Bugzilla

(In reply to Hiroyuki Ikezoe (:hiro) from comment #8)
> Though I don't yet understand fully what the underlying problem causing this bug is, we've already done such kind of expanding the scrollable rect by this [GetExpandedScrollableRect](https://searchfox.org/mozilla-central/rev/7fe1954b761abeff36122b4a6ac74619704ee787/gfx/layers/FrameMetrics.h#182)?

Good point!

I initially envisioned expanding the scrollable rect in a layout sense (such that e.g. `documentElement.scrollHeight` will report the expanded height), but that's probably unnecessarily complicated; it's probably sufficient to just expand the scrollable rect used by APZ, and like you say we already have `GetExpandedScrollableRect` which ensures the scrollable rect covers the composition bounds.

The [place where we compute the minimum zoom](https://searchfox.org/mozilla-central/rev/7fe1954b761abeff36122b4a6ac74619704ee787/gfx/layers/apz/src/AsyncPanZoomController.cpp#5907-5909) for zoom-to-focused-input does not use `GetExpandedScrollableRect` -- maybe fixing this is as simple as using it there?

(In reply to Hiroyuki Ikezoe (:hiro) from comment #8)
> Though I don't yet understand fully what the underlying problem causing this bug is, we've already done such kind of expanding the scrollable rect by this [GetExpandedScrollableRect](https://searchfox.org/mozilla-central/rev/7fe1954b761abeff36122b4a6ac74619704ee787/gfx/layers/FrameMetrics.h#182)?

Good point!

I initially envisioned expanding the scrollable rect in a layout sense (such that e.g. `documentElement.scrollHeight` will report the expanded height), but that's probably unnecessarily complicated; it's probably sufficient to just expand the scrollable rect used by APZ, and like you say we already have `GetExpandedScrollableRect` which returns a rect that covers the composition bounds.

The [place where we compute the minimum zoom](https://searchfox.org/mozilla-central/rev/7fe1954b761abeff36122b4a6ac74619704ee787/gfx/layers/apz/src/AsyncPanZoomController.cpp#5907-5909) for zoom-to-focused-input does not use `GetExpandedScrollableRect` -- maybe fixing this is as simple as using it there?

(In reply to Hiroyuki Ikezoe (:hiro) from comment #8)
> Though I don't yet understand fully what the underlying problem causing this bug is, we've already done such kind of expanding the scrollable rect by this [GetExpandedScrollableRect](https://searchfox.org/mozilla-central/rev/7fe1954b761abeff36122b4a6ac74619704ee787/gfx/layers/FrameMetrics.h#182)?

Good point!

I initially envisioned expanding the scrollable rect in a layout sense (such that e.g. `documentElement.scrollHeight` will report the expanded height), but that's probably unnecessarily complicated; it's probably sufficient to just expand the scrollable rect used by APZ, and like you say we already have `GetExpandedScrollableRect` which returns a rect that covers the composition bounds.

The [place where we compute the minimum zoom](https://searchfox.org/mozilla-central/rev/7fe1954b761abeff36122b4a6ac74619704ee787/gfx/layers/apz/src/AsyncPanZoomController.cpp#5907-5909) for zoom-to-focused-input does not use `GetExpandedScrollableRect` -- maybe fixing this is as simple as using it there in place of `GetScrollableRect`?