Update switch

Runtime/material/switch.cs

 using Unity.UIWidgets.foundation;
 using Unity.UIWidgets.gestures;
-using Unity.UIWidgets.material;
 using Unity.UIWidgets.painting;
 using Unity.UIWidgets.rendering;
 using Unity.UIWidgets.scheduler;
             Color inactiveTrackColor = null,
             ImageProvider activeThumbImage = null,
             ImageProvider inactiveThumbImage = null,
-            MaterialTapTargetSize? materialTapTargetSize = null
+            MaterialTapTargetSize? materialTapTargetSize = null,
+            DragStartBehavior dragStartBehavior = DragStartBehavior.down
         ) : this(
             key: key,
             value: value,
             activeThumbImage: activeThumbImage,
             inactiveThumbImage: inactiveThumbImage,
             materialTapTargetSize: materialTapTargetSize,
-            switchType: _SwitchType.material
+            switchType: _SwitchType.material,
+            dragStartBehavior: dragStartBehavior
         ) {
         }
 
             ImageProvider activeThumbImage = null,
             ImageProvider inactiveThumbImage = null,
             MaterialTapTargetSize? materialTapTargetSize = null,
-            _SwitchType switchType = _SwitchType.material
+            _SwitchType switchType = _SwitchType.material,
+            DragStartBehavior dragStartBehavior = DragStartBehavior.down
         ) : base(key: key) {
             D.assert(value != null);
             this.value = value.Value;
             this.inactiveThumbImage = inactiveThumbImage;
             this.materialTapTargetSize = materialTapTargetSize;
             this._switchType = switchType;
+            this.dragStartBehavior = dragStartBehavior;
         }
 
         public static Switch adaptive(
             Color inactiveTrackColor = null,
             ImageProvider activeThumbImage = null,
             ImageProvider inactiveThumbImage = null,
-            MaterialTapTargetSize? materialTapTargetSize = null
+            MaterialTapTargetSize? materialTapTargetSize = null,
+            DragStartBehavior dragStartBehavior = DragStartBehavior.down
         ) {
             return new Switch(key: key,
                 value: value,
 
         internal readonly _SwitchType _switchType;
 
+        public readonly DragStartBehavior dragStartBehavior;
+
         public override State createState() {
             return new _SwitchState();
         }
             properties.add(new FlagProperty("value", value: this.value, ifTrue: "on", ifFalse: "off", showName: true));
-            properties.add(new ObjectFlagProperty<ValueChanged<bool?>>("onChanged", this.onChanged, ifNull: "disabled"));
+            properties.add(
+                new ObjectFlagProperty<ValueChanged<bool?>>("onChanged", this.onChanged, ifNull: "disabled"));
         }
     }
 
                 case MaterialTapTargetSize.shrinkWrap:
                     return new Size(Switch._kSwitchWidth, Switch._kSwitchHeightCollapsed);
             }
+
             D.assert(false);
             return null;
         }
                 inactiveThumbColor = this.widget.inactiveThumbColor ??
                                      (isDark ? Colors.grey.shade400 : Colors.grey.shade50);
                 inactiveTrackColor = this.widget.inactiveTrackColor ?? (isDark ? Colors.white30 : black32);
-            } else {
+            }
+            else {
                 inactiveThumbColor = this.widget.inactiveThumbColor ??
                                      (isDark ? Colors.grey.shade800 : Colors.grey.shade400);
                 inactiveTrackColor = this.widget.inactiveTrackColor ?? (isDark ? Colors.white10 : Colors.black12);
+                dragStartBehavior: this.widget.dragStartBehavior,
                 value: this.widget.value,
                 activeColor: activeThumbColor,
                 inactiveColor: inactiveThumbColor,
             ImageConfiguration configuration = null,
             ValueChanged<bool?> onChanged = null,
             TickerProvider vsync = null,
-            BoxConstraints additionalConstraints = null
+            BoxConstraints additionalConstraints = null,
+            DragStartBehavior? dragStartBehavior = null
         ) : base(key: key) {
             D.assert(value != null);
             this.value = value.Value;
             this.onChanged = onChanged;
             this.vsync = vsync;
             this.additionalConstraints = additionalConstraints;
+            this.dragStartBehavior = dragStartBehavior;
         }
 
         public readonly bool value;
         public readonly ValueChanged<bool?> onChanged;
         public readonly TickerProvider vsync;
         public readonly BoxConstraints additionalConstraints;
+        public readonly DragStartBehavior? dragStartBehavior;
+                dragStartBehavior: this.dragStartBehavior,
                 value: this.value,
                 activeColor: this.activeColor,
                 inactiveColor: this.inactiveColor,
             renderObject.configuration = this.configuration;
             renderObject.onChanged = this.onChanged;
             renderObject.additionalConstraints = this.additionalConstraints;
+            renderObject.dragStartBehavior = this.dragStartBehavior;
             renderObject.vsync = this.vsync;
         }
     }
             ImageConfiguration configuration = null,
             BoxConstraints additionalConstraints = null,
             ValueChanged<bool?> onChanged = null,
-            TickerProvider vsync = null
+            TickerProvider vsync = null,
+            DragStartBehavior? dragStartBehavior = null
         ) : base(
             value: value,
             tristate: false,
                 onStart = this._handleDragStart,
                 onUpdate = this._handleDragUpdate,
                 onEnd = this._handleDragEnd,
+                dragStartBehavior = dragStartBehavior ?? DragStartBehavior.down
             };
         }
 
                 if (value == this._activeThumbImage) {
                     return;
                 }
+
                 this._activeThumbImage = value;
                 this.markNeedsPaint();
             }
                 if (value == this._inactiveThumbImage) {
                     return;
                 }
+
                 this._inactiveThumbImage = value;
                 this.markNeedsPaint();
             }
                 if (value == this._activeTrackColor) {
                     return;
                 }
+
                 this._activeTrackColor = value;
                 this.markNeedsPaint();
             }
                 if (value == this._inactiveTrackColor) {
                     return;
                 }
+
                 this._inactiveTrackColor = value;
                 this.markNeedsPaint();
             }
                 if (value == this._configuration) {
                     return;
                 }
+
                 this._configuration = value;
                 this.markNeedsPaint();
             }
+
+        public DragStartBehavior? dragStartBehavior {
+            get { return this._drag.dragStartBehavior; }
+            set { this._drag.dragStartBehavior = value ?? DragStartBehavior.down; }
+        }
+
 
         public override void detach() {
             this._cachedThumbPainter?.Dispose();
         void _handleDragEnd(DragEndDetails details) {
             if (this.position.value >= 0.5) {
                 this.positionController.forward();
-            } else {
+            }
+            else {
+
             this.reactionController.reverse();
         }
 
                 this._drag.addPointer((PointerDownEvent) evt);
             }
+
             base.handleEvent(evt, entry);
         }
 
         public override void paint(PaintingContext context, Offset offset) {
             Canvas canvas = context.canvas;
 
-            bool isActive = this.onChanged != null;
+            bool isEnabled = this.onChanged != null;
-            Color trackColor = isActive
+            Color trackColor = isEnabled
+            Color thumbColor = isEnabled
+                ? Color.lerp(this.inactiveColor, this.activeColor, currentValue)
+                : this.inactiveColor;
+
+            ImageProvider thumbImage = isEnabled
+                ? (currentValue < 0.5 ? this.inactiveThumbImage : this.activeThumbImage)
+                : this.inactiveThumbImage;
+
             // Paint the track
             Paint paint = new Paint {color = trackColor};
             float trackHorizontalPadding = Constants.kRadialReactionRadius - Switch._kTrackRadius;
             try {
                 this._isPainting = true;
                 BoxPainter thumbPainter;
-                Color thumbColor = isActive
-                    ? Color.lerp(this.inactiveColor, this.activeColor, currentValue)
-                    : this.inactiveColor;
-                ImageProvider thumbImage = isActive
-                    ? (currentValue < 0.5 ? this.inactiveThumbImage : this.activeThumbImage)
-                    : this.inactiveThumbImage;
                 if (this._cachedThumbPainter == null || thumbColor != this._cachedThumbColor ||
                     thumbImage != this._cachedThumbImage) {
                     this._cachedThumbColor = thumbColor;
                 }
+
                 thumbPainter = this._cachedThumbPainter;
 
                 float inset = 1.0f - (currentValue - 0.5f).abs() * 2.0f;
                     thumbPosition + offset - new Offset(radius, radius),
                     this.configuration.copyWith(size: Size.fromRadius(radius))
                 );
-            } finally {
+            }
+            finally {
-}
+}