Android: Fix flashing on startup/shutdown

There were several issues on startup of the application which
were caused by the fact that we would get the wrong
available screen geometry on startup, set this as the
initial surface size and then expose native windows with this
size. This would cause first a flicker of white on the early
expose and the window contents to jump around as the window was
resized to the actual available space on screen.

The fix for this is to postpone the first expose until we have
actually got a proper screen size from the main layout. We use
width,height = 0 as an indicator that the available geometry
is not yet known, and we skip posting any expose events before
this is set by the layout.

In addition, since we removed the surface before we shut down
the application, it was by a white rectangle before the
shutdown transition happens, and this white rectangle will
be animated instead of application contents.

To rectify this, we make sure the last surface in the stack
remains in the layout until it is either replaced by a different
surface or until the application has shut down. This way, the
shutdown animation will work on this surface instead.

[ChangeLog][Android] Fixed regression where there would be flickering
on startup and shutdown of the application.

Task-number: QTBUG-38960
Change-Id: Ia1579ca8c522d8beeab066f78070ad49009d0238
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

4 files changed, 44 insertions, 6 deletions

diff --git a/src/plugins/platforms/android/androidjnimain.cpp b/src/plugins/platforms/android/androidjnimain.cpp
index 7ca4db710b..d484a2faff 100644
--- a/src/plugins/platforms/android/androidjnimain.cpp
+++ b/src/plugins/platforms/android/androidjnimain.cpp
@@ -573,8 +573,11 @@ static void updateWindow(JNIEnv */*env*/, jobject /*thiz*/)
         return;
 
     if (QGuiApplication::instance() != 0) {
-        foreach (QWindow *w, QGuiApplication::topLevelWindows())
-            QWindowSystemInterface::handleExposeEvent(w, QRegion(w->geometry()));
+        foreach (QWindow *w, QGuiApplication::topLevelWindows()) {
+            QRect availableGeometry = w->screen()->availableGeometry();
+            if (w->geometry().width() > 0 && w->geometry().height() > 0 && availableGeometry.width() > 0 && availableGeometry.height() > 0)
+                QWindowSystemInterface::handleExposeEvent(w, QRegion(w->geometry()));
+        }
     }
 
     QAndroidPlatformScreen *screen = static_cast<QAndroidPlatformScreen *>(m_androidPlatformIntegration->screen());
diff --git a/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp b/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp
index 34db729289..5a028e8a5b 100644
--- a/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp
+++ b/src/plugins/platforms/android/qandroidplatformopenglwindow.cpp
@@ -47,7 +47,8 @@
 #include <QSurfaceFormat>
 
 #include <qpa/qwindowsysteminterface.h>
-
+#include <qpa/qplatformscreen.h>
+#include <QtPlatformSupport/private/qeglconvenience_p.h>
 #include <android/native_window.h>
 #include <android/native_window_jni.h>
 
@@ -77,8 +78,20 @@ void QAndroidPlatformOpenGLWindow::setGeometry(const QRect &rect)
     if (rect == geometry())
         return;
 
+    QRect oldGeometry = geometry();
+
     QAndroidPlatformWindow::setGeometry(rect);
     QtAndroid::setSurfaceGeometry(m_nativeSurfaceId, rect);
+
+    QRect availableGeometry = screen()->availableGeometry();
+    if (oldGeometry.width() == 0
+            && oldGeometry.height() == 0
+            && rect.width() > 0
+            && rect.height() > 0
+            && availableGeometry.width() > 0
+            && availableGeometry.height() > 0) {
+        QWindowSystemInterface::handleExposeEvent(window(), QRegion(rect));
+    }
 }
 
 EGLSurface QAndroidPlatformOpenGLWindow::eglSurface(EGLConfig config)
@@ -100,8 +113,11 @@ void QAndroidPlatformOpenGLWindow::checkNativeSurface(EGLConfig config)
 
     createEgl(config);
 
+
     // we've create another surface, the window should be repainted
-    QWindowSystemInterface::handleExposeEvent(window(), QRegion(geometry()));
+    QRect availableGeometry = screen()->availableGeometry();
+    if (geometry().width() > 0 && geometry().height() > 0 && availableGeometry.width() > 0 && availableGeometry.height() > 0)
+        QWindowSystemInterface::handleExposeEvent(window(), QRegion(geometry()));
 }
 
 void QAndroidPlatformOpenGLWindow::createEgl(EGLConfig config)
@@ -143,7 +159,9 @@ void QAndroidPlatformOpenGLWindow::surfaceChanged(JNIEnv *jniEnv, jobject surfac
     unlockSurface();
 
     // repaint the window
-    QWindowSystemInterface::handleExposeEvent(window(), QRegion(geometry()));
+    QRect availableGeometry = screen()->availableGeometry();
+    if (geometry().width() > 0 && geometry().height() > 0 && availableGeometry.width() > 0 && availableGeometry.height() > 0)
+        QWindowSystemInterface::handleExposeEvent(window(), QRegion(geometry()));
 }
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/android/qandroidplatformscreen.cpp b/src/plugins/platforms/android/qandroidplatformscreen.cpp
index 678f4e6b5a..11472ce1da 100644
--- a/src/plugins/platforms/android/qandroidplatformscreen.cpp
+++ b/src/plugins/platforms/android/qandroidplatformscreen.cpp
@@ -55,6 +55,9 @@
 #include <android/bitmap.h>
 #include <android/native_window_jni.h>
 
+#include <QtGui/QGuiApplication>
+#include <QtGui/QWindow>
+
 QT_BEGIN_NAMESPACE
 
 #ifdef QANDROIDPLATFORMSCREEN_DEBUG
@@ -217,11 +220,23 @@ void QAndroidPlatformScreen::setGeometry(const QRect &rect)
     if (m_geometry == rect)
         return;
 
+    QRect oldGeometry = m_geometry;
+
     m_geometry = rect;
     QWindowSystemInterface::handleScreenGeometryChange(QPlatformScreen::screen(), geometry());
     QWindowSystemInterface::handleScreenAvailableGeometryChange(QPlatformScreen::screen(), availableGeometry());
     resizeMaximizedWindows();
 
+    if (oldGeometry.width() == 0 && oldGeometry.height() == 0 && rect.width() > 0 && rect.height() > 0) {
+        QList<QWindow *> windows = QGuiApplication::allWindows();
+        for (int i = 0; i < windows.size(); ++i) {
+            QWindow *w = windows.at(i);
+            QRect geometry = w->handle()->geometry();
+            if (geometry.width() > 0 && geometry.height() > 0)
+                QWindowSystemInterface::handleExposeEvent(w, QRegion(geometry));
+        }
+    }
+
     if (m_id != -1) {
         if (m_nativeSurface) {
             ANativeWindow_release(m_nativeSurface);
diff --git a/src/plugins/platforms/android/qandroidplatformwindow.cpp b/src/plugins/platforms/android/qandroidplatformwindow.cpp
index b4231f0283..558525b78c 100644
--- a/src/plugins/platforms/android/qandroidplatformwindow.cpp
+++ b/src/plugins/platforms/android/qandroidplatformwindow.cpp
@@ -88,7 +88,9 @@ void QAndroidPlatformWindow::setVisible(bool visible)
             setGeometry(platformScreen()->availableGeometry());
     }
 
-    QPlatformWindow::setVisible(visible);
+    QRect availableGeometry = screen()->availableGeometry();
+    if (geometry().width() > 0 && geometry().height() > 0 && availableGeometry.width() > 0 && availableGeometry.height() > 0)
+        QPlatformWindow::setVisible(visible);
 
     if (visible)
         platformScreen()->addWindow(this);