@jamsch/react-native-duo-drag-drop

Duolingo-style drag and drop for React Native using react-native-gesture-handler & react-native-reanimated. This library is heavily inspired by the work done by William Candillon in his video: Duolingo Drag-and-drop - "Can it be done in React Native?"

Prerequisites

Please make sure you have the the following dependencies installed in your project before continuing:

• react-native ^0.68.2
• react-native-reanimated ^2.8.0
• react-native-gesture-handler ^2.2.1

For projects using react-native-gesture-handler@v1, you can use @jamsch/[email protected]

Installation

npm install @jamsch/react-native-duo-drag-drop

Basic Usage

import { GestureHandlerRootView } from "react-native-gesture-handler";
import DuoDragDrop from "@jamsch/react-native-duo-drag-drop";

function App() {
  return (
    <GestureHandlerRootView style={{ flex: 1 }}>
      <View style={{ margin: 20 }}>
        <DuoDragDrop words={["Juan", "She", "apples", "today", "with", "eats", "her", "another"]} />
      </View>
    </GestureHandlerRootView>
  );
}

export default App;

DuoDragDrop props

interface DuoDragDropProps {
  /** List of words that will be used for the drag-and-drop  */
  words: string[];
  /** Re-renders the words when this value changes. */
  extraData?: any;
  /** Height of an individual word. Default: 45 */
  wordHeight?: number;
  /** The gap between each word / line: Default: 4 */
  wordGap?: number;
  /** The height of a single line in the top "answered" pile. Default: wordHeight * 1.2  */
  lineHeight?: number;
  /** The margin between the "Bank" pile and the "Answer" pile. Default: 20 */
  wordBankOffsetY?: number;
  /** Whether to lay out words in the "Answer" pile from right-to-left (for languages such as Arabic) */
  rtl?: boolean;
  /** Whether tap & drag gestures are disabled. Default: false */
  gesturesDisabled?: boolean;
  /** The offset between the "Bank" pile and the "Answer" pile. Default: 20 */
  wordBankAlignment?: "center" | "left" | "right";
  /** Overrides the default Word renderer */
  renderWord?: (word: string, index: number) => JSX.Element;
  /** Overrides the default Lines renderer */
  renderLines?: (props: { numLines: number; containerHeight: number; lineHeight: number }) => JSX.Element;
  /** Overrides the default Placeholder renderer */
  renderPlaceholder?:
    | ((props: {
        style: {
          position: "absolute";
          height: number;
          top: number;
          left: number;
          width: number;
        };
      }) => JSX.Element)
    | null;
  /** Allows user to modify animation of the word while it's animating. NOTE: this must be a worklet */
  animatedStyleWorklet?: DuoAnimatedStyleWorklet;
  /** Runs when the drag-and-drop has rendered */
  onReady?: (ready: boolean) => void;
  /** Called when a user taps or drags a word to its destination */
  onDrop?: (event: { index: number; destination: "answered" | "bank"; position: number }) => void;
}

DuoDragDrop ref value

/** Returns an ordered list of words that are in the "word bank" as well as answered */
getWords(): { answered: string[]; bank: string[] };
/** Returns an array of words that are outside the "word bank" */
getAnsweredWords(): string[];
/**
* Gets the order value of each word by the word's index.
* -1 indicates that it's in the "bank"
*
* e.g. ["hello", "world", "foo", "bar"] -> [1, -1, 0, 2] corresponds to:
* - ["hello", "foo", "bar"] (unordered) or
* - ["foo", "hello", "bar"] (ordered) in the "answered" pile
* - and ["world"] in the "bank" pile
*/
getOffsets(): number[];
/* Animates the word buttons to move to new positions */
setOffsets(newOffsets: number[]): void;

Fetching words in the "bank" or "answered" pile

You can use refs to find whether words are in the "answered" pile or in the "bank".

As a reference, the "word bank" is the list of words at the bottom, and the "answered" words are the list of words the user has dragged up in to the lines.

import { GestureHandlerRootView } from "react-native-gesture-handler";
import DuoDragDrop, { DuoDragDropRef } from "@jamsch/react-native-duo-drag-drop";

function App() {
  const ref = useRef<DuoDragDropRef>(null);

  return (
    <GestureHandlerRootView style={{ flex: 1 }}>
      <View style={{ margin: 20, minHeight: 300 }}>
        <DuoDragDrop ref={ref} words={["Juan", "She", "apples", "today", "with", "eats", "her", "another"]} />
      </View>
      <Button
        title="Get words"
        onPress={() => {
          const answered = ref.current?.getAnsweredWords();
          console.log(answered); // ["Juan", "She"]
          const words = ref.current?.getWords();
          console.log(words); // { answered: ["Juan", "She"], bank: ["today", "with", ...] }
        }}
      />
    </GestureHandlerRootView>
  );
}

export default App;

Customising Words/Lines/Placeholders

You can either customise the default "Word"/"Lines"/"Placeholder" components or provide your own components. For example:

import DuoDragDrop, { Word, Lines, Placeholder } from "@jamsch/react-native-duo-drag-drop";

function DndExample() {
  return (
    <DuoDragDrop
      words={["Juan", "She", "apples", "today", "with", "eats", "her", "another"]}
      renderWord={(word, index) => (
        <Word
          containerStyle={{
            backgroundColor: "teal",
          }}
          textStyle={{
            color: index % 2 === 0 ? "white" : "black",
          }}
        />
      )}
      // Change the border radius of the default Placeholder
      renderPlaceholder={({ style }) => <Placeholder style={[style, { borderRadius: 5 }]} />}
      // Modify the container/line style of Lines.
      renderLines={(props) => (
        <Lines {...props} containerStyle={{ backgroundColor: "transparent" }} lineStyle={{ borderColor: "#CCC" }} />
      )}
    />
  );
}

Customising animations

You can customise how the words are animated by providing a worklet function.

import DuoDragDrop, { DuoAnimatedStyleWorklet } from "@jamsch/react-native-duo-drag-drop";
import { withTiming, withSpring } from "react-native-reanimated";

const customAnimatedStyle: DuoAnimatedStyleWorklet = (style, isGestureActive) => {
  "worklet";
  // Scale the word when the gesture is active
  style.transform.push({
    scale: withTiming(isGestureActive ? 1.5 : 1, { duration: 250 }),
  });
  style.opacity = withTiming(isGestureActive ? 0.8 : 1, { duration: 250 });
  style.top = withTiming(isGestureActive ? -10 : 0, { duration: 250 });

  // Apply a spring when the word moves to it's destination
  if (!isGestureActive) {
    style.transform[0].translateX = withSpring(style.transform[0].translateX);
    style.transform[1].translateY = withSpring(style.transform[1].translateY);
  }

  return style;
};

export default function DragDrop() {
  return (
    <DuoDragDrop
      words={["Juan", "She", "apples", "today", "with", "eats", "her", "another"]}
      animatedStyleWorklet={customAnimatedStyle}
    />
  );
}

Contributing

See the contributing guide to learn how to contribute to the repository and the development workflow.

License

MIT