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/**
*/
'use strict';
var 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) {
var touchBank = touchHistory.touchBank;
var total = 0;
var count = 0;
var 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 (var i = 0; i < touchBank.length; i++) {
var touchTrack = touchBank[i];
if (touchTrack !== null && touchTrack !== undefined && touchTrack.touchActive && touchTrack.currentTimeStamp >= touchesChangedAfter) {
var 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;
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