[Gecko Bug 1552089] Don't tweak snapport position even in the case of RTL scroll containers. #16909
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In RTL scroll containers, the right most x-axis scroll position is 0 and
leftward scroll positions are negative values. And also
nsLayoutUtils::TransformFrameRectToAncestor, which is used to tell whether the
snap target element is inside the destination snapport or not [1], returns
negative x-axis positions for elements in RTL scroll containers if the element
is positioned at places where the elements are outside of the initial scroll
position (0, 0). So we don't need to tweak snapport postion even in the case
of RTL scroll containers.
Instead, what we needed in the first place is that we choose a proper x-axis
scroll position that the targe element appears inside the snapport.
[1] https://searchfox.org/mozilla-central/rev/11cfa0462a6b5d8c5e2111b8cfddcf78098f0141/layout/generic/nsGfxScrollFrame.cpp#6604-6605,6616-6617
Depends on D31409
Differential Revision: https://phabricator.services.mozilla.com/D31410
bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1552089
gecko-commit: 14743da36853e6b1d745418e128030b89bbb6fe2
gecko-integration-branch: autoland
gecko-reviewers: botond