Update the snap points css properties

third_party/WebKit/Source/core/page/scrolling/SnapCoordinator.cpp

 // Copyright 2016 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 "SnapCoordinator.h"
 
 #include "core/dom/Element.h"
 #include "core/dom/Node.h"
 #include "core/dom/NodeComputedStyle.h"
 #include "core/layout/LayoutBlock.h"
@@ skipping 25 matching lines @@
          box->GetNode() != viewport_defining_element)
     box = box->ContainingBlock();
 
   // If we reach to viewportDefiningElement then we dispatch to viewport
   if (box && box->GetNode() == viewport_defining_element)
     return snap_area.GetDocument().GetLayoutView();
 
   return box;
 }
 
-void SnapCoordinator::SnapAreaDidChange(
-    LayoutBox& snap_area,
-    const Vector<LengthPoint>& snap_coordinates) {
-  if (snap_coordinates.IsEmpty()) {
+void SnapCoordinator::SnapAreaDidChange(LayoutBox& snap_area,
+                                        ScrollSnapAlign scroll_snap_align) {
+  if (scroll_snap_align.alignmentX == kSnapAlignmentNone &&
+      scroll_snap_align.alignmentY == kSnapAlignmentNone) {
     snap_area.SetSnapContainer(nullptr);
     return;
   }
 
   if (LayoutBox* snap_container = FindSnapContainer(snap_area)) {
     snap_area.SetSnapContainer(snap_container);
   } else {
     // TODO(majidvp): keep track of snap areas that do not have any
     // container so that we check them again when a new container is
     // added to the page.
   }
 }
 
 void SnapCoordinator::SnapContainerDidChange(LayoutBox& snap_container,
                                              ScrollSnapType scroll_snap_type) {
-  if (scroll_snap_type == kScrollSnapTypeNone) {
+  if (scroll_snap_type.is_none) {
     // TODO(majidvp): Track and report these removals to CompositorWorker
     // instance responsible for snapping
     snap_containers_.erase(&snap_container);
     snap_container.ClearSnapAreas();
   } else {
     snap_containers_.insert(&snap_container);
   }
 
   // TODO(majidvp): Add logic to correctly handle orphaned snap areas here.
   // 1. Removing container: find a new snap container for its orphan snap
   // areas (most likely nearest ancestor of current container) otherwise add
   // them to an orphan list.
   // 2. Adding container: may take over snap areas from nearest ancestor snap
   // container or from existing areas in orphan pool.
 }
 
-// Translate local snap coordinates into snap container's scrolling content
-// coordinate space.
-static Vector<FloatPoint> LocalToContainerSnapCoordinates(
-    const LayoutBox& container_box,
-    const LayoutBox& snap_area) {
-  Vector<FloatPoint> result;
-  LayoutPoint scroll_offset(container_box.ScrollLeft(),
-                            container_box.ScrollTop());
-
-  const Vector<LengthPoint>& snap_coordinates =
-      snap_area.Style()->ScrollSnapCoordinate();
-  for (auto& coordinate : snap_coordinates) {
-    FloatPoint local_point =
-        FloatPointForLengthPoint(coordinate, FloatSize(snap_area.Size()));
-    FloatPoint container_point =
-        snap_area.LocalToAncestorPoint(local_point, &container_box);
-    container_point.MoveBy(scroll_offset);
-    result.push_back(container_point);
-  }
-  return result;
-}
-
-Vector<double> SnapCoordinator::SnapOffsets(const ContainerNode& element,
-                                            ScrollbarOrientation orientation) {
-  const ComputedStyle* style = element.GetComputedStyle();
-  const LayoutBox* snap_container = element.GetLayoutBox();
-  DCHECK(style);
-  DCHECK(snap_container);
-
-  Vector<double> result;
-
-  if (style->GetScrollSnapType() == kScrollSnapTypeNone)
-    return result;
-
-  const ScrollSnapPoints& snap_points = (orientation == kHorizontalScrollbar)
-                                            ? style->ScrollSnapPointsX()
-                                            : style->ScrollSnapPointsY();
-
-  LayoutUnit client_size = (orientation == kHorizontalScrollbar)
-                               ? snap_container->ClientWidth()
-                               : snap_container->ClientHeight();
-  LayoutUnit scroll_size = (orientation == kHorizontalScrollbar)
-                               ? snap_container->ScrollWidth()
-                               : snap_container->ScrollHeight();
-
-  if (snap_points.has_repeat) {
-    LayoutUnit repeat = ValueForLength(snap_points.repeat_offset, client_size);
-
-    // calc() values may be negative or zero in which case we clamp them to 1px.
-    // See: https://lists.w3.org/Archives/Public/www-style/2015Jul/0075.html
-    repeat = std::max<LayoutUnit>(repeat, LayoutUnit(1));
-    for (LayoutUnit offset = repeat; offset <= (scroll_size - client_size);
-         offset += repeat) {
-      result.push_back(offset.ToFloat());
-    }
-  }
-
-  // Compute element-based snap points by mapping the snap coordinates from
-  // snap areas to snap container.
-  bool did_add_snap_area_offset = false;
-  if (SnapAreaSet* snap_areas = snap_container->SnapAreas()) {
-    for (auto& snap_area : *snap_areas) {
-      Vector<FloatPoint> snap_coordinates =
-          LocalToContainerSnapCoordinates(*snap_container, *snap_area);
-      for (const FloatPoint& snap_coordinate : snap_coordinates) {
-        float snap_offset = (orientation == kHorizontalScrollbar)
-                                ? snap_coordinate.X()
-                                : snap_coordinate.Y();
-        if (snap_offset > scroll_size - client_size)
-          continue;
-        result.push_back(snap_offset);
-        did_add_snap_area_offset = true;
-      }
-    }
-  }
-
-  if (did_add_snap_area_offset)
-    std::sort(result.begin(), result.end());
-
-  return result;
-}
-
 #ifndef NDEBUG
 
 void SnapCoordinator::ShowSnapAreaMap() {
   for (auto& container : snap_containers_)
     ShowSnapAreasFor(container);
 }
 
 void SnapCoordinator::ShowSnapAreasFor(const LayoutBox* container) {
   LOG(INFO) << *container->GetNode();
   if (SnapAreaSet* snap_areas = container->SnapAreas()) {
     for (auto& snap_area : *snap_areas) {
       LOG(INFO) << "    " << *snap_area->GetNode();
     }
   }
 }
 
 #endif
 
 }  // namespace blink