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>

src/plugins/platforms/android/androidjnimain.cpp

@@ -418,6 +418,9 @@ namespace QtAndroid
             return;
 
         m_surfaces.remove(surfaceId);
+        if (m_surfaces.isEmpty())
+            m_surfaceId = 1;
+
         QJNIEnvironmentPrivate env;
         if (!env)
             return;

src/plugins/platforms/android/qandroidplatformopenglcontext.cpp

@@ -58,10 +58,10 @@ QAndroidPlatformOpenGLContext::QAndroidPlatformOpenGLContext(const QSurfaceForma
 
 void QAndroidPlatformOpenGLContext::swapBuffers(QPlatformSurface *surface)
 {
-    QEGLPlatformContext::swapBuffers(surface);
-
     if (surface->surface()->surfaceClass() == QSurface::Window)
         static_cast<QAndroidPlatformOpenGLWindow *>(surface)->checkNativeSurface(eglConfig());
+
+    QEGLPlatformContext::swapBuffers(surface);
 }
 
 bool QAndroidPlatformOpenGLContext::needsFBOReadBackWorkaroud()

src/plugins/platforms/android/qandroidplatformopenglwindow.cpp

@@ -57,10 +57,6 @@ QT_BEGIN_NAMESPACE
 QAndroidPlatformOpenGLWindow::QAndroidPlatformOpenGLWindow(QWindow *window, EGLDisplay display)
     :QAndroidPlatformWindow(window), m_eglDisplay(display)
 {
-    lockSurface();
-    m_nativeSurfaceId = QtAndroid::createSurface(this, geometry(), bool(window->flags() & Qt::WindowStaysOnTopHint), 32);
-    m_surfaceWaitCondition.wait(&m_surfaceMutex);
-    unlockSurface();
 }
 
 QAndroidPlatformOpenGLWindow::~QAndroidPlatformOpenGLWindow()
@@ -97,6 +93,13 @@ void QAndroidPlatformOpenGLWindow::setGeometry(const QRect &rect)
 EGLSurface QAndroidPlatformOpenGLWindow::eglSurface(EGLConfig config)
 {
     QMutexLocker lock(&m_surfaceMutex);
+
+    if (m_nativeSurfaceId == -1) {
+        const bool windowStaysOnTop = bool(window()->flags() & Qt::WindowStaysOnTopHint);
+        m_nativeSurfaceId = QtAndroid::createSurface(this, geometry(), windowStaysOnTop, 32);
+        m_surfaceWaitCondition.wait(&m_surfaceMutex);
+    }
+
     if (m_eglSurface == EGL_NO_SURFACE) {
         m_surfaceMutex.unlock();
         checkNativeSurface(config);
@@ -120,6 +123,20 @@ void QAndroidPlatformOpenGLWindow::checkNativeSurface(EGLConfig config)
         QWindowSystemInterface::handleExposeEvent(window(), QRegion(geometry()));
 }
 
+void QAndroidPlatformOpenGLWindow::applicationStateChanged(Qt::ApplicationState state)
+{
+    QAndroidPlatformWindow::applicationStateChanged(state);
+    if (state <=  Qt::ApplicationHidden && QtAndroid::blockEventLoopsWhenSuspended()) {
+        lockSurface();
+        if (m_nativeSurfaceId != -1) {
+            QtAndroid::destroySurface(m_nativeSurfaceId);
+            m_nativeSurfaceId = -1;
+        }
+        clearEgl();
+        unlockSurface();
+    }
+}
+
 void QAndroidPlatformOpenGLWindow::createEgl(EGLConfig config)
 {
     clearEgl();

src/plugins/platforms/android/qandroidplatformopenglwindow.h

@@ -64,6 +64,8 @@ public:
 
     void checkNativeSurface(EGLConfig config);
 
+    void applicationStateChanged(Qt::ApplicationState);
+
 protected:
     virtual void surfaceChanged(JNIEnv *jniEnv, jobject surface, int w, int h);
     void createEgl(EGLConfig config);

src/plugins/platforms/android/qandroidplatformscreen.cpp

@@ -54,6 +54,7 @@
 
 #include <android/bitmap.h>
 #include <android/native_window_jni.h>
+#include <qguiapplication.h>
 
 #include <QtGui/QGuiApplication>
 #include <QtGui/QWindow>
@@ -102,6 +103,7 @@ QAndroidPlatformScreen::QAndroidPlatformScreen():QObject(),QPlatformScreen()
     m_redrawTimer.setSingleShot(true);
     m_redrawTimer.setInterval(0);
     connect(&m_redrawTimer, SIGNAL(timeout()), this, SLOT(doRedraw()));
+    connect(qGuiApp, &QGuiApplication::applicationStateChanged, this, &QAndroidPlatformScreen::applicationStateChanged);
 }
 
 QAndroidPlatformScreen::~QAndroidPlatformScreen()
@@ -109,8 +111,7 @@ QAndroidPlatformScreen::~QAndroidPlatformScreen()
     if (m_id != -1) {
         QtAndroid::destroySurface(m_id);
         m_surfaceWaitCondition.wakeOne();
-        if (m_nativeSurface)
-            ANativeWindow_release(m_nativeSurface);
+        releaseSurface();
     }
 }
 
@@ -133,7 +134,7 @@ QWindow *QAndroidPlatformScreen::topLevelAt(const QPoint &p) const
 
 void QAndroidPlatformScreen::addWindow(QAndroidPlatformWindow *window)
 {
-    if (window->parent())
+    if (window->parent() && window->isRaster())
         return;
 
     m_windowStack.prepend(window);
@@ -149,10 +150,11 @@ void QAndroidPlatformScreen::addWindow(QAndroidPlatformWindow *window)
 
 void QAndroidPlatformScreen::removeWindow(QAndroidPlatformWindow *window)
 {
-    if (window->parent())
+    if (window->parent() && window->isRaster())
         return;
 
     m_windowStack.removeOne(window);
+
     if (window->isRaster()) {
         m_rasterSurfaces.deref();
         setDirty(window->geometry());
@@ -165,7 +167,7 @@ void QAndroidPlatformScreen::removeWindow(QAndroidPlatformWindow *window)
 
 void QAndroidPlatformScreen::raise(QAndroidPlatformWindow *window)
 {
-    if (window->parent())
+    if (window->parent() && window->isRaster())
         return;
 
     int index = m_windowStack.indexOf(window);
@@ -182,7 +184,7 @@ void QAndroidPlatformScreen::raise(QAndroidPlatformWindow *window)
 
 void QAndroidPlatformScreen::lower(QAndroidPlatformWindow *window)
 {
-    if (window->parent())
+    if (window->parent() && window->isRaster())
         return;
 
     int index = m_windowStack.indexOf(window);
@@ -247,14 +249,25 @@ void QAndroidPlatformScreen::setAvailableGeometry(const QRect &rect)
     }
 
     if (m_id != -1) {
-        if (m_nativeSurface) {
-            ANativeWindow_release(m_nativeSurface);
-            m_nativeSurface = 0;
-        }
+        releaseSurface();
         QtAndroid::setSurfaceGeometry(m_id, rect);
     }
 }
 
+void QAndroidPlatformScreen::applicationStateChanged(Qt::ApplicationState state)
+{
+    foreach (QAndroidPlatformWindow *w, m_windowStack)
+        w->applicationStateChanged(state);
+
+    if (state <=  Qt::ApplicationHidden && QtAndroid::blockEventLoopsWhenSuspended()) {
+        lockSurface();
+        QtAndroid::destroySurface(m_id);
+        m_id = -1;
+        releaseSurface();
+        unlockSurface();
+    }
+}
+
 void QAndroidPlatformScreen::topWindowChanged(QWindow *w)
 {
     QtAndroidMenu::setActiveTopLevelWindow(w);
@@ -365,18 +378,22 @@ void QAndroidPlatformScreen::surfaceChanged(JNIEnv *env, jobject surface, int w,
 {
     lockSurface();
     if (surface && w && h) {
-        if (m_nativeSurface)
-            ANativeWindow_release(m_nativeSurface);
+        releaseSurface();
         m_nativeSurface = ANativeWindow_fromSurface(env, surface);
         QMetaObject::invokeMethod(this, "setDirty", Qt::QueuedConnection, Q_ARG(QRect, QRect(0, 0, w, h)));
     } else {
-        if (m_nativeSurface) {
-            ANativeWindow_release(m_nativeSurface);
-            m_nativeSurface = 0;
-        }
+        releaseSurface();
     }
     unlockSurface();
     m_surfaceWaitCondition.wakeOne();
 }
 
+void QAndroidPlatformScreen::releaseSurface()
+{
+    if (m_nativeSurface) {
+        ANativeWindow_release(m_nativeSurface);
+        m_nativeSurface = 0;
+    }
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/android/qandroidplatformscreen.h

@@ -107,6 +107,8 @@ private:
     Qt::ScreenOrientation orientation() const;
     Qt::ScreenOrientation nativeOrientation() const;
     void surfaceChanged(JNIEnv *env, jobject surface, int w, int h);
+    void releaseSurface();
+    void applicationStateChanged(Qt::ApplicationState);
 
 private slots:
     void doRedraw();

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

src/plugins/platforms/android/qandroidplatformwindow.h

@@ -72,7 +72,9 @@ public:
     void requestActivateWindow();
     void updateStatusBarVisibility();
     inline bool isRaster() const { return window()->surfaceType() == QSurface::RasterSurface; }
+    bool isExposed() const;
 
+    virtual void applicationStateChanged(Qt::ApplicationState);
 protected:
     void setGeometry(const QRect &rect);