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/*
* Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies)
* Copyright (C) 2009 Antonio Gomes <tonikitoo@webkit.org>
*
* All rights reserved.
*
* 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.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "third_party/blink/renderer/core/page/spatial_navigation.h"
#include "base/compiler_specific.h"
#include "base/containers/adapters.h"
#include "third_party/blink/public/mojom/scroll/scrollbar_mode.mojom-blink.h"
#include "third_party/blink/renderer/core/dom/node_traversal.h"
#include "third_party/blink/renderer/core/frame/local_frame.h"
#include "third_party/blink/renderer/core/frame/local_frame_view.h"
#include "third_party/blink/renderer/core/frame/settings.h"
#include "third_party/blink/renderer/core/frame/visual_viewport.h"
#include "third_party/blink/renderer/core/html/html_area_element.h"
#include "third_party/blink/renderer/core/html/html_frame_owner_element.h"
#include "third_party/blink/renderer/core/html/html_image_element.h"
#include "third_party/blink/renderer/core/html_names.h"
#include "third_party/blink/renderer/core/input/event_handler.h"
#include "third_party/blink/renderer/core/layout/layout_box.h"
#include "third_party/blink/renderer/core/layout/layout_inline.h"
#include "third_party/blink/renderer/core/layout/layout_view.h"
#include "third_party/blink/renderer/core/page/frame_tree.h"
#include "third_party/blink/renderer/core/page/page.h"
#include "third_party/blink/renderer/core/paint/paint_layer.h"
#include "third_party/blink/renderer/core/paint/paint_layer_scrollable_area.h"
#include "third_party/blink/renderer/platform/geometry/physical_offset.h"
#include "ui/gfx/geometry/rect.h"
namespace blink {
// A small integer that easily fits into a double with a good margin for
// arithmetic. In particular, we don't want to use
// std::numeric_limits<double>::lowest() because, if subtracted, it becomes
// NaN which will make all following arithmetic NaN too (an unusable number).
constexpr double kMinDistance = std::numeric_limits<int>::lowest();
// Assign negative values to the distance value to give the candidate a higher
// priority.
// kPriorityClassA is for elements in separate layers such as pop-ups.
// kPriorityClassB is for intersecting elements.
constexpr double kPriorityClassA = kMinDistance / 2;
constexpr double kPriorityClassB = kMinDistance / 4;
constexpr int kFudgeFactor = 2;
FocusCandidate::FocusCandidate(Node* node, SpatialNavigationDirection direction)
: visible_node(nullptr), focusable_node(nullptr), is_offscreen(true) {
DCHECK(node);
DCHECK(node->IsElementNode());
if (auto* area = DynamicTo<HTMLAreaElement>(*node)) {
HTMLImageElement* image = area->ImageElement();
if (!image || !image->GetLayoutObject())
return;
visible_node = image;
rect_in_root_frame = StartEdgeForAreaElement(*area, direction);
} else {
if (!node->GetLayoutObject())
return;
visible_node = node;
rect_in_root_frame = NodeRectInRootFrame(node);
// Remove any overlap with line boxes *above* the search origin.
rect_in_root_frame =
ShrinkInlineBoxToLineBox(*node->GetLayoutObject(), rect_in_root_frame);
}
focusable_node = node;
is_offscreen = IsOffscreen(visible_node);
}
bool IsSpatialNavigationEnabled(const LocalFrame* frame) {
return (frame && frame->GetSettings() &&
frame->GetSettings()->GetSpatialNavigationEnabled());
}
static bool RectsIntersectOnOrthogonalAxis(SpatialNavigationDirection direction,
const PhysicalRect& a,
const PhysicalRect& b) {
switch (direction) {
case SpatialNavigationDirection::kLeft:
case SpatialNavigationDirection::kRight:
return a.Bottom() > b.Y() && a.Y() < b.Bottom();
case SpatialNavigationDirection::kUp:
case SpatialNavigationDirection::kDown:
return a.Right() > b.X() && a.X() < b.Right();
default:
NOTREACHED();
}
}
// Determines if a candidate element is in a specific direction.
// It has to deal with overlapping situations.
// See https://github.com/w3c/csswg-drafts/issues/4483 for details.
// Return true if rect |a| is below |b|. False otherwise.
// For overlapping rects, |a| is considered to be below |b|,
// if the top edge of |a| is below the top edge of |b|.
static inline bool Below(const PhysicalRect& a, const PhysicalRect& b) {
return a.Y() >= b.Bottom() || (a.Y() > b.Y() && a.IntersectsInclusively(b));
}
// Return true if rect |a| is above |b|. False otherwise.
// For overlapping rects, |a| is considered to be above |b|,
// if the bottom edge of |a| is above the bottom edge of |b|.
static inline bool Above(const PhysicalRect& a, const PhysicalRect& b) {
return a.Bottom() <= b.Y() ||
(a.Bottom() < b.Bottom() && a.IntersectsInclusively(b));
}
// Return true if rect |a| is on the right of |b|. False otherwise.
// For overlapping rects, |a| is considered to be on the right of |b|,
// if the left edge of |a| is on the right of the left edge of |b|.
static inline bool RightOf(const PhysicalRect& a, const PhysicalRect& b) {
return a.X() >= b.Right() || (a.X() > b.X() && a.IntersectsInclusively(b));
}
// Return true if rect |a| is on the left of |b|. False otherwise.
// For overlapping rects, |a| is considered to be on the left of |b|,
// if the right edge of |a| is on the left of the right edge of |b|.
static inline bool LeftOf(const PhysicalRect& a, const PhysicalRect& b) {
return a.Right() <= b.X() ||
(a.Right() < b.Right() && a.IntersectsInclusively(b));
}
static bool IsRectInDirection(SpatialNavigationDirection direction,
const PhysicalRect& cur_rect,
const PhysicalRect& target_rect) {
if (target_rect.Contains(cur_rect)) {
// When leaving an "insider", don't focus its underlying container box.
// Go directly to the outside world. This avoids focus from being trapped
// inside a container.
return false;
} else if (cur_rect.Contains(target_rect)) {
// Treat "insider" as rect in direction
return true;
}
switch (direction) {
case SpatialNavigationDirection::kLeft:
return LeftOf(target_rect, cur_rect);
case SpatialNavigationDirection::kRight:
return RightOf(target_rect, cur_rect);
case SpatialNavigationDirection::kUp:
return Above(target_rect, cur_rect);
case SpatialNavigationDirection::kDown:
return Below(target_rect, cur_rect);
default:
NOTREACHED();
}
}
int LineBoxes(const LayoutObject& layout_object) {
if (!layout_object.IsInline() || layout_object.IsAtomicInlineLevel())
return 1;
// If it has empty quads, it's most likely not a line broken ("fragmented")
// text. <a><div></div></a> has for example one empty rect.
Vector<gfx::QuadF> quads;
layout_object.AbsoluteQuads(quads);
for (const gfx::QuadF& quad : quads) {
if (quad.BoundingBox().IsEmpty())
return 1;
}
return quads.size();
}
bool IsFragmentedInline(const LayoutObject& layout_object) {
return LineBoxes(layout_object) > 1;
}
gfx::RectF RectInViewport(const Node& node) {
LocalFrameView* frame_view = node.GetDocument().View();
if (!frame_view)
return gfx::RectF();
DCHECK(!frame_view->NeedsLayout());
LayoutObject* object = node.GetLayoutObject();
if (!object)
return gfx::RectF();
PhysicalRect rect_in_root_frame = NodeRectInRootFrame(&node);
// Convert to the visual viewport which will account for pinch zoom.
VisualViewport& visual_viewport =
object->GetDocument().GetPage()->GetVisualViewport();
gfx::RectF rect_in_viewport =
visual_viewport.RootFrameToViewport(gfx::RectF(rect_in_root_frame));
// RootFrameToViewport doesn't clip so manually apply the viewport clip here.
gfx::RectF viewport_rect(gfx::SizeF(visual_viewport.Size()));
rect_in_viewport.Intersect(viewport_rect);
return rect_in_viewport;
}
// Answers true if |node| is completely outside the user's (visual) viewport.
// This logic is used by spatnav to rule out offscreen focus candidates and an
// offscreen activeElement. When activeElement is offscreen, spatnav doesn't use
// it as the search origin; the search will start at an edge of the visual
// viewport instead.
// TODO(crbug.com/889840): Fix VisibleBoundsInVisualViewport().
// If VisibleBoundsInVisualViewport() would have taken "element-clips" into
// account, spatnav could have called it directly; no need to check the
// LayoutObject's VisibleContentRect.
bool IsOffscreen(const Node* node) {
DCHECK(node);
return RectInViewport(*node).IsEmpty();
}
ScrollableArea* ScrollableAreaFor(const Node* node) {
if (node->IsDocumentNode()) {
LocalFrameView* view = node->GetDocument().View();
if (!view)
return nullptr;
return view->GetScrollableArea();
}
LayoutObject* object = node->GetLayoutObject();
if (!object || !object->IsBox())
return nullptr;
return To<LayoutBox>(object)->GetScrollableArea();
}
bool IsUnobscured(const FocusCandidate& candidate) {
DCHECK(candidate.visible_node);
const LocalFrame* local_main_frame = DynamicTo<LocalFrame>(
candidate.visible_node->GetDocument().GetPage()->MainFrame());
if (!local_main_frame)
return false;
PhysicalRect viewport_rect(
local_main_frame->GetPage()->GetVisualViewport().VisibleContentRect());
PhysicalRect interesting_rect =
Intersection(candidate.rect_in_root_frame, viewport_rect);
if (interesting_rect.IsEmpty())
return false;
HitTestLocation location(interesting_rect);
HitTestResult result =
local_main_frame->GetEventHandler().HitTestResultAtLocation(
location, HitTestRequest::kReadOnly | HitTestRequest::kListBased |
HitTestRequest::kIgnoreZeroOpacityObjects |
HitTestRequest::kAllowChildFrameContent);
const HitTestResult::NodeSet& nodes = result.ListBasedTestResult();
for (const auto& hit_node : base::Reversed(nodes)) {
if (candidate.visible_node->ContainsIncludingHostElements(*hit_node))
return true;
if (FrameOwnerElement(candidate) &&
FrameOwnerElement(candidate)
->contentDocument()
->ContainsIncludingHostElements(*hit_node))
return true;
}
return false;
}
bool HasRemoteFrame(const Node* node) {
auto* frame_owner_element = DynamicTo<HTMLFrameOwnerElement>(node);
if (!frame_owner_element)
return false;
return frame_owner_element->ContentFrame() &&
frame_owner_element->ContentFrame()->IsRemoteFrame();
}
bool ScrollInDirection(Node* container, SpatialNavigationDirection direction) {
DCHECK(container);
if (!CanScrollInDirection(container, direction))
return false;
int dx = 0;
int dy = 0;
int pixels_per_line_step =
ScrollableArea::PixelsPerLineStep(container->GetDocument().GetFrame());
switch (direction) {
case SpatialNavigationDirection::kLeft:
dx = -pixels_per_line_step;
break;
case SpatialNavigationDirection::kRight:
// TODO(bokan, https://crbug.com/952326): Fix this DCHECK.
// DCHECK_GT(container->GetLayoutBox()->ScrollWidth(),
// container->GetLayoutBoxForScrolling()
// ->GetScrollableArea()
// ->ScrollPosition()
// .X() +
// container->GetLayoutBox()->ClientWidth());
dx = pixels_per_line_step;
break;
case SpatialNavigationDirection::kUp:
dy = -pixels_per_line_step;
break;
case SpatialNavigationDirection::kDown:
// TODO(bokan, https://crbug.com/952326): Fix this DCHECK.
// DCHECK_GT(container->GetLayoutBox()->ScrollHeight(),
// container->GetLayoutBoxForScrolling()
// ->GetScrollableArea()
// ->ScrollPosition()
// .Y() +
// container->GetLayoutBox()->ClientHeight());
dy = pixels_per_line_step;
break;
default:
NOTREACHED();
}
// TODO(crbug.com/914775): Use UserScroll() instead. UserScroll() does a
// smooth, animated scroll which might make it easier for users to understand
// spatnav's moves. Another advantage of using ScrollableArea::UserScroll() is
// that it returns a ScrollResult so we don't need to call
// CanScrollInDirection(). Regular arrow-key scrolling (without
// --enable-spatial-navigation) already uses smooth scrolling by default.
ScrollableArea* scroller = ScrollableAreaFor(container);
if (!scroller)
return false;
scroller->ScrollBy(ScrollOffset(dx, dy), mojom::blink::ScrollType::kUser);
return true;
}
bool IsScrollableNode(const Node* node) {
if (!node)
return false;
if (node->IsDocumentNode())
return true;
if (auto* box = DynamicTo<LayoutBox>(node->GetLayoutObject())) {
return box->IsUserScrollable();
}
return false;
}
Node* ScrollableAreaOrDocumentOf(Node* node) {
DCHECK(node);
Node* parent = node;
do {
// FIXME: Spatial navigation is broken for OOPI.
if (auto* document = DynamicTo<Document>(parent))
parent = document->GetFrame()->DeprecatedLocalOwner();
else
parent = parent->ParentOrShadowHostNode();
} while (parent && !IsScrollableAreaOrDocument(parent));
return parent;
}
bool IsScrollableAreaOrDocument(const Node* node) {
if (!node)
return false;
auto* frame_owner_element = DynamicTo<HTMLFrameOwnerElement>(node);
return (frame_owner_element && frame_owner_element->ContentFrame()) ||
IsScrollableNode(node);
}
bool CanScrollInDirection(const Node* container,
SpatialNavigationDirection direction) {
DCHECK(container);
if (auto* document = DynamicTo<Document>(container))
return CanScrollInDirection(document->GetFrame(), direction);
if (!IsScrollableNode(container))
return false;
const Element* container_element = DynamicTo<Element>(container);
if (!container_element)
return false;
LayoutBox* box = container_element->GetLayoutBoxForScrolling();
if (!box)
return false;
auto* scrollable_area = box->GetScrollableArea();
if (!scrollable_area)
return false;
DCHECK(container->GetLayoutObject());
switch (direction) {
case SpatialNavigationDirection::kLeft:
return (container->GetLayoutObject()->Style()->OverflowX() !=
EOverflow::kHidden &&
scrollable_area->GetScrollOffset().x() >
scrollable_area->MinimumScrollOffset().x());
case SpatialNavigationDirection::kUp:
return (container->GetLayoutObject()->Style()->OverflowY() !=
EOverflow::kHidden &&
scrollable_area->GetScrollOffset().y() >
scrollable_area->MinimumScrollOffset().y());
case SpatialNavigationDirection::kRight:
return (container->GetLayoutObject()->Style()->OverflowX() !=
EOverflow::kHidden &&
scrollable_area->GetScrollOffset().x() <
scrollable_area->MaximumScrollOffset().x());
case SpatialNavigationDirection::kDown:
return (container->GetLayoutObject()->Style()->OverflowY() !=
EOverflow::kHidden &&
scrollable_area->GetScrollOffset().y() <
scrollable_area->MaximumScrollOffset().y());
default:
NOTREACHED();
}
}
bool CanScrollInDirection(const LocalFrame* frame,
SpatialNavigationDirection direction) {
if (!frame->View())
return false;
LayoutView* layoutView = frame->ContentLayoutObject();
if (!layoutView)
return false;
mojom::blink::ScrollbarMode vertical_mode;
mojom::blink::ScrollbarMode horizontal_mode;
layoutView->CalculateScrollbarModes(horizontal_mode, vertical_mode);
if ((direction == SpatialNavigationDirection::kLeft ||
direction == SpatialNavigationDirection::kRight) &&
mojom::blink::ScrollbarMode::kAlwaysOff == horizontal_mode)
return false;
if ((direction == SpatialNavigationDirection::kUp ||
direction == SpatialNavigationDirection::kDown) &&
mojom::blink::ScrollbarMode::kAlwaysOff == vertical_mode)
return false;
ScrollableArea* scrollable_area = frame->View()->GetScrollableArea();
gfx::Size size = scrollable_area->ContentsSize();
gfx::Vector2d offset = scrollable_area->ScrollOffsetInt();
PhysicalRect rect(scrollable_area->VisibleContentRect(kIncludeScrollbars));
switch (direction) {
case SpatialNavigationDirection::kLeft:
return offset.x() > 0;
case SpatialNavigationDirection::kUp:
return offset.y() > 0;
case SpatialNavigationDirection::kRight:
return rect.Width() + offset.x() < size.width();
case SpatialNavigationDirection::kDown:
return rect.Height() + offset.y() < size.height();
default:
NOTREACHED();
}
}
PhysicalRect NodeRectInRootFrame(const Node* node) {
DCHECK(node);
DCHECK(node->GetLayoutObject());
DCHECK(!node->GetDocument().View()->NeedsLayout());
LayoutObject* object = node->GetLayoutObject();
PhysicalRect rect = PhysicalRect::EnclosingRect(
object->LocalBoundingBoxRectForAccessibility());
// Inset the bounding box by the border.
// TODO(bokan): As far as I can tell, this is to work around empty iframes
// that have a border. It's unclear if that's still useful.
rect.ContractEdges(LayoutUnit(object->StyleRef().BorderTopWidth()),
LayoutUnit(object->StyleRef().BorderRightWidth()),
LayoutUnit(object->StyleRef().BorderBottomWidth()),
LayoutUnit(object->StyleRef().BorderLeftWidth()));
object->MapToVisualRectInAncestorSpace(/*ancestor=*/nullptr, rect);
return rect;
}
// This method calculates the exit_point from the starting_rect and the
// entry_point into the candidate rect, and returns a pair of the entry_point
// and the exit_point. The line between those 2 points is the closest
// distance between the 2 rects. Takes care of overlapping rects, defining
// points so that the distance between them is zero where necessary.
std::pair<PhysicalOffset, PhysicalOffset> EntryAndExitPointsForDirection(
SpatialNavigationDirection direction,
const PhysicalRect& starting_rect,
const PhysicalRect& potential_rect) {
PhysicalOffset exit_point;
PhysicalOffset entry_point;
switch (direction) {
case SpatialNavigationDirection::kLeft:
exit_point.left = starting_rect.X();
entry_point.left = std::min(potential_rect.Right(), starting_rect.X());
break;
case SpatialNavigationDirection::kUp:
exit_point.top = starting_rect.Y();
entry_point.top = std::min(potential_rect.Bottom(), starting_rect.Y());
break;
case SpatialNavigationDirection::kRight:
exit_point.left = starting_rect.Right();
entry_point.left = std::max(potential_rect.X(), starting_rect.Right());
break;
case SpatialNavigationDirection::kDown:
exit_point.top = starting_rect.Bottom();
entry_point.top = std::max(potential_rect.Y(), starting_rect.Bottom());
break;
default:
NOTREACHED();
}
switch (direction) {
case SpatialNavigationDirection::kLeft:
case SpatialNavigationDirection::kRight:
if (Below(starting_rect, potential_rect)) {
exit_point.top = starting_rect.Y();
entry_point.top = std::min(potential_rect.Bottom(), starting_rect.Y());
} else if (Below(potential_rect, starting_rect)) {
exit_point.top = starting_rect.Bottom();
entry_point.top = std::max(potential_rect.Y(), starting_rect.Bottom());
} else {
exit_point.top = std::max(starting_rect.Y(), potential_rect.Y());
entry_point.top = exit_point.top;
}
break;
case SpatialNavigationDirection::kUp:
case SpatialNavigationDirection::kDown:
if (RightOf(starting_rect, potential_rect)) {
exit_point.left = starting_rect.X();
entry_point.left = std::min(potential_rect.Right(), starting_rect.X());
} else if (RightOf(potential_rect, starting_rect)) {
exit_point.left = starting_rect.Right();
entry_point.left = std::max(potential_rect.X(), starting_rect.Right());
} else {
exit_point.left = std::max(starting_rect.X(), potential_rect.X());
entry_point.left = exit_point.left;
}
break;
default:
NOTREACHED();
}
return {entry_point, exit_point};
}
double ProjectedOverlap(SpatialNavigationDirection direction,
PhysicalRect current,
PhysicalRect candidate) {
switch (direction) {
case SpatialNavigationDirection::kLeft:
case SpatialNavigationDirection::kRight:
current.SetWidth(LayoutUnit(1));
candidate.SetX(current.X());
current.Intersect(candidate);
return current.Height();
case SpatialNavigationDirection::kUp:
case SpatialNavigationDirection::kDown:
current.SetHeight(LayoutUnit(1));
candidate.SetY(current.Y());
current.Intersect(candidate);
return current.Width();
default:
NOTREACHED();
}
}
double Alignment(SpatialNavigationDirection direction,
PhysicalRect current,
PhysicalRect candidate) {
// The formula and constants for "alignment" are experimental and
// come from https://drafts.csswg.org/css-nav-1/#heuristics.
const int kAlignWeight = 5;
double projected_overlap = ProjectedOverlap(direction, current, candidate);
switch (direction) {
case SpatialNavigationDirection::kLeft:
case SpatialNavigationDirection::kRight:
return (kAlignWeight * projected_overlap) / current.Height();
case SpatialNavigationDirection::kUp:
case SpatialNavigationDirection::kDown:
return (kAlignWeight * projected_overlap) / current.Width();
default:
NOTREACHED();
}
}
bool BothOnTopmostPaintLayerInStackingContext(
const FocusCandidate& current_interest,
const FocusCandidate& candidate) {
if (!current_interest.visible_node)
return false;
const LayoutObject* origin = current_interest.visible_node->GetLayoutObject();
const PaintLayer* focused_layer = origin->PaintingLayer();
if (!focused_layer || focused_layer->IsRootLayer())
return false;
const LayoutObject* next = candidate.visible_node->GetLayoutObject();
const PaintLayer* candidate_layer = next->PaintingLayer();
if (focused_layer != candidate_layer)
return false;
return !candidate_layer->HasVisibleSelfPaintingDescendant();
}
double ComputeDistanceDataForNode(SpatialNavigationDirection direction,
const FocusCandidate& current_interest,
const FocusCandidate& candidate) {
double distance = 0.0;
PhysicalRect node_rect = candidate.rect_in_root_frame;
PhysicalRect current_rect = current_interest.rect_in_root_frame;
if (!IsRectInDirection(direction, current_rect, node_rect)) {
return kMaxDistance;
}
if (BothOnTopmostPaintLayerInStackingContext(current_interest, candidate)) {
// Prioritize "popup candidates" over other candidates by giving them a
// negative, < 0, distance number.
distance = kPriorityClassA;
} else if (current_rect.IntersectsInclusively(node_rect)) {
// We prioritize intersecting candidates, candidates that overlap
// the current focus rect, by giving them a negative, < 0, distance
// number. https://drafts.csswg.org/css-nav-1/#select-the-best-candidate
distance = kPriorityClassB;
// For intersecting candidates we cannot measure the distance from the
// outer box. Instead, we measure distance _from_ the focused container's
// rect's "opposite edge" in the navigated direction, just like we do when
// we look for candidates inside a focused scroll container.
current_rect = OppositeEdge(direction, current_rect);
// This candidate overlaps the current focus rect so we can omit the
// overlap term of the equation. An "intersecting candidate" will always
// win against an "outsider".
}
const auto [entry_point, exit_point] =
EntryAndExitPointsForDirection(direction, current_rect, node_rect);
LayoutUnit x_axis = (exit_point.left - entry_point.left).Abs();
LayoutUnit y_axis = (exit_point.top - entry_point.top).Abs();
double euclidian_distance =
sqrt((x_axis * x_axis + y_axis * y_axis).ToDouble());
distance += euclidian_distance;
LayoutUnit navigation_axis_distance;
LayoutUnit weighted_orthogonal_axis_distance;
// Bias and weights are put to the orthogonal axis distance calculation
// so aligned candidates would have advantage over partially-aligned ones
// and then over not-aligned candidates. The bias is given to not-aligned
// candidates with respect to size of the current rect. The weight for
// left/right direction is given a higher value to allow navigation on
// common horizonally-aligned elements. The hardcoded values are based on
// tests and experiments.
const int kOrthogonalWeightForLeftRight = 30;
const int kOrthogonalWeightForUpDown = 2;
int orthogonal_bias = 0;
switch (direction) {
case SpatialNavigationDirection::kLeft:
case SpatialNavigationDirection::kRight:
navigation_axis_distance = x_axis;
if (!RectsIntersectOnOrthogonalAxis(direction, current_rect, node_rect))
orthogonal_bias = (current_rect.Height() / 2).ToInt();
weighted_orthogonal_axis_distance =
(y_axis + orthogonal_bias) * kOrthogonalWeightForLeftRight;
break;
case SpatialNavigationDirection::kUp:
case SpatialNavigationDirection::kDown:
navigation_axis_distance = y_axis;
if (!RectsIntersectOnOrthogonalAxis(direction, current_rect, node_rect))
orthogonal_bias = (current_rect.Width() / 2).ToInt();
weighted_orthogonal_axis_distance =
(x_axis + orthogonal_bias) * kOrthogonalWeightForUpDown;
break;
default:
NOTREACHED();
}
// We try to formalize this distance calculation at
// https://drafts.csswg.org/css-nav-1/.
distance += weighted_orthogonal_axis_distance.ToDouble() +
navigation_axis_distance.ToDouble();
return distance - Alignment(direction, current_rect, node_rect);
}
// Returns a thin rectangle that represents one of |box|'s edges.
// To not intersect elements that are positioned inside |box|, we add one
// LayoutUnit of margin that puts the returned slice "just outside" |box|.
PhysicalRect OppositeEdge(SpatialNavigationDirection side,
const PhysicalRect& box,
LayoutUnit thickness) {
PhysicalRect thin_rect = box;
switch (side) {
case SpatialNavigationDirection::kLeft:
thin_rect.SetX(thin_rect.Right() - thickness);
thin_rect.SetWidth(thickness);
thin_rect.offset.left += 1;
break;
case SpatialNavigationDirection::kRight:
thin_rect.SetWidth(thickness);
thin_rect.offset.left -= 1;
break;
case SpatialNavigationDirection::kDown:
thin_rect.SetHeight(thickness);
thin_rect.offset.top -= 1;
break;
case SpatialNavigationDirection::kUp:
thin_rect.SetY(thin_rect.Bottom() - thickness);
thin_rect.SetHeight(thickness);
thin_rect.offset.top += 1;
break;
default:
NOTREACHED();
}
return thin_rect;
}
PhysicalRect StartEdgeForAreaElement(const HTMLAreaElement& area,
SpatialNavigationDirection direction) {
DCHECK(area.ImageElement());
// Area elements tend to overlap more than other focusable elements. We
// flatten the rect of the area elements to minimize the effect of overlapping
// areas.
PhysicalRect rect = OppositeEdge(
direction,
area.GetDocument().GetFrame()->View()->ConvertToRootFrame(
area.ComputeAbsoluteRect(area.ImageElement()->GetLayoutObject())),
LayoutUnit(kFudgeFactor) /* snav-imagemap-overlapped-areas.html */);
return rect;
}
HTMLFrameOwnerElement* FrameOwnerElement(const FocusCandidate& candidate) {
return DynamicTo<HTMLFrameOwnerElement>(candidate.visible_node);
}
// The visual viewport's rect (given in the root frame's coordinate space).
PhysicalRect RootViewport(const LocalFrame* current_frame) {
return PhysicalRect::EnclosingRect(
current_frame->GetPage()->GetVisualViewport().VisibleRect());
}
// Ignores fragments that are completely offscreen.
// Returns the first one that is not offscreen, in the given iterator range.
template <class Iterator>
PhysicalRect FirstVisibleFragment(const PhysicalRect& visibility,
Iterator fragment,
Iterator end) {
while (fragment != end) {
PhysicalRect physical_fragment =
PhysicalRect::EnclosingRect(fragment->BoundingBox());
physical_fragment.Intersect(visibility);
if (!physical_fragment.IsEmpty())
return physical_fragment;
UNSAFE_TODO(++fragment);
}
return visibility;
}
LayoutUnit GetLogicalHeight(const PhysicalRect& rect,
const LayoutObject& layout_object) {
if (layout_object.IsHorizontalWritingMode())
return rect.Height();
else
return rect.Width();
}
void SetLogicalHeight(PhysicalRect& rect,
const LayoutObject& layout_object,
LayoutUnit height) {
if (layout_object.IsHorizontalWritingMode())
rect.SetHeight(height);
else
rect.SetWidth(height);
}
LayoutUnit TallestInlineAtomicChild(const LayoutObject& layout_object) {
LayoutUnit max_child_size(0);
if (!layout_object.IsLayoutInline())
return max_child_size;
for (LayoutObject* child = layout_object.SlowFirstChild(); child;
child = child->NextSibling()) {
if (child->IsOutOfFlowPositioned())
continue;
if (child->IsAtomicInlineLevel()) {
max_child_size =
std::max(To<LayoutBox>(child)->LogicalHeight(), max_child_size);
}
}
return max_child_size;
}
// "Although margins, borders, and padding of non-replaced elements do not
// enter into the line box calculation, they are still rendered around
// inline boxes. This means that if the height specified by line-height is
// less than the content height of contained boxes, backgrounds and colors
// of padding and borders may "bleed" into adjoining line boxes". [1]
// [1] https://drafts.csswg.org/css2/#leading
// [2] https://drafts.csswg.org/css2/#line-box
// [3] https://drafts.csswg.org/css2/#atomic-inline-level-boxes
//
// If an inline box is "bleeding", ShrinkInlineBoxToLineBox shrinks its
// rect to the size of of its "line box" [2]. We need to do so because
// "bleeding" can make links intersect vertically. We need to avoid that
// overlap because it could make links on the same line (to the left or right)
// unreachable as SpatNav's distance formula favors intersecting rects (on the
// line below or above).
PhysicalRect ShrinkInlineBoxToLineBox(const LayoutObject& layout_object,
PhysicalRect node_rect,
int line_boxes) {
if (!layout_object.IsInline() || layout_object.IsLayoutReplaced() ||
layout_object.IsButtonOrInputButton()) {
return node_rect;
}
// If actual line-height is bigger than the inline box, we shouldn't change
// anything. This is, for example, needed to not break
// snav-stay-in-overflow-div.html where the link's inline box doesn't fill
// the entire line box vertically.
LayoutUnit line_height = layout_object.StyleRef().ComputedLineHeightAsFixed();
LayoutUnit current_height = GetLogicalHeight(node_rect, layout_object);
if (line_height >= current_height)
return node_rect;
// Handle focusables like <a><img><a> (a LayoutInline that carries atomic
// inline boxes [3]). Despite a small line-height on the <a>, <a>'s line box
// will still fit the <img>.
line_height = std::max(TallestInlineAtomicChild(layout_object), line_height);
if (line_height >= current_height)
return node_rect;
// Cap the box at its line height to avoid overlapping inline links.
// Links can overlap vertically when CSS line-height < font-size, see
// snav-line-height_less_font-size.html.
line_boxes = line_boxes == -1 ? LineBoxes(layout_object) : line_boxes;
line_height = line_height * line_boxes;
if (line_height >= current_height)
return node_rect;
SetLogicalHeight(node_rect, layout_object, line_height);
return node_rect;
}
// TODO(crbug.com/1131419): Add tests and support for other writing-modes.
PhysicalRect SearchOriginFragment(const PhysicalRect& visible_part,
const LayoutObject& fragmented,
const SpatialNavigationDirection direction) {
// For accuracy, use the first visible fragment (not the fragmented element's
// entire bounding rect which is a union of all fragments) as search origin.
Vector<gfx::QuadF> fragments;
fragmented.AbsoluteQuads(
fragments, kTraverseDocumentBoundaries | kApplyRemoteMainFrameTransform);
switch (direction) {
case SpatialNavigationDirection::kLeft:
case SpatialNavigationDirection::kDown:
// Search from the topmost fragment.
return FirstVisibleFragment(visible_part, fragments.begin(),
fragments.end());
case SpatialNavigationDirection::kRight:
case SpatialNavigationDirection::kUp:
// Search from the bottommost fragment.
return FirstVisibleFragment(visible_part, fragments.rbegin(),
fragments.rend());
case SpatialNavigationDirection::kNone:
break;
// Nothing to do.
}
return visible_part;
}
// Spatnav uses this rectangle to measure distances to focus candidates.
// The search origin is either activeElement F itself, if it's being at least
// partially visible, or else, its first [partially] visible scroller. If both
// F and its enclosing scroller are completely off-screen, we recurse to the
// scroller’s scroller ... all the way up until the root frame's document.
// The root frame's document is a good base case because it's, per definition,
// a visible scrollable area.
PhysicalRect SearchOrigin(const PhysicalRect& viewport_rect_of_root_frame,
Node* focus_node,
const SpatialNavigationDirection direction) {
if (!focus_node) {
// Search from one of the visual viewport's edges towards the navigated
// direction. For example, UP makes spatnav search upwards, starting at the
// visual viewport's bottom.
return OppositeEdge(direction, viewport_rect_of_root_frame);
}
auto* area_element = DynamicTo<HTMLAreaElement>(focus_node);
if (area_element)
focus_node = area_element->ImageElement();
if (!IsOffscreen(focus_node)) {
if (area_element)
return StartEdgeForAreaElement(*area_element, direction);
PhysicalRect box_in_root_frame = NodeRectInRootFrame(focus_node);
PhysicalRect visible_part =
Intersection(box_in_root_frame, viewport_rect_of_root_frame);
const LayoutObject* const layout_object = focus_node->GetLayoutObject();
if (IsFragmentedInline(*layout_object)) {
visible_part =
SearchOriginFragment(visible_part, *layout_object, direction);
}
// Remove any overlap with line boxes *below* the search origin.
// The search origin is always only one line (because if |focus_node| is
// line broken, SearchOriginFragment picks the first or last line's box).
visible_part = ShrinkInlineBoxToLineBox(*layout_object, visible_part, 1);
return visible_part;
}
Node* container = ScrollableAreaOrDocumentOf(focus_node);
while (container) {
if (!IsOffscreen(container)) {
// The first scroller that encloses focus and is [partially] visible.
PhysicalRect box_in_root_frame = NodeRectInRootFrame(container);
return OppositeEdge(direction, Intersection(box_in_root_frame,
viewport_rect_of_root_frame));
}
container = ScrollableAreaOrDocumentOf(container);
}
return OppositeEdge(direction, viewport_rect_of_root_frame);
}
} // namespace blink
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