Reference TAlphaPicker

  TAlphaPicker = class(TCustomColorControl)
  protected
    function GetColorValue: TColorB; override;
    procedure SetColorValue(Value: TColorB); override;
    procedure ChangeMouse(X, Y: Integer); override;
    procedure Draw; override;
  public
    { Create a new alpha picker }
    constructor Create(AOwner: TComponent); override;
    { The color combined with the selected alpha }
    property ColorValue;
  published
    { When true a border is drawn around the picker }
    property Border: Boolean read FBorder write SetBorder default False;
    { The color whose alpha is picked }
    property Color;
    { The size of the checkerboard squares }
    property CheckerSize: Integer read FCheckerSize write SetCheckerSize default 10;
    { The selected alpha from 0 for transparent to 1 for opaque }
    property ColorAlpha: Float read FColorAlpha write SetColorAlpha;
    { Show a gradient to pick from or only the color at its current alpha }
    property Style: TAlphaStyle read FStyle write SetStyle default asGradient;
    property Align;
    property Anchors;
    property BorderSpacing;
    property Constraints;
    property Enabled;
    property ParentShowHint;
    property ShowHint;
    property Visible;
    property OnChange;
    property OnChangeBounds;
    property OnClick;
    property OnMouseDown;
    property OnMouseEnter;
    property OnMouseLeave;
    property OnMouseMove;
    property OnMouseUp;
    property OnResize;
  end;