examples: Turn most QPainter instances into context managers

After the new context manager is in place, most of
the examples benefit from moving QPainter into a
`with` statement.

The comments concerning PyPy could be removed, again.

[ChangeLog][PySide6] The examples are updated to use the new
context manager for QPainter.

Task-number: PYSIDE-535
Change-Id: Idf7e1f734d549ed663383ffbb2416297ebb1e0c7
Reviewed-by: Christian Tismer <[email protected]>

4 files changed, 73 insertions, 82 deletions

diff --git a/examples/widgets/painting/basicdrawing/basicdrawing.py b/examples/widgets/painting/basicdrawing/basicdrawing.py
index a0d5bda7c..e89d694fe 100644
--- a/examples/widgets/painting/basicdrawing/basicdrawing.py
+++ b/examples/widgets/painting/basicdrawing/basicdrawing.py
@@ -114,58 +114,56 @@ class RenderArea(QWidget):
         start_angle = 30 * 16
         arc_length = 120 * 16
 
-        painter = QPainter(self)
-        painter.setPen(self.pen)
-        painter.setBrush(self.brush)
-        if self.antialiased:
-            painter.setRenderHint(QPainter.Antialiasing)
-
-        for x in range(0, self.width(), 100):
-            for y in range(0, self.height(), 100):
-                painter.save()
-                painter.translate(x, y)
-                if self.transformed:
-                    painter.translate(50, 50)
-                    painter.rotate(60.0)
-                    painter.scale(0.6, 0.9)
-                    painter.translate(-50, -50)
-
-                if self.shape == RenderArea.Line:
-                    painter.drawLine(rect.bottomLeft(), rect.topRight())
-                elif self.shape == RenderArea.Points:
-                    painter.drawPoints(RenderArea.points)
-                elif self.shape == RenderArea.Polyline:
-                    painter.drawPolyline(RenderArea.points)
-                elif self.shape == RenderArea.Polygon:
-                    painter.drawPolygon(RenderArea.points)
-                elif self.shape == RenderArea.Rect:
-                    painter.drawRect(rect)
-                elif self.shape == RenderArea.RoundedRect:
-                    painter.drawRoundedRect(rect, 25, 25, Qt.RelativeSize)
-                elif self.shape == RenderArea.Ellipse:
-                    painter.drawEllipse(rect)
-                elif self.shape == RenderArea.Arc:
-                    painter.drawArc(rect, start_angle, arc_length)
-                elif self.shape == RenderArea.Chord:
-                    painter.drawChord(rect, start_angle, arc_length)
-                elif self.shape == RenderArea.Pie:
-                    painter.drawPie(rect, start_angle, arc_length)
-                elif self.shape == RenderArea.Path:
-                    painter.drawPath(path)
-                elif self.shape == RenderArea.Text:
-                    qv = qVersion()
-                    painter.drawText(rect, Qt.AlignCenter,
-                                     f"PySide 6\nQt {qv}")
-                elif self.shape == RenderArea.Pixmap:
-                    painter.drawPixmap(10, 10, self.pixmap)
-
-                painter.restore()
-
-        painter.setPen(self.palette().dark().color())
-        painter.setBrush(Qt.NoBrush)
-        painter.drawRect(QRect(0, 0, self.width() - 1, self.height() - 1))
-        # QPainter needs an explicit end() in PyPy. This will become a context manager in 6.3.
-        painter.end()
+        with QPainter(self) as painter:
+            painter.setPen(self.pen)
+            painter.setBrush(self.brush)
+            if self.antialiased:
+                painter.setRenderHint(QPainter.Antialiasing)
+
+            for x in range(0, self.width(), 100):
+                for y in range(0, self.height(), 100):
+                    painter.save()
+                    painter.translate(x, y)
+                    if self.transformed:
+                        painter.translate(50, 50)
+                        painter.rotate(60.0)
+                        painter.scale(0.6, 0.9)
+                        painter.translate(-50, -50)
+
+                    if self.shape == RenderArea.Line:
+                        painter.drawLine(rect.bottomLeft(), rect.topRight())
+                    elif self.shape == RenderArea.Points:
+                        painter.drawPoints(RenderArea.points)
+                    elif self.shape == RenderArea.Polyline:
+                        painter.drawPolyline(RenderArea.points)
+                    elif self.shape == RenderArea.Polygon:
+                        painter.drawPolygon(RenderArea.points)
+                    elif self.shape == RenderArea.Rect:
+                        painter.drawRect(rect)
+                    elif self.shape == RenderArea.RoundedRect:
+                        painter.drawRoundedRect(rect, 25, 25, Qt.RelativeSize)
+                    elif self.shape == RenderArea.Ellipse:
+                        painter.drawEllipse(rect)
+                    elif self.shape == RenderArea.Arc:
+                        painter.drawArc(rect, start_angle, arc_length)
+                    elif self.shape == RenderArea.Chord:
+                        painter.drawChord(rect, start_angle, arc_length)
+                    elif self.shape == RenderArea.Pie:
+                        painter.drawPie(rect, start_angle, arc_length)
+                    elif self.shape == RenderArea.Path:
+                        painter.drawPath(path)
+                    elif self.shape == RenderArea.Text:
+                        qv = qVersion()
+                        painter.drawText(rect, Qt.AlignCenter,
+                                         f"PySide 6\nQt {qv}")
+                    elif self.shape == RenderArea.Pixmap:
+                        painter.drawPixmap(10, 10, self.pixmap)
+
+                    painter.restore()
+
+            painter.setPen(self.palette().dark().color())
+            painter.setBrush(Qt.NoBrush)
+            painter.drawRect(QRect(0, 0, self.width() - 1, self.height() - 1))
 
 
 id_role = Qt.UserRole
diff --git a/examples/widgets/painting/concentriccircles/concentriccircles.py b/examples/widgets/painting/concentriccircles/concentriccircles.py
index 2786396cb..c6bada0a6 100644
--- a/examples/widgets/painting/concentriccircles/concentriccircles.py
+++ b/examples/widgets/painting/concentriccircles/concentriccircles.py
@@ -78,25 +78,22 @@ class CircleWidget(QWidget):
         self.update()
 
     def paintEvent(self, event):
-        painter = QPainter(self)
-        painter.setRenderHint(QPainter.Antialiasing, self.antialiased)
-        painter.translate(self.width() / 2, self.height() / 2)
-
-        for diameter in range(0, 256, 9):
-            delta = abs((self._frame_no % 128) - diameter / 2)
-            alpha = 255 - (delta * delta) / 4 - diameter
-            if alpha > 0:
-                painter.setPen(QPen(QColor(0, diameter / 2, 127, alpha), 3))
-
-                if self._float_based:
-                    painter.drawEllipse(QRectF(-diameter / 2.0,
-                            -diameter / 2.0, diameter, diameter))
-                else:
-                    painter.drawEllipse(QRect(-diameter / 2,
-                            -diameter / 2, diameter, diameter))
-
-        # QPainter needs an explicit end() in PyPy. This will become a context manager in 6.3.
-        painter.end()
+        with QPainter(self) as painter:
+            painter.setRenderHint(QPainter.Antialiasing, self.antialiased)
+            painter.translate(self.width() / 2, self.height() / 2)
+
+            for diameter in range(0, 256, 9):
+                delta = abs((self._frame_no % 128) - diameter / 2)
+                alpha = 255 - (delta * delta) / 4 - diameter
+                if alpha > 0:
+                    painter.setPen(QPen(QColor(0, diameter / 2, 127, alpha), 3))
+
+                    if self._float_based:
+                        painter.drawEllipse(QRectF(-diameter / 2.0,
+                                -diameter / 2.0, diameter, diameter))
+                    else:
+                        painter.drawEllipse(QRect(-diameter / 2,
+                                -diameter / 2, diameter, diameter))
 
 
 class Window(QWidget):
diff --git a/examples/widgets/painting/painter/painter.py b/examples/widgets/painting/painter/painter.py
index 3d5d95f10..6626afb7a 100644
--- a/examples/widgets/painting/painter/painter.py
+++ b/examples/widgets/painting/painter/painter.py
@@ -88,10 +88,8 @@ class PainterWidget(QWidget):
         Paint the Pixmap into the widget
 
         """
-        painter = QPainter()
-        painter.begin(self)
-        painter.drawPixmap(0, 0, self.pixmap)
-        painter.end()
+        with QPainter(self) as painter:
+            painter.drawPixmap(0, 0, self.pixmap)
 
     def mousePressEvent(self, event: QMouseEvent):
         """Override from QWidget
diff --git a/examples/widgets/painting/plot/plot.py b/examples/widgets/painting/plot/plot.py
index a125c3253..30dc3e504 100644
--- a/examples/widgets/painting/plot/plot.py
+++ b/examples/widgets/painting/plot/plot.py
@@ -88,13 +88,11 @@ class PlotWidget(QWidget):
         self.update()
 
     def paintEvent(self, event):
-        painter = QPainter()
-        painter.begin(self)
-        rect = QRect(QPoint(0, 0), self.size())
-        painter.fillRect(rect, Qt.white)
-        painter.translate(-self._points[0].x(), 0)
-        painter.drawPolyline(self._points)
-        painter.end()
+        with QPainter(self) as painter:
+            rect = QRect(QPoint(0, 0), self.size())
+            painter.fillRect(rect, Qt.white)
+            painter.translate(-self._points[0].x(), 0)
+            painter.drawPolyline(self._points)
 
 
 if __name__ == "__main__":