Changeset 268499 in webkit

Timestamp:

Oct 14, 2020 4:55:58 PM (4 years ago)

Author:

Simon Fraser

Message:

Scrolls in the passive handler region should be reported as handled promptly
​https://bugs.webkit.org/show_bug.cgi?id=217718

Reviewed by Tim Horton.

The UI process will enqueue wheel events to send later if the WebContent process doesn't
promptly respond that it has handled the previous event. When scrolling in the passive
event region, we want the WebContent process to appear responsive, so respond to the UI
process when we've scrolled (which is before the event has been dispatched for DOM events).

Hard to test because CPU-constrained bots don't send wheel events in a predictable way.

• WebProcess/WebPage/EventDispatcher.cpp:

(WebKit::EventDispatcher::wheelEvent):

• WebProcess/WebPage/WebPage.cpp:

(WebKit::WebPage::wheelEvent):

Location:

trunk/Source/WebKit

Files:

• ChangeLog (modified) (1 diff)
• WebProcess/WebPage/EventDispatcher.cpp (modified) (1 diff)
• WebProcess/WebPage/WebPage.cpp (modified) (1 diff)

trunk/Source/WebKit/ChangeLog

@@ +1 @@
+2020-10-14  Simon Fraser  <simon.fraser@apple.com>
+
+        Scrolls in the passive handler region should be reported as handled promptly
+        https://bugs.webkit.org/show_bug.cgi?id=217718
+
+        Reviewed by Tim Horton.
+
+        The UI process will enqueue wheel events to send later if the WebContent process doesn't
+        promptly respond that it has handled the previous event. When scrolling in the passive
+        event region, we want the WebContent process to appear responsive, so respond to the UI
+        process when we've scrolled (which is before the event has been dispatched for DOM events).
+
+        Hard to test because CPU-constrained bots don't send wheel events in a predictable way.
+
+        * WebProcess/WebPage/EventDispatcher.cpp:
+        (WebKit::EventDispatcher::wheelEvent):
+        * WebProcess/WebPage/WebPage.cpp:
+        (WebKit::WebPage::wheelEvent):
+
 2020-10-14  Ryosuke Niwa  <rniwa@webkit.org>
 

trunk/Source/WebKit/WebProcess/WebPage/EventDispatcher.cpp

@@ -149 +149 @@
             if (result.needsMainThreadProcessing()) {
                 protectedThis->dispatchWheelEventViaMainThread(pageID, wheelEvent, result.steps);
-                return;
+                if (result.steps.contains(WheelEventProcessingSteps::MainThreadForScrolling))
+                    return;
             }
 
+            // If we scrolled on the scrolling thread (even if we send the event to the main thread for passive event handlers)
+            // respond to the UI process that the event was handled.
             protectedThis->sendDidReceiveEvent(pageID, wheelEvent.type(), result.wasHandled);
         });

trunk/Source/WebKit/WebProcess/WebPage/WebPage.cpp

@@ -2871 +2871 @@
     bool handled = handleWheelEvent(wheelEvent, m_page.get(), processingSteps);
 
-    send(Messages::WebPageProxy::DidReceiveEvent(static_cast<uint32_t>(wheelEvent.type()), handled));
+    if (processingSteps.contains(WheelEventProcessingSteps::MainThreadForScrolling))
+        send(Messages::WebPageProxy::DidReceiveEvent(static_cast<uint32_t>(wheelEvent.type()), handled));
 }