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lib/src/behaviors/select_nearest.dart

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+// Copyright 2018 the Charts project authors. Please see the AUTHORS file
+// for details.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'package:charts_common/common.dart' as common
+    show
+        ChartBehavior,
+        SelectNearest,
+        SelectionMode,
+        SelectionModelType,
+        SelectionTrigger;
+
+import 'package:meta/meta.dart' show immutable;
+
+import 'chart_behavior.dart' show ChartBehavior, GestureType;
+
+/// Chart behavior that listens to the given eventTrigger and updates the
+/// specified [SelectionModel]. This is used to pair input events to behaviors
+/// that listen to selection changes.
+///
+/// Input event types:
+///   hover (default) - Mouse over/near data.
+///   tap - Mouse/Touch on/near data.
+///   pressHold - Mouse/Touch and drag across the data instead of panning.
+///   longPressHold - Mouse/Touch for a while in one place then drag across the data.
+///
+/// SelectionModels that can be updated:
+///   info - To view the details of the selected items (ie: hover for web).
+///   action - To select an item as an input, drill, or other selection.
+///
+/// Other options available
+///   selectionMode - Optional mode for expanding the selection beyond the
+///       nearest datum. Defaults to expandToDomain.
+///   selectClosestSeries - mark the series for the closest data point as
+///       selected. (Default: true)
+///
+/// You can add one SelectNearest for each model type that you are updating.
+/// Any previous SelectNearest behavior for that selection model will be
+/// removed.
+@immutable
+class SelectNearest<D> extends ChartBehavior<D> {
+  final Set<GestureType> desiredGestures;
+
+  final common.SelectionModelType selectionModelType;
+  final common.SelectionTrigger eventTrigger;
+  final common.SelectionMode selectionMode;
+  final bool selectAcrossAllDrawAreaComponents;
+  final bool selectClosestSeries;
+  final int? maximumDomainDistancePx;
+
+  SelectNearest._internal(
+      {required this.selectionModelType,
+      this.selectionMode = common.SelectionMode.expandToDomain,
+      this.selectAcrossAllDrawAreaComponents = false,
+      this.selectClosestSeries = true,
+      required this.eventTrigger,
+      required this.desiredGestures,
+      this.maximumDomainDistancePx});
+
+  factory SelectNearest(
+      {common.SelectionModelType selectionModelType =
+          common.SelectionModelType.info,
+      common.SelectionMode selectionMode = common.SelectionMode.expandToDomain,
+      bool selectAcrossAllDrawAreaComponents = false,
+      bool selectClosestSeries = true,
+      common.SelectionTrigger eventTrigger = common.SelectionTrigger.tap,
+      int? maximumDomainDistancePx}) {
+    return new SelectNearest._internal(
+        selectionModelType: selectionModelType,
+        selectionMode: selectionMode,
+        selectAcrossAllDrawAreaComponents: selectAcrossAllDrawAreaComponents,
+        selectClosestSeries: selectClosestSeries,
+        eventTrigger: eventTrigger,
+        desiredGestures: SelectNearest._getDesiredGestures(eventTrigger),
+        maximumDomainDistancePx: maximumDomainDistancePx);
+  }
+
+  static Set<GestureType> _getDesiredGestures(
+      common.SelectionTrigger eventTrigger) {
+    final desiredGestures = new Set<GestureType>();
+    switch (eventTrigger) {
+      case common.SelectionTrigger.tap:
+        desiredGestures..add(GestureType.onTap);
+        break;
+      case common.SelectionTrigger.tapAndDrag:
+        desiredGestures
+          ..add(GestureType.onTap)
+          ..add(GestureType.onDrag);
+        break;
+      case common.SelectionTrigger.pressHold:
+      case common.SelectionTrigger.longPressHold:
+        desiredGestures
+          ..add(GestureType.onTap)
+          ..add(GestureType.onLongPress)
+          ..add(GestureType.onDrag);
+        break;
+      case common.SelectionTrigger.hover:
+      default:
+        desiredGestures..add(GestureType.onHover);
+        break;
+    }
+    return desiredGestures;
+  }
+
+  @override
+  common.SelectNearest<D> createCommonBehavior() {
+    return new common.SelectNearest<D>(
+        selectionModelType: selectionModelType,
+        eventTrigger: eventTrigger,
+        selectionMode: selectionMode,
+        selectClosestSeries: selectClosestSeries,
+        maximumDomainDistancePx: maximumDomainDistancePx);
+  }
+
+  @override
+  void updateCommonBehavior(common.ChartBehavior commonBehavior) {}
+
+  // TODO: Explore the performance impact of calculating this once
+  // at the constructor for this and common ChartBehaviors.
+  @override
+  String get role => 'SelectNearest-${selectionModelType.toString()}}';
+
+  bool operator ==(Object other) {
+    if (other is SelectNearest) {
+      return (selectionModelType == other.selectionModelType) &&
+          (eventTrigger == other.eventTrigger) &&
+          (selectionMode == other.selectionMode) &&
+          (selectClosestSeries == other.selectClosestSeries) &&
+          (maximumDomainDistancePx == other.maximumDomainDistancePx);
+    } else {
+      return false;
+    }
+  }
+
+  int get hashCode {
+    int hashcode = selectionModelType.hashCode;
+    hashcode = hashcode * 37 + eventTrigger.hashCode;
+    hashcode = hashcode * 37 + selectionMode.hashCode;
+    hashcode = hashcode * 37 + selectClosestSeries.hashCode;
+    hashcode = hashcode * 37 + maximumDomainDistancePx.hashCode;
+    return hashcode;
+  }
+}