Reference TTheme

  TTheme = class
  public
    { Calculate the actual theme color }
    function CalcColor(Widget: TWidget; Color: TThemeColor): TColorF; virtual; abstract;
    { Calculate the size of a widget }
    function CalcSize(Widget: TWidget; Part: TThemePart): TSizeF; virtual; abstract;
    { Calculate the height of text in the widget }
    function CalcTextHeight: Float; virtual; abstract;
    { Calculate how wide text is when drawn in the widget, including spaces }
    function CalcTextWidth(Widget: TWidget; const Text: string): Float; virtual; abstract;
    { Render the widget }
    procedure Render(Widget: TWidget; Stage: TPaintStage); virtual; abstract;
    { Render a hint for the widget }
    procedure RenderHint(Widget: TWidget; Opacity: Float); virtual; abstract;
    { Calculate where the close button of a window is, relative to the top left
      of the window. An empty rectangle means the theme has none. }
    function CalcCloseRect(Window: TWindow): TRectF; virtual;
    { Draw what follows transformed by a matrix, until PopMatrix. The matrix is
      applied before the transform already in use. }
    procedure PushMatrix(Matrix: IMatrix); virtual;
    { Put the transform back as it was before PushMatrix }
    procedure PopMatrix; virtual;
  end;