CSS colors parsed for canvas use should explicitly state the element to resolve currentcolor against

[heycam]

What is the issue with the HTML Standard?

Various sections that define how 2D canvas context APIs parse CSS color values link to the "parse a CSS <color> value" algorithm in the CSS Color spec. That algorithm expects to be passed in the specific element to resolve currentcolor against, and if no element is passed in, currentcolor resolves to the initial value of 'color'.

The uses of "parse a CSS '' value" (e.g. in the fillStyle setter) do not pass in an element, but there are WPTs that assume it resolves against the <canvas> element (e.g. html/canvas/element/fill-and-stroke-styles/2d.fillStyle.parse.current.basic).

[annevk]

Ah, I messed this up in #10175. I will take this.

[annevk]

The current text reads:

Let parsedValue be the result of parsing the given value with this's canvas attribute's value.

The canvas attribute returns the element.

We shouldn't pass anything though when that is not a canvas element as is the case for OffscreenCanvas. That's a bug.

For reference: https://drafts.csswg.org/css-color-4/#parse-a-css-color-value