CanvasFillRule = enum
  cfrNonZero = "nonzero", cfrEvenOdd = "evenodd"

CanvasTextAlign = enum
  ctaStart = "start", ctaEnd = "end", ctaLeft = "left", ctaRight = "right",
  ctaCenter = "center"

PaintCommand = enum
  pcSetDimensions, pcFillRect, pcStrokeRect, pcFillPath, pcStrokePath,
  pcFillText, pcStrokeText