Drawing a SVG file on a HTML5 canvas at a specific time

问题

I found the topic Drawing an SVG file on a HTML5 canvas about rendering SVG. Is there a way to draw SVG animated file at specific moment of time? I mean, how to change the code

var img = new Image();
img.onload = function() {
    ctx.drawImage(img, 0, 0); // define time at here: time="1.3sec"
}
img.src = "myfile.svg";

such that img contains svg at specific time? The file myfile.svg contains the following:

<svg
   xmlns="http://www.w3.org/2000/svg"
   viewBox="0 0 200 200"
   id="svg2">

    <g transform="translate(100, 100)">
        <path transform="matrix(0.99982594,0.01865711,-0.01865711,0.99982594,0,0)" style="opacity:1;fill:#28b327;fill-opacity:1;stroke:#000000;stroke-width:1.5;stroke-miterlimit:4;stroke-dasharray:none;stroke-dashoffset:0;stroke-opacity:1" d="M 23.755845,-0.77020556 A 23.938168,23.938168 0 0 1 -0.1823229,23.167962 23.938168,23.938168 0 0 1 -24.12049,-0.77020556 23.938168,23.938168 0 0 1 -0.1823229,-24.708373 23.938168,23.938168 0 0 1 23.755845,-0.77020556 Z" id="ball-2-path4136">
        <animate to="M 17.577751,-4.4423325 A 17.748762,27.248762 1.0690357 0 1 -0.67630452,22.470547 17.748762,27.248762 1.0690357 0 1 -17.913594,-5.1046137 17.748762,27.248762 1.0690357 0 1 0.3404618,-32.017493 17.748762,27.248762 1.0690357 0 1 17.577751,-4.4423325 Z" dur="0.2" begin="1.4" attributeName="d" fill="freeze"/></path>

    </g>
</svg>

People usually suggest to use canvg, but as far as I understood it does not support path animation, so my example does not work with it.

回答1:

You can simply use setTimeout to defer the insertion of the square, in this fashion :

var delayInMilliseconds = 3000;

img.onload = function() {
    setTimeout(function() {
        // This will happend 3 seconds after page load
        ctx.drawImage(img, 0, 0);
    }, delayInMilliseconds);
}
img.src = "http://upload.wikimedia.org/wikipedia/commons/d/d2/Svg_example_square.svg";

In case you want to be able to specify a date and time for the event, use a custom function to count the time left to the target date :

function getTimeTo(date) {
    var time = date.getTime() - Date.now();
    return time;
}

And replace delayInMilliseconds with getTimeTo(targetDate). See this fiddle for experimenting.

来源：https://stackoverflow.com/questions/31494737/drawing-a-svg-file-on-a-html5-canvas-at-a-specific-time

标签

javascript

animation

canvas

svg

canvg