Context constructor
      
      Context({ 
    
    
- required PdfDocument document,
- PdfPage? page,
- PdfGraphics? canvas,
Implementation
factory Context({
  required PdfDocument document,
  PdfPage? page,
  PdfGraphics? canvas,
}) =>
    Context._(
      document: document,
      page: page,
      canvas: canvas,
      inherited: HashMap<Type, Inherited>(),
    );