Fix accessibility info for tri-state checkboxes

The state information provided by QAccessibleInterface::state() was not
correctly reflecting the state of tri-state checkboxes: checkStateMixed
was never set. This change fixes this issue and also adds accessibility
update notifications for changes in checkStateMixed, which were missing.

Change-Id: Ia4a114559d5a957ca85bf2f169a6cece2c98d077
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

2 files changed, 16 insertions, 1 deletions

diff --git a/src/widgets/accessible/simplewidgets.cpp b/src/widgets/accessible/simplewidgets.cpp
index 73de51ff45..2fd664e13a 100644
--- a/src/widgets/accessible/simplewidgets.cpp
+++ b/src/widgets/accessible/simplewidgets.cpp
@@ -170,7 +170,7 @@ QAccessible::State QAccessibleButton::state() const
     if (b->isChecked())
         state.checked = true;
 #if QT_CONFIG(checkbox)
-    else if (cb && cb->checkState() == Qt::PartiallyChecked)
+    if (cb && cb->checkState() == Qt::PartiallyChecked)
         state.checkStateMixed = true;
 #endif
     if (b->isDown())
diff --git a/src/widgets/widgets/qcheckbox.cpp b/src/widgets/widgets/qcheckbox.cpp
index 9b49916774..235508535d 100644
--- a/src/widgets/widgets/qcheckbox.cpp
+++ b/src/widgets/widgets/qcheckbox.cpp
@@ -45,6 +45,9 @@
 #include "qstyle.h"
 #include "qstyleoption.h"
 #include "qevent.h"
+#ifndef QT_NO_ACCESSIBILITY
+#include "qaccessible.h"
+#endif
 
 #include "private/qabstractbutton_p.h"
 
@@ -243,6 +246,9 @@ Qt::CheckState QCheckBox::checkState() const
 void QCheckBox::setCheckState(Qt::CheckState state)
 {
     Q_D(QCheckBox);
+#ifndef QT_NO_ACCESSIBILITY
+    bool noChange = d->noChange;
+#endif
     if (state == Qt::PartiallyChecked) {
         d->tristate = true;
         d->noChange = true;
@@ -257,6 +263,15 @@ void QCheckBox::setCheckState(Qt::CheckState state)
         d->publishedState = state;
         emit stateChanged(state);
     }
+
+#ifndef QT_NO_ACCESSIBILITY
+    if (noChange != d->noChange) {
+        QAccessible::State s;
+        s.checkStateMixed = true;
+        QAccessibleStateChangeEvent event(this, s);
+        QAccessible::updateAccessibility(&event);
+    }
+#endif
 }