packages/flutter/lib/src/gestures/gesture_settings.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:ui' as ui;
import 'package:flutter/foundation.dart';

/// The device specific gesture settings scaled into logical pixels.
///
/// This configuration can be retrieved from the window, or more commonly from a
/// [MediaQuery] widget.
///
/// See also:
///
///  * [ui.GestureSettings], the configuration that this is derived from.
@immutable
class DeviceGestureSettings {
  /// Create a new [DeviceGestureSettings] with configured settings in logical
  /// pixels.
  const DeviceGestureSettings({
    this.touchSlop,
  });

  /// Create a new [DeviceGestureSettings] from the provided [window].
  factory DeviceGestureSettings.fromWindow(ui.SingletonFlutterWindow window) {
    final double? physicalTouchSlop = window.viewConfiguration.gestureSettings.physicalTouchSlop;
    return DeviceGestureSettings(
      touchSlop: physicalTouchSlop == null ? null : physicalTouchSlop / window.devicePixelRatio
    );
  }

  /// The touch slop value in logical pixels, or `null` if it was not set.
  final double? touchSlop;

  /// The touch slop value for pan gestures, in logical pixels, or `null` if it
  /// was not set.
  double? get panSlop => touchSlop != null ? (touchSlop! * 2) : null;

  @override
  int get hashCode => ui.hashValues(touchSlop, 23);

  @override
  bool operator ==(Object other) {
    if (other.runtimeType != runtimeType)
      return false;
    return other is DeviceGestureSettings
      && other.touchSlop == touchSlop;
  }

  @override
  String toString() => 'DeviceGestureSettings(touchSlop: $touchSlop)';
}