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ProEssentials v8 Help

Chapter 4: VCL Overview


A VCL implementation requires the use of Borland Delphi or Builder.

 

The ProEssentials VCL files are:

 

File Name

Description

"PEGVCL.PAS"

Graph

"PESGVCL.PAS"

Scientific Graph

"PE3DVCL.PAS"

3D Scientific Graph

"PEPCVCL.PAS"

Pie Chart

"PEPSVCL.PAS"

Polar Smith Rose

"PEGRPAPI.PAS"

Pascal header file to ProEssentials DLL

 

These files are located in the Delphi and Builder sub-directories.

 

If using Builder, there are also some additional files:

 

File Name

Description

"PEGCPP.CPP"

Graph

"PESGCPP.CPP"

Scientific Graph

"PE3DCPP.CPP"

3D Scientific Graph

"PEPCCPP.CPP"

Pie Chart

"PEPSCPP.CPP"

Polar Smith Rose

 

 

Object Model

The VCL interfaces have a simple object model that closely resembles our DLL interface.  Within the property reference material, at the top of each property topic, you'll see a table with various property attributes.  For example, the property FontSize has such an entry.

 

Scope

All ProEssentials Objects.

Type

Int32

Default

PEFS_MEDIUM

.NET

PeFont.FontSize

Ocx|Vcl

FontSize

DLL

PEP_nFONTSIZE

 

If developing with either VCL or OCX interfaces, you'll refer to this property via the OCX|VCL row heading.

 

Ocx|Vcl

FontSize

 

For a control named PEGraph1, to programmatically control the FontSize property within code, you'll write...

 

PEGraph1.Fontsize := gLarge;

 

 

DLL Declarations and Constants 

If you need to call ProEssentials DLL functions from within Delphi, be sure to add "Pegrpapi" to your uses clause.

 

In Builder, you can include the standard "C" header file "PEGRPAPI.H" as needed.

 

 

Don't use property windows!

We recommend that you set only a few properties (if any) in the property window/object browser. This has many advantages: 1) If you have problems, you can email/fax us your code and we have a record of what properties you are setting; 2) If you go back to your code a couple months later, or someone else inherits your project, they have a documented list of properties you have set; 3) If you ever port your code to another IDE, its very easy to just reformat your current code; 4) In the case where a VB or Delphi form-file gets corrupted (this does happen occasionally) you won't lose your property adjustments; and 5) You will avoid potentially hard-to-find bugs due to setting a property both in the property window and in code.

 

The bottom line is that property windows may seem to be faster, yet, in the long run, coding your property settings will definitely result in the safest, and most maintainable implementation.