Restart background SVG animation

问题:

I have an SVG set as a background image of an element. The first time the element is displayed, the animation plays correctly.

On subsequent displays (e.g. if a duplicate of the element is injected via JavaScript, or if the background image is removed and added back with CSS/JavaScript), the animation does not start from the beginning. I think this is intended functionality as the image is not considered to have been reloaded by the browser - it uses the in memory version which is already animating.

Here is a demo of this (not mine): http://www.luigifab.info/public/svg-smil/test.html

There are some associated browser bugs reports for Firefox and Chrome, but as above I think this is intended functionality.

Is there any way to get my SVG animation to reset/replay whenever the image is displayed?

I'm ideally looking for a solution using just CSS and SVG - else a solution with JavaScript if this is not possible.

回答1:

I think your guess "... as the image is not considered to have been reloaded by the browser - it uses the in memory version which is already animating" is correct, as the SVG file is cached! So without a (real) 'reload' the animation is not triggered (again).

Well, firstly let's have a look at SVG animations. There are two attributes you can use inside an animation element which are used to repeat the animation - see Repeating Animations and The ‘animate’ element. In your case the animation runs only once (no repetition).

So you would need Javascript to somehow "trigger" the animation.
This is possible in principle (example: Advanced SVG Animation Techniques), but only if the SVG file is part of the DOM, which you can access via Javascript. Therefor you have to include the SVG file as an <object>.

As soon as you use a SVG file in an <img> tag or as a CSS background-image you have no script access to the file.

So the only way I could think of to achieve your goal is to prevent the browser from caching the SVG file (see How (and how not) to Control Caches), or to use the SVG file in an <object> element so that you can control the animation via Javascript.

BTW: luigifab's answer is not that bad. This is an often used "trick" to force reload of a file/ an image - see The Cache Trick

回答2:

As @netsurfer said, I solved this issue by using an object. Here is an example:

<object type="image/svg+xml" data="my.svg"></object>

Every time I dynamically inject the SVG object the animation starts from the beginning.

回答3:

A possibility is to change image URL to force browser reload.

回答4:

Implementation for luigifab's answer. put some random things at the end of the url parameter, this will force browser to think that the resource is a "new resource". Demo

回答5:

This has worked for me, Simply adding and removing "play" class to a div element by adding setTimeout to delay classList.add('play') so the class can be removed and then applied

CSS

@keyframes play60 {
        0% {
            background-position: 0px 0px;
        }
        100% {
            background-position: -38400px 0px;
        }
    }
    .shapeshifter {
        animation-duration: 1000ms;
        animation-timing-function: steps(60);
        animation-fill-mode: forwards;
        width: 640px;
        height: 640px;
        background-repeat: no-repeat;
    }
    .shapeshifter.play {
        animation-name: play60;
    }

JS:

document.getElementById('shape').addEventListener('mouseover', () => {
    document.getElementById('shape').classList.remove('play')
    setTimeout(() => {
        document.getElementById('shape').classList.add('play');
    }, 1)
})

HTML

<div class="shapeshifter " id="shape" style="background-image: url(shape.svg)"></div>

回答6:

Use a random key in the url for cache busting. Though your example does not have a long animation to properly test it, I have added repeatition of loading the image to make the difference noticable.

url + "&" + Math.random()

No reload demo with constant URL: http://jsfiddle.net/4ZBLr/8/

Reload demo with random URL src: http://jsfiddle.net/4ZBLr/9/

回答7:

I think in many scenarios setCurrentTime(0) is the best solution -- if supported by the browser. Here is an example (assuming you use the <object> tag for embedding, of course):

let content = document.getElementById("object-id").contentDocument;
let svg = content.getElementsByTagName("svg")[0];
if(svg.getCurrentTime() > 10)
  svg.setCurrentTime(0);

More infos about the relevant API can be found here: https://developer.mozilla.org/en-US/docs/Web/API/SVGSVGElement