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