getRatioPageCanvas :: ZoomMode -> PageDimension -> CanvasDimension -> (Double,Double)
getRatioPageCanvas zmode (PageDimension (Dim w h)) (CanvasDimension (Dim w' h')) = 
  case zmode of 
    Original -> (1.0,1.0)
    FitWidth -> (w'/w,w'/w)
    FitHeight -> (h'/h,h'/h)
    Zoom s -> (s,s)

-- |
getRatioPageCanvas :: ZoomMode -> PageDimension -> CanvasDimension -> (Double,Double)
getRatioPageCanvas zmode (PageDimension (Dim w h)) (CanvasDimension (Dim w' h')) = 
  case zmode of 
    Original -> (1.0,1.0)
    FitWidth -> (w'/w,w'/w)
    FitHeight -> (h'/h,h'/h)
    Zoom s -> (s,s)

-- |
getRatioPageCanvas zmode (PageDimension (Dim w h)) (CanvasDimension (Dim w' h')) = 
  case zmode of 
    Original -> (1.0,1.0)
    FitWidth -> (w'/w,w'/w)
    FitHeight -> (h'/h,h'/h)
    Zoom s -> (s,s)

-- |