[macOS] Issue load sooner on swipe back/forward navigation

https://bugs.webkit.org/show_bug.cgi?id=205087

Reviewed by Tim Horton.

Issue load sooner on swipe back/forward navigation on macOS. We were waiting until the end of
the swipe animation to issue the load. We now issue the load as soon as the user lifts the finger
off the screen and thus commits to navigating. This results in improved perceived performance
when swiping back/forward to navigate.

This patch does not take care of iOS because the ViewGestureController logic is different on that
platform. There is no reason we shouldn't be able to do the same optimization on iOS too though.

To achieve the behavior change on macOS, the following was done:
- Issue the load in ViewGestureController::willEndSwipeGesture() instead of
  ViewGestureController::endSwipeGesture().
- Add a new SnapshotRemovalTracker::Event::SwipeAnimationEnd event and wait for this event before
  taking away the snapshot. This makes sure we do not take away the swipe snapshot until the swipe
  animation is actually over (now that we start the navigation during the animation, instead of
  after).
- To make sure that layer being swiped away stays the same until the end of the animation, I added
  a new SwipeAnimation reason for freezing the layer tree. At the beginning of the animation, the
  UIProcess sends a FreezeLayerTreeDueToSwipeAnimation IPC to the WebProcess to add this layer tree
  freeze reason. At the end of the animation, the UIProcess sends the UnfreezeLayerTreeDueToSwipeAnimation
  IPC to remove this freeze reason. Without this change, the layer being swiped away would sometimes
  start showing the destination site being loaded before the end of the animation. On cross-process
  navigation, not freezing the layer tree would cause the swipe animation to get interrupted when
  we have something to paint in the new process before the end of the swipe animation.

* UIProcess/ProvisionalPageProxy.cpp:
(WebKit::ProvisionalPageProxy::initializeWebPage):
* UIProcess/ViewGestureController.cpp:
(WebKit::ViewGestureController::SnapshotRemovalTracker::eventsDescription):
(WebKit::ViewGestureController::willEndSwipeGesture):
(WebKit::ViewGestureController::endSwipeGesture):
* UIProcess/ViewGestureController.h:
* UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::commitProvisionalPage):
* UIProcess/WebPageProxy.h:
(WebKit::WebPageProxy::isLayerTreeFrozenDueToSwipeAnimation const):
* WebProcess/WebPage/WebPage.cpp:
(WebKit::WebPage::freezeLayerTreeDueToSwipeAnimation):
(WebKit::WebPage::unfreezeLayerTreeDueToSwipeAnimation):
* WebProcess/WebPage/WebPage.h:
* WebProcess/WebPage/WebPage.messages.in:


Canonical link: https://commits.webkit.org/218300@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@253360 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebKit/ChangeLog

@@ -1,3 +1,51 @@
+2019-12-10  Chris Dumez  <cdumez@apple.com>
+
+        [macOS] Issue load sooner on swipe back/forward navigation
+        https://bugs.webkit.org/show_bug.cgi?id=205087
+
+        Reviewed by Tim Horton.
+
+        Issue load sooner on swipe back/forward navigation on macOS. We were waiting until the end of
+        the swipe animation to issue the load. We now issue the load as soon as the user lifts the finger
+        off the screen and thus commits to navigating. This results in improved perceived performance
+        when swiping back/forward to navigate.
+
+        This patch does not take care of iOS because the ViewGestureController logic is different on that
+        platform. There is no reason we shouldn't be able to do the same optimization on iOS too though.
+
+        To achieve the behavior change on macOS, the following was done:
+        - Issue the load in ViewGestureController::willEndSwipeGesture() instead of
+          ViewGestureController::endSwipeGesture().
+        - Add a new SnapshotRemovalTracker::Event::SwipeAnimationEnd event and wait for this event before
+          taking away the snapshot. This makes sure we do not take away the swipe snapshot until the swipe
+          animation is actually over (now that we start the navigation during the animation, instead of
+          after).
+        - To make sure that layer being swiped away stays the same until the end of the animation, I added
+          a new SwipeAnimation reason for freezing the layer tree. At the beginning of the animation, the
+          UIProcess sends a FreezeLayerTreeDueToSwipeAnimation IPC to the WebProcess to add this layer tree
+          freeze reason. At the end of the animation, the UIProcess sends the UnfreezeLayerTreeDueToSwipeAnimation
+          IPC to remove this freeze reason. Without this change, the layer being swiped away would sometimes
+          start showing the destination site being loaded before the end of the animation. On cross-process
+          navigation, not freezing the layer tree would cause the swipe animation to get interrupted when
+          we have something to paint in the new process before the end of the swipe animation.
+
+        * UIProcess/ProvisionalPageProxy.cpp:
+        (WebKit::ProvisionalPageProxy::initializeWebPage):
+        * UIProcess/ViewGestureController.cpp:
+        (WebKit::ViewGestureController::SnapshotRemovalTracker::eventsDescription):
+        (WebKit::ViewGestureController::willEndSwipeGesture):
+        (WebKit::ViewGestureController::endSwipeGesture):
+        * UIProcess/ViewGestureController.h:
+        * UIProcess/WebPageProxy.cpp:
+        (WebKit::WebPageProxy::commitProvisionalPage):
+        * UIProcess/WebPageProxy.h:
+        (WebKit::WebPageProxy::isLayerTreeFrozenDueToSwipeAnimation const):
+        * WebProcess/WebPage/WebPage.cpp:
+        (WebKit::WebPage::freezeLayerTreeDueToSwipeAnimation):
+        (WebKit::WebPage::unfreezeLayerTreeDueToSwipeAnimation):
+        * WebProcess/WebPage/WebPage.h:
+        * WebProcess/WebPage/WebPage.messages.in:
+
 2019-12-10  Fujii Hironori  <Hironori.Fujii@sony.com>
 
         [Win] Fix MSVC warning C4701: potentially uninitialized local variable 'x' used

Source/WebKit/UIProcess/ProvisionalPageProxy.cpp

@@ -143,6 +143,9 @@ void ProvisionalPageProxy::initializeWebPage()
     parameters.isProcessSwap = true;
     m_process->send(Messages::WebProcess::CreateWebPage(m_webPageID, parameters), 0);
     m_process->addVisitedLinkStoreUser(m_page.visitedLinkStore(), m_page.identifier());
+
+    if (m_page.isLayerTreeFrozenDueToSwipeAnimation())
+        send(Messages::WebPage::FreezeLayerTreeDueToSwipeAnimation());
 }
 
 void ProvisionalPageProxy::loadData(API::Navigation& navigation, const IPC::DataReference& data, const String& MIMEType, const String& encoding, const String& baseURL, API::Object* userData, Optional<WebsitePoliciesData>&& websitePolicies)

Source/WebKit/UIProcess/ViewGestureController.cpp

@@ -278,6 +278,9 @@ String ViewGestureController::SnapshotRemovalTracker::eventsDescription(Events e
     if (event & ViewGestureController::SnapshotRemovalTracker::ScrollPositionRestoration)
         description.append("ScrollPositionRestoration ");
 
+    if (event & ViewGestureController::SnapshotRemovalTracker::SwipeAnimationEnd)
+        description.append("SwipeAnimationEnd ");
+
     return description.toString();
 }
 
@@ -553,42 +556,29 @@ void ViewGestureController::forceRepaintIfNeeded()
 void ViewGestureController::willEndSwipeGesture(WebBackForwardListItem& targetItem, bool cancelled)
 {
     m_webPageProxy.navigationGestureWillEnd(!cancelled, targetItem);
-}
-
-void ViewGestureController::endSwipeGesture(WebBackForwardListItem* targetItem, bool cancelled)
-{
-    ASSERT(m_activeGestureType == ViewGestureType::Swipe);
-    ASSERT(targetItem);
-
-#if PLATFORM(MAC)
-    m_swipeCancellationTracker = nullptr;
-#endif
 
-    if (cancelled) {
-        removeSwipeSnapshot();
-        m_webPageProxy.navigationGestureDidEnd(false, *targetItem);
+    if (cancelled)
         return;
-    }
 
     uint64_t renderTreeSize = 0;
-    if (ViewSnapshot* snapshot = targetItem->snapshot())
+    if (ViewSnapshot* snapshot = targetItem.snapshot())
         renderTreeSize = snapshot->renderTreeSize();
     auto renderTreeSizeThreshold = renderTreeSize * swipeSnapshotRemovalRenderTreeSizeTargetFraction;
 
-    m_webPageProxy.navigationGestureDidEnd(true, *targetItem);
-    m_webPageProxy.goToBackForwardItem(*targetItem);
+    m_webPageProxy.goToBackForwardItem(targetItem);
 
     auto* currentItem = m_webPageProxy.backForwardList().currentItem();
     // The main frame will not be navigated so hide the snapshot right away.
-    if (currentItem && currentItem->itemIsClone(*targetItem)) {
+    if (currentItem && currentItem->itemIsClone(targetItem)) {
         removeSwipeSnapshot();
         return;
     }
 
     SnapshotRemovalTracker::Events desiredEvents = SnapshotRemovalTracker::VisuallyNonEmptyLayout
         | SnapshotRemovalTracker::MainFrameLoad
         | SnapshotRemovalTracker::SubresourceLoads
-        | SnapshotRemovalTracker::ScrollPositionRestoration;
+        | SnapshotRemovalTracker::ScrollPositionRestoration
+        | SnapshotRemovalTracker::SwipeAnimationEnd;
 
     if (renderTreeSizeThreshold) {
         desiredEvents |= SnapshotRemovalTracker::RenderTreeSizeThreshold;
@@ -600,10 +590,30 @@ void ViewGestureController::endSwipeGesture(WebBackForwardListItem* targetItem,
     // FIXME: Like on iOS, we should ensure that even if one of the timeouts fires,
     // we never show the old page content, instead showing the snapshot background color.
 
-    if (ViewSnapshot* snapshot = targetItem->snapshot())
+    if (ViewSnapshot* snapshot = targetItem.snapshot())
         m_backgroundColorForCurrentSnapshot = snapshot->backgroundColor();
 }
 
+void ViewGestureController::endSwipeGesture(WebBackForwardListItem* targetItem, bool cancelled)
+{
+    ASSERT(m_activeGestureType == ViewGestureType::Swipe);
+    ASSERT(targetItem);
+
+#if PLATFORM(MAC)
+    m_swipeCancellationTracker = nullptr;
+#endif
+
+    if (cancelled) {
+        removeSwipeSnapshot();
+        m_webPageProxy.navigationGestureDidEnd(false, *targetItem);
+        return;
+    }
+
+    m_webPageProxy.navigationGestureDidEnd(true, *targetItem);
+
+    m_snapshotRemovalTracker.eventOccurred(SnapshotRemovalTracker::SwipeAnimationEnd);
+}
+
 void ViewGestureController::requestRenderTreeSizeNotificationIfNeeded()
 {
     if (!m_snapshotRemovalTracker.hasOutstandingEvent(SnapshotRemovalTracker::RenderTreeSizeThreshold))

Source/WebKit/UIProcess/ViewGestureController.h

@@ -194,7 +194,8 @@ class ViewGestureController : private IPC::MessageReceiver {
             RepaintAfterNavigation = 1 << 2,
             MainFrameLoad = 1 << 3,
             SubresourceLoads = 1 << 4,
-            ScrollPositionRestoration = 1 << 5
+            ScrollPositionRestoration = 1 << 5,
+            SwipeAnimationEnd = 1 << 6
         };
         typedef uint8_t Events;
 

Source/WebKit/UIProcess/WebPageProxy.cpp

@@ -3122,6 +3122,9 @@ void WebPageProxy::commitProvisionalPage(FrameIdentifier frameID, uint64_t navig
         shouldDelayClosingUntilEnteringAcceleratedCompositingMode = ShouldDelayClosingUntilEnteringAcceleratedCompositingMode::Yes;
 #endif
 
+    if (m_isLayerTreeFrozenDueToSwipeAnimation)
+        send(Messages::WebPage::UnfreezeLayerTreeDueToSwipeAnimation());
+
     processDidTerminate(ProcessTerminationReason::NavigationSwap);
 
     m_process->removeMessageReceiver(Messages::WebPageProxy::messageReceiverName(), m_webPageID);
@@ -8417,6 +8420,10 @@ void WebPageProxy::navigationGestureDidBegin()
 void WebPageProxy::navigationGestureWillEnd(bool willNavigate, WebBackForwardListItem& item)
 {
     PageClientProtector protector(pageClient());
+    if (willNavigate) {
+        m_isLayerTreeFrozenDueToSwipeAnimation = true;
+        send(Messages::WebPage::FreezeLayerTreeDueToSwipeAnimation());
+    }
 
     pageClient().navigationGestureWillEnd(willNavigate, item);
 
@@ -8430,6 +8437,11 @@ void WebPageProxy::navigationGestureDidEnd(bool willNavigate, WebBackForwardList
     pageClient().navigationGestureDidEnd(willNavigate, item);
 
     m_navigationClient->didEndNavigationGesture(*this, willNavigate, item);
+
+    if (m_isLayerTreeFrozenDueToSwipeAnimation) {
+        m_isLayerTreeFrozenDueToSwipeAnimation = false;
+        send(Messages::WebPage::UnfreezeLayerTreeDueToSwipeAnimation());
+    }
 }
 
 void WebPageProxy::navigationGestureDidEnd()

Source/WebKit/UIProcess/WebPageProxy.h

@@ -1290,6 +1290,8 @@ class WebPageProxy : public API::ObjectImpl<API::Object::Type::Page>
     void endColorPicker();
 #endif
 
+    bool isLayerTreeFrozenDueToSwipeAnimation() const { return m_isLayerTreeFrozenDueToSwipeAnimation; }
+
     WebCore::IntSize minimumSizeForAutoLayout() const { return m_minimumSizeForAutoLayout; }
     void setMinimumSizeForAutoLayout(const WebCore::IntSize&);
 
@@ -2639,6 +2641,7 @@ class WebPageProxy : public API::ObjectImpl<API::Object::Type::Page>
     COMPtr<ID3D11Device1> m_device;
 #endif
     bool m_isQuotaIncreaseDenied { false };
+    bool m_isLayerTreeFrozenDueToSwipeAnimation { false };
 
     String m_overriddenMediaType;
 

Source/WebKit/WebProcess/WebPage/WebPage.cpp

@@ -4665,6 +4665,16 @@ void WebPage::effectiveAppearanceDidChange(bool useDarkAppearance, bool useEleva
 }
 #endif
 
+void WebPage::freezeLayerTreeDueToSwipeAnimation()
+{
+    freezeLayerTree(LayerTreeFreezeReason::SwipeAnimation);
+}
+
+void WebPage::unfreezeLayerTreeDueToSwipeAnimation()
+{
+    unfreezeLayerTree(LayerTreeFreezeReason::SwipeAnimation);
+}
+
 void WebPage::beginPrinting(FrameIdentifier frameID, const PrintInfo& printInfo)
 {
     WebFrame* frame = WebProcess::singleton().webFrame(frameID);

Source/WebKit/WebProcess/WebPage/WebPage.h

@@ -729,13 +729,17 @@ class WebPage : public API::ObjectImpl<API::Object::Type::BundlePage>, public IP
         PageSuspended           = 1 << 3,
         Printing                = 1 << 4,
         ProcessSwap             = 1 << 5,
+        SwipeAnimation          = 1 << 6,
     };
     void freezeLayerTree(LayerTreeFreezeReason);
     void unfreezeLayerTree(LayerTreeFreezeReason);
 
     void markLayersVolatile(Function<void(bool)>&& completionHandler = { });
     void cancelMarkLayersVolatile();
 
+    void freezeLayerTreeDueToSwipeAnimation();
+    void unfreezeLayerTreeDueToSwipeAnimation();
+
     NotificationPermissionRequestManager* notificationPermissionRequestManager();
 
     void pageDidScroll();

Source/WebKit/WebProcess/WebPage/WebPage.messages.in

@@ -380,6 +380,9 @@ GenerateSyntheticEditingCommand(enum:uint8_t WebKit::SyntheticEditingCommandType
     # Notification
     DidReceiveNotificationPermissionDecision(uint64_t notificationID, bool allowed)
 
+    FreezeLayerTreeDueToSwipeAnimation()
+    UnfreezeLayerTreeDueToSwipeAnimation()
+
     # Printing.
     BeginPrinting(WebCore::FrameIdentifier frameID, struct WebKit::PrintInfo printInfo)
     EndPrinting()