Replacing Buttons

Steps to show how to use a third party button control.

In order to use alternate buttons controls you have to handle two events. Some controls require additional events to be handled.

OnGetControlClass

OnInitControl

Example

1. Start your IDE of choice

2. Create a new application

3. Drop a TButton and TJSDialog on the Form

4. Double click the button to create an OnClick handler

5. In the OnClick handler put the following code:

       JSDialog1.Execute;

6. Enter in a title, main instruction and content

7. In the implementation section of the code enter create a new button class descending from TBitBtn (doesn't have to descend from TBitBtn):

    type
      TMyButton = class(TBitBtn)
    end;

Add Buttons to the implementation uses clause.

8. Select the events tab

9. Double click on the OnGetControlClass event and enter in the following code:

    if AControlType = ctButton then
      ControlClass := TMyButton;

10, Double click on the OnInitControl event and enter in the following code:

    var
      lBtn: TMyButton;
      lBI: TJSCustomButtonItem;
    begin
      if ControlType = ctButton then
      begin
        lBtn := TMyButton(Control);
        lBI := TJSCustomButtonItem(ControlItem);
        lBtn.Caption := lBI.Caption;
        lBtn.Default := lBI.Default;
        lBtn.Cancel := lBI.Cancel;
        lBtn.ModalResult := lBI.ModalResult;
        lBtn.Font.Color := clRed;
        Handled := True;
      end;
    end;

11. Run the application

The captions of the dialog buttons should now be red.

Full unit source follows

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, JSDialog, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    JSDialog1: TJSDialog;
    procedure Button1Click(Sender: TObject);
    procedure JSDialog1GetControlClass(Sender: TObject; ControlType: TControlType; var ControlClass: TControlClass);
    procedure JSDialog1InitControl(Sender: TObject; ControlType: TControlType; Control: TControl;
      ControlItem: TCollectionItem; var Handled: Boolean);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

uses
    Buttons
  ;

{$R *.dfm}

type
  TMyButton = class(TBitBtn)

  end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  JSDialog1.Execute;
end;

procedure TForm1.JSDialog1GetControlClass(Sender: TObject; ControlType: TControlType; var ControlClass: TControlClass);
begin
  if ControlType = ctButton then
    ControlClass := TMyButton;
end;

procedure TForm1.JSDialog1InitControl(Sender: TObject; ControlType: TControlType; Control: TControl;
 ControlItem: TCollectionItem; var Handled: Boolean);
var
  lBtn: TMyButton;
  lBI: TJSCustomButtonItem;
begin
  if ControlType = ctButton then
  begin
    lBtn := TMyButton(Control);
    lBI := TJSCustomButtonItem(ControlItem);
    lBtn.Caption := lBI.Caption;
    lBtn.Default := lBI.Default;
    lBtn.Cancel := lBI.Cancel;
    lBtn.ModalResult := lBI.ModalResult;
    lBtn.Font.Color := clRed;
    Handled := True;
  end;
end;

end.

Group

Using Third Party Controls

Links

Using Third Party Controls, Example

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