chromium/src/third_party/blink/renderer/core/paint/paint_layer_paint_order_iterator.cc

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 THE COPYRIGHT
 * OWNER 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,
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "third_party/blink/renderer/core/paint/paint_layer_paint_order_iterator.h"

#include "third_party/blink/renderer/core/paint/paint_layer.h"
#include "third_party/blink/renderer/core/paint/paint_layer_stacking_node.h"

namespace blink {

PaintLayer* PaintLayerPaintOrderIterator::Next() {
  if (remaining_children_ & kNegativeZOrderChildren) {
    if (root_.StackingNode()) {
      const auto& neg_z_order_list = root_.StackingNode()->NegZOrderList();
      if (index_ < neg_z_order_list.size())
        return neg_z_order_list[index_++];
    }

    index_ = 0;
    remaining_children_ &= ~kNegativeZOrderChildren;
  }

  if (remaining_children_ & kNormalFlowChildren) {
    for (; current_normal_flow_child_;
         current_normal_flow_child_ =
             current_normal_flow_child_->NextSibling()) {
      if (current_normal_flow_child_->GetLayoutObject().IsStacked())
        continue;

      PaintLayer* normal_flow_child = current_normal_flow_child_;
      current_normal_flow_child_ = current_normal_flow_child_->NextSibling();
      return normal_flow_child;
    }

    // We reset the iterator in case we reuse it.
    current_normal_flow_child_ = root_.FirstChild();
    remaining_children_ &= ~kNormalFlowChildren;
  }

  if (remaining_children_ & kPositiveZOrderChildren) {
    if (root_.StackingNode()) {
      const auto& pos_z_order_list = root_.StackingNode()->PosZOrderList();
      if (index_ < pos_z_order_list.size())
        return pos_z_order_list[index_++];
    }

    index_ = 0;
    remaining_children_ &= ~kPositiveZOrderChildren;
  }

  return nullptr;
}

PaintLayer* PaintLayerPaintOrderReverseIterator::Next() {
  if (remaining_children_ & kNegativeZOrderChildren) {
    if (root_.StackingNode()) {
      const auto& neg_z_order_list = root_.StackingNode()->NegZOrderList();
      if (index_ >= 0)
        return neg_z_order_list[index_--];
    }

    remaining_children_ &= ~kNegativeZOrderChildren;
    SetIndexToLastItem();
  }

  if (remaining_children_ & kNormalFlowChildren) {
    for (; current_normal_flow_child_;
         current_normal_flow_child_ =
             current_normal_flow_child_->PreviousSibling()) {
      if (current_normal_flow_child_->GetLayoutObject().IsStacked())
        continue;

      PaintLayer* normal_flow_child = current_normal_flow_child_;
      current_normal_flow_child_ =
          current_normal_flow_child_->PreviousSibling();
      return normal_flow_child;
    }

    remaining_children_ &= ~kNormalFlowChildren;
    SetIndexToLastItem();
  }

  if (remaining_children_ & kPositiveZOrderChildren) {
    if (root_.StackingNode()) {
      const auto& pos_z_order_list = root_.StackingNode()->PosZOrderList();
      if (index_ >= 0)
        return pos_z_order_list[index_--];
    }

    remaining_children_ &= ~kPositiveZOrderChildren;
    SetIndexToLastItem();
  }

  return nullptr;
}

void PaintLayerPaintOrderReverseIterator::SetIndexToLastItem() {
  if (remaining_children_ & kNegativeZOrderChildren) {
    if (root_.StackingNode()) {
      const auto& neg_z_order_list = root_.StackingNode()->NegZOrderList();
      if (!neg_z_order_list.IsEmpty()) {
        index_ = neg_z_order_list.size() - 1;
        return;
      }
    }

    remaining_children_ &= ~kNegativeZOrderChildren;
  }

  if (remaining_children_ & kNormalFlowChildren) {
    current_normal_flow_child_ = root_.LastChild();
    return;
  }

  if (remaining_children_ & kPositiveZOrderChildren) {
    if (root_.StackingNode()) {
      const auto& pos_z_order_list = root_.StackingNode()->PosZOrderList();
      if (!pos_z_order_list.IsEmpty()) {
        index_ = pos_z_order_list.size() - 1;
        return;
      }
    }

    remaining_children_ &= ~kPositiveZOrderChildren;
  }

  // No more list to visit.
  DCHECK(!remaining_children_);
  index_ = -1;
}

}  // namespace blink