When i drag and release finger , flatlist will glide automatically for a while.
I want disable the auto inertia glide,it means :
after release finger, flatlist stops scrolling at once.
How to do with flatlist?
Thanks!
<FlatList
...
decelerationRate="fast"
...
/>
Scrolling will degrade much faster than normal which kind of give the feeling of no momentum.
Set the decelerationRate property to {0}.
For example:
<FlatList
...
decelerationRate={0}
...
/>
Related
I want to stop a ScrollView from scrolling in React Native. I don't want to completely disable it, I just want it to stop scrolling at a specific point, so that I can scroll it again afterwards.
Since the scrolling momentum still persists afterwards, I can't simply disable it when a certain condition is met, so the following code does not work.
<ScrollView
onScroll={e => {
if (e.nativeEvent.contentOffset.y > 500) {
setStopScroll(true)
}
}}
scrollEnabled={!stopScroll}
/>
I omitted the part in which is enabled the scroll view again to continue scrolling.
You are looking for snapToOffsets. This takes an array of positions where you want it to stop. After it stops, if you scroll again, it will stop at the next offset. Also make sure snapToEnd is set to false.
<ScrollView
snapToOffsets={[100,500,800]}
decelerationRate="fast"
snapToEnd={false}
snapToStart={false}
disableIntervalMomentum={true}
onScroll={onScroll}
>
... your code here
</ScrollView>
I have a ScrollView containing several graphs made with react-native-skia. The graphs are interactable, i.e. I can touch them and move an indicator on the graph along the x-axis of the graph.
My issue is that the whenever the ScrollView events fire (i.e. we scroll up/down), then the graph touch events are ignored which makes for bad UX.
Demo:
Here's a Snack with a reproducible demo: https://snack.expo.dev/#jorundur/supportive-raisins
FYI: For some reason for me the Canvas disappears after 1 second in the Snack, but if you make any change in the file and save (such add a newline somewhere), then it appears. It's fine if you run this locally. But that's some other problem we can ignore for the purpose of this discussion.
Description:
The demo is a react-native ScrollView large enough to make sure we have to scroll, the top component is a graph using react-native-skia. If we drag the cursor in the graph around, then the UX gets bad pretty quickly as the graph touch events seem to be ignored as soon as any vertical scrolling happens. I've tried playing around with ScrollView from react-native-gesture-handler but without luck.
To me, the expected behaviour would be for the graph to be interactable even while scrolling. I.e. if I'm pressing the graph and move my finger diagonally up/down I would expect the ScrollView to scroll and the graph cursor also to change its position accordingly. (I say diagonally since a straight vertical movement wouldn't change the cursor position in this graph.)
Much appreciated if anyone has any ideas on how to solve this! I couldn't work out how to do it via GestureDetector from react-native-gesture-handler like I've heard suggested.
Possible solution (?):
What I think I need to do is remove the onTouch={touchHandler} which I'm using currently in the react-native-skia Canvas component and instead get those touches via gesture detection from react-native-gesture-handler. I then need to make those gestures work simultaneously with the parent ScrollViews scroll event gestures. I've not had any luck implementing that unfortunately.
The solution was to do the following:
Don't use onTouch on Canvas, instead detect gestures via react-native-gesture-handler
Create a gesture and add a ref to it
Add the simultaneousHandlers prop to the ScrollView and use the ref there
This tells the ScrollView that its events should not be blocked by the touch events from the ref
To reiterate, what I wanted to do was to have the touch events of a ScrollView work simultaneously with touch events from a react-native-skia Canvas child component.
Code (relevant bits):
import * as React from 'react';
import {
GestureHandlerRootView,
ScrollView // Note that this is not imported from react-native
} from 'react-native-gesture-handler';
const App = () => {
// Create ref for the ScrollView to know what other gestures it should work simultaneously with.
// My use case required pan but this can be swapped for other gestures.
const panGestureRef = React.useRef<GestureType>(Gesture.Pan());
// The logic that used to be in `onTouch` on the Canvas is now here
const panGesture = Gesture.Pan()
.onChange((e) => {
// Do stuff, also use the other callbacks available as needed
})
.withRef(panGestureRef);
return (
<GestureHandlerRootView style={{ flex: 1 }}>{/* Don't forget this! It should be at the root of your project. */}
<ScrollView simultaneousHandlers={[panGestureRef]}>
<GestureDetector gesture={panGesture}>
<Canvas style={{ width: 200, height: 200 }}>
{/* Your interactive react-native-skia magic */}
</Canvas>
</GestureDetector>
</ScrollView>
</GestureHandlerRootView>
);
};
export default App;
I have a Flatlist inside a ScrollView with 100 items, but no matter what height I give to the ScrollView or Flatlist, there are always just 18 items displayed on my Phone. After that the slider of the ScrollView is still scrolling down, but the list ends after 18 items. I want to be able to scroll through the complete list of items with the ScrollView containing the FlatList. I am using a Samsung Galaxy S8+ as a test device.
Here is a snack of the problem: https://snack.expo.io/#christophhummler/stickyheaderscrollscreens
Thanks for your help :)
I think it has to do with the scrollEnabled={false}, set it to true or remove the prop altogether otherwise it may be your todos array
Edit
Since you want to create a sticky header you must set the height to be the device height of screen + height of header, change styles.scrollView to :
scrollView: {
height: height + 200,
}
also on android there is an issue of nesting scrollviews, to enable a nested scrollview add the nestedScrollEnabled prop:
<FlatList
...
nestedScrollEnabled={true}
/>
You will have to implement logic to enable the Flatlist scroll view when the specific threshholds are met. It works at the moment in conjunction with scrollEnabled={true}
i hope this helps
I have a component which when the user long press a card I show a bigger version of this card.
The ideia is that the bigger card will be shown as long as the user keep pressing the touch and then will hide only when the finger is released (something like instagram long press). I tried to archieve this using the onLongPress and the onPressOut props of <TouchableHighlight>, the thing is that the onPressOut props has something that they call "cancel",
/**
* Called when the touch is released,
* but not if cancelled (e.g. by a scroll that steals the responder lock).
*/
What is happening is that when the user hold and move the finger the onPressOut prop is called, therefore the bigger card is hidden.
This is the code:
<View style={styles.container}>
<View style={styles.separator}>
<TouchableHighlight
underlayColor="rgba(255, 255, 255, 0)"
onPress={this.cardClick}
onLongPress={this.cardLongPress}
onPressOut={this.cardPressOut}
>
{this.content}
</TouchableHighlight>
</View>
</View>
Here is a GIF to show what is happening:
GIF
What I want is something that is only triggered when the user acctually releases his finger, regardless of whether or not he is moving the finger arround. Thanks in advance for the help.
Try setting an offset https://facebook.github.io/react-native/docs/touchablewithoutfeedback#pressretentionoffset , or convert your root view in a touchablewithoutfeedback, and call onPressOut there
So you want an Instagram style preview modal. I got you.
As mentioned in previous comments, you should use the pressRetentionOffset prop that will let you "extend" the pressable area. https://facebook.github.io/react-native/docs/touchablewithoutfeedback#pressretentionoffset
But! this prop will only work if the ScrollView is disabled. so you will need to disable the scrolling when the preview modal is shown.
You can do that with the scrollEnabled prop on ScrollView and make it falsy when the preview modal is shown.
Of course, this works with onLongPress and onPressOut props.
I am using <FlatList> to render a list:
<FlatList
ListFooterComponent={this.renderFooter}
ItemSeparatorComponent={this.renderSeparator}
refreshing={this.state.refreshing}
onRefresh={this.doPullRefresh}
onEndReached={this.endFooter}
initialNumToRender={10}
onEndReachedThreshold={0.5}
removeClippedSubviews={false}
data={this.state.listdata}
renderItem={({item}) => <ListItem onPress={this.goToStuInfo} alldata={item} id={item.key} number={item.number} avatar={item.avatar} name={item.name} />}
/>
The total size of data is about 300. So I can see some data is displayed while other data is being rendered as a list item.
At this moment(some data is still being rendered), if I touch an item, there will be a delay. I have to wait for a long time to get the response. And I have to wait even when I press the Back button.
Is there any solution that the list can response my touch movement first?
My Solution
Well, I solved this problem by render 10 items once.
I will push more data to this.state.listdata in onEndReached
Works for me.
are props change when ya touch items ?? 300 list elements not the big deal
"Limiting the render window also reduces the amount of work that needs to be done by React and the native platform, e.g from view traversals. Even if you are rendering the last of a million elements, with these new lists there is no need to iterate through all those elements in order to render. You can even jump to the middle with scrollToIndex without excessive rendering."