Implement CSS: scroll-boundary-behavior

third_party/WebKit/Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc.
  * All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
@@ skipping 510 matching lines @@
       scroll_state.DeltaConsumedForScrollSequence() &&
       scroll_state.CurrentNativeScrollingElement() != this) {
     return;
   }
 
   const double delta_x = scroll_state.deltaX();
   const double delta_y = scroll_state.deltaY();
 
   CallApplyScroll(scroll_state);
 
-  if (delta_x != scroll_state.deltaX() || delta_y != scroll_state.deltaY())
+  if (delta_x != scroll_state.deltaX() || delta_y != scroll_state.deltaY()) {
     scroll_state.SetCurrentNativeScrollingElement(this);
+  }

[bokan, 2017/05/19 19:35:57]

Nit: no braces

[sunyunjia, 2017/05/25 20:07:10]

Done.

 }
 
 void Element::CallDistributeScroll(ScrollState& scroll_state) {
   ScrollStateCallback* callback =
       GetScrollCustomizationCallbacks().GetDistributeScroll(this);
 
   // TODO(bokan): Need to add tests before we allow calling custom callbacks
   // for non-touch modalities. For now, just call into the native callback but
   // allow the viewport scroll callback so we don't disable overscroll.
   // crbug.com/623079.
@@ skipping 43 matching lines @@
 
   if (!box_to_scroll)
     return;
 
   ScrollResult result = LayoutBoxItem(box_to_scroll)
                             .EnclosingBox()
                             .Scroll(ScrollGranularity(static_cast<int>(
                                         scroll_state.deltaGranularity())),
                                     delta);
 
-  if (!result.DidScroll())
+  if (!result.DidScroll()) {
+    if (GetComputedStyle()->ScrollBoundaryBehaviorX() !=

[bokan, 2017/05/19 19:35:57]

Similarly, this should be done at the time that we compute the scroll chain in
ScrollManager::RecomputeScrollChain

[sunyunjia, 2017/05/25 20:07:10]

Done.

+            EScrollBoundaryBehavior::kAuto &&
+        std::abs(delta.Width()) > std::abs(delta.Height()))
+      scroll_state.ConsumeDeltaNative(delta.Width(), 0);
+    if (GetComputedStyle()->ScrollBoundaryBehaviorY() !=
+            EScrollBoundaryBehavior::kAuto &&
+        std::abs(delta.Height()) > std::abs(delta.Width()))
+      scroll_state.ConsumeDeltaNative(0, delta.Height());
     return;
+  }
 
   // FIXME: Native scrollers should only consume the scroll they
   // apply. See crbug.com/457765.
   scroll_state.ConsumeDeltaNative(delta.Width(), delta.Height());
 
   // We need to setCurrentNativeScrollingElement in both the
   // distributeScroll and applyScroll default implementations so
   // that if JS overrides one of these methods, but not the
   // other, this bookkeeping remains accurate.
   scroll_state.SetCurrentNativeScrollingElement(this);
@@ skipping 3740 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(Element) {
   if (HasRareData()) {
     visitor->TraceWrappers(GetElementRareData());
   }
   ContainerNode::TraceWrappers(visitor);
 }
 
 }  // namespace blink