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CardStack.js
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CardStack.js
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/* @flow */
import React, { Component } from 'react';
import clamp from 'clamp';
import {
Animated,
StyleSheet,
PanResponder,
Platform,
View,
I18nManager,
Easing,
} from 'react-native';
import Card from './Card';
import Header from '../Header/Header';
import NavigationActions from '../../NavigationActions';
import addNavigationHelpers from '../../addNavigationHelpers';
import SceneView from '../SceneView';
import type {
NavigationAction,
NavigationLayout,
NavigationScreenProp,
NavigationScene,
NavigationRouter,
NavigationState,
NavigationScreenDetails,
NavigationStackScreenOptions,
HeaderMode,
ViewStyleProp,
TransitionConfig,
} from '../../TypeDefinition';
import TransitionConfigs from './TransitionConfigs';
const emptyFunction = () => {};
type Props = {
screenProps?: {},
headerMode: HeaderMode,
headerComponent?: ReactClass<*>,
mode: 'card' | 'modal',
navigation: NavigationScreenProp<NavigationState, NavigationAction>,
router: NavigationRouter<
NavigationState,
NavigationAction,
NavigationStackScreenOptions
>,
cardStyle?: ViewStyleProp,
onTransitionStart?: () => void,
onTransitionEnd?: () => void,
style?: any, // TODO: Remove
/**
* Optional custom animation when transitioning between screens.
*/
transitionConfig?: () => TransitionConfig,
// NavigationTransitionProps:
layout: NavigationLayout,
navigation: NavigationScreenProp<NavigationState, NavigationAction>,
position: Animated.Value,
progress: Animated.Value,
scenes: Array<NavigationScene>,
scene: NavigationScene,
index: number,
};
/**
* The max duration of the card animation in milliseconds after released gesture.
* The actual duration should be always less then that because the rest distance
* is always less then the full distance of the layout.
*/
const ANIMATION_DURATION = 500;
/**
* The gesture distance threshold to trigger the back behavior. For instance,
* `1/2` means that moving greater than 1/2 of the width of the screen will
* trigger a back action
*/
const POSITION_THRESHOLD = 1 / 2;
/**
* The threshold (in pixels) to start the gesture action.
*/
const RESPOND_THRESHOLD = 20;
/**
* The distance of touch start from the edge of the screen where the gesture will be recognized
*/
const GESTURE_RESPONSE_DISTANCE_HORIZONTAL = 25;
const GESTURE_RESPONSE_DISTANCE_VERTICAL = 135;
const animatedSubscribeValue = (animatedValue: Animated.Value) => {
if (!animatedValue.__isNative) {
return;
}
if (Object.keys(animatedValue._listeners).length === 0) {
animatedValue.addListener(emptyFunction);
}
};
class CardStack extends Component {
/**
* Used to identify the starting point of the position when the gesture starts, such that it can
* be updated according to its relative position. This means that a card can effectively be
* "caught"- If a gesture starts while a card is animating, the card does not jump into a
* corresponding location for the touch.
*/
_gestureStartValue: number = 0;
// tracks if a touch is currently happening
_isResponding: boolean = false;
/**
* immediateIndex is used to represent the expected index that we will be on after a
* transition. To achieve a smooth animation when swiping back, the action to go back
* doesn't actually fire until the transition completes. The immediateIndex is used during
* the transition so that gestures can be handled correctly. This is a work-around for
* cases when the user quickly swipes back several times.
*/
_immediateIndex: ?number = null;
_screenDetails: {
[key: string]: ?NavigationScreenDetails<NavigationStackScreenOptions>,
} = {};
props: Props;
componentWillReceiveProps(props: Props) {
if (props.screenProps !== this.props.screenProps) {
this._screenDetails = {};
}
props.scenes.forEach((newScene: *) => {
if (
this._screenDetails[newScene.key] &&
this._screenDetails[newScene.key].state !== newScene.route
) {
this._screenDetails[newScene.key] = null;
}
});
}
_getScreenDetails = (scene: NavigationScene): NavigationScreenDetails<*> => {
const { screenProps, navigation, router } = this.props;
let screenDetails = this._screenDetails[scene.key];
if (!screenDetails || screenDetails.state !== scene.route) {
const screenNavigation = addNavigationHelpers({
...navigation,
state: scene.route,
});
screenDetails = {
state: scene.route,
navigation: screenNavigation,
options: router.getScreenOptions(screenNavigation, screenProps),
};
this._screenDetails[scene.key] = screenDetails;
}
return screenDetails;
};
_renderHeader(
scene: NavigationScene,
headerMode: HeaderMode
): ?React.Element<*> {
const { header } = this._getScreenDetails(scene).options;
if (typeof header !== 'undefined' && typeof header !== 'function') {
return header;
}
const renderHeader = header || ((props: *) => <Header {...props} />);
// We need to explicitly exclude `mode` since Flow doesn't see
// mode: headerMode override below and reports prop mismatch
const { mode, ...passProps } = this.props;
return renderHeader({
...passProps,
scene,
mode: headerMode,
getScreenDetails: this._getScreenDetails,
});
}
// eslint-disable-next-line class-methods-use-this
_animatedSubscribe(props: Props) {
// Hack to make this work with native driven animations. We add a single listener
// so the JS value of the following animated values gets updated. We rely on
// some Animated private APIs and not doing so would require using a bunch of
// value listeners but we'd have to remove them to not leak and I'm not sure
// when we'd do that with the current structure we have. `stopAnimation` callback
// is also broken with native animated values that have no listeners so if we
// want to remove this we have to fix this too.
animatedSubscribeValue(props.layout.width);
animatedSubscribeValue(props.layout.height);
animatedSubscribeValue(props.position);
}
_reset(resetToIndex: number, duration: number): void {
Animated.timing(this.props.position, {
toValue: resetToIndex,
duration,
easing: Easing.linear(),
useNativeDriver: this.props.position.__isNative,
}).start();
}
_goBack(backFromIndex: number, duration: number) {
const { navigation, position, scenes } = this.props;
const toValue = Math.max(backFromIndex - 1, 0);
// set temporary index for gesture handler to respect until the action is
// dispatched at the end of the transition.
this._immediateIndex = toValue;
Animated.timing(position, {
toValue,
duration,
easing: Easing.linear(),
useNativeDriver: position.__isNative,
}).start(() => {
this._immediateIndex = null;
const backFromScene = scenes.find((s: *) => s.index === toValue + 1);
if (!this._isResponding && backFromScene) {
navigation.dispatch(
NavigationActions.back({ key: backFromScene.route.key })
);
}
});
}
render(): React.Element<*> {
let floatingHeader = null;
const headerMode = this._getHeaderMode();
if (headerMode === 'float') {
floatingHeader = this._renderHeader(this.props.scene, headerMode);
}
const { navigation, position, layout, scene, scenes, mode } = this.props;
const { index } = navigation.state;
const isVertical = mode === 'modal';
const responder = PanResponder.create({
onPanResponderTerminate: () => {
this._isResponding = false;
this._reset(index, 0);
},
onPanResponderGrant: () => {
position.stopAnimation((value: number) => {
this._isResponding = true;
this._gestureStartValue = value;
});
},
onMoveShouldSetPanResponder: (
event: { nativeEvent: { pageY: number, pageX: number } },
gesture: any
) => {
if (index !== scene.index) {
return false;
}
const immediateIndex =
this._immediateIndex == null ? index : this._immediateIndex;
const currentDragDistance = gesture[isVertical ? 'dy' : 'dx'];
const currentDragPosition =
event.nativeEvent[isVertical ? 'pageY' : 'pageX'];
const axisLength = isVertical
? layout.height.__getValue()
: layout.width.__getValue();
const axisHasBeenMeasured = !!axisLength;
// Measure the distance from the touch to the edge of the screen
const screenEdgeDistance = currentDragPosition - currentDragDistance;
// Compare to the gesture distance relavant to card or modal
const {
gestureResponseDistance: userGestureResponseDistance = {},
} = this._getScreenDetails(scene).options;
const gestureResponseDistance = isVertical
? userGestureResponseDistance.vertical ||
GESTURE_RESPONSE_DISTANCE_VERTICAL
: userGestureResponseDistance.horizontal ||
GESTURE_RESPONSE_DISTANCE_HORIZONTAL;
// GESTURE_RESPONSE_DISTANCE is about 25 or 30. Or 135 for modals
if (screenEdgeDistance > gestureResponseDistance) {
// Reject touches that started in the middle of the screen
return false;
}
const hasDraggedEnough =
Math.abs(currentDragDistance) > RESPOND_THRESHOLD;
const isOnFirstCard = immediateIndex === 0;
const shouldSetResponder =
hasDraggedEnough && axisHasBeenMeasured && !isOnFirstCard;
return shouldSetResponder;
},
onPanResponderMove: (event: any, gesture: any) => {
// Handle the moving touches for our granted responder
const startValue = this._gestureStartValue;
const axis = isVertical ? 'dy' : 'dx';
const axisDistance = isVertical
? layout.height.__getValue()
: layout.width.__getValue();
const currentValue =
I18nManager.isRTL && axis === 'dx'
? startValue + gesture[axis] / axisDistance
: startValue - gesture[axis] / axisDistance;
const value = clamp(index - 1, currentValue, index);
position.setValue(value);
},
onPanResponderTerminationRequest: () =>
// Returning false will prevent other views from becoming responder while
// the navigation view is the responder (mid-gesture)
false,
onPanResponderRelease: (event: any, gesture: any) => {
if (!this._isResponding) {
return;
}
this._isResponding = false;
const immediateIndex =
this._immediateIndex == null ? index : this._immediateIndex;
// Calculate animate duration according to gesture speed and moved distance
const axisDistance = isVertical
? layout.height.__getValue()
: layout.width.__getValue();
const movedDistance = gesture[isVertical ? 'dy' : 'dx'];
const gestureVelocity = gesture[isVertical ? 'vy' : 'vx'];
const defaultVelocity = axisDistance / ANIMATION_DURATION;
const velocity = Math.max(Math.abs(gestureVelocity), defaultVelocity);
const resetDuration = movedDistance / velocity;
const goBackDuration = (axisDistance - movedDistance) / velocity;
// To asyncronously get the current animated value, we need to run stopAnimation:
position.stopAnimation((value: number) => {
// If the speed of the gesture release is significant, use that as the indication
// of intent
if (gestureVelocity < -0.5) {
this._reset(immediateIndex, resetDuration);
return;
}
if (gestureVelocity > 0.5) {
this._goBack(immediateIndex, goBackDuration);
return;
}
// Then filter based on the distance the screen was moved. Over a third of the way swiped,
// and the back will happen.
if (value <= index - POSITION_THRESHOLD) {
this._goBack(immediateIndex, goBackDuration);
} else {
this._reset(immediateIndex, resetDuration);
}
});
},
});
const { options } = this._getScreenDetails(scene);
const gesturesEnabled =
typeof options.gesturesEnabled === 'boolean'
? options.gesturesEnabled
: Platform.OS === 'ios';
const handlers = gesturesEnabled ? responder.panHandlers : {};
const containerStyle = [
styles.container,
this._getTransitionConfig().containerStyle,
];
return (
<View {...handlers} style={containerStyle}>
<View style={styles.scenes}>
{scenes.map((s: *) => this._renderCard(s))}
</View>
{floatingHeader}
</View>
);
}
_getHeaderMode(): HeaderMode {
if (this.props.headerMode) {
return this.props.headerMode;
}
if (Platform.OS === 'android' || this.props.mode === 'modal') {
return 'screen';
}
return 'float';
}
_renderInnerScene(
SceneComponent: ReactClass<*>,
scene: NavigationScene
): React.Element<any> {
const { navigation } = this._getScreenDetails(scene);
const { screenProps } = this.props;
const headerMode = this._getHeaderMode();
if (headerMode === 'screen') {
return (
<View style={styles.container}>
<View style={{ flex: 1 }}>
<SceneView
screenProps={screenProps}
navigation={navigation}
component={SceneComponent}
/>
</View>
{this._renderHeader(scene, headerMode)}
</View>
);
}
return (
<SceneView
screenProps={this.props.screenProps}
navigation={navigation}
component={SceneComponent}
/>
);
}
_getTransitionConfig = () => {
const isModal = this.props.mode === 'modal';
/* $FlowFixMe */
return TransitionConfigs.getTransitionConfig(
this.props.transitionConfig,
{},
{},
isModal
);
};
_renderCard = (scene: NavigationScene): React.Element<*> => {
const { screenInterpolator } = this._getTransitionConfig();
const style =
screenInterpolator && screenInterpolator({ ...this.props, scene });
const SceneComponent = this.props.router.getComponentForRouteName(
scene.route.routeName
);
return (
<Card
{...this.props}
key={`card_${scene.key}`}
style={[style, this.props.cardStyle]}
scene={scene}
>
{this._renderInnerScene(SceneComponent, scene)}
</Card>
);
};
}
const styles = StyleSheet.create({
container: {
flex: 1,
// Header is physically rendered after scenes so that Header won't be
// covered by the shadows of the scenes.
// That said, we'd have use `flexDirection: 'column-reverse'` to move
// Header above the scenes.
flexDirection: 'column-reverse',
},
scenes: {
flex: 1,
},
});
export default CardStack;