var easingFuncs = {
    linear: function (k) {
        return k;
    },
    quadraticIn: function (k) {
        return k * k;
    },
    quadraticOut: function (k) {
        return k * (2 - k);
    },
    quadraticInOut: function (k) {
        if ((k *= 2) < 1) { return 0.5 * k * k; }
        return -0.5 * (--k * (k - 2) - 1);
    },
    cubicIn: function (k) {
        return k * k * k;
    },
    cubicOut: function (k) {
        return --k * k * k + 1;
    },
    cubicInOut: function (k) {
        if ((k *= 2) < 1) { return 0.5 * k * k * k; }
        return 0.5 * ((k -= 2) * k * k + 2);
    },
    quarticIn: function (k) {
        return k * k * k * k;
    },
    quarticOut: function (k) {
        return 1 - (--k * k * k * k);
    },
    quarticInOut: function (k) {
        if ((k *= 2) < 1) { return 0.5 * k * k * k * k; }
        return -0.5 * ((k -= 2) * k * k * k - 2);
    },
    quinticIn: function (k) {
        return k * k * k * k * k;
    },
    quinticOut: function (k) {
        return --k * k * k * k * k + 1;
    },
    quinticInOut: function (k) {
        if ((k *= 2) < 1) { return 0.5 * k * k * k * k * k; }
        return 0.5 * ((k -= 2) * k * k * k * k + 2);
    },
    sinusoidalIn: function (k) {
        return 1 - Math.cos(k * Math.PI / 2);
    },
    sinusoidalOut: function (k) {
        return Math.sin(k * Math.PI / 2);
    },
    sinusoidalInOut: function (k) {
        return 0.5 * (1 - Math.cos(Math.PI * k));
    },
    exponentialIn: function (k) {
        return k === 0 ? 0 : Math.pow(1024, k - 1);
    },
    exponentialOut: function (k) {
        return k === 1 ? 1 : 1 - Math.pow(2, -10 * k);
    },
    exponentialInOut: function (k) {
        if (k === 0) {
            return 0;
        }
        if (k === 1) {
            return 1;
        }
        if ((k *= 2) < 1) {
            return 0.5 * Math.pow(1024, k - 1);
        }
        return 0.5 * (-Math.pow(2, -10 * (k - 1)) + 2);
    },
    circularIn: function (k) {
        return 1 - Math.sqrt(1 - k * k);
    },
    circularOut: function (k) {
        return Math.sqrt(1 - (--k * k));
    },
    circularInOut: function (k) {
        if ((k *= 2) < 1) { return -0.5 * (Math.sqrt(1 - k * k) - 1); }
        return 0.5 * (Math.sqrt(1 - (k -= 2) * k) + 1);
    },
    elasticIn: function (k) {
        var s;
        var a = 0.1;
        var p = 0.4;
        if (k === 0) { return 0; }
        if (k === 1) { return 1; }
        if (!a || a < 1) { a = 1; s = p / 4; }
        else { s = p * Math.asin(1 / a) / (2 * Math.PI); }
        return -(a * Math.pow(2, 10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p));
    },
    elasticOut: function (k) {
        var s;
        var a = 0.1;
        var p = 0.4;
        if (k === 0) { return 0; }
        if (k === 1) { return 1; }
        if (!a || a < 1) { a = 1; s = p / 4; }
        else { s = p * Math.asin(1 / a) / (2 * Math.PI); }
        return (a * Math.pow(2, -10 * k) * Math.sin((k - s) * (2 * Math.PI) / p) + 1);
    },
    elasticInOut: function (k) {
        var s;
        var a = 0.1;
        var p = 0.4;
        if (k === 0) { return 0; }
        if (k === 1) { return 1; }
        if (!a || a < 1) { a = 1; s = p / 4; }
        else { s = p * Math.asin(1 / a) / (2 * Math.PI); }
        if ((k *= 2) < 1) {
            return -0.5 * (a * Math.pow(2, 10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p));
        }
        return a * Math.pow(2, -10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p) * 0.5 + 1;

    },

    // 在某一动画开始沿指示的路径进行动画处理前稍稍收回该动画的移动
    backIn: function (k) {
        var s = 1.70158;
        return k * k * ((s + 1) * k - s);
    },
    backOut: function (k) {
        var s = 1.70158;
        return --k * k * ((s + 1) * k + s) + 1;
    },
    backInOut: function (k) {
        var s = 1.70158 * 1.525;
        if ((k *= 2) < 1) { return 0.5 * (k * k * ((s + 1) * k - s)); }
        return 0.5 * ((k -= 2) * k * ((s + 1) * k + s) + 2);
    },

    // 创建弹跳效果
    bounceIn: function (k) {
        return 1 - easingFuncs.bounceOut(1 - k);
    },
    bounceOut: function (k) {
        if (k < (1 / 2.75)) { return 7.5625 * k * k; }
        else if (k < (2 / 2.75)) { return 7.5625 * (k -= (1.5 / 2.75)) * k + 0.75; }
        else if (k < (2.5 / 2.75)) { return 7.5625 * (k -= (2.25 / 2.75)) * k + 0.9375; }
        else { return 7.5625 * (k -= (2.625 / 2.75)) * k + 0.984375; }
    },
    bounceInOut: function (k) {
        if (k < 0.5) { return easingFuncs.bounceIn(k * 2) * 0.5; }
        return easingFuncs.bounceOut(k * 2 - 1) * 0.5 + 0.5;
    }
};

var N_POINT = 30;

var grids = [];
var xAxes = [];
var yAxes = [];
var series = [];
var titles = [];
var count = 0;
echarts.util.each(easingFuncs, function (easingFunc, name) {
    var data = [];
    for (var i = 0; i <= N_POINT; i++) {
        var x = i / N_POINT;
        var y = easingFunc(x);
        data.push([x, y]);
    }
    grids.push({
        show: true,
        borderWidth: 0,
        backgroundColor: '#fff',
        shadowColor: 'rgba(0, 0, 0, 0.3)',
        shadowBlur: 2
    });
    xAxes.push({
        type: 'value',
        show: false,
        min: 0,
        max: 1,
        gridIndex: count
    });
    yAxes.push({
        type: 'value',
        show: false,
        min: -0.4,
        max: 1.4,
        gridIndex: count
    });
    series.push({
        name: name,
        type: 'line',
        xAxisIndex: count,
        yAxisIndex: count,
        data: data,
        showSymbol: false,
        animationEasing: name,
        animationDuration: 1000
    });
    titles.push({
        textAlign: 'center',
        text: name,
        textStyle: {
            fontSize: 12,
            fontWeight: 'normal'
        }
    });
    count++;
});

var rowNumber = Math.ceil(Math.sqrt(count));
echarts.util.each(grids, function (grid, idx) {
    grid.left = ((idx % rowNumber) / rowNumber * 100 + 0.5) + '%';
    grid.top = (Math.floor(idx / rowNumber) / rowNumber * 100 + 0.5) + '%';
    grid.width = (1 / rowNumber * 100 - 1) + '%';
    grid.height = (1 / rowNumber * 100 - 1) + '%';

    titles[idx].left = parseFloat(grid.left) + parseFloat(grid.width) / 2 + '%';
    titles[idx].top = parseFloat(grid.top) + '%';
});

option = {
    title: titles.concat([{
        text: 'Different Easing Functions',
        top: 'bottom',
        left: 'center'
    }]),
    grid: grids,
    xAxis: xAxes,
    yAxis: yAxes,
    series: series
};