Komponente zeichnet sich nicht neu, bei Font Änderung

[Nightshade]

Delphi-Quellcode:

unit StatusScroll;

interface

uses
  SysUtils, Classes, Controls, Graphics;

type
  TStatusScroll = class(TGraphicControl)
  private
    FLines: TStringList;
    FFont: TFont;
    FRowCount: Integer;
    FAlignment: TAlignment;
    procedure SetLines(const Value: TStringList);
    procedure SetFont(const Value: TFont);
    procedure SetAlignment(const Value: TAlignment);
    { Private-Deklarationen }
  protected
    procedure Paint; override;
    { Protected-Deklarationen }
  public
    constructor Create(AOwner : TComponent); override;
    destructor destroy; override;
    { Public-Deklarationen }
  published
    property Lines : TStringList read FLines write SetLines;
    property Font : TFont read FFont write SetFont;
    property RowCount : Integer read FRowCount;
    property Alignment : TAlignment read FAlignment write SetAlignment;
    { Published-Deklarationen }
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Beispiele', [TStatusScroll]);
end;

{ TStatusScroll }

constructor TStatusScroll.Create(AOwner: TComponent);
begin
  inherited;
  FFont := TFont.Create;
  FLines := TStringList.Create;
end;

destructor TStatusScroll.destroy;
begin
  FreeAndNil(FFont);
  FreeAndNIL(FLines);
  inherited;
end;

procedure TStatusScroll.Paint;
var FTextHeight, FTextWidth, t : integer;
    bmp : TBitmap;
begin
  inherited;
  with canvas do begin
    Brush.Style:=BSClear;
    Font.Assign(FFont);
    Pen.Color:=Font.Color;
    FTextHeight := TextHeight('Ü,');
    FRowCount := trunc( height / ( FTextHeight + 4) );
    For t:= 0 to FRowCount-1 do begin
      if ( t <= Flines.Count -1 ) then begin
        FTextwidth := TextWidth(Flines.strings[t]);
        case FAlignment of
          taLeftJustify:  TextOut(2,( t * ( FTextHeight + 4 ) + 2 ),Flines.Strings[t]);
          taRightJustify: TextOut(width - FTextwidth -2,( t * ( FTextHeight + 4 ) + 2 ),Flines.Strings[t]);
          taCenter:       TextOut(trunc ( (width - FTextwidth -4) /2 ),( t * ( FTextHeight + 4 ) + 2 ),Flines.Strings[t]);
        end;
      end;
    end;
  end;
end;

procedure TStatusScroll.SetAlignment(const Value: TAlignment);
begin
  FAlignment := Value;
  Paint;
end;

procedure TStatusScroll.SetFont(const Value: TFont);
begin
  FFont.Assign(Value);
  Paint;
end;

procedure TStatusScroll.SetLines(const Value: TStringList);
begin
  FLines.Assign(Value);
  Paint;
end;

end.

Das Problem was ich habe, ist das Ändern der Font-Einstellungen.

Ich sehe die Änderungen erst, wenn ich einmal das Formular mit einem anderem Fenster überdeckt habe.

Wo ist mein Fehler ?