slideshow.js

var SlideShow = function(objs, option) {
    /*
        objs, the element to do the slide
    */

    var index = 0;
    var page_size = option.page_size;
    var interval = option.interval || 1000;
    var fade_time = option.fade_time || 300;
    var timeout = option.timeout || 30000;

    var worker = undefined;
    var onChange = option.onChange || function() {};
    var item_num = objs.length;

    var do_slide_page = (item_num >= page_size);

    function animate(offset) {
        offset %= (page_size * item_num);
        if (index < 0) {
            index = page_size * item_num - index;
        }
        index += offset;

        var start_index = parseInt(index / page_size) * page_size;
        var end_index = start_index + page_size;
        var item_page = parseInt(index / item_num);

        // console.log('current index:' + index + ':' + start_index + ':' + end_index);

        // may need to handle fade-in twice issues

        objs.each(function(i, elem) {
            start_index %= item_num;
            end_index %= item_num;
            if (start_index < end_index && (start_index <= i && i < end_index))
            {
                $(elem).fadeIn(fade_time);
            } else if (end_index < start_index && (start_index <= i || i < end_index)) {
                $(elem).fadeIn(fade_time);
            } else {
                $(elem).hide();
            }
        });
        onChange(index);
    }

    // public
    return {
        prevPage: function() {
            animate(-page_size);
        },
        nextPage: function() {
            animate(page_size);
        },
        nextStep: function() {
            animate(1);
        },
        start: function() {
            if (typeof worker === "undefined") {
                this.nextStep();
                worker = setInterval(this.nextStep, interval);
            }
            setTimeout(this.stop, timeout);
        },
        stop: function() {
            if (typeof worker !== "undefined") {
                clearInterval(worker);
                worker = undefined;
            }
        },
        resume: function() {
            if (typeof worker === "undefined") {
                this.nextStep();
                worker = setInterval(this.nextStep, interval);
            }
        },
        onoff: function() {
            if (typeof worker === "undefined") {
                this.resume();
            } else {
                this.stop();
            }
        },
        curIndex: function() {
            return index % item_num;
        }
    }
};

module.exports = SlideShow;