private void InitializeCategoryFilterButton(int resourceId)
        {
            var category    = PoiCategoryHelper.GetCategory(resourceId);
            var imageButton = FindViewById <ImageButton>(resourceId);

            imageButton.SetOnClickListener(this);
            bool enabled = _context.Settings.Categories.Contains(category);

            imageButton.SetImageResource(PoiCategoryHelper.GetImage(category, enabled));

            _imageButtonCategoryFilter.Add(category, imageButton);
        }
        private void OnCategoryFilterChanged(int resourceId)
        {
            var poiCategory = PoiCategoryHelper.GetCategory(resourceId);
            var imageButton = _imageButtonCategoryFilter[poiCategory];

            if (_context.Settings.Categories.Contains(poiCategory))
            {
                _context.Settings.Categories.Remove(poiCategory);
                imageButton.SetImageResource(PoiCategoryHelper.GetImage(poiCategory, false));
            }
            else
            {
                _context.Settings.Categories.Add(poiCategory);
                imageButton.SetImageResource(PoiCategoryHelper.GetImage(poiCategory, true));
            }

            _context.Settings.NotifySettingsChanged(ChangedData.PoiFilterSettings);
        }