From 43ed09fed59d55a8792fad87ef9a75382b5c60ff Mon Sep 17 00:00:00 2001
From: Christian Ehrlicher <ch.ehrlicher@gmx.de>
Date: Sat, 30 Jun 2018 14:49:05 +0200
Subject: QListView: Speedup handling of hidden items

Instead iterating through all rows to get the number of hidden items,
iterate over the hidden items which are fewer items.
Also don't create a temporary vector with visible flow positions by
remembering the count of hidden items before the working index and
adjusting them appropriately which gives a significant performance
boost when working with a large data set.

[ChangeLog][QtWidgets][QListWidget] Speedup handling of hidden items
when working with large data sets

Task-number: QTBUG-68977
Change-Id: I599b6e97945c245f02229145baad8363ec2bf2f5
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>
---
 tests/benchmarks/widgets/itemviews/itemviews.pro   |  3 +-
 .../widgets/itemviews/qlistview/qlistview.pro      |  7 +++
 .../widgets/itemviews/qlistview/tst_qlistview.cpp  | 68 ++++++++++++++++++++++
 3 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 tests/benchmarks/widgets/itemviews/qlistview/qlistview.pro
 create mode 100644 tests/benchmarks/widgets/itemviews/qlistview/tst_qlistview.cpp

(limited to 'tests/benchmarks')

diff --git a/tests/benchmarks/widgets/itemviews/itemviews.pro b/tests/benchmarks/widgets/itemviews/itemviews.pro
index a23cdf7b97..0c3256f307 100644
--- a/tests/benchmarks/widgets/itemviews/itemviews.pro
+++ b/tests/benchmarks/widgets/itemviews/itemviews.pro
@@ -1,4 +1,5 @@
 TEMPLATE = subdirs
 SUBDIRS = \
         qtableview \
-        qheaderview
+        qheaderview \
+        qlistview
diff --git a/tests/benchmarks/widgets/itemviews/qlistview/qlistview.pro b/tests/benchmarks/widgets/itemviews/qlistview/qlistview.pro
new file mode 100644
index 0000000000..68537d09ea
--- /dev/null
+++ b/tests/benchmarks/widgets/itemviews/qlistview/qlistview.pro
@@ -0,0 +1,7 @@
+QT += widgets testlib
+
+TEMPLATE = app
+TARGET = tst_bench_qlistview
+
+SOURCES += tst_qlistview.cpp
+
diff --git a/tests/benchmarks/widgets/itemviews/qlistview/tst_qlistview.cpp b/tests/benchmarks/widgets/itemviews/qlistview/tst_qlistview.cpp
new file mode 100644
index 0000000000..01496743c2
--- /dev/null
+++ b/tests/benchmarks/widgets/itemviews/qlistview/tst_qlistview.cpp
@@ -0,0 +1,68 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL-EXCEPT$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <qtest.h>
+#include <QListView>
+#include <QStandardItemModel>
+
+
+class tst_QListView : public QObject
+{
+    Q_OBJECT
+
+public:
+    tst_QListView() = default;
+    virtual ~tst_QListView() = default;
+
+private slots:
+    void benchSetCurrentIndex();
+};
+
+void tst_QListView::benchSetCurrentIndex()
+{
+    QStandardItemModel sm(50000, 1);
+    QListView lv;
+    lv.setModel(&sm);
+    const int rc = lv.model()->rowCount();
+    for (int i = 0; i < rc; i+= 100)
+        lv.setRowHidden(i, true);
+    lv.setCurrentIndex(lv.model()->index(0, 0, QModelIndex()));
+    lv.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&lv));
+
+    QBENCHMARK_ONCE {
+        while (lv.currentIndex().row() < rc - 20)
+            lv.setCurrentIndex(lv.model()->index(lv.currentIndex().row() + 17,
+                                                 lv.currentIndex().column(),
+                                                 QModelIndex()));
+    }
+}
+
+
+QTEST_MAIN(tst_QListView)
+#include "tst_qlistview.moc"
-- 
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