Move viewport actions into an ApplyScroll callback.

third_party/WebKit/Source/core/input/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 146 matching lines @@
 // we'd like to EventHandler::handleMousePressEvent to pass the event to the widget and thus the
 // event target node can't still be the shadow node.
 bool shouldRefetchEventTarget(const MouseEventWithHitTestResults& mev)
 {
     Node* targetNode = mev.innerNode();
     if (!targetNode || !targetNode->parentNode())
         return true;
     return targetNode->isShadowRoot() && isHTMLInputElement(*toShadowRoot(targetNode)->host());
 }
 
+// TODO(bokan): This method can go away once all scrolls happen through the
+// scroll customization path.
+void computeScrollChainForSingleNode(Node& node, std::deque<int>& scrollChain)
+{
+    scrollChain.clear();
+
+    ASSERT(node.layoutObject());
+    Element* element = toElement(&node);
+
+    scrollChain.push_front(DOMNodeIds::idForNode(element));
+}
+
+void recomputeScrollChain(const LocalFrame& frame, const Node& startNode,
+    std::deque<int>& scrollChain)
+{
+    scrollChain.clear();
+
+    ASSERT(startNode.layoutObject());
+    LayoutBox* curBox = startNode.layoutObject()->enclosingBox();
+
+    // Scrolling propagates along the containing block chain.
+    while (curBox && !curBox->isLayoutView()) {
+        Node* curNode = curBox->node();
+        // FIXME: this should reject more elements, as part of crbug.com/410974.
+        if (curNode && curNode->isElementNode()) {
+            Element* curElement = toElement(curNode);
+            if (curElement == frame.document()->scrollingElement())
+                break;
+            scrollChain.push_front(DOMNodeIds::idForNode(curElement));
+        }
+        curBox = curBox->containingBlock();
+    }
+    // TODO(tdresser): this should sometimes be excluded, as part of crbug.com/410974.
+    // We need to ensure that the scrollingElement is always part of
+    // the scroll chain. In quirks mode, when the scrollingElement is
+    // the body, some elements may use the documentElement as their
+    // containingBlock, so we ensure the scrollingElement is added
+    // here.
+    scrollChain.push_front(DOMNodeIds::idForNode(frame.document()->scrollingElement()));
+}
+
 } // namespace
 
 using namespace HTMLNames;
 
 // The link drag hysteresis is much larger than the others because there
 // needs to be enough space to cancel the link press without starting a link drag,
 // and because dragging links is rare.
 static const int LinkDragHysteresis = 40;
 static const int ImageDragHysteresis = 5;
 static const int TextDragHysteresis = 3;
@@ skipping 38 matching lines @@
     OptionalCursor(const Cursor& cursor) : m_isCursorChange(true), m_cursor(cursor) { }
 
     bool isCursorChange() const { return m_isCursorChange; }
     const Cursor& cursor() const { ASSERT(m_isCursorChange); return m_cursor; }
 
 private:
     bool m_isCursorChange;
     Cursor m_cursor;
 };
 
-void recomputeScrollChain(const LocalFrame& frame, const Node& startNode,
-    std::deque<int>& scrollChain)
-{
-    scrollChain.clear();
-
-    ASSERT(startNode.layoutObject());
-    LayoutBox* curBox = startNode.layoutObject()->enclosingBox();
-
-    // Scrolling propagates along the containing block chain.
-    while (curBox && !curBox->isLayoutView()) {
-        Node* curNode = curBox->node();
-        // FIXME: this should reject more elements, as part of crbug.com/410974.
-        if (curNode && curNode->isElementNode()) {
-            Element* curElement = toElement(curNode);
-            if (curElement == frame.document()->scrollingElement())
-                break;
-            scrollChain.push_front(DOMNodeIds::idForNode(curElement));
-        }
-        curBox = curBox->containingBlock();
-    }
-    // TODO(tdresser): this should sometimes be excluded, as part of crbug.com/410974.
-    // We need to ensure that the scrollingElement is always part of
-    // the scroll chain. In quirks mode, when the scrollingElement is
-    // the body, some elements may use the documentElement as their
-    // containingBlock, so we ensure the scrollingElement is added
-    // here.
-    scrollChain.push_front(DOMNodeIds::idForNode(frame.document()->scrollingElement()));
-}
-
 EventHandler::EventHandler(LocalFrame* frame)
     : m_frame(frame)
     , m_mousePressed(false)
     , m_capturesDragging(false)
     , m_mouseDownMayStartDrag(false)
     , m_selectionController(SelectionController::create(*frame))
     , m_hoverTimer(this, &EventHandler::hoverTimerFired)
     , m_cursorUpdateTimer(this, &EventHandler::cursorUpdateTimerFired)
     , m_mouseDownMayStartAutoscroll(false)
     , m_fakeMouseMoveEventTimer(this, &EventHandler::fakeMouseMoveEventTimerFired)
@@ skipping 340 matching lines @@
 
     return result;
 }
 
 void EventHandler::stopAutoscroll()
 {
     if (AutoscrollController* controller = autoscrollController())
         controller->stopAutoscroll();
 }
 
-ScrollResult EventHandler::physicalScroll(ScrollGranularity granularity, const FloatSize& delta, Node* startNode, Node** stopNode, bool* consumed)
+ScrollResult EventHandler::scrollBox(LayoutBox* box,
+    ScrollGranularity granularity, const FloatSize& delta,
+    const FloatPoint& position, const FloatSize& velocity,
+    bool* wasRootScroller)
+{
+    ASSERT(box);
+    Node* node = box->node();
+    Document* document = m_frame->document();
+    Element* scrollingElement = document->scrollingElement();
+
+    bool isRootFrame = !document->ownerElement();
+
+    // TODO(bokan): If the applyScroll is installed on the body, we can still

[tdresser, 2016/04/12 13:59:15]

"the applyScroll" doesn't necessarily refer to a unique callback.

[bokan, 2016/04/12 15:13:53]

Changed "applyScroll" to "ViewportScrollCallback" which is more accurate.

+    // hit the HTML element for scrolling in which case it'll bubble up to the
+    // document node and try to scroll the LayoutView directly. Make sure we
+    // never scroll the LayoutView like this by manually resetting the scroll to
+    // happen on the scrolling element. This can also happen in QuirksMode when
+    // the body is scrollable and scrollingElement == nullptr.
+    if (node && node->isDocumentNode() && isRootFrame) {
+        node = scrollingElement
+            ? scrollingElement
+            : document->documentElement();
+    }
+
+    // If there's no ApplyScroll callback on the element, scroll as usuall in
+    // the non-scroll-customization case.
+    if (!node || !node->isElementNode() || !toElement(node)->getApplyScroll()) {
+        ASSERT(!isRootFrame
+            || node != scrollingElement
+            || (!scrollingElement && node != document->documentElement()));
+        *wasRootScroller = false;
+        return box->scroll(granularity, delta);
+    }
+
+    ASSERT(isRootFrame);
+
+    // If there is an ApplyScroll callback, its because we placed one on the
+    // root scroller to control top controls and overscroll. Invoke a scroll
+    // using parts of the scroll customization framework on just this element.
+    computeScrollChainForSingleNode(*node, m_currentScrollChain);
+
+    OwnPtr<ScrollStateData> scrollStateData = adoptPtr(new ScrollStateData());
+    scrollStateData->delta_x = delta.width();
+    scrollStateData->delta_y = delta.height();
+    scrollStateData->start_position_x = position.x();
+    scrollStateData->start_position_y = position.y();
+    // TODO(bokan): delta_granularity is meant to be the number of pixels per
+    // unit of delta but we can't determine that until we get to the area we'll
+    // scroll. This is a hack, we stuff the enum into the double value for
+    // now.
+    scrollStateData->delta_granularity = static_cast<double>(granularity);
+    scrollStateData->velocity_x = velocity.width();
+    scrollStateData->velocity_y = velocity.height();
+    scrollStateData->should_propagate = false;
+    scrollStateData->is_in_inertial_phase = false;
+    scrollStateData->from_user_input = true;
+    scrollStateData->delta_consumed_for_scroll_sequence = false;
+    ScrollState* scrollState =
+        ScrollState::create(scrollStateData.release());
+
+    customizedScroll(*node, *scrollState);
+
+    ScrollResult result(
+        scrollState->deltaX() != delta.width(),
+        scrollState->deltaY() != delta.height(),
+        scrollState->deltaX(),
+        scrollState->deltaY());
+
+    *wasRootScroller = true;
+    m_currentScrollChain.clear();
+
+    return result;
+}
+
+ScrollResult EventHandler::physicalScroll(ScrollGranularity granularity,
+    const FloatSize& delta, const FloatPoint& position,
+    const FloatSize& velocity, Node* startNode, Node** stopNode, bool* consumed)
 {
     if (consumed)
         *consumed = false;
     if (delta.isZero())
         return ScrollResult();
 
     Node* node = startNode;
     ASSERT(node && node->layoutObject());
 
     m_frame->document()->updateLayoutIgnorePendingStylesheets();
 
     ScrollResult result;
 
     LayoutBox* curBox = node->layoutObject()->enclosingBox();
     while (curBox) {
         // If we're at the stopNode, we should try to scroll it but we shouldn't
         // chain past it.
         bool shouldStopChaining =
             stopNode && *stopNode && curBox->node() == *stopNode;
-        result = curBox->scroll(granularity, delta);
+        bool wasRootScroller = false;
+
+        result = scrollBox(
+            curBox,
+            granularity,
+            delta,
+            position,
+            velocity,
+            &wasRootScroller);
 
         if (result.didScroll() && stopNode)
             *stopNode = curBox->node();
 
         if (result.didScroll() || shouldStopChaining) {
             setFrameWasScrolledByUser();
             if (consumed)
                 *consumed = true;
             return result;
+        } else if (wasRootScroller) {
+            // Don't try to chain past the root scroller, even if there's
+            // eligible ancestors.
+            break;
         }
 
         curBox = curBox->containingBlock();
     }
 
     return result;
 }
 
 bool EventHandler::logicalScroll(ScrollDirection direction, ScrollGranularity granularity, Node* startNode)
 {
@@ skipping 1233 matching lines @@
     // TODO(bokan): This seems like it belongs in the coalescing logic.
     if (granularity == ScrollByPage) {
         if (delta.width())
             delta.setWidth(delta.width() > 0 ? 1 : -1);
         if (delta.height())
             delta.setHeight(delta.height() > 0 ? 1 : -1);
     }
 
     // FIXME: enable scroll customization in this case. See crbug.com/410974.
     bool consumed = false;
-    ScrollResult result = physicalScroll(granularity, delta, startNode, &node, &consumed);
+
+    physicalScroll(
+        granularity,
+        delta,
+        FloatPoint(),
+        FloatSize(),
+        startNode,
+        &node,
+        &consumed);
 
     if (consumed)
         wheelEvent->setDefaultHandled();
-
-    if (m_frame->isMainFrame())
-        handleOverscroll(result);
 }
 
 WebInputEventResult EventHandler::handleGestureShowPress()
 {
     m_lastShowPressTimestamp = WTF::monotonicallyIncreasingTime();
 
     FrameView* view = m_frame->view();
     if (!view)
         return WebInputEventResult::NotHandled;
     if (ScrollAnimatorBase* scrollAnimator = view->existingScrollAnimator())
@@ skipping 465 matching lines @@
 
     FloatSize unusedDelta(scrollResult.unusedScrollDeltaX, scrollResult.unusedScrollDeltaY);
     unusedDelta = adjustOverscroll(unusedDelta);
     resetOverscroll(scrollResult.didScrollX, scrollResult.didScrollY);
     if (unusedDelta != FloatSize()) {
         m_accumulatedRootOverscroll += unusedDelta;
         m_frame->chromeClient().didOverscroll(unusedDelta, m_accumulatedRootOverscroll, position, velocity);
     }
 }
 
+bool EventHandler::isRootScroller(const Node& node) const
+{
+    // The root scroller is the one Element on the page designated to perform
+    // "viewport actions" like top controls movement and overscroll glow.
+
+    if (!node.isElementNode() || node.document().ownerElement())
+        return false;
+
+    Element* scrollingElement = node.document().scrollingElement();
+    return scrollingElement
+        ? toElement(&node) == node.document().scrollingElement()
+        : toElement(&node) == node.document().documentElement();
+}
+
 WebInputEventResult EventHandler::handleGestureScrollUpdate(const PlatformGestureEvent& gestureEvent)
 {
     ASSERT(gestureEvent.type() == PlatformEvent::GestureScrollUpdate);
 
     // Negate the deltas since the gesture event stores finger movement and
     // scrolling occurs in the direction opposite the finger's movement
     // direction. e.g. Finger moving up has negative event delta but causes the
     // page to scroll down causing positive scroll delta.
     FloatSize delta(-gestureEvent.deltaX(), -gestureEvent.deltaY());
     FloatSize velocity(-gestureEvent.velocityX(), -gestureEvent.velocityY());
@@ skipping 22 matching lines @@
             // FIXME: we should allow simultaneous scrolling of nested
             // iframes along perpendicular axes. See crbug.com/466991.
             m_deltaConsumedForScrollSequence = true;
             return result;
         }
 
         if (handleScrollCustomization) {
             OwnPtr<ScrollStateData> scrollStateData = adoptPtr(new ScrollStateData());
             scrollStateData->delta_x = delta.width();
             scrollStateData->delta_y = delta.height();
+            scrollStateData->delta_granularity = ScrollByPrecisePixel;
             scrollStateData->velocity_x = velocity.width();
             scrollStateData->velocity_y = velocity.height();
             scrollStateData->should_propagate = !gestureEvent.preventPropagation();
             scrollStateData->is_in_inertial_phase = gestureEvent.inertial();
             scrollStateData->from_user_input = true;
             scrollStateData->delta_consumed_for_scroll_sequence = m_deltaConsumedForScrollSequence;
             ScrollState* scrollState = ScrollState::create(scrollStateData.release());
             if (m_previousGestureScrolledNode) {
                 // The ScrollState needs to know what the current
                 // native scrolling element is, so that for an
                 // inertial scroll that shouldn't propagate, only the
                 // currently scrolling element responds.
                 ASSERT(m_previousGestureScrolledNode->isElementNode());
                 scrollState->setCurrentNativeScrollingElement(toElement(m_previousGestureScrolledNode.get()));
             }
             customizedScroll(*node, *scrollState);
             m_previousGestureScrolledNode = scrollState->currentNativeScrollingElement();
             m_deltaConsumedForScrollSequence = scrollState->deltaConsumedForScrollSequence();
             if (scrollState->deltaX() != delta.width()
                 || scrollState->deltaY() != delta.height()) {
                 setFrameWasScrolledByUser();
                 return WebInputEventResult::HandledSystem;
             }
         } else {
             Node* stopNode = nullptr;
             if (gestureEvent.preventPropagation())
                 stopNode = m_previousGestureScrolledNode.get();
 
             bool consumed = false;
-            ScrollResult result = physicalScroll(granularity, delta, node, &stopNode, &consumed);
+            ScrollResult result = physicalScroll(
+                granularity,
+                delta,
+                FloatPoint(gestureEvent.position()),
+                velocity,
+                node,
+                &stopNode,
+                &consumed);
 
             if (gestureEvent.preventPropagation())
                 m_previousGestureScrolledNode = stopNode;
 
-            if (m_frame->isMainFrame() && (!stopNode || stopNode->layoutObject() == m_frame->view()->layoutView())) {
-                FloatPoint position = FloatPoint(gestureEvent.position().x(), gestureEvent.position().y());
-                handleOverscroll(result, position, velocity);
-            } else {
+            if (!stopNode || !isRootScroller(*stopNode))
                 resetOverscroll(result.didScrollX, result.didScrollY);
-            }
 
             if (consumed)
                 return WebInputEventResult::HandledSystem;
         }
     }
 
     return WebInputEventResult::NotHandled;
 }
 
 void EventHandler::clearGestureScrollState()
@@ skipping 1532 matching lines @@
 PlatformEvent::Modifiers EventHandler::accessKeyModifiers()
 {
 #if OS(MACOSX)
     return static_cast<PlatformEvent::Modifiers>(PlatformEvent::CtrlKey | PlatformEvent::AltKey);
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace blink