@tamagui/react-native-web-lite/src/vendor/react-native/TouchHistoryMath/index.js

React Native for Web

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 */

const TouchHistoryMath = {
  /**
   * This code is optimized and not intended to look beautiful. This allows
   * computing of touch centroids that have moved after `touchesChangedAfter`
   * timeStamp. You can compute the current centroid involving all touches
   * moves after `touchesChangedAfter`, or you can compute the previous
   * centroid of all touches that were moved after `touchesChangedAfter`.
   *
   * @param {TouchHistoryMath} touchHistory Standard Responder touch track
   * data.
   * @param {number} touchesChangedAfter timeStamp after which moved touches
   * are considered "actively moving" - not just "active".
   * @param {boolean} isXAxis Consider `x` dimension vs. `y` dimension.
   * @param {boolean} ofCurrent Compute current centroid for actively moving
   * touches vs. previous centroid of now actively moving touches.
   * @return {number} value of centroid in specified dimension.
   */
  centroidDimension: function (touchHistory, touchesChangedAfter, isXAxis, ofCurrent) {
    const touchBank = touchHistory.touchBank
    let total = 0
    let count = 0

    const oneTouchData =
      touchHistory.numberActiveTouches === 1
        ? touchHistory.touchBank[touchHistory.indexOfSingleActiveTouch]
        : null

    if (oneTouchData !== null) {
      if (
        oneTouchData.touchActive &&
        oneTouchData.currentTimeStamp > touchesChangedAfter
      ) {
        total +=
          ofCurrent && isXAxis
            ? oneTouchData.currentPageX
            : ofCurrent && !isXAxis
              ? oneTouchData.currentPageY
              : !ofCurrent && isXAxis
                ? oneTouchData.previousPageX
                : oneTouchData.previousPageY
        count = 1
      }
    } else {
      for (let i = 0; i < touchBank.length; i++) {
        const touchTrack = touchBank[i]
        if (
          touchTrack !== null &&
          touchTrack !== undefined &&
          touchTrack.touchActive &&
          touchTrack.currentTimeStamp >= touchesChangedAfter
        ) {
          let toAdd // Yuck, program temporarily in invalid state.
          if (ofCurrent && isXAxis) {
            toAdd = touchTrack.currentPageX
          } else if (ofCurrent && !isXAxis) {
            toAdd = touchTrack.currentPageY
          } else if (!ofCurrent && isXAxis) {
            toAdd = touchTrack.previousPageX
          } else {
            toAdd = touchTrack.previousPageY
          }
          total += toAdd
          count++
        }
      }
    }
    return count > 0 ? total / count : TouchHistoryMath.noCentroid
  },

  currentCentroidXOfTouchesChangedAfter: function (touchHistory, touchesChangedAfter) {
    return TouchHistoryMath.centroidDimension(
      touchHistory,
      touchesChangedAfter,
      true, // isXAxis
      true // ofCurrent
    )
  },

  currentCentroidYOfTouchesChangedAfter: function (touchHistory, touchesChangedAfter) {
    return TouchHistoryMath.centroidDimension(
      touchHistory,
      touchesChangedAfter,
      false, // isXAxis
      true // ofCurrent
    )
  },

  previousCentroidXOfTouchesChangedAfter: function (touchHistory, touchesChangedAfter) {
    return TouchHistoryMath.centroidDimension(
      touchHistory,
      touchesChangedAfter,
      true, // isXAxis
      false // ofCurrent
    )
  },

  previousCentroidYOfTouchesChangedAfter: function (touchHistory, touchesChangedAfter) {
    return TouchHistoryMath.centroidDimension(
      touchHistory,
      touchesChangedAfter,
      false, // isXAxis
      false // ofCurrent
    )
  },

  currentCentroidX: function (touchHistory) {
    return TouchHistoryMath.centroidDimension(
      touchHistory,
      0, // touchesChangedAfter
      true, // isXAxis
      true // ofCurrent
    )
  },

  currentCentroidY: function (touchHistory) {
    return TouchHistoryMath.centroidDimension(
      touchHistory,
      0, // touchesChangedAfter
      false, // isXAxis
      true // ofCurrent
    )
  },

  noCentroid: -1,
}

export { TouchHistoryMath }
export default TouchHistoryMath