code: function importLayer(file) {
    fileToCanvas(file, function(err, canvas) {
      if (err) {
        alert('Unable to load image file.');
        return;
      }
      if (canvas.width > maxSize || canvas.height > maxSize) {
        alert('Image is too large. The maximum supported size is ' +
          maxSize + ' by ' + maxSize + ' pixels.');
        return;
      }
  
      // Create layer.
      var asset = new Marzipano.DynamicAsset(canvas);
      var source = new Marzipano.SingleAssetSource(asset);
      var geometry = new Marzipano.EquirectGeometry([{ width: canvas.width }]);
      var layer = scene.createLayer({
        source: source,
        geometry: geometry
      });
  
      // Create a new effects object for the layer.
      var effects = layerEffects(layer);
  
      // Add layer into the view model.
      layers.unshift({
        name: file.name,
        layer: layer,
        effects: effects,
        canvas: canvas
      });
    });
  }
docs: Import a canvas into a layer.