Fix hellowindow example generating excess timers

The example was creating a new timer on every expose event, which
quickly leads into massive excess of timeout signals.

Fixed by only creating one timer.

Task-number: QTBUG-27836
Change-Id: Ia6ed1bd9575e296f4c6c5b12509095e4d5c016dd
Reviewed-by: Jonathan Liu <net147@gmail.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

diff --git a/examples/opengl/hellowindow/hellowindow.cpp b/examples/opengl/hellowindow/hellowindow.cpp
index 3c314d9..7770949 100644 (file)
--- a/examples/opengl/hellowindow/hellowindow.cpp
+++ b/examples/opengl/hellowindow/hellowindow.cpp
@@ -60,8 +60,7 @@ Renderer::Renderer(const QSurfaceFormat &format, Renderer *share, QScreen *scree
 }
 
 HelloWindow::HelloWindow(const QSharedPointer<Renderer> &renderer)
-    : m_colorIndex(0)
-    , m_renderer(renderer)
+    : m_colorIndex(0), m_renderer(renderer), m_timer(0)
 {
     setSurfaceType(QWindow::OpenGLSurface);
     setWindowFlags(Qt::Window | Qt::WindowSystemMenuHint | Qt::WindowTitleHint | Qt::WindowMinMaxButtonsHint | Qt::WindowCloseButtonHint);
@@ -84,9 +83,11 @@ void HelloWindow::exposeEvent(QExposeEvent *event)
 
     render();
 
-    QTimer *timer = new QTimer(this);
-    connect(timer, SIGNAL(timeout()), this, SLOT(render()));
-    timer->start(10);
+    if (!m_timer) {
+        m_timer = new QTimer(this);
+        connect(m_timer, SIGNAL(timeout()), this, SLOT(render()));
+        m_timer->start(10);
+    }
 }
 
 void HelloWindow::mousePressEvent(QMouseEvent *)

diff --git a/examples/opengl/hellowindow/hellowindow.h b/examples/opengl/hellowindow/hellowindow.h
index a3e9fc5..adb85c1 100644 (file)
--- a/examples/opengl/hellowindow/hellowindow.h
+++ b/examples/opengl/hellowindow/hellowindow.h
@@ -49,6 +49,7 @@
 
 QT_BEGIN_NAMESPACE
 class QOpenGLContext;
+class QTimer;
 QT_END_NAMESPACE
 
 class Renderer : public QObject
@@ -107,4 +108,5 @@ private:
     int m_colorIndex;
     QColor m_color;
     const QSharedPointer<Renderer> m_renderer;
+    QTimer *m_timer;
 };