sard-uniapp/use/useInitialVelocity.js

sard-uniapp 是一套基于 Uniapp + Vue3 框架开发的兼容多端的 UI 组件库

export function useInitialVelocity() {
    const touchInfo = {
        x: 0,
        y: 0,
        historyX: [],
        historyY: [],
        historyTime: [],
    };
    function findDelta(point) {
        return {
            x: point.x - touchInfo.x,
            y: point.y - touchInfo.y,
        };
    }
    function onStart(point) {
        touchInfo.x = point.x;
        touchInfo.y = point.y;
        touchInfo.historyX = [0];
        touchInfo.historyY = [0];
        touchInfo.historyTime = [Date.now()];
    }
    function onMove(point) {
        const delta = findDelta(point);
        touchInfo.historyX.push(delta.x);
        touchInfo.historyY.push(delta.y);
        touchInfo.historyTime.push(Date.now());
        while (touchInfo.historyTime.length > 10) {
            touchInfo.historyTime.shift();
            touchInfo.historyX.shift();
            touchInfo.historyY.shift();
        }
    }
    function onEnd() {
        const velocity = {
            x: 0,
            y: 0,
        };
        const length = touchInfo.historyTime.length;
        if (length > 2) {
            let i = length - 1;
            const time1 = touchInfo.historyTime[i];
            const x = touchInfo.historyX[i];
            const y = touchInfo.historyY[i];
            while (i > 0) {
                i--;
                const time0 = touchInfo.historyTime[i];
                const time = time1 - time0;
                if (time > 30 && time < 50) {
                    velocity.x = (x - touchInfo.historyX[i]) / time;
                    velocity.y = (y - touchInfo.historyY[i]) / time;
                    break;
                }
            }
        }
        touchInfo.historyTime = [];
        touchInfo.historyX = [];
        touchInfo.historyY = [];
        return velocity;
    }
    return {
        onStart,
        onMove,
        onEnd,
    };
}