how to add a property to a component that will reflect on the object inspector

in De开发者_如何学Clphi 7 , when adding a propery to an object, how is it possible to see that property in the object inspector?

Make the property published. For instance,

private
  FMyProperty: integer;
published
  property MyProperty: integer read FMyProperty write FMyProperty;

Often, you need to repaint the control (or do some other processing) when a property is changed. Then you can do

private
  FMyProperty: integer;
  procedure SetMyProperty(MyProperty: integer);
published
  property MyProperty: integer read FMyProperty write SetMyProperty;

...

procedure TMyControl.SetMyProperty(MyProperty: integer);
begin
  if FMyProperty <> MyProperty then
  begin
    FMyProperty := MyProperty;
    Invalidate; // for example
  end;
end;

Add that property to the published section, it will make it appear on the Object Inspector, like this:

TMyComponent = class(TComponent)
 ...
published
  property MyProperty: string read FMyProperty write SetMyProperty;

From the docs:

Properties declared in a published section of the component's class declaration are editable in the Object Inspector at design time.

Don't forget that the Component needs to get registered within Delphi (preferable in a Design Time Package) or you you won't see anything in the Object Inspector at all !!!

I mean ... I can create a new TPanel descendant called TMyPanel and add a new Published property to it :

type
  TPanel1 = class(TPanel)
  private
    FMyName: String;
    { Private declarations }
  protected
    { Protected declarations }
  public
    { Public declarations }
  published
    { Published declarations }
    property MyName : String read FMyName write FMyName;
  end;

but that property won't get displayed in the Object Inspector if you havn't registered the new class using RegisterComponent :

procedure Register;
begin
  RegisterComponents('Samples', [TPanel1]);
end;

Just to be complete :-)