FastReport contains a set of common controls, which can be placed on the dialogue form inside a report. They are the following elements:

TfrxLabelControl

TfrxEditControl

TfrxMemoControl

TfrxButtonControl

TfrxCheckBoxControl

TfrxRadioButtonControl

TfrxListBoxControl

TfrxComboBoxControl

TfrxDateEditControl

TfrxBevelControl

TfrxPanelControl

TfrxGroupBoxControl

TfrxBitBtnControl

TfrxSpeedButtonControl

TfrxMaskEditControl

TfrxCheckListBoxControl

These elements correspond to the standard controls of the Delphi component palette. If standard functionality does not satisfy you, you can create your own common control and use it in your reports.

The basic class for all common controls is the TfrxDialogControl class described in the frxClass file:

TfrxDialogControl = class (TfrxReportComponent)

protected

public

published

end;

To create your own element, you should inherit from this class and override at least the constructor and the “GetDescription” methods. It will be necessary to create a common control and initialize it via the “InitControl” method in the constructor. The GetDescription method is to return the description of the common control. As you can see from the TfrxDialogControl class's description, it already contains a huge number of properties and methods in the public section. You need to transfer the necessary properties/events into the “published” section of your common control, and also to create new properties, which are typical for your element.

Registration and deleting of the common control is performed with the help of the frxObjects global object's methods declared in the frxDsgnIntf file:

frxObjects.RegisterObject(ClassRef: TfrxComponentClass; ButtonBmp:

TBitmap; const CategoryName: String = '');

frxObjects.Unregister(ClassRef: TfrxComponentClass);

During registration, you should specify control class' name, its picture, and the name of a category, to which it should be placed. If the name of a category is not specified, the control is placed in the basic component palette. The ButtonBmp size should be 22x22 pixels.

Categories allow grouping the objects' pictures in the toolbar, according to their functions. The categories are also used for saving space in the toolbar, since its size is limited. Nevertheless, it can contain a large number of objects.

To register a category, use the following method of the “frxObjects” object described in the “frxDsgnIntf” file:

frxObjects.RegisterCategory( const CategoryName: String ; ButtonBmp:

TBitmap; const ButtonHint: String ; ImageIndex: Integer = -1);

The first parameter is the name of a category. This name is used for identification of the category only and does not appear anywhere else. It should also be used when calling the “frxObjects.RegisterObject” procedure, if you want to place the registered object inside the given category. The second parameter is a picture; its size is 22x22 pixels. The third parameter is the category's description; it is displayed as a hint, if the button with a category is selected by the cursor.

Let us examine an example of the common control, which realizes simplified functionality of the standard Delphi TBitBtn control.

uses frxClass, frxDsgnIntf, Buttons;

type

constructor TfrxBitBtnControl.Create(AOwner: TComponent);

begin

end;

class function TfrxBitBtnControl.GetDescription: String ;

begin

end;

procedure TfrxBitBtnControl.SetKind( const Value: TBitBtnKind);

begin

end;

function TfrxBitBtnControl.GetKind: TBitBtnKind;

begin

end;

var

initialization

finalization

end.