154 lines
4.2 KiB
JavaScript
154 lines
4.2 KiB
JavaScript
/**
|
|
* Copyright (c) Facebook, Inc. and its 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,
|
|
};
|
|
|
|
module.exports = TouchHistoryMath;
|