Made QExposeEvent public and added exposeEvent() in QWindow.

This is needed for applications that use QBackingStore directly.

examples/qpa/windows/window.cpp

@@ -38,8 +38,6 @@ Window::Window(QWindow *parent)
     m_image.fill(colorTable[m_backgroundColorIndex % (sizeof(colorTable) / sizeof(colorTable[0]))].rgba());
 
     m_lastPos = QPoint(-1, -1);
-
-    render();
 }
 
 void Window::mousePressEvent(QMouseEvent *event)
@@ -71,6 +69,11 @@ void Window::mouseReleaseEvent(QMouseEvent *event)
     render();
 }
 
+void Window::exposeEvent(QExposeEvent *)
+{
+    render();
+}
+
 void Window::resizeEvent(QResizeEvent *)
 {
     QImage old = m_image;

examples/qpa/windows/window.h

@@ -13,6 +13,7 @@ protected:
 
     void keyPressEvent(QKeyEvent *);
 
+    void exposeEvent(QExposeEvent *);
     void resizeEvent(QResizeEvent *);
 
 private:

src/corelib/kernel/qcoreevent.cpp

@@ -126,6 +126,7 @@ QT_BEGIN_NAMESPACE
     \value Enter                            Mouse enters widget's boundaries.
     \value EnterEditFocus                   An editor widget gains focus for editing.
     \value EnterWhatsThisMode               Send to toplevel widgets when the application enters "What's This?" mode.
+    \value Expose                           Sent to a window when its on-screen contents are invalidated and need to be flushed from the backing store.
     \value FileOpen                         File open request (QFileOpenEvent).
     \value FocusIn                          Widget gains keyboard focus (QFocusEvent).
     \value FocusOut                         Widget loses keyboard focus (QFocusEvent).

src/gui/kernel/qevent.cpp

@@ -1145,6 +1145,29 @@ QMoveEvent::~QMoveEvent()
     Returns the old position of the widget.
 */
 
+/*!
+    \class QExposeEvent
+    \brief The QExposeEvent class contains event parameters for expose events.
+
+    \ingroup events
+
+    Expose events are sent to widgets when an area of the widget is invalidated
+    and needs to be flushed from the backing store.
+
+    The event handler QWindow::exposeEvent() receives expose events.
+*/
+QExposeEvent::QExposeEvent(const QRegion &exposeRegion)
+    : QEvent(Expose)
+    , rgn(exposeRegion)
+{
+}
+
+/*!
+  \internal
+*/
+QExposeEvent::~QExposeEvent()
+{
+}
 
 /*!
     \class QResizeEvent

src/gui/kernel/qevent.h

@@ -300,6 +300,17 @@ protected:
     friend class QCoreApplication;
 };
 
+class Q_GUI_EXPORT QExposeEvent : public QEvent
+{
+public:
+    QExposeEvent(const QRegion &rgn);
+    ~QExposeEvent();
+
+    inline const QRegion &region() const { return rgn; }
+
+protected:
+    QRegion rgn;
+};
 
 class Q_GUI_EXPORT QResizeEvent : public QEvent
 {

src/gui/kernel/qevent_p.h

@@ -167,18 +167,6 @@ public:
     QScrollEvent::ScrollState state;
 };
 
-class QExposeEvent : public QEvent
-{
-public:
-    inline QExposeEvent(const QRegion &rgn)
-        : QEvent(Expose)
-        , region(rgn)
-    {
-    }
-
-    QRegion region;
-};
-
 QT_END_NAMESPACE
 
 #endif // QEVENT_P_H

src/gui/kernel/qwindow.cpp

@@ -454,6 +454,10 @@ bool QWindow::close()
     return true;
 }
 
+void QWindow::exposeEvent(QExposeEvent *)
+{
+}
+
 void QWindow::resizeEvent(QResizeEvent *)
 {
 }
@@ -510,6 +514,10 @@ bool QWindow::event(QEvent *event)
         destroy();
         break;
 
+    case QEvent::Expose:
+        exposeEvent(static_cast<QExposeEvent *>(event));
+        break;
+
     default:
         return QObject::event(event);
     }

src/gui/kernel/qwindow.h

@@ -57,6 +57,7 @@ QT_MODULE(Gui)
 
 class QWindowPrivate;
 
+class QExposeEvent;
 class QResizeEvent;
 class QShowEvent;
 class QHideEvent;
@@ -179,6 +180,7 @@ Q_SIGNALS:
     void backBufferReady();
 
 protected:
+    virtual void exposeEvent(QExposeEvent *);
     virtual void resizeEvent(QResizeEvent *);
 
     virtual void showEvent(QShowEvent *);