QML Preview: Add a frames per second counter

It is instructive to the client to know how many frames per second the
current QML can achieve in the preview.

Change-Id: I8b73e2b5218410d903a07dfe27c038663c84fdee
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 18 insertions, 0 deletions

diff --git a/tests/auto/qml/debugger/qqmlpreview/tst_qqmlpreview.cpp b/tests/auto/qml/debugger/qqmlpreview/tst_qqmlpreview.cpp
index 152a4a7f9f..9477603654 100644
--- a/tests/auto/qml/debugger/qqmlpreview/tst_qqmlpreview.cpp
+++ b/tests/auto/qml/debugger/qqmlpreview/tst_qqmlpreview.cpp
@@ -57,6 +57,7 @@ private:
     QStringList m_filesNotFound;
     QStringList m_directories;
     QStringList m_serviceErrors;
+    quint16 m_frames = 0;
 
 private slots:
     void cleanup() final;
@@ -67,6 +68,7 @@ private slots:
     void blacklist();
     void error();
     void zoom();
+    void fps();
 };
 
 QQmlDebugTest::ConnectResult tst_QQmlPreview::startQmlProcess(const QString &qmlFile)
@@ -102,6 +104,9 @@ QList<QQmlDebugClient *> tst_QQmlPreview::createClients()
     QObject::connect(m_client, &QQmlPreviewClient::error, this, [this](const QString &error) {
         m_serviceErrors.append(error);
     });
+    QObject::connect(m_client, &QQmlPreviewClient::fps, this, [this](quint16 frames) {
+        m_frames += frames;
+    });
 
     return QList<QQmlDebugClient *>({m_client});
 }
@@ -135,6 +140,7 @@ void tst_QQmlPreview::cleanup()
     m_files.clear();
     m_filesNotFound.clear();
     m_serviceErrors.clear();
+    m_frames = 0;
 }
 
 void tst_QQmlPreview::connect()
@@ -323,6 +329,18 @@ void tst_QQmlPreview::zoom()
     QVERIFY(m_serviceErrors.isEmpty());
 }
 
+void tst_QQmlPreview::fps()
+{
+    const QString file("qtquick2.qml");
+    QCOMPARE(startQmlProcess(file), ConnectSuccess);
+    QVERIFY(m_client);
+    m_client->triggerLoad(testFileUrl(file));
+    if (QGuiApplication::platformName() != "offscreen")
+        QTRY_VERIFY(m_frames > 100);
+    else
+        QSKIP("offscreen rendering doesn't produce any frames");
+}
+
 QTEST_MAIN(tst_QQmlPreview)
 
 #include "tst_qqmlpreview.moc"