Bug 210216 - Generate event region for every root layer
Summary: Generate event region for every root layer
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: WebCore Misc. (show other bugs)
Version: WebKit Local Build
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2020-04-08 15:19 PDT by Daniel Bates
Modified: 2020-04-25 21:03 PDT (History)
1 user (show)

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Description Daniel Bates 2020-04-08 15:19:39 PDT 
RenderLayer::invalidateEventRegion() and RenderLayerBacking::updateEventRegion() only generate an event region for non-root layers so the UI process has more info for hit testing.
Comment 1 Daniel Bates 2020-04-08 15:22:13 PDT 
This bug came up while considering alt patch attachment #395855 [details] (bug 210041). It removed an iOS compile-time guard from RenderLayer::invalidateEventRegion(), which made causes this progression:

[[
--- /Volumes/Data/worker/macOS-Mojave-Release-WK2-Tests-EWS/build/layout-test-results/fast/scrolling/mac/event-region-subframe-expected.txt
+++ /Volumes/Data/worker/macOS-Mojave-Release-WK2-Tests-EWS/build/layout-test-results/fast/scrolling/mac/event-region-subframe-actual.txt
@@ -6,6 +6,9 @@
     (GraphicsLayer
       (bounds 800.00 600.00)
       (contentsOpaque 1)
+      (event region
+        (rect (0,0) width=800 height=600)
+      )
       (children 1
         (GraphicsLayer
           (position 8.00 8.00)
]]