Android A11Y: handle valueChanged events

Before this patch Android A11Y implementation was missing
ValueChanged event handling. As a result, no update was given
when the element's value was changed.

Handling these events allows us to announce value changes on such
objects like Slider, SpinBox, etc...
This is a universal method of value-change announcement, so it
supports all sorts of A11Y gestures.

On the Java side a new function was introduced to announce the
values, because we need to use the actual element's *value*,
not its accessible name or description.

Task-number: QTBUG-93396
Pick-to: 6.3 6.2 5.15
Change-Id: Ic44abd5f01b9b6f5468962131466edaf6a49d498
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>
Reviewed-by: Rami Potinkara <rami.potinkara@qt.io>

src/android/jar/src/org/qtproject/qt/android/QtActivityDelegate.java

@@ -921,6 +921,13 @@ public class QtActivityDelegate
         m_accessibilityDelegate.notifyObjectFocus(viewId);
     }
 
+    public void notifyValueChanged(int viewId, String value)
+    {
+        if (m_accessibilityDelegate == null)
+            return;
+        m_accessibilityDelegate.notifyValueChanged(viewId, value);
+    }
+
     public void notifyQtAndroidPluginRunning(boolean running)
     {
         m_isPluginRunning = running;

src/android/jar/src/org/qtproject/qt/android/QtNative.java

@@ -998,6 +998,18 @@ public class QtNative
         });
     }
 
+    private static void notifyValueChanged(int viewId, String value)
+    {
+        runAction(new Runnable() {
+            @Override
+            public void run() {
+                if (m_activityDelegate != null) {
+                    m_activityDelegate.notifyValueChanged(viewId, value);
+                }
+            }
+        });
+    }
+
     public static void notifyQtAndroidPluginRunning(final boolean running)
     {
         m_activityDelegate.notifyQtAndroidPluginRunning(running);

src/android/jar/src/org/qtproject/qt/android/accessibility/QtAccessibilityDelegate.java

@@ -225,6 +225,41 @@ public class QtAccessibilityDelegate extends View.AccessibilityDelegate
                 AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUSED);
     }
 
+    public void notifyValueChanged(int viewId, String value)
+    {
+        // Send a TYPE_ANNOUNCEMENT event with the new value
+
+        if ((viewId == INVALID_ID) || !m_manager.isEnabled()) {
+            Log.w(TAG, "notifyValueChanged() for invalid view");
+            return;
+        }
+
+        final ViewGroup group = (ViewGroup)m_view.getParent();
+        if (group == null) {
+            Log.w(TAG, "Could not announce value because ViewGroup was null.");
+            return;
+        }
+
+        final AccessibilityEvent event =
+                AccessibilityEvent.obtain(AccessibilityEvent.TYPE_ANNOUNCEMENT);
+
+        event.setEnabled(true);
+        event.setClassName(m_view.getClass().getName() + DEFAULT_CLASS_NAME);
+
+        event.setContentDescription(value);
+
+        if (event.getText().isEmpty() && TextUtils.isEmpty(event.getContentDescription())) {
+            Log.w(TAG, "No value to announce for " + event.getClassName());
+            return;
+        }
+
+        event.setPackageName(m_view.getContext().getPackageName());
+        event.setSource(m_view, viewId);
+
+        if (!group.requestSendAccessibilityEvent(m_view, event))
+            Log.w(TAG, "Failed to send value change announcement for " + event.getClassName());
+    }
+
     public boolean sendEventForVirtualViewId(int virtualViewId, int eventType)
     {
         if ((virtualViewId == INVALID_ID) || !m_manager.isEnabled()) {

src/android/jar/src/org/qtproject/qt/android/accessibility/QtNativeAccessibility.java

@@ -55,4 +55,5 @@ class QtNativeAccessibility
     static native boolean scrollBackward(int objectId);
 
     static native boolean populateNode(int objectId, AccessibilityNodeInfo node);
+    static native String valueForAccessibleObject(int objectId);
 }

src/android/java/src/org/qtproject/qt/android/bindings/QtActivity.java

@@ -1148,6 +1148,11 @@ public class QtActivity extends Activity
         QtNative.activityDelegate().notifyObjectFocus(viewId);
     }
 
+    public void notifyValueChanged(int viewId, String value)
+    {
+        QtNative.activityDelegate().notifyValueChanged(viewId, value);
+    }
+
     public boolean isKeyboardVisible()
     {
         return QtNative.activityDelegate().isKeyboardVisible();

src/plugins/platforms/android/androidjniaccessibility.cpp

@@ -149,6 +149,14 @@ namespace QtAndroidAccessibility
         QtAndroid::notifyObjectFocus(accessibilityObjectId);
     }
 
+    static jstring jvalueForAccessibleObject(int objectId); // forward declaration
+
+    void notifyValueChanged(uint accessibilityObjectId)
+    {
+        jstring value = jvalueForAccessibleObject(accessibilityObjectId);
+        QtAndroid::notifyValueChanged(accessibilityObjectId, value);
+    }
+
     static QVarLengthArray<int, 8> childIdListForAccessibleObject_helper(int objectId)
     {
         QAccessibleInterface *iface = interfaceFromId(objectId);
@@ -345,6 +353,27 @@ if (!clazz) { \
 
         //__android_log_print(ANDROID_LOG_FATAL, m_qtTag, m_methodErrorMsg, METHOD_NAME, METHOD_SIGNATURE);
 
+    static QString textFromValue(QAccessibleInterface *iface)
+    {
+        QString valueStr;
+        QAccessibleValueInterface *valueIface = iface->valueInterface();
+        if (valueIface) {
+            // TODO: fix double-to-string conversion
+            valueStr = valueIface->currentValue().toString();
+        }
+        return valueStr;
+    }
+
+    static jstring jvalueForAccessibleObject(int objectId)
+    {
+        QAccessibleInterface *iface = interfaceFromId(objectId);
+        const QString value = textFromValue(iface);
+        QJniEnvironment env;
+        jstring jstr = env->NewString((jchar*)value.constData(), (jsize)value.size());
+        if (env.checkAndClearExceptions())
+            __android_log_print(ANDROID_LOG_WARN, m_qtTag, "Failed to create jstring");
+        return jstr;
+    }
 
     static QString descriptionForInterface(QAccessibleInterface *iface)
     {
@@ -356,9 +385,7 @@ if (!clazz) { \
             if (desc.isEmpty()) {
                 desc = iface->text(QAccessible::Value);
                 if (desc.isEmpty()) {
-                    if (QAccessibleValueInterface *valueIface = iface->valueInterface()) {
-                        desc= valueIface->currentValue().toString();
-                    }
+                    desc = textFromValue(iface);
                 }
             }
         }

src/plugins/platforms/android/androidjniaccessibility.h

@@ -54,6 +54,7 @@ namespace QtAndroidAccessibility
     void notifyLocationChange();
     void notifyObjectHide(uint accessibilityObjectId);
     void notifyObjectFocus(uint accessibilityObjectId);
+    void notifyValueChanged(uint accessibilityObjectId);
     void createAccessibilityContextObject(QObject *parent);
 }
 

src/plugins/platforms/android/androidjnimain.cpp

@@ -226,6 +226,12 @@ namespace QtAndroid
         QJniObject::callStaticMethod<void>(m_applicationClass, "notifyObjectFocus","(I)V", accessibilityObjectId);
     }
 
+    void notifyValueChanged(uint accessibilityObjectId, jstring value)
+    {
+        QJniObject::callStaticMethod<void>(m_applicationClass, "notifyValueChanged",
+                                           "(ILjava/lang/String;)V", accessibilityObjectId, value);
+    }
+
     void notifyQtAndroidPluginRunning(bool running)
     {
         QJniObject::callStaticMethod<void>(m_applicationClass, "notifyQtAndroidPluginRunning","(Z)V", running);

src/plugins/platforms/android/androidjnimain.h

@@ -103,6 +103,7 @@ namespace QtAndroid
     void notifyAccessibilityLocationChange();
     void notifyObjectHide(uint accessibilityObjectId, uint parentObjectId);
     void notifyObjectFocus(uint accessibilityObjectId);
+    void notifyValueChanged(uint accessibilityObjectId, jstring value);
     void notifyQtAndroidPluginRunning(bool running);
 
     const char *classErrorMsgFmt();

src/plugins/platforms/android/qandroidplatformaccessibility.cpp

@@ -66,6 +66,8 @@ void QAndroidPlatformAccessibility::notifyAccessibilityUpdate(QAccessibleEvent *
         QtAndroidAccessibility::notifyObjectHide(event->uniqueId());
     } else if (event->type() == QAccessible::Focus) {
         QtAndroidAccessibility::notifyObjectFocus(event->uniqueId());
+    } else if (event->type() == QAccessible::ValueChanged) {
+        QtAndroidAccessibility::notifyValueChanged(event->uniqueId());
     }
 }