9 files changed, 24 insertions, 31 deletions
diff --git a/examples/opengl/2dpainting/glwidget.cpp b/examples/opengl/2dpainting/glwidget.cpp
index 23065a0b42..e1e40ea84c 100644
--- a/examples/opengl/2dpainting/glwidget.cpp
+++ b/examples/opengl/2dpainting/glwidget.cpp
@@ -38,10 +38,11 @@
 **
 ****************************************************************************/
 
-#include <QtWidgets>
 #include "glwidget.h"
 #include "helper.h"
 
+#include <QTimer>
+
 //! [0]
 GLWidget::GLWidget(Helper *helper, QWidget *parent)
     : QGLWidget(QGLFormat(QGL::SampleBuffers), parent), helper(helper)
diff --git a/examples/opengl/2dpainting/glwidget.h b/examples/opengl/2dpainting/glwidget.h
index f8e44f8a3e..3540810983 100644
--- a/examples/opengl/2dpainting/glwidget.h
+++ b/examples/opengl/2dpainting/glwidget.h
@@ -45,10 +45,6 @@
 
 //! [0]
 class Helper;
-QT_BEGIN_NAMESPACE
-class QPaintEvent;
-class QWidget;
-QT_END_NAMESPACE
 
 class GLWidget : public QGLWidget
 {
diff --git a/examples/opengl/2dpainting/helper.cpp b/examples/opengl/2dpainting/helper.cpp
index b412dc11dc..168df2aff3 100644
--- a/examples/opengl/2dpainting/helper.cpp
+++ b/examples/opengl/2dpainting/helper.cpp
@@ -38,9 +38,12 @@
 **
 ****************************************************************************/
 
-#include <QtWidgets>
 #include "helper.h"
 
+#include <QPainter>
+#include <QPaintEvent>
+#include <QWidget>
+
 //! [0]
 Helper::Helper()
 {
@@ -70,14 +73,15 @@ void Helper::paint(QPainter *painter, QPaintEvent *event, int elapsed)
     painter->setPen(circlePen);
     painter->rotate(elapsed * 0.030);
 
-    qreal r = elapsed/1000.0;
+    qreal r = elapsed / 1000.0;
     int n = 30;
     for (int i = 0; i < n; ++i) {
         painter->rotate(30);
-        qreal radius = 0 + 120.0*((i+r)/n);
-        qreal circleRadius = 1 + ((i+r)/n)*20;
+        qreal factor = (i + r) / n;
+        qreal radius = 0 + 120.0 * factor;
+        qreal circleRadius = 1 + factor * 20;
         painter->drawEllipse(QRectF(radius, -circleRadius,
-                                    circleRadius*2, circleRadius*2));
+                                    circleRadius * 2, circleRadius * 2));
     }
     painter->restore();
 //! [2]
@@ -85,6 +89,6 @@ void Helper::paint(QPainter *painter, QPaintEvent *event, int elapsed)
 //! [3]
     painter->setPen(textPen);
     painter->setFont(textFont);
-    painter->drawText(QRect(-50, -50, 100, 100), Qt::AlignCenter, "Qt");
+    painter->drawText(QRect(-50, -50, 100, 100), Qt::AlignCenter, QStringLiteral("Qt"));
 }
 //! [3]
diff --git a/examples/opengl/2dpainting/helper.h b/examples/opengl/2dpainting/helper.h
index 10bb2a5a9c..47f4c96639 100644
--- a/examples/opengl/2dpainting/helper.h
+++ b/examples/opengl/2dpainting/helper.h
@@ -44,11 +44,7 @@
 #include <QBrush>
 #include <QFont>
 #include <QPen>
-
-QT_BEGIN_NAMESPACE
-class QPainter;
-class QPaintEvent;
-QT_END_NAMESPACE
+#include <QWidget>
 
 //! [0]
 class Helper
diff --git a/examples/opengl/2dpainting/main.cpp b/examples/opengl/2dpainting/main.cpp
index 3374e57964..903795685f 100644
--- a/examples/opengl/2dpainting/main.cpp
+++ b/examples/opengl/2dpainting/main.cpp
@@ -38,9 +38,10 @@
 **
 ****************************************************************************/
 
-#include <QApplication>
 #include "window.h"
 
+#include <QApplication>
+
 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
diff --git a/examples/opengl/2dpainting/widget.cpp b/examples/opengl/2dpainting/widget.cpp
index 49ce8b1329..832f37eb36 100644
--- a/examples/opengl/2dpainting/widget.cpp
+++ b/examples/opengl/2dpainting/widget.cpp
@@ -38,10 +38,11 @@
 **
 ****************************************************************************/
 
-#include <QtWidgets>
 #include "widget.h"
 #include "helper.h"
 
+#include <QPainter>
+#include <QTimer>
 
 //! [0]
 Widget::Widget(Helper *helper, QWidget *parent)
diff --git a/examples/opengl/2dpainting/widget.h b/examples/opengl/2dpainting/widget.h
index 7d665b3952..ccf424330c 100644
--- a/examples/opengl/2dpainting/widget.h
+++ b/examples/opengl/2dpainting/widget.h
@@ -45,9 +45,6 @@
 
 //! [0]
 class Helper;
-QT_BEGIN_NAMESPACE
-class QPaintEvent;
-QT_END_NAMESPACE
 
 class Widget : public QWidget
 {
diff --git a/examples/opengl/2dpainting/window.cpp b/examples/opengl/2dpainting/window.cpp
index 700d0caaa8..b6aba2a945 100644
--- a/examples/opengl/2dpainting/window.cpp
+++ b/examples/opengl/2dpainting/window.cpp
@@ -38,15 +38,19 @@
 **
 ****************************************************************************/
 
-#include <QtWidgets>
 #include "glwidget.h"
 #include "widget.h"
 #include "window.h"
 
+#include <QGridLayout>
+#include <QLabel>
+#include <QTimer>
+
 //! [0]
 Window::Window()
-    : QWidget()
 {
+    setWindowTitle(tr("2D Painting on Native and OpenGL Widgets"));
+
     Widget *native = new Widget(&helper, this);
     GLWidget *openGL = new GLWidget(&helper, this);
     QLabel *nativeLabel = new QLabel(tr("Native"));
@@ -65,7 +69,5 @@ Window::Window()
     connect(timer, SIGNAL(timeout()), native, SLOT(animate()));
     connect(timer, SIGNAL(timeout()), openGL, SLOT(animate()));
     timer->start(50);
-
-    setWindowTitle(tr("2D Painting on Native and OpenGL Widgets"));
 }
 //! [0]
diff --git a/examples/opengl/2dpainting/window.h b/examples/opengl/2dpainting/window.h
index 263572637e..acded9895f 100644
--- a/examples/opengl/2dpainting/window.h
+++ b/examples/opengl/2dpainting/window.h
@@ -41,14 +41,9 @@
 #ifndef WINDOW_H
 #define WINDOW_H
 
-#include <QWidget>
-
 #include "helper.h"
 
-QT_BEGIN_NAMESPACE
-class QLabel;
-class QWidget;
-QT_END_NAMESPACE
+#include <QWidget>
 
 //! [0]
 class Window : public QWidget