@ionic/core
Version:
Base components for Ionic
52 lines (51 loc) • 1.39 kB
JavaScript
/*!
* (C) Ionic http://ionicframework.com - MIT License
*/
export const createPanRecognizer = (direction, thresh, maxAngle) => {
const radians = maxAngle * (Math.PI / 180);
const isDirX = direction === 'x';
const maxCosine = Math.cos(radians);
const threshold = thresh * thresh;
let startX = 0;
let startY = 0;
let dirty = false;
let isPan = 0;
return {
start(x, y) {
startX = x;
startY = y;
isPan = 0;
dirty = true;
},
detect(x, y) {
if (!dirty) {
return false;
}
const deltaX = x - startX;
const deltaY = y - startY;
const distance = deltaX * deltaX + deltaY * deltaY;
if (distance < threshold) {
return false;
}
const hypotenuse = Math.sqrt(distance);
const cosine = (isDirX ? deltaX : deltaY) / hypotenuse;
if (cosine > maxCosine) {
isPan = 1;
}
else if (cosine < -maxCosine) {
isPan = -1;
}
else {
isPan = 0;
}
dirty = false;
return true;
},
isGesture() {
return isPan !== 0;
},
getDirection() {
return isPan;
},
};
};