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++ // Copyright (C) 2016 The Qt Company Ltd.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
++
++ #include "areaallocator_p.h"
++
++ #include <QtCore/qglobal.h>
++ #include <QtCore/qrect.h>
++ #include <QtCore/qpoint.h>
++
++ //
++ // This file is copied from qtdeclarative/src/quick/scenegraph/util/qsgareaallocator.cpp
++ //
++
++ QT_BEGIN_NAMESPACE
++
++ namespace Qt3DExtras {
++
++ enum SplitType
++ {
++ VerticalSplit,
++ HorizontalSplit
++ };
++
++ static const int maxMargin = 2;
++
++ struct AreaAllocatorNode
++ {
++ AreaAllocatorNode(AreaAllocatorNode *parent);
++ ~AreaAllocatorNode();
++ inline bool isLeaf();
++
++ AreaAllocatorNode *parent;
++ AreaAllocatorNode *left;
++ AreaAllocatorNode *right;
++ int split; // only valid for inner nodes.
++ SplitType splitType;
++ bool isOccupied; // only valid for leaf nodes.
++ };
++
++ AreaAllocatorNode::AreaAllocatorNode(AreaAllocatorNode *parent)
++ : parent(parent)
++ , left(0)
++ , right(0)
++ , isOccupied(false)
++ {
++ }
++
++ AreaAllocatorNode::~AreaAllocatorNode()
++ {
++ delete left;
++ delete right;
++ }
++
++ bool AreaAllocatorNode::isLeaf()
++ {
++ Q_ASSERT((left != 0) == (right != 0));
++ return !left;
++ }
++
++
++ AreaAllocator::AreaAllocator(const QSize &size) : m_size(size)
++ {
++ m_root = new AreaAllocatorNode(0);
++ }
++
++ AreaAllocator::~AreaAllocator()
++ {
++ delete m_root;
++ }
++
++ QRect AreaAllocator::allocate(const QSize &size)
++ {
++ QPoint point;
++ bool result = allocateInNode(size, point, QRect(QPoint(0, 0), m_size), m_root);
++ return result ? QRect(point, size) : QRect();
++ }
++
++ bool AreaAllocator::deallocate(const QRect &rect)
++ {
++ return deallocateInNode(rect.topLeft(), m_root);
++ }
++
++ bool AreaAllocator::allocateInNode(const QSize &size, QPoint &result, const QRect ¤tRect, AreaAllocatorNode *node)
++ {
++ if (size.width() > currentRect.width() || size.height() > currentRect.height())
++ return false;
++
++ if (node->isLeaf()) {
++ if (node->isOccupied)
++ return false;
++ if (size.width() + maxMargin >= currentRect.width() && size.height() + maxMargin >= currentRect.height()) {
++ //Snug fit, occupy entire rectangle.
++ node->isOccupied = true;
++ result = currentRect.topLeft();
++ return true;
++ }
++ // TODO: Reuse nodes.
++ // Split node.
++ node->left = new AreaAllocatorNode(node);
++ node->right = new AreaAllocatorNode(node);
++ QRect splitRect = currentRect;
++ if ((currentRect.width() - size.width()) * currentRect.height() < (currentRect.height() - size.height()) * currentRect.width()) {
++ node->splitType = HorizontalSplit;
++ node->split = currentRect.top() + size.height();
++ splitRect.setHeight(size.height());
++ } else {
++ node->splitType = VerticalSplit;
++ node->split = currentRect.left() + size.width();
++ splitRect.setWidth(size.width());
++ }
++ return allocateInNode(size, result, splitRect, node->left);
++ } else {
++ // TODO: avoid unnecessary recursion.
++ // has been split.
++ QRect leftRect = currentRect;
++ QRect rightRect = currentRect;
++ if (node->splitType == HorizontalSplit) {
++ leftRect.setHeight(node->split - leftRect.top());
++ rightRect.setTop(node->split);
++ } else {
++ leftRect.setWidth(node->split - leftRect.left());
++ rightRect.setLeft(node->split);
++ }
++ if (allocateInNode(size, result, leftRect, node->left))
++ return true;
++ if (allocateInNode(size, result, rightRect, node->right))
++ return true;
++ return false;
++ }
++ }
++
++ bool AreaAllocator::deallocateInNode(const QPoint &pos, AreaAllocatorNode *node)
++ {
++ while (!node->isLeaf()) {
++ // has been split.
++ int cmp = node->splitType == HorizontalSplit ? pos.y() : pos.x();
++ node = cmp < node->split ? node->left : node->right;
++ }
++ if (!node->isOccupied)
++ return false;
++ node->isOccupied = false;
++ mergeNodeWithNeighbors(node);
++ return true;
++ }
++
++ void AreaAllocator::mergeNodeWithNeighbors(AreaAllocatorNode *node)
++ {
++ bool done = false;
++ AreaAllocatorNode *parent = 0;
++ AreaAllocatorNode *current = 0;
++ AreaAllocatorNode *sibling;
++ while (!done) {
++ Q_ASSERT(node->isLeaf());
++ Q_ASSERT(!node->isOccupied);
++ if (node->parent == 0)
++ return; // No neighbors.
++
++ SplitType splitType = SplitType(node->parent->splitType);
++ done = true;
++
++ /* Special case. Might be faster than going through the general code path.
++ // Merge with sibling.
++ parent = node->parent;
++ sibling = (node == parent->left ? parent->right : parent->left);
++ if (sibling->isLeaf() && !sibling->isOccupied) {
++ Q_ASSERT(!sibling->right);
++ node = parent;
++ parent->isOccupied = false;
++ delete parent->left;
++ delete parent->right;
++ parent->left = parent->right = 0;
++ done = false;
++ continue;
++ }
++ */
++
++ // Merge with left neighbor.
++ current = node;
++ parent = current->parent;
++ while (parent && current == parent->left && parent->splitType == splitType) {
++ current = parent;
++ parent = parent->parent;
++ }
++
++ if (parent && parent->splitType == splitType) {
++ Q_ASSERT(current == parent->right);
++ Q_ASSERT(parent->left);
++
++ AreaAllocatorNode *neighbor = parent->left;
++ while (neighbor->right && neighbor->splitType == splitType)
++ neighbor = neighbor->right;
++
++ if (neighbor->isLeaf() && neighbor->parent->splitType == splitType && !neighbor->isOccupied) {
++ // Left neighbor can be merged.
++ parent->split = neighbor->parent->split;
++
++ parent = neighbor->parent;
++ sibling = neighbor == parent->left ? parent->right : parent->left;
++ AreaAllocatorNode **nodeRef = &m_root;
++ if (parent->parent) {
++ if (parent == parent->parent->left)
++ nodeRef = &parent->parent->left;
++ else
++ nodeRef = &parent->parent->right;
++ }
++ sibling->parent = parent->parent;
++ *nodeRef = sibling;
++ parent->left = parent->right = 0;
++ delete parent;
++ delete neighbor;
++ done = false;
++ }
++ }
++
++ // Merge with right neighbor.
++ current = node;
++ parent = current->parent;
++ while (parent && current == parent->right && parent->splitType == splitType) {
++ current = parent;
++ parent = parent->parent;
++ }
++
++ if (parent && parent->splitType == splitType) {
++ Q_ASSERT(current == parent->left);
++ Q_ASSERT(parent->right);
++
++ AreaAllocatorNode *neighbor = parent->right;
++ while (neighbor->left && neighbor->splitType == splitType)
++ neighbor = neighbor->left;
++
++ if (neighbor->isLeaf() && neighbor->parent->splitType == splitType && !neighbor->isOccupied) {
++ // Right neighbor can be merged.
++ parent->split = neighbor->parent->split;
++
++ parent = neighbor->parent;
++ sibling = neighbor == parent->left ? parent->right : parent->left;
++ AreaAllocatorNode **nodeRef = &m_root;
++ if (parent->parent) {
++ if (parent == parent->parent->left)
++ nodeRef = &parent->parent->left;
++ else
++ nodeRef = &parent->parent->right;
++ }
++ sibling->parent = parent->parent;
++ *nodeRef = sibling;
++ parent->left = parent->right = 0;
++ delete parent;
++ delete neighbor;
++ done = false;
++ }
++ }
++ } // end while (!done)
++ }
++
++ } // namespace Qt3DExtras
++
++ QT_END_NAMESPACE