Re: Allow auto-resize on iframe

On 9 Feb 2016, at 08:28, Jake Archibald <jakearchibald@google.com> wrote:

> Does this suffer from the same infinite loop issue as element queries?
> 
> A media query in the iframe could react to its new height by changing its height.



Yes, but I think the browser can be a bit more stupid about it :-)



It is possible that the framed content includes a media query that is based on height, and this is a problem, as unlike a normal viewport, this height is now dependent on the content.

But we can cheat here, as we don't need to consider every edge case that the element queries proposal needed to consider.



So if the browser was to do an initial layout, and it determines a second pass is necessary, let it do that.

But if this causes the document to...

1) Alternate between two heights, "then render the iframe viewport at the larger size". This will cause the iframe to be a bit too big, but it won't really cause any problems.

2) Keep shrinking, "then render the iframe viewport at the larger size", and again, allow it to be too big.

3) Keep growing, "then render the iframe viewport at the larger size" (second pass), and now disable the auto-resize, so it basically falls back to the old behaviour of using a scroll bar (and if the browser is feeling charitable, it could add a note in the dev console, explaining why this happened).



That said, In every case I've looked at, this shouldn't be a problem, as the iframe only needed to change the height, whereas most media queries are based on the width.

This is because the width is being enforced by the viewport on to the content (as we hate horizontal scroll bars), where this restriction goes down the nodes... whereas the height is determined by the content, and is passed up the nodes to the viewport (resulting in the vertical scroll bar).

This is why I'm only proposing that the iframe supports re-sizing on the height, where the parent document sets the width.

And it's not like the current JavaScript solutions/hacks don't have the same problem :-)



I must admit though, I'm not that familiar with the low level rendering process of the browsers, so I may have been oversimplifying it a bit (says he who really should get back to finding out how to fix https://crbug.com/469663)

Craig