(Missing feature) Flutter onLongPressUp emulation

long_press_up.dart

// Currently Flutter (0.8.2) doesn't provide an onLongPressUp method in GestureDetector as you can see here https://github.com/flutter/flutter/pull/18949
// So I came up with this solution

import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';

class LongPressUp extends SingleChildRenderObjectWidget {
  final VoidCallback _callback;

  LongPressUp(this._callback);

  @override
  RenderLongPressUp createRenderObject(BuildContext context) =>
      RenderLongPressUp(this._callback);
}

class RenderLongPressUp extends RenderConstrainedBox {
  final VoidCallback _callback;
  RenderLongPressUp(this._callback)
      : super(additionalConstraints: const BoxConstraints.expand());

  // Makes this render box hittable so that we'll get pointer events.
  @override
  bool hitTestSelf(Offset position) => true;

  @override
  void handleEvent(PointerEvent event, BoxHitTestEntry entry) {
    if (event is PointerUpEvent || event is PointerCancelEvent) {
      _callback();
    }
  }
}

// You can call this by adding LongPressUp widget as a GestureDetector child like this

GestureDetector(
  onTapDown: (details) {
    print("tapDown");
  },
  onTapUp: (details) {
    print("tapUp");
  },
  onTap: () {
    print("tap");
  },
  onTapCancel: () {
    print("tapCancel");
  },
  onLongPress: () {
    print("longPress");
  },
  child: LongPressUp(() {     //
    print("onLongPressUp");   // NEW FEATURE
  }),                         //
)