Accepting request 929783 from KDE:Qt6

- Add patch for critical performance regression in qscrollarea
  * 0001-qscrollarea-performance-fix.patch (forwarded request 929782 from cgiboudeaux)

OBS-URL: https://build.opensuse.org/request/show/929783
OBS-URL: https://build.opensuse.org/package/show/openSUSE:Factory/qt6-base?expand=0&rev=12

0001-qscrollarea-performance-fix.patch

@@ -0,0 +1,55 @@
+From ffc9323671d045e3566980d9ed4567f071004e65 Mon Sep 17 00:00:00 2001
+From: Volker Hilsheimer <volker.hilsheimer@qt.io>
+Date: Thu, 28 Oct 2021 16:55:33 +0200
+Subject: Fix performance regression when avoiding scrollbar flipping
+
+Amends 6c4dc722cb9bf765904feefff4fb00bdb0b3dc9f.
+
+Don't search for the optimal size of the scrollarea's widget if it can't
+be found anyway. Try the size with scrollbar first, which covers the
+vast majority of sizes.
+
+Optimizing the loop with e.g. a binary search adds no value, as the size
+is often just a pixel too small.
+
+Since we can't rely on the number of height-for-width calls, we can't
+meaningfully test this behavior. The number of calls is still very high
+during showing and resizing; optimizing this further is for a separate
+commit.
+
+Fixes: QTBUG-97811
+Pick-to: 6.2 5.15
+Change-Id: If145302e6414b32cf1ce7251ff33b0039f584867
+Reviewed-by: Jonas Kvinge <jonas@jkvinge.net>
+Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>
+---
+ src/widgets/widgets/qscrollarea.cpp | 11 +++++++----
+ 1 file changed, 7 insertions(+), 4 deletions(-)
+
+(limited to 'src/widgets/widgets/qscrollarea.cpp')
+
+diff --git a/src/widgets/widgets/qscrollarea.cpp b/src/widgets/widgets/qscrollarea.cpp
+index f880240ea7..e8fdadb648 100644
+--- a/src/widgets/widgets/qscrollarea.cpp
++++ b/src/widgets/widgets/qscrollarea.cpp
+@@ -203,10 +203,13 @@ void QScrollAreaPrivate::updateScrollBars()
+             if (vbarpolicy == Qt::ScrollBarAsNeeded) {
+                 int vbarWidth = vbar->sizeHint().width();
+                 QSize m_hfw = m.expandedTo(min).boundedTo(max);
+-                while (h > m.height() && vbarWidth) {
+-                    --vbarWidth;
+-                    --m_hfw.rwidth();
+-                    h = widget->heightForWidth(m_hfw.width());
++                // is there any point in searching?
++                if (widget->heightForWidth(m_hfw.width() - vbarWidth) <= m.height()) {
++                    while (h > m.height() && vbarWidth) {
++                        --vbarWidth;
++                        --m_hfw.rwidth();
++                        h = widget->heightForWidth(m_hfw.width());
++                    }
+                 }
+                 max = QSize(m_hfw.width(), qMax(m_hfw.height(), h));
+             }
+-- 
+cgit v1.2.1
+

qt6-base.changes

@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Thu Nov  4 20:59:52 UTC 2021 - Jonas Kvinge <jonaski@opensuse.org>
+
+- Add patch for critical performance regression in qscrollarea
+  * 0001-qscrollarea-performance-fix.patch
+
 -------------------------------------------------------------------
 Tue Oct 26 11:22:28 UTC 2021 - Christophe Giboudeaux <christophe@krop.fr>
 

qt6-base.spec

@@ -44,6 +44,7 @@ Patch100:       0001-Tell-the-truth-about-private-API.patch
 %if 0%{?suse_version} == 1500
 Patch101:       0001-Require-GCC-10.patch
 %endif
+Patch102:       0001-qscrollarea-performance-fix.patch
 ##
 BuildRequires:  cmake >= 3.18.3
 BuildRequires:  cups-devel