HTML-in-Canvas

111 dannyobrien 55 8/2/2025, 10:26:47 PM github.com ↗

Comments (55)

ha1zum · 5h ago
This could have a great utility, but for me HTML in canvas in HTML feels so cursed.

To make it make sense in my opinion canvas should already be a first class format for web browsers, so it doesn't have to be inside a HTML.

Then we would have a choice of HTML-first page with canvas elements in it, or a canvas-first page with HTML elements in it.

But what do I know.

bapak · 2h ago
I don't see a problem with what you're saying at all. For reference, you can already have HTML in SVG in HTML in SVG.

If you have a canvas-first page, where do you store the title? Right, in <title>, so

    <!doctype html>
    <title>My canvas site</title>
    <canvas style="fill all">

In reality they should really just allow content in the canvas element and call it a day:

    <canvas type="html">
        <h1>Canvassing</h1>
    </canvas>
ha1zum · 15m ago
> you can already have HTML in SVG in HTML in SVG

It's kind of different because SVG and HTML are both XML-like text-based format, doesn't feel that wrong to mix them together. Unlike with canvas..

chii · 1h ago
but then what's the point of the canvas here? Unless if it was possible to mix and match canvas painting operations seamlessly with the declared elements...
socalgal2 · 5h ago
canvas first sites suck. They can't use any system services as it would all be a privacy issue. They can't use the system dictionary for correction since to do so they'd need the contents of the dictionary or at least a way to query user customized corrections. Similarly they can't offer the system level accessibility but end up having to roll their own in which case, every app that uses canvas has a completely different UI.
nemomarx · 4h ago
That's basically how flash sites worked, and those were pretty common?
desiderantes · 4h ago
They said that those kind of sites sucked. Common or not.
Liron · 5h ago
What if you want an HTML-first page with a canvas in it, but then you realize you want some layout/styling for the text within the canvas? Seems unnecessary to propagate that situation up to the type of top-level page.
thrance · 4h ago
And then what if you realize you need a canvas-in-the-html-in-the-canvas? It's endless. Canvas-first makes sense, it's basically how it works everywhere outside of the web. Start with the smallest abstractions and build on them (html on canvas) rather than leave escape hatches to your big abstractions because they fail to cover every use cases (canvas in html).
sitkack · 4h ago
If you support the DOM and hitscan, then it doesn't matter. You can red pill Ouroboros yourself all day and not care. Every element a canvas, every raindrop an ocean.
jonplackett · 4h ago
I think you invented Flash, though saying that embedding flash in harm as also a pain!

No comments yet

BobbyTables2 · 6h ago
I suppose all we need to do now is to compile a browser into WASM and run that browser inside a canvas element of the main browser…
sangeeth96 · 5h ago
How about an entire OS with IE? https://copy.sh/v86/?profile=windows2000
socalgal2 · 5h ago
tombh · 4h ago
Where does SVG's `foreignObject` fit into this? It seems that SVG supports all of thelproposal already? As is evidenced by projects like https://github.com/zumerlab/snapdom that can take "screenshots" of the webpage by copying the DOM with inlined styles into a `foreignObject` tag in an SVG. Then of course that SVG can be rendered to a canvas.
progers7 · 3h ago
This proposal is a lot like an easier way to draw foreign object into canvas. This proposal supports new features too, such as updating the canvas when the content changes, and interactivity.
mmastrac · 6h ago
rapnie · 20m ago
I searched for it in the text, but it is the missing one to add (and might cross-ref to "TODO: Don't be evil").
ttoinou · 7h ago
Soon we’re gonna need Canvas rendering inside of HTML-in-Canvas
bastawhiz · 6h ago
It should already work if the nested canvas uses the same approach. It's not cyclic, though. To make cyclic canvases work, you need to manually draw the parent canvas to a nested canvas.
reactordev · 4h ago
I support this, as odd as it is. There’s times when you’re needing something drawn but can easily reuse an html element from elsewhere. Previously you’d have to render that to a bitmap offscreen and then copy that to a full screen quad or draw it on the canvas. Up until recently, even if you tried to z-index elements with position absolute it would be visually overwritten by the canvas (I think this is mostly fixed though).

I don’t know if this is the best solution but it’s better than previous hacks. IF you need to go that route. Basically html2canvas.

talkingtab · 5h ago
There is a real problem using canvas to replace HTML.

Not all but most HTML. I have not found a good solution for the issue of doing something like MDX in canvas. I have tried SDF, looked at 2D canvas Text, Troika, MSDF. You can get text, it is just that laying it out is very difficult. React three drei has the ability to put HTML into the threejs ecosystem, but there are issues about CSS and text that make that impractical.

For me the use case is very simple. I would like to take an MDX file and show it in a mesh. Laid out. Maybe I am missing something because I am new to the whole threejs thing, but I really tried.

A good article about text https://css-tricks.com/techniques-for-rendering-text-with-we...

And an example from the above article: https://codesandbox.io/p/sandbox/css-tricks-msdf-text-fks8w

This shows it can be done, I gave up trying to reproduce it in React-three-fiber.

Why? Personally, I think the use of 3D graphics produces an interface for users that is an order or magnitude better for users. The real question (and an interesting one to consider) is why are we still building HTML first websites?

hyperhello · 7h ago
I see reliable rich text editing as more of a priority.
c-smile · 5h ago
From the very beginning in Sciter an Image can be constructed in two ways at runtime ( other than just getting loaded image reference):

1. By painting on it using Canvas/Graphics API:

    new Graphics.Image(width, height, painter(graphics) [,initColor]);  
Where _painter_ is a function used for paining on the image surface using Canvas/Graphics reference.

2. By making snapshot of the existing DOM element:

    new Graphics.Image(width, height, element [,initColor])
Such images can be used in DOM, rendered by other Canvas/Graphics as also in WebGL as textures.

See: https://docs.sciter.com/docs/Graphics/Image#constructor

codelikeawolf · 6h ago
I immediately got "Pimp My Ride" vibes. Yo dawg, I heard you like HTML so I put HTML inside the canvas inside the HTML.
SeanAnderson · 6h ago
I read the title and said "shut the fuck up, don't do that." but then I read the rationale and it's fair. It's true there is no layout engine inside canvas, and that is a pain, but I'm not sure it's such a pain as to invite this recursive hell.
nine_k · 6h ago
One of the more senior engineers I worked with told me: "Every real-life data structure I encountered was tree-like".

It would be easiest to just ask the browser to render a fragment of HTML onto a canvas, or onto some invisible bitmap, like you can with most other UI toolkits.

monster_truck · 6h ago
They would never do this because of fingerprinting, which is already the cause of most of the reasons we cannot 'just' do a lot of things, unfortunately.

E: And the infamous other half: malware. A bit over a decade ago malware devs started using canvas to do things like hide fragments inside of bitmap data in seemingly harmless ads and then a second script would extract and assemble it to evade detection.

rezonant · 46m ago
The web platform can already do this, see SVG foreignObject elsewhere in the thread. The key is to have the proper bounds in place (cross origin resources, etc), and the infrastructure for that is already in place.

This just removes the extra step of relying on SVG to accomplish rendering the HTML, adds a path for getting this content into the accessibility tree, and supporting input on the rendered elements.

mook · 6h ago
Yeah, that's already available in Firefox for chrome/extensions, but not allowed for the web due to fingerprinting and other security risks. For example, rendering an iframe of your bank account…

https://searchfox.org/mozilla-central/rev/f691af5143ebd97034...

bongodongobob · 5h ago
> Every real-life data structure I encountered was tree-like

I don't understand what the takeaway is here. Is that surprising? Is it not? What does "real-life" mean?

nine_k · 47m ago
As found in production code, not (only) in textbooks and academic papers.

This is an exaggeration, of course.

do_not_redeem · 5h ago
> Every real-life data structure I encountered was tree-like

What does this even mean? Is a hash map "tree-like" somehow? Or is a hash map just a toy data structure with no real-life use cases?

UltraSane · 4h ago
Nested hash maps are trees
teaearlgraycold · 6h ago
You could disallow recursion.

No comments yet

cheeaun · 5h ago
Kinda reminds me of Flipboard https://engineering.flipboard.com/2015/02/mobile-web (2015)
jonplackett · 4h ago
Can it just be CSS on canvas - so you can do styling and layout nicely but not weirdness of an html sandwich?
donatj · 5h ago
I feel like this is bound to get kneecapped for the same reason as other canvas features, fingerprinting.
tantalor · 7h ago
Waterluvian · 7h ago
45kb gzipped is pretty beefy but incredibly small when you consider just what it takes to make this work today. If I understand correctly, it’s basically a DOM and CSS renderer.
kizer · 7h ago
There's a bunch of CSS, etc. not supported by that. It would be great to have access to a native API to get bitmaps of the DOM.
masswerk · 6h ago
Well, a fingerprinting dream…

Meaning, no way, just for the security aspect.

nikeee · 5h ago
Is that being made to make Flutter not being like Flash on the web?
ivanjermakov · 5h ago
RIP accessibility
progers7 · 3h ago
Accessibility is a key reason for this proposal. Today, canvas accessibility is quite limited. This proposal enables the browser to know how accessible dom elements map to canvas pixels.
tones411 · 3h ago
Next someone will want to render a canvas in the html in the canvas.
tinalovely101 · 5h ago
It seems to be impossible with html version.
sampton · 5h ago
Servo + wasm.
erichocean · 4h ago
My Blossom library has a layout engine for Canvas [0]

[0] https://github.com/erichocean/blossom

russellbeattie · 4h ago
How about a flag on the body element like:

    <body canvas="true"></body> 
This would make the entire visible page into a canvas-like drawing surface which also renders DOM elements as per usual. At some level there's a process which rasterizes the DOM - opening drawing APIs into that might be a better solution.

It's sort of the same thing as HTML in canvas conceptually, but architecturally it makes DOM rendering and canvas rendering overlapping equals with awareness going both ways. E.g., a line drawn on the page will cause the DOM elements to reflow unless told to ignore it.

pyrolistical · 2h ago
Screen readers all cried in unison
charcircuit · 5h ago
This sounds really useful for being able to use standard web technology with webxr.
socalgal2 · 5h ago
I've never understood why they couldn't have just used the existing 3D CSS for WebXR. All the data is there, all they need to do is render the DOM from 2 POVs, one for each eye. They could even have had some standard to let it auto composite with WebGL.
deadbabe · 5h ago
true horror is finding every element of the HTML page your on has been rendered in a Canvas
turnsout · 5h ago
Sad to say, but the first thing I thought was "oh good, a new fingerprinting target."