<< Click to Display Table of Contents >> Navigation:  How To Use the VPE Control > VPE VCL > Understanding the Data Types and Declarations (Delphi)

Because the properties and methods of the VPE Control (for .NET, Java, PHP, Python, Ruby, ActiveX and Delphi / C++ Builder VCL) are nearly 100% the same, we explain the API of the VPE control for all the different programming languages within this single book. We use a meta-description to describe the data types, properties, methods and parameters of the VPE API.

Here is how the meta-description is converted to Delphi:

Throughout this manual, methods and parameters are always declared in the form <Data Type> <Name>, e.g. boolean AutoDelete would be declared in Delphi as AutoDelete: Boolean.

The data type in square-brackets defines the data type for the VCL Component.

 

Example:

property PenStyle [integer] PenStyle

means that this property is of type "integer".
The leading "PenStyle" type declaration is for the .NET control only.

 

Data Types:

VpeCoord is Double

boolean is Boolean

integer is Integer

pointer is Pointer

long is Long

string is String

Color is TColor (in fact a 32-bit integer)

 

Properties / Methods:

The keyword method declares a method, e.g. method void CloseProgressBar().

A method is either a Procedure or a Function, depending on how the return type of the method is declared. The keyword immediately following the word method declares the method.

void is a Procedure which does not return a value, e.g.
method void StorePos() is in Delphi: procedure StorePos()

all other declarations declare a function, e.g.
method boolean WriteDoc(string FileName) is in Delphi
function WriteDoc(FileName: String) : Boolean

The keyword property describes a property. The line below the declaration of the property explains, how the property can be accessed (read-only, write-only or read / write together) and if it can be accessed during runtime only, or also during design time.

 

Example:

property boolean PageScrollerTracking

read / write; design- & runtime

means: the property is of type Boolean, its name is PageScrollerTracking and it can be accessed for read (you can read its value, e.g. n := PageScrollerTracking) and for write (you can assign it a value, e.g. PageScrollerTracking := True) and it is available during runtime (while your application is running) and design time (when you are developing your forms).

It would be declared in Delphi as PageScrollerTracking: Boolean