Clean up NavigationAnimatedView

Summary:- Add flow type checks.
- Fix code styles.
- Improve the logics to update `this.state.scenes`.
- Improve the logics to pass the layout.

Reviewed By: ericvicenti

Differential Revision: D3022107

fb-gh-sync-id: 23f4ed22db797f68bde0ba4f3cdd123701934fc3
shipit-source-id: 23f4ed22db797f68bde0ba4f3cdd123701934fc3

Libraries/NavigationExperimental/NavigationAnimatedView.js

@@ -21,9 +21,11 @@ const View = require('View');
 import type {
   NavigationAnimatedValue,
   NavigationAnimationSetter,
+  NavigationLayout,
   NavigationParentState,
   NavigationScene,
   NavigationSceneRenderer,
+  NavigationState,
 } from 'NavigationTypeDefinition';
 
 /**
@@ -102,71 +104,87 @@ const defaultProps = {
 class NavigationAnimatedView
   extends React.Component<any, Props, State> {
 
-  _animatedHeight: Animated.Value;
-  _animatedWidth: Animated.Value;
-  _lastHeight: number;
-  _lastWidth: number;
+  _layout: NavigationLayout;
+  _onLayout: (event: any) => void;
+  _onProgressChange: (data: {value: number}) => void;
   _positionListener: any;
 
   props: Props;
   state: State;
 
-  constructor(props) {
-    super(props);
-    this._lastWidth = 0;
-    this._lastHeight = 0;
-    this._animatedHeight = new Animated.Value(this._lastHeight);
-    this._animatedWidth = new Animated.Value(this._lastWidth);
+  constructor(props: Props, context: any) {
+    super(props, context);
+
+    this._layout = {
+      initWidth: 0,
+      initHeight: 0,
+      width: new Animated.Value(0),
+      height: new Animated.Value(0),
+    };
 
     this.state = {
       position: new Animated.Value(this.props.navigationState.index),
-      scenes: [],
+      scenes: this._reduceScenes([], this.props.navigationState),
     };
   }
-  componentWillMount() {
-    this.setState({
-      scenes: this._reduceScenes(this.state.scenes, this.props.navigationState),
-    });
+
+  componentWillMount(): void {
+    this._onLayout = this._onLayout.bind(this);
+    this._onProgressChange = this._onProgressChange.bind(this);
   }
-  componentDidMount() {
-    this._positionListener = this.state.position.addListener(this._onProgressChange.bind(this));
+
+  componentDidMount(): void {
+    this._positionListener =
+      this.state.position.addListener(this._onProgressChange);
   }
-  componentWillReceiveProps(nextProps) {
+
+  componentWillReceiveProps(nextProps: Props): void {
     if (nextProps.navigationState !== this.props.navigationState) {
       this.setState({
-        scenes: this._reduceScenes(this.state.scenes, nextProps.navigationState, this.props.navigationState),
+        scenes: this._reduceScenes(
+          this.state.scenes,
+          nextProps.navigationState,
+          this.props.navigationState
+        ),
       });
     }
   }
-  componentDidUpdate(lastProps) {
-    if (lastProps.navigationState.index !== this.props.navigationState.index && this.props.setTiming) {
-      this.props.setTiming(this.state.position, this.props.navigationState, lastProps.navigationState);
+
+  componentDidUpdate(lastProps: Props): void {
+    if (lastProps.navigationState.index !== this.props.navigationState.index) {
+      this.props.setTiming(
+        this.state.position,
+        this.props.navigationState,
+        lastProps.navigationState
+      );
     }
   }
-  componentWillUnmount() {
-    if (this._positionListener) {
-      this.state.position.removeListener(this._positionListener);
-      this._positionListener = null;
-    }
+
+  componentWillUnmount(): void {
+    this.state.position.removeListener(this._positionListener);
   }
+
   _onProgressChange(data: Object): void {
-    if (Math.abs(data.value - this.props.navigationState.index) > Number.EPSILON) {
+    const delta = Math.abs(data.value - this.props.navigationState.index);
+    if (delta > Number.EPSILON) {
       return;
     }
-    this.state.scenes.forEach((scene, index) => {
-      if (scene.isStale) {
-        const scenes = this.state.scenes.slice();
-        scenes.splice(index, 1);
-        this.setState({ scenes, });
-      }
+
+    const scenes = this.state.scenes.filter(scene => {
+      return !scene.isStale;
     });
+
+    if (scenes.length !== this.state.scenes.length) {
+      this.setState({ scenes });
+    }
   }
+
   _reduceScenes(
     scenes: Array<NavigationScene>,
     nextState: NavigationParentState,
     lastState: ?NavigationParentState
   ): Array<NavigationScene> {
-    let nextScenes = nextState.children.map((child, index) => {
+    const nextScenes = nextState.children.map((child, index) => {
       return {
         index,
         isStale: false,
@@ -175,8 +193,11 @@ class NavigationAnimatedView
     });
 
     if (lastState) {
-      lastState.children.forEach((child, index) => {
-        if (!NavigationStateUtils.get(nextState, child.key) && index !== nextState.index) {
+      lastState.children.forEach((child: NavigationState, index: number) => {
+        if (
+          !NavigationStateUtils.get(nextState, child.key) &&
+          index !== nextState.index
+        ) {
           nextScenes.push({
             index,
             isStale: true,
@@ -186,38 +207,21 @@ class NavigationAnimatedView
       });
     }
 
-    nextScenes = nextScenes.sort(compareScenes);
-
-    return nextScenes;
+    return nextScenes.sort(compareScenes);
   }
-  render() {
+
+  render(): ReactElement {
     return (
       <View
-        onLayout={(e) => {
-          const {height, width} = e.nativeEvent.layout;
-          this._animatedHeight &&
-            this._animatedHeight.setValue(height);
-          this._animatedWidth &&
-            this._animatedWidth.setValue(width);
-          this._lastHeight = height;
-          this._lastWidth = width;
-        }}
+        onLayout={this._onLayout}
         style={this.props.style}>
         {this.state.scenes.map(this._renderScene, this)}
         {this._renderOverlay()}
       </View>
     );
   }
-  _getLayout() {
-    return {
-      height: this._animatedHeight,
-      width: this._animatedWidth,
-      initWidth: this._lastWidth,
-      initHeight: this._lastHeight,
-    };
-  }
 
-  _renderScene(scene: NavigationScene) {
+  _renderScene(scene: NavigationScene): ?ReactElement {
     const {
       navigationState,
       onNavigate,
@@ -230,7 +234,7 @@ class NavigationAnimatedView
     } = this.state;
 
     return renderScene({
-      layout: this._getLayout(),
+      layout: this._layout,
       navigationState,
       onNavigate,
       position,
@@ -239,7 +243,7 @@ class NavigationAnimatedView
     });
   }
 
-  _renderOverlay() {
+  _renderOverlay(): ?ReactElement {
     if (this.props.renderOverlay) {
       const {
         navigationState,
@@ -253,7 +257,7 @@ class NavigationAnimatedView
       } = this.state;
 
       return renderOverlay({
-        layout: this._getLayout(),
+        layout: this._layout,
         navigationState,
         onNavigate,
         position,
@@ -263,6 +267,21 @@ class NavigationAnimatedView
     }
     return null;
   }
+
+  _onLayout(event: any): void {
+    const {height, width} = event.nativeEvent.layout;
+
+    const layout = {
+      ...this._layout,
+      initHeight: height,
+      initWidth: width,
+    };
+
+    this._layout = layout;
+
+    layout.height.setValue(height);
+    layout.width.setValue(width);
+  }
 }
 
 NavigationAnimatedView.propTypes = propTypes;