34 lines
1.5 KiB
Plaintext
34 lines
1.5 KiB
Plaintext
var ds = function (ab) { return (ab[0] <= 0 && ab[1] >= 0) || (ab[0] >= 0 && ab[1] <= 0); };
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var sign = function (x) { return (x < 0 ? -1 : 1); };
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export var pinchOrZoom = function (event, cache) {
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if (!event.changedTouches) {
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return false;
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}
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if (event.touches.length === 2) {
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var oldPoints = [cache[event.touches[0].identifier], cache[event.touches[1].identifier]];
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var newPoints = [event.touches[0], event.touches[1]];
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if (oldPoints[0] && oldPoints[1]) {
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// Calculate the difference between the start and move coordinates
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var diffx = [oldPoints[0].clientX - newPoints[0].clientX, oldPoints[1].clientX - newPoints[1].clientX];
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var diffy = [oldPoints[0].clientY - newPoints[0].clientY, oldPoints[1].clientY - newPoints[1].clientY];
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console.log(diffx, diffy);
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if (ds(diffx) || ds(diffy)) {
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return {
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action: 'zoom',
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};
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}
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var mx = Math.max(Math.abs(diffx[0]), Math.abs(diffx[1]));
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var my = Math.max(Math.abs(diffy[0]), Math.abs(diffy[1]));
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return {
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action: 'pinch',
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coords: [mx * sign(diffx[0]), my * sign(diffx[1])],
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};
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}
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}
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Array.from(event.changedTouches).forEach(function (touch) { return (cache[touch.identifier] = touch); });
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return {
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action: 'move',
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coords: [event.changedTouches[0].clientX, event.changedTouches[0].clientY],
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};
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};
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