Delphi 6 nitty gritty

321 Pages·2002·1.773 MB·english

by  Frank Eller

Addison-Wesley
Nitty Gritty
P R O G R A M M I N G S E R I E S
Delphi 6
Frank Eller
ADDISON-WESLEY
An imprint of Pearson Education
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First published in Great Britain in 2002
© Pearson Education Limited 2002
First published in 2001 as Delphi 6 Nitty Gritty by Addison-Wesley Verlag, Germany.
British Library Cataloguing in Publication Data
A CIP catalogue record for this book can be obtained from the British Library.
Library of Congress Cataloging-in-Publication Data
Eller, Frank.
[Delphi 6 nitty gritty. English]
Delphi 6 / Frank Eller.
p. cm. -- (Addison-Wesley nitty gritty programming series)
Translation of: Delphi 6 nitty gritty.
Includes index.
ISBN 0-201-75882-2 (pbk. : alk. paper)
1. Delphi (Computer file) 2. Computer software--Devlopment. I. Title. II. Series.
QA76.76.D47 E44713 2003
005.265--dc21
2002074571
ISBN 0-201-75882-2
Translated by Transcript Alba Ltd, Oban, Scotland.
Typeset by Pantek Arts Ltd, Maidstone, Kent.
Printed and bound in Great Britain by Biddles Ltd of Guildford and King’s Lynn.
Contents
Preface xi
Acknowledgments xiii
Part I – Start up! 1
1 Before you get started … 3
1.1 What is Delphi? 3
1.2 Delphi is object-oriented 4
1.3 Delphi is event-oriented 5
1.4 Delphi’s development environment 5
1.4.1 Main window 6
1.4.2 Object Inspector 7
1.4.3 Object Treeview 8
1.4.4 Code Editor 8
1.4.5 Code Explorer 8
1.5 Options in Delphi 9
1.5.1 Environment Options 9
1.5.2 Editor Properties 11
1.5.3 Project Options 12
1.6 Programming help 15
1.6.1 Code completion 15
1.6.2 Code parameters 16
1.6.3 Evaluation via tooltips 17
1.6.4 Code templates 17
1.6.5 Class completion 17
1.6.6 Hyperlinks in source code 17
1.6.7 To-Do List 17
1.7 New in Delphi 6 18
1.7.1 Object Inspector 18
1.7.2 Code Editor 19
1.7.3 Object Treeview 19
1.7.4 Subcomponents 20
1.7.5 New components 20
1.8 Choosing a version 21
2 Hello World … ? 23
2.1 Creating the interface 23
2.2 Adding the base functionality 24
2.2.1 Closing the program 24
2.2.2 Configuring the result field 24
2.2.3 Tab sequence 25
2.2.4 Text in the input fields 25
2.3 Adding the main function 25
2.4 Preventing incorrect input 28
Part II – Take that! 31
3 Object Pascal 33
3.1 Basic language components 33
3.1.1 Symbols and separators 33
3.1.2 Reserved words and directives 33
3.1.3 Variables and constants 35
3.1.4 Data types 37
3.1.5 Arrays 38
3.1.6 Sets 42
3.1.7 Records 42
3.1.8 Pointers 44
3.1.9 Objects and classes 46
3.2 Loops 50
3.2.1 The forloop 50
3.2.2 The whileloop 51
3.2.3 The repeatloop 52
3.3 Branches 52
3.3.1 If–then–else branching 52
3.3.2 Case branching 53
3.3.3 Procedures and functions 54
3.3.4 Passing parameters 55
3.3.5 Overloading procedures and functions 56
3.4 Units 57
3.4.1 Structure of a unit 57
3.4.2 Mutual visibility of units 58
3.4.3 Units in Delphi 59
4 Delphi’s base elements 61
4.1 Visual components library 61
4.1.1 Common properties 61
4.1.2 Component Palette Standard page 64
4.1.3 Component Palette Additional page 68
4.1.4 Component Palette Win32 page 73
4.1.5 Component Palette System page 79
4.1.6 Component Palette BDE page 81
4.1.7 Component Palette Data Controls page 84
4.1.8 Component Palette dbExpress page 87
4.1.9 Component Palette Internet page 89
4.1.10 Component Palette FastNet page 92
4.1.11 Component Palette Dialogs page 94
4.1.12 Component Palette Samples page 102
4.2 Base classes of a program 103
4.2.1 TApplicationclass 103
4.2.2 TScreenclass 104
4.2.3 TPrinterclass 106
5 Basic elements of an application 109
5.1 Forms 109
5.1.1 Main form of the application 109
5.1.2 Displaying forms 109
5.1.3 Creating forms at runtime 111
5.1.4 Evaluating form contents 111
5.1.5 Transparent forms 113
5.2 Menus 114
5.2.1 Menu Designer 114
5.2.2 Menu templates 116
5.2.3 Important properties 116
5.3 Toolbars 116
5.3.1 TToolbarproperties 116
5.3.2 TToolbuttonproperties 116
5.3.3 Grouping buttons 116
5.4 Status bar 118
5.4.1 Splitting the status bar 119
5.4.2 Modifying panels at runtime 119
5.4.3 Filling the status bar with text 120
5.5 TActionListcomponent 121
5.5.1 ActionList Editor 121
5.5.2 TActionproperties 122
5.5.3 Defining the functionality of actions 122
5.5.4 Adding images 123
5.6 TImageListcomponent 123
5.6.1 ImageList Editor 124
5.6.2 TImageListproperties 124
5.7 Action Manager 125
5.7.1 Adding actions 126
5.7.2 Using actions 126
5.7.3 Modifying actions 127
5.7.4 Mimicking Office 2000 128
6 Functions and procedures 131
6.1 Dialog and message windows 131
6.1.1 ShowMessage 131
6.1.2 InputBox 132
6.1.3 InputQuery 132
6.1.4 MessageDlg 132
6.1.5 Application.Messageboxand Messagebox 134
6.1.6 SelectDirectory 136
6.2 Arithmetical functions 137
6.3 Files and folders 139
6.4 Type conversions 144
6.5 Date and time 146
6.6 Other functions and procedures 148
Part III – Go ahead! 151
7 Program development techniques 153
7.1 String lists 153
7.1.1 List components 153
7.1.2 TStringListclass 155
7.2 Working with one-line strings 156
7.2.1 String formats in Delphi 156
7.2.2 String functions 157
7.3 Working with multiline text 160
7.3.1 TMemo component 160
7.3.2 TRichEditcomponent 162
7.4 Forms and components 166
7.4.1 Finding components 166
7.4.2 Senderparameter 167
7.4.3 Generating components dynamically 167
7.5 Frames 169
7.5.1 Creating a frame 169
7.5.2 Properties and events 169
7.5.3 Example of a frame 170
7.5.4 Accessing a frame’s components 172
7.6 Checking entries 173
7.6.1 Input field restrictions 173
7.6.2 Predefined input masks 174
7.6.3 Global hotkeys query 176
7.7 Working with files 177
7.7.1 Typed files 177
7.7.2 Non-typed (text) files 178
7.7.3 Streams 179
7.8 Registry 184
7.8.1 Structure of the Registry database 184
7.8.2 TRegistryclass 184
7.9 Threads 186
7.9.1 Synchronizemethod 186
7.9.2 Declaring a thread 187
7.9.3 Initializing a thread 188
7.10 Dynamic link libraries 189
7.10.1 Structure of a dynamic link library in Delphi 189
7.10.2 Integrating a dynamic link library 191
7.11 Linking and embedding objects 194
7.11.1 TOleContainercomponent 194
7.11.2 Using TOleContainer 196
7.12 Dynamic data exchange 201
7.12.1 Dynamic data exchange components 202
7.12.2 Example dynamic data exchange project 203
7.13 Drag and drop 207
7.13.1 Drag and drop events 208
7.13.2 Example project 209
8 Delphi and databases 211
8.1 Back to basics 211
8.1.1 Structure of a database 211
8.1.2 BDE database components 212
8.1.3 ADO components 214
8.1.4 dbExpress components 215
8.1.5 Data module 216
8.2 Creating a database with BDE 216
8.2.1 Planning the database 216
8.2.2 Creating the database 218
8.2.3 Creating the interface 224
8.2.4 Programming the functionality 226
8.3 Master/detail databases 234
8.3.1 Specifying the master database 234
8.3.2 Creating a master database 235
8.3.3 Linking databases 237
8.3.4 Modifying the program interface 238
8.3.5 Extending the functionality 239
8.4 Other BDE functions 241
8.4.1 Splitting a database 241
8.4.2 Defining the start and end 241
8.4.3 Bookmarks 242
8.5 Database interface 242
8.5.1 Structure information 242
8.5.2 Restructuring the database 243
8.5.3 Defining aliases 245
8.6 ADO 246
8.6.1 Example ADO project 246
9 Delphi and the internet 251
9.1 TWebBrowsercomponent 251
9.2 NetMasters components 252
9.2.1 Common properties 252
9.2.2 TNmFTPcomponent 252
9.2.3 TNmNNTPcomponent 254
9.2.4 TNmPop3component 256
9.2.5 TNmSMTPcomponent 258
9.3 Your own browser 259
9.3.1 Program interface 259
9.3.2 Programming the functionality 260
9.4 Creating a cgi counter with Delphi 264
9.4.1 Basic requirements 264
9.4.2 OnActionevent 265
10 Developing components 271
10.1 Back to basics 271
10.2 Conventions 272
10.3 Structure of a component class 273
10.4 Properties 275
10.4.1 Property variables and properties 275
10.4.2 Accessing a property 276
10.4.3 Publishing properties 276
10.4.4 Loading and saving property values 277
10.5 Windows messages 278
10.5.1 Basic principles of messages 278
10.5.2 Defining message-handling routines 279
10.5.3 Declaring your own messages 279
10.6 Events 280
10.6.1 Declaring events 280
10.6.2 Intercepting messages 281
10.6.3 Publishing events 282
10.7 Methods 283
10.7.1 Published methods 283
10.7.2 Constructors and destructors 283
10.8 Property editors 284
10.8.1 Programming a property editor 284
10.8.2 Registering a property editor 286
10.9 Numerical components 286
10.9.1 Framework for the new component 286
10.9.2 Features of the new component 287
10.9.3 Component properties 287
10.9.4 Access methods for IntValue 288
10.9.5 Restricting the input field 290
10.9.6 Finished framework 291
10.9.7 Installing the component 293
11 Error-handling and debugging 295
11.1 Exceptions 295
11.1.1 What is an exception? 295
11.1.2 Protecting source code 295
11.1.3 Exception-handling 298
11.1.4 Silent exceptions 300
11.2 Debugging 300
11.2.1 Breakpoints 301
11.2.2 Evaluating variables 303
11.2.3 Watched expressions 304
11.2.4 CPU window 304
Appendix
A ASCII table 307
B Virtual key codes 309
Index 313
Preface
The idea behind the Nitty Gritty series
When you are programming, you also
usually read a great deal. The fact is that the various programming languages have
reached performance levels that make it almost impossible to get an overview of all the
functions offered by a programming environment. This is why there are so many and
varied reference books that attempt to provide a lot of information in an understand-
able way. Unfortunately, the really good reference books from the reputable publishing
houses are usually weighty tomes that will just clutter up your desk. The slimmer books
are easier to handle but often do not contain the information you are actually looking
for. It is just when you are learning something new that you could really do with a
book that has sections that contain reference material about the programming lan-
guage, and sections that show you how to create functioning programs quickly, and
how to make best use of many of the options available in a programming environment.
The Nitty Gritty series of books is based on this idea. These books are interesting
not only for people who are learning a programming language, because they contain a
lot of basic facts, but also for people who already know how to use other programming
languages and want to extend their knowledge.
This is the next chapter of the Delphi story, which began with Borland and Delphi
5 and continued with Delphi 6. Although the software has become more expensive, the
Personal Edition (previously the Delphi Standard Edition) still has almost all the same
features as Version 5. I am rather disappointed by this. It would have been possible to
increase the price slightly and introduce a few of the new features in return. Sadly, this
didn’t happen.
There isn’t much point in writing a book about the Personal Edition (it really can’t
do a great deal), and there is nowhere near enough space for the features of the
Enterprise Edition (I could write 1000 pages in this format and would still only scratch
the surface), so I have restricted myself mainly to the options offered by the Professional
Edition. In my last book, I mentioned that this version is the very least you should pur-
chase, and I am still convinced of this. It really is a wise investment because Delphi 6
has become even better than I dreamed it could. The critics among you will say that it
took long enough to appear. But you will have a product that is well worth the money
and lives up to its reputation. It is a professional development tool that gives you all the
freedom and possibilities of programming under Windows and (if you also have Kylix)
Linux. I wish you every success and hope that this book will be of some use.