[Cupertino] Implement slider.

Runtime/cupertino/slider.cs

+using System;
+using Unity.UIWidgets.animation;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.gestures;
+using Unity.UIWidgets.rendering;
+using Unity.UIWidgets.scheduler;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using UnityEngine;
+using Canvas = Unity.UIWidgets.ui.Canvas;
+using Color = Unity.UIWidgets.ui.Color;
+using Rect = Unity.UIWidgets.ui.Rect;
+
+namespace Unity.UIWidgets.cupertino {
+    class SliderUtils {
+        public const float _kPadding = 8.0f;
+        public static readonly Color _kTrackColor = new Color(0xFFB5B5B5);
+        public const float _kSliderHeight = 2.0f * (CupertinoThumbPainter.radius + _kPadding);
+        public const float _kSliderWidth = 176.0f; // Matches Material Design slider.
+        public static readonly TimeSpan _kDiscreteTransitionDuration = new TimeSpan(0, 0, 0, 0, 500);
+        public const float _kAdjustmentUnit = 0.1f; // Matches iOS implementation of material slider.
+    }
+
+    public class CupertinoSlider : StatefulWidget {
+        public CupertinoSlider(
+            Key key = null,
+            float? value = null,
+            ValueChanged<float> onChanged = null,
+            ValueChanged<float> onChangeStart = null,
+            ValueChanged<float> onChangeEnd = null,
+            float min = 0.0f,
+            float max = 1.0f,
+            int? divisions = null,
+            Color activeColor = null
+        ) : base(key: key) {
+            D.assert(value != null);
+            D.assert(onChanged != null);
+            D.assert(min != null);
+            D.assert(max != null);
+            D.assert(value >= min && value <= max);
+            D.assert(divisions == null || divisions > 0);
+            this.value = value.Value;
+            this.onChanged = onChanged;
+            this.onChangeStart = onChangeStart;
+            this.onChangeEnd = onChangeEnd;
+            this.min = min;
+            this.max = max;
+            this.divisions = divisions;
+            this.activeColor = activeColor;
+        }
+
+        public readonly float value;
+
+        public readonly ValueChanged<float> onChanged;
+
+        public readonly ValueChanged<float> onChangeStart;
+
+        public readonly ValueChanged<float> onChangeEnd;
+
+        public readonly float min;
+
+        public readonly float max;
+
+        public readonly int? divisions;
+
+        public readonly Color activeColor;
+
+        public override State createState() {
+            return new _CupertinoSliderState();
+        }
+
+        public override void debugFillProperties(DiagnosticPropertiesBuilder properties) {
+            base.debugFillProperties(properties);
+            properties.add(new FloatProperty("value", this.value));
+            properties.add(new FloatProperty("min", this.min));
+            properties.add(new FloatProperty("max", this.max));
+        }
+    }
+
+    class _CupertinoSliderState : TickerProviderStateMixin<CupertinoSlider> {
+        void _handleChanged(float value) {
+            D.assert(this.widget.onChanged != null);
+            float lerpValue = MathUtils.lerpFloat(this.widget.min, this.widget.max, value);
+            if (lerpValue != this.widget.value) {
+                this.widget.onChanged(lerpValue);
+            }
+        }
+
+        void _handleDragStart(float value) {
+            D.assert(this.widget.onChangeStart != null);
+            this.widget.onChangeStart(MathUtils.lerpFloat(this.widget.min, this.widget.max, value));
+        }
+
+        void _handleDragEnd(float value) {
+            D.assert(this.widget.onChangeEnd != null);
+            this.widget.onChangeEnd(MathUtils.lerpFloat(this.widget.min, this.widget.max, value));
+        }
+
+        public override Widget build(BuildContext context) {
+            return new _CupertinoSliderRenderObjectWidget(
+                value: (this.widget.value - this.widget.min) / (this.widget.max - this.widget.min),
+                divisions: this.widget.divisions,
+                activeColor: this.widget.activeColor ?? CupertinoTheme.of(context).primaryColor,
+                onChanged: this.widget.onChanged != null ? (ValueChanged<float>) this._handleChanged : null,
+                onChangeStart: this.widget.onChangeStart != null ? (ValueChanged<float>) this._handleDragStart : null,
+                onChangeEnd: this.widget.onChangeEnd != null ? (ValueChanged<float>) this._handleDragEnd : null,
+                vsync: this
+            );
+        }
+    }
+
+    class _CupertinoSliderRenderObjectWidget : LeafRenderObjectWidget {
+        public _CupertinoSliderRenderObjectWidget(
+            Key key = null,
+            float? value = null,
+            int? divisions = null,
+            Color activeColor = null,
+            ValueChanged<float> onChanged = null,
+            ValueChanged<float> onChangeStart = null,
+            ValueChanged<float> onChangeEnd = null,
+            TickerProvider vsync = null
+        ) : base(key: key) {
+            this.value = value;
+            this.divisions = divisions;
+            this.activeColor = activeColor;
+            this.onChanged = onChanged;
+            this.onChangeStart = onChangeStart;
+            this.onChangeEnd = onChangeEnd;
+            this.vsync = vsync;
+        }
+
+        public readonly float? value;
+        public readonly int? divisions;
+        public readonly Color activeColor;
+        public readonly ValueChanged<float> onChanged;
+        public readonly ValueChanged<float> onChangeStart;
+        public readonly ValueChanged<float> onChangeEnd;
+        public readonly TickerProvider vsync;
+
+        public override RenderObject createRenderObject(BuildContext context) {
+            return new _RenderCupertinoSlider(
+                value: this.value ?? 0.0f,
+                divisions: this.divisions,
+                activeColor: this.activeColor,
+                onChanged: this.onChanged,
+                onChangeStart: this.onChangeStart,
+                onChangeEnd: this.onChangeEnd,
+                vsync: this.vsync
+            );
+        }
+
+        public override void updateRenderObject(BuildContext context, RenderObject _renderObject) {
+            _RenderCupertinoSlider renderObject = _renderObject as _RenderCupertinoSlider;
+            renderObject.value = this.value ?? 0.0f;
+            renderObject.divisions = this.divisions ?? 0;
+            renderObject.activeColor = this.activeColor;
+            renderObject.onChanged = this.onChanged;
+            renderObject.onChangeStart = this.onChangeStart;
+            renderObject.onChangeEnd = this.onChangeEnd;
+        }
+    }
+
+    class _RenderCupertinoSlider : RenderConstrainedBox {
+        public _RenderCupertinoSlider(
+            float value,
+            int? divisions = null,
+            Color activeColor = null,
+            ValueChanged<float> onChanged = null,
+            ValueChanged<float> onChangeStart = null,
+            ValueChanged<float> onChangeEnd = null,
+            TickerProvider vsync = null
+        ) : base(additionalConstraints: BoxConstraints.tightFor(width: SliderUtils._kSliderWidth,
+            height: SliderUtils._kSliderHeight)) {
+            D.assert(value != null && value >= 0.0f && value <= 1.0f);
+            this._value = value;
+            this._divisions = divisions;
+            this._activeColor = activeColor;
+            this._onChanged = onChanged;
+            this._drag = new HorizontalDragGestureRecognizer();
+            this._drag.onStart = this._handleDragStart;
+            this._drag.onUpdate = this._handleDragUpdate;
+            this._drag.onEnd = this._handleDragEnd;
+            this._position = new AnimationController(
+                value: value,
+                duration: SliderUtils._kDiscreteTransitionDuration,
+                vsync: vsync
+            );
+            this._position.addListener(this.markNeedsPaint);
+        }
+
+        public float value {
+            get { return this._value; }
+            set {
+                D.assert(value != null && value >= 0.0f && value <= 1.0f);
+                if (value == this._value) {
+                    return;
+                }
+
+                this._value = value;
+                if (this.divisions != null) {
+                    this._position.animateTo(value, curve: Curves.fastOutSlowIn);
+                }
+                else {
+                    this._position.setValue(value);
+                }
+            }
+        }
+
+        float _value;
+
+        public int? divisions {
+            get { return this._divisions; }
+            set {
+                if (value == this._divisions) {
+                    return;
+                }
+
+                this._divisions = value;
+                this.markNeedsPaint();
+            }
+        }
+
+        int? _divisions;
+
+        public Color activeColor {
+            get { return this._activeColor; }
+            set {
+                if (value == this._activeColor) {
+                    return;
+                }
+
+                this._activeColor = value;
+                this.markNeedsPaint();
+            }
+        }
+
+        Color _activeColor;
+
+        public ValueChanged<float> onChanged {
+            get { return this._onChanged; }
+            set {
+                if (value == this._onChanged) {
+                    return;
+                }
+
+                this._onChanged = value;
+            }
+        }
+
+        ValueChanged<float> _onChanged;
+
+        public ValueChanged<float> onChangeStart;
+        public ValueChanged<float> onChangeEnd;
+
+
+        AnimationController _position;
+
+        HorizontalDragGestureRecognizer _drag;
+        float _currentDragValue = 0.0f;
+
+        float _discretizedCurrentDragValue {
+            get {
+                float dragValue = this._currentDragValue.clamp(0.0f, 1.0f);
+                if (this.divisions != null) {
+                    dragValue = Mathf.Round(dragValue * this.divisions.Value) / this.divisions.Value;
+                }
+
+                return dragValue;
+            }
+        }
+
+        public float _trackLeft {
+            get { return SliderUtils._kPadding; }
+        }
+
+        public float _trackRight {
+            get { return this.size.width - SliderUtils._kPadding; }
+        }
+
+        float _thumbCenter {
+            get {
+                float visualPosition = this._value;
+
+                return MathUtils.lerpFloat(this._trackLeft + CupertinoThumbPainter.radius,
+                    this._trackRight - CupertinoThumbPainter.radius,
+                    visualPosition);
+            }
+        }
+
+        public bool isInteractive {
+            get { return this.onChanged != null; }
+        }
+
+        void _handleDragStart(DragStartDetails details) {
+            this._startInteraction(details.globalPosition);
+        }
+
+        void _handleDragUpdate(DragUpdateDetails details) {
+            if (this.isInteractive) {
+                float extent = Mathf.Max(SliderUtils._kPadding,
+                    this.size.width - 2.0f * (SliderUtils._kPadding + CupertinoThumbPainter.radius));
+                float? valueDelta = details.primaryDelta / extent;
+                this._currentDragValue += valueDelta ?? 0.0f;
+
+                this.onChanged(this._discretizedCurrentDragValue);
+            }
+        }
+
+        void _handleDragEnd(DragEndDetails details) {
+            this._endInteraction();
+        }
+
+        void _startInteraction(Offset globalPosition) {
+            if (this.isInteractive) {
+                if (this.onChangeStart != null) {
+                    this.onChangeStart(this._discretizedCurrentDragValue);
+                }
+
+                this._currentDragValue = this._value;
+                this.onChanged(this._discretizedCurrentDragValue);
+            }
+        }
+
+        void _endInteraction() {
+            if (this.onChangeEnd != null) {
+                this.onChangeEnd(this._discretizedCurrentDragValue);
+            }
+
+            this._currentDragValue = 0.0f;
+        }
+
+        protected override bool hitTestSelf(Offset position) {
+            return (position.dx - this._thumbCenter).abs() < CupertinoThumbPainter.radius + SliderUtils._kPadding;
+        }
+
+        public override void handleEvent(PointerEvent e, HitTestEntry entry) {
+            D.assert(this.debugHandleEvent(e, entry));
+            if (e is PointerDownEvent pointerDownEvent && this.isInteractive) {
+                this._drag.addPointer(pointerDownEvent);
+            }
+        }
+
+        CupertinoThumbPainter _thumbPainter = new CupertinoThumbPainter();
+
+        public override
+            void paint(PaintingContext context, Offset offset) {
+            float visualPosition;
+            Color leftColor;
+            Color rightColor;
+            visualPosition = this._position.value;
+            leftColor = SliderUtils._kTrackColor;
+            rightColor = this._activeColor;
+
+            float trackCenter = offset.dy + this.size.height / 2.0f;
+            float trackLeft = offset.dx + this._trackLeft;
+            float trackTop = trackCenter - 1.0f;
+            float trackBottom = trackCenter + 1.0f;
+            float trackRight = offset.dx + this._trackRight;
+            float trackActive = offset.dx + this._thumbCenter;
+
+            Canvas canvas = context.canvas;
+
+            if (visualPosition > 0.0f) {
+                Paint paint = new Paint();
+                paint.color = rightColor;
+                canvas.drawRRect(RRect.fromLTRBXY(trackLeft, trackTop, trackActive, trackBottom, 1.0f, 1.0f), paint);
+            }
+
+            if (visualPosition < 1.0f) {
+                Paint paint = new Paint();
+                paint.color = leftColor;
+                canvas.drawRRect(RRect.fromLTRBXY(trackActive, trackTop, trackRight, trackBottom, 1.0f, 1.0f), paint);
+            }
+
+            Offset thumbCenter = new Offset(trackActive, trackCenter);
+            this._thumbPainter.paint(canvas,
+                Rect.fromCircle(center: thumbCenter, radius: CupertinoThumbPainter.radius));
+        }
+    }
+}

Runtime/cupertino/slider.cs.meta

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+guid: 9d6aaa856d879be40833f2ae7ec103ac
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+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
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