828345 - Fixed position elements jitter when snapping back from zooming out beyond page bounds

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: Toolbar, defect)

Description

[Chris Lord [:cwiiis]]

If you zoom out so that there is blank area on both sides of an axis, then let go, there are usually a few frames where the fixed position elements will appear to jump position. This is because the clamping scroll-port does not maintain aspect ratio in these situations. Patch incoming.

Comment 1

[Chris Lord [:cwiiis]]

Attachment: Maintain clamping scrollport aspect ratio

Comment 2

[Kartikaya Gupta (email:[e-mail])]

Comment on attachment 699824 [details] [diff] [review]
Maintain clamping scrollport aspect ratio

Review of attachment 699824 [details] [diff] [review]:
-----------------------------------------------------------------

LGTM

::: mobile/android/chrome/content/browser.js
@@ +3134,5 @@
>      let [pageWidth, pageHeight] = this.getPageSize(this.browser.contentDocument,
>                                                     viewportWidth, viewportHeight);
> +
> +    let factor = Math.min(viewportWidth / gScreenWidth, pageWidth / gScreenWidth,
> +                          viewportHeight / gScreenHeight, pageHeight / gScreenHeight);

I would prefer renaming "factor" to "scrollPortAspectRatio" or adding a comment. Also I didn't know Math.min could take an arbitrary number of arguments, cool!

Comment 3

[Chris Lord [:cwiiis]]

Added comment, pushed to inbound:

https://hg.mozilla.org/integration/mozilla-inbound/rev/1f3d5f4cc05c

Comment 4

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/1f3d5f4cc05c

Comment 5

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/1f3d5f4cc05c

Comment 6

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/1f3d5f4cc05c