html5 图片360旋转

test.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>图片360度旋转</title>
    <style>
        input {
            font-size:18px;
            padding:5px 20px 5px 20px;
            font-weight:bold;
            color:white;
            background-color:#c5464a;
            cursor:pointer;
            border:none;
            outline:none;
            border-radius:7px 7px 7px 7px;
        }

    </style>
    <script  type="text/javascript"  src="test.js"></script>
</head>
<body>
<input type="button" value="←">
<input type="button" value="→">
<div id="mydiv">
    <img src="img3.jpg" id="img">
</div>
</body>
</html>

　　test.js

window.onload = function() {
    var inputval = document.getElementsByTagName('input');
    var imgval = document.getElementById('img');
    var yimg = new Image();
    var iNow = 0;
    yimg.onload = function() {
        draw(imgval);
    }

    yimg.src = imgval.src;

    function draw(obj) {
        var c = document.createElement('canvas');
        var cxt = c.getContext('2d');

        c.width = obj.width;
        c.height = obj.height;

        obj.parentNode.replaceChild(c, obj);

        cxt.drawImage(obj, 0, 0);

        inputval[1].onclick = function() {
            if (iNow == 3) {
                iNow = 0;
            } else {
                iNow++;
            }
            toChange();
        };


        inputval[0].onclick = function() {
            if (iNow == 0) {
                iNow = 3;
            } else {
                iNow--;
            }
            toChange();
        };

        function toChange() {
            switch (iNow) {
                case 0:
                    c.width = obj.width;
                    c.height = obj.height;
                    cxt.rotate(0 * Math.PI / 180);
                    cxt.drawImage(obj, 0, 0);
                    break;
                case 1:
                    c.width = obj.height;
                    c.height = obj.width;
                    cxt.rotate(90 * Math.PI / 180);
                    cxt.drawImage(obj, 0, -obj.height);
                    break;
                case 2:
                    c.width = obj.width;
                    c.height = obj.height;
                    cxt.rotate(180 * Math.PI / 180);
                    cxt.drawImage(obj, -obj.width, -obj.height);
                    break;
                case 3:
                    c.width = obj.height;
                    c.height = obj.width;
                    cxt.rotate(270 * Math.PI / 180);
                    cxt.drawImage(obj, -obj.width, 0);
                    break;
                case 4:
                    c.width = obj.width;
                    c.height = obj.height;
                    cxt.rotate(360 * Math.PI / 180);
                    cxt.drawImage(obj, obj.width, obj.height);
                    break;
            }
        }
    }
}

　　图片：

效果：

2017-09-08 23:03:47