QAbstractItemView: optimize handling of editors for view with large numbers of editors.

This change improves algorithmic time complexity for item views during
operations which directly (or indirectly such as layout) require
bi-directional lookups between model indices and persistent editor widgets.
The previous implementation scaled as O(n^2) due to the unordered search
through a QVector.

Implementations that use large numbers of persistent editors are most
dramatically improved. In one "real world" test case with 648 persistent
editors, profiling indicates an improvement of layout from 45 seconds
to 8 seconds with this change alone.

Reviewed-by: Olivier Goffart
Merge-Request: 2452

1 files changed, 2 insertions, 2 deletions

diff --git a/src/gui/itemviews/qtableview.cpp b/src/gui/itemviews/qtableview.cpp
index e9e2e38..d8fef55 100644
--- a/src/gui/itemviews/qtableview.cpp
+++ b/src/gui/itemviews/qtableview.cpp
@@ -2159,7 +2159,7 @@ int QTableView::sizeHintForRow(int row) const
             option.rect.setWidth(columnWidth(index.column()));
         }
         
-        QWidget *editor = d->editorForIndex(index).editor;
+        QWidget *editor = d->editorForIndex(index).widget.data();
         if (editor && d->persistent.contains(editor)) {
             hint = qMax(hint, editor->sizeHint().height());
             int min = editor->minimumSize().height();
@@ -2212,7 +2212,7 @@ int QTableView::sizeHintForColumn(int column) const
             continue;
         index = d->model->index(logicalRow, column, d->root);
         
-        QWidget *editor = d->editorForIndex(index).editor;
+        QWidget *editor = d->editorForIndex(index).widget.data();
         if (editor && d->persistent.contains(editor)) {
             hint = qMax(hint, editor->sizeHint().width());
             int min = editor->minimumSize().width();