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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+ \class QGraphicsSceneBspTreeIndex
+ \brief The QGraphicsSceneBspTreeIndex class provides an implementation of
+ a BSP indexing algorithm for discovering items in QGraphicsScene.
+ \since 4.6
+ \ingroup multimedia
+ \ingroup graphicsview-api
+ \mainclass
+ \internal
+
+ QGraphicsSceneBspTreeIndex index use a BSP(Binary Space Partitioning)
+ implementation to discover items quickly. This implementation is
+ very efficient for static scene. It has a depth that you can set.
+ The depth directly affects performance and memory usage; the latter
+ growing exponentially with the depth of the tree. With an optimal tree
+ depth, the index can instantly determine the locality of items, even
+ for scenes with thousands or millions of items. This also greatly improves
+ rendering performance.
+
+ By default, the value is 0, in which case Qt will guess a reasonable
+ default depth based on the size, location and number of items in the
+ scene. If these parameters change frequently, however, you may experience
+ slowdowns as the index retunes the depth internally. You can avoid
+ potential slowdowns by fixating the tree depth through setting this
+ property.
+
+ The depth of the tree and the size of the scene rectangle decide the
+ granularity of the scene's partitioning. The size of each scene segment is
+ determined by the following algorithm:
+
+ The BSP tree has an optimal size when each segment contains between 0 and
+ 10 items.
+
+ \sa QGraphicsScene, QGraphicsView, QGraphicsSceneIndex
+*/
+
+#include "qgraphicsscenebsptreeindex.h"
+
+#ifndef QT_NO_GRAPHICSVIEW
+
+#include "qgraphicsscenebsptreeindex_p.h"
+#include "qgraphicssceneindex_p.h"
+#include "qgraphicsitem_p.h"
+#include "qgraphicsscene_p.h"
+
+#include <QtCore/qmath.h>
+
+#include <QtCore/qdebug.h>
+
+QT_BEGIN_NAMESPACE
+
+static inline int intmaxlog(int n)
+{
+ return (n > 0 ? qMax(qCeil(qLn(qreal(n)) / qLn(qreal(2))), 5) : 0);
+}
+
+/*!
+ Constructs a private scene bsp index.
+*/
+QGraphicsSceneBspTreeIndexPrivate::QGraphicsSceneBspTreeIndexPrivate(QGraphicsScene *scene)
+ : QGraphicsSceneIndexPrivate(scene),
+ bspTreeDepth(0),
+ indexTimerId(0),
+ restartIndexTimer(false),
+ regenerateIndex(true),
+ lastItemCount(0),
+ purgePending(false),
+ sortCacheEnabled(false),
+ updatingSortCache(false)
+{
+}
+
+
+/*!
+ This method will update the BSP index by removing the items from the temporary
+ unindexed list and add them in the indexedItems list. This will also
+ update the growingItemsBoundingRect if needed. This will update the BSP
+ implementation as well.
+
+ \internal
+*/
+void QGraphicsSceneBspTreeIndexPrivate::_q_updateIndex()
+{
+ Q_Q(QGraphicsSceneBspTreeIndex);
+ if (!indexTimerId)
+ return;
+
+ QGraphicsScenePrivate * scenePrivate = q->scene()->d_func();
+ q->killTimer(indexTimerId);
+ indexTimerId = 0;
+
+ purgeRemovedItems();
+
+ // Add unindexedItems to indexedItems
+ QRectF unindexedItemsBoundingRect;
+ for (int i = 0; i < unindexedItems.size(); ++i) {
+ if (QGraphicsItem *item = unindexedItems.at(i)) {
+ unindexedItemsBoundingRect |= item->sceneBoundingRect();
+ if (!freeItemIndexes.isEmpty()) {
+ int freeIndex = freeItemIndexes.takeFirst();
+ item->d_func()->index = freeIndex;
+ indexedItems[freeIndex] = item;
+ } else {
+ item->d_func()->index = indexedItems.size();
+ indexedItems << item;
+ }
+ }
+ }
+
+ // Update growing scene rect.
+ QRectF oldGrowingItemsBoundingRect = scenePrivate->growingItemsBoundingRect;
+ scenePrivate->growingItemsBoundingRect |= unindexedItemsBoundingRect;
+
+ // Determine whether we should regenerate the BSP tree.
+ if (bspTreeDepth == 0) {
+ int oldDepth = intmaxlog(lastItemCount);
+ bspTreeDepth = intmaxlog(indexedItems.size());
+ static const int slack = 100;
+ if (bsp.leafCount() == 0 || (oldDepth != bspTreeDepth && qAbs(lastItemCount - indexedItems.size()) > slack)) {
+ // ### Crude algorithm.
+ regenerateIndex = true;
+ }
+ }
+
+ // Regenerate the tree.
+ if (regenerateIndex) {
+ regenerateIndex = false;
+ bsp.initialize(q->scene()->sceneRect(), bspTreeDepth);
+ unindexedItems = indexedItems;
+ lastItemCount = indexedItems.size();
+ q->scene()->update();
+
+ // Take this opportunity to reset our largest-item counter for
+ // untransformable items. When the items are inserted into the BSP
+ // tree, we'll get an accurate calculation.
+ scenePrivate->largestUntransformableItem = QRectF();
+ }
+
+ // Insert all unindexed items into the tree.
+ for (int i = 0; i < unindexedItems.size(); ++i) {
+ if (QGraphicsItem *item = unindexedItems.at(i)) {
+ QRectF rect = item->sceneBoundingRect();
+ if (item->d_ptr->ancestorFlags & QGraphicsItemPrivate::AncestorClipsChildren)
+ continue;
+
+ bsp.insertItem(item, rect);
+
+ // If the item ignores view transformations, update our
+ // largest-item-counter to ensure that the view can accurately
+ // discover untransformable items when drawing.
+ if (item->d_ptr->itemIsUntransformable()) {
+ QGraphicsItem *topmostUntransformable = item;
+ while (topmostUntransformable && (topmostUntransformable->d_ptr->ancestorFlags
+ & QGraphicsItemPrivate::AncestorIgnoresTransformations)) {
+ topmostUntransformable = topmostUntransformable->parentItem();
+ }
+ // ### Verify that this is the correct largest untransformable rectangle.
+ scenePrivate->largestUntransformableItem |= item->mapToItem(topmostUntransformable, item->boundingRect()).boundingRect();
+ }
+ }
+ }
+ unindexedItems.clear();
+
+ // Notify scene rect changes.
+ if (!scenePrivate->hasSceneRect && scenePrivate->growingItemsBoundingRect != oldGrowingItemsBoundingRect)
+ emit q->scene()->sceneRectChanged(scenePrivate->growingItemsBoundingRect);
+}
+
+
+/*!
+ \internal
+
+ Removes stale pointers from all data structures.
+*/
+void QGraphicsSceneBspTreeIndexPrivate::purgeRemovedItems()
+{
+ if (!purgePending && removedItems.isEmpty())
+ return;
+
+ // Remove stale items from the BSP tree.
+ bsp.removeItems(removedItems);
+ // Purge this list.
+ removedItems.clear();
+ freeItemIndexes.clear();
+ for (int i = 0; i < indexedItems.size(); ++i) {
+ if (!indexedItems.at(i))
+ freeItemIndexes << i;
+ }
+ purgePending = false;
+}
+
+/*!
+ \internal
+
+ Starts or restarts the timer used for reindexing unindexed items.
+*/
+void QGraphicsSceneBspTreeIndexPrivate::startIndexTimer(int interval)
+{
+ Q_Q(QGraphicsSceneBspTreeIndex);
+ if (indexTimerId) {
+ restartIndexTimer = true;
+ } else {
+ indexTimerId = q->startTimer(interval);
+ }
+}
+
+/*!
+ \internal
+*/
+void QGraphicsSceneBspTreeIndexPrivate::resetIndex()
+{
+ purgeRemovedItems();
+ for (int i = 0; i < indexedItems.size(); ++i) {
+ if (QGraphicsItem *item = indexedItems.at(i)) {
+ item->d_ptr->index = -1;
+ unindexedItems << item;
+ }
+ }
+ indexedItems.clear();
+ freeItemIndexes.clear();
+ regenerateIndex = true;
+ startIndexTimer();
+}
+
+/*!
+ \internal
+*/
+void QGraphicsSceneBspTreeIndexPrivate::climbTree(QGraphicsItem *item, int *stackingOrder)
+{
+ if (!item->d_ptr->children.isEmpty()) {
+ QList<QGraphicsItem *> childList = item->d_ptr->children;
+ qSort(childList.begin(), childList.end(), qt_closestLeaf);
+ for (int i = 0; i < childList.size(); ++i) {
+ QGraphicsItem *item = childList.at(i);
+ if (!(item->flags() & QGraphicsItem::ItemStacksBehindParent))
+ climbTree(childList.at(i), stackingOrder);
+ }
+ item->d_ptr->globalStackingOrder = (*stackingOrder)++;
+ for (int i = 0; i < childList.size(); ++i) {
+ QGraphicsItem *item = childList.at(i);
+ if (item->flags() & QGraphicsItem::ItemStacksBehindParent)
+ climbTree(childList.at(i), stackingOrder);
+ }
+ } else {
+ item->d_ptr->globalStackingOrder = (*stackingOrder)++;
+ }
+}
+
+/*!
+ \internal
+*/
+void QGraphicsSceneBspTreeIndexPrivate::_q_updateSortCache()
+{
+ Q_Q(QGraphicsSceneBspTreeIndex);
+ _q_updateIndex();
+
+ if (!sortCacheEnabled || !updatingSortCache)
+ return;
+
+ updatingSortCache = false;
+ int stackingOrder = 0;
+
+ QList<QGraphicsItem *> topLevels;
+
+ for (int i = 0; i < q->items().count(); ++i) {
+ QGraphicsItem *item = q->items().at(i);
+ if (item && item->parentItem() == 0)
+ topLevels << item;
+ }
+
+ qSort(topLevels.begin(), topLevels.end(), qt_closestLeaf);
+ for (int i = 0; i < topLevels.size(); ++i)
+ climbTree(topLevels.at(i), &stackingOrder);
+}
+
+/*!
+ \internal
+*/
+void QGraphicsSceneBspTreeIndexPrivate::invalidateSortCache()
+{
+ Q_Q(QGraphicsSceneBspTreeIndex);
+ if (!sortCacheEnabled || updatingSortCache)
+ return;
+
+ updatingSortCache = true;
+ QMetaObject::invokeMethod(q, "_q_updateSortCache", Qt::QueuedConnection);
+}
+
+/*!
+ Returns true if \a item1 is on top of \a item2.
+
+ \internal
+*/
+bool QGraphicsSceneBspTreeIndexPrivate::closestItemFirst_withoutCache(const QGraphicsItem *item1, const QGraphicsItem *item2)
+{
+ // Siblings? Just check their z-values.
+ const QGraphicsItemPrivate *d1 = item1->d_ptr;
+ const QGraphicsItemPrivate *d2 = item2->d_ptr;
+ if (d1->parent == d2->parent)
+ return qt_closestLeaf(item1, item2);
+
+ // Find common ancestor, and each item's ancestor closest to the common
+ // ancestor.
+ int item1Depth = d1->depth;
+ int item2Depth = d2->depth;
+ const QGraphicsItem *p = item1;
+ const QGraphicsItem *t1 = item1;
+ while (item1Depth > item2Depth && (p = p->d_ptr->parent)) {
+ if (p == item2) {
+ // item2 is one of item1's ancestors; item1 is on top
+ return !(t1->d_ptr->flags & QGraphicsItem::ItemStacksBehindParent);
+ }
+ t1 = p;
+ --item1Depth;
+ }
+ p = item2;
+ const QGraphicsItem *t2 = item2;
+ while (item2Depth > item1Depth && (p = p->d_ptr->parent)) {
+ if (p == item1) {
+ // item1 is one of item2's ancestors; item1 is not on top
+ return (t2->d_ptr->flags & QGraphicsItem::ItemStacksBehindParent);
+ }
+ t2 = p;
+ --item2Depth;
+ }
+
+ // item1Ancestor is now at the same level as item2Ancestor, but not the same.
+ const QGraphicsItem *a1 = t1;
+ const QGraphicsItem *a2 = t2;
+ while (a1) {
+ const QGraphicsItem *p1 = a1;
+ const QGraphicsItem *p2 = a2;
+ a1 = a1->parentItem();
+ a2 = a2->parentItem();
+ if (a1 && a1 == a2)
+ return qt_closestLeaf(p1, p2);
+ }
+
+ // No common ancestor? Then just compare the items' toplevels directly.
+ return qt_closestLeaf(t1->topLevelItem(), t2->topLevelItem());
+}
+
+/*!
+ Returns true if \a item2 is on top of \a item1.
+
+ \internal
+*/
+bool QGraphicsSceneBspTreeIndexPrivate::closestItemLast_withoutCache(const QGraphicsItem *item1, const QGraphicsItem *item2)
+{
+ return closestItemFirst_withoutCache(item2, item1);
+}
+
+/*!
+ Sort a list of \a itemList in a specific \a order and use the cache if requested.
+
+ \internal
+*/
+void QGraphicsSceneBspTreeIndexPrivate::sortItems(QList<QGraphicsItem *> *itemList, Qt::SortOrder order,
+ bool sortCacheEnabled)
+{
+ if (sortCacheEnabled) {
+ if (order == Qt::AscendingOrder) {
+ qSort(itemList->begin(), itemList->end(), closestItemFirst_withCache);
+ } else if (order == Qt::DescendingOrder) {
+ qSort(itemList->begin(), itemList->end(), closestItemLast_withCache);
+ }
+ } else {
+ if (order == Qt::AscendingOrder) {
+ qSort(itemList->begin(), itemList->end(), closestItemFirst_withoutCache);
+ } else if (order == Qt::DescendingOrder) {
+ qSort(itemList->begin(), itemList->end(), closestItemLast_withoutCache);
+ }
+ }
+}
+
+/*!
+ Constructs a BSP scene index for the given \a scene.
+*/
+QGraphicsSceneBspTreeIndex::QGraphicsSceneBspTreeIndex(QGraphicsScene *scene)
+ : QGraphicsSceneIndex(*new QGraphicsSceneBspTreeIndexPrivate(scene), scene)
+{
+
+}
+
+/*!
+ \reimp
+ Return the rect indexed by the BSP index.
+*/
+QRectF QGraphicsSceneBspTreeIndex::indexedRect() const
+{
+ Q_D(const QGraphicsSceneBspTreeIndex);
+ const_cast<QGraphicsSceneBspTreeIndexPrivate*>(d)->_q_updateIndex();
+ return scene()->d_func()->hasSceneRect ? scene()->d_func()->sceneRect : scene()->d_func()->growingItemsBoundingRect;
+}
+
+/*!
+ \reimp
+ Clear the all the BSP index.
+*/
+void QGraphicsSceneBspTreeIndex::clear()
+{
+ Q_D(QGraphicsSceneBspTreeIndex);
+ d->bsp.clear();
+ d->lastItemCount = 0;
+ d->freeItemIndexes.clear();
+ d->indexedItems.clear();
+ d->unindexedItems.clear();
+}
+
+/*!
+ Add the \a item into the BSP index.
+*/
+void QGraphicsSceneBspTreeIndex::addItem(QGraphicsItem *item)
+{
+ Q_D(QGraphicsSceneBspTreeIndex);
+ // Prevent reusing a recently deleted pointer: purge all removed items
+ // from our lists.
+ d->purgeRemovedItems();
+
+ // Invalidate any sort caching; arrival of a new item means we need to
+ // resort.
+ // Update the scene's sort cache settings.
+ item->d_ptr->globalStackingOrder = -1;
+ d->invalidateSortCache();
+
+ // Indexing requires sceneBoundingRect(), but because \a item might
+ // not be completely constructed at this point, we need to store it in
+ // a temporary list and schedule an indexing for later.
+ d->unindexedItems << item;
+ item->d_func()->index = -1;
+ d->startIndexTimer(0);
+}
+
+/*!
+ This really add the item in the BSP.
+ \internal
+*/
+void QGraphicsSceneBspTreeIndexPrivate::addToIndex(QGraphicsItem *item)
+{
+ if (item->d_func()->index != -1) {
+ bsp.insertItem(item, item->sceneBoundingRect());
+ foreach (QGraphicsItem *child, item->children())
+ child->addToIndex();
+ } else {
+ // The BSP tree is regenerated if the number of items grows to a
+ // certain threshold, or if the bounding rect of the graph doubles in
+ // size.
+ startIndexTimer();
+ }
+}
+
+/*!
+ Remove the \a item from the BSP index.
+*/
+void QGraphicsSceneBspTreeIndex::removeItem(QGraphicsItem *item)
+{
+ Q_D(QGraphicsSceneBspTreeIndex);
+ // Note: This will access item's sceneBoundingRect(), which (as this is
+ // C++) is why we cannot call removeItem() from QGraphicsItem's
+ // destructor.
+ d->removeFromIndex(item);
+
+ // Invalidate any sort caching; arrival of a new item means we need to
+ // resort.
+ d->invalidateSortCache();
+
+ // Remove from our item lists.
+ int index = item->d_func()->index;
+ if (index != -1) {
+ d->freeItemIndexes << index;
+ d->indexedItems[index] = 0;
+ } else {
+ d->unindexedItems.removeAll(item);
+ }
+}
+
+/*!
+ \reimp
+ Delete the \a item from the BSP index (without accessing its boundingRect).
+*/
+void QGraphicsSceneBspTreeIndex::deleteItem(QGraphicsItem *item)
+{
+ Q_D(QGraphicsSceneBspTreeIndex);
+ // Invalidate any sort caching; arrival of a new item means we need to
+ // resort.
+ d->invalidateSortCache();
+
+ int index = item->d_func()->index;
+ if (index != -1) {
+ // Important: The index is useless until purgeRemovedItems() is
+ // called.
+ d->indexedItems[index] = (QGraphicsItem *)0;
+ if (!d->purgePending) {
+ d->purgePending = true;
+ scene()->update();
+ }
+ d->removedItems << item;
+ } else {
+ // Recently added items are purged immediately. unindexedItems() never
+ // contains stale items.
+ d->unindexedItems.removeAll(item);
+ scene()->update();
+ }
+}
+
+/*!
+ Really remove the item from the BSP
+ \internal
+*/
+void QGraphicsSceneBspTreeIndexPrivate::removeFromIndex(QGraphicsItem *item)
+{
+ if (item->d_func()->ancestorFlags & QGraphicsItemPrivate::AncestorClipsChildren) {
+ // ### remove from child index only if applicable
+ return;
+ }
+ int index = item->d_func()->index;
+ if (index != -1) {
+ bsp.removeItem(item, item->sceneBoundingRect());
+ freeItemIndexes << index;
+ indexedItems[index] = 0;
+ item->d_func()->index = -1;
+ unindexedItems << item;
+
+ //prepareGeometryChange will call prepareBoundingRectChange
+ foreach (QGraphicsItem *child, item->children())
+ child->prepareGeometryChange();
+ }
+ startIndexTimer();
+}
+
+/*!
+ \reimp
+ Update the BSP when the \a item 's bounding rect has changed.
+*/
+void QGraphicsSceneBspTreeIndex::prepareBoundingRectChange(const QGraphicsItem *item)
+{
+ Q_D(QGraphicsSceneBspTreeIndex);
+ // Note: This will access item's sceneBoundingRect(), which (as this is
+ // C++) is why we cannot call removeItem() from QGraphicsItem's
+ // destructor.
+ d->removeFromIndex(const_cast<QGraphicsItem *>(item));
+}
+
+/*!
+ Returns an estimation visible items that are either inside or
+ intersect with the specified \a rect and return a list sorted using \a order.
+
+ \a deviceTransform is the transformation apply to the view.
+
+*/
+QList<QGraphicsItem *> QGraphicsSceneBspTreeIndex::estimateItems(const QRectF &rect, Qt::SortOrder order, const QTransform &deviceTransform) const
+{
+ Q_D(const QGraphicsSceneBspTreeIndex);
+ const_cast<QGraphicsSceneBspTreeIndexPrivate*>(d)->purgeRemovedItems();
+ const_cast<QGraphicsSceneBspTreeIndexPrivate*>(d)->_q_updateSortCache();
+
+ QList<QGraphicsItem *> rectItems = d->bsp.items(rect);
+ // Fill in with any unindexed items
+ for (int i = 0; i < d->unindexedItems.size(); ++i) {
+ if (QGraphicsItem *item = d->unindexedItems.at(i)) {
+ if (!item->d_ptr->itemDiscovered && item->d_ptr->visible && !(item->d_ptr->ancestorFlags & QGraphicsItemPrivate::AncestorClipsChildren)) {
+ QRectF boundingRect = item->sceneBoundingRect();
+ if (QRectF_intersects(boundingRect, rect)) {
+ item->d_ptr->itemDiscovered = 1;
+ rectItems << item;
+ }
+ }
+ }
+ }
+
+ // Reset the discovered state of all discovered items
+ for (int i = 0; i < rectItems.size(); ++i)
+ rectItems.at(i)->d_func()->itemDiscovered = 0;
+
+ d->sortItems(&rectItems, order, d->sortCacheEnabled);
+
+ return rectItems;
+}
+
+
+/*!
+ \fn QList<QGraphicsItem *> QGraphicsSceneBspTreeIndex::items(Qt::SortOrder order = Qt::AscendingOrder) const;
+
+ Return all items in the BSP index and sort them using \a order.
+*/
+QList<QGraphicsItem *> QGraphicsSceneBspTreeIndex::items(Qt::SortOrder order) const
+{
+ Q_D(const QGraphicsSceneBspTreeIndex);
+ const_cast<QGraphicsSceneBspTreeIndexPrivate*>(d)->purgeRemovedItems();
+ QList<QGraphicsItem *> itemList;
+ // If freeItemIndexes is empty, we know there are no holes in indexedItems and
+ // unindexedItems.
+ if (d->freeItemIndexes.isEmpty()) {
+ if (d->unindexedItems.isEmpty()) {
+ itemList = d->indexedItems;
+ } else {
+ itemList = d->indexedItems + d->unindexedItems;
+ }
+ } else {
+ // Rebuild the list of items to avoid holes. ### We could also just
+ // compress the item lists at this point.
+ foreach (QGraphicsItem *item, d->indexedItems + d->unindexedItems) {
+ if (item)
+ itemList << item;
+ }
+ }
+ if (order != -1) {
+ //We sort descending order
+ d->sortItems(&itemList, order, d->sortCacheEnabled);
+ }
+ return itemList;
+}
+
+/*!
+ \property QGraphicsSceneBspTreeIndex::bspTreeDepth
+ \brief the depth of the BSP index tree
+ \since 4.6
+
+ This value determines the depth of BSP tree. The depth
+ directly affects performance and memory usage; the latter
+ growing exponentially with the depth of the tree. With an optimal tree
+ depth, the index can instantly determine the locality of items, even
+ for scenes with thousands or millions of items. This also greatly improves
+ rendering performance.
+
+ By default, the value is 0, in which case Qt will guess a reasonable
+ default depth based on the size, location and number of items in the
+ scene. If these parameters change frequently, however, you may experience
+ slowdowns as the index retunes the depth internally. You can avoid
+ potential slowdowns by fixating the tree depth through setting this
+ property.
+
+ The depth of the tree and the size of the scene rectangle decide the
+ granularity of the scene's partitioning. The size of each scene segment is
+ determined by the following algorithm:
+
+ The BSP tree has an optimal size when each segment contains between 0 and
+ 10 items.
+
+*/
+int QGraphicsSceneBspTreeIndex::bspTreeDepth()
+{
+ Q_D(const QGraphicsSceneBspTreeIndex);
+ return d->bspTreeDepth;
+}
+
+void QGraphicsSceneBspTreeIndex::setBspTreeDepth(int depth)
+{
+ Q_D(QGraphicsSceneBspTreeIndex);
+ d->bspTreeDepth = depth;
+ d->resetIndex();
+}
+
+/*!
+ \reimp
+
+ This method react to the \a rect change of the scene and
+ reset the BSP tree index.
+*/
+void QGraphicsSceneBspTreeIndex::sceneRectChanged(const QRectF &rect)
+{
+ Q_D(QGraphicsSceneBspTreeIndex);
+ d->sceneRect = rect;
+ d->resetIndex();
+}
+
+/*!
+ \reimp
+
+ This method react to the \a change of the \a item and use the \a value to
+ update the BSP tree if necessary.
+
+*/
+void QGraphicsSceneBspTreeIndex::itemChanged(const QGraphicsItem *item, QGraphicsItem::GraphicsItemChange change, const QVariant &value)
+{
+ Q_D(QGraphicsSceneBspTreeIndex);
+ switch (change) {
+ case QGraphicsItem::ItemZValueChange:
+ case QGraphicsItem::ItemParentChange: {
+ d->invalidateSortCache();
+ break;
+ }
+ default:
+ break;
+ }
+ return QGraphicsSceneIndex::itemChanged(item, change, value);
+}
+/*!
+ \reimp
+
+ Used to catch the timer event.
+
+ \internal
+*/
+bool QGraphicsSceneBspTreeIndex::event(QEvent *event)
+{
+ Q_D(QGraphicsSceneBspTreeIndex);
+ switch (event->type()) {
+ case QEvent::Timer:
+ if (d->indexTimerId && static_cast<QTimerEvent *>(event)->timerId() == d->indexTimerId) {
+ if (d->restartIndexTimer) {
+ d->restartIndexTimer = false;
+ } else {
+ // this call will kill the timer
+ d->_q_updateIndex();
+ }
+ }
+ // Fallthrough intended - support timers in subclasses.
+ default:
+ return QObject::event(event);
+ }
+ return true;
+}
+
+QT_END_NAMESPACE
+
+#include "moc_qgraphicsscenebsptreeindex.cpp"
+
+#endif // QT_NO_GRAPHICSVIEW
+