...CM_MOUSEENTER und CM_MOUSELEAVE in einer Komponente verwenden?

{
 Folgende unit ist eine visuelle Komponente abgeleitet von TImage, welche
 zusätzlich die 2 Ereignisse OnMouseEnter und OnMouseLeave beinhaltet.
}

{
 The following unit is a visual component inherited of TImage, which has the
 2 additional events OnMouseEnter and OnMouseLeave.
}

unit ImageEx;

interface

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

type
  TImageEx = class (TImage)
  private
    { Private declarations }
    FOnMouseLeave: TNotifyEvent;
    FOnMouseEnter: TNotifyEvent;
    procedure CMMouseEnter(var msg: TMessage);
      message CM_MOUSEENTER;
    procedure CMMouseLeave(var msg: TMessage);
      message CM_MOUSELEAVE;
  protected
    { Protected declarations }
    procedure DoMouseEnter; dynamic;
    procedure DoMouseLeave; dynamic;
  public
    { Public declarations }
  published
    { Published declarations }
    property OnMouseEnter: TNotifyEvent read FOnMouseEnter write FOnMouseEnter;
    property OnMouseLeave: TNotifyEvent read FOnMouseLeave write FOnMouseLeave;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Additional', [TImageEx]);
end;

{ TImageEx }

procedure TImageEx.CMMouseEnter(var msg: TMessage);
begin
  DoMouseEnter;
end;

procedure TImageEx.CMMouseLeave(var msg: TMessage);
begin
  DoMouseLeave;
end;

procedure TImageEx.DoMouseEnter;
begin
  if Assigned(FOnMouseEnter) then FOnMouseEnter(Self);
end;

procedure TImageEx.DoMouseLeave;
begin
  if Assigned(FOnMouseLeave) then FOnMouseLeave(Self);
end;

end.

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