iOS: Propagate focus changes to VoiceOver

Changing the focus object should update the VoiceOver focused element,
the same way we do it on macOS.

There's no NSAccessibilityFocusedUIElementChangedNotification on iOS,
but we can pass the focused element as an argument when posting the
UIAccessibilityLayoutChangedNotification.

The class method on QMacAccessibilityElement to get an element for
an QAccessible::Id was not used by any callers, and has been modified
to resolve the container from the QAccessibleInterface, so that we
don't need to plumb that all the way from the focus change event.

Inspired-by: Jan Möller <jan.moeller@governikus.de>
Fixes: QTBUG-114608
Pick-to: 6.7 6.6 6.5
Change-Id: I2e43ae649bc7e3a44c1e1200e8de66bf420b1949
Reviewed-by: Lars Schmertmann <lars.schmertmann@governikus.de>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

5 files changed, 31 insertions, 5 deletions

diff --git a/src/plugins/platforms/ios/qiosplatformaccessibility.mm b/src/plugins/platforms/ios/qiosplatformaccessibility.mm
index f128ed6d67..eb18ee637e 100644
--- a/src/plugins/platforms/ios/qiosplatformaccessibility.mm
+++ b/src/plugins/platforms/ios/qiosplatformaccessibility.mm
@@ -9,6 +9,7 @@
 
 #include <QtGui/QtGui>
 #include "qioswindow.h"
+#include "quiaccessibilityelement.h"
 
 QIOSPlatformAccessibility::QIOSPlatformAccessibility()
 {}
@@ -42,6 +43,16 @@ void QIOSPlatformAccessibility::notifyAccessibilityUpdate(QAccessibleEvent *even
     if (!isActive() || !accessibleInterface)
         return;
     switch (event->type()) {
+    case QAccessible::Focus: {
+        auto *element = [QMacAccessibilityElement elementWithId:event->uniqueId()];
+        Q_ASSERT(element);
+        // There's no NSAccessibilityFocusedUIElementChangedNotification, like we have on
+        // macOS. Instead, the documentation for UIAccessibilityLayoutChangedNotification
+        // specifies that the optional argument to UIAccessibilityPostNotification is the
+        // accessibility element for VoiceOver to move to after processing the notification.
+        UIAccessibilityPostNotification(UIAccessibilityLayoutChangedNotification, element);
+        break;
+    }
     case QAccessible::ObjectCreated:
     case QAccessible::ObjectShow:
     case QAccessible::ObjectHide:
diff --git a/src/plugins/platforms/ios/qioswindow.h b/src/plugins/platforms/ios/qioswindow.h
index 1634213e06..02b2161202 100644
--- a/src/plugins/platforms/ios/qioswindow.h
+++ b/src/plugins/platforms/ios/qioswindow.h
@@ -63,6 +63,7 @@ public:
 #endif
 
     bool isForeignWindow() const override;
+    UIView *view() const;
 
 private:
     void applicationStateChanged(Qt::ApplicationState state);
diff --git a/src/plugins/platforms/ios/qioswindow.mm b/src/plugins/platforms/ios/qioswindow.mm
index 347c7b9df1..a0ba6213b9 100644
--- a/src/plugins/platforms/ios/qioswindow.mm
+++ b/src/plugins/platforms/ios/qioswindow.mm
@@ -458,6 +458,11 @@ bool QIOSWindow::isForeignWindow() const
     return ![m_view isKindOfClass:QUIView.class];
 }
 
+UIView *QIOSWindow::view() const
+{
+    return m_view;
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qioswindow.cpp"
diff --git a/src/plugins/platforms/ios/quiaccessibilityelement.h b/src/plugins/platforms/ios/quiaccessibilityelement.h
index e78fef6d30..8580325436 100644
--- a/src/plugins/platforms/ios/quiaccessibilityelement.h
+++ b/src/plugins/platforms/ios/quiaccessibilityelement.h
@@ -14,7 +14,7 @@
 @property (readonly) QAccessible::Id axid;
 
 - (instancetype)initWithId:(QAccessible::Id)anId withAccessibilityContainer:(id)view;
-+ (instancetype)elementWithId:(QAccessible::Id)anId withAccessibilityContainer:(id)view;
++ (instancetype)elementWithId:(QAccessible::Id)anId;
 
 @end
 
diff --git a/src/plugins/platforms/ios/quiaccessibilityelement.mm b/src/plugins/platforms/ios/quiaccessibilityelement.mm
index 08e366f32b..39b2cb8a50 100644
--- a/src/plugins/platforms/ios/quiaccessibilityelement.mm
+++ b/src/plugins/platforms/ios/quiaccessibilityelement.mm
@@ -8,6 +8,7 @@
 #include "private/qaccessiblecache_p.h"
 #include "private/qcore_mac_p.h"
 #include "uistrings_p.h"
+#include "qioswindow.h"
 
 QT_NAMESPACE_ALIAS_OBJC_CLASS(QMacAccessibilityElement);
 
@@ -23,7 +24,7 @@ QT_NAMESPACE_ALIAS_OBJC_CLASS(QMacAccessibilityElement);
     return self;
 }
 
-+ (instancetype)elementWithId:(QAccessible::Id)anId withAccessibilityContainer:(id)view
++ (instancetype)elementWithId:(QAccessible::Id)anId
 {
     Q_ASSERT(anId);
     if (!anId)
@@ -33,9 +34,17 @@ QT_NAMESPACE_ALIAS_OBJC_CLASS(QMacAccessibilityElement);
 
     QMacAccessibilityElement *element = cache->elementForId(anId);
     if (!element) {
-        Q_ASSERT(QAccessible::accessibleInterface(anId));
-        element = [[self alloc] initWithId:anId withAccessibilityContainer:view];
-        cache->insertElement(anId, element);
+        auto *a11yInterface = QAccessible::accessibleInterface(anId);
+        Q_ASSERT(a11yInterface);
+        auto *window = a11yInterface->window();
+        if (window && window->handle()) {
+            auto *platformWindow = static_cast<QIOSWindow*>(window->handle());
+            element = [[self alloc] initWithId:anId withAccessibilityContainer:platformWindow->view()];
+            cache->insertElement(anId, element);
+        } else {
+            qWarning() << "Could not create a11y element for" << window
+                << "with platform window" << (window ? window->handle() : nullptr);
+        }
     }
     return element;
 }