Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/core/frame/RootFrameViewport.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/frame/RootFrameViewport.h"
 
 #include "core/frame/FrameView.h"
 #include "core/layout/ScrollAlignment.h"
 #include "core/layout/ScrollAnchor.h"
 #include "platform/geometry/DoubleRect.h"
@@ skipping 191 matching lines @@
   ScrollableArea::setScrollOffset(clampedOffset, scrollType, scrollBehavior);
 }
 
 ScrollBehavior RootFrameViewport::scrollBehaviorStyle() const {
   return layoutViewport().scrollBehaviorStyle();
 }
 
 LayoutRect RootFrameViewport::scrollIntoView(const LayoutRect& rectInContent,
                                              const ScrollAlignment& alignX,
                                              const ScrollAlignment& alignY,
-                                             ScrollType scrollType) {
+                                             ScrollType scrollType,
+                                             ScrollBehavior scrollBehavior) {
   // We want to move the rect into the viewport that excludes the scrollbars so
   // we intersect the visual viewport with the scrollbar-excluded frameView
   // content rect. However, we don't use visibleContentRect directly since it
   // floors the scroll offset. Instead, we use ScrollAnimatorBase::currentOffset
   // and construct a LayoutRect from that.
   LayoutRect frameRectInContent =
       LayoutRect(FloatPoint(layoutViewport().scrollAnimator().currentOffset()),
                  FloatSize(layoutViewport().visibleContentRect().size()));
   LayoutRect visualRectInContent =
       LayoutRect(FloatPoint(scrollOffsetFromScrollAnimators()),
                  FloatSize(visualViewport().visibleContentRect().size()));
 
   // Intersect layout and visual rects to exclude the scrollbar from the view
   // rect.
   LayoutRect viewRectInContent =
       intersection(visualRectInContent, frameRectInContent);
   LayoutRect targetViewport = ScrollAlignment::getRectToExpose(
       viewRectInContent, rectInContent, alignX, alignY);
   if (targetViewport != viewRectInContent) {
-    setScrollOffset(ScrollOffset(targetViewport.x(), targetViewport.y()),
-                    scrollType);
+    if (scrollType == ProgrammaticScroll &&

[bokan, 2017/02/02 22:51:50]

Ditto here for DCHECK

[sunyunjia, 2017/02/10 23:25:20]

Done.

+        scrollBehavior == ScrollBehaviorSmooth) {
+      getProgrammaticScrollCoordinator()->queueAnimation(
+          this, ScrollOffset(targetViewport.x(), targetViewport.y()));
+    } else {
+      setScrollOffset(ScrollOffset(targetViewport.x(), targetViewport.y()),
+                      scrollType);
+    }
   }
 
   // RootFrameViewport only changes the viewport relative to the document so we
   // can't change the input rect's location relative to the document origin.
   return rectInContent;
 }
 
 void RootFrameViewport::updateScrollOffset(const ScrollOffset& offset,
                                            ScrollType scrollType) {
   distributeScrollBetweenViewports(offset, scrollType, ScrollBehaviorInstant,
@@ skipping 179 matching lines @@
 }
 
 bool RootFrameViewport::scrollAnimatorEnabled() const {
   return layoutViewport().scrollAnimatorEnabled();
 }
 
 HostWindow* RootFrameViewport::getHostWindow() const {
   return layoutViewport().getHostWindow();
 }
 
+ProgrammaticScrollCoordinator*
+RootFrameViewport::getProgrammaticScrollCoordinator() const {
+  return layoutViewport().getProgrammaticScrollCoordinator();
+}
+
 void RootFrameViewport::serviceScrollAnimations(double monotonicTime) {
   ScrollableArea::serviceScrollAnimations(monotonicTime);
   layoutViewport().serviceScrollAnimations(monotonicTime);
   visualViewport().serviceScrollAnimations(monotonicTime);
 }
 
 void RootFrameViewport::updateCompositorScrollAnimations() {
   ScrollableArea::updateCompositorScrollAnimations();
   layoutViewport().updateCompositorScrollAnimations();
   visualViewport().updateCompositorScrollAnimations();
@@ skipping 15 matching lines @@
   visualViewport().clearScrollableArea();
 }
 
 DEFINE_TRACE(RootFrameViewport) {
   visitor->trace(m_visualViewport);
   visitor->trace(m_layoutViewport);
   ScrollableArea::trace(visitor);
 }
 
 }  // namespace blink