使用 .toDataUrl() 将 Chart.js 画布图表转换为图像会导致空白图像 [英] Converting Chart.js canvas chart to image using .toDataUrl() results in blank image

问题描述

我正在使用 Chart.js.我试图通过获取 base 64 字符串将图表转换为图像.本教程 (http://www.chartjs.org/docs/) 在主题:

I am using Chart.js. I am trying to convert the chart to an image by getting a base 64 string. The tutorial (http://www.chartjs.org/docs/) devotes an entire 1 line on the topic:

canvas 元素还允许将内容保存为 base 64字符串，允许将图表保存为图像.

The canvas element also allows for saving the contents as a base 64 string, allowing saving the chart as an image.

canvas 元素具有toDataURL 方法，该方法返回图像的base64 字符串.但是，当我这样做时，它呈现的图像只是一个具有图表尺寸的透明矩形，它不包括图表内容.

A canvas element has the method of toDataURL, which returns a base64 string of the image. However, when I do that, the image it renders is just a transparent rectangle with the dimensions of the chart, and it does not include the chart contents.

这是一个小提琴:http://jsfiddle.net/KSgV7/

小提琴中的图像"带有黑色边框，因此您可以看到它们应该在哪里，因为它们似乎只是一个大的透明块.

The "images" in the fiddle are styled with a black border, so you can see where they are supposed to be, since they seem to just be a big transparent block.

有没有人成功地将 Chart.js 图表转换为图像?

Has anyone successfully converted a Chart.js chart to an image?

推荐答案

图表似乎是异步的，因此您可能需要在动画完成时提供回调，否则画布将为空.

The chart seem to be async so you will probably need to provide a callback when the animation has finished or else the canvas will be empty.

var options = {
    bezierCurve : false,
    onAnimationComplete: done  /// calls function done() {} at end
};

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