将Google量规表另存为png [英] save google gauge chart as a png

问题描述

我使用的是Google图表，并有一个混合图表页面，一些饼图，一个柱形图和一个量规图

页面具有生成pdf的选项，因此我将图表转换为PNG以在pdf中使用..

所有图表都是以相同的方式生成的，使用div来显示Google图表，使用隐藏的div来存储png图像

  var chart = new google.visualization.Gauge(document.getElementById('gauge'));var hidden =新的google.visualization.Gauge(document.getElementById('gauge_hidden'));//等待图表完成绘制，然后再调用getImageURI()方法.google.visualization.events.addListener(图表，就绪"，函数(){gauge_hidden.innerHTML ='< img src ='+ chart.getImageURI()+'">';});chart.draw(数据，选项); 

此代码在饼图和柱形图上都可以正常工作，但在我看到的量表上

chart.getImageURI不是函数

关于如何获得png的任何想法?

欢呼声

解决方案

我也遇到了同样的问题，但是经过一番阅读后，我得出了这个解决方案:

我正在使用jQuery来简化此操作.

首先，使用XMLSerializer将SVG图表转换为字符串，然后使用btoa将其转换为base64.您可以通过以下方式使用此字符串:

  var s = new XMLSerializer().serializeToString($(chart_div).find('svg')[0]);var base64String ="data:image/svg + xml; base64，" + window.btoa(s); 

就我而言，我需要将压力表绘制为PDF，而DOMPDF不支持此格式，因此，如果需要"data:image/png; base64"字符串，则可以继续使用此解决方案./p>

您需要将"svg + xml; base64"设置为新图像的src，然后将该图像绘制到画布上.之后，您可以使用画布上的toDataURL方法将内容获取为base64 png.

  var s = new XMLSerializer().serializeToString($(chart_div).find('svg')[0]);var image = new Image();image.width = 640;image.height = 480;image.src ='data:image/svg + xml; base64，'+ window.btoa(s);var myCanvas = document.createElement('canvas');myCanvas.width = 640;myCanvas.height = 480;var myCanvasContext = myCanvas.getContext('2d');myCanvasContext.drawImage(image，0,0);//将Google Chart Gague转换为base64，是的！var base64String = myCanvas.toDataURL();  

感谢此答案和此

this code works fin on he pie and column charts, but on the gauge chart I am seeing

chart.getImageURI is not a function

any ideas how I can get the png?

CHeers

解决方案

I was facing this same issue, but after some reading i've come to this solution:

I'm using jQuery to make this a little easier.

First, use XMLSerializer to convert the SVG chart to a string and then use btoa to convert that to base64. You can use this string this way:

var s = new XMLSerializer().serializeToString($(chart_div).find('svg')[0]);
var base64String = "data:image/svg+xml;base64," + window.btoa(s);

In my case i needed to draw the gauge chart to a PDF and DOMPDF doesn't support this format, so if you need a "data:image/png;base64," string, you can continue with this solution.

You need to set the "svg+xml;base64" as src of a new Image and then draw that image to a Canvas. After that you can use toDataURL method from canvas to get the content as base64 png.

var s = new XMLSerializer().serializeToString($(chart_div).find('svg')[0]);
var image = new Image();
image.width = 640;
image.height = 480;
image.src = 'data:image/svg+xml;base64,' + window.btoa(s);
var myCanvas = document.createElement('canvas');
myCanvas.width = 640;
myCanvas.height = 480;
var myCanvasContext = myCanvas.getContext('2d');
myCanvasContext.drawImage(image,0,0);
// get google chart gague to base64, yey!
var base64String = myCanvas.toDataURL();

Thanks to the author of this answer and this post

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