Infinite Loop and Autoplay Behavior Issue with 3 Items in Carousel

[PepeTonin]

Describe the bug
When using the carousel with infinite loop and autoplay enabled, the behavior is inconsistent for lists with 3 items. Specifically, the first item is not rendered correctly when reaching the end of the list, causing a noticeable delay and breaking the expected smooth transition. This issue does not occur with lists of 2 or 4 items, which work as expected.

Expected behavior
The carousel should smoothly transition from the last item back to the first item without any delay or rendering issues, just as it does with lists of 2 or 4 items.

Screenshots/Videos
I will link three videos in the issue:

• One showing the correct behavior with 2 items.

2.items.webm

• One showing the correct behavior with 4 items.

4.items.webm

• One showing the incorrect behavior with 3 items.

3.items.webm

Versions

• react: v18.3.1
• react-native: v0.76.7
• react-native-reanimated: v3.17.1
• react-native-reanimated-carousel: v4.0.2
• react-native-gesture-handler: v2.24.0

Smartphone

• Device: Pixel 8a API 35 (Android Emulator)
• OS: Android
• Browser: N/A (React Native)
• Version: N/A

Additional context

• My development environment is Windows 11.
• The project uses Expo SDK 52.

Temporary Workaround

• I duplicated the data when the list length is 3, but this feels like a hack and not a proper solution. It would be great to have a native fix for this issue.

Code to reproduce

import ReanimatedCarousel from "react-native-reanimated-carousel";
import { StyleProp, ViewStyle, Dimensions } from "react-native";
import { useEffect, useState } from "react";

const { width } = Dimensions.get("window");

interface CarouselProps<T> {
  data: T[];
  renderItem: (item: T, index: number) => JSX.Element;
  containerStyle?: StyleProp<ViewStyle>;
  carouselWindowHeight: number;
  carouselWindowWidth?: number;
  carouselItemWidth: number;
  marginBetweenItems?: number;
  infiniteLoopEnabled?: boolean;
  pagingEnabled?: boolean;
  snapEnabled?: boolean;
  autoPlayEnabled?: boolean;
  autoPlayInterval?: number;
}

export default function Carousel<T>({
  data,
  renderItem,
  containerStyle,
  carouselWindowHeight,
  carouselWindowWidth = width,
  carouselItemWidth,
  marginBetweenItems = 0,
  infiniteLoopEnabled = false,
  pagingEnabled = true,
  snapEnabled = true,
  autoPlayEnabled = false,
  autoPlayInterval = 2000,
}: CarouselProps<T>) {
  const getParallaxScrollingOffset =
    carouselWindowWidth - carouselItemWidth - marginBetweenItems;

  const [modifiedData, setModifiedData] = useState<T[]>(data);

  useEffect(() => {
    if (data.length === 3) {
      setModifiedData([...data, ...data]);
    }
  }, [data]);

  if (data.length <= 1) {
    return <></>;
  }

  return (
    <ReanimatedCarousel
      testID="reanimatedCarousel"
      width={carouselWindowWidth}
      height={carouselWindowHeight}
      pagingEnabled={pagingEnabled}
      snapEnabled={snapEnabled}
      autoPlay={autoPlayEnabled}
      loop={infiniteLoopEnabled}
      autoPlayInterval={autoPlayInterval}
      containerStyle={containerStyle}
      mode="parallax"
      modeConfig={{
        parallaxScrollingScale: 1,
        parallaxScrollingOffset: getParallaxScrollingOffset,
      }}
      onConfigurePanGesture={(panGestureHandlerProps) => {
        panGestureHandlerProps.activeOffsetX([-10, 10]);
      }}
      data={modifiedData}
      renderItem={({ item, index }) => renderItem(item, index)}
    />
  );
}

To Reproduce
Steps to reproduce the behavior:

1. Set up a carousel with infinite loop and autoplay enabled.
2. Use a data list with exactly 3 items.
3. Observe the carousel behavior when it reaches the end of the list.
4. Notice the delay and incorrect rendering of the first item.

[dosubot]

Hey there, @PepeTonin! 👋 I'm here to help you with any bugs, questions, or contributions you have in mind.

The issue you're experiencing with the react-native-reanimated-carousel when using a list of exactly 3 items, along with infinite loop and autoplay enabled, might be related to how the carousel handles the transition between the last and first items. When 'infiniteLoopEnabled' is set to true, the carousel should smoothly transition by wrapping around the items, but it seems there might be a specific edge case affecting lists with 3 items.

The workaround you've implemented by duplicating the data is a practical temporary solution, but it indeed feels like a hack. The underlying issue could be related to how the carousel calculates the visible ranges or manages the transition logic for small data sets.

To address this, you might want to explore the carousel's internal logic for handling visible ranges and transitions, especially focusing on how it calculates the negativeRange and positiveRange when 'infiniteLoopEnabled' is active. These ranges are crucial for maintaining the infinite loop effect by wrapping around the total number of items ^[1].

Additionally, ensure that the modeConfig settings, such as parallaxScrollingScale and parallaxScrollingOffset, are correctly configured to avoid any unintended visual effects during transitions ^[2][3][4][5].

If the issue persists, consider reviewing the carousel's source code or any recent changes in the library that might affect the rendering behavior for small data sets.

To continue talking to Dosu, mention @dosu.

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