Interesting take on representing charts in an accessible way. I feel like, as web developers, we were fed a myth that lots of markup and attributes automatically makes your content accessible. But it takes more thinking than that.
I've taken a similar approach to layering canvases with normal HTML (typically the HTML is on top). I don't have a problem logically representing what's painted on the canvas and doing my own hit detection either. Shaders and text shaping in canvas sound a lot more attractive to me than placeElement, but I guess we'll see. I should get around to campaigning for ctx.shapeText and ctx.fillGlyphs but I don't know how much folks care about it.
I've taken a similar approach to layering canvases with normal HTML (typically the HTML is on top). I don't have a problem logically representing what's painted on the canvas and doing my own hit detection either. Shaders and text shaping in canvas sound a lot more attractive to me than placeElement, but I guess we'll see. I should get around to campaigning for ctx.shapeText and ctx.fillGlyphs but I don't know how much folks care about it.