从HTML5画布直接保存图像(Saving images from HTML5 canvas dir

我通过设置在highcharts网站上的演示的jsfiddle去http://jsfiddle.net/highcharts/PDnmQ/ 。当我点击按钮，保存为PNG，它下载评为下载，而不是一个PNG文件的文件。

HTML：

<script src="http://code.highcharts.com/highcharts.js"></script>
<script src="http://code.highcharts.com/modules/exporting.js"></script>
<script src="http://canvg.googlecode.com/svn/trunk/rgbcolor.js"></script> 
<script src="http://canvg.googlecode.com/svn/trunk/canvg.js"></script>

脚本：

(function (H) {
    H.Chart.prototype.createCanvas = function (divId) {
        var svg = this.getSVG(),
            width = parseInt(svg.match(/width="([0-9]+)"/)[1]),
            height = parseInt(svg.match(/height="([0-9]+)"/)[1]),
            canvas = document.createElement('canvas');

        canvas.setAttribute('width', width);
        canvas.setAttribute('height', height);

        if (canvas.getContext && canvas.getContext('2d')) {

            canvg(canvas, svg);

            var image = canvas.toDataURL("image/png")
                .replace("image/png", "image/octet-stream"); 

            // Save locally
            window.location.href = image;
        } else {
            alert ("Your browser doesn't support this feature, please use a modern browser");
        }

    }
}(Highcharts));

$('#container').highcharts({

    xAxis: {
        categories: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 
            'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
    },

    title: {
        text: 'Click the button and Save as PNG =>',
        align: 'right',
        x: -40
    },

    series: [{
        data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4]
    }],

    exporting: {
        buttons: {
            contextButton: {
                menuItems: [{
                    text: 'Print',
                    onclick: function() {
                        this.print();
                    }
                }, {
                    text: 'Save as PNG',
                    onclick: function() {
                        this.createCanvas();
                    },
                    separator: false
                }]
            }
        }
    }

});

您可以指定数据-URI从画布到你，然后可以下载属性设置文件名属性的定位元素。

例如，可以说这种定位的在你的HTML存在：

<a id="saveAs" href="#">Click to download</a>

当你再抢从画布图像更新锚标记是这样的：

var link = document.getElementById('saveAs');

link.href = canvas.toDataURL();   /// set data-uri as href, defaults to PNG
link.download = 'myFilename.png'; /// set filename

现在，您可以点击锚链接，它将使您下载的文件与设置文件名。

您还可以动态地创建屏幕外的锚标记，并通过模拟点击事件调用一个点击。