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...assign an event handler to all components?
Autor: Thomas Stutz
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Tip Rating (5):  
     


{
  This example shows how to assign a OnContextPopup event
  handler to all components at runtime using SetMethodProp().
  (Here: OnContextPopup event handler)
}

{
  Diese Beispiel zeigt, wie man mit Hilfe von SetMethodProp()
  allen Komponenten ein Ereignis (hier: OnContextPopup Ereignis)
  zur Laufzeit zuweisen kann.
}


  
private
    
{ Private declarations }
    
procedure AssignOnContextPopupEvent;
    procedure OnContextPopup(Sender: TObject; MousePos: TPoint;
     var Handled: Boolean);
  public
    
{ Public declarations }
  
end;

var
  
Form1: TForm1;

implementation

{$R *.dfm}

uses
  
TypInfo;

procedure TForm1.OnContextPopup(Sender: TObject; MousePos: TPoint;
  var Handled: Boolean);
begin
  with 
Sender as TComponent do
    
ShowMessage(Name + ' right-clicked!');
end;

procedure TForm1.AssignOnContextPopupEvent;
var
  
i: Integer;
  PropInfo: PPropInfo;
  Method: TMethod;
  PEvent: ^TContextPopupEvent;
begin
  for 
i := 0 to ComponentCount - 1 do
  begin
    
PropInfo := GetPropInfo(Components[i].ClassInfo, 'OnContextPopup');
    if (PropInfo <> niland (PropInfo^.PropType^^.Kind = tkMethod) then
    begin
      
Method := GetMethodProp(Components[i], PropInfo);
      if not Assigned(Method.Code) then
      begin
        
PEvent := @Method.Code;
        PEvent^ := OnContextPopup;
        Method.Data := Self;
        SetMethodProp(Components[i], PropInfo, Method);
      end;
    end;
  end;
end;

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

 

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