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ioneapps-maagapp-ee31119a522d/scripts/react-native-largelist-v3/Group.js

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+/*
+ *
+ * Created by Stone
+ * Email: shanshang130@gmail.com
+ * Date: 2018/7/17
+ *
+ */
+
+import React from "react";
+import { StyleSheet } from "react-native";
+import type { GroupPropType } from "./Types";
+
+export class Group extends React.Component<GroupPropType> {
+  _currentIndex = 0;
+  _offset = 0;
+  _margin = 0;
+
+  constructor(props) {
+    super(props);
+    if (props.initialContentOffset) {
+      this.contentConversion(props.initialContentOffset.y, true);
+    }
+  }
+
+  contentConversion(offset: number, init: boolean = false) {
+    this._offset = offset;
+    const { input, output } = this.props;
+    const cc = [];
+    output.forEach(v => cc.indexOf(v) < 0 && cc.push(v));
+    for (let i = 0; i < input.length; ++i) {
+      if (offset >= input[i] && offset <= input[i + 1]) {
+        this.update(cc.indexOf(output[i]), init);
+        break;
+      }
+    }
+  }
+
+  update(index: number, init: boolean) {
+    if (index < 0 || index >= this.props.indexes.length || this._currentIndex === index) return;
+    this._currentIndex = index;
+    !init && this.forceUpdate();
+  }
+
+  UNSAFE_componentWillReceiveProps(next: GroupPropType) {
+    if (next.offset) {
+      this._offset = null;
+      this.contentConversion(next.offset);
+    }
+  }
+
+  render() {
+    const { indexes, heightForSection, heightForIndexPath, renderIndexPath, inverted } = this.props;
+    if (this._currentIndex >= indexes.length) return null;
+    this._margin = 0;
+    return indexes[this._currentIndex].map((indexPath, index) => {
+      if (indexPath.row === -1) {
+        this._margin = this._margin + heightForSection(indexPath.section);
+        return null;
+      }
+      const height = heightForIndexPath(indexPath);
+      if (height === 0) return null;
+      const cell = React.Children.only(renderIndexPath(indexPath));
+      const marginTop = this._margin;
+      this._margin = 0;
+      const style = StyleSheet.flatten([
+        cell.props.style,
+        {
+          height,
+          marginTop,
+          alignSelf: "stretch",
+          flex: 0,
+          transform: [{ scaleY: inverted ? -1 : 1 }]
+        }
+      ]);
+      const key = cell.props.key ? cell.props.key : index;
+      return React.cloneElement(cell, {
+        key,
+        style
+      });
+    });
+  }
+}