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]>

1 files changed, 8 insertions, 11 deletions

diff --git a/examples/widgets/tutorials/cannon/t10.py b/examples/widgets/tutorials/cannon/t10.py
index 98b5f57fe..0e553f8c5 100644
--- a/examples/widgets/tutorials/cannon/t10.py
+++ b/examples/widgets/tutorials/cannon/t10.py
@@ -129,17 +129,14 @@ class CannonField(QWidget):
         self.force_changed.emit(self._current_force)
 
     def paintEvent(self, event):
-        painter = QPainter(self)
-
-        painter.setPen(Qt.NoPen)
-        painter.setBrush(Qt.blue)
-
-        painter.translate(0, self.height())
-        painter.drawPie(QRect(-35, -35, 70, 70), 0, 90 * 16)
-        painter.rotate(-self._current_angle)
-        painter.drawRect(QRect(33, -4, 15, 8))
-        # 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(Qt.NoPen)
+            painter.setBrush(Qt.blue)
+
+            painter.translate(0, self.height())
+            painter.drawPie(QRect(-35, -35, 70, 70), 0, 90 * 16)
+            painter.rotate(-self._current_angle)
+            painter.drawRect(QRect(33, -4, 15, 8))
 
     def cannon_rect(self):
         result = QRect(0, 0, 50, 50)