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

import 'dart:async';
import 'dart:math' as math;
import 'dart:ui' as ui;

import 'package:flutter/foundation.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/scheduler.dart' show timeDilation;
import 'package:flutter/widgets.dart';

import 'constants.dart';
import 'debug.dart';
import 'slider_theme.dart';
import 'theme.dart';

// Examples can assume:
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// RangeValues _rangeValues = const RangeValues(0.3, 0.7);
// RangeValues _dollarsRange = const RangeValues(50, 100);
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// void setState(VoidCallback fn) { }

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/// [RangeSlider] uses this callback to paint the value indicator on the overlay.
/// Since the value indicator is painted on the Overlay; this method paints the
/// value indicator in a [RenderBox] that appears in the [Overlay].
typedef PaintRangeValueIndicator = void Function(PaintingContext context, Offset offset);

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/// A Material Design range slider.
///
/// Used to select a range from a range of values.
///
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/// {@youtube 560 315 https://www.youtube.com/watch?v=ufb4gIPDmEs}
///
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/// {@tool dartpad}
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/// ![A range slider widget, consisting of 5 divisions and showing the default
/// value indicator.](https://flutter.github.io/assets-for-api-docs/assets/material/range_slider.png)
///
/// This range values are in intervals of 20 because the Range Slider has 5
/// divisions, from 0 to 100. This means are values are split between 0, 20, 40,
/// 60, 80, and 100. The range values are initialized with 40 and 80 in this demo.
///
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/// ** See code in examples/api/lib/material/range_slider/range_slider.0.dart **
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/// {@end-tool}
///
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/// A range slider can be used to select from either a continuous or a discrete
/// set of values. The default is to use a continuous range of values from [min]
/// to [max]. To use discrete values, use a non-null value for [divisions], which
/// indicates the number of discrete intervals. For example, if [min] is 0.0 and
/// [max] is 50.0 and [divisions] is 5, then the slider can take on the
/// discrete values 0.0, 10.0, 20.0, 30.0, 40.0, and 50.0.
///
/// The terms for the parts of a slider are:
///
///  * The "thumbs", which are the shapes that slide horizontally when the user
///    drags them to change the selected range.
///  * The "track", which is the horizontal line that the thumbs can be dragged
///    along.
///  * The "tick marks", which mark the discrete values of a discrete slider.
///  * The "overlay", which is a highlight that's drawn over a thumb in response
///    to a user tap-down gesture.
///  * The "value indicators", which are the shapes that pop up when the user
///    is dragging a thumb to show the value being selected.
///  * The "active" segment of the slider is the segment between the two thumbs.
///  * The "inactive" slider segments are the two track intervals outside of the
///    slider's thumbs.
///
/// The range slider will be disabled if [onChanged] is null or if the range
/// given by [min]..[max] is empty (i.e. if [min] is equal to [max]).
///
/// The range slider widget itself does not maintain any state. Instead, when
/// the state of the slider changes, the widget calls the [onChanged] callback.
/// Most widgets that use a range slider will listen for the [onChanged] callback
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/// and rebuild the slider with new [values] to update the visual appearance of
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/// the slider. To know when the value starts to change, or when it is done
/// changing, set the optional callbacks [onChangeStart] and/or [onChangeEnd].
///
/// By default, a slider will be as wide as possible, centered vertically. When
/// given unbounded constraints, it will attempt to make the track 144 pixels
/// wide (including margins on each side) and will shrink-wrap vertically.
///
/// Requires one of its ancestors to be a [Material] widget. This is typically
/// provided by a [Scaffold] widget.
///
/// Requires one of its ancestors to be a [MediaQuery] widget. Typically, a
/// [MediaQuery] widget is introduced by the [MaterialApp] or [WidgetsApp]
/// widget at the top of your application widget tree.
///
/// To determine how it should be displayed (e.g. colors, thumb shape, etc.),
/// a slider uses the [SliderThemeData] available from either a [SliderTheme]
/// widget, or the [ThemeData.sliderTheme] inside a [Theme] widget above it in
/// the widget tree. You can also override some of the colors with the
/// [activeColor] and [inactiveColor] properties, although more fine-grained
/// control of the colors, and other visual properties is achieved using a
/// [SliderThemeData].
///
/// See also:
///
///  * [SliderTheme] and [SliderThemeData] for information about controlling
///    the visual appearance of the slider.
///  * [Slider], for a single-valued slider.
///  * [Radio], for selecting among a set of explicit values.
///  * [Checkbox] and [Switch], for toggling a particular value on or off.
///  * <https://material.io/design/components/sliders.html>
///  * [MediaQuery], from which the text scale factor is obtained.
class RangeSlider extends StatefulWidget {
  /// Creates a Material Design range slider.
  ///
  /// The range slider widget itself does not maintain any state. Instead, when
  /// the state of the slider changes, the widget calls the [onChanged] callback.
  /// Most widgets that use a range slider will listen for the [onChanged] callback
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  /// and rebuild the slider with new [values] to update the visual appearance of
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  /// the slider. To know when the value starts to change, or when it is done
  /// changing, set the optional callbacks [onChangeStart] and/or [onChangeEnd].
  ///
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  /// * [values], which determines currently selected values for this range
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  ///   slider.
  /// * [onChanged], which is called while the user is selecting a new value for
  ///   the range slider.
  /// * [onChangeStart], which is called when the user starts to select a new
  ///   value for the range slider.
  /// * [onChangeEnd], which is called when the user is done selecting a new
  ///   value for the range slider.
  ///
  /// You can override some of the colors with the [activeColor] and
  /// [inactiveColor] properties, although more fine-grained control of the
  /// appearance is achieved using a [SliderThemeData].
  ///
  /// The [values], [min], [max] must not be null. The [min] must be less than
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  /// or equal to the [max]. [values].start must be less than or equal to
  /// [values].end. [values].start and [values].end must be greater than or
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  /// equal to the [min] and less than or equal to the [max]. The [divisions]
  /// must be null or greater than 0.
  RangeSlider({
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    super.key,
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    required this.values,
    required this.onChanged,
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    this.onChangeStart,
    this.onChangeEnd,
    this.min = 0.0,
    this.max = 1.0,
    this.divisions,
    this.labels,
    this.activeColor,
    this.inactiveColor,
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    this.semanticFormatterCallback,
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  }) : assert(values != null),
       assert(min != null),
       assert(max != null),
       assert(min <= max),
       assert(values.start <= values.end),
       assert(values.start >= min && values.start <= max),
       assert(values.end >= min && values.end <= max),
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       assert(divisions == null || divisions > 0);
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  /// The currently selected values for this range slider.
  ///
  /// The slider's thumbs are drawn at horizontal positions that corresponds to
  /// these values.
  final RangeValues values;

  /// Called when the user is selecting a new value for the slider by dragging.
  ///
  /// The slider passes the new values to the callback but does not actually
  /// change state until the parent widget rebuilds the slider with the new
  /// values.
  ///
  /// If null, the slider will be displayed as disabled.
  ///
  /// The callback provided to [onChanged] should update the state of the parent
  /// [StatefulWidget] using the [State.setState] method, so that the parent
  /// gets rebuilt; for example:
  ///
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  /// {@tool snippet}
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  ///
  /// ```dart
  /// RangeSlider(
  ///   values: _rangeValues,
  ///   min: 1.0,
  ///   max: 10.0,
  ///   onChanged: (RangeValues newValues) {
  ///     setState(() {
  ///       _rangeValues = newValues;
  ///     });
  ///   },
  /// )
  /// ```
  /// {@end-tool}
  ///
  /// See also:
  ///
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  ///  * [onChangeStart], which is called when the user starts changing the
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  ///    values.
  ///  * [onChangeEnd], which is called when the user stops changing the values.
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  final ValueChanged<RangeValues>? onChanged;
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  /// Called when the user starts selecting new values for the slider.
  ///
  /// This callback shouldn't be used to update the slider [values] (use
  /// [onChanged] for that). Rather, it should be used to be notified when the
  /// user has started selecting a new value by starting a drag or with a tap.
  ///
  /// The values passed will be the last [values] that the slider had before the
  /// change began.
  ///
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  /// {@tool snippet}
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  ///
  /// ```dart
  /// RangeSlider(
  ///   values: _rangeValues,
  ///   min: 1.0,
  ///   max: 10.0,
  ///   onChanged: (RangeValues newValues) {
  ///     setState(() {
  ///       _rangeValues = newValues;
  ///     });
  ///   },
  ///   onChangeStart: (RangeValues startValues) {
  ///     print('Started change at $startValues');
  ///   },
  /// )
  /// ```
  /// {@end-tool}
  ///
  /// See also:
  ///
  ///  * [onChangeEnd] for a callback that is called when the value change is
  ///    complete.
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  final ValueChanged<RangeValues>? onChangeStart;
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  /// Called when the user is done selecting new values for the slider.
  ///
  /// This differs from [onChanged] because it is only called once at the end
  /// of the interaction, while [onChanged] is called as the value is getting
  /// updated within the interaction.
  ///
  /// This callback shouldn't be used to update the slider [values] (use
  /// [onChanged] for that). Rather, it should be used to know when the user has
  /// completed selecting a new [values] by ending a drag or a click.
  ///
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  /// {@tool snippet}
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  ///
  /// ```dart
  /// RangeSlider(
  ///   values: _rangeValues,
  ///   min: 1.0,
  ///   max: 10.0,
  ///   onChanged: (RangeValues newValues) {
  ///     setState(() {
  ///       _rangeValues = newValues;
  ///     });
  ///   },
  ///   onChangeEnd: (RangeValues endValues) {
  ///     print('Ended change at $endValues');
  ///   },
  /// )
  /// ```
  /// {@end-tool}
  ///
  /// See also:
  ///
  ///  * [onChangeStart] for a callback that is called when a value change
  ///    begins.
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  final ValueChanged<RangeValues>? onChangeEnd;
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  /// The minimum value the user can select.
  ///
  /// Defaults to 0.0. Must be less than or equal to [max].
  ///
  /// If the [max] is equal to the [min], then the slider is disabled.
  final double min;

  /// The maximum value the user can select.
  ///
  /// Defaults to 1.0. Must be greater than or equal to [min].
  ///
  /// If the [max] is equal to the [min], then the slider is disabled.
  final double max;

  /// The number of discrete divisions.
  ///
  /// Typically used with [labels] to show the current discrete values.
  ///
  /// If null, the slider is continuous.
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  final int? divisions;
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  /// Labels to show as text in the [SliderThemeData.rangeValueIndicatorShape]
  /// when the slider is active and [SliderThemeData.showValueIndicator]
  /// is satisfied.
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  ///
  /// There are two labels: one for the start thumb and one for the end thumb.
  ///
  /// Each label is rendered using the active [ThemeData]'s
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  /// [TextTheme.bodyLarge] text style, with the theme data's
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  /// [ColorScheme.onPrimary] color. The label's text style can be overridden
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  /// with [SliderThemeData.valueIndicatorTextStyle].
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  ///
  /// If null, then the value indicator will not be displayed.
  ///
  /// See also:
  ///
  ///  * [RangeSliderValueIndicatorShape] for how to create a custom value
  ///    indicator shape.
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  final RangeLabels? labels;
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  /// The color of the track's active segment, i.e. the span of track between
  /// the thumbs.
  ///
  /// Defaults to [ColorScheme.primary].
  ///
  /// Using a [SliderTheme] gives more fine-grained control over the
  /// appearance of various components of the slider.
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  final Color? activeColor;
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  /// The color of the track's inactive segments, i.e. the span of tracks
  /// between the min and the start thumb, and the end thumb and the max.
  ///
  /// Defaults to [ColorScheme.primary] with 24% opacity.
  ///
  /// Using a [SliderTheme] gives more fine-grained control over the
  /// appearance of various components of the slider.
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  final Color? inactiveColor;
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  /// The callback used to create a semantic value from the slider's values.
  ///
  /// Defaults to formatting values as a percentage.
  ///
  /// This is used by accessibility frameworks like TalkBack on Android to
  /// inform users what the currently selected value is with more context.
  ///
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  /// {@tool snippet}
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  ///
  /// In the example below, a slider for currency values is configured to
  /// announce a value with a currency label.
  ///
  /// ```dart
  /// RangeSlider(
  ///   values: _dollarsRange,
  ///   min: 20.0,
  ///   max: 330.0,
  ///   onChanged: (RangeValues newValues) {
  ///     setState(() {
  ///       _dollarsRange = newValues;
  ///     });
  ///   },
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  ///   semanticFormatterCallback: (double newValue) {
  ///     return '${newValue.round()} dollars';
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  ///   }
  ///  )
  /// ```
  /// {@end-tool}
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  final SemanticFormatterCallback? semanticFormatterCallback;
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  // Touch width for the tap boundary of the slider thumbs.
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  static const double _minTouchTargetWidth = kMinInteractiveDimension;
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  @override
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  State<RangeSlider> createState() => _RangeSliderState();
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  @override
  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
    super.debugFillProperties(properties);
    properties.add(DoubleProperty('valueStart', values.start));
    properties.add(DoubleProperty('valueEnd', values.end));
    properties.add(ObjectFlagProperty<ValueChanged<RangeValues>>('onChanged', onChanged, ifNull: 'disabled'));
    properties.add(ObjectFlagProperty<ValueChanged<RangeValues>>.has('onChangeStart', onChangeStart));
    properties.add(ObjectFlagProperty<ValueChanged<RangeValues>>.has('onChangeEnd', onChangeEnd));
    properties.add(DoubleProperty('min', min));
    properties.add(DoubleProperty('max', max));
    properties.add(IntProperty('divisions', divisions));
    properties.add(StringProperty('labelStart', labels?.start));
    properties.add(StringProperty('labelEnd', labels?.end));
    properties.add(ColorProperty('activeColor', activeColor));
    properties.add(ColorProperty('inactiveColor', inactiveColor));
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    properties.add(ObjectFlagProperty<ValueChanged<double>>.has('semanticFormatterCallback', semanticFormatterCallback));
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  }
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}

class _RangeSliderState extends State<RangeSlider> with TickerProviderStateMixin {
  static const Duration enableAnimationDuration = Duration(milliseconds: 75);
  static const Duration valueIndicatorAnimationDuration = Duration(milliseconds: 100);

  // Animation controller that is run when the overlay (a.k.a radial reaction)
  // changes visibility in response to user interaction.
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  late AnimationController overlayController;
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  // Animation controller that is run when the value indicators change visibility.
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  late AnimationController valueIndicatorController;
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  // Animation controller that is run when enabling/disabling the slider.
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  late AnimationController enableController;
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  // Animation controllers that are run when transitioning between one value
  // and the next on a discrete slider.
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  late AnimationController startPositionController;
  late AnimationController endPositionController;
  Timer? interactionTimer;
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  // Value Indicator paint Animation that appears on the Overlay.
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  PaintRangeValueIndicator? paintTopValueIndicator;
  PaintRangeValueIndicator? paintBottomValueIndicator;
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  @override
  void initState() {
    super.initState();
    overlayController = AnimationController(
      duration: kRadialReactionDuration,
      vsync: this,
    );
    valueIndicatorController = AnimationController(
      duration: valueIndicatorAnimationDuration,
      vsync: this,
    );
    enableController = AnimationController(
      duration: enableAnimationDuration,
      vsync: this,
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      value: widget.onChanged != null ? 1.0 : 0.0,
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    );
    startPositionController = AnimationController(
      duration: Duration.zero,
      vsync: this,
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      value: _unlerp(widget.values.start),
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    );
    endPositionController = AnimationController(
      duration: Duration.zero,
      vsync: this,
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      value: _unlerp(widget.values.end),
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    );
  }

  @override
  void didUpdateWidget(RangeSlider oldWidget) {
    super.didUpdateWidget(oldWidget);
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    if (oldWidget.onChanged == widget.onChanged) {
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      return;
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    }
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    final bool wasEnabled = oldWidget.onChanged != null;
    final bool isEnabled = widget.onChanged != null;
    if (wasEnabled != isEnabled) {
      if (isEnabled) {
        enableController.forward();
      } else {
        enableController.reverse();
      }
    }
  }

  @override
  void dispose() {
    interactionTimer?.cancel();
    overlayController.dispose();
    valueIndicatorController.dispose();
    enableController.dispose();
    startPositionController.dispose();
    endPositionController.dispose();
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    if (overlayEntry != null) {
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      overlayEntry!.remove();
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      overlayEntry = null;
    }
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    super.dispose();
  }

  void _handleChanged(RangeValues values) {
    assert(widget.onChanged != null);
    final RangeValues lerpValues = _lerpRangeValues(values);
    if (lerpValues != widget.values) {
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      widget.onChanged!(lerpValues);
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    }
  }

  void _handleDragStart(RangeValues values) {
    assert(widget.onChangeStart != null);
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    widget.onChangeStart!(_lerpRangeValues(values));
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  }

  void _handleDragEnd(RangeValues values) {
    assert(widget.onChangeEnd != null);
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    widget.onChangeEnd!(_lerpRangeValues(values));
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  }

  // Returns a number between min and max, proportional to value, which must
  // be between 0.0 and 1.0.
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  double _lerp(double value) => ui.lerpDouble(widget.min, widget.max, value)!;
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  // Returns a new range value with the start and end lerped.
  RangeValues _lerpRangeValues(RangeValues values) {
    return RangeValues(_lerp(values.start), _lerp(values.end));
  }

  // Returns a number between 0.0 and 1.0, given a value between min and max.
  double _unlerp(double value) {
    assert(value <= widget.max);
    assert(value >= widget.min);
    return widget.max > widget.min ? (value - widget.min) / (widget.max - widget.min) : 0.0;
  }

  // Returns a new range value with the start and end unlerped.
  RangeValues _unlerpRangeValues(RangeValues values) {
    return RangeValues(_unlerp(values.start), _unlerp(values.end));
  }

  // Finds closest thumb. If the thumbs are close to each other, no thumb is
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  // immediately selected while the drag displacement is zero. If the first
  // non-zero displacement is negative, then the left thumb is selected, and if its
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  // positive, then the right thumb is selected.
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  Thumb? _defaultRangeThumbSelector(
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    TextDirection textDirection,
    RangeValues values,
    double tapValue,
    Size thumbSize,
    Size trackSize,
    double dx, // The horizontal delta or displacement of the drag update.
  ) {
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    final double touchRadius = math.max(thumbSize.width, RangeSlider._minTouchTargetWidth) / 2;
    final bool inStartTouchTarget = (tapValue - values.start).abs() * trackSize.width < touchRadius;
    final bool inEndTouchTarget = (tapValue - values.end).abs() * trackSize.width < touchRadius;

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    // Use dx if the thumb touch targets overlap. If dx is 0 and the drag
    // position is in both touch targets, no thumb is selected because it is
    // ambiguous to which thumb should be selected. If the dx is non-zero, the
    // thumb selection is determined by the direction of the dx. The left thumb
    // is chosen for negative dx, and the right thumb is chosen for positive dx.
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    if (inStartTouchTarget && inEndTouchTarget) {
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      final bool towardsStart;
      final bool towardsEnd;
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      switch (textDirection) {
        case TextDirection.ltr:
          towardsStart = dx < 0;
          towardsEnd = dx > 0;
          break;
        case TextDirection.rtl:
          towardsStart = dx > 0;
          towardsEnd = dx < 0;
          break;
      }
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      if (towardsStart) {
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        return Thumb.start;
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      }
      if (towardsEnd) {
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        return Thumb.end;
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      }
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    } else {
      // Snap position on the track if its in the inactive range.
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      if (tapValue < values.start || inStartTouchTarget) {
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        return Thumb.start;
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      }
      if (tapValue > values.end || inEndTouchTarget) {
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        return Thumb.end;
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      }
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    }
    return null;
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  }
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  @override
  Widget build(BuildContext context) {
    assert(debugCheckHasMaterial(context));
    assert(debugCheckHasMediaQuery(context));

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    final ThemeData theme = Theme.of(context);
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    SliderThemeData sliderTheme = SliderTheme.of(context);

    // If the widget has active or inactive colors specified, then we plug them
    // in to the slider theme as best we can. If the developer wants more
    // control than that, then they need to use a SliderTheme. The default
    // colors come from the ThemeData.colorScheme. These colors, along with
    // the default shapes and text styles are aligned to the Material
    // Guidelines.
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    const double defaultTrackHeight = 4;
    const RangeSliderTrackShape defaultTrackShape = RoundedRectRangeSliderTrackShape();
    const RangeSliderTickMarkShape defaultTickMarkShape = RoundRangeSliderTickMarkShape();
    const SliderComponentShape defaultOverlayShape = RoundSliderOverlayShape();
    const RangeSliderThumbShape defaultThumbShape = RoundRangeSliderThumbShape();
    const RangeSliderValueIndicatorShape defaultValueIndicatorShape = RectangularRangeSliderValueIndicatorShape();
    const ShowValueIndicator defaultShowValueIndicator = ShowValueIndicator.onlyForDiscrete;
    const double defaultMinThumbSeparation = 8;
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    // The value indicator's color is not the same as the thumb and active track
    // (which can be defined by activeColor) if the
    // RectangularSliderValueIndicatorShape is used. In all other cases, the
    // value indicator is assumed to be the same as the active color.
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    final RangeSliderValueIndicatorShape valueIndicatorShape = sliderTheme.rangeValueIndicatorShape ?? defaultValueIndicatorShape;
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    final Color valueIndicatorColor;
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    if (valueIndicatorShape is RectangularRangeSliderValueIndicatorShape) {
      valueIndicatorColor = sliderTheme.valueIndicatorColor ?? Color.alphaBlend(theme.colorScheme.onSurface.withOpacity(0.60), theme.colorScheme.surface.withOpacity(0.90));
    } else {
      valueIndicatorColor = widget.activeColor ?? sliderTheme.valueIndicatorColor ?? theme.colorScheme.primary;
    }

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    sliderTheme = sliderTheme.copyWith(
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      trackHeight: sliderTheme.trackHeight ?? defaultTrackHeight,
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      activeTrackColor: widget.activeColor ?? sliderTheme.activeTrackColor ?? theme.colorScheme.primary,
      inactiveTrackColor: widget.inactiveColor ?? sliderTheme.inactiveTrackColor ?? theme.colorScheme.primary.withOpacity(0.24),
      disabledActiveTrackColor: sliderTheme.disabledActiveTrackColor ?? theme.colorScheme.onSurface.withOpacity(0.32),
      disabledInactiveTrackColor: sliderTheme.disabledInactiveTrackColor ?? theme.colorScheme.onSurface.withOpacity(0.12),
      activeTickMarkColor: widget.inactiveColor ?? sliderTheme.activeTickMarkColor ?? theme.colorScheme.onPrimary.withOpacity(0.54),
      inactiveTickMarkColor: widget.activeColor ?? sliderTheme.inactiveTickMarkColor ?? theme.colorScheme.primary.withOpacity(0.54),
      disabledActiveTickMarkColor: sliderTheme.disabledActiveTickMarkColor ?? theme.colorScheme.onPrimary.withOpacity(0.12),
      disabledInactiveTickMarkColor: sliderTheme.disabledInactiveTickMarkColor ?? theme.colorScheme.onSurface.withOpacity(0.12),
      thumbColor: widget.activeColor ?? sliderTheme.thumbColor ?? theme.colorScheme.primary,
      overlappingShapeStrokeColor: sliderTheme.overlappingShapeStrokeColor ?? theme.colorScheme.surface,
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      disabledThumbColor: sliderTheme.disabledThumbColor ?? Color.alphaBlend(theme.colorScheme.onSurface.withOpacity(.38), theme.colorScheme.surface),
604
      overlayColor: widget.activeColor?.withOpacity(0.12) ?? sliderTheme.overlayColor ?? theme.colorScheme.primary.withOpacity(0.12),
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      valueIndicatorColor: valueIndicatorColor,
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      rangeTrackShape: sliderTheme.rangeTrackShape ?? defaultTrackShape,
      rangeTickMarkShape: sliderTheme.rangeTickMarkShape ?? defaultTickMarkShape,
      rangeThumbShape: sliderTheme.rangeThumbShape ?? defaultThumbShape,
      overlayShape: sliderTheme.overlayShape ?? defaultOverlayShape,
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      rangeValueIndicatorShape: valueIndicatorShape,
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      showValueIndicator: sliderTheme.showValueIndicator ?? defaultShowValueIndicator,
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      valueIndicatorTextStyle: sliderTheme.valueIndicatorTextStyle ?? theme.textTheme.bodyLarge!.copyWith(
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        color: theme.colorScheme.onPrimary,
      ),
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      minThumbSeparation: sliderTheme.minThumbSeparation ?? defaultMinThumbSeparation,
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      thumbSelector: sliderTheme.thumbSelector ?? _defaultRangeThumbSelector,
    );

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    // This size is used as the max bounds for the painting of the value
    // indicators. It must be kept in sync with the function with the same name
    // in slider.dart.
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    Size screenSize() => MediaQuery.of(context).size;
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    return CompositedTransformTarget(
      link: _layerLink,
      child: _RangeSliderRenderObjectWidget(
        values: _unlerpRangeValues(widget.values),
        divisions: widget.divisions,
        labels: widget.labels,
        sliderTheme: sliderTheme,
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        textScaleFactor: MediaQuery.of(context).textScaleFactor,
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        screenSize: screenSize(),
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        onChanged: (widget.onChanged != null) && (widget.max > widget.min) ? _handleChanged : null,
        onChangeStart: widget.onChangeStart != null ? _handleDragStart : null,
        onChangeEnd: widget.onChangeEnd != null ? _handleDragEnd : null,
        state: this,
        semanticFormatterCallback: widget.semanticFormatterCallback,
      ),
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    );
  }
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  final LayerLink _layerLink = LayerLink();

644
  OverlayEntry? overlayEntry;
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  void showValueIndicator() {
    if (overlayEntry == null) {
      overlayEntry = OverlayEntry(
        builder: (BuildContext context) {
          return CompositedTransformFollower(
            link: _layerLink,
            child: _ValueIndicatorRenderObjectWidget(
              state: this,
            ),
          );
        },
      );
658
      Overlay.of(context, debugRequiredFor: widget).insert(overlayEntry!);
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    }
  }
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}

class _RangeSliderRenderObjectWidget extends LeafRenderObjectWidget {
  const _RangeSliderRenderObjectWidget({
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    required this.values,
    required this.divisions,
    required this.labels,
    required this.sliderTheme,
    required this.textScaleFactor,
    required this.screenSize,
    required this.onChanged,
    required this.onChangeStart,
    required this.onChangeEnd,
    required this.state,
    required this.semanticFormatterCallback,
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  });
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  final RangeValues values;
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  final int? divisions;
  final RangeLabels? labels;
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  final SliderThemeData sliderTheme;
  final double textScaleFactor;
683
  final Size screenSize;
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  final ValueChanged<RangeValues>? onChanged;
  final ValueChanged<RangeValues>? onChangeStart;
  final ValueChanged<RangeValues>? onChangeEnd;
  final SemanticFormatterCallback? semanticFormatterCallback;
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  final _RangeSliderState state;

  @override
  _RenderRangeSlider createRenderObject(BuildContext context) {
    return _RenderRangeSlider(
      values: values,
      divisions: divisions,
      labels: labels,
      sliderTheme: sliderTheme,
      theme: Theme.of(context),
      textScaleFactor: textScaleFactor,
699
      screenSize: screenSize,
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      onChanged: onChanged,
      onChangeStart: onChangeStart,
      onChangeEnd: onChangeEnd,
      state: state,
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      textDirection: Directionality.of(context),
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      semanticFormatterCallback: semanticFormatterCallback,
706
      platform: Theme.of(context).platform,
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      gestureSettings: MediaQuery.of(context).gestureSettings,
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    );
  }

  @override
  void updateRenderObject(BuildContext context, _RenderRangeSlider renderObject) {
    renderObject
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      // We should update the `divisions` ahead of `values`, because the `values`
      // setter dependent on the `divisions`.
716
      ..divisions = divisions
717
      ..values = values
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      ..labels = labels
      ..sliderTheme = sliderTheme
      ..theme = Theme.of(context)
      ..textScaleFactor = textScaleFactor
722
      ..screenSize = screenSize
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      ..onChanged = onChanged
      ..onChangeStart = onChangeStart
      ..onChangeEnd = onChangeEnd
726
      ..textDirection = Directionality.of(context)
727
      ..semanticFormatterCallback = semanticFormatterCallback
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      ..platform = Theme.of(context).platform
      ..gestureSettings = MediaQuery.of(context).gestureSettings;
730 731 732
  }
}

733
class _RenderRangeSlider extends RenderBox with RelayoutWhenSystemFontsChangeMixin {
734
  _RenderRangeSlider({
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    required RangeValues values,
    required int? divisions,
    required RangeLabels? labels,
    required SliderThemeData sliderTheme,
    required ThemeData? theme,
    required double textScaleFactor,
    required Size screenSize,
    required TargetPlatform platform,
    required ValueChanged<RangeValues>? onChanged,
    required SemanticFormatterCallback? semanticFormatterCallback,
    required this.onChangeStart,
    required this.onChangeEnd,
    required _RangeSliderState state,
    required TextDirection textDirection,
749
    required DeviceGestureSettings gestureSettings,
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  })  : assert(values != null),
        assert(values.start >= 0.0 && values.start <= 1.0),
        assert(values.end >= 0.0 && values.end <= 1.0),
        assert(state != null),
        assert(textDirection != null),
        _platform = platform,
        _semanticFormatterCallback = semanticFormatterCallback,
        _labels = labels,
        _values = values,
        _divisions = divisions,
        _sliderTheme = sliderTheme,
        _theme = theme,
        _textScaleFactor = textScaleFactor,
763
        _screenSize = screenSize,
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        _onChanged = onChanged,
        _state = state,
766
        _textDirection = textDirection {
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    _updateLabelPainters();
    final GestureArenaTeam team = GestureArenaTeam();
    _drag = HorizontalDragGestureRecognizer()
      ..team = team
      ..onStart = _handleDragStart
      ..onUpdate = _handleDragUpdate
      ..onEnd = _handleDragEnd
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      ..onCancel = _handleDragCancel
      ..gestureSettings = gestureSettings;
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    _tap = TapGestureRecognizer()
      ..team = team
      ..onTapDown = _handleTapDown
      ..onTapUp = _handleTapUp
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      ..onTapCancel = _handleTapCancel
      ..gestureSettings = gestureSettings;
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    _overlayAnimation = CurvedAnimation(
      parent: _state.overlayController,
      curve: Curves.fastOutSlowIn,
    );
    _valueIndicatorAnimation = CurvedAnimation(
      parent: _state.valueIndicatorController,
      curve: Curves.fastOutSlowIn,
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    )..addStatusListener((AnimationStatus status) {
      if (status == AnimationStatus.dismissed && _state.overlayEntry != null) {
791
        _state.overlayEntry!.remove();
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        _state.overlayEntry = null;
      }
    });
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    _enableAnimation = CurvedAnimation(
      parent: _state.enableController,
      curve: Curves.easeInOut,
    );
  }

  // Keep track of the last selected thumb so they can be drawn in the
  // right order.
803
  Thumb? _lastThumbSelection;
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  static const Duration _positionAnimationDuration = Duration(milliseconds: 75);

  // This value is the touch target, 48, multiplied by 3.
  static const double _minPreferredTrackWidth = 144.0;

  // Compute the largest width and height needed to paint the slider shapes,
  // other than the track shape. It is assumed that these shapes are vertically
  // centered on the track.
  double get _maxSliderPartWidth => _sliderPartSizes.map((Size size) => size.width).reduce(math.max);
  double get _maxSliderPartHeight => _sliderPartSizes.map((Size size) => size.height).reduce(math.max);
  List<Size> get _sliderPartSizes => <Size>[
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    _sliderTheme.overlayShape!.getPreferredSize(isEnabled, isDiscrete),
    _sliderTheme.rangeThumbShape!.getPreferredSize(isEnabled, isDiscrete),
    _sliderTheme.rangeTickMarkShape!.getPreferredSize(isEnabled: isEnabled, sliderTheme: sliderTheme),
819
  ];
820
  double? get _minPreferredTrackHeight => _sliderTheme.trackHeight;
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  // This rect is used in gesture calculations, where the gesture coordinates
  // are relative to the sliders origin. Therefore, the offset is passed as
  // (0,0).
825
  Rect get _trackRect => _sliderTheme.rangeTrackShape!.getPreferredRect(
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    parentBox: this,
    sliderTheme: _sliderTheme,
    isDiscrete: false,
  );

  static const Duration _minimumInteractionTime = Duration(milliseconds: 500);

833
  final _RangeSliderState _state;
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  late Animation<double> _overlayAnimation;
  late Animation<double> _valueIndicatorAnimation;
  late Animation<double> _enableAnimation;
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  final TextPainter _startLabelPainter = TextPainter();
  final TextPainter _endLabelPainter = TextPainter();
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  late HorizontalDragGestureRecognizer _drag;
  late TapGestureRecognizer _tap;
841
  bool _active = false;
842
  late RangeValues _newValues;
843 844 845

  bool get isEnabled => onChanged != null;

846
  bool get isDiscrete => divisions != null && divisions! > 0;
847

848
  double get _minThumbSeparationValue => isDiscrete ? 0 : sliderTheme.minThumbSeparation! / _trackRect.width;
849

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  RangeValues get values => _values;
  RangeValues _values;
  set values(RangeValues newValues) {
    assert(newValues != null);
    assert(newValues.start != null && newValues.start >= 0.0 && newValues.start <= 1.0);
    assert(newValues.end != null && newValues.end >= 0.0 && newValues.end <= 1.0);
    assert(newValues.start <= newValues.end);
    final RangeValues convertedValues = isDiscrete ? _discretizeRangeValues(newValues) : newValues;
    if (convertedValues == _values) {
      return;
    }
    _values = convertedValues;
    if (isDiscrete) {
      // Reset the duration to match the distance that we're traveling, so that
      // whatever the distance, we still do it in _positionAnimationDuration,
      // and if we get re-targeted in the middle, it still takes that long to
      // get to the new location.
      final double startDistance = (_values.start -  _state.startPositionController.value).abs();
      _state.startPositionController.duration = startDistance != 0.0 ? _positionAnimationDuration * (1.0 / startDistance) : Duration.zero;
      _state.startPositionController.animateTo(_values.start, curve: Curves.easeInOut);
      final double endDistance = (_values.end -  _state.endPositionController.value).abs();
      _state.endPositionController.duration = endDistance != 0.0 ? _positionAnimationDuration * (1.0 / endDistance) : Duration.zero;
      _state.endPositionController.animateTo(_values.end, curve: Curves.easeInOut);
    } else {
      _state.startPositionController.value = convertedValues.start;
      _state.endPositionController.value = convertedValues.end;
    }
    markNeedsSemanticsUpdate();
  }

  TargetPlatform _platform;
  TargetPlatform get platform => _platform;
  set platform(TargetPlatform value) {
883
    if (_platform == value) {
884
      return;
885
    }
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    _platform = value;
    markNeedsSemanticsUpdate();
  }

890 891 892 893 894 895
  DeviceGestureSettings? get gestureSettings => _drag.gestureSettings;
  set gestureSettings(DeviceGestureSettings? gestureSettings) {
    _drag.gestureSettings = gestureSettings;
    _tap.gestureSettings = gestureSettings;
  }

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  SemanticFormatterCallback? _semanticFormatterCallback;
  SemanticFormatterCallback? get semanticFormatterCallback => _semanticFormatterCallback;
  set semanticFormatterCallback(SemanticFormatterCallback? value) {
899
    if (_semanticFormatterCallback == value) {
900
      return;
901
    }
902 903 904 905
    _semanticFormatterCallback = value;
    markNeedsSemanticsUpdate();
  }

906 907 908
  int? get divisions => _divisions;
  int? _divisions;
  set divisions(int? value) {
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    if (value == _divisions) {
      return;
    }
    _divisions = value;
    markNeedsPaint();
  }

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  RangeLabels? get labels => _labels;
  RangeLabels? _labels;
  set labels(RangeLabels? labels) {
919
    if (labels == _labels) {
920
      return;
921
    }
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    _labels = labels;
    _updateLabelPainters();
  }

  SliderThemeData get sliderTheme => _sliderTheme;
  SliderThemeData _sliderTheme;
  set sliderTheme(SliderThemeData value) {
929
    if (value == _sliderTheme) {
930
      return;
931
    }
932 933 934 935
    _sliderTheme = value;
    markNeedsPaint();
  }

936 937 938
  ThemeData? get theme => _theme;
  ThemeData? _theme;
  set theme(ThemeData? value) {
939
    if (value == _theme) {
940
      return;
941
    }
942 943 944 945 946 947 948
    _theme = value;
    markNeedsPaint();
  }

  double get textScaleFactor => _textScaleFactor;
  double _textScaleFactor;
  set textScaleFactor(double value) {
949
    if (value == _textScaleFactor) {
950
      return;
951
    }
952 953 954 955
    _textScaleFactor = value;
    _updateLabelPainters();
  }

956 957 958
  Size get screenSize => _screenSize;
  Size _screenSize;
  set screenSize(Size value) {
959
    if (value == screenSize) {
960
      return;
961
    }
962 963 964 965
    _screenSize = value;
    markNeedsPaint();
  }

966 967 968
  ValueChanged<RangeValues>? get onChanged => _onChanged;
  ValueChanged<RangeValues>? _onChanged;
  set onChanged(ValueChanged<RangeValues>? value) {
969
    if (value == _onChanged) {
970
      return;
971
    }
972 973 974 975 976 977 978 979
    final bool wasEnabled = isEnabled;
    _onChanged = value;
    if (wasEnabled != isEnabled) {
      markNeedsPaint();
      markNeedsSemanticsUpdate();
    }
  }

980 981
  ValueChanged<RangeValues>? onChangeStart;
  ValueChanged<RangeValues>? onChangeEnd;
982 983 984 985 986

  TextDirection get textDirection => _textDirection;
  TextDirection _textDirection;
  set textDirection(TextDirection value) {
    assert(value != null);
987
    if (value == _textDirection) {
988
      return;
989
    }
990 991 992 993 994
    _textDirection = value;
    _updateLabelPainters();
  }

  bool get showValueIndicator {
995
    switch (_sliderTheme.showValueIndicator!) {
996
      case ShowValueIndicator.onlyForDiscrete:
997
        return isDiscrete;
998
      case ShowValueIndicator.onlyForContinuous:
999
        return !isDiscrete;
1000
      case ShowValueIndicator.always:
1001
        return true;
1002
      case ShowValueIndicator.never:
1003
        return false;
1004 1005 1006
    }
  }

1007
  Size get _thumbSize => _sliderTheme.rangeThumbShape!.getPreferredSize(isEnabled, isDiscrete);
1008 1009 1010 1011 1012 1013 1014 1015

  double get _adjustmentUnit {
    switch (_platform) {
      case TargetPlatform.iOS:
        // Matches iOS implementation of material slider.
        return 0.1;
      case TargetPlatform.android:
      case TargetPlatform.fuchsia:
1016 1017 1018
      case TargetPlatform.linux:
      case TargetPlatform.macOS:
      case TargetPlatform.windows:
1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029
        // Matches Android implementation of material slider.
        return 0.05;
    }
  }

  void _updateLabelPainters() {
    _updateLabelPainter(Thumb.start);
    _updateLabelPainter(Thumb.end);
  }

  void _updateLabelPainter(Thumb thumb) {
1030
    if (labels == null) {
1031
      return;
1032
    }
1033

1034 1035
    final String text;
    final TextPainter labelPainter;
1036 1037
    switch (thumb) {
      case Thumb.start:
1038
        text = labels!.start;
1039 1040 1041
        labelPainter = _startLabelPainter;
        break;
      case Thumb.end:
1042
        text = labels!.end;
1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064
        labelPainter = _endLabelPainter;
        break;
    }

    if (labels != null) {
      labelPainter
        ..text = TextSpan(
          style: _sliderTheme.valueIndicatorTextStyle,
          text: text,
        )
        ..textDirection = textDirection
        ..textScaleFactor = textScaleFactor
        ..layout();
    } else {
      labelPainter.text = null;
    }
    // Changing the textDirection can result in the layout changing, because the
    // bidi algorithm might line up the glyphs differently which can result in
    // different ligatures, different shapes, etc. So we always markNeedsLayout.
    markNeedsLayout();
  }

1065 1066 1067 1068 1069 1070 1071 1072
  @override
  void systemFontsDidChange() {
    super.systemFontsDidChange();
    _startLabelPainter.markNeedsLayout();
    _endLabelPainter.markNeedsLayout();
    _updateLabelPainters();
  }

1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092
  @override
  void attach(PipelineOwner owner) {
    super.attach(owner);
    _overlayAnimation.addListener(markNeedsPaint);
    _valueIndicatorAnimation.addListener(markNeedsPaint);
    _enableAnimation.addListener(markNeedsPaint);
    _state.startPositionController.addListener(markNeedsPaint);
    _state.endPositionController.addListener(markNeedsPaint);
  }

  @override
  void detach() {
    _overlayAnimation.removeListener(markNeedsPaint);
    _valueIndicatorAnimation.removeListener(markNeedsPaint);
    _enableAnimation.removeListener(markNeedsPaint);
    _state.startPositionController.removeListener(markNeedsPaint);
    _state.endPositionController.removeListener(markNeedsPaint);
    super.detach();
  }

1093 1094 1095 1096 1097 1098 1099
  @override
  void dispose() {
    _startLabelPainter.dispose();
    _endLabelPainter.dispose();
    super.dispose();
  }

1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114
  double _getValueFromVisualPosition(double visualPosition) {
    switch (textDirection) {
      case TextDirection.rtl:
        return 1.0 - visualPosition;
      case TextDirection.ltr:
        return visualPosition;
    }
  }

  double _getValueFromGlobalPosition(Offset globalPosition) {
    final double visualPosition = (globalToLocal(globalPosition).dx - _trackRect.left) / _trackRect.width;
    return _getValueFromVisualPosition(visualPosition);
  }

  double _discretize(double value) {
1115
    double result = clampDouble(value, 0.0, 1.0);
1116
    if (isDiscrete) {
1117
      result = (result * divisions!).round() / divisions!;
1118 1119 1120 1121 1122 1123 1124 1125 1126
    }
    return result;
  }

  RangeValues _discretizeRangeValues(RangeValues values) {
    return RangeValues(_discretize(values.start), _discretize(values.end));
  }

  void _startInteraction(Offset globalPosition) {
1127
    _state.showValueIndicator();
1128
    final double tapValue = clampDouble(_getValueFromGlobalPosition(globalPosition), 0.0, 1.0);
1129
    _lastThumbSelection = sliderTheme.thumbSelector!(textDirection, values, tapValue, _thumbSize, size, 0);
1130 1131 1132 1133 1134 1135 1136 1137

    if (_lastThumbSelection != null) {
      _active = true;
      // We supply the *current* values as the start locations, so that if we have
      // a tap, it consists of a call to onChangeStart with the previous value and
      // a call to onChangeEnd with the new value.
      final RangeValues currentValues = _discretizeRangeValues(values);
      if (_lastThumbSelection == Thumb.start) {
1138
        _newValues = RangeValues(tapValue, currentValues.end);
1139
      } else if (_lastThumbSelection == Thumb.end) {
1140
        _newValues = RangeValues(currentValues.start, tapValue);
1141
      }
1142
      _updateLabelPainter(_lastThumbSelection!);
1143

1144
      onChangeStart?.call(currentValues);
1145

1146
      onChanged!(_discretizeRangeValues(_newValues));
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      _state.overlayController.forward();
      if (showValueIndicator) {
        _state.valueIndicatorController.forward();
        _state.interactionTimer?.cancel();
        _state.interactionTimer =
          Timer(_minimumInteractionTime * timeDilation, () {
            _state.interactionTimer = null;
            if (!_active && _state.valueIndicatorController.status == AnimationStatus.completed) {
              _state.valueIndicatorController.reverse();
            }
          });
      }
    }
  }

  void _handleDragUpdate(DragUpdateDetails details) {
1164 1165 1166 1167
    if (!_state.mounted) {
      return;
    }

1168 1169
    final double dragValue = _getValueFromGlobalPosition(details.globalPosition);

1170 1171 1172 1173
    // If no selection has been made yet, test for thumb selection again now
    // that the value of dx can be non-zero. If this is the first selection of
    // the interaction, then onChangeStart must be called.
    bool shouldCallOnChangeStart = false;
1174
    if (_lastThumbSelection == null) {
1175
      _lastThumbSelection = sliderTheme.thumbSelector!(textDirection, values, dragValue, _thumbSize, size, details.delta.dx);
1176
      if (_lastThumbSelection != null) {
1177 1178
        shouldCallOnChangeStart = true;
        _active = true;
1179 1180 1181 1182 1183 1184 1185 1186 1187
        _state.overlayController.forward();
        if (showValueIndicator) {
          _state.valueIndicatorController.forward();
        }
      }
    }

    if (isEnabled && _lastThumbSelection != null) {
      final RangeValues currentValues = _discretizeRangeValues(values);
1188
      if (onChangeStart != null && shouldCallOnChangeStart) {
1189
        onChangeStart!(currentValues);
1190
      }
1191 1192 1193
      final double currentDragValue = _discretize(dragValue);

      if (_lastThumbSelection == Thumb.start) {
1194
        _newValues = RangeValues(math.min(currentDragValue, currentValues.end - _minThumbSeparationValue), currentValues.end);
1195
      } else if (_lastThumbSelection == Thumb.end) {
1196
        _newValues = RangeValues(currentValues.start, math.max(currentDragValue, currentValues.start + _minThumbSeparationValue));
1197
      }
1198
      onChanged!(_newValues);
1199 1200 1201 1202
    }
  }

  void _endInteraction() {
1203 1204 1205 1206
    if (!_state.mounted) {
      return;
    }

1207 1208 1209 1210
    if (showValueIndicator && _state.interactionTimer == null) {
      _state.valueIndicatorController.reverse();
    }

1211 1212
    if (_active && _state.mounted && _lastThumbSelection != null) {
      final RangeValues discreteValues = _discretizeRangeValues(_newValues);
1213
      onChangeEnd?.call(discreteValues);
1214 1215
      _active = false;
    }
1216
    _state.overlayController.reverse();
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  }

  void _handleDragStart(DragStartDetails details) {
    _startInteraction(details.globalPosition);
  }

  void _handleDragEnd(DragEndDetails details) {
    _endInteraction();
  }

  void _handleDragCancel() {
    _endInteraction();
  }

  void _handleTapDown(TapDownDetails details) {
    _startInteraction(details.globalPosition);
  }

  void _handleTapUp(TapUpDetails details) {
    _endInteraction();
  }

  void _handleTapCancel() {
    _endInteraction();
  }

  @override
  bool hitTestSelf(Offset position) => true;

  @override
  void handleEvent(PointerEvent event, HitTestEntry entry) {
    assert(debugHandleEvent(event, entry));
    if (event is PointerDownEvent && isEnabled) {
      // We need to add the drag first so that it has priority.
      _drag.addPointer(event);
      _tap.addPointer(event);
    }
  }

  @override
  double computeMinIntrinsicWidth(double height) => _minPreferredTrackWidth + _maxSliderPartWidth;

  @override
  double computeMaxIntrinsicWidth(double height) => _minPreferredTrackWidth + _maxSliderPartWidth;

  @override
1263
  double computeMinIntrinsicHeight(double width) => math.max(_minPreferredTrackHeight!, _maxSliderPartHeight);
1264 1265

  @override
1266
  double computeMaxIntrinsicHeight(double width) => math.max(_minPreferredTrackHeight!, _maxSliderPartHeight);
1267 1268 1269 1270 1271

  @override
  bool get sizedByParent => true;

  @override
1272 1273
  Size computeDryLayout(BoxConstraints constraints) {
    return Size(
1274
      constraints.hasBoundedWidth ? constraints.maxWidth : _minPreferredTrackWidth + _maxSliderPartWidth,
1275
      constraints.hasBoundedHeight ? constraints.maxHeight : math.max(_minPreferredTrackHeight!, _maxSliderPartHeight),
1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286
    );
  }

  @override
  void paint(PaintingContext context, Offset offset) {
    final double startValue = _state.startPositionController.value;
    final double endValue = _state.endPositionController.value;

    // The visual position is the position of the thumb from 0 to 1 from left
    // to right. In left to right, this is the same as the value, but it is
    // reversed for right to left text.
1287 1288
    final double startVisualPosition;
    final double endVisualPosition;
1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299
    switch (textDirection) {
      case TextDirection.rtl:
        startVisualPosition = 1.0 - startValue;
        endVisualPosition = 1.0 - endValue;
        break;
      case TextDirection.ltr:
        startVisualPosition = startValue;
        endVisualPosition = endValue;
        break;
    }

1300
    final Rect trackRect = _sliderTheme.rangeTrackShape!.getPreferredRect(
1301 1302 1303
        parentBox: this,
        offset: offset,
        sliderTheme: _sliderTheme,
1304
        isDiscrete: isDiscrete,
1305 1306 1307 1308
    );
    final Offset startThumbCenter = Offset(trackRect.left + startVisualPosition * trackRect.width, trackRect.center.dy);
    final Offset endThumbCenter = Offset(trackRect.left + endVisualPosition * trackRect.width, trackRect.center.dy);

1309
    _sliderTheme.rangeTrackShape!.paint(
1310 1311 1312 1313 1314 1315 1316 1317 1318
        context,
        offset,
        parentBox: this,
        sliderTheme: _sliderTheme,
        enableAnimation: _enableAnimation,
        textDirection: _textDirection,
        startThumbCenter: startThumbCenter,
        endThumbCenter: endThumbCenter,
        isDiscrete: isDiscrete,
1319
        isEnabled: isEnabled,
1320 1321
    );

1322 1323
    final bool startThumbSelected = _lastThumbSelection == Thumb.start;
    final bool endThumbSelected = _lastThumbSelection == Thumb.end;
1324
    final Size resolvedscreenSize = screenSize.isEmpty ? size : screenSize;
1325

1326
    if (!_overlayAnimation.isDismissed) {
1327
      if (startThumbSelected) {
1328
        _sliderTheme.overlayShape!.paint(
1329 1330 1331 1332 1333 1334 1335 1336 1337 1338
          context,
          startThumbCenter,
          activationAnimation: _overlayAnimation,
          enableAnimation: _enableAnimation,
          isDiscrete: isDiscrete,
          labelPainter: _startLabelPainter,
          parentBox: this,
          sliderTheme: _sliderTheme,
          textDirection: _textDirection,
          value: startValue,
1339 1340
          textScaleFactor: _textScaleFactor,
          sizeWithOverflow: resolvedscreenSize,
1341 1342
        );
      }
1343
      if (endThumbSelected) {
1344
        _sliderTheme.overlayShape!.paint(
1345 1346 1347 1348 1349 1350 1351 1352 1353 1354
          context,
          endThumbCenter,
          activationAnimation: _overlayAnimation,
          enableAnimation: _enableAnimation,
          isDiscrete: isDiscrete,
          labelPainter: _endLabelPainter,
          parentBox: this,
          sliderTheme: _sliderTheme,
          textDirection: _textDirection,
          value: endValue,
1355 1356
          textScaleFactor: _textScaleFactor,
          sizeWithOverflow: resolvedscreenSize,
1357 1358 1359 1360 1361
        );
      }
    }

    if (isDiscrete) {
1362
      final double tickMarkWidth = _sliderTheme.rangeTickMarkShape!.getPreferredSize(
1363 1364 1365
        isEnabled: isEnabled,
        sliderTheme: _sliderTheme,
      ).width;
1366
      final double padding = trackRect.height;
1367
      final double adjustedTrackWidth = trackRect.width - padding;
1368
      // If the tick marks would be too dense, don't bother painting them.
1369
      if (adjustedTrackWidth / divisions! >= 3.0 * tickMarkWidth) {
1370
        final double dy = trackRect.center.dy;
1371 1372
        for (int i = 0; i <= divisions!; i++) {
          final double value = i / divisions!;
1373 1374
          // The ticks are mapped to be within the track, so the tick mark width
          // must be subtracted from the track width.
1375
          final double dx = trackRect.left + value * adjustedTrackWidth + padding / 2;
1376
          final Offset tickMarkOffset = Offset(dx, dy);
1377
          _sliderTheme.rangeTickMarkShape!.paint(
1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395
            context,
            tickMarkOffset,
            parentBox: this,
            sliderTheme: _sliderTheme,
            enableAnimation: _enableAnimation,
            textDirection: _textDirection,
            startThumbCenter: startThumbCenter,
            endThumbCenter: endThumbCenter,
            isEnabled: isEnabled,
          );
        }
      }
    }

    final double thumbDelta = (endThumbCenter.dx - startThumbCenter.dx).abs();

    final bool isLastThumbStart = _lastThumbSelection == Thumb.start;
    final Thumb bottomThumb = isLastThumbStart ? Thumb.end : Thumb.start;
1396
    final Thumb topThumb = isLastThumbStart ? Thumb.start : Thumb.end;
1397 1398 1399 1400 1401 1402
    final Offset bottomThumbCenter = isLastThumbStart ? endThumbCenter : startThumbCenter;
    final Offset topThumbCenter = isLastThumbStart ? startThumbCenter : endThumbCenter;
    final TextPainter bottomLabelPainter = isLastThumbStart ? _endLabelPainter : _startLabelPainter;
    final TextPainter topLabelPainter = isLastThumbStart ? _startLabelPainter : _endLabelPainter;
    final double bottomValue = isLastThumbStart ? endValue : startValue;
    final double topValue = isLastThumbStart ? startValue : endValue;
1403
    final bool shouldPaintValueIndicators = isEnabled && labels != null && !_valueIndicatorAnimation.isDismissed && showValueIndicator;
1404

1405
    if (shouldPaintValueIndicators) {
1406
      _state.paintBottomValueIndicator = (PaintingContext context, Offset offset) {
1407
        if (attached) {
1408
          _sliderTheme.rangeValueIndicatorShape!.paint(
1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424
            context,
            bottomThumbCenter,
            activationAnimation: _valueIndicatorAnimation,
            enableAnimation: _enableAnimation,
            isDiscrete: isDiscrete,
            isOnTop: false,
            labelPainter: bottomLabelPainter,
            parentBox: this,
            sliderTheme: _sliderTheme,
            textDirection: _textDirection,
            thumb: bottomThumb,
            value: bottomValue,
            textScaleFactor: textScaleFactor,
            sizeWithOverflow: resolvedscreenSize,
          );
        }
1425
      };
1426 1427
    }

1428
    _sliderTheme.rangeThumbShape!.paint(
1429 1430 1431 1432 1433 1434 1435 1436 1437
      context,
      bottomThumbCenter,
      activationAnimation: _valueIndicatorAnimation,
      enableAnimation: _enableAnimation,
      isDiscrete: isDiscrete,
      isOnTop: false,
      textDirection: textDirection,
      sliderTheme: _sliderTheme,
      thumb: bottomThumb,
1438
      isPressed: bottomThumb == Thumb.start ? startThumbSelected : endThumbSelected,
1439 1440 1441
    );

    if (shouldPaintValueIndicators) {
1442
      final double startOffset = sliderTheme.rangeValueIndicatorShape!.getHorizontalShift(
1443 1444 1445 1446
        parentBox: this,
        center: startThumbCenter,
        labelPainter: _startLabelPainter,
        activationAnimation: _valueIndicatorAnimation,
1447 1448
        textScaleFactor: textScaleFactor,
        sizeWithOverflow: resolvedscreenSize,
1449
      );
1450
      final double endOffset = sliderTheme.rangeValueIndicatorShape!.getHorizontalShift(
1451 1452 1453 1454
        parentBox: this,
        center: endThumbCenter,
        labelPainter: _endLabelPainter,
        activationAnimation: _valueIndicatorAnimation,
1455 1456
        textScaleFactor: textScaleFactor,
        sizeWithOverflow: resolvedscreenSize,
1457
      );
1458
      final double startHalfWidth = sliderTheme.rangeValueIndicatorShape!.getPreferredSize(
1459 1460 1461 1462 1463
        isEnabled,
        isDiscrete,
        labelPainter: _startLabelPainter,
        textScaleFactor: textScaleFactor,
      ).width / 2;
1464
      final double endHalfWidth = sliderTheme.rangeValueIndicatorShape!.getPreferredSize(
1465 1466 1467 1468 1469
        isEnabled,
        isDiscrete,
        labelPainter: _endLabelPainter,
        textScaleFactor: textScaleFactor,
      ).width / 2;
1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481
      double innerOverflow = startHalfWidth + endHalfWidth;
      switch (textDirection) {
        case TextDirection.ltr:
          innerOverflow += startOffset;
          innerOverflow -= endOffset;
          break;
        case TextDirection.rtl:
          innerOverflow -= startOffset;
          innerOverflow += endOffset;
          break;
      }

1482
      _state.paintTopValueIndicator = (PaintingContext context, Offset offset) {
1483
        if (attached) {
1484
          _sliderTheme.rangeValueIndicatorShape!.paint(
1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500
            context,
            topThumbCenter,
            activationAnimation: _valueIndicatorAnimation,
            enableAnimation: _enableAnimation,
            isDiscrete: isDiscrete,
            isOnTop: thumbDelta < innerOverflow,
            labelPainter: topLabelPainter,
            parentBox: this,
            sliderTheme: _sliderTheme,
            textDirection: _textDirection,
            thumb: topThumb,
            value: topValue,
            textScaleFactor: textScaleFactor,
            sizeWithOverflow: resolvedscreenSize,
          );
        }
1501
      };
1502 1503
    }

1504
    _sliderTheme.rangeThumbShape!.paint(
1505 1506
      context,
      topThumbCenter,
1507
      activationAnimation: _overlayAnimation,
1508 1509
      enableAnimation: _enableAnimation,
      isDiscrete: isDiscrete,
1510
      isOnTop: thumbDelta < sliderTheme.rangeThumbShape!.getPreferredSize(isEnabled, isDiscrete).width,
1511
      textDirection: textDirection,
1512
      sliderTheme: _sliderTheme,
1513
      thumb: topThumb,
1514
      isPressed: topThumb == Thumb.start ? startThumbSelected : endThumbSelected,
1515 1516 1517
    );
  }

1518
  /// Describe the semantics of the start thumb.
1519
  SemanticsNode? _startSemanticsNode = SemanticsNode();
1520 1521

  /// Describe the semantics of the end thumb.
1522
  SemanticsNode? _endSemanticsNode = SemanticsNode();
1523

1524 1525
  // Create the semantics configuration for a single value.
  SemanticsConfiguration _createSemanticsConfiguration(
1526 1527 1528 1529 1530
    double value,
    double increasedValue,
    double decreasedValue,
    VoidCallback increaseAction,
    VoidCallback decreaseAction,
1531 1532 1533 1534
  ) {
    final SemanticsConfiguration config = SemanticsConfiguration();
    config.isEnabled = isEnabled;
    config.textDirection = textDirection;
1535
    config.isSlider = true;
1536
    if (isEnabled) {
1537 1538 1539
      config.onIncrease = increaseAction;
      config.onDecrease = decreaseAction;
    }
1540

1541
    if (semanticFormatterCallback != null) {
1542 1543 1544
      config.value = semanticFormatterCallback!(_state._lerp(value));
      config.increasedValue = semanticFormatterCallback!(_state._lerp(increasedValue));
      config.decreasedValue = semanticFormatterCallback!(_state._lerp(decreasedValue));
1545 1546 1547 1548
    } else {
      config.value = '${(value * 100).round()}%';
      config.increasedValue = '${(increasedValue * 100).round()}%';
      config.decreasedValue = '${(decreasedValue * 100).round()}%';
1549
    }
1550 1551

    return config;
1552 1553
  }

1554 1555
  @override
  void assembleSemanticsNode(
1556 1557 1558
    SemanticsNode node,
    SemanticsConfiguration config,
    Iterable<SemanticsNode> children,
1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581
  ) {
    assert(children.isEmpty);

    final SemanticsConfiguration startSemanticsConfiguration = _createSemanticsConfiguration(
      values.start,
      _increasedStartValue,
      _decreasedStartValue,
      _increaseStartAction,
      _decreaseStartAction,
    );
    final SemanticsConfiguration endSemanticsConfiguration = _createSemanticsConfiguration(
      values.end,
      _increasedEndValue,
      _decreasedEndValue,
      _increaseEndAction,
      _decreaseEndAction,
    );

    // Split the semantics node area between the start and end nodes.
    final Rect leftRect = Rect.fromPoints(node.rect.topLeft, node.rect.bottomCenter);
    final Rect rightRect = Rect.fromPoints(node.rect.topCenter, node.rect.bottomRight);
    switch (textDirection) {
      case TextDirection.ltr:
1582 1583
        _startSemanticsNode!.rect = leftRect;
        _endSemanticsNode!.rect = rightRect;
1584 1585
        break;
      case TextDirection.rtl:
1586 1587
        _startSemanticsNode!.rect = rightRect;
        _endSemanticsNode!.rect = leftRect;
1588 1589 1590
        break;
    }

1591 1592
    _startSemanticsNode!.updateWith(config: startSemanticsConfiguration);
    _endSemanticsNode!.updateWith(config: endSemanticsConfiguration);
1593 1594

    final List<SemanticsNode> finalChildren = <SemanticsNode>[
1595 1596
      _startSemanticsNode!,
      _endSemanticsNode!,
1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613
    ];

    node.updateWith(config: config, childrenInInversePaintOrder: finalChildren);
  }

  @override
  void clearSemantics() {
    super.clearSemantics();
    _startSemanticsNode = null;
    _endSemanticsNode = null;
  }

  @override
  void describeSemanticsConfiguration(SemanticsConfiguration config) {
    super.describeSemanticsConfiguration(config);
    config.isSemanticBoundary = true;
  }
1614

1615
  double get _semanticActionUnit => divisions != null ? 1.0 / divisions! : _adjustmentUnit;
1616 1617 1618

  void _increaseStartAction() {
    if (isEnabled) {
1619
      onChanged!(RangeValues(_increasedStartValue, values.end));
1620 1621 1622 1623 1624
    }
  }

  void _decreaseStartAction() {
    if (isEnabled) {
1625
      onChanged!(RangeValues(_decreasedStartValue, values.end));
1626 1627 1628 1629 1630
    }
  }

  void _increaseEndAction() {
    if (isEnabled) {
1631
      onChanged!(RangeValues(values.start, _increasedEndValue));
1632 1633 1634 1635 1636
    }
  }

  void _decreaseEndAction() {
    if (isEnabled) {
1637
      onChanged!(RangeValues(values.start, _decreasedEndValue));
1638 1639 1640
    }
  }

1641 1642 1643 1644 1645 1646 1647 1648
  double get _increasedStartValue {
    // Due to floating-point operations, this value can actually be greater than
    // expected (e.g. 0.4 + 0.2 = 0.600000000001), so we limit to 2 decimal points.
    final double increasedStartValue = double.parse((values.start + _semanticActionUnit).toStringAsFixed(2));
    return increasedStartValue <= values.end - _minThumbSeparationValue ? increasedStartValue : values.start;
  }

  double get _decreasedStartValue {
1649
    return clampDouble(values.start - _semanticActionUnit, 0.0, 1.0);
1650 1651 1652
  }

  double get _increasedEndValue {
1653
    return clampDouble(values.end + _semanticActionUnit, 0.0, 1.0);
1654 1655
  }

1656 1657 1658
  double get _decreasedEndValue {
    final double decreasedEndValue = values.end - _semanticActionUnit;
    return decreasedEndValue >= values.start + _minThumbSeparationValue ? decreasedEndValue : values.end;
1659
  }
1660
}
1661 1662 1663 1664


class _ValueIndicatorRenderObjectWidget extends LeafRenderObjectWidget {
  const _ValueIndicatorRenderObjectWidget({
1665
    required this.state,
1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683
  });

  final _RangeSliderState state;

  @override
  _RenderValueIndicator createRenderObject(BuildContext context) {
    return _RenderValueIndicator(
      state: state,
    );
  }
  @override
  void updateRenderObject(BuildContext context, _RenderValueIndicator renderObject) {
    renderObject._state = state;
  }
}

class _RenderValueIndicator extends RenderBox with RelayoutWhenSystemFontsChangeMixin {
  _RenderValueIndicator({
1684
    required _RangeSliderState state,
1685 1686 1687 1688 1689 1690 1691
  }) :_state = state {
    _valueIndicatorAnimation = CurvedAnimation(
      parent: _state.valueIndicatorController,
      curve: Curves.fastOutSlowIn,
    );
  }

1692 1693
  late Animation<double> _valueIndicatorAnimation;
  late _RangeSliderState _state;
1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715

  @override
  bool get sizedByParent => true;

  @override
  void attach(PipelineOwner owner) {
    super.attach(owner);
    _valueIndicatorAnimation.addListener(markNeedsPaint);
    _state.startPositionController.addListener(markNeedsPaint);
    _state.endPositionController.addListener(markNeedsPaint);
  }

  @override
  void detach() {
    _valueIndicatorAnimation.removeListener(markNeedsPaint);
    _state.startPositionController.removeListener(markNeedsPaint);
    _state.endPositionController.removeListener(markNeedsPaint);
    super.detach();
  }

  @override
  void paint(PaintingContext context, Offset offset) {
1716 1717
    _state.paintBottomValueIndicator?.call(context, offset);
    _state.paintTopValueIndicator?.call(context, offset);
1718
  }
1719 1720 1721 1722 1723

  @override
  Size computeDryLayout(BoxConstraints constraints) {
    return constraints.smallest;
  }
1724
}