Developer's Guide, Delphi 7 for WindowsBorland Software Corporation 100 Enterprise Way, Scotts Valley, CA 95066-3249 www.borland.com
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Delphi™ 7 for Windows™
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HDE1370WW21001 7E5R0802 0203040506-9 8 7 6 5 4 3 2 1 D3
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Chapter 1 Introduction 1-1 What’s in this manual? . . . . . . . . . . . . . . 1-1 Manual conventions . . . . . . . . . . . . . . . . 1-2 Developer support services . . . . . . . . . . . . 1-3
Part I Programming with Delphi
Chapter 2 Developing applications with Delphi 2-1 Integrated development environment . . . . . . 2-1 Designing applications . . . . . . . . . . . . . . 2-2 Creating projects . . . . . . . . . . . . . . . . . . 2-3 Editing code . . . . . . . . . . . . . . . . . . . . 2-4 Compiling applications . . . . . . . . . . . . . . 2-4 Debugging applications . . . . . . . . . . . . . . 2-5 Deploying applications . . . . . . . . . . . . . . 2-5
Chapter 3 Using the component library 3-1 Understanding the component library . . . . . 3-1
Properties, methods, and events . . . . . . . 3-3 Properties . . . . . . . . . . . . . . . . . . 3-3 Methods . . . . . . . . . . . . . . . . . . 3-4 Events . . . . . . . . . . . . . . . . . . . . 3-4 User events . . . . . . . . . . . . . . . . . 3-4 System events . . . . . . . . . . . . . . . 3-4 Internal events . . . . . . . . . . . . . . . 3-4
Objects, components, and controls . . . . . . . . 3-5 TObject branch . . . . . . . . . . . . . . . . . 3-6 TPersistent branch . . . . . . . . . . . . . . . 3-7 TComponent branch . . . . . . . . . . . . . . 3-7 TControl branch . . . . . . . . . . . . . . . . 3-9 TWinControl/TWidgetControl branch . . .3-10
Chapter 4 Using the object model 4-1 What is an object? . . . . . . . . . . . . . . . . . 4-1
Examining a Delphi object . . . . . . . . . . 4-2 Changing the name of a component . . . . . 4-4
Inheriting data and code from an object. . . . . 4-5 Scope and qualifiers . . . . . . . . . . . . . . . . 4-5
Private, protected, public, and published declarations . . . . . . . . . . . . . . . . . . 4-6
Using object variables . . . . . . . . . . . . . . 4-7 Creating, instantiating, and destroying
objects . . . . . . . . . . . . . . . . . . . . . . 4-8 Components and ownership . . . . . . . . . 4-9
Defining new classes . . . . . . . . . . . . . . . 4-9 Using interfaces . . . . . . . . . . . . . . . . . . 4-12
Using interfaces across the hierarchy . . . . 4-13 Using interfaces with procedures . . . . . . 4-14 Implementing IInterface . . . . . . . . . . . 4-14 TInterfacedObject . . . . . . . . . . . . . . . 4-15 Using the as operator with interfaces . . . . 4-16 Reusing code and delegation. . . . . . . . . 4-16
Using implements for delegation . . . . 4-17 Aggregation . . . . . . . . . . . . . . . . 4-18
Memory management of interface objects. . . . . . . . . . . . . . . . . . . . . 4-18
Using reference counting . . . . . . . . 4-19 Not using reference counting . . . . . . 4-20
Using interfaces in distributed applications . . . . . . . . . . . . . . . . . 4-21
Chapter 5 Using BaseCLX 5-1 Using streams . . . . . . . . . . . . . . . . . . . 5-2
Using streams to read or write data . . . . . 5-2 Stream methods for reading
and writing . . . . . . . . . . . . . . . 5-2 Reading and writing components . . . 5-3 Reading and writing strings . . . . . . . 5-3
Copying data from one stream to another. . . . . . . . . . . . . . . . . . . 5-4
Specifying the stream position and size. . . 5-4 Seeking to a specific position . . . . . . 5-4 Using Position and Size properties . . . 5-5
Working with files . . . . . . . . . . . . . . . . 5-5 Approaches to file I/O . . . . . . . . . . . . 5-6 Using file streams . . . . . . . . . . . . . . . 5-6
Creating and opening files using file streams . . . . . . . . . . . . . . . 5-7
Using the file handle . . . . . . . . . . . 5-8 Manipulating files . . . . . . . . . . . . . . . 5-8
Deleting a file . . . . . . . . . . . . . . . 5-8 Finding a file . . . . . . . . . . . . . . . 5-8 Renaming a file . . . . . . . . . . . . . . 5-10 File date-time routines . . . . . . . . . . 5-10 Copying a file . . . . . . . . . . . . . . . 5-11
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Using TIniFile and TMemIniFile . . . . 5-12 Using TRegistryIniFile . . . . . . . . . 5-13 Using TRegistry . . . . . . . . . . . . . 5-13
Working with lists . . . . . . . . . . . . . . . . 5-14 Common list operations . . . . . . . . . . . 5-15
Adding list items . . . . . . . . . . . . 5-15 Deleting list items . . . . . . . . . . . . 5-15 Accessing list items . . . . . . . . . . . 5-16 Rearranging list items . . . . . . . . . . 5-16
Persistent lists. . . . . . . . . . . . . . . . . 5-16 Working with string lists . . . . . . . . . . . . 5-17
Loading and saving string lists . . . . . . . 5-17 Creating a new string list . . . . . . . . . . 5-18
Short-term string lists . . . . . . . . . . 5-18 Long-term string lists . . . . . . . . . . 5-18
Manipulating strings in a list . . . . . . . . 5-20 Counting the strings in a list . . . . . . 5-20 Accessing a particular string . . . . . . 5-20 Locating items in a string list . . . . . . 5-20 Iterating through strings in a list . . . . 5-20 Adding a string to a list . . . . . . . . . 5-21 Moving a string within a list . . . . . . 5-21 Deleting a string from a list . . . . . . . 5-21 Associating objects with a
string list . . . . . . . . . . . . . . . . 5-22 Working with strings . . . . . . . . . . . . . . 5-22
Wide character routines . . . . . . . . . . . 5-22 Commonly used long string routines . . . 5-23 Commonly used routines for
null-terminated strings. . . . . . . . . . . 5-26 Declaring and initializing strings . . . . . . 5-27 Mixing and converting string types . . . . 5-28 String to PChar conversions. . . . . . . . . 5-28
String dependencies . . . . . . . . . . . 5-29 Returning a PChar local variable . . . 5-29 Passing a local variable as
a PChar . . . . . . . . . . . . . . . . . 5-29 Compiler directives for strings . . . . . . . 5-30
Creating drawing spaces . . . . . . . . . . . . 5-31 Printing . . . . . . . . . . . . . . . . . . . . . . 5-32 Converting measurements . . . . . . . . . . . 5-33
Performing conversions . . . . . . . . . . . 5-33 Performing simple conversions . . . . 5-33 Performing complex conversions . . . 5-33
Adding new measurement types . . . . . . 5-34
Creating a simple conversion family and adding units. . . . . . . . . . . . . . . 5-34
Declare variables . . . . . . . . . . . . . 5-35 Register the conversion family . . . . . 5-35 Register measurement units . . . . . . . 5-35 Use the new units . . . . . . . . . . . . . 5-35
Using a conversion function . . . . . . . . . 5-36 Declare variables . . . . . . . . . . . . . 5-36 Register the conversion family . . . . . 5-36 Register the base unit . . . . . . . . . . 5-36 Write methods to convert to and
from the base unit . . . . . . . . . . . . 5-36 Register the other units . . . . . . . . . 5-37 Use the new units . . . . . . . . . . . . . 5-37
Using a class to manage conversions . . . . 5-37 Creating the conversion class . . . . . . 5-38 Declare variables . . . . . . . . . . . . . 5-39 Register the conversion family and
the other units . . . . . . . . . . . . . . 5-39 Use the new units . . . . . . . . . . . . . 5-40
Defining custom variants . . . . . . . . . . . . 5-40 Storing a custom variant type’s data . . . . 5-41 Creating a class to enable the
custom variant type . . . . . . . . . . . . . 5-42 Enabling casting . . . . . . . . . . . . . 5-42 Implementing binary operations . . . . 5-44 Implementing comparison
operations . . . . . . . . . . . . . . . . 5-46 Implementing unary operations . . . . 5-47
Copying and clearing custom variants . . . 5-48 Loading and saving custom
variant values . . . . . . . . . . . . . . 5-49 Using the TCustomVariantType
descendant . . . . . . . . . . . . . . . . 5-50 Writing utilities to work with a
custom variant type . . . . . . . . . . . . . 5-50 Supporting properties and methods
in custom variants . . . . . . . . . . . . . . 5-51 Using TInvokeableVariantType . . . . . 5-51 Using TPublishableVariantType . . . . 5-53
Chapter 6 Working with components 6-1 Setting component properties . . . . . . . . . . 6-2
Setting properties at design time . . . . . . 6-2 Using property editors . . . . . . . . . . 6-3
Setting properties at runtime. . . . . . . . . 6-3 Calling methods. . . . . . . . . . . . . . . . . . 6-3
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Working with events and event handlers . . . . 6-3 Generating a new event handler . . . . . . . 6-4 Generating a handler for a
component’s default event . . . . . . . . . 6-4 Locating event handlers . . . . . . . . . . . . 6-4 Associating an event with an existing
event handler . . . . . . . . . . . . . . . . . 6-5 Using the Sender parameter . . . . . . . 6-5 Displaying and coding shared
events . . . . . . . . . . . . . . . . . . . 6-5 Associating menu events with
event handlers . . . . . . . . . . . . . . . . 6-6 Deleting event handlers . . . . . . . . . . . . 6-6
Cross-platform and non-cross-platform components . . . . . . . . . . . . . . . . . . . . 6-7
Adding custom components to the Component palette . . . . . . . . . . . . . . 6-9
Chapter 7 Working with controls 7-1 Implementing drag and drop in controls . . . . 7-1
Starting a drag operation . . . . . . . . . . . 7-1 Accepting dragged items . . . . . . . . . . . 7-2 Dropping items . . . . . . . . . . . . . . . . . 7-3 Ending a drag operation. . . . . . . . . . . . 7-3 Customizing drag and drop with
a drag object. . . . . . . . . . . . . . . . . . 7-3 Changing the drag mouse pointer . . . . . . 7-4
Implementing drag and dock in controls . . . . 7-4 Making a windowed control a
docking site . . . . . . . . . . . . . . . . . . 7-4 Making a control a dockable child . . . . . . 7-5 Controlling how child controls
are docked . . . . . . . . . . . . . . . . . . . 7-5 Controlling how child controls
are undocked . . . . . . . . . . . . . . . . . 7-6 Controlling how child controls respond
to drag-and-dock operations . . . . . . . . 7-6 Working with text in controls. . . . . . . . . . . 7-6
Setting text alignment . . . . . . . . . . . . . 7-7 Adding scroll bars at runtime. . . . . . . . . 7-7 Adding the clipboard object. . . . . . . . . . 7-8 Selecting text . . . . . . . . . . . . . . . . . . 7-9 Selecting all text . . . . . . . . . . . . . . . . 7-9 Cutting, copying, and pasting text . . . . . 7-10 Deleting selected text . . . . . . . . . . . . 7-10 Disabling menu items . . . . . . . . . . . . 7-11 Providing a pop-up menu . . . . . . . . . . 7-11 Handling the OnPopup event. . . . . . . . 7-12
Adding graphics to controls . . . . . . . . . . . 7-13 Indicating that a control is
owner-drawn. . . . . . . . . . . . . . . . . 7-13 Adding graphical objects to
a string list . . . . . . . . . . . . . . . . . . 7-14 Adding images to an application . . . . 7-14 Adding images to a string list . . . . . . 7-14 Drawing owner-drawn items . . . . . . 7-15
Sizing owner-draw items . . . . . . . . . . . 7-16 Drawing owner-draw items . . . . . . . . . 7-17
Chapter 8 Building applications, components, and libraries 8-1
Creating applications . . . . . . . . . . . . . . . 8-1 GUI applications. . . . . . . . . . . . . . . . 8-2
User interface models . .…