fix issues with PyQt5, add more usage information

Author: Jovan Mitrevski

README.md

@@ -9,6 +9,61 @@ In order to use matplotlib plots with QtQuick, do the following:
 1. In your QML files, instantiate an object with the QML type defined above. Its `objectName` property specifies the name of the object that can be found in the QML engine. It can be retrieved in python with `win.findChild(QtCore.QObject, "spectFigure")`, for example, where `"spectFigure"` is the `objectName` in this case.
 1. One can then pass this object as needed. This is the FigureCanvasQtQuickAgg object. The figure can be found in its `figure` property.
 
-The test in the ``tests`` directory gives a simple example of how to use this backend.
+The test in the `tests` directory gives a simple example of how to use this backend.
+
+For interactive plots, if you want to use the toolbar, to the `Bridge` class add slots like:
+
+```python
+    @QtCore.Slot()
+    def zoom(self, *args):
+        """activate zoom tool."""
+        self.toolbar.zoom(*args)
+```
+
+One can also connect to Matplotlib events:
+
+```python
+       self._figure.canvas.mpl_connect('button_press_event', self.onClick)
+       self._figure.canvas.mpl_connect('scroll_event', self.onScroll)
+```
+
+and provide the callbacks, for example:
+
+```python
+    def onClick(self, event):
+        """
+        Handle mouse clicks in the three slices:
+        set the slice to what is clicked.
+        """
+        if event.button == MouseButton.LEFT:
+            if event.inaxes == self.axeses[0]:
+                self.x = self._findBin(self.xAxis, event.xdata)
+                self.y = self._findBin(self.yAxis, event.ydata)
+                self.setSlice()
+            elif event.inaxes == self.axeses[1]:
+                self.x = self._findBin(self.xAxis, event.xdata)
+                self.z = self._findBin(self.zAxis, event.ydata)
+                self.setSlice()
+            elif event.inaxes == self.axeses[2]:
+                self.y = self._findBin(self.yAxis, event.xdata)
+                self.z = self._findBin(self.zAxis, event.ydata)
+                self.setSlice()
+
+    def onScroll(self, event):
+        """
+        Handle mouse scroll in the three slices
+        - scroll the independent variable
+        """
+        if event.inaxes == self.axeses[0]:
+            self.z += int(event.step)
+            self.setSlice()
+        elif event.inaxes == self.axeses[1]:
+            self.y += int(event.step)
+            self.setSlice()
+        elif event.inaxes == self.axeses[2]:
+            self.x += int(event.step)
+            self.setSlice()
+```
+
 
 Please let me know if you have any suggestions or better ways I should do this.

matplotlib_backend_qtquick/backend_qtquick.py

@@ -11,7 +11,8 @@
 from matplotlib.backends.backend_qt5 import (
     TimerQT, SPECIAL_KEYS, MODIFIER_KEYS, cursord)
 from .qt_compat import (
-    QtCore, QtGui, QtQuick, QtWidgets)
+    QtCore, QtGui, QtQuick, QtWidgets,
+    QT_API, QT_API_PYSIDE2)
 
 
 class FigureCanvasQtQuick(QtQuick.QQuickPaintedItem, FigureCanvasBase):
@@ -71,6 +72,9 @@ def _update_figure_dpi(self):
     def get_dpi_ratio(self):
         return self._dpi_ratio
 
+    def boundingRect(self):
+        return QtCore.QRectF(0, 0, self.width(), self.height())
+
     def set_dpi_ratio(self, new_ratio):
         # As described in __init__ above, we need to be careful in cases with
         # mixed resolution displays if dpi_ratio is changing between painting
@@ -344,8 +348,12 @@ class NavigationToolbar2QtQuick(QtCore.QObject, NavigationToolbar2):
 
     def __init__(self, canvas, parent=None):
 
-        QtCore.QObject.__init__(self, parent)
-        NavigationToolbar2.__init__(self, canvas)
+        # I think this is needed due to a bug in PySide2
+        if QT_API == QT_API_PYSIDE2:
+            QtCore.QObject.__init__(self, parent)
+            NavigationToolbar2.__init__(self, canvas)
+        else:
+            super().__init__(canvas=canvas, parent=parent)
 
         self._message = ""
 

setup.py

@@ -5,7 +5,7 @@
 
 setuptools.setup(
     name="matplotlib_backend_qtquick",
-    version="0.0.5",
+    version="0.0.6",
     author="Jovan Mitrevski",
     author_email="j.p.mitrevski@gmail.com",
     description="A QtQuick backend for matplotlib",

tests/testBackend.py

@@ -1,7 +1,7 @@
 """
 An integration test to create a plot using the qtquick backend.
 """
-
+import sys
 from pathlib import Path
 import unittest
 import numpy as np
@@ -46,7 +46,7 @@ class TestBackend(unittest.TestCase):
 
     def test_basicPlotting(self):
         QtCore.QCoreApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling)
-        app = QtGui.QGuiApplication()
+        app = QtGui.QGuiApplication(sys.argv)
         engine = QtQml.QQmlApplicationEngine()
 
         # instantate the display bridge