Graphics - Working with TCanvas/it

SelectObject(Canvas.Handle, GetStockObject(DEFAULT_GUI_FONT));

..
uses ... windows ...
..
var Image1: TImage;
    TextBox: TRect;
    Text: String;
...
Text:= ...;
// Prima calcoliamo la dimensione del testo, poi lo disegniamo:
TextBox:= Rect(10, 10, Image1.Width - 10, High(Integer));
// questa istruzione ricalcola TextBox.Bottom:
DrawText(Image1.canvas.Handle, PChar(Text), Length(Text),
  TextBox, DT_WORDBREAK or DT_INTERNAL or DT_CALCRECT);
// questa istruzione scrive il testo
DrawText(Image1.Canvas.Handle, PChar(Text), Length(Text),
  TextBox, DT_WORDBREAK or DT_INTERNAL);

Canvas.Font.Quality := fqNonAntialiased;

procedure PaintAliased(Canvas: TCanvas; x,y: integer; const TheText: string);
var
  w,h: integer;
  IntfImg: TLazIntfImage;
  Img: TBitmap;
  dy: Integer;
  dx: Integer;
  col: TFPColor;
  FontColor: TColor;
  c: TColor;
begin
  w:=0;
  h:=0;
  Canvas.GetTextSize(TheText,w,h);
  if (w<=0) or (h<=0) then exit;
  Img:=TBitmap.Create;
  IntfImg:=nil;
  try
    // paint text to a bitmap
    Img.Masked:=true;
    Img.SetSize(w,h);
    Img.Canvas.Brush.Style:=bsSolid;
    Img.Canvas.Brush.Color:=clWhite;
    Img.Canvas.FillRect(0,0,w,h);
    Img.Canvas.Font:=Canvas.Font;
    Img.Canvas.TextOut(0,0,TheText);
    // get memory image
    IntfImg:=Img.CreateIntfImage;
    // replace gray pixels
    FontColor:=ColorToRGB(Canvas.Font.Color);
    for dy:=0 to h-1 do begin
      for dx:=0 to w-1 do begin
        col:=IntfImg.Colors[dx,dy];
        c:=FPColorToTColor(col);
        if c<>FontColor then
          IntfImg.Colors[dx,dy]:=colTransparent;
      end;
    end;
    // create bitmap
    Img.LoadFromIntfImage(IntfImg);
    // paint
    Canvas.Draw(x,y,Img);
  finally
    IntfImg.Free;
    Img.Free;
  end;
end;