基于HTML5 Canvas 实现的 Loading 效果

 var loaders = [

    {

        width: 100,
        height: 50,
        padding: 10,

        stepsPerFrame: 2,
        trailLength: 1,
        pointDistance: .03,

        strokeColor: ‘#FF7B24‘,

        step: ‘fader‘,

        multiplier: 2,

        setup: function () {
            this._.lineWidth = 5;
        },

        path: [

            [‘arc‘, 10, 10, 10, -270, -90],
            [‘bezier‘, 10, 0, 40, 20, 20, 0, 30, 20],
            [‘arc‘, 40, 10, 10, 90, -90],
            [‘bezier‘, 40, 0, 10, 20, 30, 0, 20, 20]
        ]
    },

    {

        width: 30,
        height: 30,

        stepsPerFrame: 2,
        trailLength: .3,
        pointDistance: .1,
        padding: 10,

        fillColor: ‘#D4FF00‘,
        strokeColor: ‘#FFF‘,

        setup: function () {
            this._.lineWidth = 20;
        },

        path: [
            [‘line‘, 0, 0, 30, 0],
            [‘line‘, 30, 0, 30, 30],
            [‘line‘, 30, 30, 0, 30],
            [‘line‘, 0, 30, 0, 0]
        ]
    },

    {

        width: 100,
        height: 100,

        stepsPerFrame: 1,
        trailLength: 1,
        pointDistance: .025,

        strokeColor: ‘#05E2FF‘,

        fps: 20,

        setup: function () {
            this._.lineWidth = 2;
        },
        step: function (point, index) {

            var cx = this.padding + 50,
                cy = this.padding + 50,
                _ = this._,
                angle = (Math.PI / 180) * (point.progress * 360);

            this._.globalAlpha = Math.max(.5, this.alpha);

            _.beginPath();
            _.moveTo(point.x, point.y);
            _.lineTo(
                (Math.cos(angle) * 35) + cx,
                (Math.sin(angle) * 35) + cy
            );
            _.closePath();
            _.stroke();

            _.beginPath();
            _.moveTo(
                (Math.cos(-angle) * 32) + cx,
                (Math.sin(-angle) * 32) + cy
            );
            _.lineTo(
                (Math.cos(-angle) * 27) + cx,
                (Math.sin(-angle) * 27) + cy
            );
            _.closePath();
            _.stroke();

        },
        path: [
            [‘arc‘, 50, 50, 40, 0, 360]
        ]
    },

    {

        width: 100,
        height: 50,

        stepsPerFrame: 1,
        trailLength: 1,
        pointDistance: .1,
        fps: 15,
        padding: 10,
        //step: ‘fader‘,

        fillColor: ‘#FF2E82‘,

        setup: function () {
            this._.lineWidth = 20;
        },

        path: [
            [‘line‘, 0, 20, 100, 20],
            [‘line‘, 100, 20, 0, 20]
        ]
    },

    {

        width: 100,
        height: 100,

        stepsPerFrame: 7,
        trailLength: .7,
        pointDistance: .01,
        fps: 30,

        setup: function () {
            this._.lineWidth = 10;
        },

        path: [
            [‘line‘, 20, 70, 50, 20],
            [‘line‘, 50, 20, 80, 70],
            [‘line‘, 80, 70, 20, 70]
        ]
    },

    {

        width: 100,
        height: 100,

        stepsPerFrame: 4,
        trailLength: 1,
        pointDistance: .01,
        fps: 25,

        fillColor: ‘#FF7B24‘,

        setup: function () {
            this._.lineWidth = 10;
        },

        step: function (point, i, f) {

            var progress = point.progress,
                degAngle = 360 * progress,
                angle = Math.PI / 180 * degAngle,
                angleB = Math.PI / 180 * (degAngle - 180),
                size = i * 5;

            this._.fillRect(
                Math.cos(angle) * 25 + (50 - size / 2),
                Math.sin(angle) * 15 + (50 - size / 2),
                size,
                size
            );

            this._.fillStyle = ‘#63D3FF‘;

            this._.fillRect(
                Math.cos(angleB) * 15 + (50 - size / 2),
                Math.sin(angleB) * 25 + (50 - size / 2),
                size,
                size
            );

            if (point.progress == 1) {

                this._.globalAlpha = f < .5 ? 1 - f : f;

                this._.fillStyle = ‘#EEE‘;

                this._.beginPath();
                this._.arc(50, 50, 5, 0, 360, 0);
                this._.closePath();
                this._.fill();

            }


        },

        path: [
            [‘line‘, 40, 10, 60, 90]
        ]
    },

    {

        width: 100,
        height: 100,

        stepsPerFrame: 3,
        trailLength: 1,
        pointDistance: .01,
        fps: 30,
        step: ‘fader‘,

        strokeColor: ‘#D4FF00‘,

        setup: function () {
            this._.lineWidth = 6;
        },

        path: [
            [‘arc‘, 50, 50, 20, 360, 0]
        ]
    },

    {

        width: 100,
        height: 100,

        stepsPerFrame: 1,
        trailLength: 1,
        pointDistance: .02,
        fps: 30,

        fillColor: ‘#05E2FF‘,

        step: function (point, index) {

            this._.beginPath();
            this._.moveTo(point.x, point.y);
            this._.arc(point.x, point.y, index * 7, 0, Math.PI * 2, false);
            this._.closePath();
            this._.fill();

        },

        path: [
            [‘arc‘, 50, 50, 30, 0, 360]
        ]

    },

    {

        width: 100,
        height: 100,

        stepsPerFrame: 1,
        trailLength: 1,
        pointDistance: .05,

        strokeColor: ‘#FF2E82‘,

        fps: 20,

        setup: function () {
            this._.lineWidth = 4;
        },
        step: function (point, index) {

            var cx = this.padding + 50,
                cy = this.padding + 50,
                _ = this._,
                angle = (Math.PI / 180) * (point.progress * 360),
                innerRadius = index === 1 ? 10 : 25;

            _.beginPath();
            _.moveTo(point.x, point.y);
            _.lineTo(
                (Math.cos(angle) * innerRadius) + cx,
                (Math.sin(angle) * innerRadius) + cy
            );
            _.closePath();
            _.stroke();

        },
        path: [
            [‘arc‘, 50, 50, 40, 0, 360]
        ]
    }

];

        var d, a, container = document.getElementById(‘in‘);


        for (var i = -1, l = loaders.length; ++i < l; ) {

            d = document.createElement(‘div‘);
            d.className = ‘l‘;

            a = new Sonic(loaders[i]);

            d.appendChild(a.canvas);
            container.appendChild(d);

            a.canvas.style.marginTop = (150 - a.fullHeight) / 2 + ‘px‘;
            a.canvas.style.marginLeft = (150 - a.fullWidth) / 2 + ‘px‘;

            a.play();

        }