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(clamped_offset, scroll_type, scroll_behavior);
 }
 
 ScrollBehavior RootFrameViewport::ScrollBehaviorStyle() const {
   return LayoutViewport().ScrollBehaviorStyle();
 }
 
 LayoutRect RootFrameViewport::ScrollIntoView(const LayoutRect& rect_in_content,
                                              const ScrollAlignment& align_x,
                                              const ScrollAlignment& align_y,
+                                             bool is_smooth,
                                              ScrollType scroll_type) {
   // 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 frame_rect_in_content = LayoutRect(
       FloatPoint(LayoutViewport().GetScrollAnimator().CurrentOffset()),
       FloatSize(LayoutViewport().VisibleContentRect().Size()));
   LayoutRect visual_rect_in_content =
       LayoutRect(FloatPoint(ScrollOffsetFromScrollAnimators()),
                  FloatSize(VisualViewport().VisibleContentRect().Size()));
 
   // Intersect layout and visual rects to exclude the scrollbar from the view
   // rect.
   LayoutRect view_rect_in_content =
       Intersection(visual_rect_in_content, frame_rect_in_content);
   LayoutRect target_viewport = ScrollAlignment::GetRectToExpose(
       view_rect_in_content, rect_in_content, align_x, align_y);
   if (target_viewport != view_rect_in_content) {
-    SetScrollOffset(ScrollOffset(target_viewport.X(), target_viewport.Y()),
-                    scroll_type);
+    ScrollOffset target_offset(target_viewport.X(), target_viewport.Y());
+    if (is_smooth) {
+      DCHECK(scroll_type == kProgrammaticScroll);
+      GetSmoothScrollSequencer()->QueueAnimation(this, target_offset);
+    } else {
+      SetScrollOffset(target_offset, scroll_type);
+    }
   }
 
   // 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 rect_in_content;
 }
 
 void RootFrameViewport::UpdateScrollOffset(const ScrollOffset& offset,
                                            ScrollType scroll_type) {
   DistributeScrollBetweenViewports(offset, scroll_type, kScrollBehaviorInstant,
@@ skipping 180 matching lines @@
 }
 
 bool RootFrameViewport::ScrollAnimatorEnabled() const {
   return LayoutViewport().ScrollAnimatorEnabled();
 }
 
 PlatformChromeClient* RootFrameViewport::GetChromeClient() const {
   return LayoutViewport().GetChromeClient();
 }
 
+bool RootFrameViewport::ScheduleAnimation() {
+  return LayoutViewport().ScheduleAnimation();
+}
+
+SmoothScrollSequencer* RootFrameViewport::GetSmoothScrollSequencer() const {
+  return LayoutViewport().GetSmoothScrollSequencer();
+}
+
 void RootFrameViewport::ServiceScrollAnimations(double monotonic_time) {
   ScrollableArea::ServiceScrollAnimations(monotonic_time);
   LayoutViewport().ServiceScrollAnimations(monotonic_time);
   VisualViewport().ServiceScrollAnimations(monotonic_time);
 }
 
 void RootFrameViewport::UpdateCompositorScrollAnimations() {
   ScrollableArea::UpdateCompositorScrollAnimations();
   LayoutViewport().UpdateCompositorScrollAnimations();
   VisualViewport().UpdateCompositorScrollAnimations();
@@ skipping 11 matching lines @@
   VisualViewport().ClearScrollableArea();
 }
 
 DEFINE_TRACE(RootFrameViewport) {
   visitor->Trace(visual_viewport_);
   visitor->Trace(layout_viewport_);
   ScrollableArea::Trace(visitor);
 }
 
 }  // namespace blink