Widgets/GraphicsView examples: cleanup

Cleanup GraphicsView examples with the help of clang-tidy
 - modernize-use-nullptr
 - modernize-use-default-member-init
 - modernize-use-override.IgnoreDestructors
 - Some QList -> QVector changes
 - use nullptr
 - use normalized includes, remove unused includes
 - fix style

Change-Id: I79347e55bfde52f6ae7749cc7093fbd442044020
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

57 files changed, 283 insertions, 415 deletions

diff --git a/examples/widgets/graphicsview/anchorlayout/main.cpp b/examples/widgets/graphicsview/anchorlayout/main.cpp
index 59ced72018..98dacfb5fb 100644
--- a/examples/widgets/graphicsview/anchorlayout/main.cpp
+++ b/examples/widgets/graphicsview/anchorlayout/main.cpp
@@ -88,7 +88,7 @@ int main(int argc, char **argv)
     QGraphicsAnchorLayout *l = new QGraphicsAnchorLayout;
     l->setSpacing(0);
 
-    QGraphicsWidget *w = new QGraphicsWidget(0, Qt::Window);
+    QGraphicsWidget *w = new QGraphicsWidget(nullptr, Qt::Window);
     w->setPos(20, 20);
     w->setLayout(l);
 
diff --git a/examples/widgets/graphicsview/basicgraphicslayouts/layoutitem.cpp b/examples/widgets/graphicsview/basicgraphicslayouts/layoutitem.cpp
index 804db2f9be..2fbc232b20 100644
--- a/examples/widgets/graphicsview/basicgraphicslayouts/layoutitem.cpp
+++ b/examples/widgets/graphicsview/basicgraphicslayouts/layoutitem.cpp
@@ -51,33 +51,26 @@
 #include "layoutitem.h"
 
 #include <QGradient>
-#include <QGraphicsLinearLayout>
 #include <QPainter>
 
 //! [0]
-LayoutItem::LayoutItem(QGraphicsItem *parent/* = 0*/)
-    : QGraphicsLayoutItem(), QGraphicsItem(parent)
+LayoutItem::LayoutItem(QGraphicsItem *parent)
+    : QGraphicsLayoutItem(), QGraphicsItem(parent),
+      m_pix(QPixmap(QLatin1String(":/images/block.png")))
 {
-    m_pix = new QPixmap(QLatin1String(":/images/block.png"));
     setGraphicsItem(this);
 }
 //! [0]
 
-LayoutItem::~LayoutItem()
-{
-    delete m_pix;
-}
-
 //! [1]
-void LayoutItem::paint(QPainter *painter,
-    const QStyleOptionGraphicsItem *option, QWidget *widget /*= 0*/)
+void LayoutItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
+                       QWidget *widget)
 {
     Q_UNUSED(widget);
     Q_UNUSED(option);
 
-    QRectF frame(QPointF(0,0), geometry().size());
-    qreal w = m_pix->width();
-    qreal h = m_pix->height();
+    QRectF frame(QPointF(0, 0), geometry().size());
+    const QSize pmSize = m_pix.size();
     QGradientStops stops;
 //! [1]
 
@@ -94,8 +87,8 @@ void LayoutItem::paint(QPainter *painter,
     painter->drawRoundedRect(frame, 10.0, 10.0);
 
     // paint a rect around the pixmap (with gradient)
-    QPointF pixpos = frame.center() - (QPointF(w, h) / 2);
-    QRectF innerFrame(pixpos, QSizeF(w, h));
+    QPointF pixpos = frame.center() - (QPointF(pmSize.width(), pmSize.height()) / 2);
+    QRectF innerFrame(pixpos, pmSize);
     innerFrame.adjust(-4, -4, 4, 4);
     gradient.setStart(innerFrame.topLeft());
     gradient.setFinalStop(innerFrame.bottomRight());
@@ -106,14 +99,14 @@ void LayoutItem::paint(QPainter *painter,
     gradient.setStops(stops);
     painter->setBrush(QBrush(gradient));
     painter->drawRoundedRect(innerFrame, 10.0, 10.0);
-    painter->drawPixmap(pixpos, *m_pix);
+    painter->drawPixmap(pixpos, m_pix);
 }
 //! [2]
 
 //! [3]
 QRectF LayoutItem::boundingRect() const
 {
-    return QRectF(QPointF(0,0), geometry().size());
+    return QRectF(QPointF(0, 0), geometry().size());
 }
 //! [3]
 
@@ -133,7 +126,7 @@ QSizeF LayoutItem::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const
     case Qt::MinimumSize:
     case Qt::PreferredSize:
         // Do not allow a size smaller than the pixmap with two frames around it.
-        return m_pix->size() + QSize(12, 12);
+        return m_pix.size() + QSize(12, 12);
     case Qt::MaximumSize:
         return QSizeF(1000,1000);
     default:
diff --git a/examples/widgets/graphicsview/basicgraphicslayouts/layoutitem.h b/examples/widgets/graphicsview/basicgraphicslayouts/layoutitem.h
index 3535a26670..3dc431d513 100644
--- a/examples/widgets/graphicsview/basicgraphicslayouts/layoutitem.h
+++ b/examples/widgets/graphicsview/basicgraphicslayouts/layoutitem.h
@@ -53,23 +53,24 @@
 
 #include <QGraphicsLayoutItem>
 #include <QGraphicsItem>
+#include <QPixmap>
 
 //! [0]
 class LayoutItem : public QGraphicsLayoutItem, public QGraphicsItem
 {
 public:
-    LayoutItem(QGraphicsItem *parent = 0);
-    ~LayoutItem();
+    LayoutItem(QGraphicsItem *parent = nullptr);
+
     // Inherited from QGraphicsLayoutItem
     void setGeometry(const QRectF &geom) override;
     QSizeF sizeHint(Qt::SizeHint which, const QSizeF &constraint = QSizeF()) const override;
 
     // Inherited from QGraphicsItem
     QRectF boundingRect() const override;
-    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0) override;
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;
 
 private:
-    QPixmap *m_pix;
+    QPixmap m_pix;
 };
 //! [0]
 
diff --git a/examples/widgets/graphicsview/basicgraphicslayouts/window.h b/examples/widgets/graphicsview/basicgraphicslayouts/window.h
index dfe04ed196..c46082e552 100644
--- a/examples/widgets/graphicsview/basicgraphicslayouts/window.h
+++ b/examples/widgets/graphicsview/basicgraphicslayouts/window.h
@@ -54,11 +54,11 @@
 #include <QGraphicsWidget>
 
 //! [0]
-class Window : public QGraphicsWidget {
+class Window : public QGraphicsWidget
+{
     Q_OBJECT
-
 public:
-    Window(QGraphicsWidget *parent = 0);
+    Window(QGraphicsWidget *parent = nullptr);
 
 };
 //! [0]
diff --git a/examples/widgets/graphicsview/boxes/glbuffers.cpp b/examples/widgets/graphicsview/boxes/glbuffers.cpp
index b52b26c4ef..91de336af3 100644
--- a/examples/widgets/graphicsview/boxes/glbuffers.cpp
+++ b/examples/widgets/graphicsview/boxes/glbuffers.cpp
@@ -49,8 +49,6 @@
 ****************************************************************************/
 
 #include "glbuffers.h"
-#include <QtGui/qmatrix4x4.h>
-#include <QtCore/qmath.h>
 
 void qgluPerspective(GLdouble fovy, GLdouble aspect, GLdouble zNear, GLdouble zFar)
 {
@@ -65,7 +63,7 @@ void qgluPerspective(GLdouble fovy, GLdouble aspect, GLdouble zNear, GLdouble zF
 //                                  GLTexture                                 //
 //============================================================================//
 
-GLTexture::GLTexture() : m_texture(0), m_failed(false)
+GLTexture::GLTexture()
 {
     glGenTextures(1, &m_texture);
 }
@@ -83,7 +81,7 @@ GLTexture2D::GLTexture2D(int width, int height)
 {
     glBindTexture(GL_TEXTURE_2D, m_texture);
     glTexImage2D(GL_TEXTURE_2D, 0, 4, width, height, 0,
-        GL_BGRA, GL_UNSIGNED_BYTE, 0);
+        GL_BGRA, GL_UNSIGNED_BYTE, nullptr);
 
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
@@ -95,7 +93,7 @@ GLTexture2D::GLTexture2D(int width, int height)
 }
 
 
-GLTexture2D::GLTexture2D(const QString& fileName, int width, int height)
+GLTexture2D::GLTexture2D(const QString &fileName, int width, int height)
 {
     // TODO: Add error handling.
     QImage image(fileName);
@@ -162,7 +160,7 @@ GLTexture3D::GLTexture3D(int width, int height, int depth)
 
     glBindTexture(GL_TEXTURE_3D, m_texture);
     glTexImage3D(GL_TEXTURE_3D, 0, 4, width, height, depth, 0,
-        GL_BGRA, GL_UNSIGNED_BYTE, 0);
+        GL_BGRA, GL_UNSIGNED_BYTE, nullptr);
 
     glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_REPEAT);
     glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_REPEAT);
@@ -206,7 +204,7 @@ GLTextureCube::GLTextureCube(int size)
 
     for (int i = 0; i < 6; ++i)
         glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, 4, size, size, 0,
-            GL_BGRA, GL_UNSIGNED_BYTE, 0);
+            GL_BGRA, GL_UNSIGNED_BYTE, nullptr);
 
     glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
@@ -252,7 +250,7 @@ GLTextureCube::GLTextureCube(const QStringList &fileNames, int size)
     // Clear remaining faces.
     while (index < 6) {
         glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + index, 0, 4, size, size, 0,
-            GL_BGRA, GL_UNSIGNED_BYTE, 0);
+            GL_BGRA, GL_UNSIGNED_BYTE, nullptr);
         ++index;
     }
 
@@ -291,11 +289,8 @@ void GLTextureCube::unbind()
 //============================================================================//
 
 GLFrameBufferObject::GLFrameBufferObject(int width, int height)
-    : m_fbo(0)
-    , m_depthBuffer(0)
-    , m_width(width)
+    : m_width(width)
     , m_height(height)
-    , m_failed(false)
 {
     GLBUFFERS_ASSERT_OPENGL("GLFrameBufferObject::GLFrameBufferObject",
         glGenFramebuffersEXT && glGenRenderbuffersEXT && glBindRenderbufferEXT && glRenderbufferStorageEXT, return)
@@ -373,7 +368,7 @@ void GLRenderTargetCube::getViewMatrix(QMatrix4x4& mat, int face)
         return;
     }
 
-    static int perm[6][3] = {
+    static constexpr int perm[6][3] = {
         {2, 1, 0},
         {2, 1, 0},
         {0, 2, 1},
@@ -382,7 +377,7 @@ void GLRenderTargetCube::getViewMatrix(QMatrix4x4& mat, int face)
         {0, 1, 2},
     };
 
-    static float signs[6][3] = {
+    static constexpr float signs[6][3] = {
         {-1.0f, -1.0f, -1.0f},
         {+1.0f, -1.0f, +1.0f},
         {+1.0f, +1.0f, -1.0f},
diff --git a/examples/widgets/graphicsview/boxes/glbuffers.h b/examples/widgets/graphicsview/boxes/glbuffers.h
index e2363d561e..4318e8ac24 100644
--- a/examples/widgets/graphicsview/boxes/glbuffers.h
+++ b/examples/widgets/graphicsview/boxes/glbuffers.h
@@ -58,7 +58,7 @@
 #include <QtOpenGL>
 
 #define BUFFER_OFFSET(i) ((char*)0 + (i))
-#define SIZE_OF_MEMBER(cls, member) sizeof(static_cast<cls *>(0)->member)
+#define SIZE_OF_MEMBER(cls, member) sizeof(static_cast<cls *>(nullptr)->member)
 
 #define GLBUFFERS_ASSERT_OPENGL(prefix, assertion, returnStatement)                         \
 if (m_failed || !(assertion)) {                                                             \
@@ -82,8 +82,8 @@ public:
     virtual void unbind() = 0;
     virtual bool failed() const {return m_failed;}
 protected:
-    GLuint m_texture;
-    bool m_failed;
+    GLuint m_texture = 0;
+    bool m_failed = false;
 };
 
 class GLFrameBufferObject
@@ -98,17 +98,17 @@ public:
     virtual bool failed() const {return m_failed;}
 protected:
     void setAsRenderTarget(bool state = true);
-    GLuint m_fbo;
-    GLuint m_depthBuffer;
+    GLuint m_fbo = 0;
+    GLuint m_depthBuffer = 0;
     int m_width, m_height;
-    bool m_failed;
+    bool m_failed = false;
 };
 
 class GLTexture2D : public GLTexture
 {
 public:
     GLTexture2D(int width, int height);
-    explicit GLTexture2D(const QString& fileName, int width = 0, int height = 0);
+    explicit GLTexture2D(const QString &fileName, int width = 0, int height = 0);
     void load(int width, int height, QRgb *data);
     void bind() override;
     void unbind() override;
@@ -197,11 +197,7 @@ template<class T>
 class GLVertexBuffer
 {
 public:
-    GLVertexBuffer(int length, const T *data = 0, int mode = GL_STATIC_DRAW)
-        : m_length(0)
-        , m_mode(mode)
-        , m_buffer(0)
-        , m_failed(false)
+    GLVertexBuffer(int length, const T *data = nullptr, int mode = GL_STATIC_DRAW)
     {
         GLBUFFERS_ASSERT_OPENGL("GLVertexBuffer::GLVertexBuffer", glGenBuffers && glBindBuffer && glBufferData, return)
 
@@ -275,12 +271,12 @@ public:
 
     T *lock()
     {
-        GLBUFFERS_ASSERT_OPENGL("GLVertexBuffer::lock", glBindBuffer && glMapBuffer, return 0)
+        GLBUFFERS_ASSERT_OPENGL("GLVertexBuffer::lock", glBindBuffer && glMapBuffer, return nullptr)
 
         glBindBuffer(GL_ARRAY_BUFFER, m_buffer);
         //glBufferData(GL_ARRAY_BUFFER, m_length, NULL, m_mode);
         GLvoid* buffer = glMapBuffer(GL_ARRAY_BUFFER, GL_READ_WRITE);
-        m_failed = (buffer == 0);
+        m_failed = (buffer == nullptr);
         return reinterpret_cast<T *>(buffer);
     }
 
@@ -298,16 +294,17 @@ public:
     }
 
 private:
-    int m_length, m_mode;
-    GLuint m_buffer;
-    bool m_failed;
+    int m_length = 0;
+    int m_mode = 0;
+    GLuint m_buffer = 0;
+    bool m_failed = false;
 };
 
 template<class T>
 class GLIndexBuffer
 {
 public:
-    GLIndexBuffer(int length, const T *data = 0, int mode = GL_STATIC_DRAW)
+    GLIndexBuffer(int length, const T *data = nullptr, int mode = GL_STATIC_DRAW)
         : m_length(0)
         , m_mode(mode)
         , m_buffer(0)
@@ -345,11 +342,11 @@ public:
 
     T *lock()
     {
-        GLBUFFERS_ASSERT_OPENGL("GLIndexBuffer::lock", glBindBuffer && glMapBuffer, return 0)
+        GLBUFFERS_ASSERT_OPENGL("GLIndexBuffer::lock", glBindBuffer && glMapBuffer, return nullptr)
 
         glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_buffer);
         GLvoid* buffer = glMapBuffer(GL_ELEMENT_ARRAY_BUFFER, GL_READ_WRITE);
-        m_failed = (buffer == 0);
+        m_failed = (buffer == nullptr);
         return reinterpret_cast<T *>(buffer);
     }
 
diff --git a/examples/widgets/graphicsview/boxes/gltrianglemesh.h b/examples/widgets/graphicsview/boxes/gltrianglemesh.h
index 716c4de62e..e5c4f51514 100644
--- a/examples/widgets/graphicsview/boxes/gltrianglemesh.h
+++ b/examples/widgets/graphicsview/boxes/gltrianglemesh.h
@@ -51,13 +51,12 @@
 #ifndef GLTRIANGLEMESH_H
 #define GLTRIANGLEMESH_H
 
-//#include <GL/glew.h>
+#include "glbuffers.h"
 #include "glextensions.h"
 
 #include <QtWidgets>
 #include <QtOpenGL>
 
-#include "glbuffers.h"
 
 template<class TVertex, class TIndex>
 class GLTriangleMesh
diff --git a/examples/widgets/graphicsview/boxes/main.cpp b/examples/widgets/graphicsview/boxes/main.cpp
index b7242d529b..2b3e6d3389 100644
--- a/examples/widgets/graphicsview/boxes/main.cpp
+++ b/examples/widgets/graphicsview/boxes/main.cpp
@@ -48,13 +48,11 @@
 **
 ****************************************************************************/
 
-//#include <GL/glew.h>
 #include "glextensions.h"
-
 #include "scene.h"
 
-#include <QtWidgets>
 #include <QGLWidget>
+#include <QtWidgets>
 
 class GraphicsView : public QGraphicsView
 {
@@ -114,7 +112,7 @@ int main(int argc, char **argv)
     QApplication app(argc, argv);
 
     if ((QGLFormat::openGLVersionFlags() & QGLFormat::OpenGL_Version_1_5) == 0) {
-        QMessageBox::critical(0, "OpenGL features missing",
+        QMessageBox::critical(nullptr, "OpenGL features missing",
             "OpenGL version 1.5 or higher is required to run this demo.\n"
             "The program will now exit.");
         return -1;
@@ -125,7 +123,7 @@ int main(int argc, char **argv)
     widget->makeCurrent();
 
     if (!necessaryExtensionsSupported()) {
-        QMessageBox::critical(0, "OpenGL features missing",
+        QMessageBox::critical(nullptr, "OpenGL features missing",
             "The OpenGL extensions required to run this demo are missing.\n"
             "The program will now exit.");
         delete widget;
@@ -134,7 +132,7 @@ int main(int argc, char **argv)
 
     // Check if all the necessary functions are resolved.
     if (!getGLExtensionFunctions().resolve(widget->context())) {
-        QMessageBox::critical(0, "OpenGL features missing",
+        QMessageBox::critical(nullptr, "OpenGL features missing",
             "Failed to resolve OpenGL functions required to run this demo.\n"
             "The program will now exit.");
         delete widget;
@@ -142,7 +140,7 @@ int main(int argc, char **argv)
     }
 
     // TODO: Make conditional for final release
-    QMessageBox::information(0, "For your information",
+    QMessageBox::information(nullptr, "For your information",
         "This demo can be GPU and CPU intensive and may\n"
         "work poorly or not at all on your system.");
 
diff --git a/examples/widgets/graphicsview/boxes/qtbox.cpp b/examples/widgets/graphicsview/boxes/qtbox.cpp
index 68d5c251f4..8713aac05d 100644
--- a/examples/widgets/graphicsview/boxes/qtbox.cpp
+++ b/examples/widgets/graphicsview/boxes/qtbox.cpp
@@ -50,28 +50,23 @@
 
 #include "qtbox.h"
 
-const qreal ROTATE_SPEED_X = 30.0 / 1000.0;
-const qreal ROTATE_SPEED_Y = 20.0 / 1000.0;
-const qreal ROTATE_SPEED_Z = 40.0 / 1000.0;
-const int MAX_ITEM_SIZE = 512;
-const int MIN_ITEM_SIZE = 16;
+constexpr qreal ROTATE_SPEED_X = 30.0 / 1000.0;
+constexpr qreal ROTATE_SPEED_Y = 20.0 / 1000.0;
+constexpr qreal ROTATE_SPEED_Z = 40.0 / 1000.0;
+constexpr int MAX_ITEM_SIZE = 512;
+constexpr int MIN_ITEM_SIZE = 16;
 
 //============================================================================//
 //                                  ItemBase                                  //
 //============================================================================//
 
-ItemBase::ItemBase(int size, int x, int y) : m_size(size), m_isResizing(false)
+ItemBase::ItemBase(int size, int x, int y) : m_size(size), m_startTime(QTime::currentTime())
 {
     setFlag(QGraphicsItem::ItemIsMovable, true);
     setFlag(QGraphicsItem::ItemIsSelectable, true);
     setFlag(QGraphicsItem::ItemIsFocusable, true);
     setAcceptHoverEvents(true);
     setPos(x, y);
-    m_startTime = QTime::currentTime();
-}
-
-ItemBase::~ItemBase()
-{
 }
 
 QRectF ItemBase::boundingRect() const
@@ -252,10 +247,7 @@ void ItemBase::wheelEvent(QGraphicsSceneWheelEvent *event)
 {
     prepareGeometryChange();
     m_size = int(m_size * qExp(-event->delta() / 600.0));
-    if (m_size > MAX_ITEM_SIZE)
-        m_size = MAX_ITEM_SIZE;
-    else if (m_size < MIN_ITEM_SIZE)
-        m_size = MIN_ITEM_SIZE;
+    m_size = qBound(MIN_ITEM_SIZE, m_size, MAX_ITEM_SIZE);
 }
 
 int ItemBase::type() const
@@ -273,7 +265,7 @@ bool ItemBase::isInResizeArea(const QPointF &pos)
 //                                    QtBox                                   //
 //============================================================================//
 
-QtBox::QtBox(int size, int x, int y) : ItemBase(size, x, y), m_texture(0)
+QtBox::QtBox(int size, int x, int y) : ItemBase(size, x, y)
 {
     for (int i = 0; i < 8; ++i) {
         m_vertices[i].setX(i & 1 ? 0.5f : -0.5f);
@@ -294,8 +286,7 @@ QtBox::QtBox(int size, int x, int y) : ItemBase(size, x, y), m_texture(0)
 
 QtBox::~QtBox()
 {
-    if (m_texture)
-        delete m_texture;
+    delete m_texture;
 }
 
 ItemBase *QtBox::createNew(int size, int x, int y)
@@ -337,7 +328,7 @@ void QtBox::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWi
     glEnable(GL_COLOR_MATERIAL);
     glEnable(GL_NORMALIZE);
 
-    if(m_texture == 0)
+    if (m_texture == nullptr)
         m_texture = new GLTexture2D(":/res/boxes/qt-logo.jpg", 64, 64);
     m_texture->bind();
     glEnable(GL_TEXTURE_2D);
@@ -405,9 +396,8 @@ void QtBox::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWi
 //============================================================================//
 
 CircleItem::CircleItem(int size, int x, int y) : ItemBase(size, x, y)
-{
-     m_color = QColor::fromHsv(QRandomGenerator::global()->bounded(360), 255, 255);
-}
+    , m_color(QColor::fromHsv(QRandomGenerator::global()->bounded(360), 255, 255))
+{}
 
 void CircleItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
 {
@@ -455,9 +445,8 @@ ItemBase *CircleItem::createNew(int size, int x, int y)
 //============================================================================//
 
 SquareItem::SquareItem(int size, int x, int y) : ItemBase(size, x, y)
-{
-    m_image = QPixmap(":/res/boxes/square.jpg");
-}
+    , m_image(QPixmap(":/res/boxes/square.jpg"))
+{}
 
 void SquareItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
 {
diff --git a/examples/widgets/graphicsview/boxes/qtbox.h b/examples/widgets/graphicsview/boxes/qtbox.h
index f8ee9bdb0a..84c8cb1d93 100644
--- a/examples/widgets/graphicsview/boxes/qtbox.h
+++ b/examples/widgets/graphicsview/boxes/qtbox.h
@@ -51,18 +51,17 @@
 #ifndef QTBOX_H
 #define QTBOX_H
 
-#include <QtWidgets>
-
-#include <QtGui/qvector3d.h>
 #include "glbuffers.h"
 
+#include <QtWidgets>
+#include <QVector3D>
+
 class ItemBase : public QGraphicsItem
 {
 public:
     enum { Type = UserType + 1 };
 
     ItemBase(int size, int x, int y);
-    virtual ~ItemBase();
     QRectF boundingRect() const override;
     void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override;
 protected:
@@ -84,7 +83,7 @@ protected:
 
     int m_size;
     QTime m_startTime;
-    bool m_isResizing;
+    bool m_isResizing = false;
 };
 
 class QtBox : public ItemBase
@@ -99,7 +98,7 @@ private:
     QVector3D m_vertices[8];
     QVector3D m_texCoords[4];
     QVector3D m_normals[6];
-    GLTexture *m_texture;
+    GLTexture *m_texture = nullptr;
 };
 
 class CircleItem : public ItemBase
diff --git a/examples/widgets/graphicsview/boxes/roundedbox.h b/examples/widgets/graphicsview/boxes/roundedbox.h
index ebc2dbd36e..a1f15cd631 100644
--- a/examples/widgets/graphicsview/boxes/roundedbox.h
+++ b/examples/widgets/graphicsview/boxes/roundedbox.h
@@ -51,16 +51,12 @@
 #ifndef ROUNDEDBOX_H
 #define ROUNDEDBOX_H
 
-//#include <GL/glew.h>
+#include "glbuffers.h"
 #include "glextensions.h"
-
-#include <QtWidgets>
-#include <QtOpenGL>
-
 #include "gltrianglemesh.h"
-#include <QtGui/qvector3d.h>
-#include <QtGui/qvector2d.h>
-#include "glbuffers.h"
+
+#include <QVector2D>
+#include <QVector3D>
 
 struct P3T2N3Vertex
 {
diff --git a/examples/widgets/graphicsview/boxes/scene.cpp b/examples/widgets/graphicsview/boxes/scene.cpp
index a9995efa27..b344f65561 100644
--- a/examples/widgets/graphicsview/boxes/scene.cpp
+++ b/examples/widgets/graphicsview/boxes/scene.cpp
@@ -48,45 +48,15 @@
 **
 ****************************************************************************/
 
-#include <QDebug>
 #include "scene.h"
-#include <QtCore/QRandomGenerator>
-#include <QtGui/qmatrix4x4.h>
-#include <QtGui/qvector3d.h>
+
+#include <QMatrix4x4>
+#include <QRandomGenerator>
+#include <QVector3D>
 #include <qmath.h>
 
 #include "3rdparty/fbm.h"
 
-void checkGLErrors(const QString& prefix)
-{
-    switch (glGetError()) {
-    case GL_NO_ERROR:
-        //qDebug() << prefix << tr("No error.");
-        break;
-    case GL_INVALID_ENUM:
-        qDebug() << prefix << QObject::tr("Invalid enum.");
-        break;
-    case GL_INVALID_VALUE:
-        qDebug() << prefix << QObject::tr("Invalid value.");
-        break;
-    case GL_INVALID_OPERATION:
-        qDebug() << prefix << QObject::tr("Invalid operation.");
-        break;
-    case GL_STACK_OVERFLOW:
-        qDebug() << prefix << QObject::tr("Stack overflow.");
-        break;
-    case GL_STACK_UNDERFLOW:
-        qDebug() << prefix << QObject::tr("Stack underflow.");
-        break;
-    case GL_OUT_OF_MEMORY:
-        qDebug() << prefix << QObject::tr("Out of memory.");
-        break;
-    default:
-        qDebug() << prefix << QObject::tr("Unknown error.");
-        break;
-    }
-}
-
 //============================================================================//
 //                                  ColorEdit                                 //
 //============================================================================//
@@ -126,7 +96,7 @@ void ColorEdit::mousePressEvent(QMouseEvent *event)
 {
     if (event->button() == Qt::LeftButton) {
         QColor color(m_color);
-        QColorDialog dialog(color, 0);
+        QColorDialog dialog(color, nullptr);
         dialog.setOption(QColorDialog::ShowAlphaChannel, true);
         dialog.move(280, 120);
         if (dialog.exec() == QDialog::Rejected)
@@ -179,17 +149,6 @@ void FloatEdit::editDone()
 //============================================================================//
 //                           TwoSidedGraphicsWidget                           //
 //============================================================================//
-
-TwoSidedGraphicsWidget::TwoSidedGraphicsWidget(QGraphicsScene *scene)
-    : QObject(scene)
-    , m_current(0)
-    , m_angle(0)
-    , m_delta(0)
-{
-    for (int i = 0; i < 2; ++i)
-        m_proxyWidgets[i] = 0;
-}
-
 void TwoSidedGraphicsWidget::setWidget(int index, QWidget *widget)
 {
     if (index < 0 || index >= 2)
@@ -201,8 +160,7 @@ void TwoSidedGraphicsWidget::setWidget(int index, QWidget *widget)
     GraphicsWidget *proxy = new GraphicsWidget;
     proxy->setWidget(widget);
 
-    if (m_proxyWidgets[index])
-        delete m_proxyWidgets[index];
+    delete m_proxyWidgets[index];
     m_proxyWidgets[index] = proxy;
 
     proxy->setCacheMode(QGraphicsItem::ItemCoordinateCache);
@@ -219,7 +177,7 @@ QWidget *TwoSidedGraphicsWidget::widget(int index)
     if (index < 0 || index >= 2)
     {
         qWarning("TwoSidedGraphicsWidget::widget: Index out of bounds, index == %d", index);
-        return 0;
+        return nullptr;
     }
     return m_proxyWidgets[index]->widget();
 }
@@ -289,7 +247,7 @@ void GraphicsWidget::paint(QPainter *painter, const QStyleOptionGraphicsItem *op
 //============================================================================//
 
 RenderOptionsDialog::RenderOptionsDialog()
-    : QDialog(0, Qt::CustomizeWindowHint | Qt::WindowTitleHint)
+    : QDialog(nullptr, Qt::CustomizeWindowHint | Qt::WindowTitleHint)
 {
     setWindowOpacity(0.75);
     setWindowTitle(tr("Options (double click to flip)"));
@@ -423,7 +381,7 @@ void RenderOptionsDialog::mouseDoubleClickEvent(QMouseEvent *event)
 //============================================================================//
 
 ItemDialog::ItemDialog()
-    : QDialog(0, Qt::CustomizeWindowHint | Qt::WindowTitleHint)
+    : QDialog(nullptr, Qt::CustomizeWindowHint | Qt::WindowTitleHint)
 {
     setWindowTitle(tr("Items (double click to flip)"));
     setWindowOpacity(0.75);
@@ -487,10 +445,10 @@ Scene::Scene(int width, int height, int maxTextureSize)
     , m_currentTexture(0)
     , m_dynamicCubemap(false)
     , m_updateAllCubemaps(true)
-    , m_box(0)
-    , m_vertexShader(0)
-    , m_environmentShader(0)
-    , m_environmentProgram(0)
+    , m_box(nullptr)
+    , m_vertexShader(nullptr)
+    , m_environmentShader(nullptr)
+    , m_environmentProgram(nullptr)
 {
     setSceneRect(0, 0, width, height);
 
@@ -564,9 +522,8 @@ void Scene::initGL()
 
     const int NOISE_SIZE = 128; // for a different size, B and BM in fbm.c must also be changed
     m_noise = new GLTexture3D(NOISE_SIZE, NOISE_SIZE, NOISE_SIZE);
-    QRgb *data = new QRgb[NOISE_SIZE * NOISE_SIZE * NOISE_SIZE];
-    memset(data, 0, NOISE_SIZE * NOISE_SIZE * NOISE_SIZE * sizeof(QRgb));
-    QRgb *p = data;
+    QVector<QRgb> data(NOISE_SIZE * NOISE_SIZE * NOISE_SIZE, QRgb(0));
+    QRgb *p = data.data();
     float pos[3];
     for (int k = 0; k < NOISE_SIZE; ++k) {
         pos[2] = k * (0x20 / (float)NOISE_SIZE);
@@ -581,8 +538,7 @@ void Scene::initGL()
             }
         }
     }
-    m_noise->load(NOISE_SIZE, NOISE_SIZE, NOISE_SIZE, data);
-    delete[] data;
+    m_noise->load(NOISE_SIZE, NOISE_SIZE, NOISE_SIZE, data.data());
 
     m_mainCubemap = new GLRenderTargetCube(512);
 
@@ -634,7 +590,7 @@ void Scene::initGL()
         m_renderOptions->addShader(file.baseName());
 
         program->bind();
-        m_cubemaps << ((program->uniformLocation("env") != -1) ? new GLRenderTargetCube(qMin(256, m_maxTextureSize)) : 0);
+        m_cubemaps << ((program->uniformLocation("env") != -1) ? new GLRenderTargetCube(qMin(256, m_maxTextureSize)) : nullptr);
         program->release();
     }
 
diff --git a/examples/widgets/graphicsview/boxes/scene.h b/examples/widgets/graphicsview/boxes/scene.h
index ffff01358f..5d65dc71e2 100644
--- a/examples/widgets/graphicsview/boxes/scene.h
+++ b/examples/widgets/graphicsview/boxes/scene.h
@@ -51,17 +51,12 @@
 #ifndef SCENE_H
 #define SCENE_H
 
-//#include <GL/glew.h>
+#include "glbuffers.h"
 #include "glextensions.h"
-
-#include <QtWidgets>
-#include <QtOpenGL>
-
-#include "roundedbox.h"
 #include "gltrianglemesh.h"
-#include "trackball.h"
-#include "glbuffers.h"
 #include "qtbox.h"
+#include "roundedbox.h"
+#include "trackball.h"
 
 QT_BEGIN_NAMESPACE
 class QMatrix4x4;
@@ -116,7 +111,7 @@ private:
 class GraphicsWidget : public QGraphicsProxyWidget
 {
 public:
-    GraphicsWidget() : QGraphicsProxyWidget(0, Qt::Window) {}
+    GraphicsWidget() : QGraphicsProxyWidget(nullptr, Qt::Window) {}
 protected:
     QVariant itemChange(GraphicsItemChange change, const QVariant &value) override;
     void resizeEvent(QGraphicsSceneResizeEvent *event) override;
@@ -127,7 +122,7 @@ class TwoSidedGraphicsWidget : public QObject
 {
     Q_OBJECT
 public:
-    TwoSidedGraphicsWidget(QGraphicsScene *scene);
+    using QObject::QObject;
     void setWidget(int index, QWidget *widget);
     QWidget *widget(int index);
 public slots:
@@ -135,10 +130,10 @@ public slots:
 protected slots:
     void animateFlip();
 private:
-    GraphicsWidget *m_proxyWidgets[2];
-    int m_current;
-    int m_angle; // angle in degrees
-    int m_delta;
+    GraphicsWidget *m_proxyWidgets[2] = {nullptr, nullptr};
+    int m_current = 0;
+    int m_angle = 0; // angle in degrees
+    int m_delta = 0;
 };
 
 class RenderOptionsDialog : public QDialog
diff --git a/examples/widgets/graphicsview/boxes/trackball.cpp b/examples/widgets/graphicsview/boxes/trackball.cpp
index 794ce7ac37..b9dfc1fc7f 100644
--- a/examples/widgets/graphicsview/boxes/trackball.cpp
+++ b/examples/widgets/graphicsview/boxes/trackball.cpp
@@ -50,34 +50,21 @@
 
 #include "trackball.h"
 #include "scene.h"
-#include <qmath.h>
-#include <cmath>
 
 //============================================================================//
 //                                  TrackBall                                 //
 //============================================================================//
 
 TrackBall::TrackBall(TrackMode mode)
-    : m_angularVelocity(0)
-    , m_paused(false)
-    , m_pressed(false)
-    , m_mode(mode)
+    : TrackBall(0, QVector3D(0, 1, 0), mode)
 {
-    m_axis = QVector3D(0, 1, 0);
-    m_rotation = QQuaternion();
-    m_lastTime = QTime::currentTime();
 }
 
 TrackBall::TrackBall(float angularVelocity, const QVector3D& axis, TrackMode mode)
     : m_axis(axis)
     , m_angularVelocity(angularVelocity)
-    , m_paused(false)
-    , m_pressed(false)
     , m_mode(mode)
-{
-    m_rotation = QQuaternion();
-    m_lastTime = QTime::currentTime();
-}
+{}
 
 void TrackBall::push(const QPointF& p, const QQuaternion &)
 {
diff --git a/examples/widgets/graphicsview/boxes/trackball.h b/examples/widgets/graphicsview/boxes/trackball.h
index e65080e089..af90e4d842 100644
--- a/examples/widgets/graphicsview/boxes/trackball.h
+++ b/examples/widgets/graphicsview/boxes/trackball.h
@@ -51,10 +51,9 @@
 #ifndef TRACKBALL_H
 #define TRACKBALL_H
 
-#include <QtWidgets>
-
-#include <QtGui/qvector3d.h>
-#include <QtGui/qquaternion.h>
+#include <QQuaternion>
+#include <QTime>
+#include <QVector3D>
 
 class TrackBall
 {
@@ -65,24 +64,24 @@ public:
         Sphere,
     };
     TrackBall(TrackMode mode = Sphere);
-    TrackBall(float angularVelocity, const QVector3D& axis, TrackMode mode = Sphere);
+    TrackBall(float angularVelocity, const QVector3D &axis, TrackMode mode = Sphere);
     // coordinates in [-1,1]x[-1,1]
-    void push(const QPointF& p, const QQuaternion &transformation);
-    void move(const QPointF& p, const QQuaternion &transformation);
-    void release(const QPointF& p, const QQuaternion &transformation);
+    void push(const QPointF &p, const QQuaternion &transformation);
+    void move(const QPointF &p, const QQuaternion &transformation);
+    void release(const QPointF &p, const QQuaternion &transformation);
     void start(); // starts clock
     void stop(); // stops clock
     QQuaternion rotation() const;
 private:
     QQuaternion m_rotation;
-    QVector3D m_axis;
-    float m_angularVelocity;
+    QVector3D m_axis = QVector3D(0, 1, 0);
+    float m_angularVelocity = 0;
 
     QPointF m_lastPos;
-    QTime m_lastTime;
-    bool m_paused;
-    bool m_pressed;
+    QTime m_lastTime = QTime::currentTime();
     TrackMode m_mode;
+    bool m_paused = false;
+    bool m_pressed = false;
 };
 
 #endif
diff --git a/examples/widgets/graphicsview/chip/chip.cpp b/examples/widgets/graphicsview/chip/chip.cpp
index 3d2bbdfcef..25f4ccc2e9 100644
--- a/examples/widgets/graphicsview/chip/chip.cpp
+++ b/examples/widgets/graphicsview/chip/chip.cpp
@@ -50,7 +50,9 @@
 
 #include "chip.h"
 
-#include <QtWidgets>
+#include <QGraphicsSceneMouseEvent>
+#include <QPainter>
+#include <QStyleOptionGraphicsItem>
 
 Chip::Chip(const QColor &color, int x, int y)
 {
diff --git a/examples/widgets/graphicsview/chip/mainwindow.cpp b/examples/widgets/graphicsview/chip/mainwindow.cpp
index b6e1313eb2..f2f89c8722 100644
--- a/examples/widgets/graphicsview/chip/mainwindow.cpp
+++ b/examples/widgets/graphicsview/chip/mainwindow.cpp
@@ -56,13 +56,11 @@
 #include <QSplitter>
 
 MainWindow::MainWindow(QWidget *parent)
-    : QWidget(parent)
+    : QWidget(parent), scene(new QGraphicsScene(this))
+    , h1Splitter(new QSplitter(this)), h2Splitter(new QSplitter(this))
 {
     populateScene();
 
-    h1Splitter = new QSplitter;
-    h2Splitter = new QSplitter;
-
     QSplitter *vSplitter = new QSplitter;
     vSplitter->setOrientation(Qt::Vertical);
     vSplitter->addWidget(h1Splitter);
@@ -93,8 +91,6 @@ MainWindow::MainWindow(QWidget *parent)
 
 void MainWindow::populateScene()
 {
-    scene = new QGraphicsScene(this);
-
     QImage image(":/qt4logo.png");
 
     // Populate scene
diff --git a/examples/widgets/graphicsview/chip/mainwindow.h b/examples/widgets/graphicsview/chip/mainwindow.h
index 9417d12d7a..3f91b2efb4 100644
--- a/examples/widgets/graphicsview/chip/mainwindow.h
+++ b/examples/widgets/graphicsview/chip/mainwindow.h
@@ -62,7 +62,7 @@ class MainWindow : public QWidget
 {
     Q_OBJECT
 public:
-    MainWindow(QWidget *parent = 0);
+    MainWindow(QWidget *parent = nullptr);
 
 private:
     void setupMatrix();
diff --git a/examples/widgets/graphicsview/chip/view.cpp b/examples/widgets/graphicsview/chip/view.cpp
index 7d5fd699a4..21998dc2df 100644
--- a/examples/widgets/graphicsview/chip/view.cpp
+++ b/examples/widgets/graphicsview/chip/view.cpp
@@ -62,7 +62,7 @@
 #else
 #include <QtWidgets>
 #endif
-#include <qmath.h>
+#include <QtMath>
 
 #if QT_CONFIG(wheelevent)
 void GraphicsView::wheelEvent(QWheelEvent *e)
diff --git a/examples/widgets/graphicsview/chip/view.h b/examples/widgets/graphicsview/chip/view.h
index 89b2e813f1..ea7bd414f5 100644
--- a/examples/widgets/graphicsview/chip/view.h
+++ b/examples/widgets/graphicsview/chip/view.h
@@ -81,7 +81,7 @@ class View : public QFrame
 {
     Q_OBJECT
 public:
-    explicit View(const QString &name, QWidget *parent = 0);
+    explicit View(const QString &name, QWidget *parent = nullptr);
 
     QGraphicsView *view() const;
 
diff --git a/examples/widgets/graphicsview/collidingmice/main.cpp b/examples/widgets/graphicsview/collidingmice/main.cpp
index dfb20815b9..ef6d6cca64 100644
--- a/examples/widgets/graphicsview/collidingmice/main.cpp
+++ b/examples/widgets/graphicsview/collidingmice/main.cpp
@@ -48,13 +48,12 @@
 **
 ****************************************************************************/
 
+#include <QtMath>
 #include <QtWidgets>
 
-#include <math.h>
-
 #include "mouse.h"
 
-static const int MouseCount = 7;
+static constexpr int MouseCount = 7;
 
 //! [0]
 int main(int argc, char **argv)
diff --git a/examples/widgets/graphicsview/collidingmice/mouse.cpp b/examples/widgets/graphicsview/collidingmice/mouse.cpp
index a8fcc05d76..556e58d19b 100644
--- a/examples/widgets/graphicsview/collidingmice/mouse.cpp
+++ b/examples/widgets/graphicsview/collidingmice/mouse.cpp
@@ -54,10 +54,10 @@
 #include <QPainter>
 #include <QRandomGenerator>
 #include <QStyleOption>
-#include <qmath.h>
+#include <QtMath>
 
-const qreal Pi = M_PI;
-const qreal TwoPi = 2 * M_PI;
+constexpr qreal Pi = M_PI;
+constexpr qreal TwoPi = 2 * M_PI;
 
 static qreal normalizeAngle(qreal angle)
 {
@@ -70,8 +70,7 @@ static qreal normalizeAngle(qreal angle)
 
 //! [0]
 Mouse::Mouse()
-    : angle(0), speed(0), mouseEyeDirection(0),
-      color(QRandomGenerator::global()->bounded(256), QRandomGenerator::global()->bounded(256), QRandomGenerator::global()->bounded(256))
+    : color(QRandomGenerator::global()->bounded(256), QRandomGenerator::global()->bounded(256), QRandomGenerator::global()->bounded(256))
 {
     setRotation(QRandomGenerator::global()->bounded(360 * 16));
 }
diff --git a/examples/widgets/graphicsview/collidingmice/mouse.h b/examples/widgets/graphicsview/collidingmice/mouse.h
index bd9e592242..4b165fced6 100644
--- a/examples/widgets/graphicsview/collidingmice/mouse.h
+++ b/examples/widgets/graphicsview/collidingmice/mouse.h
@@ -68,9 +68,9 @@ protected:
     void advance(int step) override;
 
 private:
-    qreal angle;
-    qreal speed;
-    qreal mouseEyeDirection;
+    qreal angle = 0;
+    qreal speed = 0;
+    qreal mouseEyeDirection = 0;
     QColor color;
 };
 //! [0]
diff --git a/examples/widgets/graphicsview/diagramscene/arrow.cpp b/examples/widgets/graphicsview/diagramscene/arrow.cpp
index 525e0b3fbb..9b2472bb33 100644
--- a/examples/widgets/graphicsview/diagramscene/arrow.cpp
+++ b/examples/widgets/graphicsview/diagramscene/arrow.cpp
@@ -50,19 +50,17 @@
 
 
 #include "arrow.h"
+#include "diagramitem.h"
 
-#include <qmath.h>
-#include <QPen>
 #include <QPainter>
+#include <QPen>
+#include <QtMath>
 
 //! [0]
 Arrow::Arrow(DiagramItem *startItem, DiagramItem *endItem, QGraphicsItem *parent)
-    : QGraphicsLineItem(parent)
+    : QGraphicsLineItem(parent), myStartItem(startItem), myEndItem(endItem)
 {
-    myStartItem = startItem;
-    myEndItem = endItem;
     setFlag(QGraphicsItem::ItemIsSelectable, true);
-    myColor = Qt::black;
     setPen(QPen(myColor, 2, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin));
 }
 //! [0]
@@ -98,7 +96,7 @@ void Arrow::updatePosition()
 
 //! [4]
 void Arrow::paint(QPainter *painter, const QStyleOptionGraphicsItem *,
-          QWidget *)
+                  QWidget *)
 {
     if (myStartItem->collidesWithItem(myEndItem))
         return;
diff --git a/examples/widgets/graphicsview/diagramscene/arrow.h b/examples/widgets/graphicsview/diagramscene/arrow.h
index e0fa389d53..13001959bd 100644
--- a/examples/widgets/graphicsview/diagramscene/arrow.h
+++ b/examples/widgets/graphicsview/diagramscene/arrow.h
@@ -53,16 +53,7 @@
 
 #include <QGraphicsLineItem>
 
-#include "diagramitem.h"
-
-QT_BEGIN_NAMESPACE
-class QGraphicsPolygonItem;
-class QGraphicsLineItem;
-class QGraphicsScene;
-class QRectF;
-class QGraphicsSceneMouseEvent;
-class QPainterPath;
-QT_END_NAMESPACE
+class DiagramItem;
 
 //! [0]
 class Arrow : public QGraphicsLineItem
@@ -71,7 +62,7 @@ public:
     enum { Type = UserType + 4 };
 
     Arrow(DiagramItem *startItem, DiagramItem *endItem,
-      QGraphicsItem *parent = 0);
+          QGraphicsItem *parent = nullptr);
 
     int type() const override { return Type; }
     QRectF boundingRect() const override;
@@ -83,13 +74,14 @@ public:
     void updatePosition();
 
 protected:
-    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0) override;
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
+               QWidget *widget = nullptr) override;
 
 private:
     DiagramItem *myStartItem;
     DiagramItem *myEndItem;
-    QColor myColor;
     QPolygonF arrowHead;
+    QColor myColor = Qt::black;
 };
 //! [0]
 
diff --git a/examples/widgets/graphicsview/diagramscene/diagramitem.cpp b/examples/widgets/graphicsview/diagramscene/diagramitem.cpp
index 3aa685635e..8ec577170b 100644
--- a/examples/widgets/graphicsview/diagramscene/diagramitem.cpp
+++ b/examples/widgets/graphicsview/diagramscene/diagramitem.cpp
@@ -58,12 +58,10 @@
 
 //! [0]
 DiagramItem::DiagramItem(DiagramType diagramType, QMenu *contextMenu,
-             QGraphicsItem *parent)
-    : QGraphicsPolygonItem(parent)
+                         QGraphicsItem *parent)
+    : QGraphicsPolygonItem(parent), myDiagramType(diagramType)
+    , myContextMenu(contextMenu)
 {
-    myDiagramType = diagramType;
-    myContextMenu = contextMenu;
-
     QPainterPath path;
     switch (myDiagramType) {
         case StartEnd:
@@ -101,17 +99,17 @@ DiagramItem::DiagramItem(DiagramType diagramType, QMenu *contextMenu,
 //! [1]
 void DiagramItem::removeArrow(Arrow *arrow)
 {
-    int index = arrows.indexOf(arrow);
-
-    if (index != -1)
-        arrows.removeAt(index);
+    arrows.removeAll(arrow);
 }
 //! [1]
 
 //! [2]
 void DiagramItem::removeArrows()
 {
-    for (Arrow *arrow : qAsConst(arrows)) {
+    // need a copy here since removeArrow() will
+    // modify the arrows container
+    const auto arrowsCopy = arrows;
+    for (Arrow *arrow : arrowsCopy) {
         arrow->startItem()->removeArrow(arrow);
         arrow->endItem()->removeArrow(arrow);
         scene()->removeItem(arrow);
diff --git a/examples/widgets/graphicsview/diagramscene/diagramitem.h b/examples/widgets/graphicsview/diagramscene/diagramitem.h
index 3a43ec57fc..ffaea4b7a8 100644
--- a/examples/widgets/graphicsview/diagramscene/diagramitem.h
+++ b/examples/widgets/graphicsview/diagramscene/diagramitem.h
@@ -52,19 +52,12 @@
 #define DIAGRAMITEM_H
 
 #include <QGraphicsPixmapItem>
-#include <QList>
+#include <QVector>
 
 QT_BEGIN_NAMESPACE
 class QPixmap;
-class QGraphicsItem;
-class QGraphicsScene;
-class QTextEdit;
-class QGraphicsSceneMouseEvent;
-class QMenu;
 class QGraphicsSceneContextMenuEvent;
-class QPainter;
-class QStyleOptionGraphicsItem;
-class QWidget;
+class QMenu;
 class QPolygonF;
 QT_END_NAMESPACE
 
@@ -77,7 +70,7 @@ public:
     enum { Type = UserType + 15 };
     enum DiagramType { Step, Conditional, StartEnd, Io };
 
-    DiagramItem(DiagramType diagramType, QMenu *contextMenu, QGraphicsItem *parent = 0);
+    DiagramItem(DiagramType diagramType, QMenu *contextMenu, QGraphicsItem *parent = nullptr);
 
     void removeArrow(Arrow *arrow);
     void removeArrows();
@@ -85,7 +78,7 @@ public:
     QPolygonF polygon() const { return myPolygon; }
     void addArrow(Arrow *arrow);
     QPixmap image() const;
-    int type() const override { return Type;}
+    int type() const override { return Type; }
 
 protected:
     void contextMenuEvent(QGraphicsSceneContextMenuEvent *event) override;
@@ -95,7 +88,7 @@ private:
     DiagramType myDiagramType;
     QPolygonF myPolygon;
     QMenu *myContextMenu;
-    QList<Arrow *> arrows;
+    QVector<Arrow *> arrows;
 };
 //! [0]
 
diff --git a/examples/widgets/graphicsview/diagramscene/diagramscene.cpp b/examples/widgets/graphicsview/diagramscene/diagramscene.cpp
index 40272834c3..d0688d8552 100644
--- a/examples/widgets/graphicsview/diagramscene/diagramscene.cpp
+++ b/examples/widgets/graphicsview/diagramscene/diagramscene.cpp
@@ -51,8 +51,8 @@
 #include "diagramscene.h"
 #include "arrow.h"
 
-#include <QTextCursor>
 #include <QGraphicsSceneMouseEvent>
+#include <QTextCursor>
 
 //! [0]
 DiagramScene::DiagramScene(QMenu *itemMenu, QObject *parent)
@@ -61,8 +61,8 @@ DiagramScene::DiagramScene(QMenu *itemMenu, QObject *parent)
     myItemMenu = itemMenu;
     myMode = MoveItem;
     myItemType = DiagramItem::Step;
-    line = 0;
-    textItem = 0;
+    line = nullptr;
+    textItem = nullptr;
     myItemColor = Qt::white;
     myTextColor = Qt::black;
     myLineColor = Qt::black;
@@ -188,7 +188,7 @@ void DiagramScene::mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent)
 //! [10]
 void DiagramScene::mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent)
 {
-    if (myMode == InsertLine && line != 0) {
+    if (myMode == InsertLine && line != nullptr) {
         QLineF newLine(line->line().p1(), mouseEvent->scenePos());
         line->setLine(newLine);
     } else if (myMode == MoveItem) {
@@ -200,7 +200,7 @@ void DiagramScene::mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent)
 //! [11]
 void DiagramScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent)
 {
-    if (line != 0 && myMode == InsertLine) {
+    if (line != nullptr && myMode == InsertLine) {
         QList<QGraphicsItem *> startItems = items(line->line().p1());
         if (startItems.count() && startItems.first() == line)
             startItems.removeFirst();
@@ -228,7 +228,7 @@ void DiagramScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent)
         }
     }
 //! [12] //! [13]
-    line = 0;
+    line = nullptr;
     QGraphicsScene::mouseReleaseEvent(mouseEvent);
 }
 //! [13]
diff --git a/examples/widgets/graphicsview/diagramscene/diagramscene.h b/examples/widgets/graphicsview/diagramscene/diagramscene.h
index 15063d58b7..5682468ef6 100644
--- a/examples/widgets/graphicsview/diagramscene/diagramscene.h
+++ b/examples/widgets/graphicsview/diagramscene/diagramscene.h
@@ -74,7 +74,7 @@ class DiagramScene : public QGraphicsScene
 public:
     enum Mode { InsertItem, InsertLine, InsertText, MoveItem };
 
-    explicit DiagramScene(QMenu *itemMenu, QObject *parent = 0);
+    explicit DiagramScene(QMenu *itemMenu, QObject *parent = nullptr);
     QFont font() const { return myFont; }
     QColor textColor() const { return myTextColor; }
     QColor itemColor() const { return myItemColor; }
diff --git a/examples/widgets/graphicsview/diagramscene/diagramtextitem.h b/examples/widgets/graphicsview/diagramscene/diagramtextitem.h
index f5d3d3b95e..7809609e24 100644
--- a/examples/widgets/graphicsview/diagramscene/diagramtextitem.h
+++ b/examples/widgets/graphicsview/diagramscene/diagramtextitem.h
@@ -52,12 +52,8 @@
 #define DIAGRAMTEXTITEM_H
 
 #include <QGraphicsTextItem>
-#include <QPen>
 
 QT_BEGIN_NAMESPACE
-class QFocusEvent;
-class QGraphicsItem;
-class QGraphicsScene;
 class QGraphicsSceneMouseEvent;
 QT_END_NAMESPACE
 
@@ -69,7 +65,7 @@ class DiagramTextItem : public QGraphicsTextItem
 public:
     enum { Type = UserType + 3 };
 
-    DiagramTextItem(QGraphicsItem *parent = 0);
+    DiagramTextItem(QGraphicsItem *parent = nullptr);
 
     int type() const override { return Type; }
 
diff --git a/examples/widgets/graphicsview/dragdroprobot/coloritem.cpp b/examples/widgets/graphicsview/dragdroprobot/coloritem.cpp
index 262e18a317..23fb5fda50 100644
--- a/examples/widgets/graphicsview/dragdroprobot/coloritem.cpp
+++ b/examples/widgets/graphicsview/dragdroprobot/coloritem.cpp
@@ -48,10 +48,18 @@
 **
 ****************************************************************************/
 
-#include <QtWidgets>
-
 #include "coloritem.h"
 
+#include <QApplication>
+#include <QBitmap>
+#include <QCursor>
+#include <QDrag>
+#include <QGraphicsSceneMouseEvent>
+#include <QMimeData>
+#include <QPainter>
+#include <QRandomGenerator>
+#include <QWidget>
+
 //! [0]
 ColorItem::ColorItem()
     : color(QRandomGenerator::global()->bounded(256), QRandomGenerator::global()->bounded(256), QRandomGenerator::global()->bounded(256))
@@ -128,7 +136,7 @@ void ColorItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
         QPainter painter(&pixmap);
         painter.translate(15, 15);
         painter.setRenderHint(QPainter::Antialiasing);
-        paint(&painter, 0, 0);
+        paint(&painter, nullptr, nullptr);
         painter.end();
 
         pixmap.setMask(pixmap.createHeuristicMask());
diff --git a/examples/widgets/graphicsview/dragdroprobot/main.cpp b/examples/widgets/graphicsview/dragdroprobot/main.cpp
index 045e184569..b00e9705d4 100644
--- a/examples/widgets/graphicsview/dragdroprobot/main.cpp
+++ b/examples/widgets/graphicsview/dragdroprobot/main.cpp
@@ -48,19 +48,20 @@
 **
 ****************************************************************************/
 
-#include <QtWidgets>
+#include <QApplication>
+#include <QGraphicsScene>
+#include <QGraphicsView>
 
 #include "coloritem.h"
 #include "robot.h"
 
-#include <math.h>
+#include <cmath>
+
 
 class GraphicsView : public QGraphicsView
 {
 public:
-    GraphicsView(QGraphicsScene *scene) : QGraphicsView(scene)
-    {
-    }
+    using QGraphicsView::QGraphicsView;
 
 protected:
     void resizeEvent(QResizeEvent *) override
@@ -96,7 +97,7 @@ int main(int argc, char **argv)
     view.setViewportUpdateMode(QGraphicsView::BoundingRectViewportUpdate);
     view.setBackgroundBrush(QColor(230, 200, 167));
     view.setWindowTitle("Drag and Drop Robot");
-     view.show();
+    view.show();
 
     return app.exec();
 }
diff --git a/examples/widgets/graphicsview/dragdroprobot/robot.cpp b/examples/widgets/graphicsview/dragdroprobot/robot.cpp
index cc70366872..7457dabf8a 100644
--- a/examples/widgets/graphicsview/dragdroprobot/robot.cpp
+++ b/examples/widgets/graphicsview/dragdroprobot/robot.cpp
@@ -48,13 +48,17 @@
 **
 ****************************************************************************/
 
-#include <QtWidgets>
-
 #include "robot.h"
 
+#include <QGraphicsSceneDragDropEvent>
+#include <QMimeData>
+#include <QPainter>
+#include <QParallelAnimationGroup>
+#include <QPropertyAnimation>
+
 //! [0]
 RobotPart::RobotPart(QGraphicsItem *parent)
-    : QGraphicsObject(parent), color(Qt::lightGray), dragOver(false)
+    : QGraphicsObject(parent), color(Qt::lightGray) 
 {
     setAcceptDrops(true);
 }
@@ -157,11 +161,6 @@ void RobotHead::dropEvent(QGraphicsSceneDragDropEvent *event)
 }
 //! [8]
 
-RobotTorso::RobotTorso(QGraphicsItem *parent)
-    : RobotPart(parent)
-{
-}
-
 QRectF RobotTorso::boundingRect() const
 {
     return QRectF(-30, -20, 60, 60);
diff --git a/examples/widgets/graphicsview/dragdroprobot/robot.h b/examples/widgets/graphicsview/dragdroprobot/robot.h
index e25966c7c4..67f6bb4100 100644
--- a/examples/widgets/graphicsview/dragdroprobot/robot.h
+++ b/examples/widgets/graphicsview/dragdroprobot/robot.h
@@ -62,15 +62,15 @@ QT_END_NAMESPACE
 class RobotPart : public QGraphicsObject
 {
 public:
-    RobotPart(QGraphicsItem *parent = 0);
+    RobotPart(QGraphicsItem *parent = nullptr);
 
 protected:
     void dragEnterEvent(QGraphicsSceneDragDropEvent *event) override;
     void dragLeaveEvent(QGraphicsSceneDragDropEvent *event) override;
     void dropEvent(QGraphicsSceneDragDropEvent *event) override;
 
-    QColor color;
-    bool dragOver;
+    QColor color = Qt::lightGray;
+    bool dragOver = false;
 };
 //! [0]
 
@@ -78,10 +78,10 @@ protected:
 class RobotHead : public RobotPart
 {
 public:
-    RobotHead(QGraphicsItem *parent = 0);
+    RobotHead(QGraphicsItem *parent = nullptr);
 
     QRectF boundingRect() const override;
-    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0) override;
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;
 
 protected:
     void dragEnterEvent(QGraphicsSceneDragDropEvent *event) override;
@@ -96,10 +96,10 @@ private:
 class RobotTorso : public RobotPart
 {
 public:
-    RobotTorso(QGraphicsItem *parent = 0);
+    using RobotPart::RobotPart;
 
     QRectF boundingRect() const override;
-    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0) override;
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;
 };
 //! [2]
 
@@ -107,10 +107,10 @@ public:
 class RobotLimb : public RobotPart
 {
 public:
-    RobotLimb(QGraphicsItem *parent = 0);
+    RobotLimb(QGraphicsItem *parent = nullptr);
 
     QRectF boundingRect() const override;
-    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0) override;
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;
 };
 //! [3]
 
@@ -118,10 +118,10 @@ public:
 class Robot : public RobotPart
 {
 public:
-    Robot(QGraphicsItem *parent = 0);
+    Robot(QGraphicsItem *parent = nullptr);
 
     QRectF boundingRect() const override;
-    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0) override;
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;
 };
 //! [4]
 
diff --git a/examples/widgets/graphicsview/elasticnodes/edge.cpp b/examples/widgets/graphicsview/elasticnodes/edge.cpp
index aec12b4225..9ca8b37f3d 100644
--- a/examples/widgets/graphicsview/elasticnodes/edge.cpp
+++ b/examples/widgets/graphicsview/elasticnodes/edge.cpp
@@ -51,16 +51,14 @@
 #include "edge.h"
 #include "node.h"
 
-#include <qmath.h>
 #include <QPainter>
+#include <QtMath>
 
 //! [0]
 Edge::Edge(Node *sourceNode, Node *destNode)
-    : arrowSize(10)
+    : source(sourceNode), dest(destNode)
 {
-    setAcceptedMouseButtons(0);
-    source = sourceNode;
-    dest = destNode;
+    setAcceptedMouseButtons(Qt::NoButton);
     source->addEdge(this);
     dest->addEdge(this);
     adjust();
diff --git a/examples/widgets/graphicsview/elasticnodes/edge.h b/examples/widgets/graphicsview/elasticnodes/edge.h
index 19072b8b33..048d3ffd02 100644
--- a/examples/widgets/graphicsview/elasticnodes/edge.h
+++ b/examples/widgets/graphicsview/elasticnodes/edge.h
@@ -78,7 +78,7 @@ private:
 
     QPointF sourcePoint;
     QPointF destPoint;
-    qreal arrowSize;
+    qreal arrowSize = 10;
 };
 //! [0]
 
diff --git a/examples/widgets/graphicsview/elasticnodes/graphwidget.cpp b/examples/widgets/graphicsview/elasticnodes/graphwidget.cpp
index 9341d77f8d..a067f82ad7 100644
--- a/examples/widgets/graphicsview/elasticnodes/graphwidget.cpp
+++ b/examples/widgets/graphicsview/elasticnodes/graphwidget.cpp
@@ -59,7 +59,7 @@
 
 //! [0]
 GraphWidget::GraphWidget(QWidget *parent)
-    : QGraphicsView(parent), timerId(0)
+    : QGraphicsView(parent) 
 {
     QGraphicsScene *scene = new QGraphicsScene(this);
     scene->setItemIndexMethod(QGraphicsScene::NoIndex);
@@ -163,7 +163,7 @@ void GraphWidget::timerEvent(QTimerEvent *event)
 {
     Q_UNUSED(event);
 
-    QList<Node *> nodes;
+    QVector<Node *> nodes;
     const QList<QGraphicsItem *> items = scene()->items();
     for (QGraphicsItem *item : items) {
         if (Node *node = qgraphicsitem_cast<Node *>(item))
@@ -190,7 +190,7 @@ void GraphWidget::timerEvent(QTimerEvent *event)
 //! [5]
 void GraphWidget::wheelEvent(QWheelEvent *event)
 {
-    scaleView(pow((double)2, -event->angleDelta().y() / 240.0));
+    scaleView(pow(2., -event->angleDelta().y() / 240.0));
 }
 //! [5]
 #endif
diff --git a/examples/widgets/graphicsview/elasticnodes/graphwidget.h b/examples/widgets/graphicsview/elasticnodes/graphwidget.h
index 5ed6aed452..6d241fa9f1 100644
--- a/examples/widgets/graphicsview/elasticnodes/graphwidget.h
+++ b/examples/widgets/graphicsview/elasticnodes/graphwidget.h
@@ -61,7 +61,7 @@ class GraphWidget : public QGraphicsView
     Q_OBJECT
 
 public:
-    GraphWidget(QWidget *parent = 0);
+    GraphWidget(QWidget *parent = nullptr);
 
     void itemMoved();
 
@@ -81,7 +81,7 @@ protected:
     void scaleView(qreal scaleFactor);
 
 private:
-    int timerId;
+    int timerId = 0;
     Node *centerNode;
 };
 //! [0]
diff --git a/examples/widgets/graphicsview/elasticnodes/node.cpp b/examples/widgets/graphicsview/elasticnodes/node.cpp
index 8d44a167fa..a67e21c4b3 100644
--- a/examples/widgets/graphicsview/elasticnodes/node.cpp
+++ b/examples/widgets/graphicsview/elasticnodes/node.cpp
@@ -75,7 +75,7 @@ void Node::addEdge(Edge *edge)
     edge->adjust();
 }
 
-QList<Edge *> Node::edges() const
+QVector<Edge *> Node::edges() const
 {
     return edgeList;
 }
diff --git a/examples/widgets/graphicsview/elasticnodes/node.h b/examples/widgets/graphicsview/elasticnodes/node.h
index 43ea1fb24b..b160ff37cc 100644
--- a/examples/widgets/graphicsview/elasticnodes/node.h
+++ b/examples/widgets/graphicsview/elasticnodes/node.h
@@ -52,13 +52,10 @@
 #define NODE_H
 
 #include <QGraphicsItem>
-#include <QList>
+#include <QVector>
 
 class Edge;
 class GraphWidget;
-QT_BEGIN_NAMESPACE
-class QGraphicsSceneMouseEvent;
-QT_END_NAMESPACE
 
 //! [0]
 class Node : public QGraphicsItem
@@ -67,7 +64,7 @@ public:
     Node(GraphWidget *graphWidget);
 
     void addEdge(Edge *edge);
-    QList<Edge *> edges() const;
+    QVector<Edge *> edges() const;
 
     enum { Type = UserType + 1 };
     int type() const override { return Type; }
@@ -86,7 +83,7 @@ protected:
     void mouseReleaseEvent(QGraphicsSceneMouseEvent *event) override;
 
 private:
-    QList<Edge *> edgeList;
+    QVector<Edge *> edgeList;
     QPointF newPos;
     GraphWidget *graph;
 };
diff --git a/examples/widgets/graphicsview/embeddeddialogs/customproxy.cpp b/examples/widgets/graphicsview/embeddeddialogs/customproxy.cpp
index f510ebc07f..6eda94e8ba 100644
--- a/examples/widgets/graphicsview/embeddeddialogs/customproxy.cpp
+++ b/examples/widgets/graphicsview/embeddeddialogs/customproxy.cpp
@@ -50,14 +50,13 @@
 
 #include "customproxy.h"
 
-#include <QStyleOptionGraphicsItem>
-#include <QPainter>
 #include <QGraphicsScene>
+#include <QPainter>
+#include <QStyleOptionGraphicsItem>
 
 CustomProxy::CustomProxy(QGraphicsItem *parent, Qt::WindowFlags wFlags)
-    : QGraphicsProxyWidget(parent, wFlags), popupShown(false), currentPopup(nullptr)
+    : QGraphicsProxyWidget(parent, wFlags), timeLine(new QTimeLine(250, this))
 {
-    timeLine = new QTimeLine(250, this);
     connect(timeLine, &QTimeLine::valueChanged,
             this, &CustomProxy::updateStep);
     connect(timeLine, &QTimeLine::stateChanged,
@@ -99,7 +98,7 @@ void CustomProxy::hoverEnterEvent(QGraphicsSceneHoverEvent *event)
 {
     QGraphicsProxyWidget::hoverEnterEvent(event);
     scene()->setActiveWindow(this);
-    if (timeLine->currentValue() != 1)
+    if (qFuzzyCompare(timeLine->currentValue(), 1))
         zoomIn();
 }
 
@@ -107,7 +106,7 @@ void CustomProxy::hoverLeaveEvent(QGraphicsSceneHoverEvent *event)
 {
     QGraphicsProxyWidget::hoverLeaveEvent(event);
     if (!popupShown
-            && (timeLine->direction() != QTimeLine::Backward || timeLine->currentValue() != 0)) {
+            && (timeLine->direction() != QTimeLine::Backward || qFuzzyIsNull(timeLine->currentValue()))) {
         zoomOut();
     }
 }
diff --git a/examples/widgets/graphicsview/embeddeddialogs/customproxy.h b/examples/widgets/graphicsview/embeddeddialogs/customproxy.h
index 36209b7073..d7df2b7b4b 100644
--- a/examples/widgets/graphicsview/embeddeddialogs/customproxy.h
+++ b/examples/widgets/graphicsview/embeddeddialogs/customproxy.h
@@ -59,7 +59,7 @@ class CustomProxy : public QGraphicsProxyWidget
     Q_OBJECT
 
 public:
-    explicit CustomProxy(QGraphicsItem *parent = 0, Qt::WindowFlags wFlags = 0);
+    explicit CustomProxy(QGraphicsItem *parent = nullptr, Qt::WindowFlags wFlags = nullptr);
 
     QRectF boundingRect() const override;
     void paintWindowFrame(QPainter *painter, const QStyleOptionGraphicsItem *option,
@@ -79,8 +79,8 @@ private slots:
 
 private:
     QTimeLine *timeLine;
-    bool popupShown;
-    QGraphicsItem *currentPopup;
+    QGraphicsItem *currentPopup = nullptr;
+    bool popupShown = false;
 };
 
 #endif // CUSTOMPROXY_H
diff --git a/examples/widgets/graphicsview/embeddeddialogs/embeddeddialog.h b/examples/widgets/graphicsview/embeddeddialogs/embeddeddialog.h
index 29daaa58c1..c2d87a5660 100644
--- a/examples/widgets/graphicsview/embeddeddialogs/embeddeddialog.h
+++ b/examples/widgets/graphicsview/embeddeddialogs/embeddeddialog.h
@@ -64,7 +64,7 @@ class EmbeddedDialog : public QDialog
     Q_OBJECT
 
 public:
-    EmbeddedDialog(QWidget *parent = 0);
+    EmbeddedDialog(QWidget *parent = nullptr);
     ~EmbeddedDialog();
 
 private slots:
diff --git a/examples/widgets/graphicsview/flowlayout/flowlayout.cpp b/examples/widgets/graphicsview/flowlayout/flowlayout.cpp
index ab6bbb7aa4..54914b3746 100644
--- a/examples/widgets/graphicsview/flowlayout/flowlayout.cpp
+++ b/examples/widgets/graphicsview/flowlayout/flowlayout.cpp
@@ -50,14 +50,10 @@
 
 #include "flowlayout.h"
 
-#include <qmath.h>
+#include <QtMath>
 
-#include <QWidget>
-
-FlowLayout::FlowLayout()
+FlowLayout::FlowLayout(QGraphicsLayoutItem *parent) : QGraphicsLayout(parent)
 {
-    m_spacing[0] = 6;
-    m_spacing[1] = 6;
     QSizePolicy sp = sizePolicy();
     sp.setHeightForWidth(true);
     setSizePolicy(sp);
@@ -66,7 +62,7 @@ FlowLayout::FlowLayout()
 void FlowLayout::insertItem(int index, QGraphicsLayoutItem *item)
 {
     item->setParentLayoutItem(this);
-    if (uint(index) > uint(m_items.count()))
+    if (index > m_items.count())
         index = m_items.count();
     m_items.insert(index, item);
     invalidate();
@@ -117,15 +113,14 @@ qreal FlowLayout::doLayout(const QRectF &geom, bool applyNewGeometry) const
     qreal y = 0;
     qreal maxRowHeight = 0;
     QSizeF pref;
-    for (int i = 0; i < m_items.count(); ++i) {
-        QGraphicsLayoutItem *item = m_items.at(i);
+    for (QGraphicsLayoutItem *item : m_items) {
         pref = item->effectiveSizeHint(Qt::PreferredSize);
         maxRowHeight = qMax(maxRowHeight, pref.height());
 
         qreal next_x;
         next_x = x + pref.width();
         if (next_x > maxw) {
-            if (x == 0) {
+            if (qFuzzyIsNull(x)) {
                 pref.setWidth(maxw);
             } else {
                 x = 0;
@@ -156,7 +151,7 @@ QSizeF FlowLayout::minSize(const QSizeF &constraint) const
     } else {
         for (const QGraphicsLayoutItem *item : qAsConst(m_items))
             size = size.expandedTo(item->effectiveSizeHint(Qt::MinimumSize));
-        size += QSize(left + right, top + bottom);
+        size += QSizeF(left + right, top + bottom);
     }
     return size;
 }
@@ -164,7 +159,7 @@ QSizeF FlowLayout::minSize(const QSizeF &constraint) const
 QSizeF FlowLayout::prefSize() const
 {
     qreal left, right;
-    getContentsMargins(&left, 0, &right, 0);
+    getContentsMargins(&left, nullptr, &right, nullptr);
 
     qreal maxh = 0;
     qreal totalWidth = 0;
diff --git a/examples/widgets/graphicsview/flowlayout/flowlayout.h b/examples/widgets/graphicsview/flowlayout/flowlayout.h
index 808f5d2c77..c6758414d6 100644
--- a/examples/widgets/graphicsview/flowlayout/flowlayout.h
+++ b/examples/widgets/graphicsview/flowlayout/flowlayout.h
@@ -53,7 +53,7 @@
 class FlowLayout : public QGraphicsLayout
 {
 public:
-    FlowLayout();
+    FlowLayout(QGraphicsLayoutItem *parent = nullptr);
     inline void addItem(QGraphicsLayoutItem *item);
     void insertItem(int index, QGraphicsLayoutItem *item);
     void setSpacing(Qt::Orientations o, qreal spacing);
@@ -75,8 +75,8 @@ private:
     QSizeF prefSize() const;
     QSizeF maxSize() const;
 
-    QList<QGraphicsLayoutItem*> m_items;
-    qreal m_spacing[2];
+    QVector<QGraphicsLayoutItem*> m_items;
+    qreal m_spacing[2] = {6, 6};
 };
 
 
diff --git a/examples/widgets/graphicsview/flowlayout/main.cpp b/examples/widgets/graphicsview/flowlayout/main.cpp
index 74c03b9bce..dbfed51bb3 100644
--- a/examples/widgets/graphicsview/flowlayout/main.cpp
+++ b/examples/widgets/graphicsview/flowlayout/main.cpp
@@ -59,12 +59,12 @@ int main(int argc, char *argv[])
     QApplication app(argc, argv);
 
     QGraphicsScene scene;
-    QGraphicsView *view = new QGraphicsView(&scene);
+    QGraphicsView view(&scene);
     Window *w = new Window;
     scene.addItem(w);
 
-    view->resize(400, 300);
-    view->show();
+    view.resize(400, 300);
+    view.show();
 
     return app.exec();
 }
diff --git a/examples/widgets/graphicsview/flowlayout/window.cpp b/examples/widgets/graphicsview/flowlayout/window.cpp
index 34d0d71b44..8fe06d0e11 100644
--- a/examples/widgets/graphicsview/flowlayout/window.cpp
+++ b/examples/widgets/graphicsview/flowlayout/window.cpp
@@ -48,23 +48,21 @@
 **
 ****************************************************************************/
 
-#include "flowlayout.h"
 #include "window.h"
+#include "flowlayout.h"
 
 #include <QGraphicsProxyWidget>
 #include <QLabel>
 
-Window::Window()
-: QGraphicsWidget(0, Qt::Window)
+Window::Window(QGraphicsItem *parent) : QGraphicsWidget(parent, Qt::Window)
 {
     FlowLayout *lay = new FlowLayout;
-    QLatin1String wiseWords("I am not bothered by the fact that I am unknown."
-                            " I am bothered when I do not know others. (Confucius)");
-    QString sentence(wiseWords);
-    QStringList words = sentence.split(QLatin1Char(' '), QString::SkipEmptyParts);
-    for (int i = 0; i < words.count(); ++i) {
+    const QString sentence(QLatin1String("I am not bothered by the fact that I am unknown."
+                                         " I am bothered when I do not know others. (Confucius)"));
+    const QVector<QStringRef> words = sentence.splitRef(QLatin1Char(' '), QString::SkipEmptyParts);
+    for (const QStringRef &word : words) {
         QGraphicsProxyWidget *proxy = new QGraphicsProxyWidget(this);
-        QLabel *label = new QLabel(words.at(i));
+        QLabel *label = new QLabel(word.toString());
         label->setFrameStyle(QFrame::Box | QFrame::Plain);
         proxy->setWidget(label);
         lay->addItem(proxy);
diff --git a/examples/widgets/graphicsview/flowlayout/window.h b/examples/widgets/graphicsview/flowlayout/window.h
index 7f37c447d1..24a7cf908b 100644
--- a/examples/widgets/graphicsview/flowlayout/window.h
+++ b/examples/widgets/graphicsview/flowlayout/window.h
@@ -53,7 +53,6 @@
 class Window : public QGraphicsWidget
 {
     Q_OBJECT
-
 public:
-    Window();
+    Window(QGraphicsItem *parent = nullptr);
 };
diff --git a/examples/widgets/graphicsview/padnavigator/flippablepad.cpp b/examples/widgets/graphicsview/padnavigator/flippablepad.cpp
index e5de331597..6a9097a736 100644
--- a/examples/widgets/graphicsview/padnavigator/flippablepad.cpp
+++ b/examples/widgets/graphicsview/padnavigator/flippablepad.cpp
@@ -75,8 +75,8 @@ FlippablePad::FlippablePad(const QSize &size, QGraphicsItem *parent)
 //! [2]
 //! [3]
     int numIcons = size.width() * size.height();
-    QList<QPixmap> pixmaps;
-    QDirIterator it(":/images", QStringList() << "*.png");
+    QVector<QPixmap> pixmaps;
+    QDirIterator it(":/images", {"*.png"});
     while (it.hasNext() && pixmaps.size() < numIcons)
         pixmaps << it.next();
 //! [3]
diff --git a/examples/widgets/graphicsview/padnavigator/flippablepad.h b/examples/widgets/graphicsview/padnavigator/flippablepad.h
index 323ace4372..ef757c47fb 100644
--- a/examples/widgets/graphicsview/padnavigator/flippablepad.h
+++ b/examples/widgets/graphicsview/padnavigator/flippablepad.h
@@ -53,15 +53,13 @@
 
 #include "roundrectitem.h"
 
-#include <QGraphicsObject>
-#include <QLinearGradient>
 #include <QVector>
 
 //! [0]
 class FlippablePad : public RoundRectItem
 {
 public:
-    explicit FlippablePad(const QSize &size, QGraphicsItem *parent = 0);
+    explicit FlippablePad(const QSize &size, QGraphicsItem *parent = nullptr);
 
     RoundRectItem *iconAt(int column, int row) const;
 
diff --git a/examples/widgets/graphicsview/padnavigator/padnavigator.cpp b/examples/widgets/graphicsview/padnavigator/padnavigator.cpp
index ef0b0b4510..b9ce2a47ca 100644
--- a/examples/widgets/graphicsview/padnavigator/padnavigator.cpp
+++ b/examples/widgets/graphicsview/padnavigator/padnavigator.cpp
@@ -52,10 +52,18 @@
 #include "padnavigator.h"
 #include "splashitem.h"
 
+#include <QEventTransition>
+#include <QGraphicsProxyWidget>
+#include <QGraphicsRotation>
+#include <QHistoryState>
+#include <QKeyEventTransition>
+#include <QParallelAnimationGroup>
+#include <QPropertyAnimation>
+#include <QSequentialAnimationGroup>
+#include <QStateMachine>
+
 #ifndef QT_NO_OPENGL
-#include <QtOpenGL>
-#else
-#include <QtWidgets>
+#include <QOpenGLWidget>
 #endif
 
 //! [0]
diff --git a/examples/widgets/graphicsview/padnavigator/padnavigator.h b/examples/widgets/graphicsview/padnavigator/padnavigator.h
index 00cf2c0212..0fe9ad045d 100644
--- a/examples/widgets/graphicsview/padnavigator/padnavigator.h
+++ b/examples/widgets/graphicsview/padnavigator/padnavigator.h
@@ -54,17 +54,12 @@
 #include <QGraphicsView>
 #include "ui_form.h"
 
-QT_BEGIN_NAMESPACE
-class QState;
-class QStateMachine;
-QT_END_NAMESPACE
-
 //! [0]
 class PadNavigator : public QGraphicsView
 {
     Q_OBJECT
 public:
-    explicit PadNavigator(const QSize &size, QWidget *parent = 0);
+    explicit PadNavigator(const QSize &size, QWidget *parent = nullptr);
 
 protected:
     void resizeEvent(QResizeEvent *event) override;
diff --git a/examples/widgets/graphicsview/padnavigator/roundrectitem.cpp b/examples/widgets/graphicsview/padnavigator/roundrectitem.cpp
index 82205050ec..b4ea489069 100644
--- a/examples/widgets/graphicsview/padnavigator/roundrectitem.cpp
+++ b/examples/widgets/graphicsview/padnavigator/roundrectitem.cpp
@@ -50,7 +50,7 @@
 
 #include "roundrectitem.h"
 
-#include <QApplication>
+#include <QGuiApplication>
 #include <QPainter>
 #include <QPalette>
 
@@ -98,7 +98,7 @@ void RoundRectItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *opt
 //! [3]
 //! [4]
     if (fillRect)
-        painter->setBrush(QApplication::palette().brush(QPalette::Window));
+        painter->setBrush(QGuiApplication::palette().brush(QPalette::Window));
     else
         painter->setBrush(gradient);
     painter->setPen(QPen(Qt::black, 1));
diff --git a/examples/widgets/graphicsview/padnavigator/roundrectitem.h b/examples/widgets/graphicsview/padnavigator/roundrectitem.h
index e76862c08c..91b3e6542e 100644
--- a/examples/widgets/graphicsview/padnavigator/roundrectitem.h
+++ b/examples/widgets/graphicsview/padnavigator/roundrectitem.h
@@ -61,13 +61,13 @@ class RoundRectItem : public QGraphicsObject
     Q_PROPERTY(bool fill READ fill WRITE setFill)
 public:
     RoundRectItem(const QRectF &bounds, const QColor &color,
-                  QGraphicsItem *parent = 0);
+                  QGraphicsItem *parent = nullptr);
 
     QPixmap pixmap() const;
     void setPixmap(const QPixmap &pixmap);
 
     QRectF boundingRect() const override;
-    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0) override;
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;
 
     bool fill() const;
     void setFill(bool fill);
diff --git a/examples/widgets/graphicsview/padnavigator/splashitem.h b/examples/widgets/graphicsview/padnavigator/splashitem.h
index 2ad54f82a1..b8e723db81 100644
--- a/examples/widgets/graphicsview/padnavigator/splashitem.h
+++ b/examples/widgets/graphicsview/padnavigator/splashitem.h
@@ -58,10 +58,10 @@ class SplashItem : public QGraphicsObject
 {
     Q_OBJECT
 public:
-    explicit SplashItem(QGraphicsItem *parent = 0);
+    explicit SplashItem(QGraphicsItem *parent = nullptr);
 
     QRectF boundingRect() const override;
-    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0) override;
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;
 
 private:
     QString text;
diff --git a/examples/widgets/graphicsview/simpleanchorlayout/main.cpp b/examples/widgets/graphicsview/simpleanchorlayout/main.cpp
index 299a5ad7bd..a5f450c1f9 100644
--- a/examples/widgets/graphicsview/simpleanchorlayout/main.cpp
+++ b/examples/widgets/graphicsview/simpleanchorlayout/main.cpp
@@ -54,7 +54,7 @@ class Widget : public QGraphicsWidget
 {
 public:
     Widget(const QColor &color, const QColor &textColor, const QString &caption,
-           QGraphicsItem *parent = 0)
+           QGraphicsItem *parent = nullptr)
         : QGraphicsWidget(parent)
         , caption(caption)
         , color(color)
@@ -62,7 +62,7 @@ public:
     {
     }
 
-    void paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget * = 0) override
+    void paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget * = nullptr) override
     {
         QFont font;
         font.setPixelSize(0.75 * qMin(boundingRect().width(), boundingRect().height()));
@@ -85,7 +85,7 @@ int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
 
-    QGraphicsScene *scene = new QGraphicsScene();
+    QGraphicsScene scene;
 
     Widget *a = new Widget(Qt::blue, Qt::white, "a");
     a->setPreferredSize(100, 100);
@@ -94,7 +94,7 @@ int main(int argc, char *argv[])
     Widget *c = new Widget(Qt::red, Qt::black, "c");
     c->setPreferredSize(100, 100);
 
-    QGraphicsAnchorLayout *layout = new QGraphicsAnchorLayout();
+    QGraphicsAnchorLayout *layout = new QGraphicsAnchorLayout;
 /*
     //! [adding a corner anchor in two steps]
     layout->addAnchor(a, Qt::AnchorTop, layout, Qt::AnchorTop);
@@ -128,20 +128,20 @@ int main(int argc, char *argv[])
     // corner of the layout.
     layout->addCornerAnchors(c, Qt::BottomRightCorner, layout, Qt::BottomRightCorner);
 
-    QGraphicsWidget *w = new QGraphicsWidget(0, Qt::Window | Qt::CustomizeWindowHint | Qt::WindowTitleHint);
+    auto w = new QGraphicsWidget(nullptr, Qt::Window | Qt::CustomizeWindowHint | Qt::WindowTitleHint);
     w->setPos(20, 20);
     w->setMinimumSize(100, 100);
     w->setPreferredSize(320, 240);
     w->setLayout(layout);
     w->setWindowTitle(QApplication::translate("simpleanchorlayout", "QGraphicsAnchorLayout in use"));
-    scene->addItem(w);
+    scene.addItem(w);
 
-    QGraphicsView *view = new QGraphicsView();
-    view->setScene(scene);
-    view->setWindowTitle(QApplication::translate("simpleanchorlayout", "Simple Anchor Layout"));
+    QGraphicsView view;
+    view.setScene(&scene);
+    view.setWindowTitle(QApplication::translate("simpleanchorlayout", "Simple Anchor Layout"));
 
-    view->resize(360, 320);
-    view->show();
+    view.resize(360, 320);
+    view.show();
 
     return app.exec();
 }
diff --git a/examples/widgets/graphicsview/weatheranchorlayout/main.cpp b/examples/widgets/graphicsview/weatheranchorlayout/main.cpp
index 81db2780b4..5c623b1d00 100644
--- a/examples/widgets/graphicsview/weatheranchorlayout/main.cpp
+++ b/examples/widgets/graphicsview/weatheranchorlayout/main.cpp
@@ -50,15 +50,14 @@
 
 #include <QApplication>
 #include <QLabel>
-#include <QPainter>
-#include <QPushButton>
-
 #include <QGraphicsAnchorLayout>
 #include <QGraphicsProxyWidget>
 #include <QGraphicsScene>
 #include <QGraphicsSceneResizeEvent>
 #include <QGraphicsView>
 #include <QGraphicsWidget>
+#include <QPainter>
+#include <QPushButton>
 
 
 class GraphicsView : public QGraphicsView
@@ -79,20 +78,18 @@ public:
 
 class PixmapWidget : public QGraphicsLayoutItem
 {
-
 public:
     PixmapWidget(const QPixmap &pix)
-        : QGraphicsLayoutItem()
+        : QGraphicsLayoutItem(), original(new QGraphicsPixmapItem(pix))
+        , r(QRectF(QPointF(0, 0), pix.size()))
     {
-        original = new QGraphicsPixmapItem(pix);
         setGraphicsItem(original);
         original->show();
-        r = QRectF(QPointF(0, 0), pix.size());
     }
 
     ~PixmapWidget()
     {
-        setGraphicsItem(0);
+        setGraphicsItem(nullptr);
         delete original;
     }
 
@@ -101,7 +98,7 @@ public:
         original->setZValue(z);
     }
 
-    void setGeometry (const QRectF &rect) override
+    void setGeometry(const QRectF &rect) override
     {
         original->setTransform(QTransform::fromScale(rect.width() / r.width(),
                                                      rect.height() / r.height()), true);
@@ -150,8 +147,7 @@ public:
 
     void paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *) override
     {
-        QPointF reflection = QPointF();
-        reflection.setY(scaled.height() + 2);
+        const QPointF reflection(0, scaled.height() + 2);
 
         painter->drawPixmap(QPointF(), scaled);
 
@@ -239,7 +235,7 @@ int main(int argc, char *argv[])
     layout->setSpacing(0);
 
     // setup the main widget
-    QGraphicsWidget *widget = new QGraphicsWidget(0, Qt::Window);
+    QGraphicsWidget *widget = new QGraphicsWidget(nullptr, Qt::Window);
     QPalette p;
     p.setColor(QPalette::Window, Qt::black);
     widget->setPalette(p);