roundRect requiring an array

[jagenjo]

I can see that the new roundRect requires an array to specify the radius, even when the radius is constant among all corners.

Knowing that most of us are fighting the garbage collector constantly, I do not see it smart to force to pass an array with every call of roundRect.

More when other functions in canvas take advantage of the variable number of arguments, like drawImage.

I suggest to allow the radius parameter to be a number.

[Kaiido]

That was already brought in whatwg/html#5619 (comment) which didn't receive much returns, in either ways.
I wonder if this point shouldn't be brought again on the PR directly now.

FWIW, I personally don't have a strong opinion on this, with a small preference for a single Array, as I feel it is cleaner to have a single signature, and that very long signatures were actually not a great design decision (over the years I often wondered if having a dictionary for drawImage wouldn't have made it more friendly). If you are that much fighting against GC, I guess you could simply store that Array somewhere and reuse it every frame, like you probably already do with a lot of other objects.
But once again, these are not strong oppositions from my side.

[fserb]

I'm fine with it too.

@mysteryDate wdyt?

[mysteryDate]

I've actually had this on my todo list for a while. I totally agree with a single number for ergonomic reasons, didn't think abuot the garbage collector.

[Kaiido]

@mysteryDate I just did update my polyfill to include this single radius option, however doing so I noticed that the current Chrome's implementation has some weird behavior with some stoopid inputs.

I'm not an IDL expert myself, but I believe that the JS value undefined should be converted to NaN by "unrestricted double" (I tested it with globalAlpha and indeed it is there, at least observably: the value did not change).
However, in roundRect undefined will be (observably) treated as 0: the rectangle will be drawn.
This is true for both roundRect(x, y, w, h, undefined) and roundRect(x, y, w, h, [undefined]).

Also the behavior of an Array as the first member of a list in radii seems similarly broken:
passing roundRect(x, y, w, h, [[20]]) treats radii as 0 (a rectangle with no rounded border is drawn), while if I'm not mistaken, [20] to unrestricted double should be 20.

Here is a fiddle with these observations you can check: https://jsfiddle.net/oxvqm597/
And here the same fiddle ran through my polyfill: https://jsfiddle.net/oxvqm597/1/

Could you please confirm that my reading is correct?

[mysteryDate]

whatwg/html#7592
whatwg/html#7621

[fserb]

Closing this as we merged it! Thanks a lot for the feedback. :)