1733742 - remove GetHighResolutionDisplayPort

Status: RESOLVED FIXED

(Core :: Panning and Zooming, enhancement)

Comment 1

[Timothy Nikkel (:tnikkel)]

Attachment: Bug 1733742. Remove GetHighResolutionDisplayPort. r?botond

With the old layers backend we had low precision buffer code controlled via the pref layers.low-precision-buffer that was used on android. We would expand the displayport by 4x and then paint it as 1/4 the resolution, and then we would have a critical displayport without the 4x multipler that we would paint at the real resolution. The code to do the painting at the lower resolution was in the layers backend and has since been removed. (This is okay because webrender doesn't rasterize all of the content in the displayport.) So the critical displayport or displayport are no longer treated differently anywhere. Except a few pieces of code that should be fixed/changed/removed. This patch being one of them.

GetHighResolutionDisplayPort would return the displayport without the multipler in all situations (pref on or off).

In DisplayPortUtils we are checking the displayport rect before/after setting new displayport margins to see if it changes to determine if we need to invalidate. Since the critical displayport isn't used for anything, the regular displayport is the correct thing to use here.

In nsGfxScrollFrame we are doing a similar thing, except checking that the displayport doesn't change after a scroll.

In nsDisplayListBuilder::OutOfFlowDisplayData::ComputeVisibleRectForFrame it's also the correct thing, as we want to include the same rect for fixed content as we do for non-fixed content. But this is an significant expansion of the dirty rect of fixed content and the code history has fixes related to drawing too much of fixed content and OOMing so a little more scrutiny is reasonable. However if there was a problem with OOM, since this is the same rect we use for non-fixed content we would have OOM problems with regular content, so this should be fine.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3864fbda86cb
Remove GetHighResolutionDisplayPort. r=botond

Comment 3

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/3864fbda86cb