For someone rooted in graphic design and illustration, I typically hate running across visuals on the internet. Aside from being numbed by ads, the fact of the matter is that a large percentage of the graphical presentation on the web is just bandwidth-stealing window dressing with little impact on the surrounding content. Part of my plan with this blog was to avoid graphics almost entirely, and yet over the past month or so, I have littered this space with a handful of SVGs. I think, for the most part, they have added meaningful visual aids to the surrounding content, but I still don’t want to make too much of a habit of it.
I’m far more comfortable with SVGs (or, vector graphics in general) because I find it easier to have them settle onto the page naturally without becoming jarring. I could obviously restrict the palette of a raster image to the palette of my site, and render a high resolution PNG with manageable file size, but scaling will still come into play, type may be mismatched… aside from being accessibility issues, these things have subtle effects on visual flow. I’m thankful that SVG has been adopted as well as it has, and that it’s relatively simple to write or manipulate by hand. Following is the process I go through to make my graphics as seamless as possible.
Generally speaking, the first step is going to be to get my graphic into Illustrator. Inside Illustrator, I have a palette corresponding to my site’s colors. Making CSS classes for primary, secondary, tertiary colors is in my to-do list, but I need to ensure nothing will break with a class defining both
fill. Groups and layers (mostly) carry over when Illustrator renders out an SVG, so I make a point of going through the layer tree to organize content. Appearances applied to groups cascade down in the output process, so (as far as SVG output is concerned) there’s no point in, say, applying a fill to a group – each individual item will get that fill in the end anyway. I use Gentium for all of the type, as that is ideally how it will be rendered in the end, though it’s worth quickly checking how it all looks in Times New Roman as well.
Once I get things colored and grouped as I need them, I crop the artboard to the artwork boundaries. This directly affects the SVG viewbox, and unless I need extra whitespace for the sake of visually centering a graphic, I can rely instead on padding or the like for spacing.
Once in the SVG Save dialog, I ensure that ‘Type’ is set to ‘SVG’. I don’t want anything converted to an outline, because I want the type to visually fall back with the rest of my page. I never actually save an SVG file from Illustrator, I just go to ‘SVG Code…’ from the Save dialog, and copypaste it elsewhere for further massaging. This involves:
height="15em"1, or somewhere near that as far as height is concerned. This keeps the images centered and prevents unsightly scaling issues on mobile.
- Removing all references to
font-family, which ensures that my page’s font cascades down. Generally this means that it’ll render in Gentium as when I was designing it, but if the page falls back for whatever reason, the graphic will too.
- Ensuring unique IDs are used. If I didn’t name layers, etc. in Illustrator, I could wind up with several objects on a page with
id="Layer1", which would obviously violate HTML spec.
- Getting rid of any empty groups. Sometimes Illustrator just throws in a bunch of
<g></g>at the end for no discernible reason.
- Grouping similar objects, as best as possible, applying shared attributes to the group instead of individual objects
- Deleting empty
<rect>s, which Illustrator creates around text boxes. Presumably this is because, in Illustrator, text boxes themselves can have appearances applied to them like any other object. It would be nice if it was smart enough to only carry this over if there was some sort of appearance, though.
- Adding a
<title>if a description is necessary, or
aria-hidden="true"to the SVG if the image can be ignored by assistive technology.
- Likewise, if the graphic is being ‘read’, adding
aria-hidden="true"to (likely) all of the text elements within. In my diagrams, assistive tech users certainly don’t need to hear a bunch of random numbers without context, especially when I’ve provided a
Illustrator seemingly outputs SVG with the intent being structural accuracy if the file is read back in for editing, which is often counterproductive for web use, which would prioritize small filesize without a sacrifice in selection ordering or visual accuracy. To be fair, I just installed 2018 and haven’t tested its SVG waters yet, so we’ll see how Adobe managed to
mess that up handle that.
Finally, it’s worth mentioning SVGO (and the web-based SVGOMG). Very customizable optimization, definitely more useful once one starts dealing with more intricate, complicated SVGs. I’m happy to optimize mine down by hand, and stop there – but I’m keeping them to a handful of kilobytes anyway.
- This used to say
height="15rem", but apparently, rem is an invalid unit for declaring the height of an SVG. I am going through and replacing all of these height declarations with ems instead. This is weird to me, and Chrome and IE/Edge both take no issue with use of rems, but Firefox renders them full-bore. ↩︎