today i learned: svg files are literally just html code

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litghter, as in smaller, yess. but keep in mind, that vector graphics need to be rendered, wich depending on circumstance and graphic might become inefficient.

i never crunched the numbers, but basically youre outsourcing the generation of a rastergraphic to those who open up your website.

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XML is a super-set of XHTML's spec.

That's a weird way of saying XHTML is an application of XML.

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It's both of those things

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main difference between raster graphics and vector graphics was the quality

It's not. The primitives, the most basic constitutive building blocks, are different, for raster it's the pixel (a mix of colors, e.g. red/green/blue) whereas for vector it's the ... vector (a relative position elements, e.g. line, circle, rectangle or text start with).

This is a fundamental distinction on how you interact with the content. For raster you basically paint over pixels, changing the values of pixels, whereas for vector you change values of elements and add/remove elements. Both can be lossless though (vector always is) as for raster can have no compression or lossless compression. That being said raster does have a grid size (i.e. how many pixels are stored, e.g. 800x600) whereas vector does not, letting you zoom infinitely and see no aliasing on straight lines.

Anyway yes it's fascinating. In fact you can even modify SVG straight from the browser, no image editor or text editor needed, thanks to your browser inspector (easy to change the color of a rectangle for example) or even the console itself then via JavaScript and contentDocument you can change a lot more programmatically (e.g. change the color of all rectangles).

It's a lot of fun to tinker with!

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They can include runnable JavaScript too, which can cause vulnerabilities in certain contexts. One example from work some years back: We had a web app where users could upload files, and certain users could view files uploaded by others. They had the option to download the file or, if it was a file type that the browser could display (like an image or a PDF), the site would display it directly on the page.

To prevent any XSS (scripts from user-provided files), we served all files with the CSP sandbox header, which prevents any scripts from running. However, at the time, that header broke some features of the video player on certain browsers (I think in Safari, at least), so we had to serve some file types without the header. Mistakenly, we also included image files in the exclusion, as everyone through image files couldn't contain scripts. But the MIME type for SVG files is image/svg+xml... It was very embarrassing to have such a simple XSS vuln flagged in a security audit.

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we could modify the desktop environment and make it waaaaay lighter by getting rid of jpg or png icons and just using pure svg on it

That's already happening.

You can also change the main color of many SVGs (icons or even desktop backgrounds) with one simple edit, one command, one click.

In web sites, you can assign CSS classes to SVG graphics and thus e.g. change their color according to a theme.

That's my extent of fiddling with it.

IIRC they also use fonts the same way CSS/HTML does.

BTW, there are situations where an SVG is significantly larger than a corresponding raster image. It depends on the content.

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Postscript is also literally just a text based programming language for drawing stuff. You can create loops and recursions and all kinds of crazy transformations with a few lines of code.

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I'm not sure that lossy compression on vectors is strictly impossible.

You can do things like store less colour information and simplify splines so that curves are less complex.

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One should always optimize assets for the web, this includes svg as well.

For critical paths I use https://optimize.svgomg.net/ a svg file optimizer. Svgs that are coming directly from illustrator or sketch are getting better these days but this little tool is invaluable regardless.

I think you can run this local too

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Schrödinger's SVGs?

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Yeah, it depends on if you view source

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No, SVG files are not HTML.

Please change this post title (currently "today i learned: svg files are literally just html code"), to avoid spreading this incorrect factoid!

I suggest you change it to "today i learned: svg files contain code in an html-like language" or something like that.

SVG is a dialect of XML.

XML and HTML have many similarities, because they are both are descendants of SGML. But, as others have noted in this thread, HTML is also not XML. (Except for when it's XHTML...)

Like HTML, SVG also can use CSS, and, in some environments (eg, in browsers, but not in Inkscape) also JavaScript. But, the styles you can specify with CSS in SVG are quite different than those you can specify with CSS in HTML.

Lastly, you can embed SVG in HTML and it will work in (modern) browsers. You cannot embed HTML in SVG, however.

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I made an interactive map: drew in Inkscape, gave the interactive elements numbers for ids, then substituted the id='xxx' in vim with the php code and js function calls, picking up the number from the id tag and inserting it appropriately in php code and function arguments. 250 interactive elements taken care of in a single vim substitute. My bestest development power move yet

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for example, on a linux distro, we could modify the desktop environment and make it waaaaay lighter by getting rid of jpg or png icons and just using pure svg on it.

this has largely happened; if you're on a dpkg-based distro try running this command:

dpkg -S svg | grep svg$ | sort

...and you'll see that your distro includes thousands of SVG files

::: spoiler explanation of that pipeline:

dpkg -S svg - this searches for files installed by the package manager which contain "svg" in their path
grep svg$ - this filters the output to only show paths which end with svg; that is, the actual svg files. the argument to grep is a regular expression, where $ means "end of line". you can invert the match (to see the paths dpkg -S svg found which only contain "svg" in the middle of the path) by writing grep -v svg$ instead.
the sort command does what it says on the tin, and makes the output easier to read

you can run man dpkg, man grep, and man sort to read more about each of these commands.
:::

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What was the map used for?

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Ommigod, these kids

SVG comes XML (a more coherent/simple version of the SGML that is behind HTML), and specifically from a time where people took XML and made it hyper-complicated with a flurry of extensions and specifications (look up "xml namespaces" "xslt" "xml schema").

The most apparent difference between SGML and XML is than in the former you write tags like without a corresponding , and in the latter you have to close them like (which is shorthand for ).

So... today you learned that what you learned earlier today was close to truth, but not true

PS: A lot of document formats are undercover/zipped XML (eg. the libre office documents, IIRC microsoft's .xlsx and .docx). This is not dissimilar to how json/yaml are widely used today.

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for alpine linux users:

apk info -L $(apk info) | grep -v contains | grep 'svg'

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Oooh, neat! [Cunningham's Law] (https://en.m.wikipedia.org/wiki/Ward_Cunningham#Cunningham's_Law) in action!

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No, it's XML. It's an ancestor of HTML and, unlike HTML, it can be losslessly converted.

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True, in fact I've done so myself (simplifying a curve resulting of hand sketching). Still I'd argue that's not the normal expected behavior of storing the vector file but rather explicitly modifying it.

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today i learned: svg files are literally just html code