Eigene Komponete von TEdit ableiten?

[SirThornberry]

so, hab geschaut. TCustomEdit hat die Methode "Change". Diese also überschreiben (darin die Farbe setzen) und dann inherited.

@mkinzler: Wie ich gerade sehe hast du auch vergessen die Farben zu initialisieren mit standardwerten.

Delphi-Quellcode:

type
  TEdit = class(StdCtrls.TEdit)
  protected
    fCheckEmpty: Boolean;
    fEmptyColor: TColor;
    fNonEmptyColor: TColor;
    procedure Change; override;
    procedure FSetCheckEmpty(AValue: Boolean);
    procedure FSetColor(AType: Integer; AColor: TColor);
  public
    constructor Create(AOwner: TComponent); override;
  published
    property CheckEmpty: Boolean read fCheckEmpty write fSetCheckEmpty default True;
    property ColorEmpty: TColor Index 0 read fEmptyColor write FSetColor;
    property ColorNonEmpty: TColor Index 1 read fNonEmptyColor write FSetColor;
  end;
[...]
constructor TEdit.Create(AOwner: TComponent);
begin
  fCheckEmpty := True;
  fEmptyColor := clBlue;
  inherited Create(AOwner);
  fNonEmptyColor := Color;
  Change;
end;

procedure TEdit.Change;
var LColor: TColor;
begin
  if fCheckEmpty then
  begin
    if Self.Text = '' then
      LColor := fEmptyColor
    else
      LColor := fNonEmptyColor;
  end else
    LColor := fNonEmptyColor;
  if LColor <> Color then
    Color := LColor;
  inherited;
end;

procedure TEdit.FSetCheckEmpty(AValue: Boolean);
begin
  if AValue <> fCheckEmpty then
  begin
    fCheckEmpty := AValue;
    Change;
  end;
end;

procedure TEdit.FSetColor(AType: Integer; AColor: TColor);
  procedure LSetVal(var ACurrVal: TColor);
  begin
    if (ACurrVal <> AColor) then
    begin
      ACurrVal := AColor;
      if fCheckEmpty then
        Change;
    end;
  end;
begin
  case AType of
    0: LSetVal(fEmptyColor);
    1: LSetVal(fNonEmptyColor);
  end;
end;