Android: Fix crash when setting WA_NativeWindow

We don't support native widgets in Android, so we can get into a mess
when people set this widget attribute, since the FB compositor
will assume that all widgets have their own backing store. This adds
a capability flag to the QPlatformIntegration which allows the plugin
to disable the WA_NativeWindow feature.

Task-number: QTBUG-32685
Change-Id: Ic200487da4a297f71ab594cf7c90d1e1d53bacd3
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

src/gui/kernel/qplatformintegration.cpp

@@ -237,7 +237,7 @@ QPlatformServices *QPlatformIntegration::services() const
 
 bool QPlatformIntegration::hasCapability(Capability cap) const
 {
-    return cap == NonFullScreenWindows;
+    return cap == NonFullScreenWindows || cap == NativeWidgets;
 }
 
 QPlatformPixmap *QPlatformIntegration::createPlatformPixmap(QPlatformPixmap::PixelType type) const

src/gui/kernel/qplatformintegration.h

@@ -91,7 +91,8 @@ public:
         MultipleWindows,
         ApplicationState,
         ForeignWindows,
-        NonFullScreenWindows
+        NonFullScreenWindows,
+        NativeWidgets
     };
 
     virtual ~QPlatformIntegration() { }

src/plugins/platforms/android/src/qandroidplatformintegration.cpp

@@ -118,6 +118,7 @@ bool QAndroidPlatformIntegration::hasCapability(Capability cap) const
     switch (cap) {
         case ThreadedPixmaps: return true;
         case NonFullScreenWindows: return false;
+        case NativeWidgets: return false;
         default:
 #ifndef ANDROID_PLUGIN_OPENGL
         return QPlatformIntegration::hasCapability(cap);

src/widgets/kernel/qwidget.cpp

@@ -10039,6 +10039,13 @@ void QWidget::setAttribute(Qt::WidgetAttribute attribute, bool on)
     }
 #endif
 
+    // Don't set WA_NativeWindow on platforms that don't support it
+    if (attribute == Qt::WA_NativeWindow) {
+        QPlatformIntegration *platformIntegration = QGuiApplicationPrivate::platformIntegration();
+        if (!platformIntegration->hasCapability(QPlatformIntegration::NativeWidgets))
+            return;
+    }
+
     setAttribute_internal(attribute, on, data, d);
 
     switch (attribute) {