anchor.diff:        ..on(Message.clearDrawing, (_) => clearDrawing())
         ..on(Message.undoLast, (_) => undoLast())
         ..on(Message.existingCanvasLayers, (x) => existingCanvasLayers(x));
  -
     }
   
     drawPoint(DrawPoint drawPoint) {
  
positive.code: 
    matchStartColor(int pixelPos, ImageData imgData, HexColor color) {
      var r = imgData.data[pixelPos];
      var g = imgData.data[pixelPos+1];
      var b = imgData.data[pixelPos+2];
  
      return (r == color.r && g == color.g && b == color.b);
    }
  
    colorPixel(int pixelPos, ImageData imgData, HexColor color) {
      imgData.data[pixelPos] = color.r;
      imgData.data[pixelPos+1] = color.g;
      imgData.data[pixelPos+2] = color.b;
      imgData.data[pixelPos+3] = 255;
    }
  
    fill(num x, num y, String color) {
  
negative.code: 
      strokeCanvasLayers();
    }
  }
  