creating a Class
l Collections
m How Collections Work
m Creating a Collection Class
m Performance Considerations
l Incorporating a Class in a Control
l Building Interfaces Using the Implements Keyword
l Using Friend Methods
l Summary
Chapter 17 Database Access
l Visual Basic Data Access
m Using a Microsoft Access Database
m Other Data Sources Accessible to the Data Control
m More Choices: Using Open Database Connectivity
m Data-Aware Controls in Visual Basic
m How Database Access Works
l Providing Data Awareness in Your ActiveX Control
l Summary
Appendix Regular Expressions in Perl
l The Rules of Regular Expression Matching
m Unquantified Atoms
m Quantifiers and Quantified Atoms
m Assertions
l Examples of Regular Expressions
l Operators That Use Regular Expressions in Perl
m Perl's Regular Expression Matching Operator: m//
m Perl's Search-and-Replace Operator: s///
Chapter 19 Glossary
Credits
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Publisher Stacy Hiquet
Associate Publisher Stephen Sayre
Acquisitions Editor Simon Hayes
Development Editor Angela Allen
Copy Editor Candace Crane
Technical Reviewer Vidya Bharat and John Kee
Production Editors Barbara Dahl and Edith Rex
Proofreader Jeff Barash
Cover Illustration and Design Megan Gandt
Illustrator Mina Reimer
Book Design and Layout Bruce Lundquist
Indexer Anne Leach
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ISBN: 1-56276-485-3
Acknowledgments
I'd like to thank Laura Lemay for her advice and support. Thanks to John Chen for his friendship and for his extremely valuable
assistance in helping me navigate the sometimes Byzantine machinations of a certain software company over the years. And thanks
to Mike and Laura Medina for their help and advice.
Thanks to my editors at Ziff-Davis Press for believing in me and for letting me keep the corny jokes in.
I'd also like to thank the following legion of truly righteous mental heavyweights for their technical help and hints: Tom Digby, Jim
Huguley, Matt Luallen, Tales Normando, Marty Pavlovic, and Bob Rossney. Your generosity with your time and knowledge has
improved this book greatly.
This book was written in San Francisco and Livermore, California in Fall of 1996 and Winter of 1997.
This is not a sexist cookbook.
Introduction
A world in which every piece of software has the ability to interact with every other piece of software ain't gonna happen anytime
soon. But you can always dream. I personally hope to someday put a software chip in a small house pet-a cat, perhaps-and control it
through the use of Visual Basic properties and methods.
But perhaps I'm sharing too much.
Windows developers have had the ability to use software components ever since Visual Basic first came out. People Who Know
About These Things tell us that the Windows component market-formerly restricted to VB developers, now expanding to
accommodate developers in applications as disparate as FoxPro, Access, Visual C++ and Microsoft Word 97-has grown to a sizable
software subindustry that sells on the order of $250 million worth of products. That's a lot of widgets, whatzits, and data-aware ding-
dongs by anybody's standards.
How to Hurt Uncooperative Users
With the advent of this kooky Internet thing, it's certain that this component technology will continue to grow and mature and
eventually get to the point where it will become a part of every application, Web page, vibrating hotel bed, and house pet on earth.
However, it's not there yet. The idea of sending software components to users through a Web page is a compelling one-if your users
are using a Web browser that supports the software component technology standard you chose.
Of course, if visitors to your Web site simply refuse to use "The Correct Browser," you have a number of options for remediation
that you may wish to consider:
l Shoot them
l Garrote them
l Systematically buff their elbows with sandpaper until they howl with agony
l etc.
Only through the cooperation of Webmasters all over the world will the ActiveX assimilation of Planet Earth be completed in a
timely and cruelty-free fashion.
Until Web browser support for ActiveX becomes as ubiquitous as the rubber insole, there are still plenty of reasons to develop
ActiveX controls. You probably have at least a few of these in mind, or you wouldn't have bought this book (and I wouldn't have
written it). It is my opinion that rapid development of ActiveX controls will be most prevalent in two areas: vertical applications
(written in Visual Basic or any one of a number of other development environments that support ActiveX) and on private Web
servers (also known as intranets).
It will be interesting to see what happens with ActiveX support in Microsoft Office 97, although I couldn't tell you exactly how it's
going to work, because as I write this, Office 97 is exactly 24 hours away from being released. (I, for one, am quivering with
anticipation.)
Creating Controls in Visual Basic is So Great I Could Just Explode
One of the great unsung promises of ActiveX is that-unlike other cross-platform component technologies, such as Java-you can
theoretically build an ActiveX component in any programming language and use it with any programming language.
No longer do VB programmers need to rely on the third-party control market for controls written in C++. In fact, the advent of VB as
a control-development environment means that a Visual Basic developer can now turn the tables, providing ActiveX components for
developers who create applications in Visual C++. What a concept.
It's likely that more languages and development environments will support the creation of ActiveX controls as time goes by. In fact,
as this book was being written, a beta version of a new tool for creating ActiveX controls called VisualX from InterGroup
Technologies was released. It's not quite as good as Visual Basic's Control Creation Edition (for reasons I'll let you discover on your
own), but it is worth checking out. You can download it for free from http://www.intergrouptech.com/form.html.
Why Johnny Can't Create Controls
Visual Basic programmers have been whining for years about their inability to create ActiveX controls in Visual Basic. "How hard
could it be to include this ability in VB?" they ask. Well, the Visual Basic gnomes at Microsoft listened. And they came up with a
bonus: In addition to giving you a way to create ActiveX controls in Visual Basic, they made it a free download from the Microsoft
Web site.
Because it's so easy to create controls using Visual Basic (easy, that is, once you've purchased and read the informative tome you
now hold in your hands), it's likely that we'll begin to see a number of new, interesting, fascinating, and perhaps disgusting
contributions to the world of ActiveX controls in coming years.
So, there it is. You have before you the Visual Basic Control Creation Edition. Please use its powers only for good, never for evil.
This Is Not What This Book Is About
Now that you have an idea about what this book is about, I'll go into some of the things it isn't about. (By the way, I always hate it
when authors say "er, um, this topic is beyond the scope of this book." It seems like such a cop-out. So when a topic is beyond the
scope of this book, I try to give you a reference to a book where the topic is covered in more depth.)
This book does not delve into the technology initiatives behind ActiveX controls such as COM, DCOM, and OLE, except where they
are necessary to convey points directly related to building controls in Visual Basic. I did this by design; you don't need to be steeped
in these initiatives in order to create good controls any more than you need to know everything about the Windows API to create
good Visual Basic applications. If you want information on the forest rather than the trees, I'll refer to you the documentation and
tools available in the ActiveX Software Development Kit, downloadable from http://www.microsoft.com/activex.
You'll also notice that I conspicuously avoid referring to Java in this book. This isn't because I don't have anything to say about
ActiveX versus Java; it's more a function of the fact that I didn't want to muddle the instructional material in this book with pointless
factoids on this alleged clash of the technology titans. My opinion on the whole ActiveX versus Java hubbub, for what it's worth, is
this: Viewing ActiveX and Java as a winner-take-all competition for domination of the Internet is like viewing lowfat milk versus
skimmed milk as a competition for domination of your refrigerator.
To get your very own copy of Visual Basic 5.0 Control Creation Edition for free, go to the Microsoft site at http://www.microsoft.
com/vbasic/controls/.
Who Should Use This Book
This book is designed for intermediate to advanced Visual Basic programmers who are interested in creating ActiveX controls in
Visual Basic. You may be interested in creating controls that will reside in Web pages, or you may want to create controls that will
reside in compiled Visual Basic applications. Either way, this book addresses all of the steps you'll need to take to create a control in
VB.
Although this book uses the Control Creation Edition for its examples, you can use any version of Visual Basic 5.0 to create controls.
The concepts are the same from one edition of Visual Basic to the next.
You should be aware that this book is not a comprehensive reference to programming in VB. It would, however, serve as an
excellent companion to a more general book on VB. If you're a beginner and you want to learn how to create ActiveX controls, it
might behoove you to learn how VB works in general before jumping into control creation. You'll save yourself some time and some
grief.
Finally, enjoy the book. And don't forget to check out the Web page at http://www.well.com/user/jeffreyp/activex/. I'll try to keep it
updated with as much control-creation information and links to VB resources as I have time for.