Fixed QwtPlotCanvas backingStore feature

Author: PierreRaybaut

CHANGELOG.md

@@ -5,6 +5,7 @@
 - Dropped support for Python 3.7 and earlier
 - Dropped support for PyQt4 and PySide2
 - Removed unnecessary argument `numPoints` in `QwtSymbol.drawSymbols` and `QwtSymbol.renderSymbols` methods
+- `QwtPlotCanvas`: fixed `BackingStore` feature (`paintAttribute`)
 
 ## Version 0.10.6
 

qwt/painter.py

@@ -13,8 +13,7 @@
    :members:
 """
 
-from qtpy import QtCore as QC
-from qtpy.QtCore import QLineF, QPoint, QRect, QRectF, Qt
+from qtpy.QtCore import QLineF, QPoint, QRect, Qt
 from qtpy.QtGui import (
     QBrush,
     QColor,
@@ -27,7 +26,13 @@
     QPixmap,
     QRegion,
 )
-from qtpy.QtWidgets import QFrame, QStyle, QStyleOption, QStyleOptionFocusRect
+from qtpy.QtWidgets import (
+    QApplication,
+    QFrame,
+    QStyle,
+    QStyleOption,
+    QStyleOptionFocusRect,
+)
 
 from qwt.color_map import QwtColorMap
 from qwt.scale_map import QwtScaleMap
@@ -445,13 +450,8 @@ def backingStore(self, widget, size):
         if widget and widget.windowHandle():
             pixelRatio = widget.windowHandle().devicePixelRatio()
         else:
-            from qtpy.QtGui import qApp
-
-            if qApp is not None:
-                try:
-                    pixelRatio = qApp.devicePixelRatio()
-                except RuntimeError:
-                    pass
+            qapp = QApplication.instance()
+            pixelRatio = qapp.devicePixelRatio()
         pm = QPixmap(size * pixelRatio)
         pm.setDevicePixelRatio(pixelRatio)
         return pm

qwt/plot_canvas.py

@@ -15,7 +15,7 @@
 
 import os
 
-from qtpy.QtCore import QEvent, QPointF, QRect, QRectF, QSizeF, Qt
+from qtpy.QtCore import QEvent, QPoint, QPointF, QRect, QRectF, QSize, Qt
 from qtpy.QtGui import (
     QBrush,
     QGradient,
@@ -280,12 +280,12 @@ def qwtFillBackground(*args):
             r = canvas.rect()
             radius = canvas.borderRadius()
             if radius > 0.0:
-                sz = QSizeF(radius, radius)
+                sz = QSize(radius, radius)
                 rects += [
-                    QRectF(r.topLeft(), sz),
-                    QRectF(r.topRight() - QPointF(radius, 0), sz),
-                    QRectF(r.bottomRight() - QPointF(radius, radius), sz),
-                    QRectF(r.bottomLeft() - QPointF(0, radius), sz),
+                    QRect(r.topLeft(), sz),
+                    QRect(r.topRight() - QPoint(radius, 0), sz),
+                    QRect(r.bottomRight() - QPoint(radius, radius), sz),
+                    QRect(r.bottomLeft() - QPoint(0, radius), sz),
                 ]
 
         qwtFillBackground(painter, canvas, rects)
@@ -586,6 +586,7 @@ def paintEvent(self, event):
         if (
             self.testPaintAttribute(self.BackingStore)
             and self.__data.backingStore is not None
+            and not self.__data.backingStore.isNull()
         ):
             bs = self.__data.backingStore
             pixelRatio = bs.devicePixelRatio()

qwt/plot_directpainter.py

@@ -33,7 +33,9 @@ def qwtRenderItem(painter, canvasRect, seriesItem, from_, to):
 
 def qwtHasBackingStore(canvas):
     return (
-        canvas.testPaintAttribute(QwtPlotCanvas.BackingStore) and canvas.backingStore()
+        canvas.testPaintAttribute(QwtPlotCanvas.BackingStore)
+        and canvas.backingStore() is not None
+        and not canvas.backingStore().isNull()
     )
 
 
@@ -207,17 +209,14 @@ def drawSeries(self, seriesItem, from_, to):
             return
         canvas = seriesItem.plot().canvas()
         canvasRect = canvas.contentsRect()
-        plotCanvas = canvas  # XXX: cast to QwtPlotCanvas
-        if plotCanvas and qwtHasBackingStore(plotCanvas):
-            painter = QPainter(
-                plotCanvas.backingStore()
-            )  # XXX: cast plotCanvas.backingStore() to QPixmap
+        if canvas and qwtHasBackingStore(canvas):
+            painter = QPainter(canvas.backingStore())
             if self.__data.hasClipping:
                 painter.setClipRegion(self.__data.clipRegion)
             qwtRenderItem(painter, canvasRect, seriesItem, from_, to)
             painter.end()
             if self.testAttribute(self.FullRepaint):
-                plotCanvas.repaint()
+                canvas.repaint()
                 return
         if canvas.testAttribute(Qt.WA_WState_InPaintEvent):
             if not self.__data.painter.isActive():

qwt/symbol.py

@@ -103,7 +103,7 @@ def qwtDrawSvgSymbols(painter, points, renderer, symbol):
         renderer.render(painter, QRectF(x, y, sz.width(), sz.height()))
 
 
-def qwtDrawGraphicSymbols(painter, points, numPoint, graphic, symbol):
+def qwtDrawGraphicSymbols(painter, points, graphic, symbol):
     pointRect = QRectF(graphic.controlPointRect())
     if pointRect.isEmpty():
         return
@@ -179,7 +179,7 @@ def qwtDrawDiamondSymbols(painter, points, symbol):
         painter.drawPolygon(polygon)
 
 
-def qwtDrawTriangleSymbols(painter, type, points, numPoint, symbol):
+def qwtDrawTriangleSymbols(painter, type, points, symbol):
     size = symbol.size()
     pen = QPen(symbol.pen())
     pen.setJoinStyle(Qt.MiterJoin)

qwt/tests/test_backingstore.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+
+SHOW = False  # Do not show test in GUI-based test launcher
+
+from qwt.tests import utils
+from qwt.tests.test_simple import SimplePlot
+
+
+class BackingStorePlot(SimplePlot):
+    TEST_EXPORT = False
+
+    def __init__(self):
+        SimplePlot.__init__(self)
+        self.canvas().setPaintAttribute(self.canvas().BackingStore, True)
+
+
+def test_backingstore():
+    """Test for backing store"""
+    utils.test_widget(BackingStorePlot, size=(600, 400))
+
+
+if __name__ == "__main__":
+    test_backingstore()

qwt/tests/test_simple.py

@@ -20,6 +20,8 @@
 
 
 class SimplePlot(qwt.QwtPlot):
+    TEST_EXPORT = True
+
     def __init__(self):
         qwt.QwtPlot.__init__(self)
         self.setTitle("Really simple demo")
@@ -28,6 +30,8 @@ def __init__(self):
         self.setAxisTitle(qwt.QwtPlot.yLeft, "Y-axis")
         self.enableAxis(self.xBottom)
         self.setCanvasBackground(Qt.white)
+        canvas = self.canvas()
+        canvas.setBorderRadius(50)
 
         qwt.QwtPlotGrid.make(self, color=Qt.lightGray, width=0, style=Qt.DotLine)
 
@@ -55,7 +59,7 @@ def __init__(self):
             plot=self,
         )
 
-        if utils.TestEnvironment().unattended:
+        if self.TEST_EXPORT and utils.TestEnvironment().unattended:
             QTimer.singleShot(0, self.export_to_different_formats)
 
     def export_to_different_formats(self):