third_party/WebKit/Source/core/page/SpatialNavigation.h

/*
 * Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies)
 * Copyright (C) 2009 Antonio Gomes <tonikitoo@webkit.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#ifndef SpatialNavigation_h
#define SpatialNavigation_h

#include "core/dom/Node.h"
#include "platform/geometry/LayoutRect.h"
#include "public/platform/WebFocusType.h"

#include <limits>

namespace blink {

class LocalFrame;
class HTMLAreaElement;
class HTMLFrameOwnerElement;

inline double maxDistance() {
  return std::numeric_limits<double>::max();
}

inline int fudgeFactor() {
  return 2;
}

bool isSpatialNavigationEnabled(const LocalFrame*);
bool spatialNavigationIgnoresEventHandlers(const LocalFrame*);

// Spatially speaking, two given elements in a web page can be:
// 1) Fully aligned: There is a full intersection between the rects, either
//    vertically or horizontally.
//
// * Horizontally       * Vertically
//    _
//   |_|                   _ _ _ _ _ _
//   |_|...... _          |_|_|_|_|_|_|
//   |_|      |_|         .       .
//   |_|......|_|   OR    .       .
//   |_|      |_|         .       .
//   |_|......|_|          _ _ _ _
//   |_|                  |_|_|_|_|
//
//
// 2) Partially aligned: There is a partial intersection between the rects,
//    either vertically or horizontally.
//
// * Horizontally       * Vertically
//    _                   _ _ _ _ _
//   |_|                 |_|_|_|_|_|
//   |_|.... _      OR           . .
//   |_|    |_|                  . .
//   |_|....|_|                  ._._ _
//          |_|                  |_|_|_|
//          |_|
//
// 3) Or, otherwise, not aligned at all.
//
// * Horizontally       * Vertically
//         _              _ _ _ _
//        |_|            |_|_|_|_|
//        |_|                    .
//        |_|                     .
//       .          OR             .
//    _ .                           ._ _ _ _ _
//   |_|                            |_|_|_|_|_|
//   |_|
//   |_|
//
// "Totally Aligned" elements are preferable candidates to move
// focus to over "Partially Aligned" ones, that on its turns are
// more preferable than "Not Aligned".
enum RectsAlignment { None = 0, Partial, Full };

struct FocusCandidate {
  STACK_ALLOCATED();

 public:
  FocusCandidate()
      : visibleNode(nullptr),
        focusableNode(nullptr),
        enclosingScrollableBox(nullptr),
        distance(maxDistance()),
        isOffscreen(true),
        isOffscreenAfterScrolling(true) {}

  FocusCandidate(Node*, WebFocusType);
  explicit FocusCandidate(HTMLAreaElement*, WebFocusType);
  bool isNull() const { return !visibleNode; }
  bool inScrollableContainer() const {
    return visibleNode && enclosingScrollableBox;
  }
  bool isFrameOwnerElement() const {
    return visibleNode && visibleNode->isFrameOwnerElement();
  }
  Document* document() const {
    return visibleNode ? &visibleNode->document() : nullptr;
  }

  // We handle differently visibleNode and FocusableNode to properly handle the
  // areas of imagemaps, where visibleNode would represent the image element and
  // focusableNode would represent the area element.  In all other cases,
  // visibleNode and focusableNode are one and the same.
  Member<Node> visibleNode;
  Member<Node> focusableNode;
  Member<Node> enclosingScrollableBox;
  double distance;
  LayoutRect rect;
  bool isOffscreen;
  bool isOffscreenAfterScrolling;
};

bool hasOffscreenRect(Node*, WebFocusType = WebFocusTypeNone);
bool scrollInDirection(LocalFrame*, WebFocusType);
bool scrollInDirection(Node* container, WebFocusType);
bool canScrollInDirection(const Node* container, WebFocusType);
bool canScrollInDirection(const LocalFrame*, WebFocusType);
bool canBeScrolledIntoView(WebFocusType, const FocusCandidate&);
bool areElementsOnSameLine(const FocusCandidate& firstCandidate,
                           const FocusCandidate& secondCandidate);
void distanceDataForNode(WebFocusType,
                         const FocusCandidate& current,
                         FocusCandidate&);
Node* scrollableEnclosingBoxOrParentFrameForNodeInDirection(WebFocusType,
                                                            Node*);
LayoutRect nodeRectInAbsoluteCoordinates(Node*, bool ignoreBorder = false);
LayoutRect frameRectInAbsoluteCoordinates(LocalFrame*);
LayoutRect virtualRectForDirection(WebFocusType,
                                   const LayoutRect& startingRect,
                                   LayoutUnit width = LayoutUnit());
LayoutRect virtualRectForAreaElementAndDirection(HTMLAreaElement&,
                                                 WebFocusType);
HTMLFrameOwnerElement* frameOwnerElement(FocusCandidate&);

}  // namespace blink

#endif  // SpatialNavigation_h