print.js

saveCanvasImage() {
                  var dataUrl = this.canvasElement.toDataURL();
                  var imageData = this.canvasElement.toDataURL('image/jpeg').replace(/^data:image\/(png|jpg|jpeg);base64,/, ""); //remove mimetype
                   window["DatecsPrinter"].printImage(
          imageData, //base64
          canvas.width, 
          canvas.height, 
          1, 
          function() {
           console.log("Printed");
          },
          function(error) {
              alert(JSON.stringify(error));
          }
      )
  };
                 
                  let ctx = this.canvasElement.getContext('2d');
                  ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); // Clears the canvas
                 
                  let name = new Date().getTime() + '.png';
                  let path = this.file.dataDirectory;
                  let options: IWriteOptions = { replace: true };
                 
                  var data = dataUrl.split(',')[1];
                  let blob = this.b64toBlob(data, 'image/png');
                 
                  this.file.writeFile(path, name, blob, options).then(res => {
                    this.storeImage(name);
                  }, err => {
                    console.log('error: ', err);
                  });
                }