Question

I have an SVG I am building with Javascript. I load in a large SVG file, break it apart into pieces all drawn with paths, and place each element in my page. I’m only using these SVGs as masks for other images I am loading. Basically my structure is like the following.

<svg xmlns="http://www.w3.org/2000/svg" version="1.1" viewBox="26.750152587890625 10.117172241210938 197.24969482421875 348.1596221923828" width="197.25" height="348.16015625">
    <mask id="designMask" maskContentUnits="objectBoundingBox">
        <g id="CutContour1bg">
            <path d="[my path coords]" style="fill:#FFFFFF;">
        </g>
    </mask>
    <image href="http://myImage.jpg" style="mask: url(#designMask);" width="800px" height="800px" x="26.75" y="10.1171875">
</svg>

This renders the image being masked by my SVG perfect, in FF, IE9, Chrome, Safari 5.1 (desktop). In mobile safari however, the image does not render properly. I trace out coords of the mask, they are all correct. In FF I can see the SVG load (all black) then disappear as it becomes the mask. (I am waiting until the design is loaded, then wrap my <g> with <mask> since FF has an issue looking for the mask before the content is loaded.

This tells me the mask’s position is exactly where it needs to be, but the maskContentUnits are not. They remain in the top left corner instead of the object’s bounding box, like I’m telling it. I can barely see part of the image in the mask, so the mask units are correct, but I cannot get the maskContentUnits to work or be read in mobile safari.

Has anyone ever seen this issue, or any idea how to correct it? I hate having this work everywhere except mobile safari, as it is meant to mostly work on mobile… which defeats its not purpose haha.

Thanks!

Answer 1

I haven’t found a way to make maskContentUnits work properly in mobile safari yet, I’m pretty sure it’s just not recognized yet like other browsers. But I figured out a ‘hack’ to make the example work.

The issue is, the mask area resides in the top left corner of the browser, rather than of the svg object being used as the mask. So if you have an svg in the middle of your page, the image being masked will not follow the same positioning.

The way I found for it to work, is, I wrapped the svg inside a div with the same width as the svg, and modify the position of the div instead of the svg. This way the mask is technically still in the ‘top left’ corner, but of the div rather than the offset position of the svg.

If anyone finds a better way, to make maskContentUnits render proper in mobile safari, I’d like to hear it!