QTreeView: Remove a lot of useless and slow code.

Since commit cd2afafbc9c29393a80d415145c49eb5f439da55, we are always
doing full relayout when adding or removing rows. So there is no point
of doing the expensive incremental update of the viewItems.

This has also the nice side effect to fix QTCREATORBUG-886
(see comment in the task)

Reviewed-by: Thierry

2 files changed, 28 insertions, 213 deletions

diff --git a/src/gui/itemviews/qtreeview.cpp b/src/gui/itemviews/qtreeview.cpp
index 4135ba0..ada3936 100644
--- a/src/gui/itemviews/qtreeview.cpp
+++ b/src/gui/itemviews/qtreeview.cpp
@@ -1997,6 +1997,24 @@ QModelIndex QTreeView::indexBelow(const QModelIndex &index) const
 void QTreeView::doItemsLayout()
 {
     Q_D(QTreeView);
+    if (d->hasRemovedItems) {
+        //clean the QSet that may contains old (and this invalid) indexes
+        d->hasRemovedItems = false;
+        QSet<QPersistentModelIndex>::iterator it = d->expandedIndexes.begin();
+        while (it != d->expandedIndexes.constEnd()) {
+            if (!it->isValid())
+                it = d->expandedIndexes.erase(it);
+            else
+                ++it;
+        }
+        it = d->hiddenIndexes.begin();
+        while (it != d->hiddenIndexes.constEnd()) {
+            if (!it->isValid())
+                it = d->hiddenIndexes.erase(it);
+            else
+                ++it;
+        }
+    }
     d->viewItems.clear(); // prepare for new layout
     QModelIndex parent = d->root;
     if (d->model->hasChildren(parent)) {
@@ -2406,24 +2424,6 @@ void QTreeView::reexpand()
 }
 
 /*!
-  \internal
-  This function assume that left is a (grand-)child of the parent of left.
-*/
-static bool treeViewItemLessThanInInsert(const QTreeViewItem &left, const QTreeViewItem &right)
-{
-    if (left.level != right.level) {
-        Q_ASSERT(left.level > right.level);
-        QModelIndex leftParent = left.index.parent();
-        QModelIndex rightParent = right.index.parent();
-        // computer parent, don't get
-        while (leftParent.isValid() && leftParent.parent() != rightParent)
-            leftParent = leftParent.parent();
-        return (leftParent.row() < right.index.row());
-    }
-    return (left.index.row() < right.index.row());
-}
-
-/*!
   Informs the view that the rows from the \a start row to the \a end row
   inclusive have been inserted into the \a parent model item.
 */
@@ -2452,83 +2452,6 @@ void QTreeView::rowsInserted(const QModelIndex &parent, int start, int end)
     const int parentItem = d->viewIndex(parent);
     if (((parentItem != -1) && d->viewItems.at(parentItem).expanded && updatesEnabled())
         || (parent == d->root)) {
-        const uint childLevel = (parentItem == -1)
-                                ? uint(0) : d->viewItems.at(parentItem).level + 1;
-        const int firstChildItem = parentItem + 1;
-        const int lastChildItem = firstChildItem + ((parentItem == -1)
-                                                    ? d->viewItems.count()
-                                                    : d->viewItems.at(parentItem).total) - 1;
-
-        if (parentRowCount == end + 1 && start > 0) {
-            //need to Update hasMoreSiblings
-            int previousRow = start - 1;
-            QModelIndex previousSibilingModelIndex = d->model->index(previousRow, 0, parent);
-            bool isHidden = d->isRowHidden(previousSibilingModelIndex);
-            while (isHidden && previousRow > 0) {
-                previousRow--;
-                previousSibilingModelIndex = d->model->index(previousRow, 0, parent);
-                isHidden = d->isRowHidden(previousSibilingModelIndex);
-            }
-            if (!isHidden) {
-                const int previousSibilling = d->viewIndex(previousSibilingModelIndex);
-                if(previousSibilling != -1)
-                    d->viewItems[previousSibilling].hasMoreSiblings = true;
-            }
-        }
-
-        QVector<QTreeViewItem> insertedItems(delta);
-        for (int i = 0; i < delta; ++i) {
-            QTreeViewItem &item = insertedItems[i];
-            item.index = d->model->index(i + start, 0, parent);
-            item.parentItem = parentItem;
-            item.level = childLevel;
-            item.hasChildren = d->hasVisibleChildren(item.index);
-            item.hasMoreSiblings = !((i == delta - 1) && (parentRowCount == end +1));
-        }
-        if (d->viewItems.isEmpty())
-            d->defaultItemHeight = indexRowSizeHint(insertedItems[0].index);
-
-        int insertPos;
-        if (lastChildItem < firstChildItem) { // no children
-            insertPos = firstChildItem;
-        } else {
-            // do a binary search to figure out where to insert
-            QVector<QTreeViewItem>::iterator it;
-            it = qLowerBound(d->viewItems.begin() + firstChildItem,
-                             d->viewItems.begin() + lastChildItem + 1,
-                             insertedItems.at(0), treeViewItemLessThanInInsert);
-            insertPos = it - d->viewItems.begin();
-
-            // update stale model indexes of siblings
-            for (int item = insertPos; item <= lastChildItem; ) {
-                Q_ASSERT(d->viewItems.at(item).level == childLevel);
-                const QModelIndex modelIndex = d->viewItems.at(item).index;
-                //Q_ASSERT(modelIndex.parent() == parent);
-                d->viewItems[item].index = d->model->index(
-                    modelIndex.row() + delta, modelIndex.column(), parent);
-
-                if (!d->viewItems[item].index.isValid()) {
-                    // Something really bad is happening, a bad model is
-                    // often the cause.  We can't optimize in this case :(
-                    qWarning() << "QTreeView::rowsInserted internal representation of the model has been corrupted, resetting.";
-                    doItemsLayout();
-                    return;
-                }
-
-                item += d->viewItems.at(item).total + 1;
-            }
-        }
-
-        d->insertViewItems(insertPos, delta, insertedItems.at(0));
-        if (delta > 1) {
-            qCopy(insertedItems.begin() + 1, insertedItems.end(),
-                  d->viewItems.begin() + insertPos + 1);
-        }
-
-        if (parentItem != -1)
-            d->viewItems[parentItem].hasChildren = true;
-        d->updateChildCount(parentItem, delta);
-
         d->doDelayedItemsLayout();
     } else if ((parentItem != -1) && d->viewItems.at(parentItem).expanded) {
         d->doDelayedItemsLayout();
@@ -2547,8 +2470,8 @@ void QTreeView::rowsInserted(const QModelIndex &parent, int start, int end)
 void QTreeView::rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end)
 {
     Q_D(QTreeView);
-    d->rowsRemoved(parent, start, end, false);
     QAbstractItemView::rowsAboutToBeRemoved(parent, start, end);
+    d->viewItems.clear();
 }
 
 /*!
@@ -2560,7 +2483,10 @@ void QTreeView::rowsAboutToBeRemoved(const QModelIndex &parent, int start, int e
 void QTreeView::rowsRemoved(const QModelIndex &parent, int start, int end)
 {
     Q_D(QTreeView);
-    d->rowsRemoved(parent, start, end, true);
+    d->viewItems.clear();
+    d->doDelayedItemsLayout();
+    d->hasRemovedItems = true;
+    d->_q_rowsRemoved(parent, start, end);
 }
 
 /*!
@@ -3398,7 +3324,7 @@ int QTreeViewPrivate::viewIndex(const QModelIndex &_index) const
     const int totalCount = viewItems.count();
     const QModelIndex index = _index.sibling(_index.row(), 0);
     const int row = index.row();
-    const quint64 internalId = index.internalId();
+    const qint64 internalId = index.internalId();
 
     // We start nearest to the lastViewedItem
     int localCount = qMin(lastViewedItem - 1, totalCount - lastViewedItem);
@@ -3751,118 +3677,6 @@ bool QTreeViewPrivate::hasVisibleChildren(const QModelIndex& parent) const
     return false;
 }
 
-void QTreeViewPrivate::rowsRemoved(const QModelIndex &parent,
-                                   int start, int end, bool after)
-{
-    // if we are going to do a complete relayout anyway, there is no need to update
-    if (delayedPendingLayout) {
-        _q_rowsRemoved(parent, start, end);
-        return;
-    }
-
-    const int parentItem = viewIndex(parent);
-    if ((parentItem != -1) || (parent == root)) {
-
-        const uint childLevel = (parentItem == -1)
-                                ? uint(0) : viewItems.at(parentItem).level + 1;
-        Q_UNUSED(childLevel); // unused in release mode, used in assert below
-
-        const int firstChildItem = parentItem + 1;
-        int lastChildItem = firstChildItem + ((parentItem == -1)
-                                              ? viewItems.count()
-                                              : viewItems.at(parentItem).total) - 1;
-
-        const int delta = end - start + 1;
-
-        int previousSibiling = -1;
-        int removedCount = 0;
-        for (int item = firstChildItem; item <= lastChildItem; ) {
-            Q_ASSERT(viewItems.at(item).level == childLevel);
-            const QModelIndex modelIndex = viewItems.at(item).index;
-            //Q_ASSERT(modelIndex.parent() == parent);
-            const int count = viewItems.at(item).total + 1;
-            if (modelIndex.row() < start) {
-                previousSibiling = item;
-                // not affected by the removal
-                item += count;
-            } else if (modelIndex.row() <= end) {
-                // removed
-                removeViewItems(item, count);
-                removedCount += count;
-                lastChildItem -= count;
-            } else {
-                if (after) {
-                    // moved; update the model index
-                    viewItems[item].index = model->index(
-                        modelIndex.row() - delta, modelIndex.column(), parent);
-                }
-                item += count;
-            }
-        }
-
-        if (previousSibiling != -1 && after && model->rowCount(parent) == start)
-            viewItems[previousSibiling].hasMoreSiblings = false;
-
-        if (parentItem != -1) {
-            if (viewItems.at(parentItem).expanded) {
-                updateChildCount(parentItem, -removedCount);
-                if (viewItems.at(parentItem).total == 0)
-                    viewItems[parentItem].hasChildren = false; //every children have been removed;
-            } else if (viewItems[parentItem].hasChildren && !hasVisibleChildren(parent)) {
-                viewItems[parentItem].hasChildren = false;
-            }
-        }
-        if (after) {
-            doDelayedItemsLayout();
-        } else {
-            //we have removed items: we should at least update the scroll bar values.
-            // They are used to determine the item geometry.
-            updateScrollBars();
-        }
-    } else {
-        // If an ancestor of root is removed then relayout
-        QModelIndex idx = root;
-        while (idx.isValid()) {
-            idx = idx.parent();
-            if (idx == parent) {
-                doDelayedItemsLayout();
-                break;
-            }
-        }
-    }
-    _q_rowsRemoved(parent, start, end);
-
-    QSet<QPersistentModelIndex>::iterator it = expandedIndexes.begin();
-    while (it != expandedIndexes.constEnd()) {
-        if (!it->isValid())
-            it = expandedIndexes.erase(it);
-        else
-            ++it;
-    }
-    it = hiddenIndexes.begin();
-    while (it != hiddenIndexes.constEnd()) {
-        if (!it->isValid())
-            it = hiddenIndexes.erase(it);
-        else
-            ++it;
-    }
-}
-
-void QTreeViewPrivate::updateChildCount(const int parentItem, const int delta)
-{
-    if ((parentItem != -1) && delta) {
-        int level = viewItems.at(parentItem).level;
-        int item = parentItem;
-        do {
-            Q_ASSERT(item >= 0);
-            for ( ; int(viewItems.at(item).level) != level; --item) ;
-            viewItems[item].total += delta;
-            --level;
-        } while (level >= 0);
-    }
-}
-
-
 void QTreeViewPrivate::_q_sortIndicatorChanged(int column, Qt::SortOrder order)
 {
     model->sort(column, order);
diff --git a/src/gui/itemviews/qtreeview_p.h b/src/gui/itemviews/qtreeview_p.h
index 48997b7..261af31 100644
--- a/src/gui/itemviews/qtreeview_p.h
+++ b/src/gui/itemviews/qtreeview_p.h
@@ -91,7 +91,7 @@ public:
           expandsOnDoubleClick(true),
           allColumnsShowFocus(false), current(0), spanning(false),
           animationsEnabled(false), columnResizeTimerID(0),
-          autoExpandDelay(-1), hoverBranch(-1), geometryRecursionBlock(false) {}
+          autoExpandDelay(-1), hoverBranch(-1), geometryRecursionBlock(false), hasRemovedItems(false) {}
 
     ~QTreeViewPrivate() {}
     void initialize();
@@ -165,8 +165,6 @@ public:
     QPair<int,int> startAndEndColumns(const QRect &rect) const;
 
     void updateChildCount(const int parentItem, const int delta);
-    void rowsRemoved(const QModelIndex &parent,
-                     int start, int end, bool before);
 
     void paintAlternatingRowColors(QPainter *painter, QStyleOptionViewItemV4 *option, int y, int bottom) const;
 
@@ -242,6 +240,9 @@ public:
 
     // used for blocking recursion when calling setViewportMargins from updateGeometries
     bool geometryRecursionBlock;
+
+    // If we should clean the set
+    bool hasRemovedItems;
 };
 
 QT_END_NAMESPACE