setFilter method Null safety

Future<int?> setFilter(
  1. String assetUrl
)

Specify material filter effect

Parameters:

assetUrl can be an asset resource address defined in Flutter such as 'images/watermark_img.png' or an online image address

Note: PNG format must be used

Implementation

Future<int?> setFilter(String assetUrl // Resource address in `assets`
    ) async {
  String imageUrl = assetUrl;
  String type = 'network'; // Online image by default
  if (assetUrl.indexOf('http') != 0) {
    type = 'local';
  }
  return _channel
      .invokeMethod('setFilter', {"imageUrl": imageUrl, "type": type});
}