Commit 9405cbcc authored by Botond Ballo's avatar Botond Ballo
Browse files

Bug 1493742 - When accepting a layout viewport update from the main thread,... 

Bug 1493742 - When accepting a layout viewport update from the main thread, constrain its position to enclose the visual viewport. r=kats

APZ wants the *size* of the layout viewport from the main thread, but it
knows the position better.

Differential Revision: https://phabricator.services.mozilla.com/D9448

--HG--
extra : moz-landing-system : lando
parent b62d70d3

gfx/layers/apz/src/AsyncPanZoomController.cpp

+10 −0
Original line number Diff line number Diff line
@@ -4431,6 +4431,16 @@ void AsyncPanZoomController::NotifyLayersUpdated(const ScrollMetadata& aScrollMe 
    SmoothScrollTo(Metrics().GetSmoothScrollOffset());

  }



  if (viewportUpdated) {

    // While we want to accept the main thread's layout viewport _size_,

    // its position may be out of date in light of async scrolling, to

    // adjust it if necessary to make sure it continues to enclose the

    // visual viewport.

    // Note: it's important to do this _after_ we've accepted any

    // updated composition bounds.

    Metrics().RecalculateViewportOffset();

  }



  if (needContentRepaint) {

    // This repaint request is not driven by a user action on the APZ side

    RequestContentRepaint(false);