Android: Release all windows when the application is suspended.

When an application is suspended on Android all its Gl surfaces
are destroyed and can't be used to render anymore, so we should
release them in order to give back to the system the memory used
by them.

[ChangeLog] [Android] Release all windows when the application is
suspended.

Task-number: QTBUG-29069
Change-Id: I038aaa2006da1f3188fccba943ec4ffb3e551cf0
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/plugins/platforms/android/qandroidplatformwindow.cpp b/src/plugins/platforms/android/qandroidplatformwindow.cpp
index 558525b78c..d07573fb88 100644
--- a/src/plugins/platforms/android/qandroidplatformwindow.cpp
+++ b/src/plugins/platforms/android/qandroidplatformwindow.cpp
@@ -45,6 +45,8 @@
 #include "qandroidplatformscreen.h"
 
 #include "androidjnimain.h"
+
+#include <qguiapplication.h>
 #include <qpa/qwindowsysteminterface.h>
 
 QT_BEGIN_NAMESPACE
@@ -160,5 +162,21 @@ void QAndroidPlatformWindow::updateStatusBarVisibility()
     }
 }
 
+bool QAndroidPlatformWindow::isExposed() const
+{
+    return qApp->applicationState() > Qt::ApplicationHidden
+            && window()->isVisible()
+            && !window()->geometry().isEmpty();
+}
+
+void QAndroidPlatformWindow::applicationStateChanged(Qt::ApplicationState)
+{
+    QRegion region;
+    if (isExposed())
+        region = QRect(QPoint(), geometry().size());
+
+    QWindowSystemInterface::handleExposeEvent(window(), region);
+    QWindowSystemInterface::flushWindowSystemEvents();
+}
 
 QT_END_NAMESPACE