Essential Visual Basic 5.0 Fast : Includes ActiveX Control Development

247 Pages·1997·13.63 MB·English

by  John Cowell BSc (Hons)

Essential Visual Basic 5.0 Fast
Includes ActiveX Control Development
Springer
London
Berlin
Heidelberg
New York
Barcelona
Budapest
Hong Kong
Milan
Paris
Santa Clara
Singapore
Tokyo
John Cowell
Essential Visual
s.o
Basic
Fast
Includes ActiveX
Control Development
With 211 Figures
, Springer
John Cowell, BSc (Hons), MPhil, PhD
Department of Computer and Information Sciences
De Montfort University
Kents Hill Campus, Hammerwood Gate, Kents Hill
Milton Keynes, MK7 6HP, UK
British Library Cataloguing in Publication Data
Cowell, John, 1957-
EssentialVisual Basic 5.0 fast : includes ActiveX Control Development
1.Visual Basic (Computer program language) 2.Visual
programming (Computer science)
I.Title
005.1'33
Library of Congress Cataloging-in-Publication Data
Cowell, John, 1957-
Essential Visual Basic 5.0 fast : includes ActiveX Control
Development 1 John Cowell.
p. cm.
Includes index.
ISBN-I3: 978-3-540-76148-8 e-ISBN-I3: 978-1-4471-0983-9
DOl: 10.1007/978-1-4471-0983-9
1. Application software--development. 2. Microsoft Visual Basic.
I. Title.
QA76.76.A65C69 1997 97-17622
005.26'8--DC21 CIP
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 1988, 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 of repro graphic reproduction in accordance with the
terms oflicences issued by the Copyright Licensing Agency. Enquiries concerning reproduction
outside those terms should be sent to the publishers.
© Springer-Verlag London Limited 1997
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 publisher 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.
Typesetting: Camera ready by author
34/3830-543210 Printed on acid-free paper
Contents
1 WHY USE VISUAL BASIC 57 ...................................................................... 1
Introduction .............................................................................................. 1
Why change to version 5? ........................................................................ 2
Is this book for you? ................................................................................. 2
How this book is organised ...................................................................... 3
New features in version 5 ......................................................................... 4
What computer do you need to run Visual Basic 5? ................................ 5
Versions of Visual Basic 5 ....................................................................... 5
Conventions .............................................................................................. 6
2 THE VISUAL BASIC ENVIRONMENT ......................................................... 7
Introduction .............................................................................................. 7
Starting Visual Basic 5 ............................................................................. 7
The Visual Basic design screen .............................................................. 10
The form ................................................................................................. 11
The Form Layout Window ..................................................................... 12
The Project Explorer window ................................................................. l3
The Properties window ........................................................................... 13
The Visual Basic standard menu bar and toolbar ................................... 14
The toolbox ............................................................................................. 15
3 SHRINKING AND GROWING .................................................................... 17
Introduction ............................................................................................ 17
Outline of the Shrinking and Growing program ..................................... 17
Creating a new project.. .......................................................................... 18
Defining the user interface ..................................................................... 19
Moving and scaling ................................................................................ 20
The Properties window ........................................................................... 20
Changing captions .................................................................................. 21
Displaying a picture ................................................................................ 22
Supported file types ................................................................................ 24
Common problems ................................................................................. 24
Running the program .............................................................................. 25
Event driven software ............................................................................. 26
Making the buttons work ........................................................................ 26
Saving the project ................................................................................... 29
v
vi Contents
4 MANAGING PROJECTS AND FILES ....................................................... 30
Introduction ............................................................................................ 30
Opening and closing projects ................................................................. 30
Application files ..................................................................................... 32
FRM files ............................................................................................... 33
BAS files ................................................................................................ 33
OCX files ............................................................................................... 34
FRX files ................................................................................................ 34
CTL files ................................................................................................ 35
CLS files ................................................................................................. 35
Adding elements to a project.. ................................................................ 35
A common problem. ............................................................................... 36
5 STANDARD CONTROLS .......................................................................... 37
Introduction ............................................................................................ 37
The toolbox appearance ......................................................................... 37
Adding controls to forms ....................................................................... 38
Selecting controls ................................................................................... 38
Cutting and Pasting ................................................................................ 39
Common toolbox controls ...................................................................... 39
The pointer icon ..................................................................................... 41
Common properties ................................................................................ 41
The PictureBox control .......................................................................... 42
The Label control ................................................................................... 43
The TextBox Control ............................................................................. 43
Passwords ............................................................................................... 44
Captions and hot keys ............................................................................ 45
The Frame control .................................................................................. 45
The CommandButton control ................................................................. 45
The CheckBox control ........................................................................... 46
The OptionButtons control ..................................................................... 47
The ComboBox control .......................................................................... 47
The ListBox control ............................................................................... 48
The AddItem method ............................................................................. 49
The Sorted property ................................................................................ 49
The HScrollBar and VScrollBar controls ............................................... 49
The Timer control .................................................................................. 50
The Shape, Line and Image Controls ..................................................... 50
6 BUYING A NEW PC ................................................................................... 52
Introduction ............................................................................................ 52
Design of the form ................................................................................. 52
Adding the TextBox controls ................................................................. 53
Contents vii
Adding the CheckBox controls ............................................................... 53
Adding the OptionButton Controls ......................................................... 54
Adding the ListBox and ComboBox controls ........................................ 54
Running the program .............................................................................. 54
Initialising the ListBox and ComboBox ................................................. 55
TabIndex and TabStop ........................................................................... 56
Forms ...................................................................................................... 56
Controlling form properties .................................................................... 56
Using properties ...................................................................................... 57
Hiding and showing forms ..................................................................... 58
Loading and unloading forms ................................................................. 58
The Show method ................................................................................... 59
The Hide method .................................................................................... 59
MDI forms .............................................................................................. 59
Arranging forms ..................................................................................... 60
7 DISPLAYING TEXT .................................................................................... 62
Introduction ............................................................................................ 62
The MsgBox function ............................................................................. 62
Message box text .................................................................................... 63
MsgBox buttons parameter. .................................................................... 64
Getting button input. ............................................................................... 66
Getting text input from a dialog box ...................................................... 67
Missing optional parameters ................................................................... 67
Controlling fonts and font characteristics ............................................... 68
Using the Print method ........................................................................... 70
Formatting numbers dates and times ...................................................... 70
Number format ....................................................................................... 70
Custom formats ...................................................................................... 72
Date and time format.. ............................................................................ 72
Writing to a printer ................................................................................. 74
The Printer object ................................................................................... 74
The PrintForm method ........................................................................... 74
8 DECLARING AND USING VARIABLES .................................................... 76
Introduction ............................................................................................ 76
Declaring variables ................................................................................. 76
Naming conventions ............................................................................... 77
Static variables ........................................................................................ 77
Variables scope ....................................................................................... 78
Variable types ......................................................................................... 78
The Boolean data type ............................................................................ 79
The Byte data type .................................................................................. 79
viii Contents
The Currency data type .......................................................................... 79
The Date data type ................................................................................. 79
The Decimal data type ............................................................................ 79
The Integer data type .............................................................................. 80
The Long data type ................................................................................. 80
The Object data type .............................................................................. 80
The Single data type ............................................................................... 80
The Double data type ............................................................................. 80
The String data type ............................................................................... 80
The Variant data type ............................................................................. 81
Range of data types ................................................................................ 81
Converting between data types .............................................................. 81
Int and Fix .............................................................................................. 82
Arithmetic operations ............................................................................. 82
The comparison operators ...................................................................... 83
Arrays ..................................................................................................... 83
Declaring arrays ..................................................................................... 83
Changing array dimensions .................................................................... 84
User-defined data types .......................................................................... 84
The Erase statement ............................................................................... 85
9 CONTROLLING PROGRAM FLOW .......................................................... 86
Introduction ............................................................................................ 86
Types of program contro1.. ..................................................................... 86
The ILThen. .. Else statement. ................................................................ 87
Nested Ifs ............................................................................................... 87
The Else If clause ................................................................................... 88
The Select Case structure ....................................................................... 88
The GoTo statement ............................................................................... 89
Looping .................................................................................................. 89
The Do ... While clause ............................................................................ 90
The Do ... Until clause .............................................................................. 90
Exit Do statement ................................................................................... 91
The While ... Wend clause ...................................................................... 91
The For. .. Next construct. ........................................................................ 92
Terminating For loops ............................................................................ 92
Exit For .................................................................................................. 93
10 PROCEDURES AND FUNCTIONS .......................................................... 94
Introduction ............................................................................................ 94
Event procedures .................................................................................... 94
General procedures ................................................................................. 95
The scope of event and general procedures ........................................... 95
Contents IX
Passing arguments .................................................................................. 96
Function procedures ............................................................................... 96
11 DEBUGGING ............................................................................................ 98
Introduction ............................................................................................ 98
What is debugging? ................................................................................ 98
Syntax errors and Quick Info ................................................................. 99
Logic errors .......................................................................................... 100
Using breakpoints ................................................................................. 100
Displaying the value of variables ......................................................... 101
Changing code in break mode .............................................................. 102
Continuing and stopping ....................................................................... 102
Stepping ................................................................................................ 102
Watchpoints .......................................................................................... 103
Conditional Compilation ...................................................................... 104
The Call Stack window ......................................................................... 105
The Debug menu .................................................................................. 105
12 OBJECT ORIENTED PROGRAMMING ................................................. 107
Introduction .......................................................................................... 107
Why use object oriented programming? .............................................. 10 7
What are objects? ................................................................................. 108
Using properties .................................................................................... 109
Using methods ...................................................................................... 109
Creating objects at run-time ................................................................. 110
Arrays of forms .................................................................................... 111
Arrays of control variables ................................................................... 112
User-defined classes ............................................................................. 114
Creating and using Collections ............................................................. 116
13 ACTIVEX CONTROLS ........................................................................... 118
Introduction .......................................................................................... 118
What are custom controls? ................................................................... 118
Creating an ActiveX controL .............................................................. 119
The ActiveX clock ................................................................................ 120
Writing the code ................................................................................... 121
Testing the control ................................................................................ 124
Resizing Controls ................................................................................. 126
Incorporating events in a Control ......................................................... 127
Making an OCX file ............................................................................. 130
Control Groups ..................................................................................... 131
The ActiveX Control Interface Wizard ................................................ l31
x Contents
Running the Control Interface Wizard ................................................. 134
Testing the ActiveX Control ................................................................ 138
14 CREATING AND USING MENUS .......................................................... 141
Introduction......................... .. .......................................... .......... ..... ... ... 141
Creating a menu bar ............................................................................. 141
Amending the menu ............................................................................. 143
Shortcut keys ........................................................................................ 143
The Checked property .......................................................................... 144
Enabling and disabling controls ........................................................... 144
Pop-up Menus ...................................................................................... 145
15 USING CUSTOM CONTROLS .............................................................. 148
Introduction .......................................................................................... 148
The CommonDialog control... .............................................................. 148
Common Controls ................................................................................ 151
The Calendar control ............................................................................ 152
The Grid Control .................................................................................. 152
Uses of the Grid control ....................................................................... 153
Changing the number ofrows and columns ......................................... 153
Changing grid text ................................................................................ 154
Changing size....................................................................................... 155
Selecting cells ....................................................................................... 156
Adding and removing rows .................................................................. 156
Aligning text. ........................................................................................ 157
Scroll bars ............................................................................................. 158
Editing grid cells .................................................................................. 158
16 CREATING AND USING GRAPHiCS .................................................... 159
Introduction .......................................................................................... 159
The graphics controls ........................................................................... 159
The Line control ................................................................................... 160
The Shape ControL ............................................................................... 161
Properties of the Shape control ............................................................ 161
The co-ordinate system ........................................................................ 162
Twips and other units ........................................................................... 163
Using graphics methods ....................................................................... 163
Controlling individual pixels ................................................................ 164
The Line method .................................................................................. 164
Drawing boxes ..................................................................................... 165
The Circle method ................................................................................. 166
Drawing circles and ellipses ................................................................. 166