panlippt/assets/js/shake.js

运行在浏览器中的ppt 演示框架

(function (window, document) {

/**
 * from :https://github.com/alexgibson/shake.js/blob/master/shake.js
 *
 */
    /**
     * 摇一摇实现-抽奖游戏
     * @global
     * @class Shake
     *
     * @example
     * ```html
     * <script src="../output/template/common/bdbox/game/shake.js"></script>
     * <script>
     * window.addEventListener('shake', shakeEventDidOccur, false);
     * function shakeEventDidOccur () {
     *     alert('被摇了');
     * }
     * </script>
     * ```
     */
    function Shake() {

        //feature detect
        this.hasDeviceMotion = 'ondevicemotion' in window;

        //default velocity threshold for shake to register
        this.threshold = 15;

        //use date to prevent multiple shakes firing
        this.lastTime = new Date();

        //accelerometer values
        this.lastX = null;
        this.lastY = null;
        this.lastZ = null;

        //create custom event
        if (typeof document.CustomEvent === "function") {
            this.event = new document.CustomEvent('shake', {
                bubbles: true,
                cancelable: true
            });
        } else if (typeof document.createEvent === "function") {
            this.event = document.createEvent('Event');
            this.event.initEvent('shake', true, true);
        } else {
          return false;
        }
    }

    //reset timer values
    Shake.prototype.reset = function () {
        this.lastTime = new Date();
        this.lastX = null;
        this.lastY = null;
        this.lastZ = null;
    };

    //start listening for devicemotion
    Shake.prototype.start = function () {
        this.reset();
        if (this.hasDeviceMotion) { window.addEventListener('devicemotion', this, false); }
    };

    //stop listening for devicemotion
    Shake.prototype.stop = function () {

        if (this.hasDeviceMotion) { window.removeEventListener('devicemotion', this, false); }
        this.reset();
    };

    //calculates if shake did occur
    Shake.prototype.devicemotion = function (e) {

        var current = e.accelerationIncludingGravity,
            currentTime,
            timeDifference,
            deltaX = 0,
            deltaY = 0,
            deltaZ = 0;

        if ((this.lastX === null) && (this.lastY === null) && (this.lastZ === null)) {
            this.lastX = current.x;
            this.lastY = current.y;
            this.lastZ = current.z;
            return;
        }

        deltaX = Math.abs(this.lastX - current.x);
        deltaY = Math.abs(this.lastY - current.y);
        deltaZ = Math.abs(this.lastZ - current.z);

        if (((deltaX > this.threshold) && (deltaY > this.threshold)) || ((deltaX > this.threshold) && (deltaZ > this.threshold)) || ((deltaY > this.threshold) && (deltaZ > this.threshold))) {
            //calculate time in milliseconds since last shake registered
            currentTime = new Date();
            timeDifference = currentTime.getTime() - this.lastTime.getTime();

            if (timeDifference > 1000) {
                window.dispatchEvent(this.event);
                this.lastTime = new Date();
            }
        }

        this.lastX = current.x;
        this.lastY = current.y;
        this.lastZ = current.z;

    };

    //event handler
    Shake.prototype.handleEvent = function (e) {

        if (typeof (this[e.type]) === 'function') {
            return this[e.type](e);
        }
    };

    //create a new instance of shake.js.
    var myShakeEvent = new Shake();
    myShakeEvent.start();

}(window, document));