/////////////////// отрисовка скина
  h := FSkinBitmap.Height div 4;
  w := FSkinBitmap.Width;
  if FSkinTransparent then
  begin
    DrawParentBackground(Handle, FCanvas.Handle, @RC);
    case State of
      bsDisabled:
        TransparentBlt(FCanvas.Handle, 0, 0, w, h, FSkinBitmap.Canvas.Handle, 0, 0, w, h, FSkinTransparentColor);
      bsUp:
        TransparentBlt(FCanvas.Handle, 0, 0, w, h, FSkinBitmap.Canvas.Handle, 0, h, w, h, FSkinTransparentColor);
      bsOver:
        TransparentBlt(FCanvas.Handle, 0, 0, w, h, FSkinBitmap.Canvas.Handle, 0, 2*h, w, h, FSkinTransparentColor);
      bsDown:
        TransparentBlt(FCanvas.Handle, 0, 0, w, h, FSkinBitmap.Canvas.Handle, 0, 3*h, w, h, FSkinTransparentColor);
    end;
  end else
  begin
    case State of
      bsDisabled:
        BitBlt(FCanvas.Handle, 0, 0, w, h, FSkinBitmap.Canvas.Handle, 0, 0, SRCCOPY);
      bsUp:
        BitBlt(FCanvas.Handle, 0, 0, w, h, FSkinBitmap.Canvas.Handle, 0, h, SRCCOPY);
      bsOver:
        BitBlt(FCanvas.Handle, 0, 0, w, h, FSkinBitmap.Canvas.Handle, 0, 2*h, SRCCOPY);
      bsDown:
        BitBlt(FCanvas.Handle, 0, 0, w, h, FSkinBitmap.Canvas.Handle, 0, 3*h, SRCCOPY);
    end;
  end;
  //////////////////

...
  TMyButton = class(TButton)
  private
    FCanvas: TCanvas;
...
    FSkinBitmap: TBitmap;
    FTransparent: Boolean;
    FTransparentColor: TColor;
    procedure SetSkinBitmap(const ABitmap: TBitmap);
    procedure SetTransparent(const AValue: Boolean);
    procedure SetTransparentColor(const AColor: TColor);
...
  protected
    procedure CreateParams(var Params: TCreateParams); override;
...
  public
...
  published
    property SkinBitmap: TBitmap read FSkinBitmap write SetSkinBitmap;
    property Transparent: Boolean read FTransparent write SetTransparent default false;
    property TransparentColor: TColor read FTransparentColor write SetTransparentColor default clNone;
  end;
...

implementation

...

procedure TMyButton.CreateParams(var Params: TCreateParams);
begin
  inherited CreateParams(Params);
  with Params do
    Style := Style or BS_OWNERDRAW;
end;

procedure TMyButton.SetSkinBitmap(const ABitmap: TBitmap);
begin
  FSkinBitmap.Assign(ABitmap);
  Invalidate;
end;

procedure TMyButton.SetTransparent(const AValue: Boolean);
begin
  FTransparent := AValue;
  Invalidate;
end;

procedure TMyButton.SetTransparentColor(const AColor: TColor);
begin
  FTransparentColor := AColor;
  Invalidate;
end;

...

procedure TMyButton.CNDrawItem(var Message: TWMDrawItem);
var
...
  h, w: integer;
begin
...

  /////////////////// отрисовка скина
  h := FSkinBitmap.Height div 4;
  w := FSkinBitmap.Width;
  FSkinBitmap.Transparent := FTransparent;
  FSkinBitmap.TransparentColor := FTransparentColor;
  case State of
    bsDisabled:
      FCanvas.CopyRect(Rect(0, 0, w, h), FSkinBitmap.Canvas, Rect(0, 0, w, h));
    bsUp:
      FCanvas.CopyRect(Rect(0, 0, w, h), FSkinBitmap.Canvas, Rect(0, h, w, 2*h));
    bsOver:
      FCanvas.CopyRect(Rect(0, 0, w, h), FSkinBitmap.Canvas, Rect(0, 2*h, w, 3*h));
    bsDown:
      FCanvas.CopyRect(Rect(0, 0, w, h), FSkinBitmap.Canvas, Rect(0, 3*h, w, 4*h));
    end;
  //////////////////

...
end;

...

end.

Bitmap := TBitmap.Create;
Bitmap.Height := 80;
Bitmap.Width := 82;
Bitmap.PixelFormat := pf24bit;

MyButton.SkinBitmap := Bitmap;
MyButton.Transparent := true;
MyButton.TransparentColor := $00ff00ff;

type
  TGradientDirection=(gdHorizontal,gdVertical);
procedure GradientFillCanvas(Canvas:TCanvas;StartColor,EndColor:TColor;const ARect:TRect;Direction:TGradientDirection);
const
  cGradientDirections:array[TGradientDirection] of Cardinal=
  (GRADIENT_FILL_RECT_H,GRADIENT_FILL_RECT_V);
type
  TTriVertex=packed record
    x:LongInt;
    y:LongInt;
    Red:Word;
    Green:Word;
    Blue:Word;
    Alpha:Word;
  end;
var
  Vertexes:array[0..1] of TTriVertex;
  GradientRect:TGradientRect;
begin
  StartColor:=ColorToRGB(StartColor);
  EndColor:=ColorToRGB(EndColor);

  Vertexes[0].x:=ARect.Left;
  Vertexes[0].y:=ARect.Top;
  Vertexes[0].Red:=GetRValue(StartColor)shl 8;
  Vertexes[0].Blue:=GetBValue(StartColor)shl 8;
  Vertexes[0].Green:=GetGValue(StartColor)shl 8;
  Vertexes[0].Alpha:=0;

  Vertexes[1].x:=ARect.Right;
  Vertexes[1].y:=ARect.Bottom;
  Vertexes[1].Red:=GetRValue(EndColor)shl 8;
  Vertexes[1].Blue:=GetBValue(EndColor)shl 8;
  Vertexes[1].Green:=GetGValue(EndColor)shl 8;
  Vertexes[1].Alpha:=0;

  GradientRect.UpperLeft:=0;
  GradientRect.LowerRight:=1;

  GradientFill(Canvas.Handle,Windows.PTriVertex(@Vertexes[0])^,2,@GradientRect,1,cGradientDirections[Direction]);
end;

 DRON