drag_details.dart 7.14 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
// Copyright 2015 The Chromium 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' show Offset;

import 'package:flutter/foundation.dart';

import 'velocity_tracker.dart';

/// Details object for callbacks that use [GestureDragDownCallback].
///
/// See also:
///
///  * [DragGestureRecognizer.onDown], which uses [GestureDragDownCallback].
///  * [DragStartDetails], the details for [GestureDragStartCallback].
///  * [DragUpdateDetails], the details for [GestureDragUpdateCallback].
///  * [DragEndDetails], the details for [GestureDragEndCallback].
class DragDownDetails {
  /// Creates details for a [GestureDragDownCallback].
  ///
  /// The [globalPosition] argument must not be null.
23 24
  DragDownDetails({ this.globalPosition: Offset.zero })
    : assert(globalPosition != null);
25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

  /// The global position at which the pointer contacted the screen.
  ///
  /// Defaults to the origin if not specified in the constructor.
  final Offset globalPosition;

  @override
  String toString() => '$runtimeType($globalPosition)';
}

/// Signature for when a pointer has contacted the screen and might begin to
/// move.
///
/// The `details` object provides the position of the touch.
///
/// See [DragGestureRecognizer.onDown].
typedef void GestureDragDownCallback(DragDownDetails details);

/// Details object for callbacks that use [GestureDragStartCallback].
///
/// See also:
///
///  * [DragGestureRecognizer.onStart], which uses [GestureDragStartCallback].
///  * [DragDownDetails], the details for [GestureDragDownCallback].
///  * [DragUpdateDetails], the details for [GestureDragUpdateCallback].
///  * [DragEndDetails], the details for [GestureDragEndCallback].
class DragStartDetails {
  /// Creates details for a [GestureDragStartCallback].
  ///
  /// The [globalPosition] argument must not be null.
55
  DragStartDetails({ this.sourceTimeStamp, this.globalPosition: Offset.zero })
56
    : assert(globalPosition != null);
57

58 59 60 61 62 63
  /// Recorded timestamp of the source pointer event that triggered the drag
  /// event.
  ///
  /// Could be null if triggered from proxied events such as accessibility.
  final Duration sourceTimeStamp;

64 65 66 67 68
  /// The global position at which the pointer contacted the screen.
  ///
  /// Defaults to the origin if not specified in the constructor.
  final Offset globalPosition;

69 70 71 72
  // TODO(ianh): Expose the current position, so that you can have a no-jump
  // drag even when disambiguating (though of course it would lag the finger
  // instead).

73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102
  @override
  String toString() => '$runtimeType($globalPosition)';
}

/// Signature for when a pointer has contacted the screen and has begun to move.
///
/// The `details` object provides the position of the touch when it first
/// touched the surface.
///
/// See [DragGestureRecognizer.onStart].
typedef void GestureDragStartCallback(DragStartDetails details);

/// Details object for callbacks that use [GestureDragUpdateCallback].
///
/// See also:
///
///  * [DragGestureRecognizer.onUpdate], which uses [GestureDragUpdateCallback].
///  * [DragDownDetails], the details for [GestureDragDownCallback].
///  * [DragStartDetails], the details for [GestureDragStartCallback].
///  * [DragEndDetails], the details for [GestureDragEndCallback].
class DragUpdateDetails {
  /// Creates details for a [DragUpdateDetails].
  ///
  /// The [delta] argument must not be null.
  ///
  /// If [primaryDelta] is non-null, then its value must match one of the
  /// coordinates of [delta] and the other coordinate must be zero.
  ///
  /// The [globalPosition] argument must be provided and must not be null.
  DragUpdateDetails({
103
    this.sourceTimeStamp,
104 105 106
    this.delta: Offset.zero,
    this.primaryDelta,
    @required this.globalPosition
107 108 109 110
  }) : assert(delta != null),
       assert(primaryDelta == null
           || (primaryDelta == delta.dx && delta.dy == 0.0)
           || (primaryDelta == delta.dy && delta.dx == 0.0));
111

112 113 114 115 116 117
  /// Recorded timestamp of the source pointer event that triggered the drag
  /// event.
  ///
  /// Could be null if triggered from proxied events such as accessibility.
  final Duration sourceTimeStamp;

118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169
  /// The amount the pointer has moved since the previous update.
  ///
  /// If the [GestureDragUpdateCallback] is for a one-dimensional drag (e.g.,
  /// a horizontal or vertical drag), then this offset contains only the delta
  /// in that direction (i.e., the coordinate in the other direction is zero).
  ///
  /// Defaults to zero if not specified in the constructor.
  final Offset delta;

  /// The amount the pointer has moved along the primary axis since the previous
  /// update.
  ///
  /// If the [GestureDragUpdateCallback] is for a one-dimensional drag (e.g.,
  /// a horizontal or vertical drag), then this value contains the component of
  /// [delta] along the primary axis (e.g., horizontal or vertical,
  /// respectively). Otherwise, if the [GestureDragUpdateCallback] is for a
  /// two-dimensional drag (e.g., a pan), then this value is null.
  ///
  /// Defaults to null if not specified in the constructor.
  final double primaryDelta;

  /// The pointer's global position when it triggered this update.
  final Offset globalPosition;

  @override
  String toString() => '$runtimeType($delta)';
}

/// Signature for when a pointer that is in contact with the screen and moving
/// has moved again.
///
/// The `details` object provides the position of the touch and the distance it
/// has travelled since the last update.
///
/// See [DragGestureRecognizer.onUpdate].
typedef void GestureDragUpdateCallback(DragUpdateDetails details);

/// Details object for callbacks that use [GestureDragEndCallback].
///
/// See also:
///
///  * [DragGestureRecognizer.onEnd], which uses [GestureDragEndCallback].
///  * [DragDownDetails], the details for [GestureDragDownCallback].
///  * [DragStartDetails], the details for [GestureDragStartCallback].
///  * [DragUpdateDetails], the details for [GestureDragUpdateCallback].
class DragEndDetails {
  /// Creates details for a [GestureDragEndCallback].
  ///
  /// The [velocity] argument must not be null.
  DragEndDetails({
    this.velocity: Velocity.zero,
    this.primaryVelocity,
170 171 172 173
  }) : assert(velocity != null),
       assert(primaryVelocity == null
           || primaryVelocity == velocity.pixelsPerSecond.dx
           || primaryVelocity == velocity.pixelsPerSecond.dy);
174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194

  /// The velocity the pointer was moving when it stopped contacting the screen.
  ///
  /// Defaults to zero if not specified in the constructor.
  final Velocity velocity;

  /// The velocity the pointer was moving along the primary axis when it stopped
  /// contacting the screen, in logical pixels per second.
  ///
  /// If the [GestureDragEndCallback] is for a one-dimensional drag (e.g., a
  /// horizontal or vertical drag), then this value contains the component of
  /// [velocity] along the primary axis (e.g., horizontal or vertical,
  /// respectively). Otherwise, if the [GestureDragEndCallback] is for a
  /// two-dimensional drag (e.g., a pan), then this value is null.
  ///
  /// Defaults to null if not specified in the constructor.
  final double primaryVelocity;

  @override
  String toString() => '$runtimeType($velocity)';
}