fabricjs: retain the correct indexes of an object's image filters after loadFromJSON

I managed to get this working by changing the way I applied and retrieved the filters (by type rather than index). I simply checked to see if the filter existed (by 'type' not index), then spliced the filter at the desired index.

Changed this function...

getFilter(index) { 
   var obj = canvas.getActiveObject();
   return obj.filters[index];
}

to this...

getFilter(type) { 
  var obj = canvas.getActiveObject();
  if (obj) {
    filter = null;
    obj.filters.forEach(function(f) {
      if (f.type == type) {
        filter = f;
      }
    });
    return filter;
  }
}

---

Changed this function...

applyFilter(index, filter) {
  var object = canvas.getActiveObject();
  object.filters[index] = filter;
  object.applyFilters();
  canvas.renderAll();
}

to this...

applyFilter(type, filterIndex, filter) {
  var obj = canvas.getActiveObject();
  var indexExists = false;
  var filterFound = false;

  if (obj) {
    obj.filters.forEach(function(f, i) {
      if (f.type == type) {
        filterFound = true;
        obj.filters[i] = filter;
      } 
      if (filterIndex == i) {
        indexExists = true;
      } 
    });

    if (!filterFound && indexExists) {
      obj.filters.splice(filterIndex, 0, filter);
    } else if (!filterFound && !indexExists) {
      obj.filters[filterIndex] = filter;
    }

  }
  obj.applyFilters();
  canvas.renderAll();
}

---

Changed this function...

applyFilterValue(index, prop, value) {
  var obj = canvas.getActiveObject();
  if (obj.filters[index]) {
    obj.filters[index][prop] = value;
    obj.applyFilters();
    canvas.renderAll();
  }
}

to this...

applyFilterValue(type, filterIndex, prop, value) {
  var obj = canvas.getActiveObject();
  if (obj) {
    obj.filters.forEach(function(f, i) {
      if (f.type == type) {
        obj.filters[i][prop] = value;
      }
    });
  }
  obj.applyFilters();
  canvas.renderAll();
}