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, 15 insertions, 1 deletions

diff --git a/tests/auto/accessibility/tst_accessibility.cpp b/tests/auto/accessibility/tst_accessibility.cpp
index 614566e6..7e491b54 100644
--- a/tests/auto/accessibility/tst_accessibility.cpp
+++ b/tests/auto/accessibility/tst_accessibility.cpp
@@ -43,6 +43,9 @@
 #include "../shared/util.h"
 
 #if QT_CONFIG(accessibility)
+#include <QtGui/private/qguiapplication_p.h>
+#include <QtGui/qpa/qplatformintegration.h>
+#include <QtGui/qpa/qplatformaccessibility.h>
 #include <QtQuick/private/qquickaccessibleattached_p.h>
 #endif
 
@@ -113,6 +116,14 @@ void tst_accessibility::a11y_data()
     QTest::newRow("WeekNumberColumn") << "weeknumbercolumn" << 0x0 << "WeekNumberColumn"; //QAccessible::NoRole
 }
 
+#if QT_CONFIG(accessibility)
+static QPlatformAccessibility *platformAccessibility()
+{
+    QPlatformIntegration *pfIntegration = QGuiApplicationPrivate::platformIntegration();
+    return pfIntegration ? pfIntegration->accessibility() : nullptr;
+}
+#endif
+
 void tst_accessibility::a11y()
 {
     QFETCH(QString, name);
@@ -150,7 +161,10 @@ void tst_accessibility::a11y()
             QVERIFY(acc);
         } else {
             QVERIFY(!acc);
-            QAccessible::setActive(true);
+            QPlatformAccessibility *accessibility = platformAccessibility();
+            if (!accessibility)
+                QSKIP("No QPlatformAccessibility available.");
+            accessibility->setActive(true);
             acc = QQuickAccessibleAttached::attachedProperties(item);
         }
     }