如何将元素的重复线性渐变转换为 base64 图像或任何其他格式？

Question

I can't seem to find a way to convert the repeat-linear-gradient to a base64 image format.

background-image: repeating-linear-gradient(-45deg, transparent, transparent 5px, white 5px, white 10px);

My problem is I want to print an HTML page with html2canvas and jsPDF but since html2canvas doesn't support support repeat-linear-gradient , I would like to know if there is a way to convert the value to base64.

Also, since the background image is rendered by the gantt-chart library, I can't change how it is set

Answer 1

Since it's a repeating gradient, you can identify the smallest portion that you can export as image and that will allow you to have the same background by repeating this image.

You are dealing with +-45deg and the last color stop is 10px so the smallest portion is 10px*sqrt(2) = 14.14px for the height and width:

 .box { height: 14.14px; width: 14.14px; background: repeating-linear-gradient(-45deg, transparent, transparent 5px, blue 5px, blue 10px); }

 <div class="box"></div>

You save this as an image and you use any online tool that convert a png to base64:

 .box { height: 100px; margin: 5px; background: url('data:image/png;base64,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'); }

 <div class="box"></div> <div class="box" style="background:repeating-linear-gradient(-45deg, transparent, transparent 5px, blue 5px, blue 10px)"></div>

---

For a dynamic solution I will consider the code used in this previous answer

 var box = document.querySelector(".box"); domtoimage.toPng(box).then(function(dataUrl) { console.log(dataUrl) var image = new Image(); image.onload = function() { document.body.appendChild(image); }; image.src = dataUrl; })

 .box { height: 100px; margin:5px; background: repeating-linear-gradient(-45deg, transparent, transparent 5px, blue 5px, blue 10px); }

 <script type="text/javascript" src="https://css-challenges.com/wp-content/themes/ronneby_child/js/dom-to-image.js"></script> <div class="box"></div>

Also like this:

 var box = document.querySelector(".box"); domtoimage.toPng(box).then(function(dataUrl) { console.log(dataUrl); document.querySelector(".alt").style.background='url('+dataUrl+')'; })

 .box { height: 14.14px; width: 14.14px; background: repeating-linear-gradient(-45deg, transparent, transparent 5px, blue 5px, blue 10px); }.alt { height:100px; margin:5px; }

 <script type="text/javascript" src="https://css-challenges.com/wp-content/themes/ronneby_child/js/dom-to-image.js"></script> <div class="box"></div> <div class="alt"></div>