Panel showing Enabled/Disabled in Children

Problem/Question/Abstract:

Often you disable all Controls within a Panel by simply setting the Enabled Property of the Panel. It works, however the user does not get any visual feedback.

Answer:

The following component code simply extends the Delphi Panel to properly show the Enabled State (True/False) within its children.

Extending the control is very simple. All  we need to do is to override and extend the default SetEnabled procedure. The new procedure will first call the original version and then rotate through all children and copy the state.

There is one drawback although, if there is a disabled control (XYZ) on the panel, you then disable the panel and enbale it again, the control (XYZ) will be enabled, too.

Anyway, often it is very useful. Here you go:

unit uRealPanel;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ExtCtrls;

type
  TRealPanel = class(TPanel)
  private
  protected
    procedure SetEnabled(Value: Boolean); override;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('gate(n)etwork', [TRealPanel]);
end;

{ TRealPanel }

procedure TRealPanel.SetEnabled(Value: Boolean);
var
  I: Integer;
begin
  inherited;
  if csDesigning in ComponentState then
    Exit;
  for I := 0 to Pred(ControlCount) do
    if Controls[I] is TWinControl then
      (Controls[I] as TWinControl).Enabled := Value;
end;

end.