Use QPainterStateGuard in examples

Complements 9ecf47a8a8d11227ecf192246d7df7c2c4dc9105.

Pick-to: 6.9
Change-Id: I65456f8fd34bf9d316b72c4286e1b15789309f7c
Reviewed-by: Christian Ehrlicher <ch.ehrlicher@gmx.de>

examples/widgets/doc/src/analogclock.qdoc

@@ -106,11 +106,10 @@
     system counterclockwise by a number of degrees determined by the current
     hour and minute. This means that the hand will be shown rotated clockwise
     by the required amount.
-    We save and restore the transformation matrix before and after the
-    rotation because we want to place the minute hand without having to
-    take into account any previous rotations.
+    We save and restore the transformation matrix before and after the rotation
+    by instantiating a QPainterStateGuard because we want to place the minute
+    hand without having to take into account any previous rotations.
 
-    \snippet widgets/analogclock/analogclock.cpp 17
     \snippet widgets/analogclock/analogclock.cpp 19
 
     We draw markers around the edge of the clock for each hour in the same
@@ -123,7 +122,7 @@
 
     \snippet widgets/analogclock/analogclock.cpp 21
 
-    For the seconds hand we do the same and add two cicles as a visual highlight.
+    For the seconds hand we do the same and add two circles as a visual highlight.
 
     \snippet widgets/analogclock/analogclock.cpp 23
     \codeline

examples/widgets/doc/src/basicdrawing.qdoc

@@ -370,8 +370,8 @@
     RenderArea widget, and we calculate their positions using two \c
     for loops and the widgets height and width.
 
-    For each copy we first save the current painter state (pushes the
-    state onto a stack). Then we translate the coordinate system,
+    For each copy we first save the current painter state by instantiating
+    a QPainterStateGuard. Then we translate the coordinate system,
     using the QPainter::translate() function, to the position
     determined by the variables of the \c for loops. If we omit this
     translation of the coordinate system all the copies of the shape
@@ -420,9 +420,9 @@
 
     \snippet painting/basicdrawing/renderarea.cpp 13
 
-    Then, when we are finished rendering a copy of the shape we can
-    restore the original painter state, with its associated coordinate
-    system, using the QPainter::restore() function. In this way we
+    Then, when we are finished rendering a copy of the shape,
+    the original painter state is restored by QPainterStateGuard,
+    which calls the QPainter::restore() function. In this way, we
     ensure that the next shape copy will be rendered in the correct
     position.
 

examples/widgets/doc/src/transformations.qdoc

@@ -161,13 +161,11 @@
 
     \snippet painting/transformations/renderarea.cpp 6
 
-    Before we start to render the shape, we call the QPainter::save()
-    function.
-
-    QPainter::save() saves the current painter state (i.e. pushes the
-    state onto a stack) including the current coordinate system. The
-    rationale for saving the painter state is that the following call
-    to the \c transformPainter() function will transform the
+    Before we start to render the shape, we instantiate
+    a QPainterStateGuard to save the current painter state (i.e. push the
+    state onto a stack) including the current coordinate system while
+    in scope. The rationale for saving the painter state is that the
+    following call to the \c transformPainter() function will transform the
     coordinate system depending on the currently chosen transformation
     operations, and we need a way to get back to the original state to
     draw the outline.

examples/widgets/painting/affine/xform.cpp

@@ -6,6 +6,7 @@
 
 #include <QLayout>
 #include <QPainter>
+#include <QPainterStateGuard>
 #include <QPainterPath>
 
 const int alpha = 155;
@@ -76,7 +77,7 @@ void XFormView::resizeEvent(QResizeEvent *e)
 
 void XFormView::paint(QPainter *p)
 {
-    p->save();
+    QPainterStateGuard guard(p);
     p->setRenderHint(QPainter::Antialiasing);
     p->setRenderHint(QPainter::SmoothPixmapTransform);
     switch (m_type) {
@@ -90,7 +91,6 @@ void XFormView::paint(QPainter *p)
         drawTextType(p);
         break;
     }
-    p->restore();
 }
 
 void XFormView::updateControlPoints(const QPolygonF &points)

examples/widgets/painting/basicdrawing/renderarea.cpp

@@ -5,6 +5,7 @@
 
 #include <QPainter>
 #include <QPainterPath>
+#include <QPainterStateGuard>
 
 //! [0]
 RenderArea::RenderArea(QWidget *parent)
@@ -106,7 +107,7 @@ void RenderArea::paintEvent(QPaintEvent * /* event */)
 //! [10]
     for (int x = 0; x < width(); x += 100) {
         for (int y = 0; y < height(); y += 100) {
-            painter.save();
+            QPainterStateGuard guard(&painter);
             painter.translate(x, y);
 //! [10] //! [11]
             if (transformed) {
@@ -161,7 +162,6 @@ void RenderArea::paintEvent(QPaintEvent * /* event */)
                 painter.drawPixmap(10, 10, pixmap);
             }
 //! [12] //! [13]
-            painter.restore();
         }
     }
 

examples/widgets/painting/transformations/renderarea.cpp

@@ -4,6 +4,7 @@
 #include "renderarea.h"
 
 #include <QPainter>
+#include <QPainterStateGuard>
 #include <QPaintEvent>
 
 //! [0]
@@ -61,10 +62,11 @@ void RenderArea::paintEvent(QPaintEvent *event)
 //! [5]
 
 //! [6]
-    painter.save();
-    transformPainter(painter);
-    drawShape(painter);
-    painter.restore();
+    {
+        QPainterStateGuard guard(&painter);
+        transformPainter(painter);
+        drawShape(painter);
+    }
 //! [6]
 
 //! [7]

examples/widgets/widgets/analogclock/analogclock.cpp

@@ -4,6 +4,7 @@
 #include "analogclock.h"
 
 #include <QPainter>
+#include <QPainterStateGuard>
 #include <QTime>
 #include <QTimer>
 
@@ -78,12 +79,12 @@ void AnalogClock::paintEvent(QPaintEvent *)
 //! [16]
 //! [18]
 
-//! [17]
-    painter.save();
-//! [17] //! [19]
-    painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
-    painter.drawConvexPolygon(hourHand, 4);
-    painter.restore();
+//! [19]
+    {
+        QPainterStateGuard guard(&painter);
+        painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
+        painter.drawConvexPolygon(hourHand, 4);
+    }
 //! [18] //! [19]
 
 //! [20]
@@ -97,10 +98,11 @@ void AnalogClock::paintEvent(QPaintEvent *)
     painter.setBrush(minuteColor);
 
 //! [22]
-    painter.save();
-    painter.rotate(6.0 * time.minute());
-    painter.drawConvexPolygon(minuteHand, 4);
-    painter.restore();
+    {
+        QPainterStateGuard guard(&painter);
+        painter.rotate(6.0 * time.minute());
+        painter.drawConvexPolygon(minuteHand, 4);
+    }
 //! [21] //! [22]
 
 
@@ -109,12 +111,13 @@ void AnalogClock::paintEvent(QPaintEvent *)
 //! [23]
 
 //! [24]
-    painter.save();
-    painter.rotate(6.0 * time.second());
-    painter.drawConvexPolygon(secondsHand, 4);
-    painter.drawEllipse(-3, -3, 6, 6);
-    painter.drawEllipse(-5, -68, 10, 10);
-    painter.restore();
+    {
+        QPainterStateGuard guard(&painter);
+        painter.rotate(6.0 * time.second());
+        painter.drawConvexPolygon(secondsHand, 4);
+        painter.drawEllipse(-3, -3, 6, 6);
+        painter.drawEllipse(-5, -68, 10, 10);
+    }
 //! [24]
 
 //! [25]

examples/widgets/widgets/shapedclock/shapedclock.cpp

@@ -7,6 +7,7 @@
 #include <QCoreApplication>
 #include <QMouseEvent>
 #include <QPainter>
+#include <QPainterStateGuard>
 #include <QTime>
 #include <QTimer>
 
@@ -93,10 +94,11 @@ void ShapedClock::paintEvent(QPaintEvent *)
     painter.setPen(Qt::NoPen);
     painter.setBrush(hourColor);
 
-    painter.save();
-    painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
-    painter.drawConvexPolygon(hourHand, 4);
-    painter.restore();
+    {
+        QPainterStateGuard guard(&painter);
+        painter.rotate(30.0 * ((time.hour() + time.minute() / 60.0)));
+        painter.drawConvexPolygon(hourHand, 4);
+    }
 
     for (int i = 0; i < 12; ++i) {
         painter.drawRect(73, -3, 16, 6);
@@ -105,19 +107,21 @@ void ShapedClock::paintEvent(QPaintEvent *)
 
     painter.setBrush(minuteColor);
 
-    painter.save();
-    painter.rotate(6.0 * time.minute());
-    painter.drawConvexPolygon(minuteHand, 4);
-    painter.restore();
+    {
+        QPainterStateGuard guard(&painter);
+        painter.rotate(6.0 * time.minute());
+        painter.drawConvexPolygon(minuteHand, 4);
+    }
 
     painter.setBrush(secondsColor);
 
-    painter.save();
-    painter.rotate(6.0 * time.second());
-    painter.drawConvexPolygon(secondsHand, 4);
-    painter.drawEllipse(-3, -3, 6, 6);
-    painter.drawEllipse(-5, -68, 10, 10);
-    painter.restore();
+    {
+        QPainterStateGuard guard(&painter);
+        painter.rotate(6.0 * time.second());
+        painter.drawConvexPolygon(secondsHand, 4);
+        painter.drawEllipse(-3, -3, 6, 6);
+        painter.drawEllipse(-5, -68, 10, 10);
+    }
 
     painter.setPen(minuteColor);