Fix accessibility-related performance regressions

Before 089dd16f, we had a QQuickControlPrivate::accessibleAttached
member that indicated whether accessibility was active. Since 4be38ab
in qtdeclarative, it was possible to access QQuickAccessibleAttached::
attachedProperties() directly, but we ended up accidentally accessing
it even when accessibility was not active, which added noticeable
overhead.

This improves those qmlbench test cases that call accessibility-aware
setters such as QQuickAbstractButton::setChecked() a lot. For example,
the test cases for CheckBox and RadioButton create large amounts of
controls with a "checked: index % 2" binding.

- CheckBox: 84 => 93 frames
- RadioButton: 98 => 113 frames

QAccessible::setActive(true) only notifies the observers, but does not
really make accessibility active in the sense that the consequent calls
to QAccessible::isActive() still return false. tst_accessible had to be
changed to use QPlatformAccessible::setActive() instead.

Change-Id: I8fd0fe2dddfd5633ce22a080bcda459f2d6e443e
Reviewed-by: Liang Qi <liang.qi@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/quicktemplates2/qquicklabel.cpp b/src/quicktemplates2/qquicklabel.cpp
index 8d964745..115a64c6 100644
--- a/src/quicktemplates2/qquicklabel.cpp
+++ b/src/quicktemplates2/qquicklabel.cpp
@@ -176,7 +176,7 @@ void QQuickLabelPrivate::textChanged(const QString &text)
 {
 #if QT_CONFIG(accessibility)
     Q_Q(QQuickLabel);
-    if (QQuickAccessibleAttached *accessibleAttached = QQuickAccessibleAttached::attachedProperties(q))
+    if (QQuickAccessibleAttached *accessibleAttached = QQuickControlPrivate::accessibleAttached(q))
         accessibleAttached->setName(text);
 #else
     Q_UNUSED(text)