nl_tokens: Gets the pixel ratio of the canvas .
pl_tokens: function ( canvas ) { var context = canvas . getContext ( '2d' ) , devicePixelRatio = window . devicePixelRatio || 1 , backingStorePixelRatio = context . webkitBackingStorePixelRatio || context . mozBackingStorePixelRatio || <mask> . msBackingStorePixelRatio || context . oBackingStorePixelRatio || context . backingStorePixelRatio || 1 ; return devicePixelRatio / backingStorePixelRatio ; }