Essential Delphi 2.0 Fast : How to Develop Applications in Delphi 2.0

193 Pages·1996·8.681 MB·English

by  John Cowell BSc(Hons), MPhil, PhD (auth.)

Essential Delphi 2.0 Fast
How to Develop Applications in Delphi 2.0
Springer
London
Berlin
Heidelburg
New York
Barcelona
Budapest
Hong Kong
Milan
Paris
Santa Clara
Singapore
Tokyo
John Cowell
Essential
Delphi 2.0 Fast
How to Develop
Applications in Delphi 2.0
With 216 Figures
, Springer
John Cowell, BSc(Hons), MPhll, PhD
Department of Computer and Information Sciences
De Montfort University
Kents Hill Campus, Hammerwood Gate, Kents Hill
Milton Keynes, MK7 6HP, UK
ISBN-13: 978-3-540-76026-9 e-ISBN-13: 978-1-4471-1490-1
DOl: 10.1007/978-1-4471-1490-1
British Library Cataloguing in Publication Data
Cowell, John R.
Essential Delphi 2.0 fast: how to develop applications in Delphi
1. Delphi (Computer program language)2. Programming (mectronic computers)
I.Title
005.2'62
ISBN-13: 978-3-540-76026-9
Library of Congress Cataloging-in-Publication Data
Cowell, John, 1957-
Essential Delphi 2.0 fast: how to develop applications in Delphi I John Cowell
p. cm.
Includes index.
ISBN-13: 978-3-540-76026-9
1. Delphi (Computer file) 2. Computer software-development.
I. Title.
QA76.76.D47C69 1996
005.265-dc20 96-33758
Apart from any fair dealing for the purposes of research or private study, or criticism or
review, as permitted under the Copyright, Designs and Patents Act 1998, this publication may
only be reproduced, stored or transmitted, in any form or by any means, with the prior
permission in writing of the publishers, or in the case or reprographic reproduction in
accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries
concerning reproduction outside those terms should be sent to the publishers.
© Springer-Verlag London Limited 1996
Microsoft, MS, Visual Basic, Windows are trademarks of Microsoft Corporation
Delphi is a trademark of Borland Corporation
The use of registered names, trademarks etc. in this publication does not imply, even in the
absence of a specific statement, that such names are exempt from the relevant laws and
regulations and therefore free for general use.
The publishers makes no representation, express or implied, with regard to the accuracy of the
information contained in this book and cannot accept any legal responsibility or liability for
any errors or omissions that may be made.
Typeset from disk by T & A Typesetting Services, Rochdale
3413830-543210 Printed on acid-free paper
Contents
1 WHY USE DELPHIl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Is This Book For You? ............................ 2
How to Use This Book. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
What Computer You Need to Run Delphi. . . . . . . . . . . . . . 3
What's New in Delphi 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
New Versions. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 4
Speed. .. . . . . . . . ....... . . . . . .. .. ... .. . . . . . . ... . 4
Converting from Delphi! to Delphi 2. . . . . . . . . . . . . . . . . . 5
The Visual Component Library. . . . . . . . . . . . . . . . . . . . . . 5
Language and Compiler Changes. . . . . . . . . . . . . . . . . . . . . 6
Menu Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
The Object Respository. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Database Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 RWNING DELPHI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Starting Delphi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
The Delphi Programming Environment . . . . . . . . . . . . . . . .. 11
The Form ..................................... 11
The Component Palette. . . . . . . . . . . . . . . . . . . . . . . . . .. 12
The Object Inspector. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13
The Code Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 14
The SpeedBar .................................. 15
3 THE DISAPPEARING MEMO • • • • • • • • • • • • • • • • • • • • • •• 16
Introduction ..................................... 16
Event Driven Software .............................. 16
Creating the User Interface .......................... 17
Finding Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18
Changing Component Properties. . . . . . . . . . . . . . . . . . . . .. 19
Running the Program .............................. 21
Writing the Pascal Code ............................ 21
4 HOW PROJECTS ARE ORGANISED •••••••••••••••••• 23
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
File Types in Delphi Project . . . . . . . . . . . . . . . . . . . . . . . . . 23
y
vi Contents
Design-time Project Files. . . . . . . . . . . . . . . . . . . . . . . . . .. 23
Compiler Generated Files. . . . . . . . . . . . . . . . . . . . . . . . . .. 24
Project Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 24
Unit Source Files and Graphical Form Files. . . . . . . . .. . . .. 24
Files You Need to Edit. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 24
The Project Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 25
The SpeedBar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 25
The Program Manager SpeedMenu . . . . . . . . . . . . . . . . . . .. 26
The Project Options Dialog. . . . . . . . . . . . . . . . . . . . . . . . .. 26
The Forms Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26
The Application Options. . . . . . . . . . . . . . . . . . . . . . . . .. 27
The Compiler Options. . . . . . . . . . . . . . . . . . . . . . . . . . .. 28
The Linker Options. . . . . . . . . . . . . . . . . . . . . . . . . . .... .. 29
The Directories/Conditional Options . . . . . . . . . . . . . . . .. 30
5 THE STANDARD COMPONENT PALETTE •••••••••••• 31
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31
The TLabel Component . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31
The TEdit Component . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32
The TMemo Component. . . . . . . . . . . . . . . . . . . . . . . . . . .. 32
The TButton Component . . . . . . . . . . . . . . . . . . . . . . . . . .. 33
The TCheckBox Component. . . . . . . . . . . . . . . . . . . . . . . .. 33
The TRadioButton Component. . . . . . . . . . . . . . . . . . . . . .. 33
The TListBox Component. . . . . . . . . . . . . . . . . . . . . . . . . .. 34
The TComboBox Component. . . . . . . . . . . . . . . . . . . . . . .. 34
The TScrollBar Component. . . . . . . . . . . . . . . . . . . . . . . . .. 35
The TGroupBox Component. . . . . . . . . . . . . . . . . . . . . . . .. 35
The TRadioGroup Component . . . . . . . . . . . . . . . . . . . . . .. 35
Using the Components. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 36
6 COMPUTER BUYERS SURVEY ••••••••••••••••••••• 37
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 37
The Completed Form. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 37
Using the Grid to Align Components. . . . . . . . . . . . . . . . .. 38
Creating the Form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 38
Entering List and Combo Box Data. . . . . . . . . . . . . . . . . . .. 39
Run-time Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 41
Aligning Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 41
Unit Changes .................................... 44
7 DIALOG BOXES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45
The ShowMessage Procedure . . . . . . . . . . . . . . . . . . . . . . .. 45
The MessageDlg Function. . . . . . . . . . . . . . . . . . . . . . . . . .. 46
Contents vii
Return Values from MessageDlg . . . . . . . . . . . . . . . . . . . . . . 48
Creating Input Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Custom Dialog Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8 USING FORMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Modal and Modeless Forms. . . . . . . . . . . . . . . . . . . . . . . . .. 50
Form Templates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Allowing Forms to Use Each Other .................... 53
Password Input Dialog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Finding Forms and Units . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Saving Forms as Templates. . . . . . . . . . . . . . . . . . . . . . . . . . 56
Custom Dialog Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
The OpenFile Dialog Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
9 MDI FORMS .................................... 61
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
The FormStyle Property ............................ 61
Creating Parent and Child Forms ...................... 62
Auto-Creation of Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Displaying Child Forms ............................. 64
Tiling Child Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
10 MENUS ........................................ 66
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
The Menu Designer ................................ 66
Designing Main Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
The Caption and Name Properties. . . . . . . . . . . . . . . . . . . . . 67
Adding, Inserting and Deleting Menu Items. . . . . . . . . . . . . . 68
Separator Bars, Accelerator and Short-cut Keys ........... 68
Creating Sub Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Designing Pop-up Menus ........................... 70
The Menu Designer Speed Menu. . . . . . . . . . . . . . . . . . . . . . 70
Using Menu Templates ............................. 71
Creating Menu Templates ........................... 72
Connecting Menu Events and Code. . . . . . . . . . . . . . . . . . . . 73
The Font Dialog Box ............................... 75
The TColorDialog Component. . . . . . . . . . . . . . . . . . . . . . . . 76
11 DEBUGGING.................................... 78
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 78
Run-time and Logic Errors . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Using the Debugger ............................... 79
viii Contents
Stopping Program Execution . . . . . . . . . . . . . . . . . . . . . . .. 81
Setting Breakpoints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 81
Restarting After Breakpoints. . . . . . . . . . . . . . . . . . . . . . . .. 82
Viewing Breakpoints . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. 82
Using Breakpoints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 83
Disabling, Enabling and Deleting Breakpoints . . . . . . . . . . .. 83
Conditional Breakpoints. . . . . . . . . . . . . . . . . . . . . . . . . . .. 84
Stepping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 85
Pausing Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 85
Using the SpeedBar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 86
Viewing Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 86
Modifying Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 87
Using the Debugger ............................ ~ .. 88
12 GRAPHICS..................................... 89
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 89
Creating Graphics .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 89
The Graphics Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 89
Adding Graphics at Design-time. . . . . . . . . . . . . . . . . . . . .. 90
Using the Image Editor. . . . . . . . . . . . . . . . . . . . . . . . . .. 91
Adding Graphics at Run-time. . . . . . . . . . . . . . . . . . . . . . .. 92
The Pen Property. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 93
Drawing Lines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 93
Drawing Shapes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 94
The Brush Property . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 95
The Pixel Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 96
Creating a Drawing Application . . . . . . . . . . . . . . . . . . . . .. 97
SpeedButton Properties . . . . . . . . . . . . . . . . . . . . . . . . . . .. 98
Writing the Event Handlers. . . . . . . . . . . . . . . . . . . . . . . .. 98
Rubber Banding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Using the ColorDialog ............................. 101
Using the Clipboard ............................... 103
13 MOUSE AND KEYBOARD EVENTS. • • • • • • • • • • • • • • • • • 104
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
The Mouse Events ................................ 104
The Scribble Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
OnMouseDown and OnMouseUp Events ................ 105
The Keyboard Events .............................. 106
Using the OnKeyUp and OnKeyDown Events ............ 108
14 USING DATABASES •••••••••••••••••••••••••••••• 109
Introduction ...•..................•............. 109
What is a Database? . . . . . . . . . . . . . • . . . • . . . . . . . . . . . . . 109
What Databases Can Delphi Use ........... 110
0 •••••••••••
Contents ix
The Database Forms Expert ......................... 110
Running the Browser ............................. 113
Using Data Controls ................. '.' ........... 114
The DataField Property. . . . . . . . . . . . . . . . . . . . . . . . . . .. 115
The DataSource Property. .......................... 115
The TDataSource Component ....................... 116
The TTable Component. ........................... 116
The TQuery Component . . . . . . . . . . . . . . . . . . . . . . . . . .. 117
Creating a Database Application . . . . . . . . . . . . . . . . . . . .. 120
15 DELPHI COMPONENTS REFERENCE. • • • • • • • • • • • • • •• 122
Introduction ......................... '-' . . . . . . . .. 122
The Standard Page ............................... 122
The Additional Page .............................. 126
The Data Access Page. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 132
The Win 3.1 Page. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 130
The Data Access Page. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 132
The Data Controls Page. . . . . . . . . . . . . . . . . . . . . . . . . . .. 133
The Dialogs Page ................................ 134
The Systems Page ................................ 140
The OCX Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 144
The Samples Page. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 145
The WIN 95 Page. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 147
16 PASCAL PRIMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 152
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 152
Program Structure ............................... 152
Program Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 152
Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 153
Operators ...................................... 154
Bitwise operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 155
Declaring Variables ............................... 157
Declaring Constants . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 157
Converting Between Types .......................... 158
Calling Procedures and Functions .................... 159
Passing Parameters ............................... 160
Using Functions ................................. 161
Controlling Program Flow .......................... 162
If Then Else Statements .......................... 162
Case Statements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 163
Repeat Statements .............................. 164
While Statements ............................... 164
For Statements ................................ 165
Defining Data Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 165
x Contents
Enumerated Types .............................. 166
Subrange Types ................................ 167
Arrays ..................................•.... 168
Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
17 OBJECT PASCAL • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •• 171
Introduction .................................... 171
What are Objects? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
The TForm Object. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Object Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
Private and Public ................................ 174
Using the Is Operator .............................. 175
Object Orientation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
18 DELPHI AND VISUAL BASIC. • • • • • • • • • • • • • • • • • • •• 176
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
The Development Environment. . . . . . . . . . . . . . . . . . . . . . . 176
Compilers and Interpreters. . . . . . . . . . . . . . . . . . . . . . . . . . 177
Declaring Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Type Checking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
Using Strings .................................... 178
High-Level File Commands .......................... 178
Database Access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Which is Better? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
INDEX ........................................... 181